Shear-normal stresses interaction in multiaxial fatigue under nonproportional loading, part 2: multiaxial fatigue damage model and validation

Purpose The study aims to propose a new multiaxial fatigue damage parameter. Design/methodology/approach Using the proposed stress analysis method proposed in part 1 and results of the design experimental program, the proposed formula is introduced. Findings The performance of the proposed formula shows encouraging accuracy. This performance is evaluated via the comparison of the proposed formula with other well-known ones. Research limitations/implications The proposed formula requires fatigue input data for non-proportional loadings in the low-cycle regime to predict the fatigue life in that regime. While accessing the available data in high-cycle fatigue is sufficient for life prediction of the non-proportional loadings in the high-cycle regime. Practical implications The paper introduces the concept of the normal-shear stresses interaction in a multiaxial fatigue field. The importance of this phenomenon is evaluated via several available data. Originality/value This paper fulfils an identified need to predict the fatigue life under the proportional and non-proportional multiaxial loadings.