Decay rates of propagating waves in railway tracks at high frequencies

In order to understand long range wave propagation in railway tracks, it is required to identify how far vibrations can travel along a rail. To answer this question, the attenuation characteristics of the main propagating waves are required as a function of distance. In this work, decay rates of propagating waves in railway tracks are investigated for frequencies up to 80 kHz. A numerical method called the wavenumber finite element (WFE) method is utilized to predict decay rates for a rail on a continuous foundation. Damping is introduced in this track model by the material damping in the rail and in the foundation. In order to improve the simulated results, the frequency dependent damping loss factor of a rail has been measured up to 80 kHz on short rail samples. From this simulation, the relative importance of the rail and support damping for the long range wave propagation is determined. In order to validate the simulated results, a field measurement has been performed on an operational railway track. From this experiment, train-induced rail vibrations have been acquired for several running trains travelling over a long section of rail. The measured results are presented for comparison with the output of the simulations and good agreement is found between them.