The Effect of Track Irregularities on Wheel-Rail Contact Relationship
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Date
2016-06
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Addis Ababa University
Abstract
Track irregularity is an inevitable problem in any rail network and it is the source
of track deterioration and degradation. This becomes evident in railway projects
spanning cities. Hence, the effect of track irregularities on wheel-rail contact
relationship is studied with the aim to solve the contact geometry and contact
pressure problems induced by these track irregularities. In this regard,
independent analysis and parametrization of the rail head surface geometry and
the wheel thread geometry is conducted first and the wheel and rail contact
point is determined, with the help of the predefined simplified coordinate
system.
After the identification of the wheel-rail contact point, mathematically, Hertzian
contact theory is applied to calculate the contact area. Accordingly, for an
applied normal wheel load of 125kN, the contact area was found to be 118.3
mm2. Finite element models were also used to simulate the lateral and vertical
irregularities, with the help of computer software, ABAQUS. Eight finite element
models were analyzed for the study: four for lateral irregularity, three for
vertical irregularity, and one model for the tracks without irregularity.
When lateral irregularity is applied on the model the contact pressure on the rail
was found to be increasing as compared to the model simulating tracks without
irregularity, with a maximum increment of 33.34% for +30mm lateral irregularity.
However, contact area and normal contact force induced on the rail decreases
by 15.47%, for -8mm and +10mm lateral irregularity, and 15.17%, for +20mm
lateral irregularity, respectively.
Similarly, for the applied +30mm vertical irregularity the contact pressure
increases by 54.14%, however for +10mm vertical irregularity the contact
pressure decreases by 9.15%. Moreover, the +30mm vertical irregularity gives
the maximum contact area with a magnitude of 67.66 mm2.
Description
Keywords
(lateral and vertical) Track irregularity, Finite element modeling, Hertz contact theory, Parametrization