Processing of thermoset prepregs for high-volume applications and their numerical analysis using superimposed finite elements

Prepreg compression moulding (PCM) potentially fulfils the requirements for high-volume applications of structural thermoset composites. Preforming of thermoset prepregs is a first step in PCM followed by consolidation and curing. High volume manufacturing necessitates automation of the preforming stage in order to achieve the required production rate and repeatability. The present work investigates the processing of thermoset prepregs based on in-plane shear characterisation tests along with preforming experiments using classical hemispherical dome tests. The second part of this work proposes a simplified numerical scheme for prepreg preforming analysis using superimposed finite elements. The elements share common nodes. One of the sets of elements is assigned with the bi-directional material data of fibrous reinforcement. The second set of elements is allocated to resin behaviour. The scheme has the advantages of defining controlled fibre-to-resin ratio and predicting the stress field within individual constituents in the subsequent structural analysis. Although the deformation behaviour of structural prepregs is largely driven by fibrous reinforcement, however, it has been observed here that the resin contributes to alter the shear rigidity of the material which eventually affects the shaping behaviour of the deformed prepreg. It has also been shown that the proposed numerical approach is capable of predicting the deformation behaviour of the prepreg.