Limiting stress of metals and the limiting state under creep conditions

We show that, as long as one deals with a plane stress state, the Coulomb-Mohr fracture criterion traditionally used in soil and rock mechanics is in a rather good agreement with the results of fracture experiments for metal materials under the conditions of creep caused by a long-term action of a constant load. We perform statistical analysis to compare the proposed theoretical limiting-stress-fracture-time dependencies with the experimental results given in [1-3] and the results of computations by other authors [1, 4, 5]. Just as in [6], the limiting state arising under the conditions of creep caused by long-term loading is considered in the case of plane strain. We use the solutions of the rigid-plastic problems on the pressure exerted by a flat die on a half-plane and the extension of a strip with angular notches to find the fracture time for the corresponding problems in the setting of a perfectly rigid-creeping body.