Influence of interface degradation on the performance of piezoelectric actuators

An experimental and numerical study was performed to investigate the effects of interface debonding on the performance of piezoelectric (PZT) ceramic actuators for structural health monitoring (SHM) systems. Interface degradation of PZT actuators may occur over time during the in-service life of the structure compromising the performance and reliability of the SHM system. Energy losses and signal changes should be understood to guarantee the reliability of the SHM systems during the life-time of the structure. Here we present the first systematic study on the performance of PZT actuators with a partially degraded interface. The electro-mechanical coupling between PZT actuators and a hosting aluminium plate was found to vary with the interface debonding over a wide frequency range affecting the amplitude and phase of the actuators signal. A signal delay and an amplitude decrease were observed for: increasing debonding area, different debond shape, and location underneath the PZT actuators. Changes were found to be dependent on the actuation frequency with respect to the PZT resonance frequency. A spectral element-based code integrated with a coupled electro-mechanical field solver was used to verify the experimental results by simulating the propagation of ultrasonic Lamb waves in an aluminum plate with built-in PZT sensors/actuators.