The application of automatic fringe analysis in fracture mechanics

Abstract The likelihood of propagation of a crack in a metallic plate under load can be assessed by evaluating an energy-based contour integral, the J integral, for the loaded specimen. Calculation of the integral requires that the local stresses in the specimen are known. These stresses can be obtained practically by the use of strain gauges or by moire fringe methods. This paper describes a semi-automatic, computer vision-based method of calculating the J integral when moire fringe methods are used to evaluate the stresses in the specimen.