LOCAL VARIATIONS OF THE DYNAMIC ELASTIC-MODULUS AROUND RUNNING CRACKS

The variation of the dynamic elastic modulus in the immediate vicinity of the tip of the running crack was studied through an iterative proc edure, based on the theoretical expressions for the stress-field compo nents and the experimental relation between strain rate and elastic mo dulus. It was found that the elastic modulus varied strongly around th e tip of the crack, both in radial and polar sense. Also it was observ ed that the polar distribution of the elastic modulus presented clear off-axis extrema in directions that were in good agreement with experi mentally measured branching angles, thus indicating a possible relatio n between these two phenomena.