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MODELING OF RAIL BAR DYNAMIC GAP AT ITS BREAK FOR DIFFERENT STIFFNESS VALUES OF RAIL BASE

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Subject of Research.The paper deals with questions of operation safety for continuous welded rail track under dynamic loads. We study the gap value formed in the rail bar in view of its possible break under the conditions of dynamic loads caused by the moving train and varying temperatures. Occurring strains are linked to a variable stiffness of the rail track base (ballast). Methods. We studied longitudinal oscillations in a semi-infinite rod under dynamic loads and in the process of thermal expansion of the finite length rod on the elastic-damped foundation. Oscillatory processes in a semi-infinite rod on an elastic foundation was modeled using the extended equation of longitudinal vibrations, taking into account the reaction of the foundation, performing the role of a damper. To determine the state of the model after the damping of oscillations we used the time limiting transition. In solving the problem of thermal expansion of the finite length rod on the elastic foundation we used equilibrium equation for small fragment, which takes into account the thermal load and the elastic force of both the rod and the foundation. Main Results. We have calculated the maximum value of the dynamic displacement of the rod end at different values of parameters. We have obtained the distributions of stresses and displacements along the rod length for different stiffness distribution in the elastic foundation. In the event of accidental break in the rail, the gap value after the damping of oscillations is set at the level of 5-7 cm. We have shown that the amplitude of these oscillations can reach 10-12 cm. The availability of limited stiffness change zones in the rail base causes no significant deformation of rail bars, but can lead to the growth of the gap in the rail bar break. Practical Relevance. The proposed model can be used in the calculation and design of continuous welded rail tracks.

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