Acoustic emission source location

The dispersive behaviour of Lamb wave propagation is investigated as a means of establishing the location of Acoustic Emission (AE) signals over long distances. The presence and dispersive behaviour of the flexural and extensional Lamb modes in digitised AE signals is observed in laboratory tests on a 12m long structural steel I-beam. The frequency characteristics of the two modes are compared and modal separation via bandpass frequency filtering is demonstrated. This separation is used to estimate the source-to-sensor distance, as a means of single sensor source location. The method is implemented using software developed in LabViewTM Measurements of peak amplitude attenuation of the extensional Lamb component are used to examine the viability of far-field source location. Important considerations for practical application of the method, and its ability to provide an insight into the identity of an AE source, are outlined. The potential of the technique in structural monitoring applications is briefly discussed.