Fracture toughness behaviour of carbon fibre epoxy composite with Kevlar reinforced interleave

This work was to evaluate as to how mode II fracture toughness GII is affected by interleave having Kevlar fibre reinforcement in the fracture plane. Thermoset interleave and chopped Kevlar fibres were applied between the carbon/epoxy composite layers. An artificial crack starter was implanted in the mid-plane to initiate the fracture process. The following five different types of carbon fibre/epoxy composites were prepared and tested. (a) Base laminate without interleave, (b) unreinforced interleave and (c) 0.5, 1.0 and 1.5 mg/cm2 chopped Kevlar fibre reinforced interleave. Results obtained show that fracture toughness GIIC enhanced up to about two times in all the laminates. However, enhancement in fracture toughness GIIC was more effective in interleaved laminate than Kevlar reinforced interleaved because of large energy absorbing capabilities of interleaf. Mechanism of fracture and toughening were examined by using scanning electron microscope.