Stable Growth of Surface Cracks

This paper describes the results of a theoretical study of the stable growth of a part-through crack emanating from a free surface. A three-dimensional finite element program, incorporated with enriched elements at the crack border, is developed to determine the stresses or displacements, or both. Increments of crack growth are predicted by application of the strain energy density theory assuming that the crack profile coincides with the path of minimum strain energy density function, dW/dV. A preset value of (dW/dV) c is used to develop various crack profiles under stable growth while a critical strain energy density factor, S c =r c (dW/dV) c , is assumed to determine global instability that corresponds to the onset of rapid crack propagation.