A new signal processing method for the nondestructive testing of a steel wire rope using a small device

Problems arise in the detection of defects in wire rope by magnetic flux leakage testing. The most obvious problems are that the excitation devices are cumbersome and inconvenient and the signal-to-noise ratio of damage signals is often low. This paper proposes a small detector. Compared with traditional detection devices, the proposed device has the advantages of a simple structure, easy installation, low weight and good portability. The weight of the device is only 508 g. The surface of the wire rope is characterized by wires and strands. The amplitude of the strand-waveform magnetic signal generated by the special helical structure of wire rope is larger than that of the defect signal. The magnetic image is processed using an adaptive spatial notch filter and the gradient method, and the detection results are analyzed. The strand-waveform magnetic signal cannot be completely eliminated, and not all defects can be detected. A new method is proposed to eliminate strand-waveform noise using the instantaneous phase solution in Hilbert transform and wavelet analysis. Experiments show that the proposed method suppresses noise well and detects and accurately locates all defects.