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Dr. Roger A. Assaker CEO, e-Xstream engineering

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Presentation on theme: "Dr. Roger A. Assaker CEO, e-Xstream engineering"— Presentation transcript:

1 Bridging the Gap between Autodesk Moldflow and Nonlinear FEA of Reinforced Plastic Parts
Dr. Roger A. Assaker CEO, e-Xstream engineering Chief Material Strategist, MSC Software

2 Class Objectives To learn about the latest developments in modeling nonlinear behavior of structures made of fiber reinforced plastics, including: Long Fibers & MuCell Materials Injection and Compression Molding Compression Fatigue and Creep Performance High Performance Computing

3 Class Structure Introduction & Motivation Compression Molding
Long Fiber Reinforced Plastics MuCell Fatigue Creep Hybrid Solution Procedure

4 Introduction & Motivation

5 Composites in Automotive

6 Opportunities: Weight Reduction
Average/Indicative Facts: 1995  2005: +17% of mass (1118 kg1310kg) +200 kg  +18% of Fuel consumption (4.8 l/100km  5.7 l/100km)  Objective : -200 kg or -15 to 20 g CO2/km by 2020 Plastic parts: interior, under the hood, … Optimize using advanced CAE/Material Modeling Optimize design: e.g. engine mount: -40% weight & -15% in cost Reduce thickness Part consolidation Metallic parts: Platform, Cabin Frame, Skin,… Optimal mix of materials : Plastics, Composites, …

7 Mutli (Composite) Materials

8 Chopped Fibers/Injection Molding
Fully aligned flow Flow lines Weld lines

9 Challenges of Reinforced Plastics
Process-dependent (Local) Moldflow (Fiber orientation) Nonlinear Stain-rate dependent Anisotropic

10 Process  Material  Structure
Material Processing Injection molding Compression modling D-LFT Material Microsturcure Chopped fibers Nano, ... Material Chracteristics Mechanical Thermal Electric, ... Structural Performance Stiffness Strength Fatigue, …

11 Material Behavior: Measured
Source: LKT, Prof. Drummer Friedrich-Alexander-Universität Erlangen-Nürnberg Skin-core effect Source: DatapointLabs e-Xstream Users‘ Meeting 2011

12 Measured Properties  FEA ?
Material properties from ISO 527 specimen Average orientation OT{Trace} = [ 0.80 | 0.15 | 0.05 ] Scaling (factor = 0.6 – 0.8) Material properties from injection molded plate 0° properties Scaling (factor = ???) 0° / 30° / 45° / 60° / 90° properties Reverse engineering Skin-Core effect OT = [ multi-layer RVE ] Global isotropic Local anisotropic

13 Local, Nonlinear, Anisotropic Material
Loading ISO 527 100% 2D 36% IM 22%

14 Local Results: Plastic Strain
equivalent scaling isotropic anisotropic With Moldflow & Digimat) Without Moldflow & Digimat)

15 Local Results: Weldline
Fiber orientations Accumulated plastic strain in material matrix

16 Materials: Long Fiber Thermoplastics (LFT)

17 LFT – Effect of Fiber Waviness
Tortuose Straight

18 LFT – Effect of Fiber Bundling
s11 [MPa] e11 Without bundling With bundling ~ 2300 MPa ~ 2800 MPa + ~ 500 MPa

19 LFT - Effect of Bundling in Digimat-MF
ar = 50 ar = 5 + 5% fibers 5% bundling s11 [MPa] e11

20 Materials: MuCell

21 MuCell RVE Generation 15 % fibers 20 % voids
Source: 15 % fibers 20 % voids

22 Strain Distribution in the Microstructure
Tensile Direction mean local Tensile Direction

23 MuCell: Effect of Void on the Material Stiffness

24 MF vs FE modeling of MuCell
7.8% voids 15% voids

25 MuCell: Distribution of the VF of Air Inclusions

26 MuCell: 3-Point Bending Beam

27 MuCell: Armrest Vertical Load

28 MuCell: Horizontal Side Impact

29 MuCell: Horizontal Impact CAE Performance Curves

30 Performance: Fatigue

31 Chopped Fiber Reinforced Plastics: Fatigue Analysis Workflow
DIGIMAT reinforces the fatigue life computation at two levels: Computation of the unit load case (Digimat-CAE/Structural) Computation of the fatigue life prediction (Digimat-CAE/Fatigue)

32 Fatigue: Chopped Fiber Reinforced Plastics

33 First Pseudo Grain Fatigue (FPGF) Model
Ply composite Using fatigue failure criteria (i.e. Tsai-Hill) Pros : Different « strengths » per direction, multi-axial Cons : Purely meso/macro if not coupled with multi-scale methodology Tsai-Hill S: Fatigue strengths depending over N (nb cycles to failure) 1/L: Fiber direction 2/T: Transverse direction Users workflow Exp measurement: S-N curves measured for 0°, 45° 90° UD specimens Material modeling: Define the measured S-N curves and corresponding microstructure (0° vs 90°) Fatigue solution: Prediction of local S-N curves in each integration point (ply in each element) of the FE model, accounting for any Stress amplitude Mean stress Loading direction / Fiber alignment Damage accumulation:  Miner’s rule Tensile 0° Tensile 90°

34 Fatigue of Chopped Fiber Reinforced Plastics
Unit Load: Stress S11 Fatigue life

35 Creep & Relaxation

36 Creep & Relaxation

37 Creep: Affine vs General vs Spectral vs FE

38 Thermo-ViscoElasticity

39 Thermo-ViscoElastic Relaxation

40 CPU Optimization: Digimat Hybrid

41 Hybrid Solution Procedure

42 Crush Simulation: Digimat-CAE/LS-Dyna

43 Digimat Nonlinear Micro Material Model
Bumper Beam impact Material definition Digimat v4.3.1 Viso-plastic propety FPGF failure Tsai-Hill-2D strains Micro: strain base Hybrid: stress base Mircostructure Morphology Orientation Length: Short Fibers (AR=20) Weight Fraction of Fibers Isotropic Use MD property from Digimat-MF result Viso-plastic property Failure : end point of MF curve MD FPGF failure defined at this strain-rate TD

44 Optimal Domain Decomposition
Optimization Decomposition Default decomposition 29 domains have no Digimat elements Digimat elements in 3 domains Improved decomposition Digimat elements in 22 domains 10 domains have no Digimat elements Optimized decomposition Almost same as improved but all domain has Digimat elements.

45 CPU Performance: Digimat vs Isotropic
Hybrid Hybrid 16 cores 32 cores 64 cores Iso (improved) 17 h 59 m 9h 17m 10h 0m Hybrid (default) - 42h 31m 26 h 37 m 14h 16m 8 h 15 m (optimized) 12h 5m Micro 152 h 51 m (6.4 days)

46 Conclusions Reinforced Plastics is a light weight alternative to metals Advanced CAE, including nonlinear multi-scale material modeling , enables effective & efficient design of reinforced plastic parts by Taking advantage the process simulation done with Moldflow The latest developments in Multi-Scale Material & Structural Modeling support: Long Fiber and MuCell Fatigue and Creep Performance Hybrid Solution Procedure and HPC make Nonlinear Multi-Scale a efficient solution procedure for accurate part and system simultion

47 Autodesk, AutoCAD* [*if/when mentioned in the pertinent material, followed by an alphabetical list of all other trademarks mentioned in the material] are registered trademarks or trademarks of Autodesk, Inc., and/or its subsidiaries and/or affiliates in the USA and/or other countries. All other brand names, product names, or trademarks belong to their respective holders. Autodesk reserves the right to alter product and services offerings, and specifications and pricing at any time without notice, and is not responsible for typographical or graphical errors that may appear in this document. © 2012 Autodesk, Inc. All rights reserved.

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