Characteristic of Signal from Magnetic Flux Examination of Loss of Metallic Area in Bridge Cables

Abstract:

Influence of defect length on the signal output from the magnetic flux (MF) examination of bridge cables for quantitative evaluation was studied. Model experiments were conducted to inspect the characteristics of signal output from the MF examination, and to verify the conclusions from magnetic circuit analysis. Finite element method was used to analyze the sensitivity of the defectlength effect to parameters including the defect morphology, percent loss of metallic area (LMA), cable diameter, size of the test device et al. The results show that fluctuation of the signal from the MF examination of the bridge cable is proportional to the percent LMA, and may be disturbed by the length of flaw; the magnetization intensity of steel wires attenuates approximate linearly along the radial direction of cable; the defectlength effect in bridge cable is more significant than that in steel ropes or rods; when the flaw is shorter than the net distance between the magnets, the damage will be underestimated if the defectlength effect is neglected.