New constitutive equations with internal coupling in piezocomposites

A new theoretical frame is presented for the study of the elastic, dielectric and piezoelectric properties of two-phase piezoelectric composite materials of complex microstructure. Beginning from basic thermodynamic relations, new general constitutive relations for a two-phase composite have been obtained. These new constitutive equations consider in a general and novel way the dielectric and elastic interaction between the composite's components. This approach was successfully applied to the study of porous ceramics, and now its applicability to the study of piezocomposites will be analyzed. Some measurements of 3-3 composites' dielectric and mechanical properties are presented and compared with the results of porous piezoceramics. The existence and influence of these couplings is clearly observed.