Experimental Investigation of Residual Stresses in Layered Materials Using Moire´ Interferometry

As two dissimilar materials are bonded or cocured at elevated temperatures, residual stresses result upon cooling the layered material system to room temperature. It is well known that the free edges of composite laminates experience interlaminar stresses during applied mechanical or thermal loading. These stresses are significant and must be understood. Current experimental methods are not capable of determining the residual stresses along free edges where failure is likely to initiate. This paper describes the initial findings of a novel experimental technique that uses moire´ interferometry and material removal to determine the residual stress distribution resulting from elevated temperature processing at the free edges of layered materials.