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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 27

The Effect of Track Defects on the Dynamics of Wagons under Brake-Traction Torque

Z. Zhang1 and M. Dhanasekar2

1Parsons Brinckerhoff, Brisbane, Australia
2Queensland University of Technology, Brisbane, Australia

Full Bibliographic Reference for this paper
Z. Zhang, M. Dhanasekar, "The Effect of Track Defects on the Dynamics of Wagons under Brake-Traction Torque", 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 27, 2010. doi:10.4203/ccp.93.27
Keywords: braking-traction torque, wheel unloading, lateral track irregularity, vertical track irregularity, wagon yaw, wagon roll.

Summary
Most of the wagon dynamics simulation packages that primarily focus on providing a platform for long distance route simulations with near real-time scenarios are routinely employed with pre-defined speed profiles for dealing those situations. Such fast simulations usually do not include wheelset pitch and hence are incapable to account for the wheelset slip and skid.

This paper describes a mathematical formulation for modelling full wagon systems using a fixed coordinate reference system both in space and time. The wagon consists of one wagon body supported by two bogies one at the front and the second at the rear, and they are connected by massless elastic spring and damper elements.

The geometry of wheel-rail profiles affects the creepageand, or creep and adhesion and they in turn result in the complex dynamic behaviour of wagon. In this paper, the influence of brake and traction torques on wagon dynamics are illustrated using case studies. The sinusoidal lateral track irregularities are reported to reveal their effects on yaw moment and the wheel unloading ratio. Two kinds of magnitude of the sinusoid vertical defects and cross level are used to exploit the wagon roll.

The wagon yaw and roll show a positive propositional relationship to the track defect magnitude. The wagon body yaw largely depends on the magnitude of the track defects. The large brake torque can results in the relatively large wheel unloading ratio on the lateral irregularity compared with the normal level brake torque case and no-torque case. With an increase in the cross level irregularity the wagon roll increases; it also determines when the largest wagon body-bogie roll would occur. The external torque generally does not affect the occurrence of the bogie roll; however, the large external torque is able to greatly change the wagon body roll. The large brake torques generally increase the absolute value of wagon body roll while the traction effects were far more complex. The sinusoid irregularity effect on wagon roll is considered more severe than the cross level irregularity.

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