Keywords: liquid composite molding, resin infusion, impregnation, finite volumes, resin reaction, viscosity.

In recent years, thermosetting matrix composite materials have been widely used for several applications in different fields, such as automotive, aerospace, aeronautical, nautical, energy and sporting goods. The demand for high performance and constant quality, combined with the need to reduce costs due manufacturing inefficiency, resulted in an increasing use and development of industrial manufacturing processes, characterized by low human intervention, above all during the reinforcing preform impregnation. The reduction of the human presence is also strongly desired to avoid health diseases caused by the emission of volatiles during the resin reaction.

Taking into account the above considerations, much interest has been focused on the liquid composite molding (LCM) processes, such as RTM, VARTM, RIFT, RFI, SCRIMP, characterized by the impregnation of a dry fibrous perform, opportunely placed between solid-solid or solid-flexible dies, by the means of injection or infusion of the catalyzed resin.

The opportune planning of LCM processes is, however, very complex, being the process characterized by non-stationary multiphase flows in a three dimensional porous domain with anisotropic permeability, by the cure reaction, influencing the temperature, the degree of cure, and the viscosity of the processing resin, and by the elastic deformation of the fibre bundle due to the applied pressure.

Non optimal process planning can lead to non-uniform preform compaction, variations of product thickness and volume fractions of matrix and reinforcement, and finally into incomplete preform filling. Nowadays, computational techniques are more and more considered as effective tools for process analysis and optimization, instead of time and cost expensive trial and error procedures, in particular to define the positions of inlets and outlets, the working temperature and pressure, and the timing of each step.

In this paper a finite volume model, based on the solution of continuity, momentum and energy equations, has been proposed for the simulation of the impregnation stage in a LCM process. Numerical data provided by one dimensional flow simulations are in excellent agreement with the well known analytical closed form solution. The influence of the resin cure reaction on the impregnation process has also been investigated. In particular, it has been found that in the very beginning of the impregnation stage, the contrasting influences of temperature and degree of cure variations on resin viscosity compensate each other; however, as the cure reaction proceeds, the processing resin viscosity variation is not negligible, suggesting the relevance of a proper consideration of the cure reaction into the resin flow models.

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