DRAPING SIMULATIONRecent achievements and future trends

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Dr. Sylvain Bel – LGCIE – University Lyon 1

DRAPING SIMULATIONWhy ? How ? What ?

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DRAPING SIMULATION – WHY ?9/24/2014

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thanniversary LCCFig. 2: Matched-Die Press forming for prepreg

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Only a few examples of draping processes are given here. Of course, also other draping processes exist as well!

ClampsPunch

FabricDie

Resin

Fig. 1: Matched-Die Press forming for dry fabric before RTM

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DRAPING SIMULATION – WHY ?9/24/2014

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Goals & Challenges:� building of a complex shape (3D) without defects� final fiber alignment should be suitable for structural

loads of the final part � less or no cutting scrap (near-net shape preforming)� high fiber volume content (final fiber distribution)� low production cycle time� high quality and reproducibility

[Hancock 2006]

DRAPING SIMULATION – WHY ?9/24/2014

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A combination of the deformation modes enables the textile to be formed in a 3D shape

Elongation Shear

Bending

Inter-ply movement

Transverse compression

Undeformed square of fabric

DRAPING SIMULATION – WHY ?9/24/2014

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Fibre Elongation Inter-fibre Shear

Fibre buckling

Fibre straightening

Inter-fibre sliding

Fibre bendingUndeformed square

of woven fabric

A combination of the mesoscopic deformation modes leads to macroscopic deformations

DRAPING SIMULATION – HOW ?9/24/2014

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The forming behavior of a homogenous material (e.g. metal sheet) canbe easily describe with Hooke’s Law. Describing the forming behaviorof a textile is not straight forward. The Young’s modulus and theshear modulus of a textile are decoupled from each other. They arenot coupled via the Poisson’s ratio.

���������

= �����

1 � 0� 1 00 0 2(1 + �)

������

2���

Hooke’s Law for Plane Stress for Homogenous Materials

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=�� ? ?? �� ?? ? ��,�

������

2���

Constitutive Law for Plane Stress for Textiles(“?” Matrix Entries are dependent on the type of textile)

DRAPING SIMULATION – HOW ? Macro-level Approach9/24/2014

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To have a realistic textile behavior suitable composite elements have to be chosen.

Composite Material Model PAM-FORM (ESI)

Shell Formulation

Composite Element

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DRAPING SIMULATION – HOW ? Meso-level Approach9/24/2014

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The FE draping simulation at mesoscopic scale is based on common 2D/3D elements.

Ø Each yarn is modeled separately.

~ 105 DOF

~102 DOF

[Hamila 2010]

DRAPING SIMULATION – WHAT ?9/24/2014

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Material characterization

Material modelling

Software development

Comparison - validation

Draping simulation

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DRAPING SIMULATION – WHAT ?

�� � �� ∗ ��

�� 2� � ��. cos

�2 � sin

�2 �

��2� � ��

. ���2

[Airbus Helicopters] [LCC/GE]

DRAPING SIMULATIONNowadays at the LCC

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DRAPING OF THERMOPLASTIC PANELS9/24/2014

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• Thermoplastics sheets/panels• Impregnated or comingled with thermoplastic resin• Draped at high temperature (over temperature at melting point)• Thermal dependency

Deep drawing for thermoplastic prepreg

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CF/PA6 : raw material, plate before and after consolidation[LCC] [LCC]

DRAPING OF THERMOPLASTIC PANELS9/24/2014

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Composite Material Model PAM-FORM (ESI)

Shell Formulation

Composite Element

Parameters :

• Tension modulus• Shear modulus• Bending modulus• Viscous behavior• Thermal behavior• Friction

Investigations on the thermo-viscous behavior

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Reproducible test, no mention of folds or wrinkles

[Harrison 2004] : “Shear characterisation of viscous woven textile composites: a comparison between picture frame and bias extension experiments”

ØPicture Frame test on Twill woven thermoplastic composite

DRAPING OF THERMOPLASTIC PANELS9/24/2014

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Picture Frame test on a CF/PA6 sheet at 280°C[LCC][LCC]

• Wrinkles, almost from the start of the test• Sliding, clamp pressure at high temperature• Thermal expansion of the rig

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“Due to unavoidable misalignments, of the 35 tests that were conducted, only 7 were found to meet [the following] conditions”

1. the result should be the lowest force curve produced under a given experimental state (rate, temperature)

2. the result can only be used up until wrinkling of the specimen is observed during the test

3. the data should be physically consistent

[Harrison 2013] : “Press forming a 0/90 cross-ply advanced thermoplastic composite using the double-dome benchmark geometry”

ØPicture Frame test on uniaxial cross-ply sheet comprised of two layers of unidirectional glass-PP plies, with a 0/90 initial fiber orientation

DRAPING SIMULATIONWhat’s coming next…

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MATERIAL CHARACTERIZATION : THERMOPLASTICS COMPOSITE

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Dynamic Mechanical Analysis System

Single Cantilever Double Cantilever

3 points bending (20mm) 3 points bending (50mm)

[Margossian2014]

• Test method

o Setup: 3 point bending (20 mm)o Specimen: 1mm thickness

• Procedures

o Procedure 1: Temperature influence o Heat up to specified temperature at 10°C/min → 200°C,

220°C, 230°C, 240°C, 260°C, 280°Co 5 minutes isothermalo Quasistatic tests at 500 μm.min-1

o Procedure 2: Loading rate influenceo Heat up to 280°C at 10°C/mino 5 minutes isothermalo Quasistatic tests at specified loading rates → 100 μm.min-1,

500 μm.min-1, 1000 μm.min-1, 5000 μm.min-1, 10000 μm.min-1

MATERIAL CHARACTERIZATION : THERMOPLASTICS COMPOSITE

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[Margossian2014]

MATERIAL CHARACTERIZATION : THERMOPLASTICS COMPOSITE

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[Margossian2014]

• Strong temperature and displacement rate dependencies → visco-elastic behaviour

• Inaccuracies in the application of the loading rates at the beginning of the testare noticed for some cases (due to actuator accelaration)

THERMOPLASTICS AND PREPREG COMPOSITES9/24/2014

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[Wang2014, Lyon] [Harrison2013, Glasgow]

[Sachs2014, Twente]

THERMOPLASTICS AND PREPREG COMPOSITES9/24/2014

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Material characterization of prepreg materials at forming temperatureü Complex and attractive topicü Requires new methods

Material modeling of such materials is onerousü Time dependentü Temperature dependent

Software development should enable the thermoforming simulation

ü FE modeling with both mechanical and thermal calculation ??

THANK YOU FOR YOUR ATTENTION

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BIBLIOGRAPHY¢ [Hancock 2006] The use of kinematic drape modeling to inform the hand lay-up of

complex composite components using woven reinforcements, Composite Part A, 2006¢ [Hamila 2010] Textile Composite Reinforcement forming simulation, Numerical

methods and simulation, 2010¢ [Pickett 2011] Analysis and process simulation of textile structures, 2011¢ [Boisse 2011] Simulation of wrinkling during textile composite reinforcement

forming. Influence of tensile, in-plane shear and bending stiffnesses, Composites Science and Technology, 2011

¢ [Harrison 2004] Shear characterisation of viscous woven textile composites: a comparison between picture frame and bias extension experiments, Composites Science and Technology, 2004

¢ [Harrison 2013] Press forming a 0/90 cross-ply advanced thermoplastic composite using the double-dome benchmark geometry , Composites Part A, 2013

¢ [Margossian2014] Flexural characterisation of unidirectional thermoplastic tapes using dynamic mechanical analysis, ECCM, 2014

¢ [Wang2014] Thermo-mechanical behavior of stretch-broken carbon fiber and thermoplastic resin composites during manufacturing, Polymer Composites, 2014

¢ [Sachs2014] Bending characterisation of UD composites, 2014

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