Abstract
High-modulus RAE carbon fibres were placed in a resin matrix on an aluminium backing and strained. The behaviour near breaks in the fibres was examined. If the interface was weak the broken fibre ends slid back in their holes in the resin and the load in the fibre was transferred by friction at the interface over a distance of about 1·2 mm. The mean frictional shear force was about 6 MN m−2 (800 lbf in−2). There was little interaction between adjacent fibres in small bundles, and three-dimensional composites broke in a fibrous manner.
If the interface was strong the load was transferred from broken fibres mainly elastically over a distance of about 130 μm. In bundles of a few fibres a crack in one spread to the others, and three-dimensional composites broke in a brittle manner.