A review on theoretical modelling for shearing viscosities of continuous fibre-reinforced polymer composites

Optimisation design of composite structures required an accurate predictive model for forming behaviour. The simulation process contains a number of model parameters which include transverse and longitudinal viscosities of continuous fibre-reinforced viscous composites, fundamental to predicting the shear rheology. These two shearing viscosities are defined by the viscosity tensor where transverse and longitudinal viscosities are respectively the shearing resistance for the unidirectional composite across and along the fibre direction. This paper reviews previous work on modelling techniques, which would offer some insight in development of a fully predictive physical model so as to eliminate any time-consuming experimental characterisation. It is suggested that neglect of non-Newtonian effects, viscoelastic effects (fibre elastic deformation), and fibre rearrangement during shearing could be the main reason for the existing models underestimating test data. Recommendations for future work are made.