Evolution of fibre waviness during the forming of aligned fibre/thermoplastic composites

A model for the in-plane deflections of a system of discrete axially loaded fibres in a viscous matrix has been developed to study the evolution of fibre waviness during forming of aligned thermoplastic composites. A simplified numerical solution approach to the theoretical model is implemented, allowing for the analysis of a large number of fibres with a reasonable computational effort. The results of the model show the maximum fibre deflections to be consistent with the linearized beam-column theory used in the model development, but that the time predicted to attain the maximum deflections is comparable to typical forming times. Non-uniform fibre loadings are modelled and the resulting distributions of fibre deflections are analysed. The interactions between neighbouring plies and between neighbouring fibres within a single ply are found to have significant effects on the distributions of fibre deflections and on the response times of the system.