(Comsol 5.5, Structural mechanics, 3D model)
I have a part which contains an initially flat boundary surface (top surface in sketch). Upon application of boundary conditions that do not act directly on that surface, the surface moves and deforms.
How can I constrain the movement in a way such that all nodes on that top surface move the same amount in Z, but freely in X and Y? Almost like a Roller, that can move "globally" up and down. In other words: The nodes on the surface are allowed to move absolutely in Z, but not relatively to each other.
I tried both the roller and periodic boundary conditions, but then, the surface does not move at all in Z.
I assume I will have to use Weak Constraints, but what Constraint Expression can I use? Thank you!