Efficient dual-scale flow and thermo-chemo-rheological coupling simulation during on-line mixing resin transfer molding process

Abstract

Simulation tools are required to ease the determination of the optimal process parameters and injection strategy of short cycle resin transfer molding (RTM). The developed finite element method/volume of fluid numerical tool aims to simulate accurately and efficiently the flow of a reactive resin mixed on-line in a dual-scale porous reinforcement during the resin transfer molding process. A macroscopic mesh deals with the flow inside of the channels of the reinforcement while a representative microstructure associated to each element allows reproducing both the unsaturated area and the intra-tow resin storage. Degree of cure, temperature, and viscosity are updated and transported at each time step, both in the channels and in the tows of the fabric using advection equations and sink and source terms for inter-scale exchanges. A new flexible approach based on the textile’s geometry defines automatically the representative microstructure associated to each macroscopic element depending on its size and shape. Additionally, tow saturation is simplified under the assumption of high-speed injection to a sum of one-dimensional transverse tow saturation problems, which reduces the computational cost of the simulation. Convergence tests have highlighted the ability for the simulation tool to treat with an equivalent degree of accuracy a saturation problem with elements exhibiting element sizes three times smaller to three times bigger than the length of the unsaturated area. Significant computation time reductions have also been noticed when large elements were used. Finally thermo-chemo-rheological coupled simulations have been conducted, highlighting the importance of taking the dual-scale effect into account when simulating reactive injections with on-line mixing.