THE USE OF A COHERENT GRADIENT SENSOR IN DYNAMIC MIXED-MODE FRACTURE-MECHANICS EXPERIMENTS

THE USE of a coherent gradient sensing (CGS) apparatus is explored in dynamic fracture mechanics investigations. The ability of the method to quantify mixed-mode crack tip deformation fields accurately is tested under dynamic loading conditions. The specimen geometry and loading follow that of Lee and Freund who gave the theoretical and numerical mixed-mode K values as a function of time for the testing conditions. The CGS system's measurements of K(I) and K(II) are compared with the predicted results, and good agreement is found. The method is used to measure K beyond the time domain of the known solution: it is seen that a shift from primarily mode II deformation to primarily mode I deformation occurs.