Electromagnetic Modeling of Composites Reinforced by Randomly Distributed Fibers

Fibers serving as reinforcements are randomly distributed within an epoxy matrix to enhance the mechanical performance of composites. The fibers’ volume fraction and spatial randomness also significantly impact the electromagnetic (EM) properties. However, accurately predicting such effects poses considerable computational challenges while relating to micro-scale fibers. This paper proposes a computationally efficient method for analyzing the EM scattering property of composites reinforced by randomly distributed micro-fibers. A single layer composite with unidirectional fiber orientation is treated as 2D periodic in longitudinal directions. A volume unit containing randomly distributed fibers is periodically repeated to approximate the full composite structure. In order to generate randomness, the volume unit is divided into a large number of very small volume sections. Each section is randomly filled with either fiber or epoxy material. The material along <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i>-direction remains uniform within each section. This allows the volume sections with the same z-depth to be treated as a single layer to apply the Fourier modal method. A single layer with unidirectional fiber orientation will be divided into hundreds and thousands of small sub-layers. Each sub-layer is composed of many small volume sections. Multilayer composites with fibers in different layers oriented in different directions can be treated layer by layer from top to bottom. Reflection and transmission coefficients are obtained with the scattering matrix method. Numerical investigations are carried out. This model is validated by commercial software. The scattering properties of composites with different randomness and fiber volume fractions are investigated.