Magnetic Flux Leakage Testing of Wire Rope Defects with Denoising

As an efficient non-destructive testing method, magnetic flux leakage (MFL) testing has been widely used for inspecting wire ropes. In this method, many factors can affect the MFL signal, and the accurate extraction of defect signals is a fundamental issue that bears consideration. For a wire rope with certain structure, the strand-waveform noise is the most important and most energy-efficient noise. We propose a new denoising method that eliminates the strand-waveform noise in the magnetic flux leakage testing of wire rope defects, then detect the defects and determinates the region. For a wire rope with certain structure, the strand-waveform signal shows a certain regularity both in the axial direction and in the circumferential direction. We eliminate the strand-waveform noise by using the instantaneous phase solution in Hilbert transform. Compared with the traditional method, this method not only suppresses the strand-waveform noise but also highlights the defects signal. This method can realize real-time processing. Experimental results show that this method can well suppress the strand-waveform noise, and can accurately detect the defects.