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Collision of Solid Blocks

Hi,

I have two blocks colliding at 200 m/s. The impact causes an insane deformation in the solids, which doesn't make any sense. When I set the velocity low to about 10 m/s, I get something reasonable. I'm wondering how I can simulate for high velocities?

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Radioss

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tinh

Scale down the time step. High speed impact needs small time step.

If a rocket flying to you at 200m/s, you must displace faster (shoter time) than in case of a bike moving 10m/s, otherwise you'll bloom!

Simon Križnik

Hi,

given the impacting object's high kinetic energy (KE = 71940 J or 430x the energy of a .22 rifle bullet) fragmentation on impact is expected.

However, From Radioss help:

Depending on the material law, the solid elements are not deleted after the criteria εpmax is reached (they do not appear as “deleted elements” in post-processors).

For Material Laws 2, 4 and 22, only the deviatoric part of the stress tensor is set to zero, the internal pressure of the solid is still computed.

On the other hand, for Material Laws 3, 23, 28 and 36 the solid elements are deleted when εmaxpεpmax is reached.

As a workaround, define FAIL/TENSSTRAIN card to get a more realistic fracture behavior.

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Crashphys

Both suggestions were incredibly helpful. I reduced the element size by one half and defined FAIL/TENSSTRAIN as recommended. Simulation runs exactly as expected now, with results showing something more realistic.