Understanding the effect of an electric field on fracture behavior of piezoelectric materials is an important step towards a rational design of smart sensors and actuators. Domain switching has been observed to be the cause of significant nonlinearity in the response of piezoelectric materials subjected to mechanical and electrical loads. While linear piezoelectricity is incapable of explaining the results of the experiments conducted on cracked piezoelectric specimens, a nonlinear analysis considering domain switching is found to be necessary to describe some of the key observations of these experiments. In this paper, the response of piezoelectric solid is formulated by coupling thermal, electrical, and mechanical effects. The corresponding finite-element equations are derived and applied in the solution of the piezoelectric centre crack problem, with different poling directions, subjected to various mechanical and electrical loads. The effects of domain switching are evaluated on the near-tip stresses and the stress intensity factors. It is observed that a negative electric field increases the peak stress intensity factor while a positive electric field reduces it.
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