Time reversal active sensing for health monitoring of a composite plate

The applicability of a time reversal concept in modern acoustics to structural health monitoring was investigated. The time reversal method has been adapted to guided-wave propagation to improve the detectability of local defects in composite plate structures. Specifically, a wavelet-based signal processing technique has been developed to enhance the time reversibility of Lamb wave in thin composite plates. The validity of the proposed method is demonstrated through experimental studies in which input signals exerted at piezoelectric (PZT) patches on a quasi-isotropic composite plate are successfully reconstructed by using the time reversal method. The ultimate goal of this study is to develop a reference-free damage diagnosis technique based on the time reversal process so that defects can be identified without relying on any past baseline data.