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.

A Review of Thermoplastic Resin Transfer Molding: Process Modeling and Simulation

“…Few recent studies focus on coupling thermo-chemo-mechanical simulations with the flow simulation of reactive thermoset [100,101,102,103,104] and thermoplastic [99,105,106] RTM processes. Imbert et al [102,103] modeled the RTM process considering the thermo-chemo-mechanical aspects in the flow of reactive thermoset resin mixed on-line in a dual-scale porous medium. The simulations were performed in PAM-RTM TM software.…”

Introduction of intra-tow release/storage mechanisms in reactive dual-scale flow numerical simulations

“…For the further developments in this paper, the choice is made to use the first order approximation of the time derivative of the advection equations to simulate the discoloration and later the reactive problem (details on the technique are given in Imbert et al. 7 ). For the discoloration simulation (the tracked quantity of interest is C ), the first order approximation of the time derivative allows expressing SCSat ConvCT and SCSat ConvTC for the new time step n + 1 ( n being the current time step) in a discrete manner for each element of the saturated area (equations (10) and (11)) …”

“…7 In these articles, the channels and the tows of the microstructure are treated separately and the evolutions of the quantities of interest in these two regions are linked through sink/source terms. In these three articles, 7,14,17 after the saturation, resin is considered permanently stored in the tows. Thus, the physics considered in the simulation models proposed in the literature are summarized in Figure 1.…”

Study of Compaction Properties and Permeability Prediction of Multilayered Quadriaxial Non-Crimp Fabric in Liquid Composite Molding Process

“…The resin impregnation process is driven by an injection pressure and the solid composites formed after the resin cures. The process of the liquid resin flowing through fibrous reinforcements is described by Darcy's law (Equation (1)), which states a dependence of the flow velocity on the permeability of the medium, viscosity of the liquid and the applied pressure gradient [1][2][3][4].…”

“…The resin impregnation process is driven by an injection pressure and the solid composites formed after the resin cures. The process of the liquid resin flowing through fibrous reinforcements is described by Darcy’s law (Equation (1)), which states a dependence of the flow velocity on the permeability of the medium, viscosity of the liquid and the applied pressure gradient [ 1 , 2 , 3 , 4 ]. where v , µ , ∇ P and K are the volume averaged velocity, the dynamic fluid viscosity, the pressure gradient across the porous medium and the permeability, respectively.…”