Keywords: dynamic response, wheel-rail contact, track irregularities, finite element, vehicle-track interaction.

High-speed railway systems have been built and operated in several countries. As the operating speed of the train becomes higher and reaches 350 km/h or more, the accuracy of the analysis of vehicle-track interaction becomes an important factor to be considered in the railway track design. An important number of research works on this subject have contributed to relevant technical advances in this area. In order to simulate the vehicle-track interactive dynamics many kinds of plane models [1,2,3,4,5,6] in which the train is treated as independent body and three-dimensional models [1,2,3,4,5,6] in which the train is modeled more realistcally have been presented.

The objective of this work is to develop adequate and efficient models for calculation of vertical dynamic traffic load effects on railway track infrastructures, and applications for evaluating the comparative performance of ballast and slab track designs.

The calculations are based on dynamic finite element models with direct time integration and contact algorithms between wheel and rail in order to consider the rail-car interaction. The first part of the paper reports the studies carried out to decide, develop and calibrate the optimal models for the objectives of this work. In particular, quarter bogie models for vehicles, rail-wheel contact with penalty formulations, and two-dimensional spatial discretization were selected as the optimal decisions. Distributed elevation irregularities were generated based on power spectral density (PSD) distributions. Calculations were carried out in the time domain and envelopes of relevant results were obtained for several track designs and speed ranges.

The results obtained include wheel-rail contact forces, forces transmitted to the bogie by primary suspension and forces transmitted to the infrastructure (sleeper or slab) by the railpads. These latter loads are relevant for the purpose of evaluating the performance of the infrastructure. The results are discussed and compared between different track designs and several assumptions for irregularities.

1

S. Timoshenko, D. Young, "Vibration problems in engineering", Van Nostrand, NY, third edition, 1995.

2

L. Fryba, "Vibration of solids and structures under moving loads", Thomas Telford, third edition, 1999.

3

Y. Sun, M. Dhanasekar, "A dynamic model for the interaction of the rail track and wagon system", International Journal of Solids and Structures, 39, 1337-1359, 2002. doi:10.1016/S0020-7683(01)00224-4

4

C. Esveld, "Modern Railway Track", MRT Productions, 2001.

5

K. Vijay, V. Rao, "Dynamics of Railway Vehicle Systems", Academic Press, Canada, 1984.

6

X. Lei, N. Noda, "Analyses of dynamic response of vehicle and track coupling system with random irregularity of track vertical profile", J. Sound Vib., 258, 147-165, 2002. doi:10.1006/jsvi.2002.5107

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