The fracture behaviour and toughness of woven flax fibre reinforced epoxy composites

Epoxy matrix composites reinforced with woven flax fibre textiles having fibre volume fractions greater than 30%, were prepared by a vacuum infusion process. The effects of varying, (i) textile yarn linear density, (ii) textile weave configuration and (iii) the stacking sequence of the textiles, on the fracture behaviour and fracture toughness (K1c) of the composites, was investigated. It was found that the addition of woven textile resulted in a 2–4 times improvement in K1c over that of the unreinforced epoxy, with a value of around 6 MPa m1/2 being obtained for a cross-ply laminate. Both fracture behaviour and K1c were found to be strongly dependent upon the linear density of the weft yarn and the direction of crack propagation with respect to the orientation of the textile, however, the influence of weave type was not significant. It was concluded that toughness is dominated by the fibre volume fraction, rather than the reinforcement architecture.