# Simulation Issues

I’m struggling to get my nut staking project to converge. I have a lot of non-linear displacement with plastic deformation. I think the problem is with the Physical Contact. Penalty Method solves well but the results are way off. Lagrange is good but it never fully converges at 100%. The contacts are very non-coplanar and I’m sure this is the issue, but what setup handles this kind of contact the best. Any help would be greatly appreciated.

https://www.simscale.com/projects/cschmidt/nut_staking_-si-/

Hi @cschmidt!

Let me tag our PowerUsers @cjquijano and @BenLewis here who might give you some impetus on this issue. I am also assuming that the “sharp edges” cause too much trouble here but I am not sure if radii will definitely help to overcome this issue.

Cheers,

Jousef

Hi @cschmidt,

I have put together two examples of how I would solve this problem. Here is a link to my project.

https://www.simscale.com/projects/BenLewis/nut_staking_-si-/

In the first example (Simulation Rotated Symmetry 03) I have used your original geometry where there is a line contact between the two parts (and a small gap). In the second example (Simulation Rotated Symmetry 05) I have created a small landing between the two parts (and no gap). This allows the simulation to reach a higher load before it fails.

Here is a list of some of the changes I have made:

• The applied displacement is much smaller. However, the maximum stress is still well over 1000 MPa so I am assuming this will be enough for your needs.
• The mesh is a second order type with refinements in the contact zone for higher quality results.
• A much higher penalty coefficient was used. This greatly reduces the overlap between the two parts for more realistic results.
• The geometric behavior was set to linear as the non-linear option takes longer to solve and the results are basically the same.

Here is an animation of the results.

I hope this helps.

Regards, Ben

3 Likes

Hi Ben,

I think there might be something wrong with the link you provided to the project. Could you please fix this?

Should work now @cschmidt!

Best,

Jousef