Fully Coupled Thermal-Stress Converagnce Problems
Fully Coupled Thermal-Stress Converagnce Problems
(OP)
I am attempting to run a fully coupled thermal-stress analysis on two aluminum plates. I am using hex elements (C3D8T) with about 3000 elements. I can run the model when the mesh is very course but when I try to run the model using a fine mesh to the model will not converge. I do not know why this is happening if anything I would expect it to not converge using the course mesh.
Also is there a limit on the aspect ratio i.e. the length, width, and height of a hex element?
I can post the model if needed.
Thanks
Also is there a limit on the aspect ratio i.e. the length, width, and height of a hex element?
I can post the model if needed.
Thanks





RE: Fully Coupled Thermal-Stress Converagnce Problems
delta_t>function(density, conductivity, element size ^2)
However, documentations states that this is not an issue with first order elements.
Any relevant warning messages, about why the solution diverges?
Material softening at high temperatures may lead to local instabilities (which can be mesh dependent).
RE: Fully Coupled Thermal-Stress Converagnce Problems
corus
RE: Fully Coupled Thermal-Stress Converagnce Problems
I really don't why this worked. Do you all know why this worked when I changed the increment size and what that does in the model. I'm sure this is in the documentation but sometimes it is better to here it from a actual person.
Thanks
RE: Fully Coupled Thermal-Stress Converagnce Problems
corus
RE: Fully Coupled Thermal-Stress Converagnce Problems
When I see that the time increment keeps going below what I have set for the minimum I go to the mesh verification and see what the minimum stable time increment is and then set the minimum to be below that. That usually works, but I can see that it might not do the trick if the problem is due to a discontinuity from changing contact conditions during a run.
HTH,
Dan
RE: Fully Coupled Thermal-Stress Converagnce Problems