Predicting the effect of temperature on the performance of elastomer-based rail damping devices

Description/Abstract

Rail dampers have been developed in recent years, formed by an elastomeric material and embedded steel masses. The loss factor and stiffness of the elastomer are very important for the performance of the system but, unfortunately, both are sensitive to changes in the temperature. Although having a high loss factor gives good noise reduction, it also means greater variation of stiffness, and consequently tuning frequency, with temperature. To investigate the effect of the temperature on the performance of a generic rail damper, a Timoshenko beam model of the track is used, to which is added a single-frequency tuned absorber. The noise reduction at each frequency is found from the ratio of the decay rates of treated and untreated beams. This is introduced into a typical noise spectrum obtained using TWINS. Account is next taken of the physical link between the damping loss factor and the stiffness variation with temperature. By assuming a constant loss factor, the rate of change of stiffness with log frequency is established. Then, using the time-temperature superposition principle, this can be expressed in terms of a temperature-dependence. This is finally used in the prediction of decay rates and thereby noise reduction. The results allow the relative importance of a high loss factor or a temperature-independent stiffness to be assesse