Fracture analysis of ferroelectric single crystals: Domain switching near crack tip and electric field induced crack propagation

A theoretical analysis is developed for cracked ferroelectric single crystals, focusing on domain switching near the crack tip and field induced crack propagation under a pure electric loading. Domain switching near the crack tip is analyzed first, with the local field concentration determined from the linear piezoelectric fracture analysis, and the resulting domain switching zone established from energetic analysis and compatibility consideration. The crack propagation under a pure electric loading is then analyzed using energy release rate based on field induced domain switching near crack tip. It is found that a negative electric field opposite to the original poling direction would induce a stripe domain switching zone near crack tip, which in turn provides driving force for the electric field induced crack propagation. On the other hand, a positive electric field parallel to the original poling direction induces nearly no domain switching near crack tip, and results in no crack propagation. Good agreements with experiments and phase field simulations are observed.