Nondestructive testing of express train wheel using the linearly integrated Hall sensor array on a curved surface

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Nondestructive testing of express train wheel using the linearly integrated Hall sensor array on a curved surface

Jun, Jongwoo / Choi, Myoungki / Lee, Jinyi / Seo, Jungwon / Shin, Kisu

The wheels of a train are the main component, which supports the weight of the train while in continuous contact with the rail. Any wear and tear in the wheels can gravely influence the safety of an express train traveling at high speeds. Wear and tear in wheels are mainly caused by the following: 1) high vertical stresses at the infinitesimal contact surfaces between the tread of each wheel and the rail; 2) thermal stresses caused by the frictional heat due to braking and wheel movement; 3) nonmetallic impurities formed in the wheels during the wheel manufacturing process. A novel nondestructive testing (NDT) system of high speed and high spatial resolution is needed to detect small cracks on the wheels of an express train. This paper proposes a high-speed NDT system, which uses the Hall sensors array and parallel signal processing circuits. Linearly integrated Hall sensors are arrayed on the cross-section line of a wheel, and the Hall voltage are obtained in the rotation direction. High-speed NDT can be carried out using analog-to-digital converters and micro-processors. The dV_H/dx value, which provides the most important information about a crack, can be obtained by buffering and calculations. The effectiveness of the novel method was verified by applying it in the examination of cracks on a wheel specimen model.