Circumferential Corrosion Test of Steel Strand Bundle Based on Metal Magnetic Memory

It is difficult to effectively detect the internal corrosion of bridge stay cables by conventional technology. Aiming at the problem, the relationship between the corrosion of stay cables and the circumferential magnetic flux leakage signal is discussed in this paper. The steel strand bundles were used to simulate the parallel steel strand cables in practical engineering. The detection experimental study on the single and two corrosion points were designed under different corrosion degrees and corrosion location distributions. The circumferential magnetic flux leakage signals of steel strand bundles were plotted into radar images for analysis. The results showed that the radar image of circumferential magnetic flux leakage exhibited abnormal maximum at the single corrosion point, and the corrosion degree was positively correlated with the extreme value. When two corrosion points were adjacent along the circumferential direction, the radar image was presented as "abnormally convex". When two corrosion points were adjacent along the radial direction, the radar image was evenly distributed as "water drop". When two corrosion points were distributed diagonally, the radar image was similar to "notch". According to the obvious differences of each image feature, the circumferential position of single-point corrosion and the relative position distribution of two-point corrosion could be judged. Moreover, a detection method of the cable corrosion position based on "3D radar image" was proposed.