Development And Application Of The Barkhausen Noise Continuous Welded Rail Stress Detector

As railway developed high-speed and overload, seamless railway technology is used widely most of the countries in the world. Because seamless railway can't stretch freely, there produces great vertical temperature stress when railway temperature changes. Excessive temperature stress can lead railway to bend and break out and lead vehicle to derail. Ultimately endanger traffic safety. Therefore, it is very important to test vertical temperature stress of seamless railway in railway public sector. Through testing the actual vertical temperature stress of the seamless railway, we can predict the possibility of the bucking-track and off-track, then take measures to repair in time.At present, there are no normal means to measure the stress and the residual stress directly, we can get the size and orientation of the stress indirectly by measuring the change of the materials'certain physical parameters caused by the stress and the residual stress. There are many factors affecting the detection accuracy of these methods. In this paper, we explain the principle of the magnetic Barkhausen noise based on the theory of the magnetic materials and the elasticity, and introduce the magnetic Barkhausen noise stress testing technology developed on the basis of these theories. We develop the magnetic Barkhausen noise continuous welded rail stress detector based on the former work. The whole system of the magnetic Barkhausen noise continuous welded rail stress detector consists of sensors, magnetic circuit, signal processing circuit, A/D converter circuit and data display circuit, etc.In this paper, we study the load capacity and the impedance matching of the amplifier circuit, and analysis the influence of the magnetic Barkhausen noise signal affected by different voltage. We do tensile and compression experiments, then study the tensile and compression blocks intercepted from U74 rail and analysis the relationship between magnetic Barkhausen noise signal and stress. Finally we apply this detector to test the internal stress of a section of seamless railway which is selected from Beijing Fengtai district's public works section. We study the size and distribution of the stress near the welded joints of railway waist structure. It is very important practical significance to ensure trains'operational safety on line.