The Modeling of Pressure Distribution in Resin Transfer Molding

The resin transfer molding process (RTM) allows the production of large FRP parts. In this technique layers of reinforcements (mats, woven rovings) are inserted into the mold cavity and resin is injected to fill the closed mold. Cavity pressure distribution is the most important parameter to minimize leakage problem at the parting line, to reduce mold deformation and to assure a good quality part. In this paper, a simplified model applicable to unidirectional flow is proposed to predict that pressure. It is based on Darcy's law for flow of liquids through a porous media. The permeability of the reinforcement which is a function of the glass content and characteris tic of each type of reinforcement, mat or woven roving, is evaluated. Effects on the model of parameters such as glass density, surface density of the reinforcement and number of reinforcing layers are examined. The mold and instrumentation used to collect data are described and preliminary results are presented for reinforcing mat.