ELECTRIC-FIELD-INDUCED CRACK GROWTH AT ELECTRODE EDGE IN PIEZOELECTRIC CERAMICS

Abstract

Small crack growth behavior in poled lead zirconate titanate was examined under cyclic electric loading. A crack located at the edge of a partial electrode grew along the electrode boundary during the loading. The crack growth rate decreased with increasing crack length until a non-propagating crack was reached. The growth rate and crack length of the non-propagating crack were affected by the amplitude and bias levels of the electric loading. In the case of high-amplitude loading or negative-biased loading, the crack growth rate varied considerably because of domain switching. Finite element analysis of a three-dimensional permeable crack showed that the mode III stress intensity factor range is independent of crack length, but it decreases as a result of the frictional force of a positive electric field. Fracture surface observations showed that intergranular cracking is dominant near the tip of the non-propagating crack.