A tool to estimate the wheel/rail contact and temperature rising under dry, wet and oily conditions

In this paper, finite element method (FEM) has been applied to evaluate the wheel/rail contact stress under different contact conditions. The elastic-plastic model coded in ANSYS/LS-DYNA includes a whole wheel, 680 mm of the canted rail, and sub-components of the track (railpads, sleepers, and ballast). The three values of friction coefficient 0.4, 0.2 and 0.07 have been chosen to model the dry, wet and oily environmental contacts, respectively. The high mechanical stresses exerted at the contact area will cause the temperature rise, which results in decreasing of the yield strength of the wheel/rail. The growth of temperature is a major source of the various microstructure changes that occurs on the rail surface, especially the formation of White Etching Layer (WEL). Therefore, a theoretical calculation of heat generation has also been implemented in the current research. The output data from the FEM models have been considered as the input for the theoretical thermal model to examine temperature rising on and beneath the rail surface. The combination of finite element method for contact stress and theoretical thermal method for temperature variation would provide a better understanding about wheel/rail contact under a variety of contact conditions (dry, wet, and oily). Various scenarios of damage mechanisms of rail have been considered in the paper. The obtained results from the model have revealed that the influence of environmental conditions on normal contact stress, pressure and contact area is negligible. In contrast, the magnitude of the Von-Mises stress and lateral and longitudinal stresses components can be significantly varied depending on the friction conditions. Moreover, the environmental condition has shown a major effect on the temperature rising at the contact zone.