Studies on the Spatial Location Method of Corrosion Defect in Bridge Cable Considering Self-Magnetic Flux Leakage Effect

Abstract

Abstract To detect the hidden defects of ferromagnetic components, it is crucial to first locate the position of defects. In this paper, the three-dimensional magnetic dipole model of a solid columnar structure with a sector cube defect was built to theoretically explain the self-magnetic flux leakage effect of the bridge-stayed cable. The uniform or linear distribution of charge density on specific defect planes was considered in the model. Then, an experimental study on the defective steel strand cable specimens under different corrosion degrees was carried out. The results show that the corrosion accelerates the variation of magnetic signal Bz near the corrosion region, and the phenomenon is consistent with the theoretical model. Moreover, the relationship between the normalized signal Bznor and the corrosion factor αφ reveals the influence of the corrosion defect on the magnetic signal intensity in different detection positions, demonstrating the three-order polynomial growth trend. Combined with the axial and the circumferential scanning, the spatial location method of the corrosion defect was proposed for the detection of the bridge-stayed cable.