Some theoretical observations on conical failure criteria in principal stress space (Q1072753)

The properties of the conical failure criteria that lie just inside and just outside the Mohr-Coulomb surface are discussed. Expressions are developed for the maximum stress ratio predicted by these surfaces as a function of the angular stress invariant. For plane strain problems, assuming elastoplastic behaviour, the effect of Poisson's ratio and the dilation angle on the stress paths and failure loads have been expressed in a closed-form solution. Finally, the expressions are confirmed using finite element analysis of a simple boundary value problem.