Determining the fatigue process in ribbed steel bars using piezomagnetism

Abstract

The research presented here investigated the relationship between piezomagnetic signals and fatigue damage in ribbed steel bars. Two groups of HRB400 ribbed steel bars were separately tested using either uniaxial static or cyclic tensile loading. Subsequent piezomagnetic signals were recorded in real-time. Results demonstrated that there was a relatively extreme—but stable—value ratio for the piezomagnetic curves obtained under both static and cyclic stress. The microstructure and surface features presented by ribbed steel bars resulted in different theoretical analyses when examining stress-induced magnetization. There were significant differences in the time-varying piezomagnetism trace and piezomagnetic hysteresis loop for different stages. These differences revealed the evolution of fatigue damage, allowing for signs of impending terminal failure. Piezomagnetic parameters developed in parallel with the accumulation of fatigue damage and the transitions between three fatigue stages were determined using piezomagnetic signals. The percentages from three stages of fatigue were approximately 2.1%, 95.2%, and 2.7%. Collectively, these results may suggest the effectiveness of this nondestructive technique for analyzing the fatigue process in ribbed steel bars.