Okay, here goes....

I have a Main Assembly that contains several sub-assemblies, including Sub-Assembly-A.  The components of Sub-Assembly-A are mostly mated, and immovable.  However, a few degrees of freedom remain.  They are fixed by mating component faces to faces of other components in Main Assembly.  These mates determine the final geometry of everything.

Now, I need to do an FEA on JUST Sub-Assembly-A to make sure the loads are low enough.  However, the geometry imposed by Main Assembly is important.  If I try to analyze Sub-Assembly-A, the geometry might not be correct because some parts can move.

So, how do I "fix" the geometry imposed by Main Assembly and do the FEA on just Sub-Assembly-A?  It must be straightforward, but I'm just not seeing it.

Thanks in advance!

Yitz