Khashayar Ghaffari
Ansys Employee
Like the error suggests, the issue is that one of the surfaces of the specified contact, is shared between different materials. This will be an issue since the work function for surface has to be determined. As you mentioned to address this you can use a single material for all of the contacts. ItÔÇÖs worth noting that itÔÇÖs not possible to use metals in the simulation without them being defined as a contact.
Regarding choosing a geometry for contact, structure groups as a whole would be available for selection, however not the sub-components within them. If you are interested in selecting a particular geometry as contact, consider moving them out of the group. If this is for the metal components mentioned earlier, it would make sense to apply the contact to all the adjacent geometries.