Modelling of the effective linear behaviour of piezoelectric ceramics

The paper focuses on the overall linear elastic, piezoelectric and dielectr ic response of polycrystalline piezoelectric ceramics. The effective materi al behaviour is calculated using the effective medium approximation and tak ing into account the domain structure of the crystallites. The model consid ers the full electromechanical interaction coupling of the grains with thei r surroundings in a statistical way. The actual domain structure depends on crystallite orientation and applied load, leading to the minimum of potent ial energy of the system. Thus, the model gives the possibility to predict intrinsic as well as extrinsic contributions to the linear behaviour of pie zoelectric ceramics. Numerical results for the effective properties of unpo led and poled BaTiO3 ceramics are presented. They show a strong effect of e xtrinsic contributions to the effective dielectric and piezoelectric consta nts.