ИСТИНА

This study presents an elastic/plastic model that neglects strain hardening during loading, but accounts for the Bauschinger effect. The new model possess the mathamethtical features that express the behaviour of several materials such as high strength steels reasonably well. Previous attempts to describe the behavior of this kind of materials have been restricted to a class of boundary value problems in which the state of stress in the plastic region is completely controlled by the yield stress in tension or torsion. In particular, the yield stress is supposed to be constant during loading and the forward plastic strain reduces the yield stress to be used to describe reversed yielding. The new model generalizes this approach on plane stress problems assuming that the material obeys the von Mises yield criterion during loading. Then, the model is adopted to describe reversed yielding in thin hollow discs subject to external pressure. This study obtained a semi-analytic solution and a numerical technique is only necessary to solve transcendental equations. Therefore, the solution may serve as a benchmark problem to verify the accuracy of numerical codes.