A design procedure for assessing low cycle fatigue life under proportional and non-proportional loading

This paper discusses the design assessment for structural components subjected to proportional and non-proportional loading. Multiaxial low cycle fatigue lives are influenced by stress and strain multiaxiality, their non-proportionality and a material property that relates to the degree of additional hardening. Many low cycle fatigue studies under proportional and non-proportional loading were carried out in laboratories, but a little study discussed the application of the results obtained in laboratories to an actual design for structural components. This paper proposes a fatigue life assessment for structural components subjected to proportional and non-proportional low cycle fatigue loading. The assessment provides a simple method for evaluating principal strain range, strain multiaxiality and strain non-proportionality. This paper also discusses low cycle fatigue parameters suitable for the life assessment of structural components subjected to multiaxial loading.