Nonlinear behavior of ferroelectric materials

An extensive experimental study is conducted to investigate the nonlinear behavior of ferroelectric material due to domain switching. The nonlinear behavior of ferroelectric material is measured under various loading conditions including combined electrical and mechanical loading. By studying various characteristics of nonlinear behavior the mechanism of 180° degree polarization reversal of ferroelectric ceramic material is identified. The effect of residual stresses and electric field on domain switching and hence on nonlinear behavior are also studied. Various parameters for verifying domain switching criterion and developing computational model are obtained from the experimental investigation.; The existing domain switching criteria are reviewed and the predictions are compared with the experimental results. The predictions of the existing domain switching criteria are not satisfactory on comparison with experimental results and hence a new domain switching criterion based on internal energy density is developed. The new domain switching criterion depends on the driving forces required for the particular type of switching and depends only on the current state. The predictions of the new criterion are verified with experimental results and good agreement is found.; A rigorous computational model based on microstructure is developed. Various modeling issues, like representative volume element (RVE) and the effect of residual stress and electric field on domain switching are identified. Solution methodologies for such issues are derived and computational model based on incremental finite element method is developed. The prediction of the nonlinear behavior under mechanical load by the present model is better than the prediction by the existing models. However, the prediction of nonlinear behavior under electrical load shows no improvement over the existing models and potential reasons for this are discussed. Based on the findings of the present study, important issues requiring immediate attention for future research are identified.