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Convergence Problems with contact simulation

Convergence Problems with contact simulation

Convergence Problems with contact simulation

(OP)
Hello Everyone


I know this is a common problem in ABAQUS (or at least it is for me). I'm trying to run an impact simulation of a basic bumper impacting a discrete rigid barrier. Clearly this is a dynamic model with surface-to-surface contact interaction. To avoid convergence problems, I allow for an automatic time step (ABAQUS defined time steps). However, the time steps are ridiculously small (around 1E-6 to 1E-5) and this would cause my simulation to take weeks to complete. However, if I define the time steps as more reasonable increments (around 0.01) there are convergence problems.

Previously I would always use automatic time steps, but these increments are far too small. Is there any method or trick I can use to make the time increments larger and the simulation faster? This is a real problem if I have to use time steps of 1E-6. I know contact simulations typically yield convergence issues, so there must be some methods to deal with this problem in a reasonable way. Any ideas?

More info on my simulation: A deformable bumber impacting a discrete, rigid barrier in a dynamic explicit analysis. Surface-to-surface contact is used. Time steps are set to automatic, but are way too small.


Any insight would be greatly appreciated. LEt me know if you need for information.

thanks

RE: Convergence Problems with contact simulation

1E-5 is not that small. How long does the impact take? About 1 sec? With a very large model (500000 DOF) this would run about 8h on a decent workstation (what is called an "overnight" run). If you are only modeling the bumper, this is more a 100000 DOF problem and would take 2h, which is not bad for an explicit calculation.

Are you sure you are not having e.g. memory issues (using slow swap memory) or I/O problems?

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