Effect of electric cyclic loading on fatigue cracking of a bending piezoelectric hybrid composite actuator

Fatigue damage development in bending piezoelectric hybrid composite actuators with different lay-up configurations under electrical loading cycles is addressed in this work with the aid of an acoustic emission (AE) technique. Electric cyclic fatigue tests have been performed up to 107 cycles on the fabricated bending piezoelectric hybrid composite actuators. The applied electric loading range is from −150 voltage to +150 voltage. To confirm the fatigue damage onset and its pathway, the source location and distributions of the AE behavior over the fatigue range are analyzed. In conclusion, electric cyclic loading leads to piezoelectric fatigue damage such as trans- and intergranular micro-damage and long path main cracking on the surface of the PZT ceramic layer, thereby degrading the displacement performance. However, this fatigue damage and cracking do not result in final failure of the bending piezoelectric hybrid composite actuator loaded up to 107 cycles. In particular, investigation of the AE behavior and the linear AE source location reveals that the onset time of the fatigue damage varies considerably depending on the existence of a GFRP protecting bottom layer.