Simulating a car crash using MPP restart method

- June 8, 2023 at 1:15 pm
  
  日凯林
  Subscriber
  
  I used MPP in LSDYNA to perform pre-loading on my frame and then performed a car collision using a restart file. However, the car did not collide with the frame and instead disintegrated in its own place, as shown in the figure. This issue did not occur when I used SMP for simulation. What could be the reason for this?
- June 12, 2023 at 4:44 pm
  
  Jim Day
  Ansys Employee
  
  Please specify the type of restart (simple, small, or full as described in the RESTART section of the User's Manual) and state the version of LS-DYNA you're running.
  - June 17, 2023 at 6:47 am
    
    日凯林
    Subscriber
    
    The version of LS-DYNA being used is R13, and a full restart is being performed.
- June 19, 2023 at 3:31 pm
  
  Jim Day
  Ansys Employee
  
  Are you restarting from d3dump (SMP) or d3full (MPP) data that was written at the end of a dynamic relaxation analysis? If so, I suggest that instead of attempting a full restart (which even if done correctly may exhibit a lack of robustness), you use the drdisp.sif data written at the end of the dynamic relaxation and IDRFLG=2 in *CONTROL_DYNAMIC_RELAXATION to initialize to a prescribed geometry. I invite others with automotive experience to contribute their suggestions/comments.

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