About the Effects of Debonding of PWAS on the Wave Propagation and the Electro-Mechanical Impedance Spectrum
Abstract »The use of piezoelectric wafer active sensors (PWAS) for acousto-ultrasonics (AU)-based structural health monitoring (SHM) purposes is state of the art. This paper deals with these piezoelectric transducers and aims to analyze their performance in case of defects of the PWAS itself. It focuses on the partial debonding of PWAS from the structure. Effects on the generated wave and the electro-mechanical impedance (EMI) spectrum are studied for a disc-shaped transducer with wrap-around electrode. The results show a dependency on the location of the debonded area in relation to the wrap-around electrode. Moreover, a high dependency on the excitation frequency is detected. The relevance for SHM purposes is shown by the analysis of the effects on a simple damage indicator, used for structural damage detection. Possibilities to detect this PWAS defect based on the EMI spectrum are presented.