Abstract
In railway track dynamics, the stiffness and damping properties of railpads have a significant effect on track vibration, decay rates as well forces transmitted to the track supporting structure. Many studies have shown that railpads exhibit pronounced nonlinear behaviour, with preload and frequency dependent properties. This paper presents a three parameter railpad model, together with its differential equation of motion and the required model parameters obtained from experimental data. A time domain model of a rail discretely supported on these railpads is then formulated using the finite element method. The model is subjected to static and dynamic loading in order to study the effects of preload and frequency on its dynamic behaviour. Results are shown as time histories and frequency spectra for the track displacements and reaction forces for various preload levels. They emphasise the necessity of accounting for nonlinear behaviour based on the large disparities (up to 20 dB) observed between the linear and nonlinear cases for the parameters used in this study.
Highlights
The type of railpad model adopted in modelling the dynamic behaviour of a railway track influences the accuracy of prediction of vibration of the track, as well as the forces transmitted through the railpad into the track supporting structure
This paper presents a three parameter railpad model, together with its differential equation of motion and the required model parameters obtained from experimental data
Results for the stationary load The validity of the Finite Element Method (FEM) is first checked against the Fourier Transformation Method (FTM) in Section 5.1.1 using linear parameters
Summary
The type of railpad model adopted in modelling the dynamic behaviour of a railway track influences the accuracy of prediction of vibration of the track, as well as the forces transmitted through the railpad into the track supporting structure. Many studies, including [4,5,6,7], have shown that railpads exhibit pronounced nonlinear behaviour and their properties are dependent on preload and frequency. Characterising these dependencies is, to a large extent, subjective to a particular data set and is by no means a generic process. In a subsequent work [13], the calculation of receptances and decay rates of a similar track preloaded with multiple wheels was presented These studies did not, consider the frequency dependent behaviour of railpads as well as the track dynamic behaviour under moving load conditions.
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