Crack growth behavior in piezoceramics under cyclic loads

Fatigue tests using compact tension specimen of PZT-4 under various combinations of electric and mechanical load were conducted to develop a crack growth model. Experimental results indicated that crack growth could be significantly influenced by electric fields. It, however, cannot be accounted fur by the stress intensity factor alone. In this study, the mechanical strain energy release rate is shown to be a single parameter that can account for both mechanical and electrical loads. Based on the fatigue test results, a fatigue crack growth model in terms of a single parameter was established. Furthermore, the model is extended to explain the crack growth for Vickers indented specimen subject to electric fields. It is noted that the residual stress coupled with electric field causes the growth of Vickers indented crock.