Shear and objective stress rates in hypoplasticity

This paper addresses some questions referring to shear within the context of hypoplasticity and the importance of objective stress rates in constitutive modelling. A short introduction to the stress changes due to rotations is followed by a discussion of the merits of the individual objective stress rates. It is shown that many of them differ only by terms that pertain to the constitutive description of a material. Apart from this it is shown that the Zaremba–Jaumann stress rate can lead to inconsistencies. This is, however, rather of academic importance and it appears that the use of Ṫ instead of any objective stress rate produces only minor or even undiscernible errors. Finally, a question referring to limit states is addressed, which is of particular interest with respect to hypoplasticity: should the limit state be defined by Ṫ = 0 or by T̊ = 0 ? Copyright © 2003 John Wiley & Sons, Ltd.