Hi HAB!,

Is the fixed support a correct way to model this structure? A fixed support is a problem when you have a large thermal expansion happening if that does not accurately represent the boundary conditions. This is a rocket nozzle connected to another part of the rocket. You have to model a long enough part of the structure to capture the temperature going from very hot to ambient. Are you using symmetry in the model?  Please post some screen snapshots of the model.

You can create a named selection to see where the distorted element is in the model. Is it near the Fixed Support?  If so, the solution may be to change from a Fixed Support to three displacement constraints that allow the nozzle to expand without picking up stress from the displacement constraints.

Do any of the materials have plasticity or other nonlinear behavior?  If so, you may need to use Substeps to take smaller load increments.

You can change the Contact Stiffness to get rid of that warning.

Please create a Workbench Project Archive and attach that after you post your reply.