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 reduced impregnation times and applied pressures during processing. In order to benefit from this competitive advantage, the process parameters governing consolidation must be controlled. In this study, a consolidation model, previously validated for unidirectional commingled yarn fabrics processed isothermally in a flat matched-die mould, is applied to three other processing techniques capable of producing complex-shaped composites. Tubes of braided commingled yarns were manufactured by bladder inflation moulding. Selectively reinforced polymeric parts were processed by compression-injection moulding. Stamp forming was also used to allow high-speed processing of commingled 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 different processing conditions. This suggests that the consolidation model can be successfully applied to a wide range of yarn architectures and processing techniques. (C) 2001 Elsevier Science Ltd. All rights reserved.