Elastic anisotropy in heterogeneous materials

Heterogeneous materials exhibit anisotropy which is influenced 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 reveals that they do not account for the descriptors of heterogeneity limiting their utility in heterogeneous materials. To address this shortcoming, this work presents a novel approach to quantify elastic anisotropy in heterogeneous materials utilizing their effective elastic properties. Anisotropy quantification has been demonstrated considering two phase composite materials highlighting the crucial role of constituent volume fractions, secondary phase shape, and elastic contrast in influencing the extent of anisotropy. Additionally, specific material and microstructural descriptors leading to overall isotropy in composite materials are validated and an extension of the approach to account for defects such as porosity and cracks is presented. The presented results demonstrate the applicability of the anisotropy quantification approach to any configuration of heterogeneous materials.