Composites Science and Technology vol:54 issue:2 pages:147-159
The bond between a fibre and the matrix is very important for the mechanical behaviour of CFRP. The quality of the fibre/matrix interface will influence the initiation and development of damage. This is certainly true for interlaminar fracture toughness. The present study is focused on the modelling of the influence of the interface properties on the fracture toughness of CFRP. Carbon fibres with four different wet oxidative treatment levels were investigated. The fibres were embedded in an epoxy resin and in a thermoplastic system. Mode I, mode II and mixed-mode tests were performed to determine critical study-energy release rates. A micromechanical model was developed to explain how fracture toughness of the interface influences the initiation fracture toughness of the composite. A second model explains the R curve behaviour for mode I tests by analysing the strain in a single fibre bridging a crack.