Modelling interfacial debonds in unidirectional fibre-reinforced composites under biaxial transverse loads

A numerical study of the onset and growth of debonds at fibre-matrix interfaces, for a fibre bundle under far field biaxial transverse loads, is presented. The behaviour of the fibre-matrix interface cracks was studied by means of a Linear Elastic-Brittle Interface Model (LEBIM). The simplified, but representative, model of an actual unidirectional lamina considered included ten fibres embedded in a matrix cell whose external dimensions were much larger than the fibre radius. The results presented extend the results obtained by the authors in previous studies using a single fibre model. The aim was, firstly to predict the failure loads (critical loads) originating the first debond onset in a small bundle of fibres and, secondly, to verify the unstable character of subsequent debond growth under transverse loads. The failure curves obtained in this simplified problem help to elucidate some aspects of the failure mechanisms of an actual composite material subjected to these kinds of loads.