Fracture toughness and mechanical properties of glass fibre-epoxy composites

The present study investigated fracture properties and various mechanical properties of a set of unidirectional glass fibre-epoxy resin composites. This set was comprised of samples with volume fraction of fibres in the range 0.29 to 0.75. An identical set of composites was water-boil treated for 7 days, and the effect of this treatment on the above properties was examined. The work of fracture (γ_F) and the fracture surface energy of initiation (γ₁) results were compared with existing theoretical models for the prediction of fracture toughness. It was discovered that the γ_F results agreed with the pull-out model [6], suggesting that this was the major contribution to the fracture energy of the complete process. The γ₁ values corresponded generally with the surfaces formation model [9], proposing that the creation of new fibre, matrix and fibre-matrix surfaces controls the stage of fracture initiation.