Analytical modelling of the behaviour and scatter of the flexural modulus of randomly oriented carbon fibre strand thermoplastic composites

Randomly oriented strand composites are promising materials for complex-shaped parts, especially in the aerospace and automotive industries. However, test data from small specimens tend to have a high level of scatter as these materials contain several centimetres of chopped carbon fibre strands. In this study, we investigated the mechanical properties of ultra-thin chopped carbon fibre tape reinforced thermoplastics (UT-CTT), which contain chopped thermoplastic thin-ply prepreg tapes produced using a paper-making technique. We propose a model for accurately evaluating the flexural modulus and its scatter, which was verified by comparison with experimental data. The predictions of the model showed excellent agreement with the experimental results. This method makes it possible to quantify the scatter of the flexural modulus and is useful for designing geometries of, not only standard test specimens, but also complex parts for actual applications.