Session: 8.2 - Fluid Machinery

Paper Number: 158478

158478 - 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, which offers a dimensionally accurate and good surface finish product. Decision-making for the implementation of the infusion process requires considering factors that are highly correlated with each other. Fundamentally, the viscosity of the resin, the injection pressure, the volume fraction of the fibers, permeability, and process temperature. When the variables are so complex in an industrial environment, it is usual to find the ideal conditions through a “trial-error-correction” cycle. To reduce the high costs that this way of proceeding entails, initial conditions based on a prediction model are used.

In addition, the RTM process exhibits a series of important limitations related to cycle time and mold filling technique. On the other hand, ensuring the quality of the final product, especially in large-sized parts, is a great challenge. Therefore, it is interesting to use analytical and simulation techniques to carry out preliminary studies with the aim of reducing costs derived from trial-and-error experimental tests.

This work arises from the need to investigate productivity and quality in the manufacture of large-sized composite parts (in the order of 10-15 m) destined for the nautical sector. To this end, the objective is to propose an analytical and numerical methodology based on CFD simulation supported by Ansys Fluent ® to select the best conditions for the polyester RTM process considering technical-operational and economic factors. The theoretical basis presented has been formulated for its computational resolution using the Fluid Volume Method (FVM) selected according to previous studies as very suitable for discretizing and solving the equations for an RTM process. The main influencing parameter chosen is the variation in the volume fraction of the resin during the injection time (resin advance front). Different options are proposed based on other industrial success stories, seeking to optimize filling time and the resin path.

The chosen resolution algorithm has been simple. The algorithm iteratively solves the pressure and velocity fields starting from an initial set pressure and based on certain convergence criteria.

This analysis has allowed us to optimize the manufacturing strategy, as well as the mold filling times (versus the resin curing time) and to limit possible risks and other operational issues. The main general conclusions drawn 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. Likewise, it has been shown that “Peripheral” and “Fishbone” configurations are the most suitable proposals for the RTM infusion process. Finally, it has been possible to verify that a resin with longer polymerization times would also allow the use of the “Central Channels x18” type model with excellent results.

Presenting Author: Paul Bosauder Sequence Engineering Ltd

Presenting Author Biography: Paul has 24 years of experience specialising in computational fluid dynamics (CFD) and non-linear finite element analysis (FEA). Paul brings well over two decades of CFD and FEA simulation experience. He is a NAFEMS registered Professional Simulation Engineer (PSE) with advanced accreditation for both flow and stress analysis. Paul also holds a current CPEng (Mech) registration with the practice area description (PAD) of computer-based flow and stress analysis for the design, code verification, and fitness for service (FFS) assessment of industrial and process plant and equipment.

Paul provides leading-edge delivery of CFD and FEA consulting services to customers around the globe. He brings significant experience from a wide range of industries, problem types, and analysis tools to each project he delivers or supervises. In addition to the practical application of numerical simulation, Paul has authored and presented professional education short courses, led business development for new technology fields, and maintained front-line technical support of advanced engineering analysis software.