Track dynamic behavior at rail welds at high speed |
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Authors: | Guangwen Xiao Xinbiao Xiao Jun Guo Zefeng Wen Xuesong Jin |
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Institution: | (1) School of Civil, Mining, and Environmental Engineering, University of Wollongong, Wollongong, NSW, 2522, Australia |
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Abstract: | As a vehicle passing through a track with different weld irregularities, the dynamic performance of track components is investigated
in detail by using a coupled vehicle–track model. In the model, the vehicle is modeled as a multi-body system with 35 degrees
of freedom, and a Timoshenko beam is used to model the rails which are discretely supported by sleepers. In the track model,
the sleepers are modeled as rigid bodies accounting for their vertical, lateral and rolling motions and assumed to move backward
at a constant speed to simulate the vehicle running along the track at the same speed. In the study of the coupled vehicle
and track dynamics, the Hertizian contact theory and the theory proposed by Shen–Hedrick–Elkins are, respectively, used to
calculate normal and creep forces between the wheel and the rails. In the calculation of the normal forces, the coefficient
of the normal contact stiffness is determined by transient contact condition of the wheel and rail surface. In the calculation
of the creepages, the lateral, roll-over motions of the rail and the fact that the relative velocity between the wheel and
rail in their common normal direction is equal to zero are simultaneously taken into account. The motion equations of the
vehicle and track are solved by means of an explicit integration method, in which the rail weld irregularities are modeled
as local track vertical deviations described by some ideal cosine functions. The effects of the train speed, the axle load,
the wavelength and depth of the irregularities, and the weld center position in a sleeper span on the wheel–rail impact loading
are analyzed. The numerical results obtained are greatly useful in the tolerance design of welded rail profile irregularity
caused by hand-grinding after rail welding and track maintenances. |
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Keywords: | Rail weld Irregularity Vehicle-track coupling dynamics |
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