Fatigue Wear Analysis and Life Prediction of Rail Under Dry and Lubricated Wheel/Rail Contact Conditions
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Date
2017-06
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Addis Ababa University
Abstract
The rail is subjected to high contact stress of alternating magnitude due to wheel-rail frictional
rolling contact. Due to this the rail is prone to fatigue damage. This thesis paper addresses the
fatigue problem by developing the contact between wheel and rail and predicting the fatigue life
of the rail under dry and lubricated contact. Different values of friction coefficients are selected
to model the dry (µ=0.6) and lubricated (µ=0.2 and µ=0.05) wheel/rail contact conditions in this
study. The main objective of this is to study the effects of these varying friction coefficients on
the fatigue life of the rail, so that better maintenance schedule can be implemented to increase
the life of the rail. Analytical and numerical approaches are implemented in this thesis. The
analytical approach investigates the Normal contact problem and tangential contact problem at
the wheel/rail contact using the Hertz normal contact theory, Polach‟s tangential theories
respectively. The numerical approach is based on the static structural analysis of the wheel/rail
contact using ANSYS 15.0 commercial software. Three dimensional finite element method is
utilized to investigate the effect of friction on the wheel/rail contact stress and the fatigue life of
the rail. The fatigue life analysis is done using stress-life analyses approach. From the results
found it can be seen that the fatigue life of the rail induced under dry wheel/rail contact
conditions is minimum compared to the lubricated contact conditions. The fatigue life (in terms
of cycles to failure) is 3689.4 cycles under dry contact, and 37834 cycles under water lubricated
and 1.08e5 cycles under grease lubricated conditions. And the damage of the rail is higher under
dry contact condition compared to lubricated contact conditions. This thesis is applicable for the
Addis Ababa light rail operating system, in protecting the rail from fatigue failure. Managing the
friction coefficient on the rail is recommended on the results.
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Keywords
lubricated wheel/rail, Fatigue wear, dry wheel/rail contact