Microscale permeability predictions of porous fibrous media

A good understanding of woven fiber preform permeabilities is critical in t he design and optimization of the composite molding processes encountered i n resin transfer molding (RTM); yet these issues remain unresolved in the l iterature. Many have attempted to address permeability predictions for flat undeformed fiber preform, but few have investigated permeability variation s for complex geometries of porous fibrous media. In this study, the object ives are to: (i) provide a brief review of existing methods for the predict ion of the fiber mat permeability; (ii) postulate a more realistic represen tation of a unit cell to account for such fabric structures as crimp, tow s pacing and the like; and (iii) apply computational approximations to predic t effective permeabilities For use in modeling of structural composites man ufacturing processes. The Stokes equation is used to model the flow in the inter-tow region of the unit cell, and in the intra-tow region, the Brinkma n's equation is used. Initial permeability calculations are performed for a three-dimensional unit cell model representative of the PET-61 woven fabri c composite. The results show good agreement with experimental data publish ed in the literature. (C) 2001 Published by Elsevier Science Ltd.