Influence of Fiber Ratio of Composite Materials on Mode III Delamination in ECT Specimens

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. Also influence of fiber volume ratio on fracture toughness in mode III (JIII) was numerically evaluated. 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. It was observed that JIII increased with the increase of crack length. Also fracture toughness in mode III increased with decrease of fiber volume ratio. 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.