Effects of inter-tow angle and tow size on carbon fibre friction

Friction plays an important role in the processing behaviour of fabrics or prepregs into geometries that require significant inter-ply and intra-ply movements. In previous studies, coefficient of friction is generally assumed to be constant. This paper presents a detailed experimental investigation of the frictional behaviour of carbon fibres at meso-scale. The inter-tow angle was found to have a significant effect on the tow friction when the fibres are parallel; whereas the effect of tow size was marginal. A numerical model was developed to investigate inter-filament friction from tow friction using finite element analysis. The filament-to-pulley friction was found to have a significant effect on the overall load–displacement behaviour, unlike the filament-to-filament friction. A range of intra-tow filament-to-filament friction coefficient was also indicated within which the inter-filament slippage began.