The effects of railpad nonlinearity on the vibration of railway tracks under harmonic load

Koroma, S.G., Hussein, M.F.M. and Owen, J.S. (2013) The effects of railpad nonlinearity on the vibration of railway tracks under harmonic load. 11th Biennial International Conference on Vibration Problems, Lisbon, Portugal. 08 - 11 Sep 2013.

Abstract

A major environmental concern related to railway traffic is vibration. A lot of research has been carried out to understand vibration of straight tracks, with less attention been paid to curved tracks. Modelling the dynamic behaviour of a curved railway track is important to understand the physics of generation and propagation of vibration from trains at non-straight sections of tracks. Modelling is also important to assess the current and any alternative track designs from an environmental point of view. In this paper a curved track is modelled and the effect of curvature is investigated. Two models have been developed and their results have been compared. In the first, the curved track is modelled using straight beam elements. In the second curved beam elements are used. For both, the Euler-Bernoulli beam theory has been adopted to describe their bending behaviour. The elements have 12 degrees of freedom accounting for displacements and rotations in the lateral, transverse and longitudinal directions. The excitation comes from an axle traversing the rails with subcritical velocity, accounting for the wheel-rail contact forces. The described models are solved using the Finite ElementMethod. The time domain response of the versine of the curved track due to the passage of the axle is computed. A comparison is made on the efficiency of the two models for different curve radii and frequencies. The two models provide very similar results showing that the piecewise straight beam approximation represents the behaviour of the curved track accurately. Also the curved beam model used in this study shows some limitations for the specific application and therefore the straight element method is recommended.

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