Towards a numerical model of the compressive strength for long fibre

The compressive failure of long fibre composites is tackled as a structural instability that is initiated by plastic microbuckling. A homogenised mode l is proposed to take into account the fibre initial waviness, the non-line ar matrix behaviour and some structural effects. The problem is formulated at the ply scale by using a two-scale displacement field and a specific fin ite element is developed to reduce the extent of computations. This numeric al tool permits us to rapidly determine the failure of various unidirection al ply configurations by use of a maximum load criterion. The results estab lish the influence of some structural parameters on the compressive failure strains, as has been observed in related experiments. They also explain th e high compressive strength achieved under flexural loading. (C) Elsevier, Paris.