Dynamic micromechanical model for smart composite and reinforced shells

Abstract

A dynamic micromechanical model based on the asymptotic homogenization pertaining to smart composite and reinforced shells with piezoelectric and piezomagnetic constituents is developed in this paper. Central to the work is the recovery of the so-called unit cell problems which allow the calculation of the effective coefficients. In turn, these are substituted into the governing equations to obtain a set of basic macroscopic variables which eventually yield asymptotic expansions of all field variables (mechanical stress, electric and magnetic displacement, heat flux etc.). Highlights of the presented dynamic model include the following: (1) the effective properties of the homogenized structure depend strongly on the curvature of the middle surface of the shell; (2) the effective properties are also temporal functions and not merely spatial ones as predicted by other models; (3) the effective properties reflect the influence of all involved constituent material parameters; and (4) the model captures not only the common product properties (magnetoelectricity, pyroelectricity, pyromagnetism) but also other ones relating current density to mechanical displacement, magnetic field, and temperature. These features essentially mean that the homogenized shell is characterized by inhomogeneity or quasi-homogeneity after the homogenization process and also exhibits memory effect reminiscent of viscoelastic structures. If electrical conductivity is ignored and the effective properties are averaged over the entire time spectrum the results of the model converge to those of previously published quasi-static models. If, as well, the electrical and magnetic effects are also suppressed the results of the model converge to those of the classical composite shell model.