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COMPARISONOFFINITEELEMENTCODESFORIMPACTSIMULATIONON

COMPOSITES

Jorge Fernando A. Rojas Ulloa.

Supervisor: Jean-Philippe Ponthot.

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CONTENTS

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INTRODUCTION

Composite materials, given their non-homogenous

nature, need special laws that describe their

behaviour.

Structures with damage have different properties

than non-damaged ones, hence making them

difficult to be studied in a traditional way.

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OBJECTIVES

Parameter sensitivity analysis of a composite

material law with the inclusion of damage.

Use of LS-DYNA to model a low velocity impact in a

composite plate using material law 162.

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METHOD: TEST CASE DESCRIPTION

Slow velocity impact of a rigid ball against a

composite plate

Composite

Plate

Rigid ball

V

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METHOD: TEST CASE DESCRIPTION

Geometry:

Impactor:

A rigid ball, with a radios of 8 [mm].

Composite plate:

12 plies made of a resin HexFlow- RTM6 reinforced with carbon

fibers.

Stacking sequence S]0/45[

3

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METHODOLOGY: MATERIAL LAWS

Three different material laws were used.

Simple orthotropic law: material law 002.

Material law with damage: material law 162.

Cohesive material law: material law 138.

Note: Material law 138 was only used in combination with

material law 162.

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METHODOLOGY: MATERIAL LAW

edfedf

Can only be integrated using one Gauss point, leading tothe appearance of hourglass modes.

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METHODOLOGY: SIMPLIFICATIONS

Only one quarter of the plate is used due to the symmetry

of the problem.

The ball is modeled entirely.

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METHODOLOGY: RUNNING MODEL

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METHODOLOGY: SENSITIVITY ANALYSIS

Method:

Take reference values from literature.

Modify value and generate different test-cases.

Compare results:

Sensitivity = (Val-Val_Ref)/Val_Ref

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METHODOLOGY: SENSITIVITY ANALYSIS

Reference Parameters

Parameters obtained from the proportioned data

Parameters obtained from the literature

Density

[Kg/mm3]

Ea [GPa] Eb [GPa] Ec [GPa] PRBA

1.505e-6 67.4 66.30 13.50 0.0363PRCA PRCB[GPa] GAB[GPa] GBC [GPa] GCA [GPa]

0.0665 0.0676 4.3 4.3 4.3

SAT [GPa] SAC [GPa] SBT [GPa] SBC [GPa] SCT [GPa]

0.897 0.705 0.862 0.679 0.058

SAB [GPa] SBC [GPa] SCA [GPa]

0.103 0.065 0.065

SFC [GPa] SFS [GPa] SFFC [GPa] PHIC ELIMIT

0.850 0.3 0.300 10 0.2

SDELM ECRSH EEXPN CERATE 1 AM1

1.2 0.001 4 0.0 2.0

AM2 AM3 AM4 CERATE 2 CERATE 3

2.0 0.5 0.2 0.0 0.0

CERATE4

0.0

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METHODOLOGY: SENSITIVITY ANALYSIS

Selected parameters:

Softening damage parameter:

AM1 & AM2: 2.0. Fiber failure in warp and fill directions.

AM3: 0.5. Compression in the thickness direction.

AM4: 0.0. Matrix failure and delamination.

Element eroding parameters:

E_LIMIT: 0.2 Strain in the elements.

ECRSH : 0.001 Compression relative volume ratio.

EEXPN: 4

Strain rate parameters:

CERATE 1: 0.0 Strength properties.

CERATE 2: 0.0 Elastic modulus in warp and fill dir.

CERATE 3: 0.0 Shear modulus.

CERATE 4: 0.0 Elastic modulus through the thickness

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METHODOLOGY: SENSITIVITY ANALYSIS

Selected parameters:

Other parameters:

PHIC: 10 Coulomb friction angle.

S_DELM: 1.2 Scale factor of the delamination area.

SFS : 0.3 Shear strengths. SFFC: 0.3 Compressive strength.

SFC: 0.850 Crush strength.

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RESULTS

For demonstrate the procedure the sensitivity

analysis will be performed to the AM1 parameter.

Three different values were found in the literature.

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CONCLUSIONS