A shadow moire technique for the measurement of damage in composites

Abstract

The purpose of this paper is to show that a simple form of shadow moire technique can be effective when applied in assessing the extent of damage in and stability of laminated composite materials. Typical shadow moire records of the out-of-plane displacement contours are shown for areas of damage in a carbon fibre/epoxy specimen under applied compressive loads, and for a composite repair patch on a cracked metal coupon under applied tension. The results are obtained using an optical system consisting of off-the-shelf components of low cost. The design of the system was restricted by the emphasis on simplicity and cheapness, nevertheless the performance is well suited to the application. It is hoped that simple out-of-plane field measurement techniques will be more widely used in the future to obtain the data needed to understand the sometimes complex behaviour of laminated composite materials. © 1985.