Computer-aided assessment of debonds in laminates from shearographic fringe patterns

Abstract

Shearography has shown to be a potentially viable non-destructive testing technique, especially for the detection and evaluation of debonds in composites. With this technique, debonds in an object are revealed readily from anomalies in the shearographic fringe pattern; these anomalies also enable accurate estimation of both the size and depth of debonds. For the technique to be acceptable to industry, it would be useful to automate the interpretation of fringe patterns so that prior knowledge of shearography is not required of the shop-floor operator: this paper demonstrates that such an objective can be realised. Digitization and storage of shearographic fringes are first performed using an imaging device connected to a personal computer, after which the operator will examine the stored image for debonds. Finally, estimation of the size and depth of the debonds detected will be automated using a computer programme. © 1991.