An investigation into the vertical dynamics of tracks with monoblock sleepers with a 3D finite-element model

Abstract

This paper investigates the vertical dynamic behavior of railway tracks with monoblock sleepers. Whole- and half-track finite element (FE) models are presented in which the rails and sleepers are represented with their nominal 3D geometry using solid elements. The railpad encompasses the rail seat area modeled as multiple spring–damper pairs. The 3D FE models are employed for three purposes. First, the stiffness and the damping of the railpad and ballast are derived by fitting the simulations to a set of field hammer test measurements. Second, the origins of six of the seven main characteristics are identified. Third, the influence of the railpad representation on the track’s dynamic response is studied. The results show that, in contrast to the 3D FE half-track model, the 3D FE whole-track model reproduces six of the seven main vertical track characteristics with a maximum deviation of 10% from the measured frequencies. The seventh characteristic is reproduced at approximately the measured frequency when the frequency-dependent stiffness of the railpad is considered. This model can be used to derive track parameters that will aid in the study of track degradation.