Average electro-mechanical properties and responses of active composites

This study deals with the overall electro-mechanical response of randomly positioned spherical particles reinforced piezoelectric composites. Different composites comprising of linearly elastic and piezoelectric constituents were studied. For the piezoelectric constituent, both linear and nonlinear electro-mechanical coupling behaviors were considered. Numerical representative volume elements (RVEs) were generated and finite element (FE) method was used in order to compute overall electro-mechanical response of the RVEs. The electro-mechanical predictions of the RVEs were compared against those of Mori-Tanaka, self-consistent and simplified unit-cell micromechanical models. A new first moment secant linearization was introduced in order to perform the homogenization of the nonlinearly piezoelectric composites followed by iteration in order to minimize errors (residual) from the linearization. For all boundary conditions, including nonlinear response, simulated in this work, the predictions given by the Mori-Tanaka and UC models were reasonably close to the ones of the RVE cases. Finally the RVEs were modified to examine the linear and nonlinear electro-mechanical responses of piezoelectric ceramics with pores. Depending on the prescribed boundary conditions, the existence of pores could significantly alter the electro-mechanical response of piezoelectric ceramics.