Research On Temperature Stress Testing Of Continuous Welded Rail By Metal Magnetic Memory Technology

How to Continuous, dynamic, accurate monitoring the temperature Stress of seamless rail is a Long-standing problem for railway sector.Because of the resistance of the welded fasteners and the role of ballast resistance within the continuous welded rail,the thermal expansion and contraction of long rail can only occur within both ends of 100m.The middle part which called the fixed area do not change with the track temperature.So corresponding longitudinal temperature stress is accumulat in rail.Temperatures rise sharply in summer,the track temperature is higher than the Air temperature 20℃.At this time large internal stress is accumulat in railway.When the energy release at shorter length,the expansion of a railway track accur.In the winter tracks temperature is much lower than air temperature,Rail withstand a large tensile strength.When the tensile stress reaches a certain value, it will pull off rail, which will caused a serious rail accident. Therefore, real-time detection of the actual vertical temperature of the rail track is of great significance to maintenance guide of rail track and rail safety assessment on broken rails and expansion rails. This paper focused around research on stress testing of seamless rail by Metal Magnetic Memory technology,Detect the stress concentration of rail track which in ausative time.Thermal stress assessment report of the continuous welded rail is given through field experimental analyse and lab test.The main content include:1. Based on the theories of ferromagnetism and elastic mechanics, the principle of magnetic memory effect is explained. Magnetic dipole model of leakage field testing is introduced and the self magnetic leakage field of ferromagnetic material is analyzed.2. The temperature stress of seamless rail is completely monitored by Metal Magnetic Memory technology in the safety assessment trial trial and massive data is obtained. The stress distribution is comprehensively evaluated by combining other conventional nondestructive testing methods.3. In this paper the design on the hardware and software of the instrument which using MMM technology were given in detail. The analysis on feasibility and veracity was made with the experimental results.