BEM analysis of inter-fibre failure under compression in composites: comparison between carbon and glass fibre systems

The heterogeneous character of fibrous composite materials implies mechanisms of damage that are frequently associated, at least at the micromechanical level, with the generation of interface cracks and, thus, with interfacial fracture mechanics. The particular case of matrix/interfibre failure, typically appearing in impact problems and in cross-ply laminates, and caused by a dominant traction acting transversely to the fibres, is directly associated to the appearance and growth of cracks at the fibre/matrix interfaces that eventually lead to macrofailure. The present work studies the evolution of this mechanism of damage under compression and compares the results obtained for two different bimaterial systems: glass fibre-epoxy matrix and carbon fibre-epoxy matrix. To this end, a boundary element model of a single fibre cell is performed, and its results are analysed using the concepts derived from interfacial fracture mechanics. The conclusions obtained establish the morphological differences existing in the generation of this mechanism for both material systems, supporting the idea of a weak dependence of the development of the interfibre failure under compression on fibre elastic properties.