Homogenization of Metal Grid Reinforced Composites for Near-Field Low Frequency Magnetic Shielding

Abstract

The purpose of this paper is to provide simple analytical homogenization methods for composite materials containing a metallic wire grid. Estimating their effective electrical properties facilitates the numerical simulation of composite structures for shielding applications in the automotive industry. The presented methods are based on surface impedance approaches and effective media theory. The obtained results show that the shielding properties of the described wire grid composites can be accurately estimated and bounded, using the proposed theories in the low frequency range. The frequency limits vary according to the studied sample. For the presented materials, the validity of the results is shown to be up to a few megahertz. The experimental validation is done by measuring the shielding effectiveness of composite samples using a near-field test bench.

Homogenization of woven composites for shielding applications: the case of oblique incidence

“…The studied material (Figure 4) is a fiber-reinforced composite formed by combining a dielectric matrix and woven conductive fibers. These woven fibers can be made of conductive metals to which an epoxy resin is added according to a sheet molding compound manufacturing process [7]. Otherwise, each strand of fiber is formed by grouping, on the microscopic scale, a number of individual fibers thus forming a bundle of fibers [1].…”

“…This flexibility in fiber design has a direct influence on the shielding properties of the manufactured composite. On the other hand, greater shielding effectiveness values can be obtained if metallic fibers are used [7]. In this case, fully conductive fibers made from copper or steel provide the resulting composite with even higher levels of shielding.…”

Comparative Study of Thin Layers Modeling in Electromagnetism: Application to Multilayer Magnetic Shielding

“…Several homogenization techniques have been developed to predict the effective electromagnetic properties of composite materials. These techniques include analytical, numerical, and experimental models [12][13][14][15][16][17]. Achkar et al [12] introduced a homogenization method that relies on finite element computations and inverse problem solving to estimate the effective properties of woven composites, but it was restricted to high frequencies (f > 0.1 GHz) where only electrical conductivity and dielectric permittivity are unknown parameters.…”

“…Therefore, the conductivity resulting from the proposed method may not be very accurate for high frequency fields. In [16], an analytical homogenization method based on surface impedance and effective media theory for composite materials containing metallic wire grid has been proposed. This work was limited to low volume fractions of inclusions.…”