Zili Li, Rolf Dollevoet, Jun Wu, Roumen Petrov, Jilt Sietsma
10th International Conference on Contact Mechanics (CM 2015)
Year: August 2015
Location: Colorado Spring, USA
finite element method, flash-temperature, frictional heat, wheel–rail contact
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The coupled mechanical–thermal behaviour of wheel and rail materials under rolling contact is studied to determine the temperature rise due to the frictional heat. The wheel–rail frictional rolling contact problem is solved using the three–dimensional finite element (FE) method. The FE model considers the wheel tread–rail top contact with partial-slip and converts the frictional energy into the heat as an attempt to estimate the temperature rise. Instead of assuming a global sliding velocity (a conventional premise in the field), the relative velocities of wheel-rail nodes in the contact patch are automatically taken into account in the coupled analysis (instantaneous micro-slip in contact points). Different levels of traction forces are studied which determine the amounts of frictional energy. The thermal properties are specified for the materials. Defining the contact regions of the wheel and rail as the thermal conduction boundary conditions, the frictional energy is converted into heat within the contact interface. After generating the energy flux, the heat conduction occurs in three dimensions both in the wheel and rail. A steady state implicit analysis is considered for the thermal solver, whereas the mechanical solver benefits from an explicit solution scheme. Distributions of stresses and temperatures in the contact patch are made available by analysing various loading conditions. Considering the formulations offered by three analytical methods in the literature, the results of rail temperature i.e. longitudinal distributions and peak values are calculated. Though they are much more simplified problems, these analytical methods are considered as the reference models (benchmark) for comparison. The same input data are used for all the reference models to enable the comparison. The outputs of numerical simulations are compared with the reference data, with discussion on similarities and discrepancies. The proposed model is able to calculate the flash-temperature in wheel and rail materials by dropping some of the conventional assumptions used in the analytical approaches.