Train Wheel Magnetic Flux Leakage Testing Method Based on Local Magnetization Enhancement

Non-destructive testing (NDT) of train wheels fatigue cracks is a critical technology to ensure railway safety. Early fatigue cracks are small and difficult to detect. In this paper, the magnetic flux leakage (MFL) method is proposed to detect train fatigue cracks. The unsaturated magnetization state near the defect area is revealed through magnetic circuit analysis and finite element methods. As a result, leakage magnetic fields will decay sharply for small fatigue cracks, and they are difficult to detect by the traditional MFL method. To improve the magnetization state near defect areas, a novel MFL method based on local magnetization enhancement is proposed and developed. Experimental verification is also conducted by a train wheel NDT device. Testing results show that this method achieves excellent performance in the detection of defects in train wheels.