Acoustic Emission in a Fiber Composite Plate

Abstract

Acoustic emission techniques are being widely used for the detection of faults in engineering structures. These techniques allow the possibility of real time monitoring of large areas of in-service structures, with a high probability of crack detection (see e.g. Granata et. al. [1], Jacobs et. al. [2]). A prerequisite for this application is a thorough understanding of the nature of the stress waves generated as a result of internal impulsive events. A number of authors have examined the problem both theoretically and experimentally and the reader is referred to [2] for a list of references. Amongst these in particular, Ceranoglu and Pao [3] have made a comprehensive theoretical and numerical study of the transient response of an isotropic plate to a variety of dynamic nuclei of strain They show plots of the time histories of both the normal and tangential surface displacements at the epicenter and at radial distances of two, four and six plate thicknesses from the source location. Results are presented for surface sources and buried sources located at the mid-plane of the plate. The surface sources consist of normal, tangential and oblique step function point loads, whilst the buried forces include also double forces, couples, centers of explosion, centers of rotation and double couples without moment.