Numerical characterization of material elastic properties for random fiber composites

This paper presents a numerical investigation of the material elastic properties for short-length mostly in-plane random fiber composites, based on microscale geometrical modeling. The particular case considered is that of materials in which the majority of fibers' orientations are contained or slightly deviate from a dominant plane. Representative volume elements for two types of random fiber composite material geometries with different fiber aspect ratios and volume fractions are generated using a novel technique. The elastic properties of the equivalent homogeneous material are determined using direct three-dimensional finite element analysis. A windowing-type analysis is employed to investigate the influence of the fiber distribution homogeneity on the homogenized elastic properties. The results are compared and validated using two alternative approaches - first, by orientation averaging of the stiffness tensor of the equivalent unidirectional composite determined by direct FEM analysis and, second, by employing the laminated random strand method.