Three-dimensional evaluation of permeability of fiber reinforced composite materials based on their microstructures

This paper proposes a novel computational method for the evaluation of the permeability of fiber reinforced composite materials with complex microstructures. The homogenization theory for solid-fluid mixture is employed to characterize the micro-macro coupling effects. A characteristic function associated with the flow velocity is derived, whose average is defined as the permeability tensor. The derived relation between the macroscopic velocity and pressure gradient coincides with the conventional Darcy's law. Therefore, the proposed method enables us to predict the permeability tensor numerically without any experimental work. Furthermore, the characteristic function provides useful information to understand the correlation between the microscopic architecture and the macroscopic permeability tensor. Once the permeability tensor is given, we can use a conventional process simulator under the realistic process conditions. The macroscopic pressure gradient is obtained, which leads to the analysis of the actual microscopic flow field in the microstructure. The proposed microstructure-based evaluation can be used as the pre/post-processing of the conventional macroscopic process simulation. Three-dimensional modeling and analysis are shown for textile composites with the help of finite element method.