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

An investigation is described concerning the interaction of propagating interlaminar cracks with embedded strips of interleaved materials in E-glass fibre reinforced epoxy composites. The approach deploys interlayer strips of a thermoplastic film, thermoplastic particles, chopped fibres, glass/epoxy prepreg, thermoset adhesive film and thermoset adhesive particles ahead of the crack path on mid-plane of Double Cantilever Beam (DCB) specimens. During these mode I tests, the interlayers were observed to confer an apparent increase in the toughness of the host material. The crack arrest performance of individual inclusion types are discussed and the underlying mechanisms for energy absorption and the behaviour of the crack at the interaction point of the interleave edge were analysed using scanning electron microscopy.