Mathematical model of stress formation during vacuum resin infusion process

Composite material manufacturing technology based on vacuum infusion which is also known as resin film infusion technology, utilises a vacuum bag to d ebulk or compact parts of complete laminate. After debulking the resin is a llowed 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 heterogene ity can be formed in the laminae. The objective of this article is to devel op a mathematical model of the stress and heterogeneity formation during th e resin film infusion process. A heuristic model which considers the viscou s flow through the porous reinforcement is developed and it allows an under standing of the influence of different process parameters on the pressure d istribution 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 liqu id 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-Newtoni an viscous liquid. The results obtained allow the simulation of complex man ufacturing process to be carried out. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.