Desirable features in mold filling simulations for liquid composite molding processes

Numerical simulations of the mold filling process in various Liquid Composite Molding (LCM) techniques, in which the fiber reinforcements represent the porous media and the polymeric resin is the impregnating fluid, have been successfully utilized for over a decade now, but they continue to be under dynamic development. Some of the recent applications are the increased emphasis on design optimization, control of the impregnation process and the rapid introduction of new LCM techniques such as the Vacuum Assisted Resin Transfer Molding (VARTM). This paper describes the requirements that these new applications demand on the implementation of such numerical simulation for modeling mold filling in LCM processes, namely Resin Transfer molding (RTM) and VARTM. Liquid Injection Molding Simulation (LIMS) developed at the University of Delaware, which can simulate the flow in such processes, has been modified to encompass these features. It addresses practical issues concerning modeling the part geometry, such as the proper choice of one-, two- and three-dimensional elements and their effective combinations. It also describes the simulation of non-trivial boundary conditions, placement of sensors and allowing for resin injection control using the functions built into the simulation program and the embedded scripting language. Several examples are presented to highlight the importance of its flexibility. The paper also addresses some VARTM specific issues, such as the modeling of distribution media, dimensional change during filling and fiber tow saturation. (C) 2004 Society of Plastics Engineers.