Directional Permeability Measurement of Deformed Reinforcement

Abstract

This paper presents a method for the evaluation of the anisotropic permeability of deformed woven fabrics. In order to conform to complex shapes, the woven fabric must undergo a certain amount of deformation. This deformation disturbed the resin flow and the filling of the mold cavity in liquid molding processes such as resin transfer molding (RTM). It is important for computer simulations of the filling process to predict the change of directional permeabilities k, and k₂ caused by the deformation of the fabrics. Several flow experiments were conducted on a nonstitched woven fabric with different deformation angles. The deformation affects the global permeability and the directional permeabilities k₁, k₂. At the same time, the principal permeability axes are shifted. The resulting permeability is related to the orientation of the fabric. This article presents characteristic permeability curves for the fabric JBMartin NCS 81053-A as a function of the shearing angle or, alternatively, of the resulting fiber fraction. It is possible to conclude that for the fabric tested, the shearing angle of the reinforcement will have a definite influence on the resin flow pattern.