Application of wave propagation analysis for damage identification in composite laminated beams

Interpretation of data measurement is a major challenge for the development of a reliable and effective diagnostic system. This paper presents the experimental results of a proposed damage identification candidate based on the Lamb wave propagation analysis. From the measured time history data of the propagating wave, the traveling time, speed reduction, and wave attenuation parameters are extracted and used as the damage identification variables. Piezoelectric transducers (PZTs) are used as the wave transmitters and receivers. Carbon-epoxy-laminated composite beam specimens with various types of damage, i.e., delamination, saw cut, and impact damage, are evaluated. Post-processing of the recorded signals using wavelet transform allows the isolation of the interested propagation mode and the extraction of the traveling time, which enhance the accuracy of damage localization. The technique is capable of locating the damages and evaluating the damage magnitude. Further, the classification of damage types in the composite structures is recognized and deduced from the examination of the wave propagation pattern after interaction with damages. This study provides the location and experimental wave propagation profiles of three different damages in composite beams (i.e., delamination, saw cut, and impact damage).