Application of Wavelet Transform as a Signal Processing Method for Defect Detection using Lamb Waves: Experimental Verification

A Lamb wave-based crack detection method for aluminum plates health monitoring is developed in this paper. Piezoelectric disks are employed to actuate and capture the Lamb wave signals. The position of crack is assumed to be aligned with the sensor and actuator.  Extraction of high quality experimental results of lamb wave propagation in a plate-like structure is considerably complicated due to phenomena such as multimode excitation, wave dispersion, material attenuation, and boundary reflection. The main goal of this study is to utilize a customized wavelet transform technique to purify the captured Lamb wave signals. Significant features of these signals were then extracted from the wave energy distribution. Experimental results show that the developed method has a promising capability in identification of crack positions.