Path‐dependent multiaxial fatigue prediction of welded joints using structural strain method.

The maximum shear strain's rotational conditions are investigated under multiaxial loading. The additional hardening is closely related to the relative value, rotational range, and gradual or severe rotation way of the maximum shear strain change. A novel path‐dependent loading factor is introduced to account for the nonproportional additional hardening effect. Subsequently, a computational formula of the structural strain method is established for the multiaxial loading state. The structural stress/strain terms and the proposed path‐dependent factor are introduced into the existing energy‐based fatigue parameter based on the critical plane model. The proposed fatigue prediction method provides prediction results showing that more than 68% and 87% of the data are within the scatter bands of 3 and 5, respectively, for the selected tube–flange/tube welded joints under multiaxial loading paths. Highlights: Rotational conditions of maximum shear strain affect nonproportional hardening degree.Path factor should incorporate effect of gradual/severe rotation of maximum shear strain.Multiaxial structural strain method is established by equilibrium condition and flow rule.Energy‐based FPw including path factor provides satisfactory prediction for welded joints. [ABSTRACT FROM AUTHOR]