Mixed-Mode Dynamic Stress-Intensity Factors from Caustics
SourceIn this paper the experimental method of reflected caustics was used for the evaluation of the dynamic stress-intensity factors KId and KIId for running cracks propagating under constant velocity. The elastodynamic equations for the reflected caustics formed from light rays reflected from the vicinity of the instantaneous position of the tip of the running crack were established for the case when the crack propagation velocity was considered as constant. The distortion of the form and the relative position of the created caustic for the dynamic case as compared to the respective static one were studied for various types of mixed-mode deformation of the cracked plate. An experimental application of the method to cracked plates made of an elastic and isotropic material [poly(methyl methacrylate) (PMMA)] indicated the potential usefulness of the method.