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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 93
PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY
Edited by: B.H.V. Topping, J.M. Adam, F.J. Pallarés, R. Bru and M.L. Romero
Paper 12

The Influence of Track Modelling Options on the Simulation of Train-Track Interaction

S. Alfi, S. Bruni and E. Di Gialleonardo

Department of Mechanical Engineering, Politecnico di Milano, Italy

Full Bibliographic Reference for this paper
S. Alfi, S. Bruni, E. Di Gialleonardo, "The Influence of Track Modelling Options on the Simulation of Train-Track Interaction", in B.H.V. Topping, J.M. Adam, F.J. Pallarés, R. Bru, M.L. Romero, (Editors), "Proceedings of the Tenth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 12, 2010. doi:10.4203/ccp.93.12
Keywords: track models, train-track interaction, rail vehicle stability, wheel-rail contact forces.

Summary
In the present paper the effect of track modelling on the simulation of train-track interaction was studied, focusing attention on the stability analysis of a vehicle and on its response to a stochastic excitation arising from rail irregularity.

A multi-body model of the vehicle has been set-up, together with three different track models having increasing complexity:

  • rigid track
  • a moving track model (sectional model with three degrees of freedom);
  • a complete finite element model of the track.

As far as vehicle stability is concerned, it has been shown that both the vehicle critical speed and the dominant frequency of the hunting motion are highly influenced by the degree of detail used in modelling track flexibility.

Neglecting or considering a simplified model for track flexibility may result in significant modelling inaccuracy, which, as shown in the paper, leads to an overestimation of the critical speed of up to more than 10% and an overestimation of the dominant frequency of the hunting motion up to more than 20%.

Regarding the vehicle response to a stochastic excitation from track irregularity, the analysis of the spectrum of the wheel-rail contact forces, has shown that the introduction of track flexibility does not significantly affect the harmonic components up to 20 Hz, whereas the rigid model is not able to reproduce the dynamic amplification observed using flexible models and overestimates the harmonic contribution at higher frequencies. Comparing the results given by the sectional and the complete model it is observed a difference both in the resonance frequency, especially with regard to the vertical component, and in the corresponding dynamic amplification.

The influence of speed on rms values of the vertical and lateral components of wheel rail contact forces was investigated as well. It is shown that the rigid track model provides a higher rms value for both the components analysed, whereas differences between sectional and complete model may be ascribed to the resonance frequency, which is different between the two track models.

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