NUMERICAL-ANALYSIS OF THE RESIN TRANSFER MOLDING PROCESS BY THE FINITE-ELEMENT METHOD

As large components of fiber reinforced composite materials are being more frequently produced by Resin Transfer Molding (RTM), a computer s imulation of the injection process can help the mold designer to accom plish three important tasks: (1) to ensure a complete filling of the m old through adequate positioning of the injection ports and of the air vents; (2) to verify the integrity of the mold during the filling pro cess through knowledge of the pressure distribution; and (3) to optimi ze the production cycle using information about the filling time. The resin impregnation is usually modeled as a flow through a porous mediu m. It is governed by Darcy's law, which states that the flow rate is p roportional to the pressure gradient. In our model, Darcy equation is solved at each time step inside the saturated part of the mold using n onconforming finite elements. This method was chosen because the appro ximated flow rates, contrary to conforming finite elements, satisfy lo cally the important physical condition of resin conservation across in ter-element boundaries. This permits simplification of the numerical p rocedure. It is no longer necessary to resort to a control volume appr oach to move the flow front forward. The resin pressure distribution a nd the resin front positions are obtained by the computer simulation a nd calculated results for selected mold geometries are compared with e xperimental observations. Molds with inserts, multiple injection ports , and the case of anisotropic preforms can be analyzed by the computer program. (C) 1993 John Wiley & Sons, Inc.