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

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 ∂VH/∂x 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.