Research On Simulation Of Curved Switch Rail Wear In High-Speed Turnout

The rail wear control in turnout operation is one of decisive factors to affect its own service life and the riding quality when the train passes over a turnout. Based on the former researches worldwide, the article deeply studies on rail wear damage mechanism of turnout and the effect on the comfort and the security of driving, mainly focusing on the following subjects:1. wheel/rail rolling contact in turnout zoneWheel/rail rolling contact behavior in turnout zone has been studied based on the basic theories of rolling contact. The number, shapes and areas of contact patches and the maximum contact stresses are calculated to compare the application of Hertz contact theory, Semi-Hertzian method, CONTACT and finite element method into analysis of wheel/rail normal contact problems in turnout zone, by taking the LMA wheel tread contact with the new and worn switch rail profiles as example. And the creep forces, distributions of adhesion/slip region, areas of slip region and computational efficiency are calculated to compare the solution of Shen-Hedrick-Elkins theory, Kalker’s simplified theory, CONTACT and Semi-Hertian method for wheel/rail tangential contact problems in turnout zone. On this basis, the subroutine to solve the wheel/rail rolling contact problems is programmed, which can provide the theoretical support for the simulation of dynamic interaction between vehicle and turnout and the rail wear prediction of turnout.2. Establishment of vehicle-turnout coupled vibration model and its solutionThe vehicle-turnout coupled vibration model is established to predict the switch rail wear and analyze the influence of rail wear on the system vibration. The coupled model consists of vehicle submodel and turnout submodel. The vehicle submodel is made up of vehicle body, bogies and wheelsets, totally 31 degrees of freedom are considered:a vehicle or a bogie has 5 degrees of freedom:vertical and horizontal movement, pitch, yaw, side-roll and a wheel-set has 4 degrees:vertical and horizontal movement, yaw, side-roll. The turnout submodel is comprised of a switch panel, a crossing panel and a closure panel, in addition, the components of the jacking block, the spacer block, the limiter and the conversation and locking advice and variable cross-section characteristics of switch rail and the nonlinear supports of the sliding bed are considered. The above submodels are coupled by the model of wheel/rail contact, the formation of the equation of coupled system is established based on the Hamilton principle, and a computer program is developed for solving the formation.3. Remarkable affecting factors of rail wear behaviors in turnout zoneThe remarkable affecting dynamic responses of rail wear are focused on and the influence of elastic shear deformation and wear models on rail wear behavior is analyzed on the basis of relevant tests and theoretical researches about wheel/rail wear. The method of using Plackett-Burman unreplicated saturated factorial designs is proposed to analyze the impact of each factor on the rail wear based on the orthogonal tests, and the remarkable affecting parameters of rail wear in turnout zone are screened on the basis of methods of graphical analysis and numerical analysis, which provides support for the rail wear prediction in turnout zone.4. Prediction and simulation of switch rail wearOn the basis of switch rail wear prediction process, the method of switch rail wear prediction is established and the relevant program is wrote by synthesizing vehicle/turnout coupled dynamics, wheel/rail rolling contact theory, the rail wear model, wear superposition method and rail profile update method. The switch rail profile evolution is simulated at different passing weight by taking typical sections of switch rail as example, furthermore, the influence of vehicle axle load, speed, gauge, rail cant and friction coefficient on the rail wear in turnout zone.5. Influence of switch rail wear on the system vibrationThe features and patterns of rail wear in turnout zone are summarized. The vehicle/turnout coupled dynamics are applied to analyze the influence of rail wear on the system vibration by taking side wear of switch rail, deviation of height difference between stock rail and switch rail, vertical wear of stock rail as example, and the calculations include wheel-rail interaction forces, safety and stability of vehicle running. The above could provide theoretical support for the switch rail wear limit.