Domain switching induced stresses at the tip of a crack in piezoceramics

Abstract

The singular stress and electric fields in the vicinity of a crack or flaw in piezoelctric ceramics lead to ferroelectric domain reorientation. The mismatch strain develops due to the domain switching and the stress field around the crack tip could be thus perturbed and the apparent fracture toughness affected. The present study investigates the effect of domain switching on fracture toughness. A domain switching criterion is proposed and validated with experimental data. A finite element based algorithm in conjunction with the domain switching criterion is developed to analyze the stress and electric fields and the resulting domain switching zone in a compact tension specimen of PZT-4. It is found that the size and mode (90° or 180° switching) of the domain switching near the crack tip depends on the magnitude and direction of electric fields. The stress intensity factor is increased or decreased depending on whether the applied electric field is positive or negative. The predicted variation of fracture toughness with respect to the electric field agrees with the experimental data.