Modeling of rail head checks by X-ray computed tomography scan technology

To understand the internal characteristics of the Head Checks (HCs), X-ray computed tomography (CT) were applied to rail HCs inspection and modeling. Typical HCs at the rail shoulder and gauge corner in the high rail of a sharp curve of a heavy-haul railway were observed and sampled. Then, a suitable size and shape of the specimen, including several complete HCs, was designed to scan the internal HCs clearly and rapidly. Based on the CT scanning, the 3D internal information of the HC was extracted and digitized. It was found that the HCs at the rail shoulder and gauge corner propagated inside the rail in a nearly flat plane along a smooth and linear route without many large irregular fluctuations. The propagation rate along the HCs' tip towards to the lateral and longitudinal of the rail was different. The HCs can be modeled by a series of methods like plane rotation projection, abnormal point elimination, shape fitting and spatial positioning, which kept the HCs close to reality. Here, we show that the spline curve, the ellipse and the cubic polynomial curve were suitable for the HC tip shape. The entire HC contour and its ratio of length/width was effected by HC propagation and rail wear. Comparing the length and space angles of the HCs by CT scanning and modeling, the modeled HCs showed high precision compared to the real ones.