Elastic anisotropy in heterogeneous materials

Abstract

Heterogeneous materials exhibit anisotropy induced by factors such as individual phase properties and microstructural configuration that form crucial descriptors of heterogeneity. A review of anisotropy indices proposed in the context of single crystals and composite materials reveals their limitations in quantifying anisotropy in heterogeneous materials. To address this shortcoming, this work presents an approach to quantify elastic anisotropy in heterogeneous materials utilizing their effective elastic properties thereby embodying the effects of heterogeneity. Anisotropy quantification has been demonstrated considering two-phase composite materials highlighting the phenomenon of heterogeneity driven anisotropy and emphasizing the crucial role of constituent volume fractions, reinforcement shape and elastic contrast in influencing the extent of anisotropy. The proposed approach has been extended to quantify anisotropy arising from defects such as porosity and cracks in homogeneous media. Additionally, specific material and microstructural descriptors leading to overall isotropy in composite, porous and cracked materials have been validated. The presented results demonstrate the applicability of the presented anisotropy quantification approach to any class of heterogeneous materials.