Crash Analysis trends in the Automotive Industry Dilip Bhalsod rd China LS-DYNA User s conference

Transcription

1 Crash Analysis trends in the Automotive Industry Dilip Bhalsod rd China LS-DYNA User s conference 1

2 Vehicle models in elements 2

3 Model size today Total number of elements: Simulation time: 250ms Number of CPU s: 480 Run time: 84h Number of elements reduced from (two complete cars) due to memory issues. small overlap 3

4 Cores per job trend 480 cores Numbers of cores per job Increase ~20% yearly 1 core

5 Crash model size Increase trend 14 million elements today Model size increase ~30% yearly 3500 elements In

6 Today s challenges Airbags, material failure, spotweld failure Deformable wheel rims, deflation of tires, Glass failure, dummies, suspension parts breakable 6

7 Required for Validation through CAE Accurate material models Failure in materials Plastics, metal, glass Accurate modeling of tires, material failure in tire models Suspension links, sub-frame need to consider breaking parts Spotweld failure modeling very critical 7

8 Required for Validation through CAE Accurate dummy modeling Human body modeling Airbag modeling Driver, passenger, knee, head-thorax, curtain Deformable barrier modeling 8

9 Challenges of todays crash models 9

10 Challenges of todays crash models Typical crash models now range between 5 to 15 million elements cpus per job Common mesh for Crash, NVH and Durability analysis Possible to move from mpp-lsdyna to hybrid-lsdyna to improve job turnaround times. Ford study of 100 million element model revealed issues for pre-processing, solver and post-processing More than 100 Gb memory needed to load 100 million element model Fringing of plastic strain took several hours Use of different unit system by different departments within a company results in confusion and time loss 10

11 Challenges of todays crash models Material Fracture Sensing Restraint system modeling Positioning seats for different load cases Friction between parts Connectors BOLTS, SPR, SPOTWELD, MIG WELD Sled creation Pulse convert from full vehicle Restraint modeling Automated Bolt Modeling (with Pre-stress) OneStep Forming (Manufacturing data) 11

12 Challenges of todays crash models Chassis modeling Knuckle, ball joints, control arms Electrical cables Windscreen Active hood Ped pro zones mapping Occupant injury report HAZ modeling Strain mapping on fuel tanks from manufacturing process Fabric Tearing and package tear in OOP 12

13 Material Models 29 in Over 300 material models today to capture accurate modeling of materials 13

14 LSTC family of Dummies and barriers 214 shell/solid ODB shell/hybrid IIHS shell/solid AE-MDB ECER95 RCAR Barrier shell RMDB shell MCB rigid PDB barrier

15 LSTC PDB Model Validation for Global NCAP Progressive Deformable Barrier

16 Rigid curved barrier model for FMVSS

17 Laminated glass modeling Accurate modeling of glass critical for: Pedestrian protection Roof crush FMVSS 208 *MAT_280/*MAT_GLASS 17

18 Combined FEA + IGA Accurate geometry Talk 6.2 Current Status of LS-DYNA Iso-geometric Analysis in Crash Simulation Y. Chen, S-P. Lin, O. Faruque, J. Alanoly, M. El-Essawi, R. Baskaran

19 Accurate airbag modeling Driver, passenger, side, curtain, knee... Airbag folding Uniform pressure or CPM method Accurate venting methods Vent holes Porosity Adaptive vents Pushout vents 19

20 Airbag Folding Process Demonstration - Courtesy of Autoliv 20

21 Simulation Folding Driver side airbag folding Curtain bag roll folding 21

22 Simulation Folding packaging curtain airbag 22

23 Simulation Folding Encapsulating airbag 23

24 New airbag venting methods Push out vent 24

25 New Method to capture Accurate Bag Kinematics Current method IAIR=2 Chambers did not get filled in time New method IAIR=4 Courtesy of Autoliv Airbag deformed shapes at 42 ms

26 Improved airbag deployment

27 Multi-Physics 27

28 Coupled Multi-Physics Solver FEM ALE SPH DEM Particle Gas

29 ICFD The Driver benchmark is part of the QA Designed by TUM, Inst. For Aerodynamics. The objective is to perform automotive aerodynamics validation. It is a generic reference model with a modern car geometry. There is wind tunnel experimental data for comparison. LS-DYNA provides excellent agreement with the experimental data. Configuration used in the study F_D_wM_wW. Fastback_Detailed underbody_with Mirrors_with Wheels

30 ICFD DEM coupling Mud and Snow Deposition. Potential applications include drug delivery, erosion of river bed and FSI using particle bonding capabilities DEM with capillary force coupled to a turbulent flow

31 Electric vehicles EM - New battery module What happens to batteries in a crash- short circuit and heat generation Lithium-Ion cell 31

32 Mapping forming effects Automation flow Vehicle Model Choose parts to be stamped Prepare Onestep Model Run LSDYNA Include results to map data into crash Analysis model 32

33 Crash models Automotive companies focus on building body models and using supplier provided models like: Airbag and streering wheel assembly Seat models Steering column Instrument panel With this approach subsystems are validated by suppliers. 33

34 Implicit LS-OPT LS-TaSC Human Body Modeling 34

35 Implicit Roof Crush No speed up Robust Comparable to explicit Satish Pathy and Thomas Borrvall, Quasi-Static Simulations using Implicit LS-DYNA 35

36 LS-OPT MDO: Vehicle Crash and Body Dynamics 6 Crash Modes + Body Dynamics Mode: - approximately 3 million element models Allen Sheldon, Ed Helwig (Honda R&D) 36

37 Shape optimization LS-TaSC Example: Bottle opener Starting design and load cases Material: plastic Desired mass fraction 0.4 Geometry Constraint Extrusion 2.LC v0 = 0.3 mm ms 1.LC v 0 = 0.3 mm ms 37

38 Results Shape optimization LS-TaSC Example: Bottle opener From Initial Design to Optimized Structure (density distribution) Start from solid 1st Principal Stress End with mass optimized shape Iso-surface 38

39 Human body models Today s research interest interests in the automotive industry A number of companies are actively working in this area 39

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