A twinning study (Q795533)

Motivated by the phenomena of twinning, trilling, etc., the paper provides estimates of the invariance groups of crystals which have multi- valued constitutive functions (potentials). It gives a necessary and sufficient condition relating the invariance group to the number of branches of the constitutive function. An example is also considered which adapts the theory of ''stress-free joints'' of \textit{J. L. Ericksen} [ibid. 13, 3-15 (1983)] to the thermal expansion of a twinned crystal.