Assessing the nonlinear static stiffness of rail pad using finite element method

Abstract

The unintended vibrations and sound emerging from train operation have an enormous impact on the surroundings, including the deterioration of the way, buildings, and structures. One proposed strategy to mitigate this issue is the installation of a rail pad inserted between the steel rail and concrete sleeper to provide flexibility to the track and cushion the shocks and vibrations generated by the train wheels’ movement. These materials have nonlinear, dissipative properties influenced by service conditions like temperature and toe load. This work aimed to investigate the static stiffness of different materials of the rail pad under the influence of temperature and toe load. The rail pads were categorized as soft, medium, or hard based on static stiffness. A 3D model of the rail pad, steel rail, and concrete sleeper was simulated and analyzed using ANSYS FEM software. The neo-Hookean model was used to model the rail pad, and the isotropic elasticity model was used for the steel rail and concrete sleeper. The static stiffness of the ethylene propylene diene monomer (EPDM) pad was 85.42 kN/mm, lower than that of thermoplastic elastomers (TPEs, 138.98 kN/mm) and ethylene vinyl acetate (EVA, 303.70 kN/mm) under reference conditions (20 °C), without including toe load effects. Increasing the temperature decreased the rail pad’s static stiffness, with the highest reduction of 53.49 %. However, increasing the toe load contributed up to a 23.53 % increase in the static stiffness of the rail pad.