Mechanics of splitting in orthotropic materials

Abstract

A theoretical study is made of splitting around the boundaries of elliptical holes in an orthotropic material. The splitting is modeled as a crack with both Mode I opening and Mode II sliding. The sliding resistance on the closed portion of the splitting crack is assumed to obey a Coulomb friction law. The stress intensity factors and the critical external load for splitting propagation are calculated as functions of splitting length. The dependence of stress intensity factors and the critical external load upon the length of splitting, the root radii of the hole, elastic orthotropy, frictional coefficient and the critical energy release rate is described in terms of a universal set of nondimensional parameters. It is found that splitting is unstable in the absence of frictional resistance and stable when sufficient frictional resistance is present. Elastic orthotropy, through its interaction with frictional resistance, tends to reduce the effects of frictional sliding resistance.The stress redistribution due to splitting is also studied. It is found that the splitting is very effective in relieving the high stress concentration ahead of the tips of cracks or at the boundaries of holes. Unlike the growth of splitting itself, the stress redistribution effect is insensitive to frictional resistance. The calculated results suggest that regardless of the root radii of a flaw, a splitting crack of the length of the original flaw reduces the stress concentration factor to less than 2.