Hi If you suppress the washer surfaces that came over as well as the solid part, does the solid part have the face split at the washer diameter or not?
You have to figure out how to split the face of a solid in Catia, so that you can bring over a solid with pre-split face in order to avoid opening the geometry in SpaceClaim.
If I understand, you want to vary the shape of the part in Catia and bring over the solid and run the analysis. Do you have the Catia-ANSYS CAD interface license so that you can pass design parameters from Catia to Workbench? If so, then you have the right idea.
If you don't have a Catia-ANSYS CAD interface, then you may be better off learning DesignModeler or SpaceClaim in order to add parameters to the imported geometry and let the shape optimization occur within ANSYS without going out to Catia. The reason is you can set up a Design Exploration study that can automate the search for an optimum shape.