Research Information System
20th International Wheelset Conference, Illinois, United States Of America, 8 - 11 May 2023, pp.1-10, (Full Text)
Wheel flats is a major source of service and safety disruption
along railway tracks. At the minimum, wheel flats generate noise and vibrations.
As the sizes and the number of the wheel flats increase, the generated dynamic
impact forces as the wheel flats repeatedly ram onto the surface of the
railhead immediately create very high stresses at the wheel and rail contact
interfaces, wheel running surface and the wheel rim, axle bearings, axles, rail
head and the rail-tie bearing interface. The repeated and persistent occurrence
of high dynamic impact forces on the railhead, the frequency of which relates
to the train speed, the wheel diameter and the number of flats, advances the
number, the depth and the density of the cracks and defects that are already
forming along the railhead and the wheels, thereby gradually damaging the
running surfaces of both the rails and the wheels in time. The end result is
generally the fracture of the rail and/or the wheel, at one or many locations.
Through an investigative
collaboration, this paper presents the application of the Bezgin Method,
developed to estimate the highest values of dynamic impact forces on railway
tracks due to track and wheel roughness and the Bezgin – Kolukırık Equations K’B3
and K’B3,H that estimate the
highest values of the dynamic impact force factors due to wheel flats and compares
their estimates with the estimates of advanced numerical models developed by
SNCF Reseau. This study presents the variation of the effect of a wheel flat
with wheel diameter and the static axle force and relates the highest value of
the forces generated by a wheel flat with the length of the wheel flat. The
findings in this study can aid the railway authorities to establish thresholds
on wheel flats in relation to wheel diameter, train speed and static wheel
force, in addition to track and rolling stock stiffness and flat length.