Response of a Quasi-Isotropic Laminated Plate to Acoustic Emission Events

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Green, E. Rhian
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Review of Progress in Quantitative Nondestructive Evaluation
Center for Nondestructive Evaluation

Begun in 1973, the Review of Progress in Quantitative Nondestructive Evaluation (QNDE) is the premier international NDE meeting designed to provide an interface between research and early engineering through the presentation of current ideas and results focused on facilitating a rapid transfer to engineering development.

This site provides free, public access to papers presented at the annual QNDE conference between 1983 and 1999, and abstracts for papers presented at the conference since 2001.


This paper is concerned with examining the disturbance propagating in a fiber composite laminated plate following some known internal impulsive event. By modifying the parameters of the source function, it may be possible to achieve good agreement with experimental results. This approach has been adopted by Suzuki et. al. [1] and by Guo et. al. [2] and it has been shown to be successful when applied to a number of different fracture events. The work reported in [1] relates to an istropic elastic material and employs the Green’s function for a half-space, so that the simulated signals only reproduce the earliest arrivals at the receiver. They take no account of any reflections from the bottom of the plate. The authors in [2] deal with a fiber composite laminate and employ the Lamb wave solution based on laminate theory with shear correction in order to produce the simulated response. This is valid for low frequency disturbances at distances greater than some three or four laminate depths from the source to the receiver. However, for receiver positions close to the source, early arrivals arise from rays which either travel directly from the source to the receiver or which undergo reflection at one or more interfaces in passing from the source to the receiver. In order to replicate these early arrivals, it is necessary to make use of the elastic solution based on the detailed structure of the laminate. Green, [3] has reported on the simulation of the surface response in a cross-ply laminate. Here, this work is extended to consider quasi-isotropic laminated plates. The time history of the source is a unit step discontinuity with a smoothly rising ramp, and as in [3], attention is focussed on the effect of varying the rise time. In each case, the source is assumed to be a line dislocation located at one interface within the laminate. The question which arises naturally is whether it is possible to identify the location and nature of the source from the surface response. It will be shown that in certain circumstances, it is possible to determine the location of the source to within one ply thickness and to eliminate certain possibilities when trying to identify the nature of the source.

Fri Jan 01 00:00:00 UTC 1999