Domain Switching and Crack Tip Opening Stress Variation in Ferroelectric Ceramics

Evolution of switching zone near a crack tip in ferroelectric ceramics is calculated using the constitutive equations proposed in [1], with an assumption that switching-induced internal fields are minimized by fine domain microstructures and moving charges. A two-dimensional ferroelectric ceramic specimen that has an edge crack and that is poled perpendicular to the crack plane are subjected to external stress and electric fields. Diverse crack tip microstructures are obtained depending on both the history and the ratio of electric and stress loads. It is shown that opposite crack tip opening stresses under the same electric fields are due to opposite distributions of piezoelectric coefficients in the specimens with different crack tip microstructures.