Presentation of New Model to Calculate Strain Energy Release Rate for a Crack in Composite Structure

Strain energy release rate is the energy dissipated during fracture per unit of newly created fracture surface area. This quantity is central to fracture mechanics because the energy that must be supplied to a crack tip for it to grow must be balanced by the amount of energy dissipated due to the formation of new surfaces and other dissipative processes such as plasticity. In this paper, strain energy release rate for the crack between fiber and matrix is calculated by employing stress analysis method and energy concepts. First, the stresses are determined for fiber and matrix with a crack length of ‘a’ in polar coordinates by using equilibrium equations. Then, by applying the crack growth criteria, the critical crack length is calculated and the effect of the available shear stress between fiber and matrix on the strain energy release rate in the separation region is investigated. The results of the presented method for SiC/LAS composite have been compared with other previous models which admit a remarkable accuracy.