Design and fabrication of a non-destructive system for detecting and measuring cracks in RDD-S11 rail defect detector equipment

This study aims to design and manufacture a crack detection/measurement system for railway lines. Rolling contact fatigue cracks are among the most significant railway surface defects and most failures and rail fractures arise from this type of defect. In case of well-timed detection of these cracks, the overgrowth of them and subsequently rail fracture could be avoided by preventive grinding. In this study, the capability of two conventional non-destructive methods for crack detection, including Magnetic Flux Leakage (MFL) and Eddy Current (EC) tests, have been evaluated. The results indicate that, despite capability of detecting the position and depth of cracks, the MFL method has several limitations, such as the high weight of the yoke and high field strength, making the probe move harder over the rail. Instead, the EC probes are very light and excite the rail surface with a weak magnetic field, providing a higher scanning speed. Besides, EC probes indicate high accuracy and reliability for determination the location and depth of cracks. In RDD-S11, which is currently being used in lines one and two of Mashhad Urban Railway Company to detect three common defects, the proposed EC sensors have been used.