Effect of stacking sequence and geometric scaling on the brittleness number of glass fiber composite laminate with stress raiser

The fracture behavior of quasi-brittle material exhibits commonly brittle behavior with some ductility in the fracture processing zone. Therefore, a matrix of experimental works is performed to investigate the failure behaviors based on a parameter known as brittleness number, which is a measure of brittle behaviors. Glass fiber-reinforced epoxy laminates of three stacking sequences, cross-ply [0/90]2s and two quasi-isotropic [0/45/90]2s and [0/45/90/-45]s, are manufactured using hand lay-up technique. A matrix of different specimen geometric scaling with open hole of the same material is used. The fracture energy GIC and nominal strength of these composite laminates are measured experimentally using compact tension test, center crack specimen, and tension test, respectively. The results showed that the increase of homogeneity of composite laminates, which is introduced by inserting a certain angle ply for the laminate structure, enhanced the material ductility as the brittle number increased. The larger size of specimen leads to the increase of brittleness for the same stacking sequences due to the increase of stress concentration factor.