The homogenization of orthorhombic piezoelectric composites by the strong-property-fluctuation theory

The linear strong-property-fluctuation theory (SPFT) was developed in order to estimate the constitutive parameters of certain homogenized composite materials (HCMs) in a long-wavelength regime. The component materials of the HCM were generally orthorhombic mm2 piezoelectric materials, which were randomly distributed as oriented ellipsoidal particles. At the second-order level of approximation, wherein a two-point correlation function and its associated correlation length characterize the component material distributions, the SPFT estimates of the HCM constitutive parameters were expressed in terms of numerically tractable two-dimensional integrals. Representative numerical calculations revealed that (i) the lowest order SPFT estimates are qualitatively similar to those provided by the corresponding Mori-Tanaka homogenization formalism, but differences between the two estimates become more pronounced as the component particles become more eccentric in shape, and (ii) the second-order SPFT estimate provides a significant correction to the lowest order estimate, which accommodates attenuation due to scattering losses.