A semi-analytical method for measuring the strain energy release rates of elliptical cracks: a novel finite fracture mechanics-based failure criterion application

In this study, a fracture mechanics analysis is presented to address the concern of delamination propagation at the interface of a bi-material laminate. In general, the energy release rate at the crack front is the fracture parameter required to study the propagation of cracks. A new three-dimensional finite element technique, for the evaluation of the energy release rate along the interfacial semi-elliptical crack front in hybrid composite-metal substrates, is presented. Using a non-dimensional correction factor, the related equation expresses the normalized energy release rate. A non-dimensional function with non-dimensionalized functional groups is utilized to investigate the effects of several factors. These factors include the variation in material stiffness between layers, the relative thickness of the two substrates at whose interface the analysis is performed, and the effects of two semi-axes of a semi-elliptical crack on the analysis of the correction factor. These non-dimensional function values were derived by employing a careful interpolation technique on a set of finite element solutions, yielding predictions that exhibit accuracy within acceptable range of numerical results.