Commingled yam composites for rapid processing of complex shapes

Commingled yarns of reinforcing and thermoplastic fibres offer a potential for low-cost manufacturing of complex-shaped composite parts, due to reduce d impregnation times and applied pressures during processing. In order to b enefit from this competitive advantage, the process parameters governing co nsolidation must be controlled. In this study, a consolidation model, previ ously validated for unidirectional commingled yarn fabrics processed isothe rmally in a flat matched-die mould, is applied to three other processing te chniques capable of producing complex-shaped composites. Tubes of braided c ommingled yarns were manufactured by bladder inflation moulding. Selectivel y reinforced polymeric parts were processed by compression-injection mouldi ng. Stamp forming was also used to allow high-speed processing of commingle d yarn-based laminates. Besides particular stamp forming cases., for which part deconsolidation occurred, the model predictions were in good agreement with the void content values obtained from specimens consolidated under di fferent processing conditions. This suggests that the consolidation model c an be successfully applied to a wide range of yarn architectures and proces sing techniques. (C) 2001 Elsevier Science Ltd. All rights reserved.