Acoustic Emission from Internal Delamination of a Four-Ply Plate
The basic inverse source problem of acoustic emission is the determination of the nature and location of the internal source from surface measurements of the transient elastic waves generated by the AE event. As pointed out by Sachse , this inverse problem requires a knowledge of the dynamic Green’s function for the structure under examination. The evaluation of this dynamic Green’s function is therefore a pivotal problem in the application of the techniques to monitor internal events in engineering structures. This paper deals with the determination of the transient motion of a four-ply fiber composite laminate resulting from an internal impulsive line load acting in the mid-plane of the plate in a direction normal to the mid-plane. The source function for acoustic emission associated with delamination will be located at one or other of the interfaces between the plies and the results presented here complement those of the earlier paper  which deals with an impulsive line load acting on the upper interface. Because of symmetry, the response to a line load at the lower interface may be deduced immediately from this upper interface solution.