Fracture of CFRP containing impregnated fibre bundles

Abstract

The fracture behaviour of carbon-fibre-reinforced plastic composites (CFRP) has been studied by using specimens containing fibre bundles which were impregnated with polymer before being incorporated in an epoxy matrix. The results on CFRP with impregnated bundles show that the impact fracture toughness, the crack growth resistance in terms of stress intensity factor, and the specific work of fracture are enhanced by more than 100%, depending on the impregnant material and fibre volume fraction, as compared to the control composites without bundle impregnation. These beneficial effects are attributed to the increased stability of cracking associated with the bridging of fracture surfaces by the impregnated bundles which act as single fibres of huge diameter effectively increasing the fibre pull-out length. Statistical analysis also demonstrates that bundle impregnation can improve the tensile strength of the bundle as well as the uniformity of strength distribution.