Fracture source location in thin plates using the wavelet transform of dispersive waves

A new signal processing approach was presented for acoustic emission source location using the dispersive waves in a thin plate. For wave propagation in dispersive media, the accuracy of source location can be improved by usi ng the arrival times of a single frequency component in the output signals at an array of sensors. The wavelet transform (WT) was used to resolve this problem. By utilizing the time-frequency data of the WT, the frequency-dep endent arrival time traveling with the group velocity was shown to be easil y determined. Experiments were performed using a lead break as the simulate d fracture source on the surface of an aluminum plate. Two plate modes corr esponding to the So and Ao Lamb waves were identified, and their group velo cities were accurately measured. The source location results based on the W T method agreed well with the true locations. The WT method was also compar ed with the cross correlation technique, and both methods provide similar r esults.