Mode III interlaminar fracture and damage characterization in woven fabric-reinforced glass/epoxy composite laminates

The increasing use of composite materials in industry leads to the need for a detailed investigation on fiber-reinforced composite joints. In the present study, fracture behavior of woven fabric-reinforced glass/epoxy composite laminates under mode III crack growth was experimentally investigated and numerically modeled. Two methods were used for the calculation of the strain energy release rate: the experimental compliance calibration method and the virtual crack closure technique. To achieve this aim, edge crack torsion was used to evaluate fracture toughness in mode III loading (out of plane-shear) at different crack lengths. Load-displacement and associated energy release rates were obtained for various cases of interest. To calculate fracture toughness J(III), two criteria were considered in load-displacement curve which included non-linearity and maximum points; it was observed that J(III) increased with the increase of crack length. Based on the finite element analysis, the recommended crack length range was given in order to design a configuration which would give 97% mode III contribution to the total energy release rate. Both the experimental compliance method and the virtual crack closure technique proved applicable for the interpretation of the fracture mechanics data of woven glass/epoxy laminates in mode III.