Solution to filling time prediction issues for constant pressure driven injection in RTM

When producing a composite part with the Resin Transfer Molding process, resin is injected through a dry preform previously inserted in a closed mold, either using constant flow rate or constant pressure injection strategy. In the case of constant pressure injection, filling times are usually predicted by using the integral form of Darcy's law, but they are often off the reality. A solution is proposed here by considering that the flow rate expected during the process cannot always be provided by the injection unit. Moreover, the resistance to flow increases as the flow front advances, decreasing the injection flow rate and the effective injection pressure delivered by the injection system. The modeling of the entire system is proposed by updating the injection parameters at the mold inlet as the flow front advances. Results obtained from the developed code are compared to analytical results and validated with experimental injection data.