Discussion Forum

Hello everyone,

Right now, I am trying to solve a coupled physics problem involving deformation and electric current. In essence, what I want to do is correlate electrical resistance between two spheres for varying applied loads. Based on previous work, we know that altering the applied force changes the spheres' contact area and, hence, the final electric resistance. TO implement this in COMSOL, however, there are a few issues I'm running into. Now, as you can imagine, there is an insulation boundary condition along the surface outside of the contact region. However, inside the contact region, current should be able to run freely between the spheres.

When trying to implement this insulation BC, there's a major issue in COMSOL. If I start with the undeformed geometry, then there is no contact region, and the entire surface is set as an insulation boundary. What I need to do is apply this boundary condition ONCE the deformation has taken place, but there is no way to do this at all. I have tried many suggestions before. Of those suggestions, one is to use the moving mesh (ALE) module to use the deformed geometry in the electric current module. Unfortunately, this does not work - since the entire surface is treated as insulated. Similarly, I also tried to export the deformed mesh into a new geometry via the "remesh deformed configuration" option. Again, this does not seem to work; the mesh is deformed inside the simulation, but the exported geometry is no different than the original geometry. The only difference is that the contact point is shifted vertically; the surface deformation is NOT exported. Is there any way that I could run the elasticity module and THEN apply this insulation boundary condition - such that current may run freely between the spheres? ANy suggestions are GREATLY APPRECIATED; this has been beyond frustrating....