On the thermomechanics of composites with imperfectly bonded interfaces and damage

General connections are established between the mechanical and thermal responses of composite materials with debonded or imperfectly bonded interfaces, and with internal cracks or cavities. In particular, such results are found for multiphase composites or polycrystals in which normal and/or shear displacement jumps may exist at interfaces or cracks, consistent with complete debonding or with the presence of a nonlinearly elastic interphase layer. In two-phase systems with isotropic phases and sliding interfaces, we also recover exact connections between the mechanical and thermal stress or strain fields in the phases.