Low frequency bending piezoelectric actuator with integrated ultrasonic NDE functionality

A bending piezoelectric actuator has been manufactured with a 250 μm thick PZT plate embedded in five layers of unidirectional fiber Kevlar epoxy. The selected orientation of the fibers produces a gradient of residual stresses in the composite that enhances bending actuation. By segmenting the electrodes, it is possible to launch an ultrasonic pulse in the actuator so that structural health monitoring of the actuator itself can be performed using pitch catch ultrasonic NDE during the low frequency actuation. Qualitative experimental results of fatigue tests and damage detection are presented.