Three-Dimensional Resin Transfer Molding Process: Developments for Thick Composite Manufacturing Applications.

The Resin Transfer Molding RTM process has been increasingly used in the manufacture of large reinforced composite components, and the current trend is towards manufacturing of thick composites and thick composite sections with impermeable inserts. Current practices involved in the computer simulation of RTM resin impregnation are restricted to two-dimensional formulations based on Darcys law for flow through thin cavities. The multiple fiber layers in thick composites, and the presence of impermeable inserts inside the fiber bundles, make the resin impregnation a three-dimensional flow, and a better understanding of the resin impregnation can be achieved by considering a fully three-dimensional model. In this paper, a fully three-dimensional simulation of resin impregnation in a porous fiber media based on Darcys law is considered. The developments are based on a Finite Element-Finite Volume FEFV technique in which the pressure field is solved using the finite element method and the saturated regions of the resin are determined based on conservation of mass. The technique permits an accurate tracking of the resin impregnated fronts involving multiple gates, inserts, and the like. The computational tool will be effective in design of better molds with optimum location of injection ports, vents, and forms a basis for process cycle optimization with a knowledge of mold filling time, fill pattern, and the pressure histories. Simulations involving multiple injection ports, impermeable inserts inside the mold and the flow around them, and airgaps can be effectively handled and are demonstrated.