The fracture energy of hybrid carbon and glass fibre composites

Abstract

The fracture energy of a model carbon fibre/glass fibre/epoxy resin hybrid composite system has been evaluated as a function of the carbon fibre/glass fibre ratio. Work of fracture measurements were less than a rule of mixtures prediction and a pronounced negative synergistic effect was observed at high carbon fibre and high glass fibre contents. Fibre debonded lengths and fibre pull-out lengths for the carbon and glass fibres were accurately measured using a projection microscope technique. Models of microscopic fracture behaviour, together with these measurements, were successful in quantitatively describing the observed fracture behaviour of the hybrid fibrous composites. It was found that post-debond friction energy provided a major contribution to the fracture energy of the glass fibres. The post debond sliding mechanism was also shown to be primarily responsible for the non-linear behaviour of the work of fracture of the hybrid composite.