Prediction of fatigue damage in ribbed steel bars under cyclic loading with a magneto-mechanical coupling model

As a ferromagnetic material, the magnetization of ribbed steel bars will change with the development of fatigue damage under cyclic loading, which can be used to evaluate the fatigue damage state of steel bars. However, the quantitative relationship between fatigue damage and the variation in magnetization is still unclear, and the existing magneto-mechanical model cannot be applied to ribbed steel bars directly. To accurately predict the magnetization and the fatigue damage state during fatigue, it is also necessary to consider the influence of stress concentration caused by ribs on stress and fatigue life. This paper proposes a magneto-mechanical model suitable for ribbed steel bars, which use the Neuber law and Coffin-Manson relationship to determine the stress range and fatigue life under stress concentration. Additionally, the magnetic induction intensity of the HRB400 ribbed steel bar in the tensile fatigue test was measured to verify the proposed model, and the mechanism of the magnetization change trend during fatigue was analyzed in detail. Through the fatigue damage formula based on the magnetic indicator, the simulation and experimental comparison results show that the proposed model can effectively describe the fatigue damage state of ribbed steel bars in the fatigue.