An energy‐based approach for uniaxial fatigue life estimation under asymmetric cyclic loading.

Energy parameter formed by multiplying the maximum strain range and the peak stress has the problem that one value may correspond to multiple fatigue damage states. For this issue, a new energy parameter suitable for tension–compression is proposed, which includes an improved strain‐energy model and a strain‐energy ratio. The improved strain‐energy model deduced by judging the volume change of the micro‐element has positive and negative function which can use to distinguish tensile and compressive deformation. The strain‐energy ratio is established to characterize the alternate tensile and compressive deformation under asymmetric cyclic loading. Then, applying fatigue test data, a modeling approach for fatigue life estimation based on the strain‐energy ratio is proposed, and three example models are also exhibited. Finally, according to the example model, the case of a cantilever beam under asymmetric cycle loading is carried out. The results illustrate the feasibility of the improved energy parameter in characterizing tension–compression state and the applicability of the strain‐energy ratio‐based model in fatigue analysis. Highlights: The energy parameter has a problem that one value may correspond multi‐state.The improved strain‐energy model has positive and negative properties.Strain‐energy ratio can represent tension–compression cyclic characteristics.Fatigue life model based on strain‐energy ratio exhibits E–N curve group.Under heavy load, fatigue damage should fully consider alternating deformation effect. [ABSTRACT FROM AUTHOR]