Effect of volume fiber and crack length on interlaminar fracture properties of glass fiber reinforced polyester composites (GF/PO composites)

Double-cantilever beam (DCB) specimens are widely used to measure the mode I critical-energy release rate G(Ic) of glass-fiber reinforced polyester composites (GF/PO composites). It showed G(Ic) varied significantly during crack propagation. G(Ic) of GF/PO composites are higher than that of the pure polyester (PP) resin because of the additional force required to fracture fiber bridging in GF/PO composites. Comparative DCB tests were carried out to demonstrate the occurrence of fiber bridging. G(Ic) varied markedly and were much dispersed, which would induce little variation when initial crack length was 40 mm. The fracture characteristics were analyzed by scanning electron microscope.