Experimental investigation of damage detection on composite plates using wave analysis

Accurate interpretation of data measurement is a major challenge for development of reliable and effective diagnostic system. This paper presents experimental results of a proposed damage identification candidate based on Lamb wave propagation analysis. Carbon/epoxy laminated composite plate specimens with various damage, i.e., delamination and impact damage, are evaluated. Damage location is extracted from the measured time history data of the propagated wave and the wave traveling time. Assuming the wave propagates with a constant speed, the summation of the distance from the transmitter to the damage and the distance from the damage to the receiver is constant. The possible damage location combining with the locations of the transmitter and receiver forms an elliptical path, where the locations of the transmitter and receiver serve as the foci of the ellipse. Piezoelectric transducers (PZTs) are used as the wave transmitters and receivers. Post-processing of the recorded signals using wavelet transform allows better isolation of the interested propagation mode and the extraction of the traveling time, which enhance the accuracy of damage localization. Results of the damage location estimation are presented.