Non-linear simple model of tube welded to a plate is not converging

Viktor Antevski

Greetings to everyone!
This is quite common question on the forum, but I will open it again with a simple model so that maybe we will add something new.

non_linear_contact_between_plates.fem

I didn't use excessive loads in the model and the model itself is straight forward rectangular tube welded on a plate. I tried S2S and N2S, I tried clearence 0, I tried using property ID contact definition, I used CNTSTB in the loadsteps, EXPERTNL in the cards, rearranged to SPCs, used even lower loads, thicker plates. I don't use non-linear materials in the model since I am only interested in the non-linear behavior of the contact.

What can go wrong in this situation, is there something I am missing? I will attach the model.

solon

For shell elements, the contact and tie considers the shell thicknesses.

https://help.altair.com/hwsolvers/os/topics/solvers/os/contact_os_c.htm?zoom_highlight=contact#:~:text=for%20Self%2DContact.-,Contact%20Interface%20Padding%20(GPAD),-%22Padding%22%20of%20the

You can control how thickens will be taken into account in PCONT, GPAD field