Abstract
Experimental investigations were carried out to characterize fracture and fatigue behaviours of an actuator piezoelectric ceramic under the combined loading of a high electric field and a mechanical stress. Results show that there exists a strong anisotropic effect on fracture toughness and electric field induced fatigue crack growth in polarized PZT. It is found that the surface fracture toughness in the orien -tation parallel to the polarization direction is much higher than that in the transverse orientation. Under a positive electric field, increasing electric field intensity reduces the fracture toughness in the transverse orientation but enhances that in the parallel orientation. However, the reverse is true under a negative electric field. Low electric field intensity does not result in fatigue crack growth in PZT. For a relatively high applied electric field, the cracks initially grow fast and then are arrested. This result is very significant for the long-term durability of PZT actuators.
