Keywords: railway dynamics, vehicle-track interaction, track irregularities, wheel-rail contact forces, wheel profile wear.

The increase of the world population, the growing energy price and several environmental issues have accelerated the development of the railway transport during the last decades. To fulfill the higher demand for travel of persons in the modern society, passenger trains have to travel faster, with a high level of safety and comfort. In addition, the higher demand for the transport of goods requires a more efficient railway fret system so freight vehicles are required to carry larger loads per axle. Nowadays, one of the most sensible issues in the railway industry is the damage to vehicles caused by the track conditions and the infrastructure deterioration due to the train traffic. Therefore, it is essential to acquire a better understanding on how the operation conditions influence the wear evolution of the railway wheels and the consequences of their changing profiles on vehicle-track interaction forces.

In this work, a computational tool [1,2,3], based on a multibody formulation, is used to simulate the dynamic performance of integrated railway systems. The tool is also able to predict the wear evolution of the railway vehicle wheels. First, the tool is applied to realistic operational scenarios in order to study how the wheel wear evolution is affected by the track conditions, defined by the track geometry and by its irregularities. Then, special attention is given to the comparison of the vehicle-track interaction forces obtained during the operation of a trainset, running at different velocities, on tracks with and without irregularities. These studies are performed with the railway vehicle assembled with wheels having new and worn profiles in order to evaluate how the wear state influences the loads transmitted to the railway infrastructure.

The wheel wear results obtained here show that the levels of track irregularities considered have a non significant influence on the wear progression. Another conclusion of the studies conducted here is that the wear state of the railway wheels has a negligible influence on the loads imposed on the track. On the other hand, it is observed that, when negotiating a curve, the vehicle velocity has a very significant influence on the track loads, especially on the lateral track forces.

The study on how the track imperfections affect the vehicle-track interaction reveals that the track irregularities produce oscillations in the lateral and vertical track forces. Such oscillations promote significant increments in the track loads, which can reach values more than 50% higher than when considering a track without perturbations.

1

J. Pombo, X. Quost, N. Tassini, J. Ambrósio, M. Pereira, R. Lewis, R. Dwyer-Joyce, C. Ariaudo, N. Kuka, "A Railway Wheel Wear Prediction Tool Based on Multibody Software", Proceedings of VSDIA 2008 - 11th Mini Conference on Vehicle System Dynamics, Identification and Anomalies, Budapest, Hungary, November 10-12, 2008.

2

N. Tassini, X. Quost, R. Lewis, R. Dwyer-Joyce, C. Ariaudo, N. Kuka, "Parametric Study of a New Railway Wheel Wear Prediction Tool Based on Commercial MBS Software", Proceedings of EURNEX-ZEL08 Conference, Zilina, Slovakia, June 4-5, 2008.

3

N. Tassini, X. Quost, R. Lewis, R. Dwyer-Joyce, C. Ariaudo, N. Kuka, "A Numerical Model of Twin Disc Test Arrangement for the Evaluation of Railway Wheel Wear Prediction Methods", Submitted to Wear, 2009.

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