Research On Continuous Measurement Method For Vertical Wheel-Rail Force

With increase of train speeds and axle loads, interactions between the vehicle and the track are being intensified, which makes rail transport security being more severe.Wheel / rail relationship is the most important relationship in the field of rail transit, and the monitoring of wheel rail force has very special significance. Through the recording and analysis of wheel / rail forces, we can make diagnosis and forecast for all kinds of abnormal condition of track and train equipment, thus the railway traffic safety is guaranteed. Under the background of the development of the railway industry in China, this paper mainly carried out the following research work with the theme of wheel / rail vertical force continuous measurment:(1) According to wheel/rail interaction characteristics and the true restriction condition of track, the finite element model of rail is established by using finite element analysis software ANSYS. Based on the analysis of the strain on the neutral axis of rail web, the paper studies how to select the strain direction to study, and determines the position of the load when the finite element calculation is carried out. By applying vertical load at different locations, the strain distribution on the nertral axis of rail web is obtained, and the variation law is analyzed. According to the results of the simulation, the position for pasting strain gauge and the scheme for bridge test is determined. According to the relationship between the test bridge in this paper and the bridge of the shear stress method, we can know how to distinguish the subsection point position when the wheel rail force is taken out. The influence of the lateral force on the test of vertical force is calculated. The results show that the existence of the lateral force has no influence on the test of vertical force. The inversion of the wheel / rail force is simulated and calculated, and the results have a certain accuracy. Finally,the simulation and analysis of three parameters on the impact of the continuous test program show that the method in this paper can be applied.(2) In view of the common baseline drift and coarse white noise in the wheel / rail force test, the paper puts forward a comprehensive method of removing noise based on wavelet transform. For the baseline drift, two kinds of signals with baseline drift are constructed on the basis of ideal wheel / rail force signal. The most common three kinds of wavelet bases are used to filter the baseline drift, and the suitable wavelet bases are determined through thecomparison of the effect of different wavelet bases on the removal of baseline drift. For the gross white noise, The random white noise is added to the ideal wheel / rail force signal to form a noise signal, and the noise reduction performance of wavelet basis and threshold rule are discussed respectively under hard threshold function and soft threshold function, which determines the combination of wavelet base and threshold rule used for noise reduction.(3) The wheel rail force testing system was developed based on the hardware products and graphical programming language Labview of the National Instrument Corporation. The test system with high reliability and good stability can be adapted to a variety of harsh environment, and the actual operation is also very convenient. The loading test of discrete points is carried out on 60kg/m standard track, and the same change law is obtained compared with the simulation results, which verifies the feasibility of the continuous measurement scheme. Continuous testing of wheel rail force is carried on the narrow track model, and the continuous wheel / rail force output is obtained, which laid the foundation for the continuous testing of the wheel / rail force in the standard track.