Experimental and analytical characterization of acoustic emission signals

The identification of crack growth signals is extremely important in order to effectively use acoustic emission techniques to detect, locate, and determine the significance of an internal flaw. The results of an analytical methodology, incorporating a source model that is an actual crack propagation and arrest event, are presented in this paper to predict a time dependent acoustic emission signal. The integral equation method is used to calculate the dynamic Mode I stress caused by a crack propagating with a prescribed velocity, after which the displacements at any point are calculated. These time dependent displacements are the analytical form of the acoustic emission waveforms. An experimental procedure, which uses a laser interferometer to measure velocities normal to the specimen's surface, is used to investigate acoustic emission waveforms in a compact tension specimen. The experimental results are used to verify the analytical model.