Microcracking and electric fatigue of polycrystalline ferroelectric ceramics

The major obstacle preventing ferroelectric actuators from enjoying wide application is the so-called electric fatigue which results in reduction of actuation displacement/force after actuators have been subjected to many cycles of applied electric field. Experimental observations reveal that fatigued specimens often contain scattered microcracks, and hence suggest that microcracking may be the cause of electric fatigue. This paper presents a theoretical model developed within the framework of continuum electrodynamics for deformable dielectrics, to study the microcracking effect upon macroscopic properties of polycrystalline ferroelectric ceramics. The numerical results indicate that microcracking can indeed cause the observed fatigue behavior.