Just sharing some of my learning (win the hope that it may benefit some newcomers like myself) ... BTW - if this should be posted elsewhere then please tell me
I modeled a stiff object embedded in a soft matrix subjected to shear (see Test43_0.jpg). This to learn about Mesh Groups, Material Groups, Boolean Fragments, how to select hidden solids, etc. etc. I attach the model as Test43.fcstd
In the process I also installed useful tools like "addons_installer.FCMacro" and using this the "Lattice2" workbench.
Here a summary of the workflow:
1) created 2 cubes in PART workbench and placed one at the center of the other
2) created BooleanFragments (resulting in 3 solids) ... set mode to CompSolid !
3) apply a CompoundFilter (can't mesh BooleanFragments?!)
4) copy this and "explode" it into 3 separate solids with Lattice2 for later reference in creating internal mesh groups, internal material groups and (if needed) internal boundary conditions (although I have not thought of a practical application for this)
5) Create a mesh using the CompoundFilter and create Mesh Groups using the associated Solids from the exploded compound
6) Do the same with materials and boundary conditions
and Presto ... this meshes (GMSH) and computes (CCX) without out a problem.
Finally I attach 2 ParaView screenshots (Test43_1.jpg and Test43_2.jpg) to show that the stiff core indeed remains largely undeformed.
Wow .... that was good fun !!