Test Methods for Textile Composites - NASA · Test Methods for Textile Composites Pierre J....

NASA Contractor Report 4609

Test Methods for Textile Composites

Pierre J. Minguet, Mark J. Fedro, and Christian K. Gunther

Boeing Defense & Space Group • Philadelphia, Pennsylvania

National Aeronautics and Space AdministrationLangley Research Center • Hampton, Virginia 23681-0001

Prepared for Langley Research Centerunder Contract NAS1-19247

July 1994

https://ntrs.nasa.gov/search.jsp?R=19950006380 2020-03-05T08:16:51+00:00Z

Abstract

Various test methods commonly used for measuring properties of tape laminate

composites were evaluated to determine their suitability for the testing of textile

composites. Three different types of textile composites were utilized in this

investigation: 2-Dimensional triaxial braids, stitched uniweave fabric and 3-

Dimensional interlock woven fabric. Ten categories of material properties were

investigated: Tension, Open-Hole Tension, Compression, Open-Hole Compression, In-

Plane Shear, Filled-Hole Tension , Bolt Bearing, Interlaminar Tension, Interlaminar

Shear and Interlaminar Fracture Toughness.

The main issue in the tension test program was the effect on strength of the

specimen size compared to the material unit cell dimensions. Little or no effect on

strength was observed for the 2-D braids which have the largest unit cell size of all

material tested. The effect of specimen width to hole diameter ratio (W/D) was

investigated in the open-hole tension. Results showed that the standard W/D=6 was

adequate. A comparison of the Boeing Open Hole Compression, Zabora Fixture, NASA

Short Block, NASA 1142, Modified IITRI, sandwich column, Boeing Compression After

Impact and NASA ST-4 specimens was conducted in the compression test program. The

Boeing Open Hole Compression, sandwich column, Boeing Compression After Impact

and NASA ST-4 specimens were found to be inadequate for strength testing. Among the

remaining methods, the NASA Short Block specimen consistently produced the highest

mean strength. In the open hole compression tests, a comparison of the Boeing Open

Hole Compression, Zabora Fixture, NASA Short Block, NASA 1142 and Modified IITRI

was conducted for hole diameters up to 0.375". Results show that the Modified IITRI

produced the highest mean strength, while the Boeing OHC produced the lowest. Both

the Boeing Compression After Impact and NASA ST-4 gave good results for larger hole

from 0.5" to 1.25". For the in-plane shear testing, a comparison of tube torsion, rail shear

and compact shear specimens was conducted. Significant differences in both strength

and modulus were obtained between these test methods. Testing was conducted only

with the 2-D braided material for filled-hole tension strength and confirmed that, as for

tape laminates, filled hole tension is the critical case when developing material design

allowables for the Room Temperature/Dry environment. Testing for bolt bearing

strength was conducted only with the 2-D braided material. As for tape laminates, the

stabilized single shear bearing test is recommended. Testing for interlaminar tension

was conducted with the 2-D braided material and 3-D woven materials using a C-shape

and a L-shape specimens. Strength values from the L-shape configuration were slightly

higher. Testing for interlaminar shear was conducted with the 2-D braided material and

3-D woven materials using the Short Beam Shear (SBS) and Compression Interlaminar

Shear (CIS) specimens. Strength values obtained from the SBS specimen were

consistantly higher than those from the CIS specimen. Testing for interlaminar fracture

toughness was conducted only with the 2-D braided material using the Double

Cantilever Beam and End Notched Flexure specimens. Results showed much higher

toughness in this type material than in conventional laminated composites.

_:'.:_6GIIOW_ PAGE IILANK NOT IFII.MEID

lit

Table of Contents

Abstract ................................................................................................................. I I I

Table of Contents ................................................................................................. Iv

List of Figures ....................................................................................................... v I I

List of Tables ........................................................................................................ x I

1. Introduction ..................................................................................................... 1

2. Material Systems ............................................................................................. 2

2.1 2-D Braided Composites ......................................................................... 2

2.2 Stitched Uniweave Composites ............................................................. 3

2.3 3-D Interlock Woven Materials ............................................................ 4

3. Data Reduction Techniques ........................................................................... 5

3.1 Fiber Volume Measurements ................................................................. 5

3.2 Thickness Normalization ....................................................................... 5

3.3 Stress, Modulus and Poisson's Coefficient Calculation ..................... 7

3.4 Open-Hole Data ....................................................................................... 7

4. Strain Gage Size Sensitivity Study ................................................................ 9

4.1 Test Specimens and Procedures ............................................................ 9

4.2 Strain Gages Investigated ....................................................................... 9

4.3 Experimental Results .............................................................................. 10

4.4 2-D Braided Materials ............................................................................. 11

4.5 3-D Woven Materials .............................................................................. 12

5. In-Plane Tension Test Program ..................................................................... 15

5.1 Test Configuration .................................................................................. 15

5.2 2-D Braid Materials ................................................................................. 16

5.2.1 Test Section Width, Length and Thickness Effects ................. 16

5.2.2 Longitudinal Tension Test Summary ....................................... 185.2.3 Transverse Tension ..................................................................... 20

5.3 Stitched Uniweave Materials ................................................................. 21


5.5 Test Recommendations ........................................................................... 22

6. Open-Hole Tension Test Program ................................................................ 24

6.1 Test Configuration .................................................................................. 24


6.2.1 Width to Diameter Ratio Effect ................................................. 25

6.2.2 Thickness Effect ........................................................................... 26

6.2.3 Hole Size Effect ............................................................................ 26

6.2.4 Summary ...................................................................................... 29




IV

7. In-Plane Compression Test Program ............................................................ 34

7.1 Test Configurations ................................................................................. 34


7.2.1 Test Section Length and Thickness Effects .............................. 37

7.2.2 Longitudinal Compression ........................................................ 387.2.3 Sandwich Column ....................................................................... 41

7.2.4 Boeing Open Hole Compression Fixture ................................. 42

7.2.5 Transverse Compression ............................................................ 42

7.3 Stitched Uniweaves Materials ............................................................... 43

7.3.1 Longitudinal Compression ........................................................ 43



7.4. 1 Longitudinal Compression ....................................................... 44



8. Open Hole Compression Test Program ....................................................... 48



8.2.1 Test Method Comparison ........................................................... 498.2.2 Hole Size Effect ............................................................................ 53




9. In-Plane Shear Test Program ......................................................................... 62





9.5 Test Recommendations .......................................................................... 67

10. Filled-Hole Test Program ............................................................................. 69

10.1 Test Configuration ................................................................................ 69

10.2 2-D Braids ............................................................................................... 69

11. Bolt-Bearing Test Program ........................................................................... 71

11.1 Test Configuration ................................................................................ 71

11.2 2-D Braids ............................................................................................... 73

12. Interlaminar Tension ..................................................................................... 78

12.1 Specimen Configurations ..................................................................... 78

12.2 2-D Braids Materials ............................................................................. 79

12.3 3-D Woven Materials ............................................................................ 81

13. Interlaminar Shear ......................................................................................... 82

13.1 Test Configurations ............................................................................... 82

v

13.3 2-D Braided Materials ........................................................................... 83

13.3 3-D Woven Materials ............................................................................ 84

14. Interlaminar Fracture Toughness ................................................................ 85

14.1 Test Configurations ............................................................................... 85

14.2 2-D Braided Materials ........................................................................... 86

15. Conclusions .................................................................................................... 88

References ............................................................................................................. 90

Appendix A Test Data ........................................................................................ A.1

Appendix B Typical Stress-Strain Curves ........................................................ B. 1

Appendix C Boeing Specifications ................................................................... C.1

VI

Figure 2.1

Figure 2.2

Figure 3.1

Figure 5.1.a

Figure 5.1.b

Figure 5.2.a

Figure 5.2.b

Figure 5.2.c

Figure 5.2.d

Figure 5.3

Figure 5.4

Figure 5.5

Figure 5.6

Figure 5.7

Figure 6.1

Figure 6.2

Figure 6.3

Figure 6.4.a

Figure 6.4.b

Figure 6.4.c

Figure 6.4.d

Figure 6.5

Figure 6.6

Figure 6.7.a

Figure 6.7.b

Figure 6.7.c

Figure 7.1 .a

Figure 7.1.b

List of Figures

Illustration of 2-D Triaxial Braid Configuration ....................................... 3

Depiction of 3-D Interlock Woven Materials ............................................ 4

Example of Relationship between Fiber Volume Fraction and

Thickness for SLL, LSS and SU-1 Specimens ............................................ 6

Typical Tension Specimen Configuration ................................................. 15

Dogbone Tension Specimen Configuration .............................................. 16

Effect of Specimen Width on Tensile Strength of 2-D Braid SLL ........... 17

Effect of Specimen Width on Tensile Strength of 2-D Braid LLS ........... 17

Effect of Specimen Width on Tensile Strength of 2-D Braid LLL ........... 18

Effect of Specimen Width on Tensile Strength of 2-D Braid LSS ........... 18

Effect of Specimen Length on Tensile Strength of 2-D Braids ................ 18

Tensile Strength of Baseline, Dogbone and Net-Shape 2-D

Braided Specimens ........................................................................................ 20

Transverse Tension Strength and Nominal Strain for 2-DBraided Materials .......................................................................................... 20

Summary of Longitudinal Tension Strengths and NominalStrains of Stitched Uniweave Materials ..................................................... 21

Comparison of Longitudinal Tension Strengths and NominalStrains of 3-D Woven Materials ................................................................ 22

Open Hole Specimen Configuration .......................................................... 24

Comparison of Gross, Net and Corrected Stress in SLL and LLS

1/8" Thick Specimens with a 3/8" Diameter Hole .................................. 26

Comparison of Open Hole Tensile Strength in SLL and LLS 1/8"

and 1/4" Thick Specimens with a 3/8" Diameter Hole .......................... 26

Effect of Hole Diameter on



Tension Strength of SLL Specimens ........... 27

Tension Strength of LLS Specimens ........... 28

Tension Strength of LLL Specimens ........... 28

Effect of Hole Diameter on Tension Strength of LSS Specimens ........... 29

Effect of Hole Diameter on Open Hole Tension Strength ofStitched-Uniweave Materials ....................................................................... 30

Open Hole Tension Strength Data for 3-D Woven Materials ................. 31

Effect of Hole Diameter on Open Hole Tension Strength of 3-DWoven Materials OS-1 and OS-2 ................................................................. 32

Effect of Hole Diameter on Open Hole Tension Strength of 3-DWoven Materials LS-1 and LS-2 .................................................................. 32

Effect of Hole Diameter on Open Hole Tension Strength of 3-DWoven Materials TS-1 and TS-2 .................................................................. 33

Modified IITRI Specimen and NASA Short Block Specimen ................. 35

Sandwich Column Specimen, Zabora Fixture and Boeing OHCFixture ............................................................................................................ 36

vii

Figure 7.1.c

Figure 7.2

Figure 7.3

Figure 7.4

Figure 7.5

Figure 7.6.a

Figure 7.6.b

Figure 7.6.c

Figure 7.6.d

Figure 7.7

Figure 7.8

Figure 7.9

Figure 7.10

Figure 8.1

Figure 8.2.a

Figure 8.2.b

Figure 8.2.c

Figure 8.2.d

Figure 8.3.a

Figure 8.3.b

Figure 8.3.c

Figure 8.3.d

Figure 8.4.a

Figure 8.4.b

NASA ST-4 or Boeing CAI Specimen and Boeing OHC or

Zabora Fixture Specimen ............................................................................. 36

Test Section Length Effect on Compression Strength in NASA

Short Block Test Configuration ................................................................... 37

Test Section Length Effect on Compression Strength in modified

IITRI Test Configuration .............................................................................. 38

Test Section Length Effect on Compression Modulus in NASA

Short Block and modified IITRI Test Configurations .............................. 38

Compression Modulus of 2-D Braided Materials ..................................... 39

Compression Strength and Nominal Strain of SLL Braid ....................... 40

Compression Strength and Nominal Strain of LLS Braid ....................... 40

Compression Strength and Nominal Strain of LLL Braid ...................... 40

Compression Strength and Nominal Strain of LSS Braid ........................ 41

Deviation from Mean Strength for Unnotched Compression TestMethods .......................................................................................................... 46

Mean Strength CoVs for Unnotched Compression TestMethods .......................................................................................................... 47

Deviation from Mean Modulus for Unnotched CompressionTest Methods .................................................................................................. 47

Mean Modulus CoVs for Unnotched Compression TestMethods .......................................................................................................... 47

NASA 1142 Specimen Configuration ......................................................... 49

Comparison of Open Hole Compression Strength for VariousTest Methods of SLL Materials ................................................................... 50

Comparison of Open Hole Compression Strength for VariousTest Methods of LLS Materials ................................................................... 50

Comparison of Open Hole Compression Strength for VariousTest Methods of LLL Materials .................................................................. 50

Comparison of Open Hole Compression Strength for VariousTest Methods of LSS Materials ................................................................... 51

Comparison of Coefficient of Variations for Open Hole

Compression Test Methods of SLL Materials .......................................... 51


Compression Test Methods of LLS Materials ........................................... 51


Compression Test Methods of LLL Materials .......................................... 52


Compression Test Methods of LSS Materials ........................................... 52

Effect of Hole Diameter on Open Hole Compression Strength of2-D Braided Materials SLL ........................................................................... 54

Effect of Hole Diameter on Open Hole Compression Strength of2-D Braided Materials LLS ........................................................................... 55

VIII

Figure 8.4.c

Figure 8.4.d

Figure 8.5

Figure 8.6

Figure 8.7

Figure 8.8

Figure 8.9

Figure 8.10

Figure 9.1

Figure 9.2

Figure 9.3

Figure 9.4

Figure 9.5

Figure 9.6

Figure 9.7

Figure 10.1

Figure 10.2

Figure 11.1a

Figure 11. lb

Figure 11. lc

Figure 11.2

Figure 11.3

Figure 11.4.a

Figure 11.4.b

Figure 11.5

Effect of Hole Diameter on Open Hole Compression Strength of2-D Braided Material LLL ............................................................................ 55

Effect of Hole Diameter on Open Hole Compression Strength of2-D Braided Material LSS ............................................................................. 56

Comparison of Mean Coefficient of Variation for all Stitched

Uniweave Open Hole Compression Tests ................................................. 57

Comparison of 1/4" Open Hole Compression Strength andNominal Strains for Stitched Uniweave Materials ................................... 57

Effect of Hole Diameter on Open Hole Compression Strength ofStitched Uniweave Materials ....................................................................... 58

Comparison of 1/4" Open Hole Compression Strength for 3-DWoven Materials ............................................................................................ 59

Normalized Mean Deviations for Open Hole Compression TestMethods in 2-D Braided Materials .............................................................. 60

CoVs for Open Hole Compression Test Methods in 2-D BraidedMaterials ......................................................................................................... 61

Rail Shear Specimen and Compact Shear Specimen ................................ 63

Comparison of Shear Modulus by Various Test Methods for 2-DBraided Materials .......................................................................................... 64

Comparison of Shear Strength Various Test Methods for 2-DBraided Materials .......................................................................................... 65

Shear Modulus of Stitched Uniweave Materials ...................................... 66

Shear Modulus of 3-D Woven Materials with Rail Shear and

Compact Shear Specimen Methods ............................................................ 67

Mean Deviations for In-plane Shear Test Methods .................................. 68

CoVs for In-plane Shear Test Methods ...................................................... 68

Comparison of Net, Gross and Corrected Stress for Filled HoleTension Test of SLL Braid ............................................................................ 70

Comparison of Open and Filled Hole Tension Strength Data for2-D Braided Material ..................................................................................... 70

Baseline Dimensions for Stabilized Single-Shear Specimen ................... 72

Baseline Dimensions for Unstabilized Single-Shear Specimen .............. 72

Baseline Dimensions for Double-Shear Specimen .................................... 73

Effect of W/D and e/D on Stabilized Single Shear Bearing

Ultimate Strength of 2-D Braided Materials SLL and LLS ...................... 74

Effect of e/D on Unstabilized Single Shear Bearing Ultimate

Strength of 2-D Braided Materials SLL and LLS ...................................... 75

Effect of W/D and e/D on Double Shear Bearing Ultimate

Strength of 2-D Braided Materials SLL ...................................................... 75

Effect of W/D and e/D on Double Shear Bearing Ultimate

Strength of 2-D Braided Materials LLS ...................................................... 76

Comparison of all Bearing Tests with W/D=6 and e/D=3 for 2-

Ix

Figure 12.1

Figure 12.2

Figure 12.3

Figure 12.4

Figure 13.1

Figure 13.2

D Braided Materials ...................................................................................... 76

Interlaminar Tension C-Shape Specimen .................................................. 79

Interlaminar Tension L-Shape Specimen ................................................... 79

Interlaminar Tension Strength Measured with C-Shape

Specimen ......................................................................................................... 80

Interlaminar Tension Strength Measured with L-Shape

Specimen ......................................................................................................... 81

Short Beam Shear and Compression Interlaminar Shear

Specimens ....................................................................................................... 82

Interlaminar Shear Strength Measured with Short Beam Shear

and Compression Interlaminar Shear Test Methods ............................... 83

X

Table 2.1

Table 2.2

Table 2.3

Table 3.1

Table 4.1

Table 4.2

Table 4.3

Table 4.4

Table 4.5

Table 5.1

Table 5.2

Table 5.3

Table 5.4

Table 5.5

Table 6.1

Table 6.2

Table 6.3

Table 6.4

Table 7.1

Table 7.2

Table 7.3

Table 7.4

Table 7.5

Table 7.6

List of Tables

Description of 2-D braided Co .mposites Architectures .................................. 2

Description of Stitched Uniweave Materials ................................................... 3

Description of 3-D Interlock Woven Materials ............................................... 4

Summary of Normalized Thicknesses ............................................................. 7

Strain Gage Description ...................................................................................... 10

2-D Braid Longitudinal Modulus Measurements .......................................... 12

2-D Braid Transverse Modulus Measurements .............................................. 13

3-D Weave Longitudinal Modulus Measurements ........................................ 13

3-D Weave - Transverse Modulus Measurements ......................................... 14

Test Matrix for Tension Test Program .............................................................. 16

Summary of Tension Properties of 2-D Braided Materials ........................... 19

Summary of Transverse Tension Properties of 2-D Braided

Materials ............................................................................................................... 20

Summary of Longitudinal Tension Properties of Stitched Uniweave

Materials ............................................................................................................... 21

Summary of Longitudinal Tension Properties of 3-D Woven

Materials ...................................... :........................................................................ 22

Test Matrix for Open Hole Tension Test Program ......................................... 25

Mean Stress and CoV for Open Hole Tension Tests of 2-D Braided

Materials ............................................................................................................... 29

Mean Strength and CoV for Open Hole Tests of Stitched-Uniweave

Materials ............................................................................................................... 30

Mean Strength and CoV for Open Hole Tests "of 3-D Woven

Materials ............................................................................................................... 31

Test Matrix for Compression Test Program .................................................... 35

Summary of Longitudinal Compression Properties for 2-D Braid

Materials ............................................................................................................... 41

Sandwich Column Compression Properties for 2-D Braid

Materials ............................................................................................................... 42

Summary of Transverse Compression Properties for 2-D Braid

Materials Using Modified IITRI Test Method ................................................. 42

Summary

Uniweave

Summary

Uniweave

of Transverse Compression Properties for Stitched

Materials ............................................................................................ 43

of Transverse Compression Properties for Stitched

Materials Using the Modified IITRI Test Method ....................... 44

xI

Table 7.7

Table 7.8

Table 7.9

Table 8.1

Table 8.2

Table 8.3

Table 8.4

Table 8.5

Table 9.1

Table 9.2

Table 9.3

Table 9.4

Table 9.5

Table 9.6

Table 10.1

Table 10.2

Table 11.1

Table 11.2

Table 11.3

Table 11.4

Table 12.1

Table 12.2

Table 12.3

Table 13.1

Table 13.2

Table 13.3

Table 14.1

Table 14.2

Summary of Longitudinal Compression Properties for 3-D Woven

Materials ............................................................................................................... 44

Summary of Longitudinal Compression Properties for 3-D Woven

Materials the Using Modified IITRI Test ......................................................... 45

Mean Deviations A---xnand CoVs for Unnotched Compression Test

Methods ................................................................................................................ 46

Test Matrix for Open Hole Compression Test Program ................................ 48

Summary of Open Hole Compression Test Results for 2-D Braided

Materials ............................................................................................................... 53

Summary of Open Hole Compression Test Results for Stitched

Uniweave Materials ........................................................................................... 57

Summary of Open Hole Compression Test Results for 3-D Woven

Materials ............................................................................................................... 58

Mean deviations AXknand Axn for Open-Hole Compression Test

Methods ................................................................................................................ 60

Test Matrix for Shear Properties ....................................................................... 62

Summary of Tube Torsion Test Results for 2-D Braids ................................. 64

Summary of Rail Shear and Ifju Fixture Test Results for 2-D Braids ........... 64

Shear Properties of Stitched Uniweave Materials .......................................... 65

Shear Properties of 3-D Woven Materials ........................................................ 66

Normalized Mean Deviations AXn for Shear Test Methods ......................... 68

Filled Hole Tension Test Program .................................................................... 69

Filled Hole Tension Test Program .................................................................... 70

Bolt-Bearing Test Matrix .................................................................................... 71

Stabilized Single Shear Bearing Ultimate Strength Results for 2-D

Braids .................................................................................................................. 77

Unstabilized Single Shear Bearing Ultimate Strength Results for 2-D

Braids .................................................................................................................. 77

Double Shear Bearing Ultimate Strength Results for 2-D Braids ................. 77

Interlaminar Tension Test Matrix ..................................................................... 78

Interlaminar

Interlaminar

Interlaminar

Interlaminar

Interlaminar

Interlaminar

Interlaminar

Tension Strength Measured with C-Shape Specimen ............. 80

Tension Strength Measured with L-Shape Specimen ............. 81

Shear Test Matrix ......................................................................... 83

Shear Strength in 2-D Braided Materials .................................. 84

Shear Strength in 3-D Woven Materials ................................... 84

Toughness Test Matrix ................................................................ 86

Toughness Test Results ............................................................... 87

XII

1. Introduction

Carbon/Epoxy composites made from textile fiber preforms manufactured with a

Resin-Transfer-Molding (RTM) process have potential for reducing costs and increasing

damage tolerance of aerospace structures. While many standardized test methods are

available for conventional tape laminates, these may not be directly applicable to textile

composites. The main concern is that textile composites tend to be less homogeneous

than conventional tape laminates. Thus, it was anticipated that some scaling effects may

be observed and that larger size specimens may be required. The objective of the task

described in this report was to evaluate existing test methods for measuring stiffness

and strength properties of specimens loaded in tension, with and without holes,

compression, with and without holes, shear and bolt bearing, and to make

recommendations for changes in the test configuration. A secondary objective of this

task was to increase the database of mechanical properties of textile composites in order

to assist in the development of analytical models and the assessment of the benefits of

textile composites for future applications.

As a result of a NASA Advanced Composite Technology (ACT) Program Steering

Committee recommendation, this program was initiated out of the Mechanics of

Materials Branch at the NASA Langley Research Center. This program was assembled

to address critical technology needs for the ACT Program and other NASA funded

programs.

This report describes work accomplished under Contract NAS1-19247 from the

National Aeronautics and Space Administration, Langley Research Center, Hampton

VA. Mr Clarence C. Poe Jr., NASA LaRC, was the NASA Technical Monitor. Bill Fedor

of Boeing Aerospace Operations was the program manager. The Structures Technology

organization of the Boeing Defense & Space Group, Helicopters Division was

responsible for completing this task. Most of the specimen manufacturing was

performed by Boeing Defense and Space Group Research and Engineering (Seattle,

WA), while all the material testing was conducted at Integrated Technologies, Inc.

(Intec, Bothell, WA.) Dr John Masters of Lockheed Engineering & Science contributed

Section 4 of this report.

The objectives of this report are to summarize all the strength and stiffness

properties measured for the various textile composites investigated, to assess the

performance of various test methods and, where possible, to provide recommendations

on preferred test configurations for textile composites.

2. Material Systems

Three different types of textile composites were utilized in this investigation: 2-

Dimensional triaxial braids, stitched uniweave fabric and 3-Dimensional interlock

woven fabric. Textile preforms were procured from their respective vendors mentioned

below. All preforms were Resin Transfer Molded (RTM) and cured at Boeing Defense

and Space Group, Seattle, WA. Hercules AS4 fibers is used for all fabrics. The resin

system used for all materials is Shell RSL-1895, a two-par_ epoxy system with Shell

Epon Curing Agent W formulated for RTM to have comparable properties to Hercules

3501-6 resin system. All details of the manufacturing process can be found in NASA CR

191505, "Resin Transfer Molding of Textile Composites ," (Ref. 1).

2.1 2-D Braided Composites

The 2-D braided fabric contains two types of tows, the longitudinal (axial, or 0 °) tow

and the braided (or bias) tows oriented at angle 0 to the axial tow as illustrated in Figure

2.1. The braid pattern used is a 2X2 pattern, meaning that each braided tow goes over

and under two tows at a time. All preforms were manufactured by Fiber Innovations

Inc., Norwood, MA.

Three important braid parameters are braid angle, yarn size (measured in K, where

1K equals 1000 filaments), and proportion of fixed (0 °) yarns. The four braids in Table

2.1 were designed to give three combinations of these parameters so that changes to

mechanical properties due to changes in these parameters can be determined. The tow

sizes were different for the first and third braids (SLL and LLL), the braid angles were

different for the second and third braids (LLS and LLL), and the percentage of fixed

yarns were different for the second and fourth braids (LLS and LSS). The 46% of axial

tows for the first three braids is typical of a braid optimized for predominantly

longitudinal loading. The 12% of axial tows for the fourth braid (LSS) is typical of a

braid optimized for predominantly shear loading. The braids marked "-2" and "-3" are

variations of the basic architectures used only in the interlaminar properties tests.

Name

Table 2.1 Description of 2-D braided Composites Architectures

LSS

LongitudinalTow Size

Braided Tow

Size% Longitudinal

Tow

SLL 30 K 6 K 46

LLS 36 K 15 K 46

LLL 75 K 15 K 46

12

SLL-2

6K

15K

30K

15 K

LLS-2

15K

3K

12K

6KLLS-3

46

47

47

Braid

Angle [°]I

7O

Unit Cell

Width [in]

0.458

45 0.415

70 0.829

45

7O

45

45

0.415

0.349

0.349

0.262

Unit Cell

Length [in]

0.083

0.207

0.151

0.207

0.063

0.175

0.131

2

The unit cell dimensions vary considerably and are typically quite large. The unit

cell width is defined as twice the spacing of the axial tows, while the unit cell length is

twice the distance, along an axial tow, between the intersections of an axial tow and a

+0 tow (these factors of 2 are due to the fact that this is a 2X2 pattern).

Braider Yarn

Unit Cell IHeight

Figure 2.1

Axial Yarn

Unit Cell Width

Braid Angle

Illustration of 2-D Triaxial Braid Configuration.

2.2 Stitched Uniweave Composites

Stitched uniweave fabric consists of several plies of unidirectional graphite fibers

woven with a light E-Glass tow (8 picks per inch). This fabric was produced by Textile

Technologies Inc. (Style 4003-PW). Several of these layers were then stitched together

through the thickness by Cooper Composites. All the materials used here have a quasi-

isotropic [+45/0/-45/9016s layup. As shown in Table 2.2, the variables examined relate

to the stitching process itself. The effects of stitch material, pitch, spacing (between rows

of stitches) and size are investigated with the five different configurations shown in

Table 2.2.

Table 2.2 Descri _tion of Stitched Uniweave Materials

Name Stitch Material Stitches per inch Stitch Spacing [in] Stitch Tow Size

SU-1 $2 Glass 8 0.125 3 K

SU-2 $2 Glass 8 0.125 6 K

SU-3 Kevlar 29 8 0.125 6 K

SU4 Kevlar 29 4 0.250 6 K

SU-5 Kevlar 29 8 0.125 12 K

3

2.3 3-D Interlock Woven Materials

Interlock woven fabric is a three-dimensional fabric in which yarns are interlaced

through the thickness to improve interlaminar properties over conventional laminates.

The warp tows run parallel to the weaving machine direction, with the weft tows

running perpendicular to these. The interlock tows wrap around the weft tows in

parallel to "the warp tows. Three interlock configurations with different tow sizes were

used as described in Table 2.3 and illustrated in Figure 2.2. All preforms were produced

by Textile Technologies Inc. (TTI).

Table 2.3 Description of 3-D Interlock Woven Materials

Name

OS-1

OS-2

TS-1

TS-2

LS-1

LS-2

Description

Through -the-thickness

orthogonai interlock

Through-the-thickness

angle interlock

Layer-to-layer interlock

Warp Tow

24 K (59%)

12 K (58%)

24 K (57%)

12 K (56%)

24 K (58%)

12 K (57%)

Weft Tow

12 K (33%)

6 K (37%)

12 K (33%)

6 K (38%)

12 K (34%)

6 K (36%)

Weaver Tow

6 K (7.4%)

3 K (6.1%)

6 K (9.8%)

3 K (5.8%)

6 K (6.8%)

3 K (5.9%)

Figure 2.2

Weft (90 °) Warp (0 °)

T-t-t Orthogonal T-t-t Angle Layer-to layer

Depiction of 3-D Interlock Woven Materials.

4

3. Data Reduction Techniques

The different techniques used to analyze the experimental data described in the

following chapters are documented here. These include specimen fiber volume

measurement and thickness normalization, strength and stiffness properties calculation,

and open hole strength analysis.

3.1 Fiber Volume Measurements

Resin digestion tests were performed on all panels used in this investigation to

determine fiber volume fraction and void content. All resin digestion procedures are

carried out using a microwave technique. The method consists of obtaining both the dry

and submerged weight of a 0.5 inch by 0.5 inch composite specimen to determine its

specific gravity. The specimen is placed in a reaction pressure vessel to which 25 to 30

ml of nitric acid is added. The reaction vessel is sealed and placed in a microwave oven

for heating. The digestion is run in four stages, with each consecutive stage ramping to

a higher pressure. Running the experiment at higher pressure enables the temperature

to increase without boiling the acid. Upon complete digestion of the resin, the fibers are

filtered from the acid and rinsed with water and acetone. After drying, the carbon fibers

are weighted and their volume fraction determined. The fiber and resin densities used

in the calculation were 1.80 g/cm 3 and 1.18 g/cm3 respectively.

3.2 Thickness Normalization

One of the first difficulties encountered when examining the experimental data was

the fact that there is some scatter in fiber volume fraction from plate to plate. This is

especially true of the 2-D braided materials. In order to calculate stress and modulus

from the data, a method to normalize these results had to be chosen. Typically, when

dealing with tape or fabric laminates, a normalized thickness corresponding to a given

fiber volume is determined and kept constant for all calculations. A similar approach is

used in the present investigation. As illustrated in Figure 3.1, volume fraction and

thickness data was obtained for each material system. The mean thickness and fiber

volume was determined across all panels of a given material and nominal thickness. In

general, the scatter was always much higher for the 2-D braided materials than for the

other material systems. The thickness corresponding to a 60% volume fraction was

then calculated and used to calculate all stresses and moduli for that material form.

The resulting thicknesses are listed in Table 3.1. Note that for the 2-D braided

material, two thicknesses were used to look at the influence of this parameter. When

referring to these materials in the text of this report, their nominal values of 1/8" and

1/4" will often be used for simplicity, alfl_ough the actual value is somewhat different.

5

Figure 3.1

CO

O

u-

E

O

U_

0.700 SLL 2-D Braid ArchitectureT

0.600 _ [] 13 []

0.500

O.4O0

0.300

0.200

0.100

0.000

0.102

, ! , I , I , I , I

0.104 0.106 0.108 0.110 0.112

Thickness [in]

O

I.J-

E._=O>$

..13

U-

0.700

0.600

0.500

0.400

0.300

0.200

0.100

LLS 2-D Braid Architecture

_ __"_____ £_J1_m-J'l [] n

0.000 .... I .... ! .... I , ,, , , I

0.100 0.105 0.110 0.115 0.120

Thickness [in]

t.-.9

IJ_

E

iT

0.700

0.600

0.500

0.400

0.300

0.200

0.100

0.000

0.220

SU-1 Stiched Uniweave CompositeIN Ilmu_lmlmll_n "- l,

, I , I , I

0.221 0.222 0.223

Rmg

, I

0.224

Thickness [in]

Example of Relationship between Fiber Volume Fraction and Thickness

for SLL, LSS and SU-1 Specimens.

6

Table 3.1 Summary of Normalized Thicknesses

Name Thickness Name

linl

SLL 0.110 or 0.215

LLL 0.114 or 0.229

LLS 0.112 or 0.220

LSS 0.111 or 0.215

LS-1 0.226

LS-2 0.230

OS-1 0.234

OS-2 0.226

TS-1 0.237

TS-2 0.228

Thickness

[inl

SU-1 0.247

SU-2 0.265

SU-3 0.261

SU-4 0.241

SU-5 0.274

3.3 Stress. Modulus and Poisson's Coefficient Calculation

The first issue that arises when reducing material testing data from load to stress is

the question of how to define thickness. One observation made when analyzing the data

generated in this test program was the higher than usual scatter in some of the results.

Although this is somewhat inherent to the materials tested here, it was found that part

of that scatter was due to the use of actual measured specimen thickness because of the

variability in thickness and fiber volume fraction from panel to panel. Therefore, in this

report, ultimate stress is defined as the specimen ultimate load divided by the specimen

actual width and nominal thickness calculated in the previous section:

P(l -

W t_om

where P is the load, w the specimen width and tnom the nominal thickness

The specimen modulus was calculated by performing a linear regression of load

versus axial strain The axial strain range used in the calculation is 1000 to 3000

microstrains. The specimen actual width and nominal thickness are used in the

calculation. Similarly, the Poisson's coefficient was calculated by performing a linear

regression of transverse versus axial strain over the same range of axial strain.

3.4 Open-Hole Data

When analyzing data from an open hole test, there are several ways to calculate and

report stress at failure. The first approach is to use the gross stress defined as load

divided by the cross-section area of the specimen away from the hole.

7

P(_gross -

w tno m

The second way is to use net stress by using the section area through the hole.

P(_net = where d is the hole diameter

(W - d) tno m

Another way to reduce the data is to correct the gross stress with the width correction

factor described in Ref. 2. This factor is defined as the ratio of stress concentration factor

in the finite width coupon to stress concentration factor for a hole in an infinitely wide

plate. Although this factor should vary with the elastic constants of the material, that

correction factor is fairly small for the type of specimens typically used. Thus, it is

customary to use the correction factor developed for a quasi-isotropic laminate for all

laminates.

(loo _ W

O0ro,,For example, in the following chapters, testing of specimens with w/d = 4, 6 and 8 will

be performed. Thus, for these specimens, the correction factor is equal to 1.076 for

w/d=4, 1.031 for w/d=6 and 1.017 for w/d=8.

In order to analyze the data for the effect of hole size, a procedure similar to the Mar-

Lin fitting technique is used (Ref. 3). After obtaining the mean strength for each hole

diameter, a best fit curve was calculated by performing a linear regression of the

logarithm of strength versus the logarithm of diameter:

Iog(_ = a Iogd + b or (5 = s d a with s = 10 b

The parameter a can be roughly interpreted as the material sensitivity to hole diameter.

4. Strain Gage Size Sensitivity Study

Significant variations in displacement field homogeneity have been identified in

textile composite specimens through the use of Moir6 interferometry. Uniaxial tension

test results indicate, for example, that local strains may vary by as much as a factor of

two within the unit cells of laminates formed from 2-D triaxially braided preforms (Ref.

4). Test specimens must, therefore, be designed to encompass representative volumes of

material within their test sections to obtain characteristic measures of mechanical

response. The size and type of instrumentation used plays a similarly critical role in

obtaining accurate measurements.

A series of tensile tests were conducted to determine the sensitivity of strain

measurements to the size of the strain gage. The objective of this study was to establish

a database which will be used to develop guidelines for the instrumentation of textile

composites. Descriptions of the test specimens and test procedures employed in the

study and the strain gages investigated are presented in the following sections. They are

followed by a review of the test results.

4.1 Test Specimens and Procedure,#.

Samples of the four 2-D triaxial b_'aids and the six 3-D weaves described earlier in

this report were loaded in uniaxial tension. Strains in both the longitudinal direction

(parallel to the 0 ° yarns) and the transverse direction (perpendicular to the 0 ° yarns)was measured.

Forty specimens were tested in the program. Because of limited quantities of

material, only four specimens, 2 axial and 2 transverse, were used for each material

type. The longitudinal or axial tension specimens were 1.5 in. wide and 10.0 in. long.

The transverse tension specimens were 1.5 in. wide and 7.0 in. long. All specimens

tested in this study were nominally 0.250 inches thick. Strain measurements were made

over a 3 inch long section centered along the length of the specimen.

All tests were conducted on a 50 Kip servo-hydraulic test machine. It was

programmed to run in displacement control at a ramp rate of 0.01 in/min. Strain was

monitored throughout the test. Loading was halted at 3250 microstrain and the

specimen was unloaded. Each specimen was loaded three times in this manner. Load,

displacement, and strain were continuously recorded via a data acquisition system

which monitored each channel once a second.

4.2 Strain Gaoes Investioated.

Six gage types were investigated in this study. They were chosen to provide a range

of gage lengths from 0.125 inch to 0.500 inch, and widths ranging from 0.062 inches to

0.500 inches. Three of the gages featured square grids; three had rectangular grids. The

9

length-to-width ratio of the rectangular gageswas approximately 2 to 1. A total of ninestrain gages (three of each type) were mounted on each specimen; six on one side andthree on the other. Table 4.1 lists all gages used and their dimensions, resistance andcost per package of five gages.

Table 4.1Strain GageDescription

Strain Gage Type Gage Dimensions Resistance Price

[in] [Ohmsl {S/Pkg.]i

EA-06-125BZ-350 0,125 x 0.062 350 17

EA-06-125AD-120 0.125 x 0.125 120 17

CEA-06-250UN-350 0.250 x 0.120 350 30

EA-06-250AE-350 0.250 x 0.250 350 32

CEA-O6-500UW-350 0.500 x 0.180 350 48

EA-O6-500AE-350 0.500 x 0.500 350 80

4.3 Experimental Results.

The strains recorded by each gage mounted on the specimen were used to compute

modulus. The resulting moduli were then averaged together. Standard deviations and

coefficients of variation were also computed to measure the scatter in the data.

The longitudinal and transverse tension tests results obtained for the 2-D braid

materials are given in Tables 4.2 and 4.3, respectively. Test results obtained for the 3-D

weave materials are listed in Tables 4.4 and 4.5. The tables list the average moduli

measured for each gage type, i.e. the average of three gages per gage type, and the

standard deviations of these measurements. The coefficients of variation of these

measurements are given in parenthesis in the tables. These data have not been

normalized to a common fiber volume or thickness. The thicknesses of the individual

specimens are listed in Tables 4.2-4.5.

In most cases, the materials' moduli were computed over the 1000 to 3000

microstrain region of the stress-strain curves. The slopes of the curves were established

through linear regression of the data. The two exceptions were the 2-D braid laminate

LLL and the 3-D weave laminate LS1. They both apparently developed damage at

approximately 2500 microstrain. The moduli in these cases were computed over

narrower ranges since the gages reflected the damage development.

A review of these test results is necessarily restricted to qualitative assessments due

to the limited amount of data available. Only three replicate gages could be mounted on

the specimens and only two specimens were available for each material type.

Qualitative assessments are, however, possible and general trends in the data are

apparent.

10

4.4 2-D Braided Materials

A review of the data obtained for the four braided laminates indicates that the

reproducibility of the measurements is greatly increased as the gage length increases.

This is illustrated in Figure 4.1 which plots the coefficient of variation of the moduli

measurements obtained for each gage type versus the gage length. Both the longitudinal

and transverse test results are displayed in the figure. The gage length in this case has

been normalized by dividing the strain gage's length by the material's unit cell length.

A vertical line marks the point at which the strain gage length is equal to the unit cell

length. As the figure demonstrates, the data's coefficient of variation greatly decreases

when the strain gage length exceeds the length of material's unit cell. In fact, the

coefficient of variation exceeded 5% (as indicated by the horizontal Line in the figure) in

only two of the twenty-four cases in which the gage was longer than the unit cell.

25.00

Figure 4.1

A

20.00¢-om

i..15.00

>

c_ 10.oo

0(3 5.O0

; .... .I .... I .... I . . •

Gage Length =

Unit Cell Height

[]

oH•

Arn

• Gage: 125 BZ (.125 x .062)

[] Gage: 125 AD (,125 x ,125)

• Gage: 2S0 UN (.250 x .120)

z_ Gage: 250 AE (.250 x .250)

• Gage: 500 UW (.SO0 x .180)

O Gage: SO0 AE (.SO0 x .500

[]

z_Coefficient of Variation = 5 %

m o i0

A0.00 .... ...... Y--n .... = .... m .... m ....

0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0

Normalized Gage Length (Gage Length/Unit Cell Length)

Coefficient of Variation of Moduli for each Gage Type.

While the coefficient of variation of the moduli measurements decreased with

increasing gage length, there was no clear pattern to changes in mean moduli as strain

gage length increased. Although there were several cases in which the moduli were

lower as gage length increased, the change in moduli that accompanied an increase in

strain gage length was within the scatter of the data in a majority of cases. It was

apparent, however, that changes in modulus were small (i.e. less than 5%) when the

gage length was increased beyond the unit cell length.

The data also permitted a comparison of the effect of strain gage width on the

measurements. As in strain gage length sensitivity comparison discussed above, in a

11

majority of cases the change in moduli that accompanied an increase in strain gage

width was within the scatter of the data. However, when comparisons were possible,

i.e. when changes in modulus exceeded the coefficients of variation of the moduli, the

data indicated that increasing gage width decreased modulus. These changes exceeded

5% in several cases. No relationship between gage dimensions and unit cell dimensions

was discerned, however.

4.5 3-D Woven Materials

Many of the trends noted for the braided laminates were also apparent when the

woven laminate data listed in Tables 4.4 and 4.5 were examined. Scatter in the data, as

monitored by the coefficient of variation, again decreased as gage length increased.

Almost half of the modulus measurements made using the shortest, 0.125 in., gages had

coefficients of variation in excess of 5%. The number of instances in which the

coefficients of variation exceeded this value decreased markedly as gage length

increased to 0.250 in. and 0.500 in.

Instances in which the measured modulus decreased as gage length increased were

also evident in the woven laminate test results. However, as noted above for the braided

laminates, the change in moduli that accompanied an increase in strain gage length was

within the scatter of the data in a majority of cases. Increasing strain gage width had a

similar effect on the measured moduli.

Table 4.2 2-D Braid Longitudinal Modulus Measurements

Material Thick Modulus |Msi]

125 BZ 125 AD 250 UN 250 AE 500 UW 500 AE

8.78 + 0.83 9.25 + 0.28 8.74 + 0.34

(9.5%) (3.0%) (3.9%)

8.75 + 0.40 8.86 + 0.30 8.58 + 0.18

(4.6%) (3.4%) (2.0%), ii

8.61 __+0.88 9.14 __+0.67 9.06 + 0.22

(10.2%) (7.3%) (2.4%)

9.47 +__0.64 8.50 + 0.22 8.67 + 0.15

(6.8%) (2.6%) (1.7%)

•222 10.06 + 0.82 9.81 + 0.45 - 9.52 +-0.34(8.2%) (4.6%) (3.6%)

SLL

[in]

.219

SLL

LLL

LLL

LLS

LLS

LSS

LSS

.220

.218

.230

.252

.221

.223

8.85 + 0.96 8.87 + 0.25 8.96 + 0.08

(10.8%) (2.8%) (1.0%)

4.79+0.14 4.77+0.15 4.92+0.07

(2.9%) (3.1%) (1.4%)

4.52 + 0.36 4.50 + 0.08 - 4.34 + 0.02

(8.0%) (1.7%) (0.5%)

12

Table 4.3 2-D Braid Transverse Modulus Measurements

Material

SLL

SLL

LLL

LLL

LLS

LLS

LSS

LSS

Thick

[in]

.223

.223

.221

.223

.222

.250

.223

.222

Modulus [Msil

125 BZ 125 AD 250 UN 250 AE 500 UW

7.63 + 0.80 6.41 _+0.81 - 6.89 + 0.10

(10.5%) (12.6%) (1.5%)

5O0 AE

6.84 + 1.0 6.32 _+0.28 6.29 _+0.(_5

(14.6%) (4.4%) (1.0%)

8.06 + 0.65 7.82 - 6.98 ± 0.90

(8.0%) (12.9%)

7.03 ± 3.51 - - 6.41 ± 0.21

(50.0%) (3.3%)

3.22 + 0.20 - 2.94 ± 0.28

(6.2%) (10.0%)

- 2.68 +_0.53 2.51 ± 0.15 -

(19.8%) (6.0%)

6.64 ± 0.69

(10.4%)

2.80 + 0.12

(4.0%)

2.98 +_0.03

(1.0%)

3.12 __+0.17 - 3.33 -+0.02

(5.4%) (0.6%)

2.79 ± 0.11

(3.9%)

3.07 ± 0.22 3.22 + 0.12 - 3.21 + 0.04

(7.2%) (3.7%) (1.2%)

Table 4.4 3-D Weave Longitudinal Modulus Measurements

Material Thick Modulus [Ms±]

TS1

TS1

TS2

TS2

LS1

LS1

LS2

LS2

OS1

OSI

OS2

OS2

[in]

.230

.230

.226

.227

125 BZ 125 AD 250 UN 250 AE

11.59 ± .41 12.04 _+.84

(3.5%) (7.0%)

12.36 ± .51 12.27 + .09

(4.0%) (0.7%)

11.42 ± .43 - 10.49 __+.78

(3.8%) (7.4%)

11.82 + .55 11.35 + .04

(4.7%) (0.4%)

500 UW 500 AE

11.62 + .25

(2.0%)

11.93 + .19

(1.5%)

10.94 + .18

(1.6%)

11.03 ± .10

(0.9%)

.222

.227

.231

.228

.228

.226

.230

.230

13.06 ± .42 13.32 ± .63

(3.2%) (4.7%)

13.89 ± 3.54 - 13.03 -+ .40

(25.0%) (3.1%)

- 12.14 +__.27 12.26 +__.06

(2.2%) (0.5%)

12.10 + .62 - 11.83 + .43

(5.1%) (3.6%)

11.28 __+.59 12.71 __+.34

(5.2%) (2.7%)

11.73 __+.60 - 11.56 -+ .75

(5.1%) (6.5%)

10.69 ± .23 11.07 + .42

(2.2%) (3.8%)

10.62 __+.25 - 10.03 __+.40

(2.4%) (4.(/%)

12.65 ± .32

(2.5%)

12.34 + .26

(2.1%)

11.72 ± .17

(1.5%)

11.28 + 06

(0.5%)

11.41 ± .20

(1.8%)

10.45 + .32

(3.1%)

11.26± .21

(1.9%)°

11.29 + 1.0

(8.9%)

13

Table 4.5 3-D Weave - Transverse Modulus Measurements

Material Th ick Modulus [Msi]

TS1

[in]

.229

125 BZ

6.43 ± .48

(7.5%)

125 AD 250 UN 250 AE

6.53 _+.19

(2.9%)

500 UW 500 AE

6.35 + .06

(1.0%)

TS1 .229

TS2 .224

TS2 .231

LS1 .228

LS1 .223

LS2 .233

LS2 .231

OS1 .229

OS1 .225

OS2 .232

0S2 .232

6.44 + .20

(3.1%)

7.25 + .33

(4.6%)

7.32 + .61

(8.3%)

6.18 _+.29

(4.7%)

6.15 + .42

(6.8%)

6.58 + .61

(9.3%)

6.70 _+.89

(13.3%)

6.91 + .43

(6.2%)

7.17 +_.67

(9.3%)

6.35 + .14

(2.2%)

6.76 _+.15

(2.2%)

7.25 _+.36

(5.0%)

6.41 _+.59

(9.2%)

6.98 + .41

(5.9%)

7.00 + .16

(2.3%)

6.49 + .03

(0.5%)

6.70 + .07

(1.0%)

6.83 + .17

(2.5%)

6.78 + .06

(0.9%)

6.27 + .02

(0.3%)

6.03 + .26

(4.3%)

6.35 + .50

(7.9%)

6.53 + .05

(O.8%)

6.89 + .50

(7.3%)

6.58+ 11

(1.7%)

6.78 + .06

(0.9%)

6.91 + .28

(4.1%)

6.75 _+.08

(1.2%)

6.22 + .07

(1.1%)

6.01 + .09

(1.5%)

6.20 _+.14

(2.3%)

6.21 + .07

(1.1%)

6.14+ .12

(2.0%)

14

5. In-Plane Tension Test Program

The behavior of textile composites under unidirectional tensile loading is examined

in this chapter. Strength, stiffness and Poisson's coefficient are measured. The effect of

specimen width and length is the main focus of the test method evaluation.

5.1 Test Confiouration

The test matrix used for this program is shown in Table 5.1. A total of 156 2-D

braided specimens, 15 stitched uniweave specimens and 18 3-D woven specimens were

used. Specimen configuration effects were studied with the 2-D braided specimens,

while the stitched uniweave and 3-D woven specimens used a single size, 2 inch wide

by 7 inch long.

The basic specimen for this test program is the straight sided coupon described in

ASTM D3039 and illustrated in Figure 5.1. This specimen was used to measure tension

strength, modulus and Poisson's ratio. A dogbone specimen configuration in Figure

5.1b was also used for some of the tests. Beveled fiberglass tabs, with 5 ° taper angle and

0.050 inch thick, were bonded to the straight-sided specimens. The dogbone and

transverse tension specimens were not tabbed since initial tests of such specimens

resulted in failures within the test section. During testing, the specimen ends were

gripped with hydraulic grips and the coupon loaded to failure at a stroke rate of 0.05

inches per minute.

An extensometer with a one inch gage length was used in all tests. The extensometer

was attached at the center of the gage length with rubber bands and hot glue or M-Bond

200. A few specimens experienced extensometer slippage prior to failure, generally

because of local fiber or matrix failure prior to final failure. Most specimens were also

instrumented with longitudinal and transverse 1/2 inch square strain gages

(Measurements Group Inc. EA-06-500AE-350).

F 0.050" Fiberglass Tab, 5° TaperI

Figure 5.1.a

back longitudinal and transverse gages

2.25" _--i_ Length vI_1

Typical Tension Specimen Configuration.

15

Figure 5.1.b

_31" Radius

01

J_7.0"11.5"

Dogbone Tension Specimen Configuration.

Table 5.1 Test Matrix for Tension Test Program.

r .............. III

Gage Section Material Systems I

I Dimensions

Width Length Note SLL SLL LLS LLS LLL LLL LSS LSS Others

[in] [in] 1/8" 1/4" 1/8" 1/4" 1/8" 1/4" 1/8" 1/4" (1)

1.00 3.50 3 3 3 3 3 3 3 3

1.50 5.25 3 3 3 3 3 3 3 3 I

I 2.00 5.50 3 3 3 3

2.00 7.00 3 3 3 3 3 3 3 3 3

2.00 8.50 3 3 3 3

-----2.50 8.75 ..... 3 3-- - 3 3 - 3 - -3 ..... 3 .... 3 ........ I

. 1.60 7.00 Dog-Bone 3 3 3 3

1.50 [ ZOO Net-Shape 3 3 3 3i

-2-_--- ZOO Transverse 3 3 3 3

27 18 27 18 21 12 21 12 33

(1) Five Stitched Uniweave and Six 3-D Woven Materials.

5.2 2-D Braid Materials

5.2.1 Test Section Width, Length and Thickness Effectsv

One issue of interest in the tensile testing was the effect of the specimen width

compared to the unit cell size of the materials. A certain minimum number of unit cells

should be present across the test section to insure a representative failure mode. The

baseline test section used here is 2 inches wide and 7 inches long. Specimens with a

width ranging from 1 to 2.50 inches were tested to detect any sensitivity to width.

Results for the four braid types are shown in Figure 5.2, where strength and

coefficient of variations (CoV) are reported. No clear trend can be identified, either by

looking at the mean values or the CoV. It is interesting to note that the largest unit cell

width is that of the LLL braid at about 0.83 inch and that a one inch wide coupon

16

contains just over one cell. Yet, no difference was observed in strength.

Similarly, no trend can be identified between thin and thick specimen in terms of

scatter. The difference in mean result between thin and thick specimens with a width

greater or equal to 1.5 inch was +2.9% for SLL, +4.4% for LLS, +0.2% for LLL and 0% for

LSS. Since these values are within the results scatter, there appears to be no significant

difference between 1/8" and 1/4" thick specimens.

Finally, results for the SLL and LLS specimens are plotted in Figure 5.3 as a function

of the specimen test section length. No trend in tension strength can be observed in

changing the length from 5.5 to 8.75 inches.

2-D Braid, SLL Architecture 2-D Braid, SLL Architecture140 o_" 1012o 9

..1: .9 8100 ._ 7

L-.

680 _ 560 _

g 40 E 4

i_ 20 ,.-:-_ 2o 1

0.50 1.00 1.50 2.00 2.50 3.00 0 01 1.5 2 2.5

Specimen Width [in]

Figure 5.2.a

Specimen Width [in]

Effect of Specimen Width on Tensile Strength of 2-D Braid SLL.

140

_ 12o

100

_ 80

r-.o

¢-.

I--

2-D Braid, LLS Architecture

6O°

40!

20 i

0"

0.50.... I .... I .... I .... I .... I

1.00 1.50 2.00 2.50 3.00

Specimen Width [in]

Figure 5.2.b

o_ 109

t--o 8,B

76

> 54

¢..

3"° 2

1oo 0


.... I .... I .... I1.5 2 2.5

Specimen Width [in]

Effect of Specimen Width on Tensile Strength of 2-D Braid LLS.

17

140" 120

100

8o60

g 4o_ 20

_ o

2-D Braid, LLL Architecture

0.50 1.00 1.50 2.00 2.50 3.00


._ 108

6i,2

8 o1 1.5 2 2.5

Specimen Width [in] Specimen Width [in]

Figure 5.2.c Effect of Specimen Width on Tensile Strength of 2-D Braid LLL.

..=.r,-

09t-._oct_

140

120

100

8O

60

4O

2O

0

0.50

2-D Braid, LSS Architecture o_ 1

t-O

>"5t"

(1)0o

1.00 1.50 2.00 2.50 3.00

Specimen Width [in] Specimen Width [in]

Figure 5.2.d Effect of Specimen Width on Tensile Strength of 2-D Braid LSS.

140 2-D Braid, SLL Architecture _ 140 2-D Braid, LLS Architecture

100 _ 100

80 _ 80

60 60

40 .o 40

20 #. 200 0 , , I , , I ,, I

2-D Braid, LSS Architecture09876543210

1 1.5 2 2.5

4. 6. 8. 10. 4. 6. 8. 10.

Figure 5.3

Gage Section Length [in] Gage Section Length [in]

Effect of Specimen Length on Tensile Strength of 2-D Braids.

5.2.2 Longitudinal Tension Test Summary

The results from all the tension tests are summarized in Table 5.2. Since it was seen

in the previous section that gage length and width had a minimal influence on the

results, data from all specimen configurations were averaged together for each type of

material. In this table, maximum strain refers to the last strain gage reading prior to

18

failure, while nominal strain is simply the ultimate stress divided by modulus. Because

of the possibility of local damage developing under the strain gage prior to failure, the

maximum strain reading is not always very reliable and shows quite a bit of scatter.

Therefore, it is listed here mostly for reference purpose. In design practice, the value

used is always the nominal strain since materials are assumed to behave linearly to

failure. Results for both thin and thick specimens are listed although there does not

appear to be any significant difference between the two. Poisson's coefficient

measurements were not very reliable in general and showed a very high scatter.

A particularly interesting comparison can be made between the SLL and LLL

specimens where only the longitudinal and bias tow sizes have been changed by a

factor of 2.5. This results in a 20% strength reduction and 5% modulus reduction.

As mentioned above, a dogbone shape coupon was considered as an alternative test

configuration. A strength comparison with the baseline specimens is shown in Figure

5.4. A slightly higher strength is obtained in half the cases, and a slightly lower strength

in the other two. Thus, there does not appear to be a strong reason to prefer the

dogbone specimen which, in addition, is more expensive to prepare.

In all the previous tests, the specimens were cut from large panels. However,. in

certain structural elements, the material does not need to be cut and can be molded to

net shape by folding the dry preform along the edge of the part. This fold results in a

slightly different fiber orientation along the edge of the specimens. A series of tests was

conducted to investigate this effect using a coupon with a 1.5 inch wide by 7 inches long

test section. A strength comparison with the baseline is also shown in Figure 5.4. All

net-shape specimens exhibited a higher strength. Two of the likely reasons for this are

that the fiber architecture is different near the edge with more fibers oriented

longitudinally, and possibly that free-edge stresses are reduced.

Table 5.2 Summary of Tension Properties of 2-D Braided Materials

Property

Strength [ksi]

Nominal Strain [_ts]

CoV [%]

Modulus [msi]

CoV [%]

Max. Strain [Its]

CoV [%l

Poisson's Coefficient

CoV [%]

SLL

1/8"

109.9

11,272

5.2

9.75

3.9

12,437

18.4

0.155

17.0

SLL

1/4"

107.9

10,943

7.1

9.86

4.2

11,760

13.3

0.171

19.9

LLS

1/8"

90.9

8,724

8.7

10.42

4.3

9,103

11.0

0.613

11.2

LLS

114"

92.9

9,063

7.7

10.25

3.7

9,047

7.8

0.616

7.3

LLL

1/8"

88.3

9,536

6.9

9.26

3.4

9,754

12.0

0.152

18.8

LLL

1/4-

87.1

9,416

7.5

9.25

5.5

11,309

5.6

0.130

26.0

LSS

1/8"

52.3

10,608

5.5

4.93

4.3

12,165

4.6

0.709

12.6

LSS

1/4"

53.0

10,600

4.5

5.00

5.6

12,154

3.3

0.787

11.2

19

140t'_' 1204

_'100

" 80

60¢-

O

•_ 40r.

b- 20

SLL

..........

_!:!:!:!:!,...,.,...

................-.-.

.....,..........,,.,. ........_:_:_:_:_:

iii=_iii'=i_=

LLS LLL

D Baseline

[] Dogbone[] Net-Shape

LSS

Figure 5.4 Tensile Strength of Baseline, Dogbone and Net-Shape 2-D Braided Specimens.

5.2.3 Transverse Tension

A series of tests was also conducted along the material transverse direction using

specimens with a 2 inches wide by 7 inches long gage section. In this test, no fiber is

running along the test direction and all the load is carried by the bias yarns. Thus, this

test is very well suited to assess the strength penalty due to the crimp in these tows. As

shown in Figure 5.5 and Table 5.3, surprisingly low strength and strain were obtained.

Once again, the comparison of SLL and LLL shows that the increased tow size leads to a

strength and modulus reduction of 12% and 6% respectively.

40 .........................

35 F-

'- 30 ........ !_ ........ o_

25 ......... o_

lil= iiiiiiiiiil =o 20 ........ ! i o

'iiiiiiiii!!

ii °10 -i >

0 i_!_!!i_!ii!:I ..............II-

SLL LLS LLL LSS

Figure 5.5

LSS

Transverse Tension Strength and Nominal Strain for 2-D Braided Materials.

Table 5.3 Summary of Transverse Tension Properties of 2-D Braided Materials

Property SLL LLS LLL LSS l!

Strength [ksi] 35.2 15.2 30.9 24.7

Nominal Strain [#s] 4810 5840 4490 8440

CoV [%] 7.0 5.5 7.4 4.7

Modulus [msi] 7.32 2.60 6.87 2.92 I

ICoV [%] 5.8 6.0 1.7 1.5L : ' . : - u

2O

5.3 Stitched Uniweave M_terials

All stitched uniweave materials were tested using the baseline specimen and a test

section of 2 by 7 inches. Strength and stiffness properties are summarized in Table 5.4

and Figure 5.6 for all five materials. Overall, the scatter in the results was much less

than for the 2-D braids. The failure strains were also higher, indicating that the stitching

and weaving process introduces less of a strain concentration than the braiding process.

Material SU-1 with the smaller fiberglass stitches performed best, while material SU-5

with the large Kevlar stitches performed worst. Unfortunately, most failures occurred

near or under the fiberglass tabs due in part to the fact that these were fairly thick

specimens for which a load introduction through shear will introduce some stress

concentration in the outer plies.

Table 5.4 Summary of Longitudinal Tension Properties of Stitched Uniweave Materials

Property

Strength iksi]

Nominal Strain Ipsi

CoV [%]

Modulus [msi]

CoV !%1

SU-1

85.8

12,410

3.0

6.92

0.8

SU-2

75.9

11,700

2.1

6.49

1.5

SU-3

_.0

11,430

1.6

6.91

2.0

SU-4

82.2

11,630

2.8

7.06

0.3

SU-5

70.3

10,460

9.0

6.72

0.8

Poisson's Coefficient 0.306 0.293 0.341 0.303 0.304

100

90

80

,_ 70

_ 60_ 50

_- 400

'_ 30r--

_ 20

10

0

iiiiiiiiiiii............""""...........!.iiiiii'-!i !

_ itli!iiiiiiiii!iiiiiiiiii"iiiiiiiiiiiiiiiiiil""iiili!iiiiiiiiiiiiii"i_i!_i iiii _iiiiiiiiiiiiiiiiii- _iiiiiiiii!iiiiiiiiSU-1 SU-2 SU-3 SU-4 SU-5

¢..

C=

.o_r--

t--

¢.-

E0

z

14000

12000

10000

8000

6000

4000

2000

0

iii!iiiiiiiiii!iii.:.:.:,:.:.:,:.:.:

:!!!!!:!!!!!!!:_:!.:..::.:.:.:-:-:,:,..-......: ........,.,...,......

::!!!::!!!!!!!::i!::!!::::::::::::::::::

[!i!iiii!!i!_iii_!

i!!i!i!i!i!ii!!!i!

:-:.:-:-:-:.:-:-:................:.:-:-:-:.:-:-:-:

i!i::!::ili::i_i_!_;i:::::::::::::::::::

::::::::::::::::::::.:.:.:.:,:.:.u,:

SU-1

i!ililiiiiiiiiiii_ili_i_iiiii_i_iii_iiiiiiii_iiiii_i_i_

-i iiiiiii-iii::::::::: :::::::::............... .................. .................

:+:,:.:.:.:.:.:. :.:+:.:.:.:.:.:. .....:........ :.:.:.:.:.:.:.:.:.

............ .. :::::::::::::::::::.:.:.;.:.:.:.:.: :,:.:4+:.:.:+

:............ .........:::::::::::::::::::::::::::...................................-l_i_i_i_i_i_i_i_i_i" ,,;_i_,i_i_i_,i_i_i_,i-.........!iiiiiii_,iiiii'_iii_- ',ii',.iiiiiiiiiiiiii

I ......... I ':'!'!'!'!'!'!_!I ......... I .........SU-2 SU-3 SU-4 SU-5

Figure 5.6 Summary of Longitudinal Tension Strengths and Nominal Strains of

Stitched Uniweave Materials.

21


The 3-D woven materials were tested using the baseline specimen with a test section

of 2 by 7 inches. Strength and stiffness properties are summarized in Table 5.5 and

Figure 5.7 for all six materials. In two of three cases, the -2 material with the larger tow

size performed rather poorly. The Poisson's coefficient for this type of material is

always very low and for that reason, measurements exhibited a lot of scatter.

Table 5.5 Summary of Longitudinal Tension Properties of 3-D Woven Materials

Property

Strength [ksi]

Nominal Strain [psi

CoV [%l

OS-1

137.4

11,900

2.9

OS-2

92.9

7,890

2.6

TS-1

137.6

10,950

1.8

TS-2

131.8

11,350

1.5

LS-1

138.9

11,300

7.3

LS-2

96.1

7,870

5.1

Modulus [msiJ 11.55 11.78 12.57 11.61 12.29 12.22

CoV [%] 1.8 0.4 0.6 0.1 2.0 0.4

Poisson's Coefficient 0.034 0.046 0.060 0.040 0.060 0.040

CoV [%] 14.9 9.8 7.2 19.0 7.2 19.0

140

120

_10o

'_ 80e--

P60

N 40

.£_ 20

I--0

............. _ ...._--

, _

0S-1 0S-2 TS-1 IS-2

'i iiiiI

kS-1

!!!!!!!!!!!!i

:.:.:,:.x,:

i!!!i!!!!!!!_

ii!iiii_iiiiLS-2

12000

::!!i!i!!i_i!!!!i

,ooooi?Iiii.=_m_o 8000

o= lili"_ 6000 ........_!_i-:.:_Q) ::::::::

4000 iiiiiiiiiiii!ii"_ iiiii_iiiiiiill

....-.......-...

o 2000 !;!i!i!i!;!;!i!;...............,:.:,:.:.:.:.:.:2ZIZI

_.

OS-1

F iiiiiii iiiiiii!iiiiiiiii

-

i iiili,lliii-i , ii,0S-2 TS-1 TS-2 LS-1 LS-2

Figure 5.7 Comparison of Longitudinal Tension Strengths and Nominal Strains of

3-D Woven Materials.

5.5 Test Recommendations

The main concern in this test program was whether there are any scaling effects due

to the unit cell size compared to the specimen size. Based on the data shown here, very

little, if any, effects were observed from varying the specimen width and length.

Specimens as narrow as about 2 unit cells were tested with little difference from larger

one. Thus, for the materials evaluated here, the standard specimen width of 1.5 inch

22

would be considered adequate compared to unit cell sizes of 0.4 inch to 0.5 inch.

Another concern in unnotched tension tests is to obtain a good failure mode inside

the test section and away from the tab region. Most laminated materials tend to fail

close to the tabs where small stress concentrations cannot be avoided. However, for the

2-D braided materials, failure was obtained within the test section, mostly due to the

fact that the material itself contains stress concentrations due to tow waviness and

crimp more severe than at the edge of the tabs so as to induce failure in the gage section.

The use of a dogbone specimen produced strength results which are not significantly

different from the straight sided specimen. Therefore, the use of a dogbone specimen is

probably not worth the extra cost of specimen machining. Conversely, for the stitched

uniweave material, since the material appears to contain less severe stress

concentrations, failure usually occurred in the tab regions. The use of thinner specimens

is recommended for this type of material.

Scatter in the results for the 2-D braided materials was slightly higher than for other

materials and Poisson's coefficient measurements were particularly poor. This suggests

the use of a somewhat larger number of specimens in order to obtain statistically

adequate test data and to avoid taking a penalty when calculating B-basis allowables.

23

6. Open-Hole Tension Test Program

The strength of textile composites with open holes under unidirectional tensile

loading is examined in this chapter. The effect of specimen width and hole diameter is

the main focus of the test method evaluation.

6.1 Test Confiouration

A straight-sided coupon with no tabs was used in this test program, as shown in

Figure 6.1. The length was kept constant and the width varied as indicated below in the

test matrix. All holes were drilled with ST carbide drill bits. Specimens were gripped in

hydraulic grips and loaded to failure at a rate of 0.05 in/min. No strain measurements

were taken and only load and machine stroke were recorded during these tests.

Figure 6.1

_ +.003"

CL F D..000-

l : .............. W/2 + 0 005"

I

[-_ 11,5"

Open Hole Specimen Configuration.

The test matrix used for the Open Hole Tension test program is shown in Table 6.1.

Because the objective is the evaluation of the test method, the first parameter of interest

is the specimen width to hole diameter ratio. A ratio of W/D equal to 6 is typically used

in testing composite materials. However, since material availability can be sometimes

limited, it is of interest to find out how small a specimen can be used while still

obtaining adequate data. Conversely, as in the tension test program, one needs to verify

whether the large unit cell size has any influence and whether larger specimens than

usual need to be used. Two material systems, SLL and LLS, were tested more

extensively to investigate this effect on both thin and thick specimens. A second effect,

more important from a mechanics of material point of view is the hole diameter since it

is well known that strength is strongly dependent on the notch size for composite

materials. Fewer tests were conducted on the other two 2-D braid architectures, LLL

and LSS. Only 1.50 inch wide specimens were tested in this case. For all other material

systems, i.e., stitched uniweave and 3-D woven angle interlock, 1.50 inch wide

specimens were also used.

24

Table 6.1 Test Matrix for Open Hole Tension Test Program

Dimensions

Width Diameter W/D SLL SLL LLS

[in] iinl 1/8" 1/4" 1/8"

1.50 .375 4 3 3 3

1.50 .250 6 3 3 3

1.50 .188 8 3 3 3

2.25 .562 4 3 3 3

2.25 .375 6 3 3 3

2.25 .281 8 3 3 3

3.00 .750 4 3 3 3

3.00 .500 6 3 3 3

3.00 .375 8 3 3 3

27 27 27

Material Systems

LLS LLL LLL LSS LSS Others

1/4" 1/8" 1/4" 1/8" 1/4" (1)

3 3

3 3

3 3

3 3 3 3 3

3 3 3 3 3

3 3 3 3 3

3

3

3

27 9 9 9 9 99


6.2 2-D Braid Materiai#

6.2.1 Width to Diameter Ratio Effect

When analyzing data from an open hole test, there are several ways to calculate and

report stress at failure. As described in Section 3.4, the options are gross stress, net stress

and stress corrected to infinite plate width. As an example, these three stresses are

shown in Figure 6.2 for two braid architectures, SLL and LLS. This data was obtained

for 1/8" specimens with a 3/8" hole using three test configurations with w/d=4, 6 and

8. If there is no material or specimen sensitivity to w/d and if the finite width correction

factor is accurate, the corrected stress should be the same for all test configurations. The

data shown in Figure 6.2 indicates that this is roughly the case and that the corrected

stress remains constant within the data scatter. On the other hand, net stress clearly

varies with w/d and is not the best way to report the data. Since the values obtained are

always higher, it is also a less conservative approach when using the data for design

purpose. Therefore, stress calculated with the infinite width plate correction factor will

be used in this report for all open hole tests. Other stresses can always be calculated if

necessary from the raw data presented in Appendix A. Further more, this method is

customarily used when determining composite material allowables. Also, several series

of specimens were tested with both a varying hole diameter and w/d. Without a way of

correcting the effect of w/d, it would not be possible to determine the influence of the

hole diameter.

25

_120_

c-o 60

oae-

_ 40

-6 20:"r

¢- 0

O 4

Figure 6.2

2-D Braid, SLL Architecture

-"'°"--Gross INet

Corrected

I I I

.--_.120"

.E

1ooi-_ _ 80!

r--O_ 60(/)

_ 40:o--c 20e-

I "_ 08 0


•-_o---Gros s

---o-.--Ne t-----a,-_ Corrected

5 6 7 4 5 6 7Width to Diameter Ratio Width to Diameter Ratio

13

Comparison of Gross, Net and Corrected Stress in SLL and LLS 1/8"

Thick Specimens with a 3/8" Diameter Hole.

6.2.2 Thickness Effect

Testing was conducted with two different thicknesses for all architectures, but data

is available at a common hole diameter only for the SLL and LLS with a 3/8" hole

diameter. This data, shown in Figure 6.3, reveals a certain sensitivity to thickness when

a specimen with a low w/d is used. For instance, at w/d=4, the mean strength of the

1/4" specimens is 17% below that of the 1/8" ones. At w/d=8, the difference is reduced

to 5%. For the LLS architecture, the difference is 16% at w/d=4, and 8% at w/d=8.

_ 2-D Braid, SLL Architecture '_

_--_100"T !1 _'90

90 1 m

•80 • B i __" 8070 o o o _ 70

o ¢n 6060 o =•- o 50

" 50 1 m ,/o in,oK c

_ 40I-- 40 ....,, .,.,_:_,. I--(D"6 30 _ 30 --r- 20 o 1/4"Thick T° 20-¢.-

_. lo g 10-O 0 = = = _0

2 4 6 8 2

Width to Diameter Ratio

Figure 6.3


ii

I

0

1/8" Thick

1/4" Thick

I I

4 6

Width to Diameter Ratio

I

8

Comparison of Open Hole Tensile Strength in SLL and LLS 1/8" and 1/4"

Thick Specimens with a 3/8" Diameter Hole.

I_,2.3 Hole Size Effect

The parameter with the strongest influence is the hole diameter and it is well known

that the strength of notched composite materials is sensitive to the notch size itself.

Results for the four braid architectures are shown in Figure 6.4.a to 6.4.d. Because of the

26

thickness sensitivity mentioned in the previous section, data from 1/8" and 1/4"

specimens were separated. Unnotched strength (i.e., d = 0) is also indicated in each plot

for reference.

The curve fitting technique described in Section 3.4 was used to help interpret the

data and establish a relationship between strength and hole diameter. Note that

unnotched strength is not used in this fitting process. Because of the scatter in data and

the variability from panel to panel, this technique is very helpful in identifying series of

data points for a given material which differ from the overall trend in behavior.

However, it is also possible that fitting the whole range of hole diameters with a single

curve is not completely accurate. For instance, at small hole diameters, i.e., hole sizes

less than the unit cell width, one could expect a slightly different behavior and notch

sensitivity than in specimens with a hole much larger than a unit cell. The results for the

SLL architecture are fairly typical of the data obtained. For instance, for the 1/8"

specimens, note that two points fall below the trend, for d=0.28" and d=0.56". Similarly,

for the 1/8" LLS architecture, the data for d--0.25" and d=0.50" do not follow the

general trend.

In general, the data for the thick specimens is always lower than for the thin

specimens and appears to be slightly more consistent for the various hole diameters.

However, the low values are partially due to the fact that the data was obtained in

several cases from specimen with a low w/d. Also, there appears to be more difference

between the two thicknesses at small diameters than at large diameters.

Figure 6.4.a

100

U3

80¢-

(3)C

60CO

c.9m 40C

I---

20

..............

[] 1/8" Specimens

S=72 17*d^-O. 165

0 1/4" Specimens

- S=7250"d^-0.129

0 .... t .... ! .... I .... I

0.00 0.20 0.40 0.60 0.80

Hole Diameter [in]

Effect of Hole Diameter on Tension Strength of SLL Specimens.

27

00 ........... _ .......... .-.. ............ . ........

_ 80 ........... "_ ........... "ID.................

6o ...................... .2_":.._.-. - .._..___'_'_'___O9

¢-o

"P= 4O

2O

0

0.00

Q 1/8" Specimens

S=61.27"d^-0.208

Q 114" Specimens

-S=54.19"d^-0254

.... I .... I .... I .... I

0.20 0.40 0.60 0.80

Hole Diameter [in]

Figure 6.4.b Effect of Hole Diameter on Tension Strength of LLS Specimens.

20 ............. _ ....... - ..................... ---

_-,001 .....

0t)

¢-

.940r-

I--

2O

0

0.00

E:! 1/8" Specimens

,--.. .................. ..o

S=5299"d^-0315

• 1/4" Specimens

S=53.51°d^-0.244

.... I .... I,,.,,I .... I .... I .... I

0.10 0.20 0.30 0.40 0.50 0.60

Hole Diameter [in]

Figure 6.4.c Effect of Hole Diameter on Tension Strength of LLL Specimens.

28

0.00 0.10 0.20 0.30 0.40 0.50 0.60

Hole Diameter [in]

Figure 6.4.d Effect of Hole Diameter on Tension Strength of LSS Specimens.

6.2.4 Summary

Mean stresses corrected to infinite plate width and coefficients of variation are

shown for each configuration in Table 6.2. Most coefficients of variation are below 7%.

Once again, the comparison of SLL and LLL allows to assess the strength penalty due to

the use of larger tow sizes.

Table 6.2 Mean Stress and CoV for Open Hole Tension Tests of 2-D Braided Materials

Hole Diameter

[in]

0.188

W/D=8

Property

Strength Iksi]

Coy I%1

0.250 Strength [ksi]

W/D =6 CoV I%1


W/D = 8 CoY 1%]


W/D = 4,6, 8(1) CoV [%]


W/D = 6 CoV [%]


W/D = 4 CoY [%1

0.750

W/D =4

Strength [ksi]

Coy [%1

SLL SLL LLS LLS LLL LLL LSS LSS

1/8- 1/4- 1/8- 1/4- 1/8- 1/4- 1/8- 1/4-

99.1 91.8 89.5 86.2

3.5 9.o 4.6 2.1

91.4 82.2 74.3 75.6

6.7 18.5 6.6 2.2

82.4 91.7 81.5 72.7 77.5 72.7 40.3 40.8

3.5 1.5 0.9 3.0 9.2 3.0 7.9 3.7

87.6 76.9 76.3 68.4 74.8 68.4 37.3 40.1

5.4 11.4 6.4 4.9 2.5 4.9 5.9 5.0

81.0 81.9 78.0 65.8

6.7 4.4 4.8 4.2

75.5 77.0 66.7 61.6 62.8 61.6 33.6 34.7

4.0 4.5 3.9 5.0 4.8 5.0 6.7 4.6

79.2 76.2 62.9 59.7

2.3 8.0 3.8 5.2

(1) Average Result for W/D = 4, 6 and 8

29

6.3 _titched Uniweave Materials

A more limited series of open-hole tension tests was conducted with stitched

uniweave materials and mean stresses corrected to infinite plate width are shown in

Figure 6.5 and Table 6.3. The results for all five materials were quite similar, indicating

that the type of stitching used appears to have little influence on the strength. Therefore,

a single curve appears to be sufficient to fit all the data. Once again, very little scatter in

the data was observed for this type of material.

100.0 .............................................

Figure 6.5

0.0 'lllll'llllllZllllllllllllllllllllllllllll'l_

60,0 ..........................................

u)SU-2

SU-3

SU-4

SU-5

S_35.30"d ^-0 30':3

40.0 O

A

O20.O

O

l | m I

t-.(2_rY)t-OI--

0.0 ' i ,' , , , I .... I d , , , I

0.00 0.10 0.20 0.30 0.40

Hole Diameter [in]

Effect of Hole Diameter on Open Hole Tension

Uniweave Materials.

Strength of Stitched-

Table 6.3 Mean Strength and CoV for Open Hole Tests of Stitched-Uniweave Materials

Hole Diameter iin]

0.188

W/D=4

Property

Strength [ksi]

CoY 1%1


W/D=6 CoVl%}

0.375

W/D = 8

Strength [ksi]

CoY 1%]

SU-1 SU-2

59.2 58.0

0.9 1.8

54.1 52.4

2.8 0.8

47.8 47.0

5.1 0.9

SU-3

58.0

4.6

53.0

7.1

48.5

3.0

SU-4 SU-5

61.3 56.6

0.9 2.8

55.9 51.4

2.0 2.7

52.6 46.8

3.1 4.2

30

6.4 3-D Woven Materi_l$

A limited series of open-hole tension tests was conducted with 3-D woven materials

and results are shown in Figure 6.6 and Table 6.4. The lack of a clear trend and the

limited data made it difficult to use the log-log fitting technique here for three of the

materials, OS-2, LS-2 and LS-1. Based on the best fit curves obtained for the other three

materials, an exponent of -0.25 was chosen for these three materials and the value of the

constant was chosen to fit two of the three data points. The results of this operation are

shown in Figure 6.7.a to 6.7.c. Since the exponents are approximately the same in all the

curve fits, a comparison of the constants can be used to compare the notch sensitivity of

the different configurations. This comparison indicates that the -2 configurations (with

the smaller tow sizes) suffer a strength penalty of 21% for OS, 15% for LS and 15% for

TS. Among the -1 configurations, LS-1 is the strongest by about 15% compared to TS-1.

140.0 =............................................

0120.0 ................... .._ ..... "0" ................

0

_" 100.0 ........................... "6 ............ "1_'"

r-- rl 0S-1 IP'_ 80.0 ............ -m---C " ............... --AL

II OS-2 j"

c 60.0 --- OLS-1 ..................................o

c • LS-2® 40.0 ......................................

I.-OTS-1

20.0 .... OTS-2 ..................................

0.0 .... I .... I .... I .... I

0.00 0.10 0.20 0.30 0.40

Figure 6.6

Hole Diameter [in]

Open Hole Tension Strength Data for 3-D Woven Materials.

Table 6.4 Mean Strength and CoV for Open Hole Tests of 3-D Woven Materials

Hole Diameter [in]

0.188

W/D =4

Property

Strength [ksi]

CoY 1%1


W/D = 6 CoY I%1

0.375

W/D=8

Strength [ksi]

CoY i%1

OS-1 OS-2 LS-1 LS-2 TS-1 TS-2

117.5 80.0 126.5 80.9 109.3 92.6

0.9 12.1 0.3 17.1 2.7 5.0

101.2 87.9 119.2 99.3 100.4 87.9

12.8 1.6 6.8 0.8 3.5 4.8

97.7 72.9 87.1 90,3 92.2 78.2

12.2 17.8 5.1 5.0 0.3 3.6

31

140

120

-_,100

¢-

c 80

C/),- 60.o= 40(D

20

0

[] 0S-1

s = 74.7"d^_ 254

0 0S-2

........ s = 58.9"d^-0.25

[]

O _''" q=

.... I .... I .... ! .... I

0 0.1 0.2 0.3 0.4

Hole Diameter [in]

Figure 6.7.a Effect of Hole Diameter on Open Hole Tension Strength of 3-D Woven

Materials OS-1 and OS-2.

140

120

-=- 100e-

_- 80

09¢ 60._o¢/)

_- 40a)

F--

20

[] LS-1

s = 83.2"d^-0.25

O LS-2

........ s = 70.8"d^-0.25

o

0 .... I .... I .... I .... I

0 0.1 0.2 0.3 0.4

Hole Diameter [in]

Figure 6.7.b Effect of Hole Diameter on Open Hole Tension Strength of 3-D Woven

Materials LS-1 and LS-2.

32

140

Figure 6.7.c

120

100.E:

,'- 80

CO_- 60o

,'- 40I.-

20

0

[] TS-1 I

s = 72.4"dA-0248

O TS-2

........ s = 61.6"dA-0.248

i w i w I i i w

0 0.1

I .... I .... I

0.2 0.3 0.4

Hole Diameter [in]

Effect of Hole Diameter on Open Hole Tension Strength of 3-D Woven

Materials TS-1 and TS-2.


The standard straight-sided untabbed specimen configuration performed well in all

the testing done here. The two parameters that were seen to influence the test are the

specimen thickness and width to diameter ratio (W/D). For all 2-D braided materials,

thicker specimens exhibited a lower strength, but this is not necessarily a consequence

of the test method. When using the correction factor for infinite plate width, little effect

of W/D was observed for the thin (1/8") specimens. For the thick specimens (1/4"), a

lower strength was obtained for W/D=4. Therefore, a ratio of W/D=6 is recommended

as a minimum. Also, the use of multiple hole sizes and the log-log fit of strength versus

diameter was particularly useful in detecting anomalies.

33

7. In-Plane Compression Test Program

The strength of textile composites under unidirectional compressive loading is

examined in this chapter. In contrast to tension testing, a large number of test fixtures

and specimen configurations are available for compression testing. Thus, the main focus

of this investigation is a comparison of the different methods.

7.1 Test Confiourations

Seven different techniques, described below, were evaluated in this investigation

using the test matrix shown in Table 7.1. Sketches of the different configurations are

shown in Figures 7.1.a to 7.1.c.

Sandwich column compression specimens were tested in the Zabora Sandwich

Compression fixture. The specimen ends are machined with a shallow 10 ° "V" in order

to match the specimen ends to the fixture.

The NASA short block fixture is the smallest specimen of all used. The loaded edges

are clamped over 0.3" and no side support is provided. Load is introduced by contact

across the specimen cross-section and thus specimen machining and alignment in the

fixture is extremely important. Because the specimen is very short, a slower loading rate

of 0.025" per minute is recommended.

The modified IITRI is a straight specimen with unbevelled fiberglass tabs. Instead of

using the special IITRI loading fixture, the specimen is gripped in the test machine with

hydraulic grips. Special attention to machining the specimen tabs is taken to insure that

the tab surfaces are parallel. Care is also taken in aligning the specimen so that no initial

bending is induced in the specimen.

The Boeing Compression After Impact (CAI) fixture utilizes a rectangular 4" by 6"

specimen. The loaded edges are clamped in the fixture over 0.3", while the sides are

simply supported between rails which are snug but not tight so that the specimen can

slide between them. Load is introduced by contact against the specimen ends, and thus,

parallelism of the ends is important. The standard loading rate of 0.05" per minute is

used.

The NASA ST-4 specimen is very similar to the Boeing CAI specimen and is

described in the NASA 1092 ST-4 specification (Ref. 5). The only difference is that a

larger 5" by 10" specimen is used.

The Boeing Open Hole Compression and Zabora fixtures were used also to test

unnotched specimens. The specimen is a straight untabbed 1.5" by 12" coupon.

34

Table 7.1 Test Matrix for Compression Test Program.

Dimensions Material Systems

Width Length Note SLL SLL LLS LLS LLL LLL LSS LSS[in] [in] 1/8" 1/4" 1/8" 1/4" 1/8" 1/4" 1/8" 1/4"

Sandwich (2olurnn

3.00 6.00 3 3 3 3

1.50 6.00 3 3

2.25 6.00 3 3

3.00 2.00 3 3

3.00 8.00 3 3

3.00 6.00 Core Effect 3 3

NASA Short Block

1.50 1.50 3 3 3 3

1.50 1.00 3 3

1.50 2.00 3 3

NASA ST-4

5.00 10.0 3 3 3 3

Boeing CAI

4.00 6.00 3 3 3 3

Modified I|TR1

1.50 1.00 3 3 3 3 3 3

1.50 1.50 3 3 3 3

1.50 2.00 3 3

1.50 1.50 Transverse 3 3 3 3

Boeing OHC

1.50 12.00

1.50 12.00 Net-Shape 3 3 3 3

Zabora Fixture

1.50 I 11.50 [ 3 3 3 3

27 27 27 27 12 15 12 15

Others(1)

3

3

3

99


Figure 7.1.a

Le th

O"

Modified IITRI Specimen and NASA Short Block Specimen.

35

l"Z

Nomex Honeycomb Core

Composite Facesheet

1/16" Fiberglass Tabs

Aluminum Honeycomb Core

1.52"

7.s.,o I i:o

I I I

I I I

O i i iO

.07"

3.0"

e'-

.E

J

12."

Figure 7.1.b Sandwich Column Specimen, Zabora Fixture and Boeing OHC Fixture.

5" NASA ST-4,r

4" Boeing CAI

_N__ Clarr

I:

I

(i

I'

,/ .Simply

)ed

-- Clamp_

• /d

10" NAS, ST-4,

6" Boeil g CAI 12"

ppo_ed

I t

Figure 7.1.c NASA ST-4 or Boeing CAI Specimen and Boeing OHC or Zabora Fixture

Specimen.

36


7.2.1 Test Section Length and Thickness Effects

The main concern in compression testing is whether the test fixture provides

adequate support to prevent failure by global specimen instability. Thus, specimen gage

length and thickness are of prime interest. On the other hand, just as in tensile testing, a

certain minimum number of unit cells should be present across the test section to insure

a representative failure mode. This effect was investigated with the SLL and LLS braid

for the NASA Short Block and modified IITRI methods. The baseline test section used

here is 1/4 inch thick, 1.5 inches wide and 1.5 inches long. Specimens were also tested

with a length of I and 2 inches to detect any sensitivity to length, and with a thickness

of 1/8 inch to detect sensitivity to thickness.

Results for the two braid types are shown in Figure 7.2 and 7.3, where strength is

reported. In general, there does not appear to be a very strong trend for the range of

values tested, although the 2 inch gage length seemed to lead to more scatter and

slightly lower values. Note that one set of data, the 1 inch long LLS NASA Short Block

test, is much above the other results and appears to be an anomaly for which no cause

could be identified. Moduli measured with these configurations are shown in Figure 7.4

where no effect from gage length can be observed.

Also, at a gage length of 1 inch, little difference was found between 1/8" and 1/4"

thick specimen. For instance, for the SLL specimens the strength of the 1/8" is 4% below

that of the 1/4" specimen when both are tested with the modified IITRI method.

However, when examining strain data obtained using back-to-back gages, the 1/8"

specimen does exhibit some non-linearity in behavior which indicates some stability

problem.

100

80t-

c-

.¢ 60u)

cL 40Eo 200

o

.0

Figure 7.2


°

I I

1.5 2.0

Test Section Length [in]

100

80t-

t-

_ 60if)

d. 40Eo

0


El

20

0 I I

1.0 1.5 2.0

Test Section Length [in]

Test Section Length Effect on Compression Strength in NASA Short Block

Test Configuration.

37

100Or)

80r"

60

d. 40Eo 20

0

1.0

Figure 7.3

10

8¢,D

"5 6"OO

4d.E 2O

0

.0

Figure 7.4


[] [][]

[]

I (

1.5 2.0

100

80J_

_" 60

o9

0

o

40

20

0

1.(


B

! I

1.5 2.0

Test Section Length [in] Test Section Length [in]

Test Section Length Effect on Compression Strength in modified IITRI Test

Configuration.


[] IITRI

• NASA SB

' l10

E 8

5 6O

d.EOo

2-D Braid, LLS Architecture[]

| i

[] IITRI I• NASA SB

4

2

0

1.0

I I I

1.5 2.0 1.5 2.0

Gage Length [in] Gage Length [in]

Test Section Length Effect on Compression Modulus in NASA Short Block

and modified IITRI Test Configurations.

7.2.2 Longitudinal Compression

The compression stiffness modulus and ultimate strength were determined for all

four braids using the NASA Short Block, modified IITRI, NASA ST-4, Boeing CAI and

Zabora test methods. The moduli are reported in Figure 7.5. The NASA Short Block test

method always resulted in lower moduli, while the Zabora fixture usually produced

slightly higher values.

The strength and nominal strain (defined as the stress divided by nominal modulus)

of all five test methods are summarized in Figure 7.6.a to 7.6.b for all four materials. The

NASA Short Block and Zabora test methods gave the highest results each in two of the

four cases. The modified IITRI and Boeing CAI test method consistently gave lower

results than the NASA Short Block by I0 to 15%. Results from the NASA ST-4 were

always much below the others, indicating that this method is not suitable for this type

of testing. This is in part due to the large test section, which does not provide adequate

stability to test unnotched or unflawed specimens to failure. A summary of the

38

compression properties is provided in Table 7.2. The strength value from the NASA

Short Block, modified IITRI and Zabora fixture tests are reported, while the moduli are

the averages of the NASA Short Block, modified IITRI and Zabora tests. In terms of

scatter, the Short Block test method produced the lowest coefficients of variation. One

possible explanation for the higher strength of the Short Block specimen than the

modified IITRI specimen is the difference in load introduction and the fact that both

these specimens are fairly thick: in the Short Block test, load is introduced by contact

over the whole specimen cross-section, resulting in a uniform loading through-the-

thickness, while in the modified IITRI specimen, load is introduced in shear in the outer

plies of the specimen, thus resulting in slightly higher stress levels in these plies nearthe tabs.

10.00

"_ 8.00

"o 6.00O

t-"

.£ 4.00

Q.E 2.ooo

O

0.00

10.00

'_ 8.00

"D 6.00o

e-

.£ 4.OO

E 2.00o

O

0.00

Figure 7.5

.:.:.:.:.:.:.:

iiiililililili:::::::

i!i!i!i!i!iii!

............,.i:_:_:[:_:_:7:m

..,........,.._!!!i!i!i_i!i;i1!1!1!1!17!1!m:;:;:;:::::::;

:::::::

:.:.:.:.:.:.:,

....... i

NASA$8

ii!iiiTiiiiiiii,..............:i:i:i:i:i:i:i:i!:!:!:!:!:!:!:!:

iiTiliiiiTili

!!!!!!!!!!!!_!!!

iiii!ii!!!ii_iii,.,.............

................

.:.:.:.:.:.:.:,:,...........,.,,

1771111iiiiiii:.:.:.:.:.:.:o

iiiiiiiiiiiiii!iiiIITRI

SLL

.........iiiiiiiiiiiTi!i_ iii!ii_,i',iiiii',i':-

iiiiii!iiiiiiii::iiiiiiiiiiiiTi

NASASTy4

".','.'.'.'. D

--i_ii!iiii_ii!i::::::::::::::

_..,iii!iii;iiiiiiiiiiiiiii!ii!i --

iTiiiii!iii!i_iiiiiii!7_!:

iiii]ii!iiiiiii-

iiiiiiiii!iill

Boeing Zab_aCAI

10.00

E a00

"o 6.00o

e--

.£ 4.OO

I,O

E 2,0oo

O

0.00

LLS_ _:.:,:.:.:.:.:.:.:

.:.:.:.:.:.:.:,:- . ,,....,..,.,..,,. m i__i_ !i!i!!i......... :_:_:_:_:_:[:i:_:_

iiiii!_iiii_ii_i i iiiiiiii!i!i!i!i!il .............................................iiiiiiii!ii771!iiiiiiiiiiiii!iiii !:i:i:i:i:i:i:i:i: :iiii!i!i!!i!iiiiii:::::5::::::::: :::::::::::::::::: :::::::::::::::::::::::::::::::::: :!:i:i:!:i:i:i:!:i :::::::::i:i:i:i:i:i:i:i: ...........................iiiiiiTi.........!ili!iiiiiiiiiii .........

ili!iUiiiiiiiii!...................:.:.:.:.:.:.:+:

:i:i:i:i:!:i:i:i i!i!ili!i!i!!!i!!!.,,,.,..,..,,.,...iiiiiiiiiiiiiiii - !iiiiiiiiii!iiiiii _ !:i:!:!:i:!:i:!:i:

i!iii!iiiiiiiiii: ;ii i ili iiii; i i i;i iT;iiiii!i!iiiiiiiiiiiiii!iiiii!iii!iii......... 7!!!i!i!i!i!iii!!....... I I

NASA IITRI$8

!iTiiii!iiiiiii-iiiiiiiiiiTii!i..................

.: :+:.:.:.:.: i!!_iiiiiiii!iii

ii:;::_:d;i_::i 71i17i7]!=:ii:-

:i:i:i:i:_:i:i:! iiiiiiiii!iiiiii

.................. _i]_::!iiii:=i:;i_-!!i!iiiiiiiiiill!=:i!Z:711i.......,..., ........

=i!iiiii_i=:i_i::iii!iiiiiiiil;ili

iiiiii!ii!jii!iiiiiiiiiiiiiiiiiiiii.............................

7iiiiii!Ti!ii7,!iiiT!i!i-. .......-::::::::: i!iiiiiiii!!711

::::::::::::::::::::::::_!_i_:;:,_:;::_i_I ................I 'I

NASA Boeing ZaboraST-4 CAI

LLL

:i:i:i:i:!:_:i:im !iiiiiiiiiiiiiiiiil

........ ,..,...,..,..,.,,............ .........

.-.-.-.-.-.-.- i:i:i:!:!:!:!:i: ........ :

:2::::::::::: m :':':':':':':':" ,,..,..,..,,.,..

i_i_i_i_i_i_i_iiiii}iiTii!iiiiii::i:,i:7:iii:i::i::::::: ii_!iiiiii!!ii!i ::::::::::::::::::

.............................i!!iTiiiiiiT!i

............... :,:,:,:.:+:.:,.:i:i:i:i:i:i: !;!:i:!;!:!:i:i: i:i:i:i:i:i:i:i:i:

:':':':':':':': i!_!_!_!_]_ :!:i:i:i:i:i:i:i:i

:i;!:i:!:!:!:! :::::::: . ........

iiiiiiiiiiiiii :!:!:!:!:]:!:!:!: :_:[:]:_:_:_:_:_:........ ,....,,,.,.,,..,........... ...........

......... ........, ..,....... :,:.:,:.:.:.:.: .................

...............iii::iiiilitiI ::!iiii::!::_ii::f:::i 7'iii::i:::iiiiiiiiNASA IITRI NASA

$8 ST-4

Compression

500

_iiiiiiiii!ili!!i m

i_i_i_i_i_i_iiilliiiiiiiiii!ii!i

- i!iiTiiiiTi!,17i!Tiiiii!i

j ....................

!iiiiiTili_i_ii!iiiiii!!!i_i_

:,:.:.:.:.:.:.:. ;:::::::::::::

_!!!iii!i!i!i!i__ ::;:::::;:::;:

]ii ,!ilUi!iiiiii- i

Boeing ZaboraCAI

E

"o 3.00o

r-

.o 2.00

E _.00o

O

0.00

..........

i!iiiiiT ......!!i!i!iL!!!!!!!!]!i_._..... :!;i:!:!:i:i

ilililiTi :i:i:i:i:i:i

;.:.:.:.:-:1 ::::',:::::::_

NASA IITRI$8

Modulus of 2-D Braided Materials.

LSS

:.:,:,:.:+:.:.,........

ii!_i]ii!!iiii.,,.,,.,..,..,

_i!7]!!_771!:,:.:.:.:.:.:.

i!i!!!i!Tiiiiii_iiiii_iii!i:.:,:,:.:.:.:.

iiii77iiiiiliiiiiiiiTi!ii::::::::::::::

iii_?i_iliiii

:;:::::::::::::,:.:.:.:.:.:.

i!i!i!i!i!i!_!__!i!i!i!i!i!i!i

NASAST-4

..........-..._

t

.........,....,........ .:.:...:..:_

:::::::::::::::i ::;:;:;:::::::1

. ....-.... _

:::::::::::::::t :i:i:i:i:i;i:il

-.-.-.- -.-.-

i:Gi:i:i

::iiiii_!ii_TilI-' .....,,'I I

Boeing ZaboraCAI

39

90.0

80.0

'---' 70.0

60.0

50.0c 40.0.9

30.0

E 20.0o

¢O 10.0

1O0O0

.@moo

2o,D

E_" 6000t-

O3r- 4000O

03

2o0o

_l:!:_!:!$k",i

NASA IITRI NASA Boeing Zabora$8 ST-4 CAI

.=Ul.:;:;:;:::;:;:;:;:!m

_..,-.-...-.-...-._

o.o O o =E_;!iiiiiii_iINASA IITRI NASA Boeing Zabora

SB ST4 CAI

Figure 7.6.a Compression Strength and Nominal Strain of SLL Braid

90.0

,---, 80.0

70.0¢--

60.0

*-- 50.0O3

t- 40.0._o

30.0

t,_E 2O.0o

O 10.0

0.0

:::.::!

i;ili;i;ili;ili!i;:::::Y::: _ _!!!!!!!!!!!i!i!!i]ii!............-...,

......... il!iii:.:.:.:.:.:.:.:.:.

NASA IITRI NASA Boeing ZaboraSB ST-4 CAI

1OOOO

"E"

80002o

6000¢-.

O34000

O

2oooQ.Eo

O0

11::;:;::'2.::;:;::11

=.:.:.:.:.:.:.:.:.:_ ..........

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::i :-:-::-:-:::-::........... --.i:_!::!!!_!!_::-- .-.=:_:_:_:..._:_:_-

_=-:..'.:::::::.,.'.::.]

' ...................I ' ...................INASA IITRI NASA Boeing Zabom

SB ST-4 CAI

Figure 7.6.b Compression Strength and Nominal Strain of LLS Braid

90.0

80.0

70.01-

60.0

•,-- 50.0O3

e- 40.0.o_ 30.0

E m.0oO 10.0

0.0

I.........._......

NASA IITRI NASA Boeing zal0oraSB ST-,4 CAI

1OO0O

.@eooo

2o

i;6000

t-

.t-,

034000

o

U_

_0ooQ_Eo

O0

NASA IITRI NASA Boeing$8 ST-4 CAI

Figure 7.6.c Compression Strength and Nominal Strain of LLL Braid

_ora

40

,50.0

45.0

4o.0

:_ 35.0

_lO

25.0

g•_ 200

15,0Q.E _o.oo

5.0

0.0!

Figure 7.6.d

ii:i:!:¢!iii!iii ,:i:i:i:i:_:i:i:ii:

.'.'.'.'.'.'." l:i:i:_:i:i:_:i:i:i

_i!iiiiiii!iii!i--!i_!_i_iiiii!i_!_i:x:.:x.x

_.::+x+x.:

i:i:i:i:i:i:i:i:

?)i}?ii)?)i)?)iii_iiiii!i_ii:ii................iiiiiii_:iiiiiiiiIi! .........

::::::::;:;::::: ;:::::::;::::5:::

_iii!iii!iii!i___!_ii!_i!!!iiiiiii_.:,:.:,:,:.:.:,: .........

ii!!!i!!i!iiiiii-- iiiii!iiiiii!iiiii':::::::::::: i:!;!:;:i:i:i:i:i:

........ -- iiii:!:!ii:iiiii:_

........ i :!:!:_:i:!:]:!:i:ii

NASA IITRI$8

12OO0

10000

--I ::iii::iiiiiiiii!--. .................::!i!_ii:!ii_ii: o

- iiiiiiiiiiiiiiiii..................-iiiii!i;iiiiii;i;- __:=!iliiii;ii=.!;!ii2!i!iii!iiiiiii2--_ _-

:_i::i_i::_i_i::i_i_iiiiiiiiiiiiii!!!.................i!i!iiiiiiiiii!!i,_ _-l:iii!_.!!:_i!_:i:ii!_:iii!!:iiiiiii::::i_i_i::_

::::::::::::::::: :?:i:i:?:i:i:i:[:i ::::::.:::::::::::| O 4000

:::::::::::::i;:: : :.: :.:.:.:: : ::::::::::::::::21

!_i!iii_:i_::_il-!!i!!:/iiii!iii_:-........- _- _000i:i:i:!:!:_:i:i:!: __ E

,_i!iiil;iii:_!!i!_!!ii_i;ii;-iiiiiiii!i!iiiiioo............... i'ii _ .......... I 0! !

NASA Boeing ZaboraST-4 CAI

i:ilili_!i!_!i_

'[[::. _ !!iii!_iiiiiiiiiii•,.....,.,,...., .:.:.:.:,:,:.:.:.:

- -iiiiiii_ii!iii!iiiii-

........ :::..::. .........._i_:i_i_!ii!ii_ :!:!:!:!:i:i:i:!:i !iii!_ili!i!!i!iii

•:,:.:+:.:+: ::::::::::::::;:::_::!_iiiiiiiii::iiii::iii!i:::iij:_:i,i,i:!:i:

:_:::::_-ililili_ili_i_i_i!........._:!:!:!:i:i:!:i: ',','..'.'.'.,,"

::_:::::i, !iiiiiiiii!iii_i!!i !_!_i_!_i_i::i_INASA IITRI NASA

SB ST-4

Compression Strength and Nominal Strain of LSS Braid

iiii!!iiiiiiiiii_

......... _!!!!_!!

:::::::::::::::::: ...............+x+>x+: +x+:x.:

......... +x+x+:

..................!i!i_i_!!!i!!!!!

iiiiiiiiiiiiiiii!i:.:.:.:.:.:.:.:iiiiiiii!i!i!i!i......................... .:.:.:.:.:.:.:.:

: | _i!i!_!i:i_i_:!IBoeing Zabora

CAI

Table 7.2 Summary of Longitudinal Compression Properties for 2-D Braid Materials

Property

NASA SB Strength lksil

CoY I%1

Nominal Strain [ITS/

Mod. IITRi Strength Iksil

CoV [%1

Nominal Strain [I.tsl

Zabora Strength [ksil

CoY [%1

Nomina] Strain [/as]

SLL

78.8

3.7

9140

70.6

6.4

7860

84.4

14.2

9328

LLS

62.8

2.7

7211

59.2

5.3

6743

58.0

4.2

6405

LLL

58.6

7.7

6995

48.7

10.8

5699

66.6

5.4

7467

LSS

46.2

1.7

11391

45.5

5.9

1O378

44.9

3.9

9511

Modulus [msil 8.92 8.82 8.37 4.38

CoV [%1 2.9 5.4 8.5 7.3

7.2.3 Sandwich Column

The results of the sandwich column specimens were not included in the previous

discussion since they were not satisfactory for two reasons. The first problem with the

sandwich specimens is that no fiber volume fraction measurements were obtained on

the facesheet materials because the specimens were delivered as a complete sandwich.

Thus a normalized thickness corresponding to a 60% fiber volume fraction could not be

established as for the other tests. Instead, a nominal 0.0625" thickness was used for all

specimens. The second problem is that no material strength data could be generated

with this specimen configuration. The failure mode of this specimen is always a

structural failure mode rather than a material failure mode. In all tests, failure occurred

41

when one of the facesheets separated from the core due to either core or bond failure.

Results from these tests are summarized in Table 7.3. Moduli measured with this

method were usually lower than when measured with the other test methods, possibly

due to the use of nominal thickness. In one case (LLS), the modulus was much higher

and in another (LLL) much lower, with no available explanation for this.

Table 7.3 Sandwich Column Compression Properties for 2-D Braid Materials.

Property

Strength [ksi]

Coy I%1

Nominal Strain [las]

Modulus [msi]

CoY I%1

SLL

28.2

8.3

365O

7.74

3.8

LLS

_.3

6.1

3020

11.34

2.5

LLL

16.3

6.5

2990

5.46

3.2

LSS

16.7

1.2

4870

3.43

1.2

7.2.4 Boeing Open Hole Compression Fixture

The results of the Boeing Open Hole Compression fixture were also not included in

the previous discussion since they were not satisfactory. Abnormally high strength

results were obtained in several cases probably due to friction or interference between

the fixture and specimen.

7.2.5 Transverse Compression

Specimens of each material were tested in the transverse direction with the modified

IITRI method. This is particularly interesting for this type of material since there are no

fibers running directly along the loading direction and all the load is carried by the

braided tows. As seen in Table 7.4, the transverse strength of the SLL, LLS and LLL

architecture is relatively poor. The change in tow size between the SLL and LLL has a

particularly drastic effect and leads to a 25% strength reduction, but practically no

change in modulus.

Table 7.4 Summary of Transverse Compression Properties for 2-D Braid Materials UsingModified IITRI Test Method

Property

Strength [ksil

CoV [% ]

Nominal Strain [Its]

SLL

42.1

3.4

5805

LLS

25.3

10.1

8377

LLL

31.6

4.8

4252

LSS

43.1

2.1

14224

Modulus ]msi] 7.25 3.03 7.42 3.03

CoY [%! 2.2 1.8 1.3 4.7

42

7.3 Stitched Uniweaves Material_

7.3.1 Longitudinal Compression

The testing of the stitched uniweave material was conducted with the NASA Short

Block and modified IITRI specimens only. Results are shown in Table 7.5. The

conclusions from these tests are very similar to the ones found in the previous section.

The Short Block test gave higher strength values by 9 to 14 %, but a slightly lower

modulus by 4 to 8 % compared to the modified IITRI. The best strength was achieved by

the SU-lmaterial with the 3K S2-Glass stitch. For the Kevlar stitches, increasing the

stitch spacing or yarn size actually gave slightly higher results, but in general, the

influence of the stitching type is small. Also, as for other properties, the coefficients of

variation for this type of material were less than for the 2-D braid.

Table 75 Summary of Trartwerse Compression Prow_rties for Stitched Uniweave Materials

Property

Mod. IITRI Strength [ksi]

Coy I%1

Nominal Strain [Its]

NASA SB Strength [ksi]

CoY I%1

Nominal Strain I_s]

SU-1

52.3

1.0

8235

57.0

3.3

9783

SU-2

44.9

1.8

7414

51.1

3.3

8759

SU-3

45.5

3.5

7477

52.0

2.5

8875

SU-4

49.7

0.8

7470

54.9

1.8

8559

SU-5

46.8

0.7

7519

53.8

5.1

9061

Mod. IITRI Modulus [msi] 6.35 6.06 6.09 6.65 6.22

CoY [% ] 0.9 0.8 1.3 0.4 0.5

NASA SB Modulus [msi] 5.83 5.84 5.86 6.41 5.93

CoV [% ] 2.6 0.9 0.8 0.2 0.8


Compression testing was also conducted in the transverse direction using the

modified IITRI method. As shown in Table 7.6, although the layup is quasi-isotropic,

the strength results are surprisingly higher than in the longitudinal direction, ranging

from 4.5% for the SU-1 to 21.8% for the SU-5 (when comparing the modified IITRI

method in both cases). Modulus showed much less difference between the two

directions, except for SU-5 (9.4% difference). One possible explanation is that the

stitching runs parallel to the 0 ° direction and induced more fiber distortion in the 0 ° ply

than in the 90 ° ply.

43

Table 7.6 Summary of Transverse Compression Properties for Stitched Uniweave

Materials Using the Modified IITRI Test Method

Property

Strength [ksil

CoY [%i

Nominal Strain [its]

Modulus Imsil

CoY l%1

SU-1

54.7

3.9

8623

6.34

2.6

SU-2

51.1

1.8

8343

6.12

.9

SU-3

52.1

3.3

8336

6.25

0.8

SU-4

53.5

3.7

7881

6.79

(1.2

SU-5

57.0

1.6

8365

6.81

0.8


7.4. 1 Longitudinal Compression

Testing of the 3-D woven materials leads to the same conclusion as before, with the

Short Block Method yielding the highest strength in all but one case as shown in Table

7.7. Unlike in the previous case, the difference in moduli between the two test method

was smaller. In terms of tow size influence (the difference between the -1 and -2

material), the smaller tow size (-1) usually produced a slightly higher strength and

modulus. The orthogonal interlock (OS architecture) produced better strength results,

possibly because of the lesser distortion induced in the 0 ° fibers. Coefficients of

variations were in general low.

Table 7.7 Summary of Longitudinal Compression Pro :_erties for 3-D Woven Materials.

Property

Mod. IITRI Strength [ksil

CoY 1%1

Nominal Strain [itsl

OS-1

84.0

5.0

7661

OS-2

77.8

7.3

7615

TS-1

76.2

5.0

6990

TS-2

63.8

3.4

6167

LS-I

76.7

3.4

6713

LS-2

62.2

2.4

5649

NASA SB Strength [ksi] 87.0 90.6 75.4 70.2 81.7 79.9

CoV [%] 3.3 6.0 1.5 6.0 4.8 8.4

Nominal Strain [its] 7895 8714 7198 6952 7282 7315

Mod. I1TRI Modulus 10.96 10.21 10.9 10.35 11.43 11.01

[msi] 0.9 1.1 1.2 1.0 1.0 0.6

CoY [%1

NASA SB Modulus [msi] 11.03 10.40 10.48 10.09 11.23 10.92

CoV [%] 1.6 6.5 2.9 2.6 1.3 1.5


As for the previous materials, testing was also conducted in the transverse direction

with the modified IITRI method. Assuming that the nominal strains at failure are equal

for loading in the longitudinal and transverse directions, the strengths and moduli for

44

the transverse direction should be about 60% of those in the longitudinal direction

based on the 0 ° and 90 ° fiber percentages. As seen in Table 7.8, except for the LS-1 and

LS-2 weaves, the nominal strains at failure were similar and those for the weaves with

the largest yarns (-1) were somewhat less than those with the smallest yarns(-2). The

nominal strains at failure for the LS-1 and LS-2 weaves were significantly less than the

others, and that for LS-1 somewhat greater than for LS-2. The transverse strength

deviated from 60% of the longitudinal strengths accordingly. The median value for the

transverse moduli was 57%.

Table 7.8 Summary of Longitudinal Compression Properties for 3-D Woven Materials

the Using Modified IITRI Test

Property

Strength [ksi]

CoV [%1

Nominal Strain [Ds]

Modulus [msi]

CoV I%]

O.%1

41.3

2.3

6729

6.14

2.7

OS-2

52.2

1.4

8875

5.88

1.0

TS-1

37.2

7.1

6410

5.80

0.8

TS-2

52.7

3.8

7197

7.32

2.3

L.%2

32.4

14.4

5264

6.15

1.4

LS-2

27.8

20.2

4371

6.35

0.2

7.5 Test RecommendatiQn_

An A or B basis allowable increases with increasing mean value and decreases with

increasing coefficient of variation (CoV). Thus, the test method that would produce the

maximum allowable would maximize the mean and minimize the CoV. Test data for

the different materials were pooled, and means and CoVs were calculated for the NASA

short block, modified IITRI and Zabora methods. The CoVs for the various materials

can be pooled together directly since they are non-dimensional quantities, but the

means cannot. Thus, a normalized metric for the mean was calculated as follows:

1) Means for each material were calculated with:

1 N_

Xm N _ xmnn=1

where m is the material number, n the test method number, N the number of test

methods and Xmnthe mean value for a given test method and material combination.

2) A mean deviation from _mWaS calculated for each test method with:

I _. Xrnn - Xm_-Xn = M -- Xrnm=l

where M is the number of materials for a given test method.

Values of Axn and CoV for the strengths and moduli are given in Table 7.9 and plotted

in Figures 7.7 to 7.10.

45

The results indicate that the modified IITRI test method gave the largest allowable

for compression moduli, but the NASA Short Block and Zabora methods gave the

largest allowable for strength. Note however that the number of data points for this

method was much smaller. Also, because of the side supports on the specimen, there is

a possibility of some load being lost through friction in the fixture. In terms of mean

strength, the NASA Short Block test method gave consistently higher results than the

modified IITRI method by about 9% to 12 %.

In terms of stability, a length to thickness ratio (L/t) of less than 10 is recommended

for the modified IITRI and NASA Short Block method. A ratio of 6 appears to be a good

compromise in terms of having a sufficiently large test section and good stability. Both

the NASA ST-4 and Boeing CAI specimens are inadequate for compression testing of

unnotched specimens because of their lack of stability.

Table 7.9 Mean Deviations AXn and CoVs for Unnotched Compression Test Methods

Test Method

Material Property Modified I1TRI NASA Short Block Zabora

A---xn CoY A---xn CoV A---xn CoY

2-D Modulus 2.1% 6.4 % -7.7 % 4.0 % 5.6 % 3.3 %

Braids Strength -6.7 % 8.5 % 2.1% 3.9 % 4.6 % 6.9 %

Stitched Modulus 2.5 % 0.9 % -2.5 % 2.1% n/a n/a

Uniweave Strength -5.9 % 1.5 % 5.9 % 3.2 % n/a n/a

3-D Modulus 0.2 % 1.5 % -0.2 % 2.8 % n/a n/a

Woven Strength -4.9 % 4.4 % 4.9 % 5.0 % n/a n/a

Figure 7.7

6.0

,_, 4.0

¢" 2.0

E 0.0_or" -2.0.9

"_ -4,0a_o

-6.0

-8.0

I!_i!i!i!i!i!i!i!i!iiiiiiiiiiiiiiiiiiiii

!iiiill:.:.:.:.:-:.:.:.:.:

i!iiiiiiiiiiiiiiiii!!!!!!!!!!!!!::!!!!_!

IITR_ NASA SB Zabora

[] 2-D Braid

[] Stitched Uniweaw

[] 3-D Woven

Deviation from Mean Strength for Unnotched Compression Test Methods.

46

Figure 7.8

Figure 7.9

Figure 7.10

9.0

8.0 4-,

7.0_

o_ 6.0 -.-,

>o 5.00

c 4.0

3.0

2.0

1.0

0.0

,...........

:.:.:.:.:+:.:.

............. .......,..•.

.............

!iii!iii!,........Ji:i:i:i:

-- I I:i:!:i:!.:.:.:.:,'k,,r,,

i!ililiiiii!i!iill

!!!!!!!!iiii!iii!!

iiiiiiiiiiiiiiii!'.:.:<.:.:+:.:

.:.:+:.:.:+:

................

!!!!!!!!!!_!!!i!:.:.:.:+:+:.

!:!:!:!:!:!:_:i:...............•.....•..._..,.

..............................

NASA SBI ITRI Zabora

I_ 2-D Braid

Stitched Uniweave

3-D Woven

Mean Strength CoVs for Unnotched Compression Test Methods.6.0

4.0

c 2.0

E 0.0oc -2.0 -

._o

"._ -4.0 --

t_-6.0 --

-8.0 --

Deviation

Methods.

i!!!i!i!i!i!i!!!

IITRI

from

l!i!iiiiiiiiiiiiiiiii_iJF::::.-.-.......:

,ll

ilili,iiii, ID!!!ii!_!!i!ii!ii!!!ii!i;iii [] Stitched Uniweave

i!i'::!i!i!i!i!i':i! m3-DWoven1:1:1:1:1:1:191:• • : : :

NASA SB Zabora

Mean Modulus for Unnotched Compression

7.0

6.0

5.0

> 4.0OOt-in 3.0

2.0

1.0

0.0

iiiiii_

!i!!

:::;::

iill

_!!! - 1

i!iiiiiiiii!iiiiiiii!iil

_i!i!i!i!i!i!i!iii!_!

:+:+:.:.:.:.:.:.

::::::::::::::::::::::::::::::

iii!iiiiiiiiiiii!i!:

I :::::::::::::::::::::

IITRI NASA SB Zabora

l i 2-D Braid

Stitched Uniweave

3-D Woven

Mean Modulus CoVs for Unnotched Compression Test Methods.

Test

47

8. Open Hole Compression Test Program

The strength of textile composites with open holes under unidirectional compression

loading is examined in this chapter. The test methods and the effect of hole diameter are

the main focus of this test program.

8.1 Test Confiaurations

Six of the seven test methods discussed in Chapter 7 were used as shown in Table

Table 8.1 Test Matrix for Open Hole Compression Test Program.

Dimensions [in]

Width Diameter W/D

Boein[_ IOpen Hole Comp.

1.50 .375 4

1..50 .250 6

1.50 .188 8

NASA Short Block

1.50 .375 4

1.50 .250 6

1.50 .188 8

NASA 1142

1.50 .375 4

1.50 .250 6

1.50 .188 8

Modified IITRI

1.50 .375 4

1.50 .250 6

1.50 .188 8

Zabora Fixture

1.50 .375 4

1.50 .250 6

1.50 .188 8

Boein[_ CAI Fixture

4.00 0.500 4

4.O0 0.8OO 5

4.00 1.000 8

NASA ST-4

5.00 I 1.250 I 4

Material Systems

SLL SLL LLS LLS LLL LLL LSS LSS Others

1/8" 1/4" 1/8" 1/4" 1/8" 1/4" 1/8" 1/4" (1)

3 3

3 3

3 3

3 3 3

3 3

3 3 3

3 3

3 3

3 3 3

3 3

3

3 3 3 3

3 3 3 3

3 3 3 3

3 3 3 3

3 3 3 3

3 3 3 3

3 3

3 3 3

3 3

12

3 3

18 39 18 39 12 18

3

18 132

(1) Five Stitched Uniweave and Six 3-D Woven Materials

48

8.1. The sandwich column was dropped becauseof its complexity to manufacture andits poor performance in the previous testprogram. In addition to these, the NASA 1142method, shown in Figure 8.1, was also considered (Ref. 6). Because both the holediameter and the width to diameter ratio are varied simultaneously, the correctionfactor for infinite width was used again to calculate the strength and make it possible tostudy the influence of hole diameter. However, no direct comparison of the influence ofW/D canbe made. No strain gageswere used on thesespecimens.

10"

iiiiiiiiiiiiiiiiiiiiiiiiii C,amped Clampe d iiiiii;iiiiiiiii!i!;i;!i!

.............lug. \iiiii::iii::?:?:i::ili!i::ii?:i::ii::i_iiiiii_7......

1.5o" _!i !!V iiiiiiiiii!iiiii!iiiiii i!i

Figure 8.1 NASA 1142 Specimen Configuration.


8.2.1 Test Method Comparison

Five of the seven test methods were compared directly: the Boeing Open Hole

Compression (OHC) fixture, the NASA Short Block specimen, the NASA 1142

specimen, the modified IITRI specimen and the Zabora Test Fixture. Two of the 2-D

braided materials, the SLL architecture and the LLS architecture were used for this

comparison. Some sets of data seem to show a high scatter, while others do not. Possible

explanations are variability in material quality or a material sensitivity to hole position

with respect to architecture due to the non-uniform nature of the material.

Mean values and CoVs for all test methods are shown in Figures 8.2 and 8.3,

respectively, and Table 8.2. As in previous sections, the column marked "Strain" is the

nominal strain obtained by dividing ultimate stress by the average compression

modulus measured in the previous section.

No single method produced the highest strengths for all materials. On the other

hand, the Boeing OHC and Zabora test methods typically produced the highest CoVs.

The thinnest materials (1/8") were tested with these two methods; perhaps local

instabilities caused the large CoVs. The CoVs for the LSS material were the lowest, even

for the 1/8" thick material. This is possibly due to the fact that this is a rather soft layup

which is not as notch sensitive as the other two.

49

7O

--'=" 6O(/)

40o_t-

.o_ 30_0

2oEoo 10

Figure

6O

_ 50

4O-

30-t-O

¢O

_ 20-

Eo 10-

O

0

Figure

r-

¢-

¢-

.o

Eo

O

Figure


lili i_ii

0. 188" Hole

8.2.a Comparison

Methods of

0.250" Hole

of Open Hole Compression

SLL Materials.


] :i

_iill

0.375" Hole

Strength for

iili_l_i ?iiiii!iii!iiiiiiii_

0.1 88" Hole

8.2.b Comparison

Methods

60

50

40

30

20

10-

00.188"

iiii_iiIti iiiiiiiiiiii]i

lliiili!iiiiiiiiiiiiiiiiillI

0.250" Hole 0.375" Hole

of Open Hole Compression

of LLS Materials.

2-D Braid, LLL Architecture:::.:::.:.::::::./: : ::_!i!ii_:ili!i!:

:.:,x,:,x.:,

:iiiii_ii_ii!ii_! :::::::::::::::_

......H.,., .::+::.:+:!

iiiiiii!ili!!!!! i !i_ii!i!_:_:!-_

:.:,;:,:,::,. .:.:.::+::.l:i:!:i:i:_:i:i:i i:_:i:i:i:i:_:_|

i:i:_:i:i:i:i:i: .:,:,:.:.:.:.:+ : .....,...,_:J:i:i:i:J:;:J:_ 2::::2:-

!i_i_iii_i_i!i:i_ _:_;i_i!'_--.........,,......... .........=i?iiiii!i!:!i!i!::..... r_:?_i:i:i_ii_!!.......:+:+:.:.:. :.:.:.:,::.:.:,a

........ iiiiiiiiii!iiii|::: ::.:: ::::: .........::::.:::::::::: ::::::::::::::::!

::.:+:x: I I :.:.x.:.+:,..

Hole 0.250" Hole

Compression8.2.c Comparison of Open Hole

Methods of LLL Materials.

Strength for

: i_

I

0.375" Hole

Strength for

• Boeing OHC

• NASA SB

[] NASA 1142

[] Mod. IITRI

[] Zabora

Various Test

• Boeing OHC

• NASA SB

E3 NASA 1142

[] Mod IITRI

[] Zabora

Various Test

• Boeing OHC

• NASA SB

[] NASA 1142

r_ Mod. IITRI

[] Zabora

Various Test

5O

t-

t-

O3

¢-O

Or)

Q..Eo

¢,.)

Figure

40.

35.

30.

25

20

15

10

5

0

_HHH

HH_H

H.H

.... H'

2-D Braid, LSS Architecture

I

H

_-HHHH

Xq:::+.::

H •

::X:::

IO. 188" Hole 0.250" Hole 0.375" Hole

8.2.dComparison of Open Hole Compression Strength

Methods of LSS Materials.

• Boeing OH(

• NASA SB

t_ NASA 114_

D Mod. IITRI

1:3Zabora

I

for Various Test

25

,'- 20o

"C

m 15>

o

o 50

Figure 8.3.a


-1J

O. 188" Hole O.250" Hole

II

I0.375" Hole

• Boeing OHC

II NASA SB

I_ NASA 1142

[] Mod IITRI

[3 Zabora

Comparison of Coefficient of Variations for Open Hole Compression Test

Methods of SLL Materials.

Figure 8.3.b


• Boeing OHC

[] NASA SB

E_ NASA 1142

1:3M0d. IITRI

O Zabora

,0.188" Hole 0.250" Hole 0.375" Hole


Methods of LLS Materials.

51

35

3O

25

_' 20._o

"t- 15>

o

10

o 5-

0

Figure 8.3.c

0.188" Hole


u

• Boeing OHC

J NASA SB

El NASA 1142

rl Mod IITRI

13 Zabora

0.250" Hole 0.375" Hole


Methods of LLL Materials.

,.- 4o.D

.¢,-

3>

"6

o 1L)

Figure 8.3.d

2-D Braid, LSS Architecture

O. 188" Hole 0.250" Hole

• Boeing OHC

B NASA SB

E] NASA 1142

13Mod IITRI

FI Zabora

0.375" Hole


Methods of LSS Materials.

52

Table 8.2 Summary of Open Hole Compression Test Results for 2-D Braided Materials

SLL

D Stress Strain CoV

[inl lksil I%1

Boeing Open Hole Compression

0.188 56.0 6281 25.9

0.250 59.1 6630 23.9

0.375 54.8 6139 6.4

NASA Short Block

0.188 68.5 7684 3.3

0.250 58.7 6585 11.9

0.375 50.9 5707 3.5

NASA 1142 Fixture

0.188 62.7 7034 3.9

0.250 55.8 6252 14.2

0.375 54.6 6116 0.9

Modified IITRI Specimen

0.188 64.(I 7172 3.7

0.250 64.6 7247 15.5

0.375 48.1 5392 0.8

Zabora Fixture

0.188 64.2 7201 5.4

0.250 63.6 7135 7.9

0.375 56.9 6379 6.6

Boeing CAI Fixture

0.500 54.5 6107 12.7

0.800 41.6 4667 3.6

1.000 41.6 4667 4.1

NASA ST-4 Fixture

1.250 I 36.8 I 4122 I 14.6

LLS

Stress Strain CoV

[ksil [%1

47.4 538(/ 5.8

46.4 5259

43.4 4924 4.6

50.0 5669 2.3

47.0 5333 6.3

41.1 4661 5.9

48.9 5542 3.9

49.5 5610 3.6

45.2 5121 7.1

LLL LSS

Stress Strain CoV Stress Strain CoV

[ksil [%1 [ksil [%1

39.1 4669 26.2

j .............

34.4 I 7848 3.3

....

43.1 5155 2.(1 32.8 7489 2.9

51.8 6185 11.0 36.8 8405 3.0

52.6 5958 1.2 58.7 7018 3.5

49.4 5601 6.4 53.9 6438 5.7

45.3 5138 8.7 51.1 6102 5.9

54.7 62(/2 5.1 47.5 5677 26.(I

47.5 5380 9.8 44.4 5310 17.9

44.7 5(}66 2.2 42.5 5079 32.3

40.7 4617 3.1

35.9 4073 5.7

32.3 3658 4.3

37.0 8447 2.0

36.6 8352 1.9

33.8 7734 (1.5

38.7 4623 2.0 31.4 7164 0.6

1306I 65I 60I I I I 18.2.2 Hole Size Effect

In addition to the test methods compared in the previous section, the NASA ST-4

and Boeing CAI specimens were used to examine the open hole compression strength in

the presence of larger holes than the ones used in the other specimens. As for the open

hole tension tests, the log-log fitting technique of strength versus hole diameter was

used to analyze the results. For each hole diameter, the results from different test

methods were averaged together when available. Some series of results with a high CoV

53

or a low mean due to a premature failure in one of the specimen, were eliminated in

certain cases from this average whenever it was possible to reduce the overall scatter for

a given diameter. Results for all four 2-D braids are shown in Figure 8.4 and a rather

good fit is obtained in all cases. For reference purpose, the mean compression strength

is also indicated in each plot. For the hole diameters of 0.188", 0.250" and 0.375", the

specimens were only 1.50" wide; thus, for the 0.375" diameter hole, the ligaments on

either side of the hole are only 0.563" wide. The unit cell widths, which ranged from

0.415" to 0.829" for the braids were essentially as wide or wider than the ligaments. On

the other hand, the CAI and ST-4 specimen have a good amount of material in the net

section. When looking at the data point corresponding to the 0.375" hole in Figure 8.4,

one can see that it lies within the normal scatter of the curve fit across all hole sizes.

Thus, this would indicate that the small number of material unit cells in the net section

did not significantly influence the results.

Once again, an interesting observation of the tow size effect can be made by

comparing SLL and LLL. For a hole diameters of 0.188", SLL is about 26% stronger than

LLL. However, for a larger hole diameter.of 0.800", the difference is only 7%. This is

possibly due to the fact that for large hole diameters, materials appear to be more

homogenous compared to the hole size and thus, the coarse architecture of LLL makes

less of a difference. The effect of changing the braid angle from 70 ° to 45 ° is seen in

comparing the results of LLL and LLS. Interestingly, in term of stress, there is not much

difference between the two. Finally, the LSS material with its high percentage of 45 °

appears to have little sensitivity to the notch size.

7O

40

{/3

Or) 30 ................................................

Eo 20 [] SLL Tesl lil .........................

O

10 s = 40.5"d^- 304

0 ,, , I,,, I,,,I, ,,I,, ,I,,,I ,,,I

0.00 0.20 0.40 0.60 0.80 1.00 120 1.40

Hole Diameter [in]

Figure 8.4.a Effect of Hole Diameter on Open Hole Compression Strength of 2-D

Braided Materials SLL.

54

0 ......................................... -------

-_ 6o ................................................

5O

40g"_ 30

E 20o

10

0

0.00

[] LLS Test ..........................

S = 330"d^-278

,, ,I,,, I,,,I, ,,I,, ,I,,,I ,,,I

0.20 0.40 0.60 0.80 1.00 1.20 1.40

Hole Diameter [in]

Figure 8.4.b Effect of Hole Diameter on Open Hole Compression Strength of 2-D

Braided Materials LLS.

0 ................................................

0 ................................................

60 ...............................................

5O

o

30

O..

E 2OoO

10 i1 [] LLL TestS -- 365"d^-.187

0

0.00

,, ,I,,, I,,,I, ,,I,, ,I,,,I ,,,I

0.20 0.40 0.60 0.80 1.00 1.20 1.40

Hole Diameter [in]

Figure 8.4.c Effect of Hole Diameter on Open Hole Compression Strength of 2-D

Braided Material LLL.

55

5O

t-O

r_Eo0

3O

2O

I0

L

D LSS Test

S = 30.5*dA-.106 ..........................

0 ,, ,I,,, I,,,I, ,,I,, , I,,,I ,,,I

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40

Hole Diameter [in]

Figure 8.4.d Effect of Hole Diameter on Open Hole Compression Strength of 2-D

Braided Material LSS.

8.3 Stitched Uniweave Materials

Stitched uniweave materials were tested only with the Boeing OHC specimen and

modified IITRI methods. Results from this testing are summarized in Table 8.3. A

comparison of the two methods for the 1/4" hole shows that the average difference is

only 2.1% , with, unlike for the 2-D braided materials, the modified IITRI being the

lower. A comparison of the mean CoV for each method is shown in Figure 8.5 and

reveals that both method are fairly similar. Note that in general, the scatter is much

lower than for the 2-D braids.

A comparison of the five materials is shown in Figure 8.6, where nominal strains are

calculated with the compression modulus; not much difference is observed between the

different types of stitching: SU-1 fared best, with SU-3 12% lower. Using the same log-

log fit of strength versus hole diameter as in the open-hole tension test program, a

comparison of SU-1 and SU-3 is shown in Figure 8.7, where SU-3 appears to be

somewhat more notch sensitive than SU-1.

56

Table83 Summary of Opm Hole Corn

Boeing OHC

0.250" Hole

SU-1

Strength [ksi]

CoY l%l

47.3

4.2

_ression Test Results for Stitched _ve Materiak

SU -3

40.1

4.1

SU4

40.6

1.8

SU-2

42.1

1.8

SU-5

45.8

1.2

Mod. IITRI Strength 47.9 42.4 45.0 46.3 46.8

0.188" Hole CoV 2.2 2.1 1.0 3.4 0.8


0.250" Hole CoV 3.4 7.2 4.7 2.1 3.5


0.375" Hole CoV 3.3 3.5 1.2 0.9 1.2

Figure 8.5

>O

oC

:s

4.50

4.00 I

3.50 ",-

3.00 .*-

2.50 JF { ;:I.:.I.I:;.I:I:;:;:::;:I:I:I:I:i oo, i!...........!....1.5o..,- I ......................

" iC::_:;i_::_:;_::;::_i_:::::!i;!_::_1.00 -.- i_iiii;_iiiii_;_iiiii_::i::!iiii::i::iiiii::i

o.5of II ! ,i!iii' il0.00 , iii_iiiii:,iii;_!i;_;_i':': ii;ii_il

Boeing OHC0.250"

!i!ii!i!iiiiJiiiiiiiiiii [_iiiiiiiiiiiii!iiiiiii::!:!:!:!:!:!:!:!:!S_

i:i:i:i:i:i:i:i:i:i:i:

:?iiiiiii!?i?!i_?!_!i .:.:.:,:.:.:.:.:,:.:

iiiiiiiiiiiiiiiiiiii ....................... ':i:::,::!::i::iii?iii?iiiiiii!i?ii::

!!!iii!!!iiiiiiiiiii is::s::iii:=:iiis:=siiiiii!ii::i::iiii...................._!!!!!!!!_!!!:!!!!! :::::::::::::::::::::::::::::::::iiiiiii!}i::::::::::::::::::::::::::::::::

.......... •..................... :.i!i!i:.;il.............................. ,. ,.,., ..,.....,....,....

j m::: :::: j _ii!_iiiiiiiiiii!ii!i! j i:!:_:i:i: i:i'!:!:!:!:!:i:?i: I

Mod. IITRI Mod. IITRI Mod. IITRI

0.188" 0.250" 0.375"

Comparison of Mean Coefficient of Variation for all Stitched Uniweave

Open Hole Compression Tests.

(,0

r"

C

.o_¢/;

8_EO

o

O

"1-

c

8.O

50.0

40.0

30.0

20.0

10.0

0.0

..................:!:_;!:!:!:!:!:!:!:!.........................,.....................:...

i!ili!i!iiiiiiiiiiii..,....,...............,.....,..........,..,..,:,..,....., ,...,...,...,,,.,...............,.,,..,....,........,...., ....,......:::::5:::::::::::::

i:ii:i:ii:i;;:i:iil;ii;iiiiiil;iiill::::::::::::::::::::.,..............:.:.:.:.:.:.:.:.:.:._ii!iiiiiiii!i!iii_i

iiii!iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii!i!i!i!i!i!i!i!i!ij!;!;!::::::;:::::i:::

SU-1

Figure 8.6

_Z?: Z'!??I

...,.:...,..,,,,,.,......, ..,....:....................._.,.......

..........,....

...............................!iii!i!i!i!i_i!i!!!i

!i!i!i!i!iiiiiiiiiii•........,,........:+:.:.::.:.:.:.:.::::::::::::::::::::.,.............

::::::::::.........................,._.,..::::::::::::::::::::

:::::::::::::::::::::::::::::::::::::+:.:.:.:.:.:.:.:.

iiiiiiiiiiiii!iiiiii

SU-2

iiiiiiii!iiiiiiiiiii;::;::::::::::::::::

iiiiii!iiiiiii!iiii!_iiiCiCiCili_i_:::::::::::::::::;::i!!i!i_!!_i!iii!i!_i,.,.,,.,,,,,. ,..

!iiiiiiiiiiiiiiii!ill

!i!i!i!i!i!i!i!!iii_i)il))i)il;);i))i)il:.:.:.:.:.:,:.:,:+:

,........ ,...,.::2:::::::::::::::..,.,,...........

i!ii_iiiiiiiiii_iiill

:iiiCiiiCi_i_iii_I "

SU-3

iiiiiiiiiiiii_ii_iii!i I

iffjiiiiii i,:.:+:.:.:.:.:.:..

!iiii!iii!!ii!ii!!!_iiili!iiiiiiiiiiiiiiiii_: :i:!::::i:i:::!::i

iii!iiiiiiiiiii!iiiii!

:.::.;.:.: ;.:; : :.

;::::::::::

ii::i:.!:_i::;:.!ii::iiiiiii!:!:i:!:!:i:i:i:!:]:?.:i:i:i:i:i:i:iSi:i:!::i:i:i:!:i:i:: :!:!::.:.:.:.:+:.:.:.:,::+:.:.:.:.:,:,:.:,:,................,:.:.:.:.;,:.:.::,:.:..,.., ,..,.,,.,::::::::::::::::::::::

! ISU-4

Comparison of 1/4"

iii_ii%!iii!:i:!:!:i:i:!:!:!:!:!

iiiiiiii!!ii!iiii!!ii!iiii[ii_i_iiiiiiii

iiii!ii!ii!ii!i!!iil!iiiii!iii!i!ii!ii!!. .... -.......

.:,:.:+:.:.:.:,:.:., _................,. ,..

::::::::::::::::::::::+:.:.:,:.;.:.:.:,::::::::::::5::::::....,.,. ,.....:!:_:!¢!:!;i:i:i:i:.:+:.:,:,:,:,:,:.:i:i:iSi:i:_:i:i:i:

i!!ii!i_ii_!!!!:i!!!..........

SU-5

Open

8000c

7000

._ 6000

5000

E4000

3000

2000

1000

o

Hole Compression

::::::::::::::::::::::::::::::::::::::::::::

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::,.,, .,., ....., :::::::::::::::::::iiiii::iii=:iiiii::iiii21::::::::::::::::::::!:!:!:_:!:i:_q:!:_:[ ii!iiiii_i!i[iiiiiii

iiii::iiiii::iiiii::ii_il:i_iC::ii_is::_i:i:!:,:,:.:+:.:.:.:.:+ :.:.:.:.:.:.::.:.:

ii::!::!ii::!ii::i::iiil;ilj!_:i:::!_!::!_:::_:!!_!_!ii_i_T!!_i_i_ ..........

iiiiiiiiiiiiiii i i .............iiiiiiiiii!iii' iiiii""'""-'"'""" :::::2::::::::':::

iiiiiiiiii

!!ii!iiiiiiiiiii;ii!ii!iiiiiiiiiiiiiii!i!

','.',V.'.V..'.'.

i1-1 '1-,i .... _

SU-1 SU-2

Strength

":':T:':':':':'f:

:E:_:_:i:i:i:!:i:!:i......,.....,...,......,•....,...

iiiiiiiiiiiiii iiiii......,..........

iiiiii!!iiiiiiiiiiii ili i!!i! !!iiiiii...y,..,..,,.....

!iii!ii!i!i!i!i!iii

:.:,:,:,:.:+:.:.:

j .

SU-3

Strains for Stitched Uniweave Materials.

iiiiiiii!iiiiiiiiiii ::::::::::::::::::::

::::::::::::::::::::

. ,..,..,...,, ... ..........T!!!iii!!ii!!i!!!i!i!i I ii_iiii!_i_i_i_i_i_:

iiii!iii ,ili ,ii i;iii........... !i!:!i!i',ili!ii iil::::::::::::::::::::: ..,.. ,.........

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::i:i:i:i:i:i:i:i:i:i:i: , : :':':':':':':':':'........... ,.......,......,

;!_!iiiiiiiiil;iiiiii!....................ii!:::i!iii!ii==!::!::iii!:_:::::_:_:_:_:_:_:_

::iii==ili!i!iii:=i!i!i!iI=_:_:_:::_:_:_:_:_:_.....................iil;ii!iii::C::i!_ii::i.:i:i:i:i:i:i:i:_:i:i

I I ISU-4 SU-5

and Nominal

57

0 "mml_mlmmllmlmmlmmlmmmmNmmlmmmmmmmmmmmmmllmlmmml

Figure 8.7

0 ......................... _ ..... _ ...............

'3

r-.ou}

EOo

30

20

10

0

!_ su-t

S = 36.3 • d_-.168

0 su-3

s = 290 *d_-257

; ,' , , I , , , , ! = ,'

0.00 0.10 0.20

, , I .... I .... I

0.30 0.40 0.50

Hole Diameter [in]

Effect of Hole Diameter on Open Hole Compression Strength of Stitched

Uniweave Materials.


The results of the open hole compression testing of the 3-D woven materials are

summarized in Table 8.4. The average difference between Boeing OHC and modified

IITRI is only about 2.4% and the average CoV is about 6%. A comparison of the six

materials is shown in Figure 8.8. The OS-1 configuration yielded the highest strength,

while OS-2 produced the lowest. Other configurations exhibited fairly similar strengths.

Table 8.4 Summary of Open Hole Compression Test Results for 3-D Woven Materials

Boeing OHC

0.250" Hole

Strength [ksi]

CoV 1%1

OS-1

66.2

2.3

OS-2

n/a

LS-1

63.3

9.7

LS-2

58.3

5.1

TS-1

55.8

2.2

TS-2

55.8

6.2

Mod. IITRI Strength [ksi] 70.3 71.3 62.9 58.5 63.2 59.3

0.188" Hole CoV [%] 4.4 4.3 7.7 5.5 3.8 3.2

Mod. IITRI Strength [ksi] 68.7 46.8 61.8 60.2 56.3 59.2

0.250" Hole CoV [%] 6.1 8.2 4.1 7.5 3.7 6.3

Mod. IITRI

0.375" Hole

56.6

14.4

61.5

2.3

51.6

9.4

Strength lksil

Coy I%1

51.3

2.1

53.6

4.4

49.2

5.4

58

Figure 8.8

70.0

¢--- 60.0C

50.0[,.-

O

40.0

t'_

Eo 30.0(,.)

o 20.0T¢-,

O 10.0

"-- 0.0

Y//y_/d:iii_i

ii!iii iiiiiiiiiiiiiiiii iiiii !

_:.: x.:,:+:.:+:+x+J_ii:iiiiii!ii!i!!!i:ii!i!ii!iii!

,i::: ::::_::_::;::i::;i:_::;i::l

ii:iii_ii_ii_i.liiii_iiiiiiI_iiiiiii_iiiiiiiiiiiiiiiiiiiiiiiiiiiii_ii_ii_ili!!_!!!!i! i!i:i!i_:i!_iiii_ii!i!!!!i!!!

ii!!!!!ii!iii!i!i_iiiiii_iiii;i!iiii:iiiii!ii!iii:iii_iii:::::::::::::::::::::::::: ============================

i:i:!:i:i:i:i:i_:i:i:_:i'!: :::::::::::::::::::::::::

!ii!iii_ili:i_iii:ii!ili!il!i_i!iiiiiiiiiiiiiiiiii!iii!iiiiii_iiiii:ii:iii!i!i!i.i!: :::::::::::::::::::::::::::::

_i_i_i_i_i_i:i:ii:i!i:i!i_i _!i:;_:i_i:ii!:i:i:!!_!ii!!i

:::::::::::::::::::::: :::::::::::::::::::::::::::::

======================::::::::::::::::::::::::::::

iiiiiiiii!iiiiiiiiiiiii_iilli_i_!ii_iiiii_ili_ii!i!i!i!il

i!_ii_ii:!i_ii!iii:_ili!i!ii i_i!i!ili!ii:ii:ii_iiiiii!!ii

............. ii i iiiiiiiiiiiii !i! i{ii!:....... | ........

iii_i!i_i_i!iiiiiiiiiiiiiiiii!i!

0S-2

i i:_:i_i:i:i:i:!!.!:]:!!:i:

_,+:_x.:+_:,, :-xii!!i!iii!!i!iii!iiiii_iiiii!i:iil}:::::i_ii!_:!ii!!i:ii:i:!i!

iiiiiiili!iiiii!iiiiiiiiiiiiiiiiiiiiiii!iliiiiiiiiiiiiii!iiiii!iii!iiiiiii!ii!i:iiiii!i!ill

iii!i!_ii_iiiiiiii!!i!!!!i!ill

:2:::::::::::::.,.<::;::::_

::::::::::::::::::::::::::::::

iiiiiiiiiii!iii/ /7.1Xi 2

:::::::;:i:i:::::

gi:.iii:,::!!i:.i::i!i:=Y:ii:=i

t ::.:.:::.::+:.::::

LS-1

i:ii::Ti:ii_i!!-ii:!iiiiii:

,i_:i::i_ii_iiiiiiii_iiiiiiiiiiiii

iiiiiiiiiiiii!iiiiiiiiiiiiiiii iiiiii_iiiii_iiiiiii!!iii!!ili_iiiiii!iiiiiiiiiiiiiiiiiiiiii

::::::::::::::::::::::::::::::

iiiiiiiiiiiiiiii!iiiiiiiiiiiii!iii!i!!!ili!iiii!ii_!iiiii!i!

:::::::::::::::::::::::::::::::i:?!?!ii?!:ii!!!?!}!?!!:?i?!)

:::::::::::::::::::::::::::::

iii!iiiiii!iiii!!i!!ii!ii!iiii iiiiiiiiii_ii!ii_2_iiii!iii!

I ...........

kS-20S-1 TS-1 TS-2

Comparison of 1/4" Open Hole Compression Strength for 3-D Woven

Materials.

8.5 Test Recommendation,#

The open-hole compression test methods were analyzed to determine which method

would give the maximum allowable in a manner similar to that which was used to

compare the unnotched compression test methods. For these tests, only material varied,

but here, both material and hole diameter vary. Thus, the normalized mean of strengths

was calculated as follows:

1) Means for each material and hole diameter were calculated with:

1 N

_km = _ Y, Xkmnn=l

where n is the test method number, m the material number, k is the hole size number, N

is the number of test methods and YkmniS the mean for a given hole diameter, material

and test method.

2) A mean deviation from Xkm was calculated for each test method with:

K-- 1 Z aXk.AXn = ._- k = 1

where K is the number of hole diameters and

1 _ Xkmn- XkmA--"_knM m=lz" Xkm

where M is the number of materials for a given test method and hole diameter.

59

Five methods are retained for this comparison: the Boeing Open Hole Compression

fixture, the NASA Short Block, the NASA 1142 specimen, the modified IITRI and the

Zabora fixture. Values of AXkn and AXn are given in Table 8.5 and values of AXn and

mean COV are plotted in Figures 8.9 and 8.10.

The modified IITRI method gave the highest mean strengths (+3%) followed by the

NASA 1142 method (+1%); CoVs were small (<6%) and essentially equal. The CoV for

the NASA Short Block was less than 5%, but the strengths were typically 2% below the

mean. The strengths for the Zabora method were only slightly below the mean, but the

CoV was the highest. The strengths for the Boeing OHC method were the lowest, and

the CoV was next to the highest. As noted previously, the CoVs for the Zabora and

Boeing OHC test methods were very high for the 1/8" thick 2-D braids. All of the other

methods were only used for 1/4" thick materials.

Table 8.5 Mean deviations AXkn and AXn for Open-Hole Compression Test Methods.

Hole Diameter

[inl

0.188

0.250

0.375

AXn

Boeing OHC

-9.1%

-1.7 %

1.0 %

NASA SB

3.4 %

-4.7 %

-5.3 %

-3.2 5

Test Method

-2.2 %

Zabora

-0.4 %

-0.1%

-0.1%

-0.2 %

NASA 1142

-2.3 %

2.9 %

2.9 %

1.2 %

Mod. IITRI

7.0 %

2.2 %

1.0 %

3.4 %

Figure 8.9

¢,-

Eo,.,._

t'-

.o_

111o

4

3

2

1

0

-1

-2

-3

-4

Boeing NASA Zabora NASA Mod.

OHC SB 1142 IITRI

Normalized Mean Deviations for Open Hole Compression Test Methods

in 2-D Braided Materials.

60

Figure 8.10

14

12

10

;iiiiliiiiiiiiilililililili_i_i;i_i_i:::::::::::::::::::::::::::::::::::::

O 6 :::::::::::::::::::::::::::::::::::::

(...) :::::::::::::::::::::::::::::::::::::

..........,..............,...., ,....,...., H, .

2 _!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i=====================================

........-.,...., ........-:.:.:.:.:.:.:.:.:.:.:.:.:.:.:,:-:,:,:

0 :!:i:i:i:i:i:i:i:i:i:i:i:i:i:i:_:_:i:i

Boeing

OHC

CoVs for Open

NASA NASA Mod.

SB 1142 IITRI

:.:-:.:-:-::-:-:-:-..--.-.--.--.

:::::::::::::::::::

::::::::::::::::::::::::::::::::::::::::..,..,.,................................,...............-.......:::::::::::::::::::::::::::::::::::.:.::::::::::::::::::::::::::::::::::::::

::::::::::::::::::::::::::::::::::::::

....., .........., ..................,.,,.,..,...,..........=..............

i::!!!::!::!!!::!=:!!_::i=:i::_!i::i!i!!!!!!!!!

i ....,.., ,... ,....,... ,......,

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

:::::::::::::::::::::::::::::::::::::::

x+x+x+x+:+x.:+:,

:::::::::::::::::::::::::::::::::::::::

:::::::::::::::::::::::::::::::::::::::

Zabora

Hole Compression Test Methods in 2-D Braided Materials.

61

9. In-Plane Shear Test Program

9.1 Test Confiaurations

Three test methods were considered for shear testing as shown in Table 9.1: tube

torsion, a modified rail shear and a compact shear specimen. Tube torsion tests were

conducted at The Pennsylvania State University and all details of the testing can be

found in Reference 7. Special end fixtures were designed for the tube torsion test. These

consisted of an inner metal plug, pressure fitted inside the tube by cooling in liquid

nitrogen, and an outer two part collar clamped around the composite tube. A single

tension bolt is fitted in the center of the end fitting to allow for biaxial tension-torsion

loading, although this feature was not used here. Eight 1/4" by 1/8" strain gage

rosettes were used on the first few test specimens, with that number reduced to four on

later specimens. As indicated in Table 9.1, tubes of two different diameters were tested,

1.25" and 2.33".

The modified rail shear method uses a specimen, shown in Figure 9.1, similar in

shape to the standard rail shear test but in a different fixture. The main difference is that

the fixture consists of two vertical rails clamped to a rigid base instead of being hinged.

Serrated rails and three attachment bolts per side are used for load introduction. All 2-D

braided specimens were 1/8" thick, while all other specimens were 1/4" thick. All

specimens were tabbed with fiberglass tabs.

The third test method uses a compact shear specimen configuration developed by

Ifju. Although similar in concept to the rail shear specimen, the coupon geometry is

somewhat different. A specially developed shear strain gage is used to measure the

average shear strain over the entire test section. The test results presented in this section

can also be found with more details in Reference 8.

Table 9.1 Test Matrix for Shear Properties

SLL LLS LLL LSS Others (1)

Small Tube, 1.25" 8 8 4 4

Large Tube, 2.33" 8 8 4 4

Rail Shear 3 3 3 3 3

Compact Shear 6 6 6 6 4 (2)

(1) Five Stitched Uniweave and Six 3-D Woven

(2) Five 3-D Woven only

62

.L. 4.50 _I

o.a75 iiiii',i)iiiii)i_i_iiiii'_iiii'_iii_iiiiiiiiiiiiiii:.__iiiiii_ii',i:.ii)J)))i)t)))))))j))))i)))lm_ I ..... i........_z

_3.00 t J_L'-- 0 25 DIA ! o o

• • k Strain Gages, 0 ,+45 ,-45°,90 °

Figure 9.1 Rail Shear Specimen and Compact Shear Specimen•

/--- Shear Gage

,/J i I

Niiii iiiiil

::[iiiiii::i::i_ii;ii;iii!iiiii

.25"


Results from the tube torsion tests are summarized in Table 9.2. Because these

specimens were produced differently from all the other specimens used so far, the

normalized thickness could not be used. Instead, an estimated fiber volume fraction was

calculated based on the braiding machine setup, tow sizes and tube thickness. The

measured results were then normalized to the nominal 60% fiber volume used in this

report. The results from the Rail Shear and Compact Shear specimens are shown in

Table 9.3. All these results are compared graphically in Figures 9.2 and 9.3. For [0i/+0j]tape laminates, the shear modulus is a maximum for 0 = 45 ° and increases with

increasing percentage of 0 plies. One would expect the 2-D braids to behave similarly.

Indeed, the shear modulus for LLS (45 ° and 54% braid) is greater than those for SLL (70 °

and 54% braid) and LLL (70 ° and 54%) braid, which are about equal, and the shear

modulus for LSS (45 ° and 88% braid) is greater than that for LLS.

The results contain much scatter. For the shear modulus, the difference between

highest and lowest data is about 45% for SLL, 28% for LLS, 32% for LLL and 36% for

LSS. Similarly for strengths, the differences are 70% for SLL, 73% for LLS, 71% for LLL,

and 77% for LSS. Small tubes and compact shear specimens made of LSS tended to fail

outside the test section and were not included in the calculation of 77%. The LSS braid

was the strongest Of the 2-D braids•

63

Table 9.2 Summary of Tube Torsion Test Results for 2-D Braids

Property SLL SLL LLS LLS LLL LLL

Estimated Fiber

Volume Fraction [%]

Large

51

Small

53

Large

5O

Small

55

Large

46

Small

45

Norm. Strength [ksi] 11.9 11.0 16.5 11.8 11.5 15.3

CoV [%] 8.9 2.4 6.5 4.5 1.6 4.7

Norm. Modulus [msi] 2.18

7.7CoV[%i

1.87

10.0

1.14

7.9

1.35

22.1

1.33

9.7

1.59

6.7

(1) No specimen was failed during test

Table 9.3 Summary of Rail Shear and If

Property

Strength [ksi]

CoY 1%1

Modulus [msi]

CoY [%1

SLL SLL LLS

Rail Compact

18.7 17.6

8.8 3.5

1.51 1.65

4.6 3.7

Rail

18.2

13.9

2.39

5.0

LSS LSS

Large Small

50 56

>25 (1) 18.1

n/a 3.6

3.57 2.90

4.7 28.0

U Fixture Test Results for 2-D Braids

LLS

Compact

19.5

3.0

LLL

Rail

17.3

4.0

1.78

10.4

LLL

Compact

18.9

3.5

1.35

3.1

LSS

Rail

32.0

25.2

3.93

8.0

1.94

3.7

LSS

Compact

18.9

3.9

3.18

3.3

4.0

3.5

3.0'5E

2.5(,O

"o 2.0O

1.5Or-

091.0

0.5

0.0

Figure 9.2

[] Large Tube

[] Small Tube

[] Rail Shear

[] Compact Shear

SLL LLS

_1 I

LLL LSS

Comparison of Shear Modulus by Various Test Methods for 2-D Braided

Materials.

64

35

3O

25

t-

2OC

_ 15

e-

co 10

5

0

Figure 9.3

[] Large Tube

[] Small Tube

[] Rail Shear

[] Compact Shear

SLL LLS LLL LSS

Comparison of Shear Strength Various Test Methods for 2-D Braided

Materials.

9.3 Stitched Uniweave Materials

Only the modified rail shear method was used for the stitched uniweave materials.

Bearing and shear-out failures at the attachment holes were obtained for all specimens.

Shear modulus was measured and is reported in Table 9.4 and illustrated in Figure 9.4.

Strength is also indicated for reference in this Table in order to provide a lower bound

to the actual shear strength of the material. The use of thinner specimen with a larger

number of attachment holes and with a larger distance between holes and specimen

edge is therefore recommended.

Table 9.4 Shear Properties of Stitched Uniweave Materials

Property

Strength [ksil (1)

CoY I%1

Modulus [msil

CoV [%1

SU-1

21.6

12.7

2.41

0.6

SU-2

20.6

6.5

2.30

7.1

SU-3

21.0

3.7

2.32

3.6

SU-4

22.6

8.1

2.62

1.5

SU-5

20.5

4.7

2.35

1.2

(1) All specimens failed in bearing

65

Figure 9.4

_' 2.5E

¢_ 2"t

"5"o 1,5o

'-_ 0.5

0

:_:_$1:'=i:i:_:!:i:_:!:i.,,,,,.,_...""'"'"""

_'_'..I..........................-------------............,............,.............

ii;...........:i_.:E¢i:i:i¢i:_:_:!:.,,.,.,,...................:..-.x.:._.:.x.:.x.,

_:.::i&'.'.::i:.::;_:_::::.,.,,.........................,......-'"""'"'"-' " '-"'""-""" "

SU-1 SU-2 SU-3 SU-4 SU-5

Shear Modulus of Stitched Uniweave Materials.

9.4 _-D WQv_,n M_terial_

Both the modified rail shear method and the compact shear specimen method were

used for the 3-D woven materials. Bearing failures at the attachment holes were

obtained for many specimens with the rail shear method. Strength and shear modulus

were measured and reported in Table 9.5. Moduli measured by the two methods are

compared in Figure 9.5. A slightly higher value was consistently obtained with the

compact shear specimen. The many bearing failures confirmed that the present rail

shear configuration is not adequate, especially for thick specimens. As in the previous

section, the use of thinner specimen with a larger number of attachment holes and with

a larger distance between holes and specimen edge is recommended for the rail shear

method.

Table 9.5 Shear Properties of 3-D Woven Materials

Test

Rail

Shear

Compact

Shear

Property

Strength [ksi]

Coy l%l

Modulus [msil

CoV 1%1

Strength lksi]

CoY I%l

Modulus lmsil

CoY I%1

OS-1

13.8 (1)

37.6

0.57

2.7

10.1

2.6

0.72

3.9

0S-2

20.4 (2)

5.5

0.54

1.7

n/a

n/a

TS-1

12.7(1)

0.7

0.62

7.9

11.2

2.7

0.77

2.3

TS-2

11.3 (2)

22.2

0.71

2.7

11.3

0.8

0.83

6.9

LS-I

8.0

3.8

0.73

5.2

9.7

2.6

0.85

6.4=

(1) One of three specimens failed in beanng

(2) MI specimens failed in bearing

LS-2

9.1

2.1

0.70

4.1

10.2

1.5

0.81

4.7

66

0.9

0.8

._- 0.7E 0.6

0.5O

0.4

0.3e-

0.2

0'110

Figure 9.5

iiiiMi! _ ..............---....... .:.:.:.:.:.:.:

_l "-- :_:_:_:_:_:_:_iiiiiiiiiiiiii !iiii_ili_iii_ iiiiiiiiiiiiii':':':':':':': : ':+:':':':': : : : _:_:i:_:_:_:;

•"'"'"" ::::::: i:i:i:i:i:i:i: ::.::: i!i_ililiiiiii -- :E:i:i:i:i:i:i ::::: i!ii?ii

i i i i' i iii iiii!!',ii!ii',i ................[]i: :!:: !!_!!i_!_i_!i : !!!!!!!!![_!_! : ::::::::::::::-- ::::::::::::::: :: i:i:i:i:i:i:i: ::::::::::::::.... :.............. .....: _:i:i:i;i;i:i:i...........................:............. Rail

: :i:i:i:i:i:i:i ...........:,:,:.:.:.:.: : :::::::.. :+:.:,:,:.:,::::5::::::::::::::::: ::::::::::::::................ ::: ::::::::2:::!i!iiii!!iiii! !!i!!!i!i!iiii ::.:! :::;::::::::::: : !:!:!:_:!:!:!: : : :':':':':':':"

:::::' _i!!ii_ii_ii_.... :i::;: i_i[iii_iiiii_!:;;;;i;iiiiiiiiiiii!:_: _!_i_i_i_i_i_i:::: iliiiiiili!ii{ [] Compact....... : :i:i:!:!:i:i:i : : ..............:::: ', ::i::iii::::iil;:_ :: ........................................

:_::::_ ..............: ;; ..............: :. ii::il;:iiiil;:il:: iiiiililililil

•...... .:.:.:.:.:.:.: ..............

iiii',iiii!',iii, iiiiiiiiiiiill:::: :: iiiiiiiiiiiiii!iii!!iiiiiii!.............',',',','.','1 ....

OS-1 OS-2 LS-1 LS-2 TS-1 TS-2

Shear Modulus of 3-D Woven Materials with Rail Shear and Compact

Shear Specimen Methods.


The in-plane shear test methods were analyzed to determine which method would

give the maximum allowable in the same manner as the unnotched compression test

methods in Section 7.5. All the rail shear specimens for stitched uniweave and some 3-D

woven materials failed at the attachment holes and those strengths could not be

included in this analysis. Values of Axn for strength and modulus are given in Table 9.6

and values of AXn and CoV are plotted in Figures 9.6 and 9.7. In general, the rail shear

and compact shear tests gave the largest mean values of modulus and strength and the

smallest CoVs for modulus and the largest CoVs for strength. The modulus CoV was

smallest for the compact shear specimen. A special strain gage was used for the compact

shear specimen that extended across the entire 0.75" test section. Likewise, the modulus

CoVs for the tubes and rail shear specimens would probably have been smaller had

larger strain gages been used. It was not expected that the tube specimens would give

the lowest values of strength because tubes have no free edges and are believed to have

the most uniform state of shear stress. However, the difference between manufacturing

methods for the tubes and flat plates could have caused the strengths for tubes to be less

than those for rail and compact shear specimens. Therefore, it would probably be best to

use a tube torsion test for braids that will be used for closed section structures and rail

shear or compact shear specimens for braids that will be used for open sectionstructures.

67

i

Table 9.6 Normalized Mean Deviations AXn for Shear Test Methods

Property

Large Tube

Strength -16.3 %

Modulus -1.8 %

Test Method

Small Tube Rail Compact

-21.7 % 17.8 % 22.5 %

-9.9 % 13.6 % -1.9 %

t-o

,m

a_ar-ca

15

10

5

W-5

-10

Large SmallTube Tube

Figure 9.6

Modulus ..............

I!!!i!!!!!!!!!!!!!!!!!!!!!ii]_iEili_!i!i!!!i!!i!.............

L .............

!_!i!E!_!_!!!!!!!!!!!!!i!!:i:i:i:i:i:i:i:i:i:i:i;i:i C:;ilililililil;iiiilili;iii .9,.....,...,.,.....,......,

!_i_i_i_i_i_iiiiiii!i_ii!_i _::::::::::::::::::::::::::

?]:_:E:!:_:_:i:[:i:i:i:i q_'I a, vvv];;i ,

i:i:]:!:i:i: I i . t-

::::::::::;: 1 ca

:!!!!!!ii!i!i

,...,.,,.,,,

i:!:!:!?!:i

Rail CompactShear Shear

3O

10

0

-10

-20

-30

LargeTube

I

Strength

!::i}!!i!::!::!i!i!::!!!!!::::

_i!!!!!!!!!!!!!i]!_!!i_!!!

|!:!:!:!:!:!:!:?:!:i:i:i:

I " .......... I I

Small Rail CompactTube Shear Shear

Mean Deviations for In-plane Shear Test Methods.

>oo

14

12

10

8

6

4

=. -...-.......

.!!!!!!!!."-'!!!!!!i

• l!i!i_i}]ii]ii_::|!!i!i:-!!!!!i!]f

"!i}!i!i#!!

2 i_iI_i_i_i::oLargeTube

Figure 9.7 CoVs for

Modulus:!!!i!i!i!i!i...........

..................... •

i!!!!!!!!!i!]...........:.:.:.:.:.:

...........

...,..,.,,.

............

............

............

,.........,. -.-...-.-.....- -.-.-.-.-....... •., ...., ........,...,.,,

!:i:!:E:i:i: 2222ZZ2ZZCIZI

""'"' """"""""" I

............ ...z.-...................•....z..... ....,.............,............,..,... .............

............ !iii!ili!i!i}!i!i!!!i!illiiii!i}i!.......................................,..............................,...........z.-.....

.,..... ,.,. .............:.:,:.:,:,:,

:i:i:i:i:!:iI l lllll

I

Small Rail

Tube Shear

>oo

I I

CompactShear

14

12

10

8

6

4

2

0

In-plane Shear Test Methods.

LargeTube

Strength

I

Small

Tube

...z..,..............-..,

:.:.:.:.:.:.:-:.:.:.:.:.:.

-:':':':-:':':':':-:':':':......-...................

i!!!!!!!!!!!!!!!!!!!!}!!!!

-:-:-:-:-:-:-:-:-:-:-:-:-:

_i_!!i_!_!!]!!!!!!!!!!!!!!!_i!![!_!_!_!!!!!!i][!!iii_i}!i!i!i!i!i_i!i!i!i!}ili!iii!!i!i!i!i!i!i!iii!iii!i!_!_!?!!!!!!!!]!!!!!!!!!!!

III

Rail

Shear

I I

CompactShear

68

10. Filled-Hole Test Program

Past experience with composite laminates has shown that installing a fully torqued

fastener in an open-hole specimen often reduces the notch tension strength and thus

makes this condition critical for design considerations. The likely cause of that effect is

that the clamping force of the fastener induces through-the-thickness compressive

stresses around the edge of the hole which delay the onset of delamination. Since

delamination tends to reduce the stress concentration in the longitudinal fibers adjacent

to the hole, reducing delamination decreases strength. Therefore, a limited test program

was conducted to verify if this was also the case with the materials considered in this

investigation.

10.1 Test Confiaura(ion

Because of limited material availability, only three of the 2-D braids were used as

indicated in Table 10.1. The same specimen configuration as in the open hole test was

used with a 1/4" titanium Hilok fastener installed in specimen identical to the open-

hole tension specimen. Once again, the influence of the width to diameter ratio (W/D)

was considered.

Table 10.1 Filled Hole Tension Test Program

Width [inl W/D

1.00 4

1.50 6

2.00 8

SLL LLS

3

3 3

3

LLL

10.2

Results of the test program are shown in Table 10.2. As for the open hole tests, the

simple correction factor for infinite plate width was applied to the strength data. A

comparison of net stress, gross stress and corrected stress is shown in Figure 10.1 for the

SLL material. Results show that the corrected stress is the least sensitive to W/D. Little

difference is seen between W/D=6 and W/D=8, but the result for W/D=4 is slightly

lower (by 4%) than the other two results, thus indicating that a specimen with W/D=6

is sufficiently wide. Filled and open hole strength results are compared in Figure 10.2.

As expected, a small strength reduction is observed with the installation of a fastener,

on the order of 9% for SLL, 14% for LLS and 12% for LLL. This confirms that, as for tape

laminates, filled hole tension is the critical case when developing material design

allowables for the Room Temperature/Dry environment. As in previous tests,

increasing the tow size (going from SLL to LLL) leads to a reduction in strength on the

order of 15%.

69

W/D4

Table 10.2

Property

Stress [ksi]

CoV [%]

Filled Hole Tension Test Program

LLLSLL LLS

81.2

4.6

84.2 71.5

8.7 7.9

84.7

1.7

6 Stress [ksi] 72.0

CoY [%1 2.7

8 Stress Iksil

CoY [%]

Figure 10.1

120

100

80

t::

6O

t-

O 40t-O

_- 20

A t"

Corrected

G ross

Net

I i I

4 6 8

W/D

Comparison of Net, Gross and Corrected Stress for Filled Hole Tension

Test of SLL Braid.

¢1)

t-O

¢-

Figure 10.2

100 -

90--

80-

70--¢-.

60--t-

50-

40--

30--

20--

10--

0 • I

SLL

....,..........,...,.,........-...

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!i!!!!!!!!

:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:.:-:.:.:::::::::::::::::::::::::::::::::::::

,:.:.:.:.:.:,:.:.:.:.:.:,:.:.:.:.:.:.:

...., ,.....,...... ,.,.,.

iliiiiiiiiiiiiiiiiliiiiii:,:.:.:.:.:. x,:+:.:.:.::::::::::::::::::::::::::

i!i!i!i!i!_:!iii!ii::!::!i!::!::::::::::::::::::::::::::::::::::::::::::::::::::::

.........,...............

_i_i_i_ii_ili_i_i_i_!_i__,

-.-.- -.-..-.-.-.-.- -.

:+x+x+>x+:.:::::::::::::::::::::::::

::::::::::::::::::::::::::+x+x<+:+x.:..................

::::::::::::::::::::::::::

::::::::::::::::::::::::::

x+x+:<+x+:.

LLS LLL

[] Open Hole

[] Filled Hole

Comparison of Open and Filled Hole Tension Strength Data for 2-D

Braided Material.

70

11. Bolt-Bearing Test Program

The last in-plane property examined in this investigation is the testing of textile

composites for bolt bearing strength. Although not strictly a material property in itself,

bearing strength is a key parameter for the design of composite structures. Different test

specimens representing various types of joint configurations are typically used for this

purpose.

11.1 Test Confiauratiorl

Three basic specimens, shown in Figure 11.1, were selected for this investigation: the

unstabilized single shear specimen, the stabilized single shear specimen and the double

shear specimen. Because of limited material availability, only the 2-D braided materials

are considered here as shown in the test matrix in Table 11.1. For each test

configuration, the influence of two geometric parameters is examined: the distance of

the hole center to the edge of the specimen and the width of the specimen. Several edge

to diameter ratios (e/D) and width to diameter ratios (W/D) are included. Note that

when testing laminated composites, ratios of W/D = 6 and e/D = 3 are typical. A 1/4"

titanium Hilok fastener is used for all tests. The influence of fastener torque is also

considered in the double shear bearing test: in one series of tests, a fastener with no nut

is inserted in the hole as a simple pin (no clamp-up) and in the other, the installation

torque is doubled to increase clamp-up and possibly induce some damage.

Table 11.1 Bolt-Bearing Test Matrix

W/D e/D SLL LLS LLL

Stabilized Single Shear Bearing

SLL LLS

Double Shear Bearing

4 2 3 3 3 3

4 3 3 3 3 3

4 4 3 3 3 3

6 2 3 3 3 3

3 3 3 3

8 3 3 3 3 3

8 4 3 3 3 3

6 2

6 3

6 4

6 3

Unstabilized Single Shear Bearing

3 3

3 3 3

3 3

Double Shear, Over-torqued Fastener

3 3

Double Shear, Pinned Fastener

3 36 3

LLL

71

o

9 9

o_m-

o_ 8° o_o _i 0

- 44-

/

_o+4

,.a

OulN

Figure 11.1a Baseline Dimensions for Stabilized Single-Shear Specimen.

z

Iite

.o

_i° _0

o_

-¢

N

1,,.

Figure 11.1b Baseline Dimensions for Unstabilized Single-Shear Specimen.

72

Figure 11. lc

|

/o-ac_-auaual-

_ ca o,.

_o_ _

>z

_z_

i

Baseline Dimensions for Double-Shear Specimen.

Ou_

I,-

¢¢

",r

W

m

11.2 2-D Br_id$

When examining load versus stroke test results, non-linearity due to damage

developing around the hole is usually seen prior to final failure. Two load levels are

therefore identified: limit load, which is defined as the load corresponding to a

permanent hole elongation equal to 2% of the hole diameter, and ultimate load which is

simply the maximum load reached during the test. However, for most bearing tests, the

ratio of ultimate to limit load is typically less than the safety factor used for design

(typically 1.5), thus making the ultimate condition more critical. Therefore, in most of

this discussion, ultimate strength will be considered.

Tables 11.2 to 11.4 summarize the ultimate strength and coefficient of variation

results of the various configurations. Strength was calculated as the ratio of load

divided by nominal thickness and hole diameter. In general, all the data exhibited

moderate scatter, with an average CoV of 5.2% for LLS, 2.6% for SLL in the single shear

tests, and an average CoV of 4.9% for LLS and 3.1% for SLL in the double shear tests.

The influence of the specimen dimensions is examined first by looking at the results

for the SLL and LLS materials. The first test considered involves the stabilized single

shear specimen. As shown in Figure 11.2, W/D appears to have little or no effect on

strength. On the other hand, the edge distance (e/D) has a definite effect on the results.

73

In all cases, a ratio of e/D=2 leads to much lower strength. For the SLL architecture,

little or no difference is seen between e/D=3 and e/D=4. For the LLS architecture, a

slight increase is seen when going from e/D=3 to e/D--4, possibly due to the fact that

the unit cell size of this material is about 2.5 times larger than for SLL. The very same

conclusion is drawn for the unstabilized single shear test shown in Figure 11.3.

A different behavior is seen for the double shear bearing test as shown in Figure

11.4. For both SLL and LLS, ultimate strength continually increases with increasing e/D.

Limit strength is seen to be much less dependent on e/D. This is due to the fact that

local bearing failure occurs first, followed by a progressive shearing out of the fastener.

In specimens with larger edge distance, failed material tends to accumulate between the

loading plates, delaying the final shear-out failure and increasing strength.

Finally, the results of all test configurations with W/D=6 and e/D=3 are compared

in Figure 11.5. The lowest bearing strength is obtained for the pinned double shear

specimen for which no load is transferred through friction. At the opposite end, the

double shear bearing strength is the highest. However, this type of bolted joint

configuration is not the most likely in typical structures. The stabilized single shear

specimen is usually considered to be more representative and gives slightly higher

results than the unstabilized configuration. Using the stabilized single shear as a

baseline, the pinned double shear is 18% lower for SLL and 2% lower for LLS; the

unstabilized single shear is 10% lower for SLL and 7% lower for LLS; and the double

shear is 42% higher for SLL and 48% higher for LLS. The difference between SLL and

LLL is about 9% for stabilized single shear due to the increased tow size.

120 SLL 120 LLS

W/D=4

---"_ID_ W/D=6

-----"0"_ W/D=B

0 0

2 3 4 2 3 4

Figure 11.2

e/D e/D

Effect of W/D and e/D on Stabilized Single Shear Bearing Ultimate

Strength of 2-D Braided Materials SLL and LLS.

74

120

•"_' 100

8009

60

.-= 40f=..

m 20

0

2

Figure 11.3

SLL 120 LLS

•"_' 100

80t.t)

60O)

._- 40t,_

rn 20

0

,,,,_

I I I I

3 4 2 3 4

e/D e/D

Effect of e/D on Unstabilized Single Shear Bearing Ultimate Strength of 2-D Braided Materials SLL and LLS.

160

14oI _" 120 :- -- "--2-'__"-: _'-- 2_'7'7""8

,_ _oo

r_ 80O')"- 60t_

'_ 40£D

20

0 t I

3 4

W/D=4 Ultimale

W/D=6 Ultimate

W/D=8 UIl:t mate

----.O--- W/D=4, Dmll

---.._--- W/D=6, Limil

----_--- W/D=8, Limrt

Figure 11.4.a

e/D

Effect of W/D and e/D on Double Shear Bearing Ultimate Strength of 2-D Braided Materials SLL.

75

160

140

120

100

8O

60

4O

20

0

'5

_=.__ ¢¢.-_-.--.-;- - v -

I I

2 3 4

e/D

,._--,--O-_-- W/D=4, Ultimate

._---,-O---_. W/D=6, Ultimate

.-_W/D=8, Ultimate

- - - -0 - - - W/D=4, Limit

- - - "a - - - W/D=6, Limit

- - - .._- - - W/D=8, Limit

Figure 11.4.b Effect of W/D and e/D on Double Shear Bearing Ultimate Strength of 2-

D Braided Materials LLS.

00.a¢

¢-

O')c-

coo_c-

-t-

in

Figure 11.5

160

140

120

100

8O

60

40

20

0

I

Double

Pinned

Unstabilized Stabilized Double

Single Single

Comparison of all Bearing Tests with W/D=6 and e/D=3 for 2-D Braided

Materials.

76

Table 11.2 Stabilized Single Shear Bearing Ultimate Strength Results for 2-D Braids

SLL LLS LLL

W/D e/D Strength [ksi] CoV [%] Strength [ksi] CoV [%] Strength [ksi] CoV [%]

4 2 87.5 0.5 61.7 10.6

4 3 98.3 3.8 88.8 3.2

4 4 102.4 1.1 94.7 1.8

6 2 90.6 4.6 70.9 5.4

6 3 103.1 1.0 83.6 13.0 91.0 2.4

6 4 103.4 3.1 89.0 2.9

8 2 80.2 5.6 65.8 6.4

8 3 98.0 1.7 87.5 0.3

8 4 100.2 2.2 93.6 3.3

Table 11.3 Unstabilized Single Shear Bearing Ultimate Strength Results for 2-D Braids

SLL

W/D e/D Strength [ksi] CoV [%]

6 2 80.0 2.9

6 3 91.7 5.6

6 4 90.6 3.7

LLS

Strength [ksi] Coy [%1

3.2

LLL

Strength [ksi] Coy I%1

64.6

80.8 3.1 87.3 12.1

84.7 5.8

Table 11.4 Double Shear Bearing Ultimate Strength Results for 2-D Braids

W/D e/D

4 2

4 3

4 4

6 2

6 3

6 4

8 2

8 3

8 4

Pinned Fastener

6 I 3 I

SLL LLS

Strength [ksi] CoV [%]

119.7

Strength [ksi]

101.43.1

136.5 5.6 129.1 2.8

156.9 3.3 143.5 3.3

111.5 3.9 98.4 4.1

136.5 2.6 124.4 11.7

148.6 4.1 154.8 2.3

110.2 1.2 101,7 9.8

134.9 1.8 124.0 1.1

148.1 2.7 137.0 6.8

83.2 11.2 87.4 7.5

Over-torqued Fastener

6 [ 3 I 142.5 7.6

CoV[%l

2.1

77

12. Interlaminar Tension

The interlaminar tension strength of 2-D braided and 3-D woven specimens was

determined using two specimen configuration, a C-shaped specimen and a L-shaped

specimen.

12.1 Specimen Confiourations

Both configurations rely on the same mechanism, the application of a bending

moment around a curved geometry, to generate an out-of-plane tension loading in the

specimen. The first configuration is a C-shaped specimen illustrated in Figure 12.11' As

shown in the test matrix in Table 12.1, four combinations of width and midplane radius

are used. The braids marked "-2" and "-3" are variations of the basic architectures used

in the previous test programs. The characteristics of these architectures are shown in

Table 2.1. The second configuration is a more common L-shaped flange bending

specimen, shown in Figure 12.2. Only one size specimen was used to test both 2-D

braided and 3-D woven materials. For both specimens, the attachment to the test

machine included hinged joints arranged such that the bending moment in the

specimen radius can be easily determined by multiplying the load by the offset from the

load application line to the radius.

For both test results, moments were converted to interlaminar stress with the

simplified formula based on beam theory (see for instance Reference 9):

3.M

Ozz - 2 • R. t

where M is the bending moment per unit width, R is the midplane radius and t the

thickness.

A more exact solution for an homogeneous orthotropic solution is give in Reference

10. Using that analysis, the calculated value for the peak interlaminar stress would be

3.3% higher for the C1 configuration, 7.8% for the C2 one and 8.1% higher for the L

specimen. However, given the highly inhomogeneous nature of the material tested, it is

not very clear whether the more exact solution is actually more accurate.

Config

C1-1

C1-2

C2-1

C2 -2

L

Table 12.1 Interlaminar Tension Test Matrix

Thick. Width Midplane SLL

[inl [inl Radius [inl

0.13 1 0.255 3

0.13 2 0.255 3

0.17 1 0.305 3

0.17 2 0.305 3

0.25 2 0.315 3

LLS LLL LLS-2 LLS-3 SLL-2 3-D

Weaves

3 3 3

3 3 3

3 3 3

3 3 3

6 3 3 3 3 3

78

Figure 12.1

I/4-28 _ _'_--_ _

HYME JOINT_"_r

L___.

Interlaminar Tension C-Shape Specimen.

E}.250 (4 Places)

f SPECIMEN

]-4-----.25

L

0.19R

i Ii1 J

Interlaminar Tension L-Shape Specimen.

_ 2.0

Figure 12.2

12.2 2-D Braids Materials

A summary of the average ultimate out-of- plane tension stress from the C-section

out-of-plane tension test is shown in Figure 12.3 and Table 12.2. Coefficients of

variation were large, up to 24%, although not uncommon for this type of testing.

Failures were visible as interlaminar cracks in the radius, sometimes along many layer

interfaces, although there was no consistent location of the failures through the

thickness: some were nearer the inner radius, others nearer the outer radius. The

waviness of the layer interfaces caused by the textile architectures was clearly visible

along the crack length. Considering the scatter, there appears to be little influence on the

results from the width of the specimens. The results from the 90 ° flange bend out-of-

79

plane tension testsare shown in Figure 12.4and Table 12.3. The 2-D braided specimens

all failed as intended by out-of-plane tension in the radius, which was visible by

interlaminar cracks in the radius, often along many layer interfaces.

"The strength values obtained with theC-shape specimens ranged from 2.5 ksi to 4.3

ksi, while these obtained with the L-shape were higher, ranging from 3.6 ksi to 4.8 ksi.

These values are similar to those measured in laminated specimens. As reported in

Reference 9, where an AS4/3501-6 all unidirectional L-shape specimen was used, a

definite relation was observed between interlaminar tension strength and specimen

thickness, with the strength decreasing for increasing thicknesses. Reported values

ranged from 11.8 ksi for a .077" thick specimen, to 2.5 ksi for 0.26" thick specimen. The

main cause for that effect was attributed to the fact that the laminate quality in the

radius area tends to degrade with increasing thickness due to the manufacturing

process.

Table 12.2 Interlaminar Tension Strength Measured with C-Shape Specimen

SLL LLS-2 LLS-3 SLL-2Config.

C1-1 Strength lksi]

CoV [%]

3.0

17

3.2 2.9

15 11

2.5 2.7

5 10

3.4 4.0

18 7

3.1 3.7

1 24

3.2

16

C1-2 Strength [ksi] 3.0 2.8

CoV I%] 9 11


CoV [%] 6 13


CoV [%] 8 8

s "_ 1 [

Figure 12.3

4

cD¢-.o 3¢-

c 2D..

9

0 1

iJl Config. 1, 1" WideConfig. 1,2" Wide I

[] Conlig. 2, 1"Wide I

[3 Config. 2, __Wide F-_ J------..... i

_ .1___ _1__ __-L

IJIT

| 11I-!EIliF II',1

II

SLL LLS-2 LLS-3 SLL-2

Interlaminar Tension Strength Measured with C-Shape Specimen.

80

Table 12.3Interlaminar Tension Strength Measured with L-ShapeSpecimen

Config.

L Strength [ksi]

Coy [%J

SLL LLS LLL TS-1 TS-2 OS-1 OS-2 LS-1 LS-2

4.8 4.2 3.6 2.2 3.0 3.5 2.9 2.7 2.2

17 12 5 5 9 5 6 16 4

Figure 12.4

5

4

•a 3

2

O 1

0

SLL LLS LLL TS-1 TS-2 08-1 0S-2 LS-1 LS-2

Interlaminar Tension Strength Measured with L-Shape Specimen.


The 3D angle interlock specimens failed by in-plane tension at the inner radius, with

some evidence of out-of-plane tension or interlaminar shear failures as well. Some of

these specimens also had compressive in-plane failures on the outer radius. Therefore,

all the values shown in Figure 12.4 and Table 12.3 should be considered lower bounds

to the actual strength.

81

13. Interlaminar Shear

The interlaminar shear strength of the 2-D braided material and 3-D woven material

was determined using two specimen configurations, the Compression Interlaminar

Shear (CIS) specimen and Short Beam Shear (SBS) specimen.


Both specimen configurations are illustrated in Figure 13.1. Three specimens of each

material system were tested as indicated in Table 13.1. All Compression Interlaminar

Shear specimens were tested in a modified D695 compression fixture shown in Boeing

specification BSS 7260 (see Appendix C). The load rate was 0.05 inch per minute. The

shear stress was calculated assuming a uniform shear stress distribution:

P_xz --

d-w

where P is the ultimate load

w is the specimen widthd is the distance between notches

All Short Beam Shear testing was performed according to ASTM D2344. A small

flexure fixture with 1/8" diameter support rods, 1/4" diameter loading rod and a 1.0:

span was used. The load rate was also 0.05 inch per minute. The shear stress was

calculated assuming a parabolic stress distribution through-the-thickness:

0.75. P'_xz --

w.t

where P is the ultimate load

w is the specimen widtht is the thickness

T- I-. 1.5"

TI II.5" i i

_K__ iI

m ' U _I_ 3.2"x ,,\\l,\\\\lx\\\xr,, \\\ Y

1.o"--"1 xFigure 13.1 Short Beam Shear and Compression Interlaminar Shear Specimens.

82

Table 13.1Interlaminar Shear Test Matrix

Config. Width

[in]

CIS 0.5

SBS O.5

Length Thickness SLL

[in] [in]

3.2 0.25 3

1.5 0.25 3

LLS LLL LSS 3-D

Woven(l

3 3 3

3 3 3

(1) Six configurations, OS-1, OS-2, LS-1, LS-2, TS-1, TS-2.

13.3 2-D Braided Materi_ls

A summary of the average interlaminar shear stresses from the Short Beam Shear

and Compression Interlaminar Shear tests is shown in Figure 13.2 and Table 13.2. The

failures for the short beam shear specimens occured in the y-z plane at either the left or

right support rod. The failures for the compression interlaminar shear specimens

occured in the x-y plane between the notches. The shear failures were generally along a

layer of fixed yarns (braid) or along a layer of warp yarns (weave), although

occasionally the crack jumped between interfaces. Some specimens broke into two

pieces showing the wavy failure surface due to the textile architecture.

The main conclusion from this set of tests is that the short beam shear test gave

consistently higher interlaminar shear strengths than the compression interlaminar

shear tests by about 20% on average. Coefficients of variation were lower as well. These

values are somewhat low when compared to comparable laminated material systems

where interlaminar shear strengths in the range of 12 ksi to 17 ksi are typical.

12

_" 10

8

6r-

42

0

I I ' -I I I I

@ Short Beam ShearCompression Interlaminar Shear

Im I I I 1 I

IIWLJ illl Iml I

I I I I

I I I

1 I_t_N,N."]I I_Wx\NI I_N. x] I_\x,_[ I mmlN.N.NII_ml_ x,"

I

P

i

SLL LLS LLL LSS TS-1 TS-2 OS-1 OS-2 LS-1 LS-2

Malerial

Figure 13.2 Interlaminar Shear Strength Measured with Short Beam Shear and

Compression Interlaminar Shear Test Methods

83

Table 13.2 Interlaminar Shear Strength in 2-D Braided Materials

SLL LLS LLL LSSConfig.

CIS

SBS

Strength [ksi]

CoY [%]

Strength [ksil

CoV [%l

5.2

12

7.4

5.5

7.2

10

9.0

1.9

6.0

5.3

6.2

11

6.9

10

7.3

6.7

13.3 _-D Woven Materials

A summary of the average interlaminar shear stresses from the Short Beam Shear

and Compression Interlaminar Shear tests is shown in Figure 13.2 and Table 13.3. The

failures for the short beam shear specimens were like those of the braided materials

except for the three OS-2 specimens, which failed in tension on the lower surface.

Significant permanent deformation was visible after the loads were removed only for

the OS-1 and OS-2 specimens. The failures for the compression interlaminar shear

specimens were also like those of the braided materials between the notches except for

one OS-2 specimen, which failed in compression at the two notched sections. A

replacement from this group was tested which failed in shear.

Much as for the braided materials, the short beam shear test gave consistently higher

interlaminar shear strengths than the compression interlaminar shear tests by about

27% on average. Also the OS-2 material appears to have a higher interlaminar shear

strength than the other materials and different failure modes.

Table 13.3 Interlaminar Shear Strength in 3-D Woven Materials

Config. TS-1 TS-2 O,%1 0`%2 LS-1 LS-2

CIS Strength [ksi] 5.3 6.3 4.5 9.5 6.6 6.2

CoV [%] 9.4 6.6 15 22 7.2 11

SBS Strength [ksi] 8.2 8.1 7.0 9.7 6.6 7.5

CoV [%] 5.0 1.8 1.2 4.9 9.2 8.4

84

14. Interlaminar Fracture Toughness

The mode I and mode II interlaminar fracture toughness of the braided materials are

examined in this chapter. These were determined using the Double Cantilever Beam

(DCB) and End Notch Flexure (ENF) test configurations.


Four 2-D braided architectures were used in this test program. Three specimens of

each kind were used as indicated in Table 14.1. The braids marked "-2" and "-3" are

variations of the basic architectures used in the previous test programs. The

characteristics of these architectures are shown in Table 2.1. All specimens were 0.5"

wide and 0.25" thick. In all cases, the delamination was propagated along the 0 °direction.

All Double Cantilever Beam specimens were tested according to Boeing specification

BSS 7273 (see Appendix C). A bonded block hinge was used to load the specimen

instead of the triangular grips specified in BSS 7273. The edge of the specimen was

painted white to illustrate the progression of the crack more clearly. The crack was

initially extended by 0.5 inch to move the crack tip away from the effects of the Kapton

tape used to form the initial crack. A crack approximately one inch long was extended

three times for each specimen. The load rate was 1 in per minute. The actual crack

length was measured with calipers and the area under the load-displacement curve was

calculated by the test software. Both the area and initiation methods were used to

calculate the mode I fracture toughness GIc:

Area Method:

GI c _ E (in. lb / in 2)A.W

Initiation Method:

GI c = 3-P- Y (in. lb / in 2)2.W.a

where E is the area under the load-deflection curve

A is the increase in crack length

W is the specimen width

P is the peak load prior to crack extension

a is the crack length

Y is the deflection corresponding to P

All End Notch Flexure specimens were tested in a small test fixture with 1/4"

diameter loading rods and 4" span. The load rate was 0.1 in per minute. The crack was

initially extended in flexure by 0.5 inch to move the crack tip away from the Kapton

tape used to form the initial crack. The crack was extended three times for each

specimen. The compliance was calculated from the actual slope of the load-deflection

O___.-(>Q,.

85

curve between 33%and 66%of the ultimate load for eachcrack growth. The actual cracklength was recorded for eachcrack but a nominal crack length of 1 inch was used in thecalculation as specified. The values for GIIc were calculated with the equation given inthe specification:

GIIc

where

= 9.a 2.P2-C (in.lb/in 2)

2.W-(2.L 3 + 3.a 3)

C is the compliance

L is half the length of the loading span

W is the specimen width

P is the peak load prior to crack extension

a is the crack length

Table 14.1 Interlaminar Toughness Test Matrix


DCB 3 3 3 3

ENF 3 3 3 3,.

Note: Each specimen tested for 3 crack extensions

14.2 2-D Braided Materials

Results for the mode I fracture toughness tests are shown in Table 14.2 and Figure

14.1. The scatter in the results is extremely large, especially considering the fact that 15

repeats of each test were conducted. The average values themselves are extremely high

compared to the typical values measured in laminated composite materials (by a factor

of 3 to 5). The results from both the area and initiation method gave comparable results

considering the scatter in the results. There appears to be some correlation between the

bias fiber angle and the toughness: the two architectures with 70 ° bias angle gave much

higher results than the ones with a 45 ° angle.

The probable cause for these high values is that the crack did not propagate in a

resin-rich layer between plies as in a laminate. Although the 2-D braids are still formed

by putting down successive layers of material, nesting of the different plies does occur.

When looking at the edge of the specimen, the crack path was not straight but rather

followed a "scalloped" pattern going around the tows. Also, when examining the

surface of the delamination, it appears that failure did not progress between layers of

material but inside a braided layer. Parts of the same bias tow were observed on both

sides of the fracture surface, with a thin layer of the tow on one side and the majority of

the tow on the other side. This also implies that some fiber breakage must occur where a

bias tow on the surface of a braided ply enters the ply to pass underneath the other

tows. That could significantly increase the energy necessary to separate the material,

much as fiber bridging in tape laminates.

86

Results for the mode II fracture toughness tests are shown in Table 14.2 and Figure

14.2. As above, the scatter in the results is extremely large, especially considering the

fact that 15 repeats of each test were conducted. The energy release rate values are also

two or three times higher than for tape laminates with similar resin systems, much forthe same reason as for the mode I results..

Table 14.2 Interlaminar Toughness Test Results

Area Method

Gic [in-lb/in 21

CoY I%1

Initiation Method

Gic [in-lb/in2]

Coy !%1

GIlc [in-lb/in 21

CoY [%1

SLL

7.03

33.2

7.89

40.5

13.1

21

LLS-2

4.72

38.1

4.72

20.8

13.4

17

Note: Each specimen tested for 3 crack extensions

LLS-3

4.49

17.7

5.19

20.8

11.6

19

SLL-2

7.43

33.7

7.18

13.2

14.4

20

Figure 14.1

8 • Area7

6 • Init.

5

4o 3(.9

2

1

0


Mode I Fracture Toughness in 2-D Braided Materials.

Figure 14.2

¢M

¢.-

0t-

O

16

14

12

10

8

6

4

2

0 I I


Mode II Fracture Toughness in 2-D Braided Materials.

87

15. Conclusions

Only the main conclusion from each test program is briefly summarized here.

Because of the large variety of tests conducted, the reader should refer to each sub-

section for the conclusions relating to a specific material or test type.

Tension

The main issue in the tension test program was the effect on strength of the specimen

size compared to the material unit cell dimensions. Little or no effect on strength was

observed for the 2-D braids which have the largest unit cells of all material tested.

Therefore, the standard specimen width of 1.5" is recommended.

Open Hole Tension

The effect of specimen width to hole diameter ratio (W/D) was investigated. Results

showed that the standard W/D=6 was adequate.

Compression

A comparison of the Boeing Open Hole Compression, Zabora Fixture, NASA Short

Block, NASA 1142, Modified IITRI, sandwich column, Boeing Compression After

Impact and NASA ST-4 specimens was conducted. The NASA Short Block specimen

and Zabora fixture consistently produced the highest mean strength, but the Zabora

fixture was evaluated only for a limited number of 2-D braids.

Open Hole Compression

A comparison of the Boeing Open Hole Compression, Zabora Fixture, NASA Short

Block, NASA 1142 and Modified IITRI was conducted for hole diameters up to 0.375".

Results show that the Modified IITRI produced the highest mean strength, while the

Boeing OHC produced the lowest. Both the Boeing Compression After Impact and

NASA ST-4 gave good results for larger hole from 0.5" to 1.25".

In-plane Shear

A comparison of tube torsion, rail shear and compact shear specimens was conducted.

Significant differences in both strength and modulus were obtained between these test

methods. The compact shear specimen produced on average strength data 30% to 40%

greater than the tube torsion, while the rail shear method experienced numerous

bearing failures at the attachment holes.

Filled-Hole Tension

Testing was conducted only with the 2-D braided material and confirmed that, as for

tape laminates, filled hole tension is the critical case when developing material design

allowables for the Room Temperature/Dry environment. The standard W/D=6

specimen configuration appeared to be adequate for this type of testing.

Bolt Bearing

Testing was conducted only with the 2-D braided material. As for tape laminates, the

stabilized single shear bearing test with W/D=6 and e/D=3 is recommended.

88

Interlaminar Tension

Testing for interlaminar tension was conducted with the 2-D braided material and 3-D

woven materials using a C-shape and a L-shape specimens. Strength values from the L-

Shape configuration were slightly higher than those with the C-shape specimens,

possibly due to the lesser fiber distortion in the L-shape specimen. The 3-D weaves did

not fail actually in interlaminar tension but showed transverse cracks indicative of in-

plane failure.

Interlaminar Shear

Testing for interlaminar shear was conducted with the 2-D braided material and 3-D

woven materials using the Short Beam Shear (SBS) and Compression Interlaminar Shear

(CIS) specimens. Strength values obtained from the SBS specimen were consistently

higher than those from the CIS specimen.

lnterlaminar Fracture Toughness

Testing for interlaminar fracture toughness was conducted only with the 2-D braided

material using the Double Cantilever Beam and End Notched Flexure specimens.

Results showed much higher toughness in this type material than in conventional

laminated composites.

Observations on 2-D Braided Material

Unnotched tension and compression strength appear to be lower than expected in a

conventional tape laminate. However, in the presence of holes, the 2-D braids appear to

be less notch sensitive in tension. As seen from the comparison of the SLL and LLL

architectures, the larger tow size reduces strength and stiffness, but on the other hand,

the larger tow size can reduce the cost of manufacturing the preform. The transverse

strength in 2-D braids seems to be relatively low in tension, compression and shear.

Since only a limited amount of testing was conducted in that direction, this should be an

area of further investigation.

89

References

1 Falcone, A., Dursch, H., Nelson, K., Avery, W., "Resin Transfer Molding of Textile

Composites," NASA CR 191505, March 1993.

2 Peterson, R.E., "Stress Concentration Factors," Second ed. John Wiley & Sons, Inc.,

Publishers, New York, 1974.

3 Lin, K.Y., "Fracture of Filamentary Composite Materials," Ph.D. Thesis, M.I.T., 1977.

4

5

Masters, J. E., Fedro, M. J., Ifju, P. G., "Experimental and Analytical Characterization

of Triaxially Braided Textile Composites", NASA Conference Publication 3178,

Proceedings Third NASA Advanced Composites Technology Conference, 8 - 11 June

1992, pp. 263 - 287.

NASA Reference Publication 1092, " Standard Tests for Toughened Resin

Composite ," May 1982.

6 NASA Reference Publication 1142, "NASA/Aircraft Industry Standard Specification

for Graphite Fiber/Toughened Thermoset Resin Composite Material," June 1985.

7 McCarty, C.M., "Shear Evaluation of Braided Composite Cylinders,", M.S. Thesis,

Penn State University, August 1993.

8 Ifju, P. G., "Shear Testing of Textile Composite Materials," SEM Spring Conference,

Baltimore, MD, June 1994. Also to appear in ASTM Journal of Composite

• Technology & Research.

9 Seely, F.B., Smith, J.O., "Advanced Mechanics of Materials," Second ed. John Wiley

& Sons, Inc., Publishers, New York, 1952.

10 Jackson, W.C., Martin, R.H., "An Interlaminar Tensile Strength Specimen", ASTM

Standard Technical Publication 1206,1993, pp. 333-354.

90

Appendix A Test Data

All the individual test data are included in this appendix as reported by Intec. Note

that stresses in these spreadsheets are normalized by the actual specimen thickness.

Most specimens are labeled using the following convention: BH2-A-BC-X, where:

A = Material Form 01 = 2-D Braid SLL

B = Task Number

02=

03=

04=

05=

06=

07=

08=

09=

10=

11 =

12=

13=

14=

15=

1 =

2 =

3 =

4 =

5 =

6 =

7 =

2-D Braid LSS

2-D Braid LLL

2-D Braid LSS

3-D Weave TS-1

3-D Weave TS-2

3-D Weave OS-1

3-D Weave OS-2

3-D Weave LS-1

3-D Weave LS-2

Stitched Uniweave SU-1





Unidirectional Properties

Strain Gage Study

Tension Test Program

Open Hole Tension Test Program

Compression Test Program

Open Hole Compression Test Program

In-Plane Shear Test Program

C = Test Type and Configuration (A-Z)

X = Repetition Number

A.1

Tension Test Program

A.2

o

p-

o

uJ

ooz

° )

- 0oo0o_

_-_-_ ,r-

g

g

_°_-

ff. _ ooo

&ul

NNN_,_ mm,,n

111

'000 om

_ o. = o o0,

_c_g,_,-

000"0

°_e,lei ,-I,-

:Q

___.

oo o

a_

_mm

r_

m

O0 o_ o oo o o o oo o o -'0o o o _

•";";.":'"; _,#- °o_ -;- ' -:":. . . .i,

_ ,-" o/' _ _. ......

. .-.._ _, o ._ _,o _:,--

oo _

o0oo o00_o oo0o0 i_o0

m

)ooo oooo ooo

' _

mmm _m _mmm: _mm_' _ "_

o

A.3

,(

=E

E0

! &

u.

,n.._

L"

o

c

"_'- _o ° _ _o oo

_= , ._-._._- ,¢,¢ ,_,_ _,..',_23_ ' '

Oo 0 oooooo _o0oo0

I

• _e.i,_

._!._!E _._oo_ _o_._o _o_o_o _oooo oooo o000 oooc 0 o0oo

• " _6 _

&

_cu _

oo

_, , _ _,_ _m_m

a

A.4

c

o E

11! &

IDI"-

aJ _E_

o

c

o o o o o o oo o o _ oo o o o o o o o

c_

_ _ . ._ . - .,r _ .,_ _Q ._ . . _ ._-- _ _ "7 "- 'rT _, _ _,0_. , _0=_ _ O_ O_ _ _ "7, _1"7, "7, o/. "-,'T "_ "_ "_ _

oooo oooo 0ooo ooo0 oooo oooo oooo

_ <_g =_._ <_ < _ <_g <_ < _d o

>_ OOO ooo 00o _ o Ooo ooo

A.5

i-

_t

"+"++i"Q i,'i _

l, &

x

+.+u.

+m :+

,+ J+_

.¢+

i+-

<:+

:3

{:

!|++

|,,.¢,.+L)

j+

o+.

+_++

iO o 0 o I 0 o oo o

ooOiOo.,Oo(,0 o(+o _ .+_,"

=_.,_,o _.o °o_'°=_e 2'; ° " : "

" o o o {Moo o o o

............ ._o9999 ,'T'T+ "7,I"7, _, "_ "_ , , _;o

- ,_ _ _ _!_.

_N'_ _

=,_..--__-"Sg_-+,

Om " o_gie+_ ......

_0 N N m_ oO_ _ =m mi_ _o m a_

+++++Nm ,N

"5&._

&

o,=,o o -m ++m_ ++ 0 o + Oa o 0 c_O 0'0 O<_ 0 0

_ ,._ ,_ ,_ ,._ _ _ ,._ ,+._ .._ ,,- ,_ ,,_ ._ ._ ._

- -+++__.+_ _._ ++

_o o-- ++_+ioo-

,00o0 oooo

_,.._ +_ , .

--_++- +++++ ++.-----)+.,+_°__,< m, _ __<m_

Z Z

.+++ ...... +++ +°°::= + +++ +++ _+ ++0oo Oo Oo

+++ +++ +++ +++ +++ +++

A.6

_ _ _ -'- o "_" _ t'- ,.o ,._ o _ _ _ o o o _, t0 _ ,._ _n o r. ,.._ o ol o o _ m e... _ t.. o _ "er o o o o o _ o o o 0 c;_ Oo o o o o o o o o o,o o oo o o o

_ _ 0 _ o _ID o o o In 0b _ a>l_ o _e _ _n _n _ o _i

_c

="_ _ " " ' ":4:4 v "v."v "v _ 4 "_[4 _Z oo0, d_ ' .'7"7..'7

_ o o o o o o o ci '0 o 0 o o o 0 c_ 0 o o o o o o

_ ._. _- o_oOoOo_o_oo

I-" 0

-" _ -_. -_ _ _. _0_. _o_.® , - _

u_ I° ° ° oo o oo o oo o oo o

A.7

_== o_

O0 o o 0 o 0-'ooo o "

•_ , "T_-. _._'_ _,'', _ ,_ 'e _. _,'/_

__,_ _

. _._ |_ _h-

._ 'dddd d

_E

° g _" ;I N

a_

NO_ oOO "oO

'' Od_o

(/) u) _

A.8

i-

p-

! A

1--

_._o_o_ .-'-r_-,

---__._ _ - .

_ _,, _ ,

oo000

A.9

i

|_i

Q.

I-

il_°°°° oog_g Ng

._ N • • ._ ..._ ....: .,_ . .

A. IO

¢.-

o E _

0

c_ A"

I--

o_

-v

k2

c

®

e ._5

!z

l

0

_E

o_c

n

ci

rv

Q

E o-c5

Nggg ggN!g _ _

. . . ,_. m,,., ,,',,,,,m .

o 9 9 ,

xm

9

c_

g

.o

o

_2

A.11

.<

r-

.9o6>

(,1

P- _

I"

I)

III'-

I

A.12

ffl

o

O

0J

o

o

II.

,, • u

I,-

_RgO0 O0

es§

OOc:, ....

_'_ _._

_o _ &

111 rn

_ _-

;0

l!_ l!_ ,il_OOOl ooo " '0

&

A.13

Open-Hole Tension Test Program

A.14

_o0

o _ & o

A.15

EO.

o0>

l--

I--

i-

_o

u.

"s

"1"

u3 c_._-. o _c

o __.__m

_n

EE

8

E

u=

_m ¢o 00

,< _ x x x x

-_co ,

A.16

_g

L_g-J

z5_

o

N D

g

t-

@

E E _ =

_" _ _-i,5I--

g

g

_o

c a-

o 0J _

oa_

rr

C]

g_E o

=o_g

ooo _ _ ---

_ 0 _ m;¢,,: t.,,. _ ¢::i

o_o

0 o o 0 000"<5 O06 d 660"0

_ _ _ 0 _ 0 _ 0 0 0 0 0 0

o o o 0 o 00"d (5 c_ 0 d o 0 o0

_c4 e_ e4 o_o_ _ e_ e_oJ e_Jo_

o oo _ o

c_ o_ oJ oi

ooo dO0 do doo

_d&.J

mm

_c4 r_

":I"

O_

0 0 0 t'_ _oLo

NNNN

00oo

_oo oo

gNN, N_i_

g

tD t_ t_

@@@

0.:,0.., o _ o_.-

a3 t,,.. a0 a_

u*l o {n e3

oo o o

0 0

r,l

Ne_

g

0 0 o

_ _ ('31 _ ('_ ¢_ _ t'%l i[_ _ _1 _'3 _ (xI £'3

8 o _ _ o_: _, I_,

A.17

a_

.<

>_<[ h. :_

t-

O

E E

o -_ _

_o

g_m _

UJ ",

g_

121

o_® -8oo .... o

O0 0 0 dO olo 60 OJO Od o 0 oo d 0 O0 o o

;-oolo _o_ o o o oo oo oo0 o 0 0 c_ 0 0 0 d 0 c_ 0 c_ 00 c_ 0 c_ 0 c_ c_ 0 o 0

0 0 0 O0 0 o........ gooo 8988 oooo °o° g0 C) 0 0 O0 0 0 , .

o° g 8 g o° o°

_ _ _ •

o ooo oooOc_ 0 O0 0 C_d 0 " 0 " " 0 c_O 0

, , _ _ _

A.18

}0'1

,¢,

I=

o _._

I"- "t" Q

I--

,.t,,

_o

,.,=I

_e,E

_._z

C

E

Eo(J

_E_-_

o E _

r',

t-', "

,z,

i

E_"6

__E,z_

_r

Q

.... o •

sSS ..._ ,,,

©_e N _88

._. -.': _ _. . ,.-:..,: _

oo°o li i o,_ L-_

_-"1 _r) u" . . .,.;_. _ i:_'_ _;

_ D

o o

_ ..oo_ o_c

9 9

_ rn

-_

1

"'®_r- I

I

o m un o roel I_. ,_ ot'xl m

,,: _ _. <dml

P.- o u" _ od _

OOCO

ooco

8

o

_ m uo o c

9d

:_-

Io

0 0_ .Z; d:

DO O, ,D 04

._o c

:_oc o

"_ o c _

o o o

_ e.. r.mm u

oo (

9o__J .__ _

v

m

A.19

E3

EQ

c @

_m

o0

_o

c LL

x x x .x x', m <" _, m z

A.20

w

EE

3

e,.

I= E ,,,o. '_ Q

± [a_ oF-

_o

"" _ uJ "-

4 u -_o

r5 o o o o oo o':o oo 0"0 oo o o o o o o oo o o

_ ._ p._ _ _ ........

_" c_ o o o Oo o o O0 o'c_ Oo 0"0 o o o 0 o olo

121

_5 -

o c_ c_ 0 0 o

CI_ 30 00 m a_ (]3

A.21

o

E

oo

or_

0r-

1

0

_o

"r

ooo ,oo_

-on0

c_ 666 ooo ooo 0,90

, , --J

a.

rr

_ 0 n z 0

_ o ,

(_ m nn

, , _ "T cxl

O0_J 000

A.22

c-O

b--

0

8

_o

"' _Uj _"

_v

o

S

_v

c

Z

iJi _ii iii

o o o T,._!_c_ o _ _, F _.o_ _ _ _ o o_ _

e_ o_ 0_ 0_ F_N NN2_I_ N _,Fa

ooo, o 8988 8 o

o tn o o _¢I

8 8 g

_ - o

ooo ooo _o

8

F_, 60o 660 moo 6661_-_ ____""" _ . _0, I_o_ _,_ , . . -_-_', . --?,_ _--?,

II:

-- _§_ _

8e6

9o0

121 _ cO 0 nr ffl

- _" _F '_ '_" '_

A.23

a0

0

EQ.

o0=D0

,IBI-

ra

oI,-

E__a

m

m

_o

o_

cLrd _

_" __mz

A.24

• q

b'-

b'-

,nc LL

i-"° _ LLI "-

E "o

8

_ _lr_ _ r,,- Oi ,

_o

_

-- cO

_0o0 0 ooo odo

c N# N __

_5

>if_

u. 0_ _0 _0 _0

, , _. _. _.! _, _. , ,

o0. ooo 990 999 ;_ 9

or

"o ooo

_NN _N_

8 _

_0 ,co

_ ._

_ e

,_,_ _ood Nc_c_

_0 _0

<<, <m <, <, <:

9QO oo.o

I x x x x]

o _ _ _ _o , ,

A.25

i

0

o

I'-

c u-

c 5_Ei cW _.

g-_8

_ ,_ _._,

_ "_- .,,_

ooo"

-_

g_ e

_ NNN

oo l11_

ft.

ge0 "r

en

.

E_

__ _o°

oo o o o _

_. 8

ooo ooo

---

NN_

8 e_ O

_a

RRRco_ _0

;gin

_oo 0

oo o

oo Q

, & &I "r "r I :Z

A,26

iii iii iii iii

A.27

i

A.28

_E

r,- r,- _

c_o_

• m

N

•.- 4., _

oo0

_ .. ,--_a.ell _,_

_ rra_ . u;

_. _ ¢11

_$_o__._. . • _-

P _m

o o

:o0o ooo

!!i¥_.I _'_.¥

_ _:_

x _ x

_n m

A.29

Compression Test Program

A.30

c

b_s

:'- 3:o

c o

m

]=o

A.31

c

..'4

c

|m

ao oo

A.32

!

c

=i

o

I.-

o -_ o'(_ c_ a_ o'c_ ........

<l-- ........Ooolo ,_ 00"0 oooo =00"o (_ 00"0 ooo _c_ oOo

N

8

>u.

A.33

c

m

Jo

|a2

o_ ' o0_- 000 c_ o_ O0 o 0 On O0 © o o_'=0 o o o Oo 0 o 00-'_

_°_,_m m

_=_.

o ........

"T 'T. 'T "T • "T. "T "_. "T

o0o ' ' dO© o0o c_Oo

mo_

8 8 _ 8

o 2 2

o o

N

-°-Oo o

A,34

2"

"i• 0

g

|

;iccl• - c_u

A.35

0..o

_ ou

a.--

p,,...

:, ,.,.

g

|m

E

-i

o 2 --._

tl

Jf_

_->_

cg

@

I

I I i

_= _,'- _,, __ _ _, mJ'_ _., o _, _ et_ mj__'_-- _: _ "_._,_ 0..e-. " g.-t_ "• ,I, , _ , , (_ , ,',_ ap ," ,_1_1

I_,_ _..-_ ,,.: .

0

__ _=_o_

_m

ilRR _ _ gi=:_'• . _:_:_-

o(_o boo ooo

ooo o_

,_.,___._. _._

_ g

i

";0o ooo 0,_o

m _

0 0 0 Q

o "; c oo,o 0oo

.... , <,,(

• _,._"_ _

A.36

A.37

c

E _E_,

A.38

A.39

no

=E

i,--

I-

al

w

• u

c _

o

• o

ooU c'_

S-"

E

g

Q

°" °1_

i

n

_cn

io_ . _ 9

A,40

J

i.-

0

'-; ,.,

c o

J8

== .:_

iI

=_ _; 0 _'_ _ ,0",_ 0 0 _; _. W'-_ 0 - - W _0"_ 0

<_-

J

t,)

'_ oo o

_ Lq

000

_-ii J_-! _i

,,( ,( .(

'T

; == =_

A.4I

f-

| !

u.

c

|m

c__

N._gNc_a_

,2.2.-

gge-

zo

-_ _ ooo

Q

• -_8 .._ . ;_ _-__i_._.-._.... _._._._-"=_..... _ .

m_

........ .'o .... ,_ e._ _" e-"

• .,_ _ .._ ' u_

_ _ _._ _._ _ _

A.42

¢._

! iio .c

..2 (.) is,

i:

I

8

u

g0

. • _,_o-_..i _ _..i,m ..,.;_;o

• K'r;--;_'_ _',,o o;,o'_ _'_;

....... -,_ . _ _ _ _I ---:_r.,,m = _. "e./ Q_._. e,,.....i.,,.: mo_ oo No,_li_ • -

,4 ' ,8 .:'

g Z "

o .,,:'_ _ _'e.: 0 0

_,_ _ _i__ _. _ ,.-.. . [ .

n

,¢1

,_. ,_. ,..:. •

•2___.I_=.

6¢1

• . 0"l:

e_

.'_ ,._

ooo

lS

A.43

p-

i

|m

w

0

j-_a

-__e

g _

A.44

Open-Hole Compression Test Program

A.45

E

c-

o

0

i

k-

o

Q

0

- xw_

c_m

D

o000

0

_iO00 oooo oo_ o

n I_.

O0 ooo

'_ oo0o oooo

dO00 oo_o oooo

A.46

o

0

_s

I-..-

uoi

IS

_JJ fJ! fJf fJfJ_! fJ!

m '

00¢ IO

oo ooo0¢

, , __

m

_o_._

oooio

m _ _,,_

fl

I

!!!

P_e_

X

_ooo

_'_

_'_

-_

t 1

00o

"9

A.47

I!!

j_ t!lJ Ill]! t!li t!]!! ll!! t!t!! li!

_.!i!._._ _,_ ,_ .. _._

,_ _ _ _ _

_ _ -

_OO OOO

"1!!! !ii m

I I

A.4_

Em

o

i--

g

I-.- I11

n•= 1"

0

,.u :_

"5

• - - c

_l

,g-

®g

A.49

EE

Ees

o

:E

F-

w

0

0

_ _oo®

-,_I_. _

D

|_-:oooo_o

c '_ "_o_

_j

0

000'0

o

' Oo o ooo0 o0o0

A.50

E

o

,2

o

G_

E _._

a_

i

' _ _ooo,o oo_ 0 o0o0 ooo o0_ 0 0oo0 00o

3 x_.

'- - c

o

o 0 o o o 0 0

.3 ==

A.51

!

4i

E

o

0 .1:

:i

I

o

i:Ei"

IIz

-- _I c-

!i-• c

!_! l!!

__2_'_o__ .._

I!!

. ._

ooo_o o0o ''i

. oo -_

>_

O0 " "00 "o(=

1!!

I1tIII

!tl

t!I ti! l!!

__'__

o o I=l o oo0o ooo :_ (:l o o

_ o_ _

0 oooo oo_ o oooo

->> ,,_,, "<_,7"_ _. _,_

,,-i ,_ o ...... _; ,_ _;

_ ',._ ', , ,

A.52

,<

E

¢B

:E

8k,- O

_o "6

gI.-

o

:E

iI

u _J

_o

.(

- o 0,0

Z o

8

___ gram

F-

! i

| |

_m'_o_'_'mO_'_¢'_O

_lr

.>>

0 o_ o o O0_io 001o

-

o o o

_ _i •

m _

• _ r,-_O

o 0 o1_ 0 o o_o

o_ioO ,", o o o

_ g

_1 _c_O0' OOc:

o oo

0

ooo

A.53

i! li! iJll_

! _i.__-_:_:_<

_ ooo o

a ,oooo

A.54

A.55

ii tt_ t|t tiJ ttJ iJ_

__:-_:_!'_:_!_- _ .

--_ -. ._ .... =_ ..

A.56

c E

,_ o ,1=

=E_E>

• Sa

N c

eg _

-- o

E

8

000

A.57

|_.

il

!

o_o oOc ,_

® a

A.58

m

e-

c

u.

,y.m

°-_1 -

E_

3

3

>,_

_°r_

_22

_'_o_

OQo

ooo

u_

0

0

o o

_.22

_°°NN

m

o

o m

ooo

0oo

0

0

?

> ¢31

_'

_;° T, .,'

c_Ooi

ooo

0

ooo

_o_I

_N_:

0

222

oood

0o0

ooo

I__-=

lu)

_,

A.59

E

Q._0 _..

iO _o

:E E

i-

®

m

®- i

_5

o_

o

c o

c

oOo

_o__o

o_oo_

r.

co _o_

ooo

e,loQo

m m

m

o

ooo

o r,l _i

sn ¢,1

czn

oo_

ooo

ooo

.r

oo

o oo

5_i

;,3 u'_

_as

mmmmmm

0oo 0oo

o oo_

4['I0 ,

!r- lleI = =

ooo

t_

]9.

_o_

5_oo

o_

N NN_I0 o 0oo_

_ m

o

_mm

m

DDD

_, _

_o

ooo

ooo

Se

ooo

x. zx

g_g

A.60

c

el

_0

"0 m

mQI--

_o

Q

o

Z

c_Lu

uJ

¥

_o_-

_mrr"

o o

OOOoo

,_o_._o__N_oo

e.. _-r_ _

ooo

e_ e_

o o

0

'o

ooo I

"t

_NN

mmu_

55_

0

ffl

6

5o_

_o_

_oo

_55

c_oo

o0o_

]

_o.-

.=o-_

5oe_

Ill

_o

_o

m

ooo

DDD

'_o

_o,--

_-55

A.61

In-Plane Shear Test Program

A.62

c c

EE "_E _

e_ e__JE

&- _

_. _ u_ _ _ u_

=_ -N-

_. ,_

eg_ _NNN

o "_ "_ _ o "_1

,. oo.I

I

J_'_ _ '_i = _1_. _ _, , . ., , . , , ,

!.

_'_ _'_ _

_000 oO 0000

mmmm _

_ ._ _ "_ i_ ._

_, _ I

Eo_c

_2_ _-_

A.63

r-

Eo.o

m

m

)..

i

u

a

G

oo_oo

•r, "7

|oo__

_E

oo

ooo

ili 11_

'0_ " " " o_i_ o o "_

-.o__i_=__=_=_.,__..........

_

0

<, <' <i kk ' _k k_ ' ' " "'"

x _ x ,x = ,x

A.64

c

_> o.°

o

p-

i o

¢§

g

co

C*

S

-!,.!

A.65

Filled-Hole Tension Test Program

A.66

m

,..,r,

"6"r

{X

o

m

A.67

Bolt Bearing Test Program

A.68

l

!.t;m

J

0

JJ|

3

_,_ i|ili_ 111||| 11|11i 1|||||____.._._.__||||||.__11|____

• _-l_f_l_ _,..,..,.I_.__;_.,_._._._ _ ,_._. _ _,.._ ......

_ L'] _ 000000lO C:; :: 0000 ¢_ 0 C:; C_ ¢; 0 (_ 0 G; C_ 0000 CI 0 _ 000000;0 C:; := 000000 _, Z c

I I I !

> _'_°°°°":_ °<_°°0"_°_'_":°°_$'_ ' " " r ...... '1 .....

_1_ _' I_r_ i',_ _" ',r _' '_ ',_ _ _ ,,t ,_, _ ,, _, _ .w_]_i , ]_

,, , , , ltl

_=_, _II1_t=_ = _=_=_ _

I

i , ............. ,...... !_

A.69

P.!!ii

J

!

i£

i

iii

!I

A.70

!!t,.ll

j

j

!!

I

°°i•il oo.

2

tttt!!oooooc

iiiil!

!Jli!i

_1_ i_Iiii

Jii

w_ _ dO

I_1_ _• oo_

_!_

, I °

i

_NNNN_

_ _-_ _

iiii iiiiii iiiiii i_J_JJ iittt! 1tttt! I!oooo _oo_oo oo

JJiilJH"";iliil!!iiii" _-_1 I

_._._-__,_,,_i_I,_._

!!!J!! JJ!!!J !__JJJJ!!JJJJ!

....... ,ooooo,-i ' ooo o_ ' '_ ,

ooooooo_ oooooc o¢_ oooooc_ c_¢_

i!!ii ............

if!iif!! tt ! 1!t!!!!111 1§§§tI11iI §111_11!Il

l

l

#l {_l r.o i#i ¢.'_ ilrl ill ¢t'l¢11 f,l'l _'l (iiI ' o'l o'1 _ ol o'1 QII ¢o _ _ i#l o_

"7''7,'7,'7"7,'7, ......

i_iii_ =+iiiii i_,iiii_,,

iiiiiil_JJ77

l_i|i ig

_._._-

!

i

Ii

_1_ _0000000_

! ° "°!i _ !..... °_'°I{

...... ii_o_-

NNNN_N

!!!!!!

A.71

|!L£

i

o

i

a.

m

iJ

°°!

j_

II

||li

|c

]

]

_ _.

oo-ooii!

A.72

"6

o

A.73

A.74

a:l

o

2_

==m

a=

Q

bo

o

A.75

_= _ ....

=o

_> _ o_i_

.J

m° _ _ _-Q o c_¢;,_

0

ao co a01

z= "_ _

ai

_ =_=_=_

o

I

A.76

Interlaminar Tension Test Program

A.77

rr'

&e-al

rr

0

r_

4p

EEE EEEEEE EEEI __ _ o o o o o _; _ -- _ _ _ _-_

E

A.78

w

n-

l--

:E

"a

o

Q.

_-oo

9. °

•_._._ ,_.E._

_ _---,_

_,__

_1 _O0oOCOooO_

_ _ "_

0 0 0 0 0 _ 0

0 _- _ o_ ¢_ o_

'_:'-- 0 0 ¢:)

if)

o4 _4 ¢'41

i, u.

o o o

U3 U3 tt_

_0 _5 _0

0 0 0

999-7-£ _:en en rn I

9-

o_E

"5

to

A.79

_n

:: 6"6

&o

.., -r

-=5_

IS o __

o

,< c

.=-i o. -

&O3

o; _ ¢0'0;(o r,,. u-) tD i

¢o

Iogg_e

'iN

NNN_ e

9o, 9

"7"7"7

o

0oo

o o o

m

cn _n cn

o

CO --

o

O<

Z

A.80

o

rm

-6

D

i

- 1_ Imm m

, o o o °_ 00 o °_ 0 o 00_ o o o _ o o o,_ _ 0 o o o_ 0 o o _ _

r_ _ 0 o o o _0 o o 0 00 o o dm _ ooo m, O0_ _ OOo_ OOOo_ 0o0

o_ o_ ¢D o _,

z:_: oo o_ ooo 00o Oo o_ 00o_ oO o_ 0oo ,o oo_

_a ooo ggg ggo ggg ooo ooo ooo oo

E _

_D

Z

A.81

• rInterlamma Shear Test Program

A.82

t/I

e

o=u_

&E8

"6

o

r_

Z_

ms

g

_v

_s

O3

,oE-

- _c

_2

03"- E

E

g_

o7

A.83

m

C/)

E

t-o

.0o.Eo0

"6

o

Oo

"o

E. u-' =

oJ

6,

w

o

o_

.cz _" _ ,_

....... _,_._EEE EEE

A.84

(/I

m,-

E

I,..-

I--me

r,,

oe,i

em

-- ..,m

.o

-._oZ" E

®®® _®® ®®® ®®® ®®® ®®®

A.85

._® ®,,® _=_ =....s-- _,

_._ _-_ ooo _!® Q _ ¢" e" ¢" Q 0

" '- -': ®®® _ _0,(,0 (,0 g') F-- t,- I--

_o_° ! _ ;_ _._ o _i,,_ _t:, _

_® _ .........

0o0 000 000

A.86

Fracture Toughness Test Program

A.87

A.88

W

re

z

E.__

i

A.89

Appendix B Typical Stress-Strain Curves

Typical stress-strain data are shown in this Appendix for the 2-D Braided, 3-D

Woven and Stitched-Uniweave materials for a variety of test conditions.

B.1

(/)CO

Figure B.1

120 r .......I

I

!

!

100 ' _ll_"!

'(i!

80 .....I

II

I

60 _ ....

' t!

!!

!

40 _ .... J -I

I

I

I

I

20 _- .....I

I

I

!

0 i , , ,

BH2-01-3A -1

-2000

....... ,....... r ...... 1 ....... ,....... r ...... 1 ....... ,I I I I I I I

I I I I I I I

I I I I II |

iI I I I I

I I I I III I

I I I _lf I I I

I I i I _/ I I I

I I I I I I

I I I I I I I

I I I I I I I

....... I ....... I-------------4 -I- ..... -4 ---------I

' ' i ' "I I I I I I

I I I I I

' ! ' ' ', ....., , , , .---4 ....... I ....... P. .... ----....... I----- ......... --. ----.4 --II

............ I. ...... -4....... I Axial ,_,_I ! I

- i" - Transverse Gage, , , I , , , I , , , I ......... I , , , I

0 2000 4000 6000 8000 10000 12000 14000

Strain [microstrain]

Typical 0 ° Tension Test Strain Data for 2-D Braided Material SLL.

Figure B.2

100

9O

8O

7O

6O

5O

4O

3O

2O

10

BH2-02-3A-3

0

-6000

r ...... 1 ....... ..................... ....... r ...... 1 .......I ! I I I # I

I _ I I I , I I

L -. _ - - - J ....... I .................... a ....... L ...... J ....... II % ! J I I I ;

I i, I _ I I dl_ _ _ "1"_I I _ I

I I I '

I |_ , I _m I I

......._-......,............. I....... _.......--"..... I.......r i

, I '__ , , , .--.41/L/-I,- .... I _

i

I I I I I I _ I

L ...... d _ ._ .... , ............. j ....... i ..... J ....... I

% I I I _ II I I I _

I I I

------_.t-_-----I- -----,------,-------,

I I _ I I I I

I I I II I I

_ I _ I I I I _ I

I I I I I I _

I I ,_ I I I _ I

L ..... .J ....... I. 4 ........... J ..... I _ _ I

_ I I I I Insometer ,_ I I

I I , -- I _

i_ ...... 'I " " ..... I Ilr...... 11 ....... ' ...... 7_ ....... i ..... Ax_Cage

'I '_ I' _t "" ''--/-- -- i ....... !' ........ Tra P-=_'r ...... i ....... =.... -_ • nsverse _e

,' ,' ,' '"'_ '/'l. i : 'i,,.,,,,i,,,_ ' , . . ,, , , I , , , I , , , i , , , ! , , , i

4000 2000 0 2000 4000 6000 8000 10000


Typical 0 ° Tension Test Strain Data for 2-D Braided Material LLL.

B.2

.¢-,

09

Figure B.3

120

100

"ii60 ....

"i!2O

=

0 , ,

BH2_3-3A-3

.............. I....... r ...... 1 ....... I....... r ...... "1....... oI I I I I I I

I I I I I I I

I I I I I I I

I I I I I I I

I I I I I I I

, , , _/ , , I I

....... l....... I- ...... 4_I_-_P lw .... ,....... I- ...... =I ....... ,

I I I I I I I

I I I I I I

I I I I I I I

I I I I i I I

I I I I I I I

....... I............ 4 ....... l....... I- ...... 4 ....... I

I I I I

I I I I I

I I I I I

I I I I I

I I I I I

I I I I

I I I I I

I I I I I

I I I l I

I

• I I I I I, , , I , , , I , , , I , , , I , , , I , , . I , , , I

-2000 0 2000 4000 6000 8000 10000 12000 14000


Typical 0° Tension Test Strain Data for 2-D Braided Material LLS.

(/]

(fJ

Figure B.4

60

5O

4O

3O

2O

10

BH2_4-3A-2

r .... 3 ..... ,..... T ....I I I I

I I I I

I I I I

I I I I

I I I I

I" " * ''_I I ..... I ..... T ....

I _14 I I

I I

I

I

i" .....

I

I

I

I

I

I*----

I

I

I

I

I

I. ....

I

I

I

I

I

I. ....

I

I

I

I

I

=11-

I

I

I

I

I

"1"-

I

I

I I

' ,I I

.... _I_ .... TI .... "I==I

I • I I

i % , i

I • I I

..... ,'.... \," .... I""! I

I I IIi

- - - - -=Ik- -..... I- - I, -,l-

I I • I

, , _! !

I I I l

I I I 11,iii

I I I

I I I

I I I

r ....

i

i

i

i

l

.... T ....

!

I

!

I

I

.... T ....

I

I

I

I

I

.... I ....

I

I

I

I

I

"i ..... i" .... T ..... i ..... i

I I I l I

l l I l I

I l I I I

I I I I I

I I I I I

"1 ..... IP .... T ..... l" "

I I I I I

I I I I I

I I I I

I O I I

I I I I

=I ..... I-- .... • ------I

l I I I

I I I I

I I I I

I I I I I

I I I I I

•=I .... ,I, ..... I ..... I

I I I I

I I I I

I I I I I

I I I I i

I I I I I

=Ii i . * = ,I_ i * = = if= = = . . I

Extensome_er

Axial Gage

........ Transverse Gage

-10000 -8000 -6000 -4000 -2000 0 2000 4000 6000 8000 10000 12000


Typical 0 ° Tension Test Strain Data for 2-D Braided Material LSS.

B.3

35

3O

25

(_ 20

(Jl

•-, 15_0

10

0

BH2_1-3Q-1

............ I" ........... i ............ i ........... "1 ........... '1

! I I ! I

I i I l I

I I , | I ,, i

I I / I I |

............ I-- ........... _iiiiJ .......... ! ........... -=ll ........... '4

I ! l ! I

| I I I I

I I I l

I I I I I

............ I=, .......... I ............ I ........... ..I ........... J

I I I I I

! I ! l I

l I ! l I

! I I I I

............ [_ ...... i........... J ........... J

! ! l l I

I I I I I

................... "--'I" ........... $'--" ........ '=I .......... ""

I I I

I | I I

I I I I

I I I I

/i i.........I I I I

I I I I

........... I- ........... I............ I........... =4 ...........

I I I I

I I I I

I I I I

, , , I , , , I , , , I , , , t , , , I

0 2000 4000 6000 8000 10000


Figure B.5 Typical 90 ° Tension Test Strain Data for 2-D Braided Material SLL.

callfall

16

14

12

10

8

6

4

2

0

BH2-O2-3Q- 1

............ I" ........... I ............ I ........... -I ........... "11

I I I I I

I I I I I

I I I I I

........... Ii ........... I ............ I ........... J ........... J

I I I I

I I I I

I I I I

I I I I

i I I i

_I _'-: --/_--------" , , ,I I I I

............ L .............. i ........... j ........... j

i i I I

I I I I I

I I I I I

I I I I I

....... ----------I------ ........ I ....... ------I ..... - ..... -4- .......... 4

I I I I I

I I I I I

I I I I I

I I I I I

............ ,': .......... ,............ ,............ i ........... ;I I I I

I I I I I

I I I I I

.......... k .... = ...... I ....... -- .... I..... -- ..... .=4-- ......... --4

I I I I I

I I I I I

I I I I I

I I I I I

...... I........... --I ........... '1

•'/ i .i .' .' .'I I l I I

I I I I I

, , , I , , , I , , , I , , , I , , , I

0 2000 4000 6000 8000 10000


Figure B.6 Typical 90 ° Tension Test Strain Data for 2-D Braided Material LLL.

B.4

3O

25

2O

lO

5

0

BH2-O3-3Q-1

I

I

I!

I

!

!

!

I

!!

I

I

I

!

I

I

!

I

!

!

!

I

!

I

I

!!

!

I

........................................................ I

!

!

!

I=

, . , i , , , I , , , i

0 2000 4000 6000


Figure B.7 Typical 90 ° Tension Test Strain Data for 2-D Braided Material LLS.

25

2O

.-'=" 15_9

C/)

co 1o

BH2-O4-3Q-1

I I, , I

• iI I

I II I

I I

I I

- -J ......... ! .... L..-

,l

2000 4000 6000 8000 10000 12000 14000 16000


Figure B.8 Typical 90 ° Tension Test Strain Data for 2-D Braided Material LSS.

B.5

(/)L_.U)(/)

8O

70

60

5O

40

3O

2O

10

0

-2000

r ...... _ ...... rI

I

I

L f

t

| I

i J

I t

_---_--I I

i !

I !

L .... J-t !

m !

: iD- ..... I"| t"

n u:

_. ...... L

I

I

i I I !

BH2-O1-5L-2

...... T ....... , ....... r ...... _ ....... r ...... "_I I , , I ' '

, , I I I I '

I ' I , I

L I ....... o....... L ...... _ ...... L ...... J

, , , .- , _,_ , ,I I ' J J_ " ' ' '

I I I I I I ', , _/, / : ', , ,I. J. .... L. _I._. ..... L ...... J ....... L ...... J

....... , ...... , I I , I, , /f, : ', , ,I I , I I ' I, ,// ', ,, : , ,

....... '- ...... _ -I .... '...... I. ..... -, ....... _- ...... -,, , ' I ' I '

, / Lf ', °' " ' '

, "_rl I ,I I , ..... / , ....... I ...... I....... ,--- _'/__- r --, r -,I ' I ' ' ' ',// ', : 1, ' ,,'// ' ! ! I .... AxialGage1 I"_/-'--': ....... ',....... rl I,, , I ' " I._, : : ',1........ Ax_Ga_2 I,

-,-f- { I'...................... - ....... Transverse Gage

I ' , I,r : : ,, ',1 I,, , , I , , , I , , , I , , , ! , , , I , , , I , , , I

2000 4000 6000 8000 10000 12000 14000

Figure B.9.a


Typical IITRI Compression Test Strain Data for 2-D Braided Material SLL,

(1/8" Thick, 1." Long).

U:l

(D

8O

70

60

5O

40

30

20

10

0

BH2_l-5M-2

-I" ...... T ....... , ....... r ...... -* ....... r ...... -i

I

I

I

I

I

I

Axial Gage 1

,A}_I Gage 2

Transverse Gage

-2000 0 2000 4000 6000 8000 10000 12000 14000

Figure B.9.b


Typical IITRI Compression Test Strain Data for 2-D Braided Material SLL,

(1/4" Thick, 1.5" Long).

B.6

BH2_1-5G-3

90 rI

I

I I

80 r-_--l 1I, _

......60 ,.-L .......

I I

* t! I

50 [--_.......I t

I !

40 _--. _ -I I

I

,30 _ ......' |!

, LA_

ZO _ .... _ .....

' tI

!

lO ,_.....I

I

0

r .......................................- , r -, r

i i i

i i

i

IJ')* II I

I I

I

! I

! !

iI I

I

I

I

J.

I I !

! ! I

! ! I

I I i

I I I I

I I I I

I I I I I

I I I I I

I I I I

I I I I

I I I I

I I J

I I I

I I I

I I I

I I I

I I I

I I I

I I I

I I I

.... li

.... Ii=!

-2000 0 2000 4000 6000 8000 10000 12000 14000


Figure B.9.c Typical Short Block Compression Test Strain Data for 2-D Braided

Material SLL, (1/4" Thick, 1.5" Long).

in

.x.C/)

O9

6O

BH2_2-5L-2

I" .... " .... r

i I

! - iti !

i

50 , ...... _--,I I&t II I

I • I

|

_^ , P4U : ......... ,'k ......................

I

I I % I

I I % I

I I % I

I I t30 .......... " ........ ........ 'I I I

%I I I i

I I% II

I I

I I l%

20 _ ......... _ ..... ,--I I •

I I

t t! !

I I III I

10 *- ......... L .......I I I

I I I

I I

! I

I I

I I I I

I I I I

I I I I

I I I I

, , _ _"| !

I !

m !

l

I I

I I

I I

I I

I I

........ I......... -I

I I

I I

I I

I I

I I

---I .......... I......... -4

I I I

I I I

I I I

I I I

. I I I................ I .......... I ......... -I

' r I'/ : Axial Gage 1 :I I

. __' ....... -AxialGage 2 J

,; ........ Transverse Gage ::

I I

-4000 -2000 0 2000 4000 6000 8000

Figure B.10.a


Typical IITRI Compression Test Strain Data for 2-D Braided Material

LLS, (1/8" Thick, 1." Long).

B.7

U)U)

O3

BH2_2-5M-2

45 tI

I

!,t0 r

! t I

I35 _ ....... _-_ ........

! I

30 _ .........| I t

J j_

| | •

I I t

I I I

| | t

| ! I

i I t

I ! t.&...lb ="......... _ ....

I I •

| | t!! I

10 ,- ......... _ ...... •I I t

I I

_) I,. ......... I. ......

i II I

I I

t I I I

ql I I I

i

I

I

I

II

I

I

I

I

J

I

II

I

I

I

I

:] [i ,AxiN Gage 1 ',I

L .... .. -J

= ,Axial Gage 2 ;I

' i...... _ ........ Transverse GageI

I ,L I

I

I

I

t

I I

I I

-I-

I I

J !

I I

I I

t I

I I

I

I

I

-4000 -2000 0 2000 4000 6000 8000

Figure B.10.b



LLS, (1/4" Thick, 1.5" Long).

O_

7O

6O

5O

BH2-02-5G- 1

I I I I I I I

I I I I I I I

t I I I I I I

! ' , , ,................. ,4 ........ I- ....... '4 .......... •

t I I I I

I_ I I I I I I

I l I I I I I II I I I I I I

=__,,..... ; .................................., , ,,-....... ,I t I I I

I

I

II • I

4rl L. .... • . -J .......I L I

I • I

I L I

I I I

_ , ,,r ....... t'l .......

I •

I I t

20 ' '2r ....... -i I," .....

I I %I I

Io ' \....... ,4 ......l I

l I

I I

| I

I I I

I I I I

J ........ I- .... J ........ I_ .......I I I I

I I I I

I I I

I I I

I I I

1 .... "1 ("

! D ! !

r # t t

I I I I

, 'i.... r'------

I

I

!

I !

I ........ ,""-I !

I I

I !

Axial Gage 1

Axial Gage 2


-4000 -2000 0 2000 4000 6000 8000 10000

Figure B.10.c


Typical Short Block Compre'ssion Test Strain Data for 2-D Braided

Material LLS, (1/4" Thick, 1.5" Long).

B.8

60

50

"_ 40

_ 3o

20

10

Figure B.11.a

BH24)3-SL-2

7O........... mr ........... I- ........... j- ........... i- ........... i

I I I I

I I I I

I I I I

• I I I I

........ _ ............. I-- ........... I-- .......... --_ I-- ....... i_ _- --I

I ' I I _ I d I

• ' I I i I, . , , / ,/ ,........ t .............. L_........... L. - - _ ...... _ ........... ,

• _ , , , I"I _, ,I . , ' / /" ' ', • , ,/ J , ,I • ' jr. f ' ,

........ _ .............. L ......... J.I__. _......... I_........... J" . l I _ I I,. , f 11" ,' . , _ _ , ,

, _ I, , ,.......... '-"......... ' ..,_----_-_L ......... 'J 1 " I I I _ i 1 1 J l i_ -- i -- _ ........... F ...........

I I . | I l

l I I,/ / II l

' ' i 'I = I I

r .......... _ ............... I ..... Axial Gage 1, _ / .,,,r ; I" : / ,'" '! ', I ....... _,_e2

........... ,- _---_ .... '- ........... '--I' 'f z : .' I .......: .",/ ,-" i i I ........ Traosve,_eGage

0 I ...... I , , , I , , , I , , , I

-2000 0 2000 4000 6000 8000


Typical IITRI Compression Test Strain Data for 2-12) Braided Material

LLL, (1/8" Thick, 1." Long).

50

45

4O

35

.-'=" 30

_ 25

_ 20

15

10

5

0

Figure B.11.b

BH2-O3-5M-2

[.................,._I......................E......................iI • ........... I ........... I ....... I ........... I_ I _' , :I ' , _/ ; ,I- .................... _.. ........... I- ......... I- ........... I, r --I , ,7"/ ........ : ,' _ :I , ,_" , ,

, ....... -_----1-........... ,-......... -/#'-.......... ;-........... ',I I I I I I, , _1 , I/: ', ,

' _1. 'I I I I I I

t I I I I I

k" ........ -_ ............ I- ............................ I

' '} Z- i '1 I I I I I

/ ......... __ --- I l I I

i i ........ ": .......... '- ........... ," ........... ,I _ I I I

I I I I I

I. ......... I ..................... l: ',_ -7"-F........... ,"-I Axial Gage 1 r:.... -/ ....- ......... "-I ..... _ F'I" .......... I............ p ........... r- - I

, ,: xlal Gage 2 ,

' "-/ ' '1 tI I" " ....... I ........... I - I

........... _. "- II l_ ........ Transverse Gage :

! ...... I , , , I , , , I , , , I

-2000 0 2000 4000 6000 8000



LLL, (1/4" Thick, 1.5" Long).

B.9

01(f)

.i.-,o')

45

40

35

30

25

2O

15

10

5

BH2_3-5G-3

I I I III | ! !|

B...--.m--...,.l_ ,. D. i......, n. _p.......---- ..- -_---- _--- -_m-_-- II I I I

I h ! ! !

............ P ............... P .............. P _"S" ........... ir

ir ............ "I ................ P ............ I

, ," , _J , ,, I: ' fl - ' '

, '-_ ...... ,,............ ,I

, __"7".'"-'"......,,"..........i

,' I .,_" ', _ AxialGage 1 /"

, _" "_ ..... F ...... -- .... Axial Gage 2 ri

c' _[:i-'-,''-[_i _raT:tinsv e

;" - - - G- , ........ Transverse Gage ,I

I

! | I

-2000 0 2000 4000 6000

Figure B.11.c


Typical Short Block Compression Test Strain Data for 2-D Braided

Material LLL, (1/4" Thick, 1.5" Long).

50

45

4O

35

•---" 30Gr)

(n 25Or)

09 20

15

10

BH2-04-5L-1

..... ".....F..... '..... ]-.... i .....II

I

I

..... ,,---,_- -,,-..... ,'-. _l • l l

..... ,"'" _,. ,:..... L...... _..._.._,...

I I I

i i _i i

I I • I

i s k

..... it" ..... I1'' ..... i- I"

l I I IIl I !

..... L ..... L ..... I.. _I-I i i

I I I

..... f ..... r ..... I---

I

!

I

J .....

!

I

I

i

I

/ .....I

II

4

I

I

I

I

I-

': iI

I

....... ---r ..... r ..... iII I

I I I

I

I I

I I

II I

I I I

I i I

.... r ..... r ..... i

I l I I

I I I I

..... I. ..... L ..... iI I I l

I I I I

I I I I

I I l l

I I l i

--- ....... r ..... r ..... iI I I

! I !

'. Axial Gage 1

Axial Gage 2


-12000 -9000 -6000 -3000 0 3000 6000 9000 12000 15000 18000

Figure B.12.a



LSS, (1/8" Thick, 1." Long).

B.10

(I)

45 _..... ,-..... ,-.....,.....I I I I

I "

l _ ', l ,I I

40 r .... _- r ..... r ..... , .....

I _1 I I

I 1_ I I

I I-- • I I35 e. ................., F "_" ,_ :I I tA I I

I I I, l l

30 b ..... _ .... _. ..... ,.....I I I_ I

I I I I

, , , % ,25 _...... _ ..... _._...,._

I I I _, l

I I I I I

I I I I I

20 b ..... ,- ..... ,..... _.,...I I I qll

I I I _l

I I I ilk

15 ,r..... ' ..... ' ..... i""-I I "_

I I

10 L .L ' I,......... I. ..... I .....

I I I I

l I I I

I I I I II

5 L ..... I. ..... i. ..... I .... i.

I I I I t

I I I I

I I I I

0

BH2_4-5M-1

.... 1 ..... "1 ..... T ..... r ..... r ..... I

I I i I I I

I I i • I I

I I I I I

.... 'I ..... _ ..... T .... r ..... I

I I I I I I

I I I I I I

I I I I I I

I I I I I

I I I I I I

I I I I I I

--I----'l--------- * @'''" " I" -- ---- -- -- IP---- -- -- -I

I I I I I I

I I I I I

I I I I I

"4 ..... 4, ..... I- ..... I'--I--I

I I I I I

I I I I I I

I I I I I I

----4--- .I- .... @ ..... I----i-I------I

I / I I I

I I I I I

I I I I

I t il

' Axial Gage 1 'I I

...... ,!

"_ - -Axial Gage 2 'I I I

I I

" - "_ _ ........ Transverse Gage! I

I I

-12000 -9000 -6000 -3000 0 3000 6000 9000 12000 15000 18000


Figure B.12.b Typical IITRI Compression Test Strain Data for 2-D Braided Material

LSS, (1/4" Thick, 1.5" Long).

5O

45

40

35

30

25

20

15

10

5

0

,--------,--...,.....,.....

I I I

I I I

, _-- -,-........... ,.....I • I I

........... I .....I. _ %_I

I I • I I

I I • I I

r ..... r - - - _-r ..... ,.....I I %1 I

I I _ I

L ..... L ..... !IS .... , .....I I I

I I I _I I

I I I t I

..... _ ..... _ I I_ i _l I

I I I _ I

I I I Iii II I / I

r ..... /" ......... _" t-u-

I I I qll

L ..... L ..... L ..... I_ -- --

I I I I I

l I I I

I I I I

r ..... r ..... I- ..... I- " -

t

I

..................... %_-

BH2_4-5G-1

i... ... ....... T ...... r "''" p .... - I

! I I I

I I I I

.... I I

I |

I I I

......... a ..... A .... L ..... I

I I I I

I I I I I

I I I I

.... 1 ..... '1 ....... r ..... r ..... ,I I I I !

I I I I I

.... J ..... J- A ..... L ..... L ..... II

I

I

--I ....

I

I

I

"1""

I I

I I

JI -- I J I 1I!

' 't! I

"-J ..... i-

I I I I

I I I I

I I I

I I I

I I I

..... _ ..... r ..... r ....

I I I

I I I

,Axial Gage 1

-Axial Gage 2


I

I

I

-I

I

I

I

"1

I

I

I

-12000 -9000 -6000 -3000 0 3000 6000


Figure B.]2.c Typical Short Block Compression Test

Material LSS, (1/4" Thick, ].5" Long).

9000 12000 15000 18000

Strain Data for 2-D Braided

B.11

b_

45

4O

35

3O

25

20

15

10

5

0

BH2-01-5W-1

.................... r ......... r ......... r ......... r .........| I I I

| I I I

II I I

• ----------------- ----- .... I1" ........ -r ....... -Wlp ...... ---IP-* ..... -

I I I I

I I I I

I I I

I I I I

I I I I

I I I I

......._......--.----..,.........,........., .......r.........

i i I

I I I I

I I I I

....-....- ..-...-..-,.........,... ....,.....-...,.........

J I .P .P

I i I

I I I

I I I I I

I I I I I

I I I I I

.......... l ................. [ l -- ! ...... If ........ [ ..... i . . -- I

I I I I I

I I i I I I

I I I I I I

I I I I I I

I I I I I

I I I I I I

........ L----. ...... L ......... L ......... L ...... .----L ..... .------I

I I I I I I

I I I I I I

I I I I I I

, I , I , I , I , I , I

0 1000 2000 3000 4000 5000 6000


Figure B.13 Typical IITRI 90 ° Compression Strain Data for 2-D Braided Material SLL.

,,¢,

U3

3O

25

2O

15

10

BH2-O2-5W-1

...... " ................. I ............ I ...... " ................ "1

I I II I I

I II

I I

I I I

I I I I

I I I I

I I I

I I I I

I I i I

I I I I

I I I I

I I I

I I I I

I I I I

I I I I I

I I I I I

I I I I I

I I I I

I I I I I

I I I I I

I I I I I

I I I I I

I I I I I

I I I I

I I I I l

I I I I I

I I 1 I I

I I I I I

, , , i , , , I , , , I , , , I , , , I

0 2000 4000 6000 8000 10000


Figure B.14 Typical IITRI 90 ° Compression Strain Data for 2-D Braided Material LLL.

B.12

35

3O

25

"_ 2O

U')

t.,t)

_ 15u)

10

BH2-O3-5W-1

.......... r ......... r ......... r ......... r ...................

I I I I

I I III I_

I I I

I I I I

.......... I- ......... I- ......... I- ........ I- ..................

I l I I

I I I I

I I I I

I I I I

.......... L ......... L ......... IL ........ L ..................

I I I I

I I I

I I I I

I I I I

.......... L ......... L .....................

I I I I

I I I I

I I I I

I I I l

I I I

.......... r ........ , ......... r ......... r ......... i" .........I I I I I

I I I I I

I I I I I

I I I I I

.......... r ........ r .......................................

' :I I

! !

....... _-......... _ ....................................I !

I !

, I , I , I , I , I , I

0 1000 2000 3000 4000 5000 6000


Figure B.15 Typical IITRI 90 ° Compression Strain Data for 2-D Braided Material LLS.

,,e

rE)

¢J3

09

45

4O

35

3O

25

2O

15

10

5

0

0

I

I

I

I

I

I

I

I

I

-r

i

I

I

I

I

I

BH2-O4-5W- 1

- r ..... i- ..... I- ..... i ...... i ...... h-

I I I I I I

I I I I I I

I I I I I I

..... r ..... _ ..... I ...... I ...... I-

I I I I I

I I I I I

I I I I I

..... r ..... _ ..... i ...... i ...... I-

I I I I I

I I I I

I I I I

..... r ..... I- ..... I ...... I-

I I I I I

I I I I

I I I I I

--I ...... I--

I I

I I I I

I I I I I

I I I I

I I I I

I I I I

-I- ..... I- .... I ...... I ...... I-

I I I I I

I I I I I

I I I I I

I I I I I I

I I I I I

l I I I l

..... t. ..... I. ..... I ...... I ...... I-

I I I I I I

I I I I I I

I I I I I I

.... _ ..... _ ..... -3 .....

I I

I I

I I I

I I

I I

I I

I I

I i

I I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

.... J ..... J

I

I

I

I

I

I

I

I

I

I

I

I

.... '=4 ..... 4

I I

I I

I |

I I

I I

I I

.... _ ..... J

I I

I I

I I

2000 4000 6000 8000 10000 12000 14000 16000 18000 20000


Figure B.16 Typical IITRI 90 ° Compression Strain Data for 2-D Braided Material LSS.

B.13

70 r ..... r ....I I

I I

I I I

,_,. ,_n__ __-,.....

i '!!Rt_ _ . _k ....v_

BH2-11-3A-1

l I

I I

-I- ..... I-

I I

I I

I I

I I

_ eL ..... I--

I

I

I

I

.......... I_

I

I

I

I

I

I

I

I

..... i .... Ii_ ,I

---I-

| I

I !

I I

I I

..... i" ..... i ...... I ...... I ..... --I ..... "l ..... "l ..... "1

I I I I I i I I

I i I I I I I

I I I I l

I I I I

I .... I .... _ -- I i i I _

I I I i

I I I I I

I I I I t I

I I 1% II I.....,......,...... .....I I ', \I II I

I | I I I II

I I I _ II

..... i .... J ..... J ..... J .....

O I I I I s

I I I II

I I I I I I

I I I II I

I I _ /! !

I I I I I

I I II l I

I I I I I I

"" ...... i- ExtensometerI

' ' Axial GageI I

--I ..... I-- "1

' ' ........ Transverse GageI I

I I

_ II

-4000 -2000 0 2000 4000 6000 8000 10000 12000 14000 16000


Figure B.17 Typical Tension Test Strain Data for Stitched Uniweave Material SU-1.

O'}

CO

oO0

Figure B.18

BH2-12-3A-1

70 r ..... r .......... r ..... I ...... I ...... I ..... If ..... _ ..... _ .....

I I l I I I _ I I I

I I I I I I _ I I II

I | I I I I I I

60 ' ' ' ' ' ' ' ' ' '!,..... F..... : : : : : :.1" : :I _l. l I I I I I _ _ I

, % , , , , _ l j_r'l , I

5O L. _ . .I.. .......... L ..... I ...... I ...... _ ..... _---- --J ......... _ ..... J

' _ ' ' ' ' ' ' ' 'i 'l, - , , , , ,, % , , , , _ _,_ , , ,I I I I I I _P" / I / I I I

40 ,. \ _. ,- , ---' ...... '---_---' ..... -'..... -'..... 'I .... I ......... I ..... I''" _ Ij_/ /I I I I I, .., , , , _'/,:__----' I

i I _ i I I _....L

, % , , , .,_" -'i-- -- "-,-- , , ,

30 r ..... ,x......... F ..... ,.... -_ .... ,..... -,..... -' ..... -' ..... ;I I _I I I _I II III III I I, ,, , , i', , ,I _ ql I i / i I I I i I

i I • i I/ I I I II

20 r ..... r-. ........ r .... _ ..... ,..... !-'1 Extensometer I_I I I I I _ I II I _ I I I I • I

10 ' ' _ Il I _ I I l I, , %-_" __7"1 ........ Transverse Gage I'

I I I I I I, , _/ : : : ':[ : : _,0 I,,, I ...... I,,,I,,,I,,,I,,,I,,,I,,,I,,,I

-4000 -2000 0 2000 4000 6000 8000 10000 12000 14000 16000


Typical Tension Test Strain Data for Stitched Uniweave Material SU-2.

B.14

BH2-13-3A-1

7O

6O

50

4O

30

..... i i r i ;..................... i10

0

-4000 -2000 0 2000 4000 6000 8000 10000 12000 14000 16000



7O

6O

5O

"N 4O

(/3

(t3

3003

2O

10

0

-4000

BH2-14-3A-1

t ..... f" - -i" ..... i ...... I ...... J ..... "1 ..... "l ..... "l ..... "i

| | a I I I I I I i

I i a i i i i | I l

i I l I l I I i I I

i I I I I I I I D

IN4 .... I'= .... _ ..... I-= ..... I ...... I ...... I ..... =,1 ..... -- =,l -- ._='4-- --_'.1 ..... 4I I I

I I I I I _ I II _li I • I I I I I

I 11 I . l I I I I I I I

=..= =I,= ........... i. ..... i= ..... i.=..==l ..... ,,4 .... d..w==.=l..===J

I L I . I I I I I ! I

I • f • I I i I I I I II L I . I I I I i _ ..... I

I L -- I . I I I I,_P /I I /I I I

I I = I I I I I I I

, _, . , , , //q : : , ,l _ l I I _ I I I I I

I I " I I I I I I I I, a - , , _ .... :..... -..... -___ , ,i" ..... ," .......... F ..... ,.... ,...... ,..... "3..... "5..... ; ..... ",, , _ - , , j', --:- .... -, ..... --:- - - , ,I f " I I I I I I I l. ,_ . , ,,j" : : : : , ,' '\- ' I',,...... ,,..- -- ..... ,,-- ometer

I I " I I I 1 I '

iF" ..... P'- ............. I ...... I ..... _1--- I'l

" : " ' ' ' ' I\. ....... Transve.e,i

i

I I --- l l I l I

, , _/ : ', : : I . . . I,I,,,I ...... I,,,I,,,I,,,I,,,I,,, I,,, I,,, I

-2000 0 2000 4000 6000 8000 10000 12000 14000 16000


Figure B.20 Typical TensionTestStrainData for Stitched UniweaveMaterialSU-4.

B.15

BH2-15-3A-1

........................ i..........i.....iI I !

I l l I l i I

60 ,. -. __. ..... ,...... ,.... ,.. - .4..... -, ..... -4.....I - I I I I I I I I

I I I I I I I I I I

, % , _ , , , , , /, , ,

,. , _ , , , , ._:/_, , ,50 L-_.--,- ........._ '-..... '...... '...... '..... _'J.... "J..... "J..... J

I I I I I I I ...., --I-- __

I _l_ I I I I I I I I

I • I J I I I I _I I I I l

' I ' J l l ' l _! ' ' '

L j I.. JL IL ..... | .... I ...... i_r_ _ _ .,I ..... J ..... J ..... J,'-- C, ......... , ,'" ' ' ' ' '40- , , _I , , ,/r _ , , ,_ , _, , , , , , ,

_0 ' iL "1 , , ..'_I__.... a..... J ...... , , i30 r ..... ,",.... -r ..... ," ..... ,..... _ ..... ,- -- -- ", ..... -, ..... " ..... "

I f _ I I I I I I I I

l I II I I I I I I I20 ' ' \ .-I I"r ..... r - II " - "1" ..... r .... _1- _ H£. ..... !- -I Extensometer I"I I I I I I I, , _ :1 , /', ', :1 I,' ' 't 1 , jS" , , ! I ..... Axial Gage I iI- ..... I- ............ I ...... I ...... I- - .4

I I _l I I I I I10 ..... _ ....... Transverse Gage i

I I I I I I I

0

-4000 -2000 0 2000 4000 6000 8000 10000 12000 14000 16000



...,¢¢d}

.¢..=,

cO

120

100

8O

6O

4O

2O

Figure B.22

BH24)5-3A-1

............. ,....... r ...... "1....... ,............. 1 ....... ,I I ' I I

I I I I I

I I I I I

I I I I I

I I I II

'I-

F'--':' ...... ,;...... :.,............_ u._...... T, ,'

_, , , ,I I I I I l i

I I I _ l I I

p -- -- -- -- -- " ....... I" ...... P ...... "1 ....... I ..... r ...... 'I ....... I

I I I I I I I '

I I I I I I

I I __ii i_.=_ IIL II I IF, I I I

I I I I I I ' I

I I I I I I I I

I I I I I I I

I I ' I I ! I I

I I I I I I I I

, I I I I I l i

IIIN ............. III......./_ ii:]IIN ..... .4 ....... , ....... IN ...... Extensometer'4....... Ii Ill

I A.'_ I I I / I

I I I I I /I, ,Y'i i i ..... _x,_,_0e:".................. i'......i'......':: I',, , , , , ,,........ Transverse Gage, I I I I I

0 ' 4_... ! -- . I , , , I , , , I , , , I , , , I , , , II I I I I I 1 I ! I I I I I I I I , I I I I I

-2000 0 2000 4000 6000 8000 10000 12000 14000


Typical Tension Test Strain Data for 3-D Woven Material TS-1.

B.16

120 r .......I

I

I

I

I

100 r ......I

I

I

I

80 ,_

_ ',I

_ 60 _-

_ ',I

40 r ......!

!

!

I

20 _I

!

!

01,,,

-2000

BH24)6-3A-1

I

.......i.......i...........,,, -I I I

....... ,...... _ ...... -: .....I I I

I I I

! I I

' ' i, , , I , , , I ...... i

0 2000 4000 6000 8000 10000 12000 14000

....... 0....... r ...... "1 ....... i ....... r ...... 1 ....... i

i i i I i i i

i i i i i I i

i i i i i i i

i i i i i i i

i i i i i I i

- --&- .... -I ...... I" ...... .1 ....... o....... r" ........... - ".7"_- " "--' I

I I I I I I

I I I I I

/.,, , ,," , , , ,I I I I I I

..... I.......... .1 ...... "1 _ .... r ...... "! ....... I

I I I I I

I I I I I I

I I I I I I

I I I I I

I I I I I I

--I ..... I ..... 4 ..... I ....... I- ...... 4 .......

I / I I I

I I I I I

I I I I

I I

I I

...... I- ...... .4 .......

t'Extensometer i,

Axial Gage i

........ Transverse Gage II

!

, , , I , , , I , , , I


Figure B.23 Typical Tension Test Strain Data for 3-D Woven Material TS-2.

(/)

(,'3

cO

120

100 .....

80 .....

60

40

2O

0 I , , ,

-2000

BH2_)7-3A-1

............. I....... r ...... "1 ....... , ....... r ...... 1 ....... I

I I I I I I I

I I I I I l I

I I I I I I I

I I I I I l I

i i i i ii i

...... I....... l" ...... "! ....... I ....... I" ...... I ....... I

I I I I I / i i

FI I I I I I

# I I I I I I

I I I I I I I I

-- -- _1 ..... I....... i" ...... .1 ....... I ..... I" ...... .1 ....... II

I I I I I I

I I I I _11_ II I If I I I I I

..... /: : , ,f I I I I I

, , 17"--2-; _ _-_- , ,

I I I I I I I

I I I I I I I

....... 1 ....... I- ..... .41 ....... II ....... ...... I- ...... 4 ....... II

ExtensometerI I I I I

I ! I I I

.................... - ....... Axial GageI I I I

I I I I I

I I I I I/ i i i i---..I I I l - = = • = = = _ -- - - I

, , , t , , , I , , , I , , , I , , , I , , , I , , , I

0 2000 4000 6000 8000 10000 12000 14000


Figure B.24 Typical Tension Test Strain Data for 3-D Woven Material OS-1.

B.17

BH2-O8-3A-1

120 r ............. ,....... r ...... "1....... ,....... r ...... 1 ....... ,I I I I I I I I

I I I I I I I I

I I I I I I I I

I I I I I I I I

I I , , , , , ,I00

f--

I I I I I I I I

I I I l I I I I

I I I I I I I I

I I I I I I I I

80 ' ' ' ' ' ' ' 'r -- -- I i i i ....... I ....... _ " i I -- -- -- _ -- -- i I " " -- I .... I I -- r ...... _ -- I I I I -- -- I

I I I I I I I I

I I I I I I I I

I I I I I I I

I I I I I I

I I I I I

(I) S t "

I I I I I II I I I

G'_ I I I II

, , , J/ ' , , :40 . ............ ,....... _,_.... 4 ....... ,....... _ ...... 4 ....... ,

, , , _ i "_--_-- ,

,' ,, _ : _ Ex_om_t_ ',I I I I,' , , , ..... i,

,"............/,,---7,'.....,i......i,'....... _.......T ao ve -e":'I

I I I I I

I I I I I

0 I ...... I , . , I , , , I , , , I , , , I , , , I , , , I

-2000 0 2000 4000 6000 8000 10000 12000 14000


Figure B.25 Typical Tension Test Strain Data for 3-D Woven Material OS-2.

BH2_9-3A-1

120 r ............. ,....... r ...... 1 ....... ,....... r ...... 1 ....... ,I I I I I I I I

I I I I I I I I

I I I I I I I I

II I I I I I I

I I IlOO _- , f "ll I I , I........ " .............. "" ....... I....... f'''''--1 ....... I

80 i , , , , J__ __, __.,.......-J.I

I

s I I I I I I I

._ I I I I I I II

...... I....... I- ...... .4 ..... I....... I- ...... -I ....... I

_--- I I I I I I I

I I I I I II

I I l l l I II

I I I I I I I I I

I I I l I I II

40 _............. ,....... _ .... _....... ,.............. _....... ,I I I ..... I

, ometer '

" E _' ' ' ...... 'i ..... Ax'_alGa 'I I I I I ' I

i ge ,i20 ,,-............I I I I

I 1 I i I I I,,' ! ........TI

l 1 l l l , lI J I I I I . - I

0 I ...... I , , , I , , , J I l , I ' ' l I ' I ' I l I ' J

60

-2000 0 2000 4000 6000 8000 10000 12000 14000


Figure B.26 Typical Tension Test Strain Data for 3-D Woven Material LS-1.

B.18

120

100

I

I

80 r ......!

I

] 'i

!

60 ,,.......

,!!

!

4o ,. ......I

I

I

I

20 ,,- ......!

I

!

I

0 I , , ,

BH2-10-3A-1

r ............. i ....... r ...... "! ....... =....... r ...... "! ....... oi I I i l I | I

l I I I l I l I

l l O I I i l !

l I I I I ! O I

l I l l I I | I

pi i w=== i..o= ..... l "''= p === w = " "l = = "" "====I " = = " = P = " " = -- = _ = " e " = = =1

I I I I I I I I

I I I I | I I I

l I I I i I O I

I I I I I I I

l I I l I l I

...... I l ....... _ I _ .... _ I I ..... I I ...... _ I I .... _ I I I .... I

I I I I I l l

I I I I I I I

I I l I¢ • I I

'I¢ I I I _'_ m, q I I

k- ...... I ....... I- ...... .4 -- _f_'_ -- - --I ....... I- ...... 4 ....... I

I , , ,_ , ' ' 'I i i iJ$'-- i i ' i

I I I I I I I

I I I I I I I

I I l I l l I

iiiii I........................... I ....... I- .... 4 ....... I--

I I I I

i ' -- --, ExtensometerI I I I

I I I I

' ' ' ' ....... ti............ I- ...... 4 ....... I

I I I

Ill ,I' 1" ," ........ Transverse Gage /+I . - II

, . , I , . , I , . . I . , , I , , , I , . . I , . , I

-2000 0 2000 4000 6000 8000 10000 12000 14000


Figure B.27 Typical Tension Test Strain Data for 3-D Woven Material LS-2.

"3

¢,o

cO

6O

5O

4O

3O

2O

10

BH2-11-5G-1

--I ......... "_ ......... --I .........

I I

I I

I

I

I

--'!---------- ....

I

j' o!

! !

! !

! !

! !

0 e

I--

I I I

I I I

I I I

I I I

I I I

I I I

I I I

, , i jI I I

I I

I I

!

!

!

!

!

!

!

!

I ' I I I

I ] I I i

! !

j i i.......... I .......... I .........

--_= i i IJ , i ,

I lI

I I I I

! I l l

I

, J , ,

......... I------., d- ----I ......... "4 ......... -4 .........

, / , i ii_ I I I

/ I I I

/ I I I.......... I ......... ,,4 ......... =4 .........

I

l

,Axial Gage 1

Axial Gage 2

0 2000 4000 6000 8000 10000 12000

Figure B.28


Typical Short Block Compression Test Strain Data for Stitched Uniweave

Material SU-1.

B.19

BH2-12-5G-1

60 .......... r ......... ,.......... , ................... _ .........I I I I I

I I I I I

I I i I I

I i I I I

! i I I I

_V .......... _ ......... ,- ......... ,......... ......... ....., , 1.- J /

I

40

3O

2O

10

0

I II I I I

! I I _ I I

I I I I I I

I I I I I I

/ /I I I I

I I I I I I

I I I I I

I I I I I

I I I I I I

/ /I I I II I I I I I

I I I I I I

I I I I I

I I I I I I

/ /! I I I

I I I i m • I

' ' ' li", , , Axial Gage! I

, , I "" - A×_G_e2, ,-I:I I I

I I I I I II I I I I Ii I i i i I

, , , I , , , I , , , I , , , I , , , I , , , I

0 2000 4000 6000 8000 10000 12000

Figure B.29



Material SU-2.

6O

50

4O

"5

30

u')

2O

10

Figure B.30

BH2-13-5G-I

"¢ T 'i" -i ......... "i ......... "I

I I I I I I

I I I I I I

I I I I I I

II

4 _ 4 ', ',I I I I I

I I I I I

I I I I I I

I I I I I I

I I I I I

I I I I I

I I I I I

=P ......... I=

I I

I I

!

I

I

I I

I I

! II I

!I I I

I I I I

I I I I

I I I I

I I I I

I

I

II

I I

....... I .......... I .........I I

I I

I I

I I

I I

I I

I

Axial Gage 1 t "Axial Gage 2 " ]I

!

I I

i I

0 2000 4000 6000 8000 10000 12000



Material SU-3.

B.20

6O

5O

4O

30

2O

10

Figure B.31

BH2-14-5G-1

I

I

I

I

I

I I

I I

I I

I l

I I

I

I

i

I

I

...... P- ......... I--

! I

!

!

! I

! I

I I i I

.k , ÷ :I I I I

I I

! I I

I I I

I I I

I I I

I I I

I i i

i I i I

I I I I

I I I I

.... i ......... _ ......... _ ......... 4

I | I I

I I I I

I I I I

I I I I

I I I I

...... I- ..... I .......... I ......... -4 ......... -I ......... -I

II I I I I

I I I I . I

, , ,Axial Gage 1 ,I I

.......... I .......... i ..........

, , , ,Axial Gage 2! I I

I I I

I I I I I I

2000 4000 6000 8000 10000 12000



Material SU-4.

6O

5O

4O

o_ 30

u0

2O

10

0

Figure B.32

BH2-15-5G-1

"l ......... "1

! I I I I

I I I I I

I I I I i

.......... P ......... I .......... I ......... "a-- "a ......... "I

I

, , , ,b,/ , ,, , , i>- , ,, , , _/ , i ,

.......... r" ......... ,.......... ,.... IJ"- - - "I ......... "_......... "_, , , // , ,, , ,_y ,, , ,f I I I

, , _r , , ,, , f/, , , ,

.............................! ::.........i..........i.........:,, ,_j_-: ', , ,! ! !

..................',..........',.........i--::-:.........i" I I I ' ,Ax_

i i i I i i

Gage 1'' 'I

........ I- ......... I.......... I ......... _ --_>'_ .....i........ I _-,_x_G_e=,:,I I I I I I

I I I I I I

I I I I I II I I I I I

, , , I , , , I , , , I , , , I , , , I , , , I

2000 4000 6000 8000 10000 12000


Typica] Short Block Compression Test Strain Data for Stitched Uniweave

Material SU-5.

B.21

Figure

90

80

70

60

50

40

30

20

10

0

0

B.33

BH2-O5-5G-1

........ r ........ i i

I i i i I i

I I I I I I

I I I I I I

i.=i.ip==._i=.iilii..i==.nii...i=..==9='--i=i'--i9--=ili'iiI_

I I I I I I

I I I / I II I I I I

lllillllllll II IIIIIII III I _ _'='= =='_

I I I I I I

I I I I I

I I I I I

I I I I I

I I II I I

I I I I I I

| I I I I I

I I I I I!

I I I I I

......... I ......... 4 ......... _ ......... 4

I I I I

I I I I I I

I I I I I I

I I I I I I

| I I I I I

' I..................,......... ,AxN Gage 1 -.,I I

I II

, I L._ageI

-I .......... I ......... ---[.

I I I

I I I I I I

I I I I I I

2000

Typical Short

Material TS-1.

4000 6000 8000 10000 12000


Block Compression Test Strain Data for 3-D Woven

1/1

ffl

9O

8O

7O

6O

5O

4O

3O

2O

10

0

BH2-06-5G-1

........ i "_ ........ "_ ................... r-- ! ...................

I I I I I I

I I I I I I

! I I I I I

.......... I" ......... l .......... l ......... 9 ......... 9 ......... "_I

I I I I I I

I I I I I I

I I I I I I

.......... l- ......... I.......... I......... 9 ......... 9 ......... "I

I I I I I I

I I _1 / I I I

l I /I / I I I

___I I

, , , ' ____, ................... r = ......... i ......... i ......... 9 ......

I I I I

I I i I I I

I I

.... _.__ ................... O- .................. I......... ,.4 ......

I I I I

I I I I I II I

I I I I

I I I i i !

' ' - Ax_ Gage I "i.................. I.......... I......... = =

I I

,' ', ', - - ,Axial Gage 2 / :' I I I ....... / -- I

I I I I I I1,,,i,,,i,,, ,,,, I.,, ,0 2000 4000 6000 8000 10000 12000


Figure B.34 Typical Short Block Compression Test Strain Data for 3-D Woven

Material TS-2.

B.22

9O

8O

7O

6O

U')

_ 50

_ 40

30

20

10

0

0

Figure B.35

BH2_7-5G-1

..... r ......... * .......... I ...... "_ ..............

! I I _ I I

| ! t I I

| ! I / I I

I I I I I I

| | I I I I

I I I I I I

! 1 I I

I I I I

I I I I

i I I I I

I I | I I

I I I I I

I I I I I

I I I I

I I I I

I I I I I

| I I I I

I I I I I

t I ! I I

I I * | I

I:'-- _I

I

I

!

¢

I

' ' I........ ,.......... ,. ,Axial Gage 1

I I

! ! I

, , , ,Axial Gage 2_ _ _ L- .I .......... I .........

| I I

! I I I I

I I I I I

2000 4000 6000 8000 10000 12000

Typical Short

Material OS-1.



9O

8O

7O

6O

5OU')

U)

4O-i,.-,

(.f)

30

20

10

0

0

Figure B.36

BH2_8-5G-1

! I

I I

I |

...... I" ......... e-

l I I

I I I

I I I

I I I I

I I I I

I ! !

....... t- ............ I ......... ,4--- .......

I I I

I I I

I I I I

...... J--- -I .......... I ......... -4 .........

I I I

t- -I .......... I ......... "1 -'---_ ....... "1

I I I I ,/_ l

I I I I I I

I I I I I I

......... I ........... "l ......... "1/I I I I

I I I I I

I I I I I I

......... I .......... I .... "1 ......... "1 ......... "1

I I I I

I I I I

I I I I

...... "1 ......... "1 ......... "1

I l

I I

I l

"I ......... "1

I I

I I

I I

"4 ......... ,4

I I

l I

I I

I I

i I

.,x, olI_iAxNGage2 _i

I I

I I

!

I I I I

' ' II I

I I

I I I

.I. ........ I .......... I .........

I I I

I l I l

I I I I

2000 4000 6000 8000 10000 12000

Typical Short

Material OS-2.



B.23

90

8O

7O

60

3x 5Oin

_ 4o

3O

2O

10

Figure B.37

BH2_9-5G-1

.......... _ ......... i.......... i ......... _ ......... _ .........

l I I I

I I I

, 7, 7, ..... ",.........I I I i

.................... I.... )_ "" ":............ ', ,, ..... ..........I I I I

I I

f t

.................,_.,...../...:..........'.... ,! I !/ , _ : : ,

/ ,/ , , ,

, .t -72_ ....... ,,......... -;..... -:........., / /, , , ,V" / ' ' ' '

i, "2"-":-'" .... ',......... I ..... I .........I I !......e_._:/....'__-- ,.......b........I - AxmJGagel -

" :A I/ Axial Gage 2,,# L I I n,- .- - -/- - - ......... .......... ......... ,i i

._ / . , t II/ , , ' J i

I i i i im i i i i, , , i , , , i , , , t , , , i , , , i , , ,

2OOO

Typical Short

Material LS-1.

4000 6000 8000 10000 12000



90

80

70

6O

._z. 50

U)

40,,.,,o')

30

2O

10

0

0

Figure B.38

BH2-10-5G-1

I I I I I

I I I I I

I I I | I

...... I- .... --- I -I ........... ----- .....

I I I I !! I I I I

I I I I I

I I I I I

I I I I

! ! ! !

I I I I I

I I I I I

| I I I I

I I I I I

I I I I

I I I I

I I II I i I I

I I I I I

I|

,Axial Gage 1

.Axial Gage 2

I

I

'!I

I

I

I

II

I4

I

I

I

4

I

I

I

-4

I

I

I

I

!

2000 4000 6000 8000 10000 12000

Typical Short Block

Material LS-2.


Compression Test Strain Data for 3-D Woven

B.24

Appendix C Boeing Specifications

Copies of two Boeing specifications are included in this appendix for reference. The

first specification, BSS 7260, illustrates the modified ASTM D695 compression fixture

used for the compression interlaminar shear tests described in Section 13.1. The second

specification, BSS 7273, describes the procedure used for the double cantilever beamtests described in Section 14.1.

C.1

1/

General llote z

The inside faces of the assembled fLxtu[e shall ClOlm within _+ 0.00l inch and sh.ll be maintained to• finish of 32 Ra or better Xn accordance v_th MiSZ B 46.1.

1/ OPTION: Relieve interior of bolting tangs 8 minimum of 0.02 inch.

IIODIFZED D6gS CONPRESSION F_XTURE /'OR TYPE IllAND TYPE IV CCO(PRESSION TESTS

rLgute 13

BSS

7260

Page 26

ORIGINAL ISSUE:x-m R|V,

;._-_; REVISED:. "C" 12-23-_8

C2

SCOPE

This standard describes the procedures for Mode I interlaminar fracture toughness

testing of materials by applying a constant tensile crack opening displacement rate

to a constant width and height double cantilever beam test'specimen. The fracturing

surfaces are pulled away from each other without sliding or shearing.

APPLICABLE DOCUMENS_

The current issue of the following references shall be part of this standard to theextent herein indicated.

ASTH E4 Verification of Testing Machines.

BAC 5317 Fiber Reinforced Composite Parts

COBTENTS

Not applicable to this specification.

DEFINITIONS

a. Area Method Interlaminar Fracture Toughness - The total interlaminar fracture

energy combining several initiation and arrest events.

b. Brittle Crack Propagation - A sudden crack propagation with the absorption of

no energy other than that stored elastically in the body.

c. Crack Starter - Nonbondable release sheet material (typically FEP for 250F and

350F curing systems and Kapton coated with a release agent llsted in BAC 5317for materials with higher processing temperatures) inserted between the middle

prepreg plies during layup allowing initiation of interply cracking.

Crack Tip Position - Position from which a crack will begin propagating.

Crack Tip Sharpness - a qualitative measure of the crack tip depth or radius.Crack tip sharpness is a function of the material, where a brittle material

produces a sharp crack tip (shallow tip/small radius] and a ductile materialproduces a less distinct crack tip (greater tlp depth/large radius].

f. Ductile Crack Propagation - Slow crack propagation that is accompanied by

noticeable plastic deformation and requires energy to be supplied from outsidethe body.

d.

e.

ACTIVE PAGES: (1) Rev. B (2) Rev. B (3} Rev. B (4) Bey. B (5) Bev. B (6) Rev. B

ORIGINAL ISSUE: REV.:

ENG _ _ ,

FSC_ NO. S13_S-I_ IIIV,lI

X 502

"B" 10-21-88

GIC INTERLAMINAR FRACTURE TOUGHNESS

FTR_ R- RF.7 NP_I_('_n t'_D_ T_'rq

ROE'J'WOSPECIFICATION SUPPORT STANDARD

BSS7273

I of 6

C.3

5

S.1

DEFZIZTIOSS (Continued)

g. Fiber Bridging - A phenomena where fibers begin to delaminate from both the

top and bOttOm surfaces. Two crack tips are crested which may iacrease theapparent fracture toughness.

h. Znitiation Znterlaminar Fracture Toughness - A measure of the minimum energy

level required to resist crack initiation.

i. Surface Energy Interlaminar Fracture Toughness - A measure of the energy level

associated with a materials resJqtance to delamination and crack propagation.

TEST SPECIMEN REQUIREME_I'S

PANEL PREPARATION

a. A laminate test panel shall be layed up using an even number of prepreg pliesas illustrated in Figure 1. Cured laminate thickness shall be 0.16 + 0.01 inch.

The number of plzes shall be determined from the cured ply thickness--ascalled out in the referenced specification. All plies shall be oriented in _hezero direction.

b. A crack starter ply shall be placed between the middle plies as shown in

Figure 2.

c. Panels shall be bagged and cured in accordance with the applicable process

specification for the material.

Variable

dimensionbased on

number of

specimens

required

±

T

e Trime

• t o13.0 • 2.0

Trim

3.0

13.0,2.0

15.0*2.0

All dimensions in inches

I,-,-,Insort of

FEF or Kaptoncoated with

a release

agent listedin BAC 531?

0 beg.

Fiber

direction

DCB SPECIMEN AND PANEL GEOMETRY AND DIMENSIONS; PLAN VIEW

Figure 1

BSS

7273

Page 2

ORIGINAL ISSUE:S-12-83

REVISED: "B" 10-21-88

C4

5.2

S

S.1

6.2

SPEC IHEN PREPARATION

Nachine specimens to the dilensions as sho_m in Figure 2.

Oo

LOAD (P DETAIL !

TOP ¥11_

LOAD IP) °_14----- t

CONSTANT WIDTH AND HEIGHT DGUBLIt CANTZLEVZR BEAN (IX:B) SFZCI_N

Figure 2

• 0a 1 lqm_r/_.ePMmTuS

TEST NACHINE

Testing shall be perforned vith a constant displacement rate test nachLne. TestmechLne shall be verified Ln accordance vith ASTM R4.

SPZCI_N GRIPS

Triangular specimen grips, as shorn in Figure 3. are attached to the upper and loverbean halves as disFlayed in Figure 4.

IIOT£J A11 dimansioeo in incites /Ill

/ f 1

," ]__rigure 3

BSS

7273Page 3

ORIGINAL ISSUE: 5-12-83 REVISED: "B" 10-21-88

C.5

6.2

7

7.1

SPECIMEN GRIPS (Continued)

CRACK TIP

POSITION

ALl dLmt'nS_Onl An inches

kGRIPS

POSITIONS OF THE TRIANGUALAR SPECIMEN GRIP IN THE DCE SPECIMEN

Figure 4

PROCEDURE

PARAMETERS/MEASUREMENTS

a. A minimum of five specimens shall be tested for each desired temperature.teapersure shall be 75 + 10P.

b. A crosshead speed of 1.0 inch/mln shall be maintained to product a loaddeflection curve.

]Room

c. To measure crack tip position, each crack arrest position shall be marked onthe edge of the specimen during loading with a visible urking pen. k IOxmagnifying glass is recommended to visually observe end "ark t_e crack tipposition. Each crack tip position vail correspond to an individual load llneas shown in Figure S.

**'0"** Be sure to note whether bridging of fibers between u;perCAUTION and lower surfaces occurs. Thl8 phenomena can significantly******* affect the results since sore than one crack tip is _rscturing.

d. The area llIustrated in Figure 5 represents the energy absorbed between twoknown crack length pomltLons.

Ignore first Peak, or mmnualLycrack aOout 0.5 knch. since the

f_p crack starter gzvmS • false

crack tzp sharpness that ts

not a functzon at the natarsa_. Crack Tkp Poo&tkon x

CrossJ_ed OefkectLon ( Sh. )

AREA METHOD LOAD DEFLECTION CURVE AND DATA DETERMINATION

Figure S

BSS

7273

Page 4

ORIGINAL ISSUE:l-NMO lilY.

5-12-83REVI_dEO. °B" ,].0-21-88

C.6

?.2

?.2.1

7.2.2

CALCULATIOK OF SURFACE ENERGY INTERLAHINAR FRACTURE TOUGHNESS

AREA I4ETHOD

• . Are• method GIC interl•nin•r toughness l• calculated from the follovin?foreul•.

At•• Interl•nin•r Toughne•s -

where

E

A

B - specinen vidth (in.)

E (in-lb/in. 2)A x a

• re• of the load deflection curve be tmmen the initial

and final crack positions.

crack length corresponding to E, initial crack tip to final crack tip(in.)

b. To obtain the energy involved in fracture (ln-lb/inl), the area under the curve• t two crack length position• seen in Figure 5 •hall be nea•ured.

c. Ignore 1st peak in calculation, or manually crack about 0.5 inch, since the PEPcrack •tarter gives • false crack tip sharpness that is not • function of thematerial.

d. The area illustrated in Figure $ represents the energy absorbed between two

known crack length positions.

INITIATION M_THOD

Initiation Method

GIC interlaaln•r toughness is calculated from the following fornula:

GIC m

where

p

a •

3PY GIC is in inch-pound/inch2

fracture load measured In pounds at the bott_ of the small savtoothezcursion8 (arrest) or fracture load •t tip of Jawtooth excursion(initiation)

crack length measured visually in inches and recorded manu•lly at itscorresponding load position on the chart (arrest or initiation cracklength)

specimen width in inches (e specimen constant)

calculated crosshe•d deflection in inches corresponding to lo8d value P.

These parameter• are •born in Figure 6.

8SS

?2?3

Page 5

ORIGINAL ISSUE:a m iEv iwmm

5-12-03 REVISED: *E" 10-21-88

C7

7.2.2 INITIATIONMETROD (Continued)

To measure the crosshead deflection Y for the GI_ initiation calculation, it isnecessary to obtain the load-deflection curve or_g_n by deliberately unloading alon9the dashed line as seen in Figure 6.

,wJ

/f

J

/

f/ Crack Length (

Selected at this IPol ; t _on

I R

CROSSHEAD DEFLECTION (in.)

INITIATION MZTNOD LOAD'DEFLECTION CURVE AND DATA POINT DETERMINATION

Figure 6

ItEPOEI'IIIG

Report specimen identification, teat temperature, and GIC to the nearest in-lb/ln 2.

BSS

7273

Page 6

ORIGINAL ISSUE:i-m Ally.

S-12_83REVISED:- • 10-21-88

C8

Form ApprovedREPORT DOCUMENTATION PAGE OMBNo.0704-0188

_ data _ode¢l. and co_q0t_r_ngand r.._. g t_p.oolmct©n¢=_lor .rn&t_n_._end co.n'cnp._s ,eg_udi_Ot_m ou_ est=rrate o__ olher ,t_cec=d Ibis c°l_c_°n o_=nlorrnaton.k'_<E'_g Sugg_lnlOr_tot_ ¢h= iouc0e_,to W_h_gton H_OClUa_I _,rv_. L_eclorate _o¢iraor_.._ _rat_ons and Reports, 1215 J_ierl_=n DavusH_ghway,Surle1204.Arlington,VA 22202-4302, and tothe O(fce, of Mana0_t and BuOy, Pa_e_o,rk Reductcm Prolect Io704-0188), Washm,gton. DC 20503.

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

July 1994 Contractor Report4. TITLEANDSUBTITLE

Test Methods for Textile Composites

6, AUTHOR(S)

Pierre J. Minguet, Mark J. Fedro, and Christian K. Gunther

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

Boeing Defense & Space GroupHelicopters DivisionPhiladelphia, PA 19142

g, SPONSORINGI MONITORINGAGENCYNAME(S)ANDADDRESS(ES)

National Aeronautics and Space AdministrationLangley Research CenterHampton, VA 23681-0001

5. FUNDING NUMBERS

NAS1-19247

WU 510-02-12-09

8. PERFORMING ORGANIZATION

REPORT NUMBER

10. SPONSORING/MONITORINGAGENCY REPORT NUMBER

NASA CR-4609

11. SUPPLEMENTARYNOTES

Langley Technical Monitor: C. C. Poe, Jr.Final Report - Task 7

12a,DISTRIBUTIONI AVAILABILITYSTATEMENT

Unclassified-Unlimited

Subject Category 24

12b. DISTRIBUTION CODE

t3, ABSTRACT (Maximum 2OO word$)

Various test methods commonly used for measuring properties of tape laminate composites were evaluated todetermine their suitability for the testing of textile composites. Three different types of textile composites wereutilized in this investigation: 2-dimensional triaxial braids, stitched unkveave fabric, and 3-dimensional interlockwoven fabric. Four 2-D braid architectures, five stitched laminates, and six 3-D woven architectures were tested.All preforms used AS4 fibers and were resin-transfer-molded with Shell RSL-1895 epoxy resin. Ten categoriesof material properties were investigated: Tension, Open-Hole Tension, Compression, Open-Hole Compression,In-Plane Shear, Filled-Hole Tension, Bolt Bearing, Interlaminar Tension, Interlaminar Shear and InterlaminarFracture Toughness. Different test methods and specimen sizes were considered for each category of test.Strength and stiffness properties obtained with each of these methods are documented in this report for all thematerial systems mentioned above.

14. SUBJECTTERMS

Textile composites; Braiding; Weaving; Stitching; Mechanical testing; Tension;Compression; Shear; Bearing; Fracture toughness

17. SECU RITY CLASSIFICATIONOF REPORT

Unclassified

NSN 7540-01-280-55(X)

18. SECURITY CLASSIFICATIONOF THIS PAGE

Unclassified

19. SECURITY CLASSIFICATIONOF ABSTRACT

15. NUMBER OF PAGES

228

16. PRICE CODE

All20. LIMn'ATION OF ABSTRACT

Standard Form 298 (Rev. 2-89)Preecribe¢li_yA_ISI Std. Z39-t8298-1C_

Date post:	03-Mar-2020
Category:	Documents
Upload:	others
View:	13 times
Download:	1 times

Test Methods for Textile Composites - NASA · Test Methods for Textile Composites Pierre J....

Documents