DRAPING SIMULATION Recent achievements and future trends 1 Dr. Sylvain Bel LGCIE University Lyon 1
2 DRAPING SIMULATION Why? How? What?
DRAPING SIMULATION WHY? Clamps Punch Fabric Die 1 2 Resin 3 4 Fig. 1: Matched-Die Press forming for dry fabric before RTM 1 2 3 4 Fig. 2: Matched-Die Press forming for prepreg Only a few examples of draping processes are given here. Of course, also other draping processes exist as well! 3
DRAPING SIMULATION WHY? 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 4 [Hancock 2006]
DRAPING SIMULATION WHY? Undeformed square of fabric A combination of the deformation modes enables the textile to be formed in a 3D shape Transverse compression Bending 5 Elongation Shear Inter-ply movement
DRAPING SIMULATION WHY? Undeformed square of woven fabric A combination of the mesoscopic deformation modes leads to macroscopic deformations Fibre bending Fibre buckling Fibre straightening 6 Fibre Elongation Inter-fibre Shear Inter-fibre sliding
DRAPING SIMULATION HOW? The forming behavior of a homogenous material (e.g. metal sheet) can be easily describe with Hooke s Law. Describing the forming behavior of a textile is not straight forward. The Young s modulus and the shear modulus of a textile are decoupled from each other. They are not coupled via the Poisson s ratio. = 1 0 1 0 0 0 2(1 + ) 2 Hooke s Law for Plane Stress for Homogenous Materials =??????, 2 Constitutive Law for Plane Stress for Textiles (? Matrix Entries are dependent on the type of textile) 7
DRAPING SIMULATION HOW? Macro-level Approach To have a realistic textile behavior suitable composite elements have to be chosen. Composite Element Composite Material Model PAM-FORM (ESI) 8 Shell Formulation
DRAPING SIMULATION HOW? Meso-level Approach The FE draping simulation at mesoscopic scale is based on common 2D/3D elements. Each yarn is modeled separately. ~ 10 5 DOF ~10 2 DOF 9 [Hamila 2010]
DRAPING SIMULATION WHAT? Material characterization Material modelling Software development Comparison - validation Draping simulation 10
DRAPING SIMULATION WHAT? 2. cos 2 sin 2 2. Symposium 5th anniversary LCC 2 11 [Airbus Helicopters] [LCC/GE]
12 DRAPING SIMULATION Nowadays at the LCC
DRAPING OF THERMOPLASTIC PANELS Thermoplastics sheets/panels Impregnated or comingled with thermoplastic resin Draped at high temperature (over temperature at melting point) Thermal dependency [LCC] CF/PA6 : raw material, plate before and after consolidation [LCC] 1 2 3 4 Deep drawing for thermoplastic prepreg 13
DRAPING OF THERMOPLASTIC PANELS Composite Element Composite Material Model PAM-FORM (ESI) Parameters : Tension modulus Shear modulus Bending modulus Viscous behavior Thermal behavior Friction Shell Formulation Investigations on the thermo-viscous behavior 14
DRAPING OF THERMOPLASTIC PANELS [Harrison 2004] : Shear characterisation of viscous woven textile composites: a comparison between picture frame and bias extension experiments Picture Frame test on Twill woven thermoplastic composite Reproducible test, no mention of folds or wrinkles 15
DRAPING OF THERMOPLASTIC PANELS [LCC] [LCC] Picture Frame test on a CF/PA6 sheet at 280 C Wrinkles, almost from the start of the test Sliding, clamp pressure at high temperature Thermal expansion of the rig 16
DRAPING OF THERMOPLASTIC PANELS [Harrison 2013] : Press forming a 0/90 cross-ply advanced thermoplastic composite using the double-dome benchmark geometry Picture Frame test on uniaxial cross-ply sheet comprised of two layers of unidirectional glass-pp plies, with a 0/90 initial fiber orientation 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 17
18 DRAPING SIMULATION What s coming next
MATERIAL CHARACTERIZATION : THERMOPLASTICS COMPOSITE Single Cantilever Double Cantilever Dynamic Mechanical Analysis System 3 points bending (20mm) 3 points bending (50mm) 19 [Margossian2014]
MATERIAL CHARACTERIZATION : THERMOPLASTICS COMPOSITE 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 C o 5 minutes isothermal o Quasistatic tests at 500 μm.min-1 o Procedure 2: Loading rate influence o Heat up to 280 C at 10 C/min o 5 minutes isothermal o 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 [Margossian2014] 20
MATERIAL CHARACTERIZATION : THERMOPLASTICS COMPOSITE Strong temperature and displacement rate dependencies visco-elastic behaviour Inaccuracies in the application of the loading rates at the beginning of the test are noticed for some cases (due to actuator accelaration) 21 [Margossian2014]
THERMOPLASTICS AND PREPREG COMPOSITES [Wang2014, Lyon] [Harrison2013, Glasgow] [Sachs2014, Twente] 22
THERMOPLASTICS AND PREPREG COMPOSITES Material characterization of prepreg materials at forming temperature Complex and attractive topic Requires new methods Material modeling of such materials is onerous Time dependent Temperature dependent Software development should enable the thermoforming simulation FE modeling with both mechanical and thermal calculation?? 23
24 THANK YOU FOR YOUR ATTENTION
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 25