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Hi!
I have been working for a long time on calculating the stresses induced by a thermal loading in a power module's assembly. I am only considering uniform temperature variations imposed to my multi-layreed structure, so I do not use the heat transfer module, but only the structural mechanics one.

I considered a 2D-axisymmetric model as a first approximation. My problem is that one of the investigated layer is a solder joint. The solder material used has a viscoplastic behavior that is either described with the Anand's model or with another PDE system that allows to calculate the creep deformations. I have been looking for an example of implementation of a PDE mode coupled with a 2D-axisymmetric geometric but was not succesful. So, I hope that someone on the forum can help me, please :)

Here are my questions related to the coupling of the PDE and COMSOL mechanics' model:
- is it ok to choose a 2D model to define the PDE? (I suppose it was the case since the geometry is basically viewed as 2D but wants confirmation, please);
- do I need to set a specific boundary condition for the boundary located at r=0 to take into account the symmetry? I used to set Dirichlet conditions with all fields at 0 (q=h=r=0);


Thank you very much in advance for any information you may bring me.
Vanessa