Application of wavelet transform on modal acoustic emission source location in thin plates with one sensor

Abstract In this article, the theory of the wavelet transform and modal acoustic emission are used to analyse the propagation of elastic waves in thin plates. Based on the theory of modal acoustic emission, the acoustic emission (AE) signals are mechanical in nature. When they propagate in wave-guided, they have multi-mode and dispersion characteristics. The separation of the modes at the sensors could make it possible to extract the exact information about the source that produced the waves. Based on the modal nature of AE, it can be understood that a good location would have two methods to determine the arrival times. One is determined on the same part of the waves (not only the same mode, but also the same frequency) at all sensors. The other is determined on the different modes at one sensor, which makes it possible to reduce the number of sensors needed. In this article, an acoustic source location technique with one sensor is brought out. First, through modal analysis of the propagation of elastic waves in a thin plate, the dispersion characteristics of the modes are predicted. Second, the wavelet transform theory using Gabor wavelet is briefly outlined and its application in elastic waves is explained. It is shown that by using the peak of the magnitude of the wavelet transform, the arrival times of the different modes can be determined. Additionally, experiments were undertaken using a lead break on the edge of the plate. These demonstrated the feasibility of the one sensor linear location scheme.