Travelling cracks in elastic materials under longitudinal shear

Abstract

The solution for the stress field around the tip of a crack subjected to longitudinal shear (antiplane strain) and travelling with a constant velocity in an elastic medium, as given by Bilby and Bullough (1954), has been extended to a configuration analogous to the tensile case studied by Craggs(1960). As in the case of tensile cracks, the applied stress required for constant velocity is lower for higher crack velocity and there is a critical velocity approximately 0.6 times that of the shear wave velocity above which the crack will branch. Similar stress levels are found using two different fracture criteria : the Griffith energy criterion and the criterion of critical shear strain averaged over a critical area.