A Sensitivity-Based Gate Location Algorithm for Optimal Mold Filling During the Resin-Transfer Molding (RTM) Process

Report No. ARL-TR-2771
Authors: Roopesh Mathur, Suresh G. Advani, and Bruce K. Fink
Date/Pages: July 2002; 13 pages
Abstract: A sensitivity-based gate location algorithm for optimal filling of molds in the resin-transfer molding (RTM) process is described in this report. In the RTM process for composite manufacturing, a fiber preform is placed inside a mold and resin is injected into it under high pressures through inlets or gates. Finite-element-based resin-flow simulation codes have been successfully used for modeling and analysis of the process. This process is increasingly used for the manufacture of three-dimensional (3-D) composite parts with material and geometric complexities. In such cases, the locations of the gates cannot be determined easily except by expensive trial and error, both experimentally and computationally. Hence, systematic search methods working in tandem with flow simulations are necessary to determine gate locations for optimal filling. In this report, the governing equation for pressure along with the boundary conditions is differentiated with respect to the coordinates of each gate. The resulting system of pressure sensitivity fields is solved in parallel with the flow problem. The sensitivity fields are used to compute the gradients of the fill time with respect to the gate's coordinates. A standard gradient-based optimization algorithm is then used to determine the new coordinates of the gate location. This methodology of finding optimal gate locations for mold filling in RTM was demonstrated with a case study in which mold-filling time was minimized for the case of a single gate.
Distribution: Approved for public release
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Last Update / Reviewed: July 1, 2002