The theory of materially uniform but inhomogeneous bodies presented by Noll [26] and expanded by Wang
[33] starts with the notion of the material isomorphism. A material isomorphism is a linear transformation
between the tangent space of two distinct material points that leaves the energy invariant. By energy here, the
stored energy function is meant, which is a measure of the response of the body to applied loads. If for every
pair of material points, a material isomorphism exists; then, this construct is called material uniformity, and
the body is called materially uniform. From the physical point of view, different points of a materially uniform
body are mechanically indistinguishable. This framework has attracted some attention over the years. Contact
with the theory of material forces is described in Epstein and Maugin [11], extension to Cosserat continua in
Epstein and deLeon [9] as well as second gradient theories [7,24] among other areas. A recent monograph by
Epstein and Elzanowksi [10] describes in a thorough and apt way this theory while giving variable extensions
and applications. Our approach on the topic can be seen in Sfyris [27–31], Sfyris et al. [32]