Discussion Forum

Model builder (Physics) Question
My model is the following:
Thin film of Polyurethane and three hemisphere glass are on the film. The Boundary load will be applied on the top of the three hemisphere equally. And I want to see the displacement change on the surface of the top of the film, which is contact area of hemisphere and film. (flat part of the hemisphere is top and round part is bottom) Hence, I need to apply contact mechanics on this model.

Here are my questions,
1. on the geometry, I am confused that I have to put the hemisphere on the top of the film or do I have to make some distance between them. If I use Identity boundary pair, I think I have to contact those two geometry but if I use contact pair, I think I have to make some space between hemisphere and film. I don't know which one will be better. Plus, when I make a contact or identity boundary pair, the source boundaries will be top part of the film and destination boundaries will be bottom (round) part of the hemisphere right? or Do I have to assume the contact area, make the geometry, and then choose those contact area only?

2. Let's say I make a contact pair. In the Physics(Solid Mechanics) tap, I said the boundary load will be applied on the top of three hemisphere and on the force section, I choose total force (z direction: -F). Fixed Constraint is the bottom of the film, and thin film will be Hyperelastic material and i put the constants needed on material section. And now, I think I have to choose Contact Pair in Pair tap and choose boundaries I set on the definition. And I meshed film finer than hemispheres. Now, I think i have to compute to see what is going on but the code is not converged. I don't know why. Do I miss anything for this part? I actually watched whole videos of comsol in Youtube and I couldn't find what I was wrong. I really need your help for this.