Heuristic algorithm for determining optimal gate and vent locations for RTM process design

In the resin transfer molding (RTM) process, locations of gates and vents are important design parameters that have a great impact on the resin flow pattern and mold filling time. The resin flow pattern is crucial to the quality and properties of the final product. A good resin flow pattern can cover all dry areas in the mold with liquid resin; whereas, a poor flow pattern will lead to some dry spots, which directly result in defects. In this paper, a single gate, multiple vents location problem for 2-D RTM process design is formulated as an optimization model. A process performance index is introduced as the objective function to evaluate the flow pattern in a 2-D RTM process. The authors introduce the concept of general distance between any two locations within the mold. To avoid forming dry spots during the process, all potential vents are determined once a gate is given. A two-phase optimization method, called a graph-based two-phase heuristic (GTPH), is used to find the appropriate locations of the gate and associated vents. The results are compared with those from other methods such as genetic algorithms.