Analysis of a radial infusion model for in‐plane permeability measurements of fiber reinforcement in composite materials

Abstract

AbstractThe principal components of in‐plane permeability of fiber reinforcement during resin infusion can be determined by unidirectional or by radial flow experiments. Using unidirectional flow, two separate experiments are required to determine both components if the directions of principal axis are known. The main drawback of this method is related to the edge flow that may significantly affect the accuracy of measurements. In radial flow, both principal components can be determined by performing one experiment when the directions of principal axis are known. However, developed models that apply to this method require iterative procedures and are highly sensitive to the radius of the injection port. Measurements of the flow front displacement have to be taken when the wetted area becomes large enough in comparison with the size of the inlet gate. This analysis is based on a quasi‐steady radial infusion model developed by Adams et al., Int. J. Multiphase Flow, 14, 203 (1988), which is used for calculation of the principal components of in‐plane permeability. It is shown that the anisotropy coefficient and consequent permeability may be evaluated at any stage of the flow front displacement. This implies that the pressure difference does not necessarily need to be constant during the experiment, as usually required for most previous models. Asymptotic analysis for very small and very large flow front displacements is also conducted and comparison with point source algorithms is provided. Three accurate and relatively simple algorithms that do not require iterative procedures for evaluation of in‐plane components of permeability are proposed. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers