  Heterogeneous materials exhibit anisotropy to varying extent that is
influenced by factors such as individual phase properties and microstructural
configuration. A review of the existing anisotropy measures proposed in the
context of single crystals reveal that they do not account for the material and
microstructural descriptors influencing the extent of anisotropy in
heterogeneous materials. To overcome this limitation, existing anisotropy
indices have been re-interpreted by considering the effective elastic
properties of heterogeneous materials obtained by appropriate homogenization
techniques. Anisotropy quantification has been demonstrated considering two
phase composite materials highlighting the role of constituent volume
fractions, secondary phase shape and elastic contrast in influencing the extent
of anisotropy. Specific cases leading to overall isotropy in two phase
composite materials and extension of the approach to consider porosity and
cracks have also been presented demonstrating the applicability of the approach
to any class of heterogeneous materials thus filling a crucial gap in the
existing literature.
