An Upper Bound Solution for Axisymmetric Extrusion and Drawing Considering a Generalized Yield Criterion

The yield criterion of many metallic materials differs from the von Mises yield criterion. However, the available upper bound solutions are almost all restricted to this criterion. The objective of the present paper was to derive an upper bound solution based on a generalized yield criterion for evaluating the extrusion and drawing force, assuming a conical die. The solution method differs from the conventional method used in conjunction with the von Mises yield criterion. The development of this method is necessary, since the work function is not readily expressed as an explicit function of strain rate invariants if the generalized yield criterion is adopted. The solution is illustrated using numerical examples, which show the effect of the yield criterion on the limit load.