Abstract
Fatigue crack propagation tests of poled and non-poled PZT specimens were performed under mechanical loads with and without superposition of electric fields. The crack length was evaluated from the change of compliance of the specimen. For specimens which were poled in the longitudinal direction (PL specimens) perpendicular to the crack plane, the crack propagation rate for the case of open circuit was faster than that for the case of short circuit. The application of a negative or positive electric field accelerated the crack propagation rate and the amount of acceleration was larger for the case of the negative field. The relation between the crack propagation rate and the stress intensity factor (SIF) can be divided into three regions. In Region I, the crack propagation rate decreases with increasing SIF, and then turn to increase in Region III. In Region II, the propagation rate is nearly constant. The mechanisms of crack propagation in PZT under cyclic loading was discussed on the basis of microscopic observation.
