The Temperature And Stress Distribution Of Wheel/Rail Due To Friction Based On FEM

With development of high-speed and heavy haul railways, rolling contact failure of wheel/rail, such as wear, flatting, checking and so on, become more and more serious. The temperature rise and thermal stress due to wheel/rail friction play an important role in such failure. So it' s necessary to study the temperature rise and thermal stress of wheel/rail to make an understanding of the failure mechanism of wheel/rail further. In this thesis the thermal effects of wheel/rail in rolling-sliding contact is analyzed with improved FEM codes TJ-2D and JCM-2D.In the analysis, firstly, the flux boundary condition is used to simulate the frictional heat resource between wheel and rail. The non-steady heat transfer between the contacting surfaces of the wheel/rail, heat-convection and radiation between the wheel/rail and the ambient were all taken into consideration. Therefore, a heat coupling model of the wheel/rail in rolling/sliding is put forward to calculate the frictional temperature rise in the wheel and rail. Secondly, after the temperature distribution of wheel/rail, due to friction, is calculated, substitute the thermal load with equivalent fictitious body force and boundary distributed force loaded on the nodes of the corresponding elements. The wheel-load is applied to the center of the wheel. If so, a coupling thermo-mechanical thermal -elastic plane stress model of wheel/rail in rolling-sliding contact was put forward to calculate the thermo-mechanical stress distribution of wheel/rail. The contact load between the wheel and rail can be modeled with Hertz pressure distribution or calculated with contact element method.This paper studies the temperature and stress distribution of wheel/rail due to friction in sliding and rolling cases. The effect of wear and sliding speed on the temperature and stress distribution in sliding case, the effect of wheel-load, creepage, friction coefficient and rolling speed in rolling case, and the effect ofsurface uneven on temperature distribution in both sliding and rolling cases are all analyzed in detail. Based on the results obtained, some conclusions are summarized. 1) The thermal effect exists in the thin layer of wheel/rail surface only, and lightens with the depth increasing. 2) Due to the surface material expansion caused by the frictional temperature, the thermo-mechanical stress level of wheel/rail subsurface is lower than the mechanical stress, and its depth increases with time. 3) The extension of contact patch due to wear can greatly affect the temperature and thermo-mechanical stress distribution in wear process. 4) The surface unevenness of wheel/rail can lead to temperature fluctuation that increases the thermal load of material. 5) The thermal effect of wheel/rail due to friction increase with the increasing of wheel-load, creepage and friction coefficient in rolling case. 6) The higher sliding speed leads to the higher thermal effect.