The use of substitution groups to derive thermodynamical relations between the material constants of piezoelectric materials

It is shown how substitution groups can be used to derive relations between the material constants of an anisotropic homogeneous piezoelectric medium. The structure of these relations is explained by means of a general record and independent systems are found, the existence of which has a clear physical interpretation. The concept of substitution group is generalized and some important thermodynamic substitution groups are derived; the method can be applied without substantial changes to an arbitrary type of anisotropic homogeneous medium.