Simulation and experimental validation of the effect of material and processing parameters on the injection stage of compression resin transfer molding

Abstract

The effects of gap thickness, injection flow rate, overflow percentage, initial fiber content, and resin viscosity on the resin distribution at the end of the injection stage of compression resin transfer molding have been studied. Experimental results have shown that in all the cases, a certain amount of resin penetrates the preform, contrary to the extended hypothesis that the resin flows exclusively through the gap. Furthermore, resin distribution is not homogeneous and the penetration depth varies depending on the distance from the injection point, being deeper near the inlet point. Simulation results based on the quantitative analysis of the amount of resin penetrating into the preform demonstrates that the most influent parameters are the initial fiber content, the gap percentage and the overflow percentage. In fact, the ratio between the permeability of the gap and the preform (r) governs the tendency of the resin to flow through the gap or to penetrate into the preform. Increasing r reduces the amount of resin which penetrates into the preform, but there is an upper asymptotic limit from which no differences are noted. Finally, simulation results have also demonstrated that the preform compression can be neglected during the injection stage, as the pressure into the preform is low.