Mesh of Assembly vs. Assembly of Meshes

You can compile the mesh for simulation of an assembly in two ways. You can create one mesh of the entire assembly (mesh of assembly), or you can create a mesh for each part in the assembly (assembly of meshes).

See Also
Automated FEM: User-Driven Options

By default, the Automated FEM creates one child FEM representation for each leaf product to be meshed and one FEM representation that assembles all the child FEM representations. This is known as an assembly of meshes. Alternatively, you can change the Automated FEM execution options to create one FEM representation for the entire assembly (a mesh of assembly). The following image displays how each type of meshing references the geometry of each part in an assembly:

Mesh of Assembly
One mesh is created at the assembly level for geometry of the entire assembly. The mesh references the 3D Shape representations for each part within the assembly to mesh the entire assembly. This option can be faster to configure, but does not provide as much control for specific parts of the mesh.
Assembly of Meshes
A mesh is created at the part level for each part in an assembly. Each mesh at the part level references the 3D Shape representation for that part. There is also one mesh at the assembly level that assembles the meshes for each part. With an assembly of meshes, you can configure the FEM representation for each part. This can be useful to configure meshes differently for parts with different geometries.