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Program: Recent Results
Montana State University
July 20-22, 2010
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Thanks
To Sandia/DOE for support since 1989
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Research Group
CoPI Research Engineer: Daniel Samborsky,
Post Doc: Aaron Sears FEA Adhesives
Grad Student: Tiok Agastra Processing, Complex Structure Coupon Testing and FEA
Undergraduate Assistants: Patrick Flahertyand David Buswell
Sandia PIs: Tom Ashwill, Josh Paquette
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Standard laminates re resentin s ars skins
Fatigue Topics
and webs
Adhesive joints
Core/sandwich areas Damage growth at flaws
Ply delamination at details like ply drops and
joints, and near adhesive joints, , , ,
Processing effects
Loading conditions/
Sandwich Panel
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Public Database
at gue ata ase(SNL Website or MSU program
/composites/) Over 190 Materials 11,500+ test results
Updates each March ren s ana yze n pu ca ons
and contractor reports onwebsite; Draft of current
contractor report
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More Detailsontractor reports an pu cat ons onwww.coe.montana.edu/composites/; additional informationincluding resins, adhesives, fabrics, etc.
Contact: [email protected].
on rac or epor an ecen apers on e s e:1. 2010 Sandia Contractor Report (Draft), Mandell, et al.
2. 2010 Sandia Blade Workshop Presentation, Mandell.. , , , ,
Samborsky, paper and presentation, program overview.4. SAMPE 2010, Seattle, paper 398, Agastra and Mandell, Complex StructuredCoupons.
- -. , , , , ,Laminates.6. AIAA SDM 2010, Orlando, paper AIAA-2010-2821, Sears, et al, Adhesives.
7. ACS 2010, Cocoa Beach, Selection of Blade Materials, Mandell, Presentation.
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Presentation Topics
Summary of recent results:
1. Standard laminate fati ue:
fabric and resin effects.. ,
complex structured coupons
-
structures).
. .
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Standard Laminate Fatigue
, = .1. Glass fiber laminates mostsensitive to tensile part offatigue cycles2. Clean failure modesfor materials com arisons
R = Min Stress/Max Stress
Ref. 1
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MSU resin infusion process with hard mold on one side
(panels also supplied by industry)
Ref. 1
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VectorplyELT5500Fabric,FrontandBackViews
a r c , gsm
Ref. 5
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PPG-Devold L1200/G50-E07 (MSU Fabric H, 1261 gsm)
Front ac
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Strain-cycles trends for eight MD laminates, UD fabrics1200-2400 gsm, Hybon 2026 sized strands, filament
, , .
Studies involving systematic fabricvariation with Devold and OCV in progress
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Data Representation
on yc e
Strain Parameter,Power Law Exponent,
- ,Polyester (UP) vs
Epoxy (EP)
MultidirectionalLaminates;TT: Database Laminate
Note: Strains shown onfigures are Initial Strainsfrom extensometer in
[45/0/45/0/45]the first few fatigue
cyclesRef. 1, 5
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Resin Comparison, Same Fabrics
Vinyl esters: intermediatepDCPD (Materia): similar to epoxy
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UP and EP resins with and w/out 90-strands removedin gage section before infusion, UD laminates
Significant effect only for UP resin laminates
epoxy
polyester
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Typical Infused Laminate Property RatiosPolyester (UP) to Epoxy (EP)*
Property Ratio UP/EP
Axial Tensile Modulus (UD) 1.0
.
Axial (UD) Static Tensile Strength 0.90Axial (MD) Static Tensile Strength 0.95
ransverse tat c ens e rac ngStrain
0.42
Axial (UD) 106 Cycle Strain (R = 0.1) 0.51Axial (MD) 106 Cycle Strain (R = 0.1) 0.65
Axial (MD) 106 Cycle Stress (R = 0.1) 0.61
Axial (Biax) 106 Cycle strain (R = 0.1) 0.91
Interlaminar GIc (0-0 interface) 0.55
Interlaminar GIIc (0-0 interface) 0.48
,Threshold Fatigue Strain (R = -1)
.
*Vf = 0.5 to 0.6, UD Fabrics D and H, Biax Fabrics M and P
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Complex Coupons With Ply Drops
Thi kn T rin
Ref. 4
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Delamination TestinMixed Mode Delamination Testing, Different Resins
Ref. 1, 5
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Complex Structured Coupons with Ply
,Purpose: Mini-substructuretest. Sim lified less costl
approach to substructuretesting. Efficient comparisonsof resins, fabrics, geometric
details in structural context..coupons represent morerealistic internal (infused) blade
standard laminate tests
Ref. 1, 4
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Complex Structured Coupon with Ply Drops(See 2009 SDM, AIAA-2009-2411; and 2010 SAMPE paper 398)
Damage
ComponentsAlternate Geometries
Ref. 1, 4
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Damage Growth Curves
Static Fatigue, R = 0.1
Damage Growth with DifferentResins Correlates withInterlaminar G G
Simulation
Ref. 4
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1 PD = 1.3 mmat gue
(R=0.1, Pmax=55.6 kN)a c
2 PD = 2.6 mm
4 PD = 5.2 mm Ref. 1, 4
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THRESHOLDS
-results for three resins:epoxy (EP-1), polyester (UP-1)and pDCPD; R = -1.
Near threshold results (5-mm delamination length L1 in 106 cycles), R = -1,
ResinMax. Force, kN, and thin
side average strain (%)
Force Change
From EpoxyObserved Damage
wo p es roppe a one pos on.
Epoxy EP-1 19 (0.18%) ___ L1, L2, crack at ply ends
Polyester UP-1 14 (0.13%) -26%L1, L2, biax cracking, crack at
ply ends
p . , crac a p y en s
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Blade
Initial Test Parameters
Characterize Nominally Good Quality Joints(Most Contain Significant Porosity)
Range of Uniaxial Loading Conditions (R-values)
ange o rac o e x y I II Failure Modes; Crack initiation and Growth
Strength-lifetime or Fracture Mechanics-da/dN
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Strength-Lifetime Lap Shear Test
es ve - , yc es e , yc es r g(Non-symmetrical Specimen Clamped in Hydraulic Grips)
Ref. 1, 6
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Simulated blade joint study, see AIAA paper AIAA-2009-1510
Joint strength statistics and criticalflaws; failure modes; eometr
Fatigue exponentsPorosity modeling
Ref. 1, 6
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,
Test,
Mixed Mode I and II Cracked Lap Sheares
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Adhesives and GIc from DCB Test
Designation Adhesive Cure temp GIc, J/m2
ADH-1Hexion
ADH-5 Rhino 405 70 938
ADH-6 3M W1100 70 1626
DCB Test
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CLS Adhesive Fracture S ecimens
Ref. 6
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Std. 50 mm 100 mm w/steel
50 mm w/steel G-Calibrations of CLS Specimens
at 4.45 kN Tension LoadStd. 50 mm
50 mmw/steel
100 mmw/steel
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Adhesive Thickness Effect on Mode Mixit
0.80
shortgeometry(2"lap)3.8mm,steel
0.60
0.70
0.5mm1mm2mm
3.8mm(testedgeom)
0.5 mm
0.40
0.50
2/
GT
8mm 2 mm
0.20
0.30
8 mm
0.00
0.10
0 5 10 15 20 25 30 35 40
cracklength(mm)
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Maximum GT (tension half of cycle) vs da/dN, R = -1
Ref. 6
ADH 1 Adh i R 0 1 d 1 t d b M d
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ADH-1 Adhesive, R = 0.1 and -1, separated by ModeMixity Range (reversed loading 10X higher crack velocity)
R = 0.1 R = -1
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PreliminaryIn Progress:
Define static Gc andfatigue crack growth
range of modes (GI/GII)and R-values experienced
(data for ADH-1).
C k P th (N l t C k Di ti )
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CLS Crack Paths on Section Normal to Crack
Crack Path (Normal to Crack Direction)
Direction Near Adhesive / Laminate Interface
CRACK PATH:
A. Cohesive in adhesiveB. Cohesive along peel surfaceC. Adhesive along strand surface
Expanded View of Path B
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CLS, ADH-1, laminate side CLS, ADH-1, adhesive side
Peel Surface CLS, ADH-5, laminate side
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, ,
Environment
o e ng
Further Test Development