The image below shows that I can run a frequency analysis for a single piece by specifying which surface comes in contact with noise/vibration under 'fixtures.'

I am trying to do something similar with a cylindrical shell hanging by springs from a metalic piece.

The metalic piece is going to be the source of vibration and I want to know how that vibration will transmit through the springs and excite the cylindrical shell (assembly shown below).

I would appreciate it if I could be provided with some guidance as to how best to do it.

As can be seen below, I can run frequency simulations of assembly files with the cylindrical shell and top and bottom caps on.

But if I attempt to do the same with the springs (cosmetic), screws, and the ceiling the springs hang from, I get an error message with the mesh for some reason.