The effect of aspect ratio of inclusions on the elastic properties of unidirectionally aligned composites

This paper examines the influence of aspect ratio α, from zero to infinity, on the effective elastic moduli of a transversely isotropic composite. The reinforcing inclusions, which could be flakes or short fibers, are assumed to be spheroidal and unidirectionally aligned. Of the five independent elastic constants, the longitudinal Young's modulus E₁₁ and in-plane shear modulus μ₁₂ appear to increase with increasing aspect ratio, while the transverse Young's modulus E₂₂, out-plane shear modulus μ₂₃, and plane-strain bulk modulus K₂₃, generally decrease. It is further noted that E₁₁ is more sensitive to α when α > 1 but the others are more so when α < 1. The present analysis was carried out by the combination of Eshelby's and Mori-Tanaka's theories of inclusions.