Two modifications of Jiang criterion for constant amplitude multiaxial loading of AA2124-T851 and SS316L

The aim of this work is to propose a modification of the Jiang criterion (Jiang in Fatigue Fract Eng Mater Struct 23:19–32, 2000), developed for the general multiaxial loading on our own experimental data gained for the aluminium alloy 2124-T851, currently mostly used in the aviation industry, and the stainless steel 316L under combined loading states in low-cycle fatigue domain. Eight strain loading paths with the constant amplitude cycling were considered for AA2124-T851, including the proportional and non-proportional axial-torsional loading. The proposed generalization of the Jiang criterion leads to the modification of the damage accumulation procedure and is consistent with the original criterion. The comparison of predicted and experimental results shows that the improvement of prediction abilities has been achieved. The new criterion is also more conservative than the original one. There is well-known additional hardening due to non-proportional loading for austenitic stainless steels. Therefore, a new non-proportional parameter has been introduced to achieve more reliable results of predictions for proportional as well as non-proportional loading cases in the case of SS316L.