Influence of fiber ratio of composite materials on mode III delamination in ECT specimens

In the present study, fracture behaviorof woven fabric-reinforced glass/epoxy compositelaminates under mode III crack growth wasexperimentally investigated and numericallymodeled. Also influence of fiber volume ratio onfracture toughness in mode III (JIII) wasnumerically evaluated. Two methods were used forthe calculation of the strain energy release rate: theexperimental compliance calibration method andthe virtual crack closure technique. To achieve thisaim, edge crack torsion was used to evaluatefracture toughness in mode III loading (out ofplane-shear) at different crack lengths. Load–displacement and associated energy release rateswere obtained for various cases of interest. It wasobserved that JIII increased with the increase ofcrack length. Also fracture toughness in mode IIIincreased with decrease of fiber volume ratio. Boththe experimental compliance method and thevirtual crack closure technique proved applicablefor the interpretation of the fracture mechanicsdata of woven glass/epoxy laminates in mode III.