Self-consistent modelling of non-linear effective properties of polycrystalline ferroelectric ceramics

A constitutive model for the nun-linear effective behaviour of ferroelectri c ceramics is presented. The model is developed on the basis of the effecti ve medium approximation (EMA), which describes the interaction of the cryst allites in a statistical way. Additionally, a particular simplified domain configuration within the crystallites and the possibility of domain wall mo tion are taken into account. In connection with a thermodynamic criterion f or the domain wall displacement the volume fractions of the domains can be calculated dependent on the crystallite orientation and the applied load in a self-consistent manner. This mechanism leads to an extrinsic contributio n to the effective behaviour. If the domain wall displacement is associated with energy dissipation the macroscopic behaviour is non-linear and hyster etic. (C) 2000 Elsevier Science B.V. All rights reserved.