Stress intensification due to polarization switching

Experimental investigations suggest that crack growth in ferroelectric ceramics under alternating electric field appears to be governed by the magnitude of the applied electric field relative to the coercive field, defined as the theoretical strength of applied electric field that is required to induce macroscopic polarization switching. This paper presents the stress analysis for a ferroelectric bar under longitudinal vibration induced by laterally applied alternating electric field. These results indicate that the internal stresses oscillate at a frequency near the system resonance frequency, independent of the frequency of the applied electric field, and the oscillating stresses have substantially larger amplitudes when polarization switching takes place. These indications support the notion that polarization switching intensifies the internal stresses and hence promotes microcracking.