Keywords: solid railpad, finite element model, vertical railway track dynamics, hammer test, spring-damper railpad, implicit-explicit finite element aproach.

In this paper, the influence of modeling solid railpads on the vertical dynamics of railway tracks with monoblock sleepers is investigated. A three-dimensional finite element model is presented with two different railpad representations: (1) multiple spring-damper pairs and (2) solid railpad. With the two models, hammer tests are simulated in the time domain, and the calculated response is transformed into the frequency domain to compare the numerically calculated characteristics to the measured ones. Seven main characteristics were identified for tracks with monoblock sleepers. The numerical results show that the model with solid railpads reproduces the seven characteristics at the half maximum frequency difference than the conventional model with spring-damper pairs (i.e. 9% and 18% respectively). The Poisson's effect and the damping of the ballast were the key aspects to closely fit the model with solid railpads to the measurement. From the practical point of view, the model with solid railpads can be used to derive track parameters so that the deterioration of tracks can be investigated.

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