Researche On The Vibration Performance And Vibration Reduction Method Using The Rail Dampers Of Rail Tracks For High Speed Trains

In recent years,the rail transit develops rapidly towards high speeds,resulting in the vibration problems of the railway become increasingly prominent.The vibration problems caused by high-speed railway mainly come from impact vibration when trains are running on the rail,which will cause a large vibration displacement of the rail and seriously affect the safety of the train and the safety of passengers.Therefore,for improving the vibration of the rail under the action of high-speed trains.The purpose of this paper aims to study the positive effect of suppressing rail vibration by adding the mass blocks（the rail dampers）to the rail starting from the structure of the rail.This has very important guiding significance for improving the service life of the rail and reducing the cost of railway,vibration and noise.In this paper,firstly,the rail is equivalent to the I beam,and based on the finite element software COMSOL Multiphysics,a Kelvin viscoelastic foundation-I beam model and various Kelvin viscoelastic foundation-I-beam-mass blocks models using periodic boundary conditions were established.The contact between the foundation and the I beam,the mass blocks and the I beam,the mass blocks and the mass blocks were connected using springs and dampings.Based on the Hertzian contact theory,the Hertzian contact pressure of the wheel-rail was obtained,and the moving pressure distribution was equivalent to the moving load,which was applied to the I-beam.The correctness of the finite element model was verified by comparison with the analytical solution of Kelvin viscoelastic foundation beam.Then the effects of the mass blocks on the dynamic characteristics of the rail resting on a Kelvin foundation were studied,and the vibration suppression rate of displacement in the vertical direction of rail was used as an index,the vibration suppression effect of the mass blocks were analyzed.The vibration suppression rate of the rail with the long and short mass blocks were obtained.Then a ballastless rail-sleeper-foundation model and two types of ballastless rail-sleeper-foundation-mass blocks models using periodic boundary conditions were established.The contact between the rail and the sleepers,the mass blocks and the rail were connected using springs and dampings.The dynamic response of the rail with and without mass blocks under a steady-state harmonic load and a moving load,and the effect of Rayleigh damping（under a moving load）on the dynamic response of the rail were analyzed.Then we obtained the vibration suppression rate of the rail with the mass blocks between the sleepers and the mass blocks across two adjacent sleepers.Finally,the rail vibration scale tester was designed to study the positive effect of suppressing rail vibration with the rail damper under the drop hammer experiments and the shaker experiments.The main work and results are as follows:（1）The effects of the mass blocks on the dynamic characteristics of rail resting on Kelvin foundation were studied.The research results indicated that the analytical solution of the beam resting on Kelvin viscoelastic foundation obtained by MATLAB software was in good agreement with the numerical solution obtained by the finite element software COMSOL Multiphysics,which proved the correctness of the model.Under a moving Hertzian contact pressure,the greater the speed,the worse the symmetry of the dynamic response curve at the detection point about the moment of reaching the detection point.The vibration suppression effect of the mass blocks at the detection point were proportional to the speed.Compared with the short mass blocks,the long mass blocks had the better vibration suppression effect on the detection point at the same speed.When the spring coefficient decreased,the dynamic response at the detection point was not obvious,and the dynamic response at the detection point was more sensitive to damping coefficient.Compared with the mass blocks and I-beam consolidation,the mass blocks and the I beam connected using springs and dampings had a better effect on suppressing the vibration at the detection point.Moreover,the multiple mass blocks systems were better than the single rail damper systems for absorbing the vibration.（2）The effects of the mass blocks on rail vibration characteristics were carried out.The research results indicated that the first six orders vibration mode of the rail resting on ballastless rail-sleeper-foundation finite element model were lateral vibration.The amplitude of the dynamic response at the detection point was significantly reduced for the cases with mass blocks under a steady-state harmonic load.The damping effect was more effective for the mass blocks across two adjacent sleepers.The peak value of vibration appeared near the center frequency of the load,and the peak value decreased with the distance from the center frequency.Under the action of moving load,the amplitude of dynamic response curve at the detection point increases with the increase of load speed.The greater the speed,the more obvious the damping effect of the mass blocks.The dynamic response at the detection point was more sensitive to damping coefficient.The mass blocks across two adjacent sleepers had a better effect on suppressing the vibration of rail.From the aspect of vibration suppression rate,the mass blocks across two adjacent sleepers was slightly better than the mass blocks between the sleepers.The effect of mass-proportional Rayleigh damping reduced the dynamic response amplitude at the detection point,but the effect was not significant.The effect of stiffness-proportional Rayleigh damping and the combined Rayleigh damping caused the dynamic response amplitude at the detection point significantly decreased,since?₁ contributed less than?₁,there were not much difference between the stiffness-proportional Rayleigh damping and the combined Rayleigh damping.（3）The rail vibration scale experiments were conducted.The research results indicated that the mass blocks had a significant suppression effect on the vertical direction of the rail under the drop hammer experiments,and the long mass blocks had a better suppression effect than the short mass blocks.The mass blocks had a significant suppression effect on the vibration of the rail along the length direction,width direction and vertical direction of the rail,and the vibration suppression effect in the vertical direction of the rail was the best under the shaker experiment.Vibration accelerations at the detection point along the length direction of the rail were always characterized by 50 Hz and 99 Hz two main frequencies,and it had a significant suppression at 50 Hz.Vibration accelerations at the detection point along the width direction of the rail were always characterized by 50 Hz,99 Hz and 148 Hz three main frequencies,and it had obvious suppression at 50 Hz.The vertical vibration accelerations at the detection point were always characterized by 50 Hz,99 Hz,148 Hz,and 198 Hz four main frequencies,and the suppression was obvious at 99 Hz.