New constitutive relations for piezoelectric composites and porous piezoelectric ceramics

This paper deals with a new system of constitutive relations that describe the elastic, dielectric, and piezoelectric behavior of piezoelectric composite materials. Porous piezoelectric ceramics saturated with different fluids and epoxies are an example. These relations are obtained from basic thermodynamic considerations and are applicable to a great number of different cases. This new theoretical approach takes into account the mutual influence between the different components of the composite and provides a novel procedure to analyze this coupled behavior, Experimental results concerning the elastic and dielectric properties of porous piezoelectric ceramics saturated with different polymers and oils are also presented. The,influence of the coupling mechanisms on the material parameters is analyzed. The advantages of using this theory as opposed to other averaging approaches to study this type of materials are clearly shown. (C) 1996 Acoustical Society of America.