Liquid Composite Molding (LCM) constitutes an important set of technologies for manufacturing polymer composites that include processes such as Resin Transfer Molding (RTM), Vacuum-Assisted Resin Transfer Molding (VARTM), etc. Several simulations of the LCM mold-filling processes have been developed by companies and academic institutions to reduce the LCM mold-design time.
There have been several studies/simulations involving sink effect as well as void formation in dual-scale fabrics that required modeling of microscopic flows in tows using Darcy’s law, which in turn required estimating the tow permeability. Researchers have used theoretical models, such as the Gebart’s model, for this purpose which often assume that the fibers are arranged parallel to each other in perfect square or hexagonal arrays. However, what is surprising is that despite being used so widely over last several decades, these models have never been tested for their accuracy by comparing their predictions with the permeability measured at the tow level using experiments.
In the current investigation, the permeability of glass-fiber tow at three different fiber-volumefractions (60%, 55%, 50%) have been obtained by using different methods. The permeability of such porous media is determined by: a) an experimental method adapted for such tow-scale systems, b) theoretical models available in literature, and c) numerical simulations based on solving Stokes flow and Whitaker’s closure formulation equations. The results derived from all these methods have been compared to find the degree of accuracy and agreement among them.