Micromechanical Model of a Polycrystalline Ferroelectrelastic Material with Consideration of Defects

Abstract

Constitutive equations for describing the nonlinear behavior of a polycrystalline ferroelectroelastic material are proposed which take into account the dissipative movement of domain walls, the presence of point defects, and their effect on switching processes in the temperature range not accompanied by phase transitions. The method of two-level homogenization is used to describe the behavior of a polycrystalline ferroelectroelastic material at the macro-level. Accounting for defects in the micromechanical model of ferroelectroelastic materials has significantly improved the predictive ability of the model under multiaxial loading. Comparison of the results of computations with experimental data on dielectric hysteresis curves and switching surfaces under nonproportional loading of PZT-4D, PZT-5H, and BaTiO₃ polycrystalline piezoelectric ceramics shows that the proposed model has good prediction accuracy.