Detection of fractures in piezoelectric actuators by pulse response evaluation

Uniaxial piezoelectric multi-layer actuators are commonly operated under a mechanical pre-load to avoid fractures within the fragile ceramic during operation and handling. However, an unintentionally high mechanical shock or electric excitation may cause a delamination along the inner electrodes in the stack. If fractures do exist, the pre-load often eliminates changes in the measurable actuator properties. Furthermore, the stabilizing mechanical pre-load usually hides fractures in X-ray analysis. In this work the development of a non-destructive tool to detect transversal fractures in uniaxial piezoelectric multi-layer actuators is demonstrated.