The multiaxial random fatigue criteria based on strain and energy damage parameters on the critical plane for the low-cycle range

In this paper, the authors present a criterion for determination of fatigue life in the low-cycle range under multiaxial stress state. They propose two strain forms and two energy forms of the criterion, depending on a way of determination of the critical plane. The constants from the criterion are determined while fatigue tests under simple loading states, i.e. tension–compression and torsion. All the forms of the criterion include influence of non-proportionality and various frequencies of loading. They can be also applied for random loading. On the assumption of perfect elasticity of the material, it has been shown that the presented criteria reduce to those presented in the previous papers for high-cycle range. It means that they are generalization of the previous criteria to the low-cycle range. Thus, they can be applied in both low-cycle and high-cycle areas.

► The energy criteria are universal in all the range of fatigue life. The equivalent history is defined as combination of the shear and normal component. The criterion takes different forms for different materials. All the criteria can be applied under non-proportional random loadings. They can be also transformed to the form including influence of the loading mean value.