In Resin Transfer Moulding (RTM), usually a thermoset resin is injected into a closed mould cavity containing a dry fibre reinforcement fabric to manufacture Fibre Reinforced Plastics (FRP). The resin must infiltrate all the spaces unoccupied by the reinforcement to ensure a defect-free composite. As one cannot observe within a closed mould cavity, over the last three decades, numerical models and simulations of resin flow have been developed to improve the manufacturing process. This work reviews the models of important phenomena and complex flow physics occurring at both the macro and micro scales during resin impregnation into fibre reinforcements, as well as their numerical implementation. For accurate predictions, reliable inputs such as fabric permeability and resin viscosity are crucial; therefore, permeability characterisation and viscosity variation are also briefly addressed. The focus is on the development of computational models and their sub-components, which include resin flow front calculation, replicating the reinforcement dual-scale nature, implementing the viscosity and permeability variations, and capillary effects. Previous reviews and research that have advanced the micro and macroscale RTM modelling have been summarised. The role of such simulations for optimisation, control, and automation of the process has been discussed along with possible future directions of research.
Rajinth et al. (2026) studied this question.