A constitutive model for thermo-electro-mechanical behavior of ferroelectric polycrystals near room temperature

A constitutive model that can be used to predict thermo-electro-mechanical linear and nonlinear behavior of ferroelectric polycrystals near room temperature is proposed. A ferroelectric polycrystal is modeled by an agglomerate of 210 single crystallites that are distributed regularly over all directions. A variant in a single crystallite is characterized by a Gibbs free energy function whose coefficients have linear dependency on temperature. A dissipation inequality for domain switching is derived from the restriction of the second law of thermodynamics. Domain switching process is governed by a viscoplastic switching law with temperature-dependent switching parameters. The responses of the proposed model to electric field and mechanical stress loading at room and elevated temperatures are calculated and compared qualitatively with experimental observations available in literature.