Optimization of the Resin Transfer Molding Process to Manufacture Semi-Rigid Boats With Composites Applying Computational Fluid Dynamics Simulation and Novel Analytical Approaches

Abstract Resin Transfer Molding (RTM) is a low-pressure closed molding process that produces dimensionally accurate products with a high-quality surface finish. Successful implementation of the molding process requires accounting for interdependent factors such as the viscosity of the resin, injection pressure, volume fraction of fibers, permeability, and process temperature. Analytical and numerical approaches reduce the risk of costly mistakes during the molding process and allow the comparison of different molding strategies. This work investigates productivity and quality in the manufacture of large composite parts intended for the marine sector. The aim is to propose an analytical and numerical methodology based on Computational Fluid Dynamics (CFD) simulations, supported by Ansys Fluent®, to select the best conditions for the polyester RTM process, considering both technical-operational and economic factors. Various setup options, inspired by other industrial success stories, are proposed to optimize filling time and the resin flow paths. The main general conclusions from the research are that resin injection into the periphery of the mold achieves the best filling results and that a longitudinal and transverse injection model (“fishbone” type) allows for relatively fast and controlled filling. It has been confirmed that “Peripheral” and “Fishbone” configurations are the most suitable for the RTM infusion process. Finally, a resin with longer polymerization times would also allow the use of the “Central Channels x18” model with excellent results.