Novelties in Rotational Hardening

Constitutive relationships for soils including anisotropy are, nowadays, quite common and, in some cases, implemented in numerical codes. These are usually elastic–plastic models characterized by anisotropic strain hardening. They very often enable both yield function and plastic potential to pseudorotate about their pseudoaxes in the effective stress space. Many strategies have been suggested to describe such an evolution, but, independently of the rule chosen, they all introduce, as a side effect, parasite distortions of surfaces. Only very recently, the authors introduced a rigorous approach to describe a pure rotational hardening. In the light of that work, in this paper, the authors reconsider a series of approaches introduced in the literature; they critically discuss them, in both triaxial and deviatoric planes, also presenting as evidence the consequences of the anisometry of the triaxial plane with respect to the effective stress space.