Effective Electromagnetic Properties of Woven Fiber Composites for Shielding Applications

Composite materials reinforced with woven conductive fibers can be good candidates for electromagnetic shielding applications. Their light weight provides an important advantage over metallic alloys classically used in the automotive and aircraft industries. However, numerical modeling of composite-based large-scale structures, such as shielding enclosures, is rendered almost impossible by the heterogeneities at the microscopic scale. This problem is commonly addressed using electromagnetic homogenization methods. In this paper, we propose a homogenization technique based on finite element computations and inverse problem solving for estimating the effective properties of woven composites. The effect of electrical contacts between the fibers is also studied and its influence on the global behavior of the material is analyzed. The results are then shown to diverge from those obtained using analytical mixing rules over the frequency range of 1-40 GHz. Thus the suitability of these homogenization methods is discussed with respect to the studied frequency range and the nature of the microstructure.