Optimization of gate and vent locations for resin infusion processes using genetic algorithms

In composite manufacturing processes, such as resin transfer molding (RTM) and vacuum assisted RTM, the resin is infused into a mold containing a preform. The liquid injection molding simulation, which was developed at the University of Delaware, is capable of simulating the movement of the resin flow fronts through a fiber preform, when the gate and vent locations are specified. When two flow fronts meet and trap air between them, a resin-starved area, called a 'dry spot', is formed, causing a structural weakness in the final composite part. This problem can be solved by the optimal placement of gates and vents. In order to determine optimal gate and vent locations, a genetic algorithm has been used as a search tool. The objective function for the optimization is expressed as a process performance index (PPI) and incorporates the fill time and dry spot formation. The PPI is at a minimum at the optimum gate and vent(s) configuration. We demonstrate the method through a case study.