The vertical stiffness and damping of studded rubber railpads have been measured. The results were obtained as functions of frequency under different static preloads. Measurements were made both in a complete track and in a test rig. The field measurements gave results in the frequency range 0.010 to 200 Hz and the laboratory measurements in the range 50 to 1000 Hz. In both kinds of measurements the stiffness of the railpads was seen to increase with preload, but the stiffness only increased slightly with frequency. The loss factor was seen not to vary much either with preload or with frequency. Only for low preloads did the loss factor increase with frequency for high frequencies. Field measurements were also performed for polymer-based railpads. They were seen to be much stiffer than the studded railpads. The stiffness of the polymer-based pads was independent of preload, but increased with frequency. The loss factor of the stiff railpads was close to the loss factor of the studded railpads. A fractional derivative model of viscoelasticity was presented. The four parameters of the model were fitted to the experimental data from the laboratory measurement. A different set of parameters was needed for each preload since the fractional derivative model is linear, whereas the railpad stiffness is non-linearly dependent on the preload. For each preload the fractional derivative model resulted in a good fit, especially to the measured stiffness of the railpads. The present measurements have led to a better knowledge of the behaviour of the railpads. They also provide the information needed to find accurate values of the parameters in the proposed mathematical model of the railpads. When the model is included in a complete track model, more accurate calculations of the track response to a moving train can be obtained.
Frequency dependent stiffness and damping of railpads
Untersuchungen zur Frequenzabhängigkeit von Steifheit und Stoßdämpfung von Schienenunterlagen aus Gummi und Polymerwerkstoff
1997
12 Seiten, 14 Bilder, 1 Tabelle, 24 Quellen
Aufsatz (Zeitschrift)
Englisch
Frequency dependent stiffness and damping of railpads
SAGE Publications | 1997
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