Effect of distributed support of rail pad on vertical vehicle-track interactions

Abstract Rail pads are important components in railway tracks that greatly influence the vehicle-track interactions. A vehicle-track vertically coupled dynamics model that considers the distributed support of rail pad has been proposed in this paper. The rail is modelled as a Timoshenko beam with nonlinear distributed supports, which can reflect both the finite support length of the rail pad and the continuity of the rail. Based on the mode superposition method, the matrix form of the equations of motions is derived for iterative computation. The comparisons between the proposed model and the traditional model of discrete elastic point support are conducted through numerical simulations. The influence of rail pad support length on wheel-rail interaction and pad stress are investigated. The results indicate that the proposed model can provide a more precise result around the “pinned-pinned” frequency. Besides, the traditional model overestimates the rail deformation, and the dynamic responses are magnified in low-frequency vibration analysis. It also reveals that increasing the rail pad support length can mitigate the wheel-rail interactions and the vibration of the ballasted track structure. Furthermore, both ends of rail pad have been proved to suffer larger stress comparing with the middle area when the wheel is rolling over a sleeper.