Theoretical and experimental investigation on the magnetomechanical effect of steel bars subjected to cyclic load

Abstract This paper combines Zheng-Liu (Z-L) model and modified Jiles-Atherton-Sablik (J-A-S) model to propose a magnetomechanical model, to investigate the relationship between the fatigue damage of the steel bar and the surface magnetic memory signal, and to analyze and predict the variation trends of the magnetization of steel bar subjected to cyclic loading. Then tensile fatigue tests on HRB400 steel bars were conducted and the surface magnetic flux density of the specimens under cyclic load was measured. The experimental results demonstrate that the magnetic flux density of the specimens showed three stages in the fatigue process. The magnetic flux density changed rapidly in the early and last stages of the cyclic loading, and developed slightly in the middle stage of fatigue. The magnetization of the specimens during the first two stages was mainly affected by the magnetomechanical effect, and the magnetization during the last stage was dominated by the magnetic flux leakage effect. According to the proposed model, the magnetization of the specimens during the fatigue was simulated. Combined with the fatigue damage formula based on the magnetic signal, the magnetic signal curve reflecting the first two stages of fatigue damage was obtained. By comparing the simulation results with the experimental results, the proposed model can effectively describe the variation trends of the magnetization of the steel bar during the fatigue.