Mode II interfacial toughening through discontinuous interleaves for damage suppression and control

An investigation is described concerning the interaction of propagating inter-laminar cracks with embedded strips of interleaved materials in E-glass fibre reinforced epoxy composite. The approach deploys inter-ply strips of thermoplastic film, chopped aramid fibres, pre-impregnated fibre reinforced tape and thermosetting adhesive film, ahead of the crack path on the mid-plane of end loaded split (ELS) specimens promoting energy absorbing mechanisms, at low strain rates, through interfacial toughening ahead of the propagating crack.Following experimental mode II tests, the features were observed to imbue an apparent increase in the toughness of the parent material and suppression of crack growth. The mechanism behind the energy absorption and the behaviour of the crack interaction at the boundary of the interleave edge on ingress and egress were analysed using fractographic processes.