Hi Vaclav,

In order to understand shear stiffness K_t, I tried to model 2 particles analysis under shear loading on concrete particles. One particle is fixed while the other moving in the direction perpendicular to the line connecting 2 spheres' center. Which later on I change to rotation and then combine two types of shear motion. However the simulations yield unstable results (as showned)

I have tried to use different material parameters combinations, and numerical parameters, the results are still absurd.

Is there any approach to simulation shear loading of two concrete sphere that you could suggest me? I would be so grateful if you could help.

Thanks in advance,

Giao

Can you put a bit of your script how you prescribe the motion? The response looks pretty harmonic so there might be some forgotten DoF which is responding elastically.