A connexion between the criterion of yield and the strain ratio relationship in plastic solids

Abstract

The assumption that the work done during a small plastic strain is a maximum as the yield - stress criterion is varied is shown to give rise to a connexion between the yield-stress and the strain-ratio relationship. The strain-ratio relationship is that which exists between the ratios of principal stress differences and the ratios of the corresponding strain differences. It is common to assume that this relationship is one of simple proportionality. Experiments, however, show that this assumption is not true in metals. The observed strain-ratio relationship is used in conjunction with the assumption of maximum work during a given strain to calculate the criterion of yield. It is found that this is very close to, but not identical with, the Mises-Heneky criterion.