Spectrotemporal analysis of guided-wave pulse-echo signals: Part 2. Numerical and experimental investigations

Part 2 of this paper seeks the numerical and experimental procedures for implementing the Morlet wavelet transform for the spectrotemporal analysis of multimode dispersive waves. The sensitivity due to the spectral parameters α and w_o, defining the bandwidth and center frequency of the mother wavelet, is studied through an error analysis of the simulation signals. The algorithm for determining the group delays is extended to multimode signals by introducing a thresholding technique. The ultimate goal of this study is to nondestructively detect and locate discontinuities in a thin plate. This is demonstrated by experimentally measuring the travel distance of a Lamb wave from a single waveform.