Magnetic flux leakage detection method by the arrays consisted of three-dimensional hall sensor for rail top surface cracks

Abstract

It is difficult for a single sensor to fully grasp the leakage magnetic flux properties of the cracks on the top surface of the rail. Therefore, A square array, a circular array, and a cross array which be consisted of three-dimensional hall sensors is designed. The rail inspection vehicle carries the different kinds of arrays to detect magnetic flux leakage for the cracks on the top of rails of different lengths through different paths. Analyse the change law of magnetic flux leakage signal, extract the ring-differential characteristics of each dimension and the geometric characteristics of the peak height, waveform width, envelope area, peak and valley width of the magnetic flux leakage signal curve, then analyse the influence on the magnetic flux leakage signal when the rail inspection vehicle passing through the cracks from different paths. Experimental results show that the detection by different kinds of arrays can dig out more featured information, and the offset degree of the detected magnetic flux signals from the sensor arrays has relationship with the path which the rail inspection vehicle passed through and the centre line of the sensor array carried on the rail inspection vehicle.