Nondestructive Testing of Train Wheels Using Vertical Magnetization and Differential-Type Hall-Sensor Array

This study proposes a differential-type Hall-sensor array and vertical magnetizers used to improve the detection ability of crack in express-train wheels. In addition, exclusive parallel signal-conditioning circuits, analog-to-digital converting circuits, and interface were developed to reduce measurement time. The permanent magnet applies a vertical magnetic field on the wheel, while the differential-type linearly integrated Hall-sensor array measures the distribution of the magnetic field around a crack. The proposed method was verified by experiments.