Contact caustics measurements expanded to anisotropic materials

Regions with high stress gradients represent critical zones of engineering structures, such as crack tip or vicinity of the contact zone. The optical method of caustics is one of the few experimental methods which provide applicable results in these locations. This method was originally developed for crack-tip measurements of stress intensity factors and J-integral for isotropic and then for anisotropic materials. Subsequently, it was extended to the contact problems, where the size and the shape of caustics are related to the amount and the inclination of loading force. Here, the application of the method of caustics is extended to the analysis of contact problems for mechanically anisotropic materials. This makes the caustics method widely applicable to the analysis of any high stress gradient locations in a structure.