Research On Rail High-speed Inspection System For Inspection Vehicle

The rail crack defects which caused by wheel rail rolling contact fatigue(RCF), rail crack defects will easily lead to major railway traffic accidents, this damage is a serious threat to the safety of the railway operation, an accurate and effective inspection equipment for measuring the rail top surface crack of is urgently needed. For magnetic flux leakage(MFL) detection technology has the advantages of the simple sensor structure, high sensitivity, can realize the non-contact detection, it is widely used in Non-Destructive Testing(NDT) and evaluation of structural defects. Combined with the electromagnetic characteristics of rail and other ferromagnetic materials, as well as the surface crack detection requirements of rail top, the MFL detection technique is suitable for the surface crack detection of rail in high speed.DCMFL detection technology is used as the main theories of this thesis. First, combined with the theory of electromagnetic field, the basic principle of leakage magnetic field was analyzed. Then, hardware and software part of this inspection system were designed. Finally, with the integrated system, the experiment of the calibration of eddy current displacement sensor, the experiment of acquisition program, as well as the experiment of variable speed turntable and inspection vehicle had been conducted. Experimental data analysis shows that the system can effectively measure the lift-off value between the probe and the tested rail, which ensures the safety of detection of inspection vehicle. The continuous and trigger mode of the system sampling program ensure that the loss of data does not occur, the real-time processing and display and network transmission of experiment data are realized. Frequency characteristic of interference signal caused by body vibration of the inspection vehicle was analyzed and a data processing method which combined with wavelet denoising and high-pass filtering was proposed in this paper. With effective filtering of interference signal, the recognition and analysis of damage defects of the railway rail can be easier. Visualization of the crack defects was achieved with the magnetic flux leakage imaging based on the testing data. The imaging can quickly and intuitively reflect the distribution and characteristics of crack defects on the rail surface, which verifies the feasibility and practicality of this system for high-speed inspection of railway.