Study On Fatigue Life Prediction And Structural Optimization Of Rubber Pad Under Rail Of Metro Fastener System Under Vehicle Load

At the present,the rail transit industry is developing rapidly in China,and it also puts forward higher requirements for various components of rail structure.The rubber pads under rail of the fastener system provide the necessary elasticity for the track structure and its fatigue performance directly affects the running safety.Therefore,it is of great significance to study the prediction method of its fatigue life and explore its fatigue life under train load to optimize the design of rubber pads.Based on the finite element method,the theory of multi-rigid body dynamics and the theory of fatigue analysis,the fatigue life of the rubber pad under the train load is predicted,and the structural type of the rubber pad was optimized.1.The uniaxial tension test was carried out on the rubber specimen,and the test data were fitted with 6 kinds of super elastic constitutive models of rubber materials through the optimization analysis module of COMSOL,and the fitting parameters and fitting errors of each model were obtained.Finally,the Neo-Hookean model was selected to simulate the deformation characteristics of rubber materials,and the fitting parameters were determined.2.The simplified finite element analysis model of the rubber pad under rail of the metro fastener system and the metro vehicle-track coupling dynamic model were established to calculate the dynamic response of the rail under different working conditions.3.With the help of COMSOL,a multi-physics field coupling analysis software,the fatigue life prediction model of rubber pad under rail was established,and the fatigue life of rubber pad under different train load was analyzed and studied.The results show that the fatigue life cloud map of the rubber pad is roughly the same under different driving speeds and rail corrugation,and the fatigue life of the rubber pad decreases with the increase of the vehicle speed and rail corrugation wave depth.The greater wave depth of rail corrugation,the more obvious influence of rail corrugation wave length on the fatigue life of rubber pad.4.The advantages and disadvantages of different structural types of rubber pads were compared and analyzed with the stiffness and fatigue life of rubber pads.In a certain range,the more grooves,the bigger width and depth of the rubber pad,the smaller the stiffness of the pad,the better elasticity.On the basis of ensuring the bearing capacity,the more grooves and the bigger depth of rubber pad,the greater fatigue life.5.Compared with the grooved rubber pad,the fatigue life of the flat rubber pad is bigger,but the elasticity is poor.Therefore,in order to obtain better elastic rubber pad under rail,the flat pad structure should be avoided in the design.