Erik Kostson
Ansys Employee
Hi

For nonlinear convergence issues, these can be related to material, geometric and contact nonlinearities (nl). We are at the moment trying to help you with this part. Troubleshooting this is quite a challenge sometimes and takes lots/some nl simulation work to get an idea of what causes it. Some guidelines are here (but for nonlinear contacts and the other type of nl):
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Of course default and program controlled is a good start when using contacts, so I am not saying that we should not use it. Here though, we are just trying to understand the reason for the non-convergence, which could be as we said due to the contact. So we are just trying to find the reason, and nothing else really, so that is really the reason why I suggested MPC :) . So in order to exclude or study the contacts we would ideally get rid of them and use shared topology where the mesh is shared between parts (this is fine as long as our contact is bonded). So try sharing the topology in SC to get rid of the contact, or if this is not possible let's try as we said to use MPC and see if that helps. Again we are just trying to find out why it is not converging (not saying that default program controlled is not OK), so that is all really with this. If it works with shared topology, then we know is due to the contacts, and then we can address that in detail (so try and see why), or we can just use shared topology and that is fine for bonded contact :).

Now I would recommend a course if you want to know more about the different type of contacts and contact modelling :
https://courses.ansys.com/index.php/courses/contact-mechanics/

For MPC contacts we can look at this (contact tech. guide in ansys help):
Chapter 10: Multipoint Constraints and Assemblies

Let us know how it goes when eliminating the contacts with shared topology (video below shows how to do that), or if not possible using MPC. Also if you could share some info of the model (BC), contacts, loads,....., that would make it easier for us to give you some feedback. Also try remove the contacts and small parts and analyse the main part under the desired loads, and see if that converges.
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All the best

Erik