Optimization of filling process in RTM using a genetic algorithm and experimental design method

In the resin transfer molding (RTM) process, preplaced fiber mat is set up in a mold and thermoset resin is injected into the mold. An important issue in RTM processing is minimizing the cycle time without sacrificing part quality or increasing the cost. In this study, a numerical simulation and optimization process for the filling stage was conducted in order to determine the optimum gate locations. The control volume finite element method (CVFEM), modeled as a 2-dimensional flow, was used in this numerical analysis along with the coordinate transformation method to analyze a complex 3-dimensional structure. Experiments were performed to monitor the flow front to validate the simulation results. The results of the numerical simulation corresponded with that of the experimental quite well for every single, simultaneous, and sequential injection procedure. The optimization analysis for the sequential injection procedure was performed to minimize fill time. The complex geometry of an automobile bumper core was chosen. A genetic algorithm was used to determine the optimum gate locations in the 3-step sequential injection case. Taguchi's experimental design method was also used for determining the pressure contribution of each gate. These results could provide the information on the optimum gate locations and injection pressure in each injection step and predict the filling time and flow front.