Piezocomposites of complex microstructure: theory and experimental assessment of the coupling between phases

A new theoretical framework is presented for the study of the elastic, dielectric, and piezoelectric properties of two-phase piezoelectric composite materials of complex microstructure. These kinds of materials are usually analyzed by means of averaging models. This paper begins with basic thermodynamic relations and obtains new general constitutive equations for a two-phase composite. These new constitutive equations consider in a general and novel way the dielectric and elastic interactions between the two components and provide a method of measuring or calculating these interactions, as well as their influence on the global behavior of the composite. Some measurements of the dielectric, mechanical, and piezoelectric properties of 3-3 and 0-3 composites are presented and compared with the results of both this new approach and an averaging model.