restriction on elastic moduli

To modeling the auxetic materials: some fundamental aspects

The auxetic materials are considered from the point of view of correspondence to the classical theory of elasticity. It is shown that some classical postulates relative to the elastic constants should be refined. Three cases of description of auxetic materials — by the model of linear elastic isotropic body, by the model of linear elastic transversally isotropic body, by the nonlinear elastic isotropic body (Murnaghan potential) — are analyzed shortly.