A critical plane‐strain energy density criterion for multiaxial low‐cycle fatigue life under non‐proportional loading

A series of multiaxial low‐cycle fatigue experiments was performed on 45 steel under non‐proportional loading. The present evaluations of multiaxial low‐cycle fatigue life were systematically analysed. A combined energy density and critical plane concept is proposed that considers different failure mechanisms for a shear‐type failure and a tensile‐type failure, and from which different damage parameters for the critical plane‐strain energy density are proposed. For tensile‐type failures in material 45 steel and shear‐type failures in material 42CrMo steel, the new damage parameters permit a good prediction for multiaxial low‐cycle fatigue failure under non‐proportional loading. The currently used critical plane models are a special and simple form of the new model.