Estimation of fully plastic crack tip stresses from equilibrium of least upper bound circular arcs

This paper presents a simple method to estimate fully plastic crack tip stresses based on the equilibrium condition of the least upper bounds for plane strain deformation fields consisting of rigid-body rotation across a circular arc extending from a crack tip across the remaining ligament. The method is applied to deep, single-edge-cracked specimens under combined bending and tension. For various bending-to-tension ratios, the limit loads and crack tip stresses are estimated from the present method and compared with results from finite element limit analyses. The present method gives impressive results.