Research Of Railtrack Temperature Stress Based On Magnetic Barkhausen Noise Detection

In the new century, China has a rapid development in the field of high-speed rail. With a largenumber of continuous welded rail used, the ability to detect the rail stress distribution accurately hasan extremely important significance for the prevention of rail expansion, especially the temperaturestress.This paper proposed the feasibility of detection of rail thermal stress based on the method ofBarkhausen.Firstly, based on the magnetic domain theory, this thesis analyzed magnetization offerromagnetic materials, introduced the generation process and nature of Barkhausen signal, thetemperature stress of seamless rail and rail expansion capacity, studied the main physical factors ofBarkhausen signal, including the excitation and properties of the material itself, focused in particularon the temperature; Secondly, in order to extract the information which can reflect the change of thestress, we improved the original MBN detection system platform, written real-time data acquisitionand processing procedures in MATLAB. Refer to the spectral characteristics of the MBN signal wedetermined the parameters of the excitation by experimental methods. Finally, to ensure that theA3-steel specimens under the constant stress and the changing temperature, we carried out the thermalstress testing laboratory, and discussed the change of each eigenvalue variation with temperature andstress, to find out the only eigenvalue which has less change with temperature and bigger change withstress and distinguish the impact of temperature and stress on the MBN signals. Then, explained thephenomeomo that the temperature change has impacts on the rail stress from the theoretical view,discussed the impacts of the rail residual stress and the uneven distribution of temperature during theexperiments.In addition to the above, we also analysized the changing of the MBN under the mentioning ofthe magnetization and detection coil, laid the foundation for the follow-up to the rail line inspection.At last, analysized the feasibility of the MBN detection of rail stress by two field tests.