3D reinforced stitched carbon/epoxy laminates made by tailored fibre placement

Tailored fibre placement (TFP) preforms made of carbon fibre were 3D reinfo rced with aramid, polybenzoxazol (PBO), polyethylene and polyester fibres a nd vacuum injected with epoxy resin. The effects of stitch distribution and stitching process parameters on Mode I interlaminar fracture toughness wer e analysed using a statistical approach. Stitch distribution had a minor ef fect but 3D thread tension had to be carefully chosen to gain optimum mecha nical properties. PBO fibre provided the most improvement in fracture tough ness. 3D reinforcing with aramid fibre reduced tensile and flexural propert ies by 3-8%. Low velocity impact damage in TFP was larger than in fabric bu t smaller than in tape laminates. Compression-after-impact strength was par tly increased by 3D reinforcing in some circumstances but no improvement wa s found under other conditions. (C) 2000 Elsevier Science Ltd. All rights r eserved.