Modelling and analysis of the thermal characteristic of thermoplastic composites from hybrid textiles during compression moulding

A promising strategy to decrease cycle times for manufacturing continuous-fibre–reinforced composites is processing of thermoplastic matrix systems due to their fast processability, since no cross-linking of molecular chains is required as for thermoset resin systems. Nevertheless, thermoplastic carbon fibre-reinforced plastics nowadays are predominantly manufactured with pre-impregnated sheet materials, which result in limited drapability and freedom of design. Hybrid textiles, consisting of thermoplastic and carbon fibres, can avoid these disadvantages. This class of reinforcements combines the drapability of dry textiles with thermoplastic matrices, which furthermore allow near net-shape processes. Relative shifting between the fibres and, consequently, draping is possible in a preforming step. The objective of this article is to expand our knowledge about hybrid textiles with regard to their thermal behaviour during compression moulding. Accordingly, the necessary parameters for modelling the thermal state of the dry textile and the impregnated laminate are investigated. Moreover, an in situ process analysis based on the reflection spectra of glass fibre-optical sensors, which are embedded inside the stacking, is investigated to provide information about the state of aggregation and to validate the thermal model.