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PROCEEDINGS OF THE SECOND INTERNATIONAL CONFERENCE ON RAILWAY TECHNOLOGY: RESEARCH, DEVELOPMENT AND MAINTENANCE
Edited by: J. Pombo
Influence of Rail Top Contamination on Transient Rolling Contact of a High Speed Driving Wheel
X. Zhao, Z. Wen, M. Zhu and X. Jin
State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu, China
X. Zhao, Z. Wen, M. Zhu, X. Jin, "Influence of Rail Top Contamination on Transient Rolling Contact of a High Speed Driving Wheel", in J. Pombo, (Editor), "Proceedings of the Second International Conference on Railway Technology: Research, Development and Maintenance", Civil-Comp Press, Stirlingshire, UK, Paper 13, 2014. doi:10.4203/ccp.104.13
Keywords: rail contamination, rolling contact, high speed railway, slip-adhesion distinction, traction, creepage, surface damage.
The high speed rolling contact of a wheelset over a contaminated rail was investigated by an improved 3-D explicit FE model. Such a FE model was specially developed for the cases with short low adhesion zones (LAZs, i.e. a contaminated section) and at high speeds, where the high frequency dynamic behaviour of the vehicle-track system dominates. The actual geometries of the wheel and rail were considered, based on which a penalty method based surface-to-surface contact algorithm was employed to solve the transient rolling contact in the time domain. Detailed contact solutions and their derivatives were obtained together with the macroscopic results such as forces and creepages. The vehicle and track sub-systems were modelled properly to take into account the high frequency vehicle-track interactions. A varying COF along the rail was employed to simulate the rail top contamination, and the third body layer was ignored in the mesh. By specifying a time dependent driving torque applied to the wheel axle, different traction efforts were simulated. It was found that the vertical force and the pressure distribution were not influenced by a LAZ. The longitudinal force, however, becomes clearly lower in the LAZ, and much higher as the contact patch re-enters the dry rail section. A similar trend was also observed from the variation of the maximum surface shear stress. Meanwhile, the shape of the surface shear stress distribution and the slip-adhesion distinction changes greatly across the LAZ. Consequently, distributions of the frictional work and the V-M stress become irregular as the LAZ exists. Larger plastic deformation and a higher wear rate were expected at the location where the dry contact starts to be rebuilt. This builds a basis for further studying the damages of the wheel and rail contact surfaces caused by LAZ.
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