Quantitative Detection of Local Flaw Under the Lift-Off Effect for Steel Wire Ropes

The quantitative analysis of steel wire rope (SWR) is critical for judging its remaining strength and serves as the basis for determining its retirement criteria. However, in magnetic flux leakage (MFL) detection, the lift-off change generated during the movement causes the detection signal to fluctuate, thereby interfering with the quantitative analysis of local flaws (LFs). With the help of the intrinsic characteristic of SWR structure, a quantitative LF detection method with MFL rectification based on strand signals is proposed in this article. The analytical models of LF and strand signals under ideal conditions and the lift-off effect are built. Through calculating lift-off parameters, LF signals are rectified to perform quantitative analysis. Through the case study, the detection results of 2.47 and 4.54 broken wires are 2.55 and 4.67. Compared with the diagnostic results before MFL signal rectification and different quantitative methods, the proposed method can greatly improve the accuracy and robustness of quantitative LF analysis under different lift-off scenarios.