Average apothem yield criterion and its application to strip forging

A new linear yield criterion, referred to as average apothem (AA) yield criterion is developed in this paper based on the Tresca and Twin Shear Stress (TSS) yield criteria. This criterion is a piecewise linear function and its locus on the π-plane in Haigh Westergaard stress space is an equilateral and non-equiangular dodecagon. Comparison with the Tresca and Mises yield criteria shows that the locus of the proposed yield criterion lies between those of the Tresca and Mises loci and is much closer to that of Mises yield criterion. Further, its specific plastic work rate is developed. As an application of the proposed criterion, the AA yield criterion is applied to the analysis of a generalized worked example of strip forging and an analytical solution of the stress effective factor is obtained. Comparison with the results by Tresca, Mises and TSS yield criteria shows that the proposed criterion provides an intermediate solution between the results of Tresca and Mises criteria.