Constitutive relations for isotropic materials allowing quasi-linear approximation of the deformation law

© 2019 Published under licence by IOP Publishing Ltd. Variants of deformation potentials for isotropic materials that do not obey the "single curve" hypothesis are considered. The advantage of the potentials formulated in two normalized stress spaces in comparison with other variants of quasi-linear models of the constitutive relations for isotropic materials is demonstrated. It is shown that the claims of some authors on the originality and universality of the deformation potentials proposed by them are not justified, and their variants of relations are reduced to two forms of writing in normalized spaces