A NEW MULTIAXIAL FATIGUE LIFE PREDICTION MODEL BASED ON THE NONPROPORTIONAL ADDITIONAL DAMAGE

Based on the critical plane approach, this paper proposed a multiaxial low cycle fatigue life prediction model to correctly account for the non-proportional fatigue life reduction. Different from traditional critical plane models, in which only consider the effect of non-proportional additional cyclic hardening, the new model takes into account the influence of loading paths on fatigue life by introducing a non-proportional additional damage coefficient into the fatigue damage parameter. By taking the maximum shear strain plane and the maximum damage plane as the critical plane respectively, this model can also reflect the importance of the selected critical plane on the predicted life. Demonstrated by using the experiment data of eight kinds of materials from different published references, this new model is capable for application under both proportional and non-proportional loading conditions, which is very convenient for engineering application.