Composite material manufacturing technology based on vacuum infusion which is also known as resin film infusion technology, utilises a vacuum bag to debulk or compact parts of complete laminate. After debulking the resin is allowed to be infused by the vacuum to completely wet-out the reinforcements and eliminate air voids in the laminate structure. The resin infusion can also develop stresses in the fibres. Further, different types of heterogeneity can be formed in the laminae. The objective of this article is to develop a mathematical model of the stress and heterogeneity formation during the resin film infusion process. A heuristic model which considers the viscous flow through the porous reinforcement is developed and it allows an understanding of the influence of different process parameters on the pressure distribution in the infused resin. The reinforcement permeability tensor is defined by the Carman-Kozeny equation and depends on average pore size and specific pore concentration. The use of a non-linear equation of filtration allows for a definition of the pressure distribution inside a viscous liquid resin dependant on the external flux. The fibres which form the preform are assumed as being the pure elastic bodies and the resin as a non-Newtonian viscous liquid. The results obtained allow the simulation of complex manufacturing process to be carried out.