Abstract:
The present thesis work is focused on evaluating the effect of temperature rise on the Hertzian contact parameters of wheel-rail contact of AALRT. The temperature rise is considered due to the breaking of the railway wheels and the maximum value is obtained as 146.3 0C. The wheels are also under the usual mechanical loading and the analysis is carried out for combined loading conditions to estimate the temperature effects. The variation in the contact pressure and contact surface area are estimated. As a result, the maximum shear stress and pressure are obtained as 941.24 MPa and 377.93 MPa as compared to 522.64 MPa and 191.11 MPa during structural loading. The Finite Element Analysis is conducted to reproduce the same Hertzian contact parameters by theoretical calculations. The difference in equivalent mechanical load and the combined (thermal and mechanical) load of FEA will give the corresponding mechanical load for the temperature rise due to braking. A direct relation has been observed between the temperature and the corresponding contact pressure and the contact area. Moreover, the area of contact patch under the combined loading condition (A = 0.142 m2) has increased 2.2 times that of in static loading condition only (A = 0.0652 m2). The relation for contact pressure has a good correlation between the results of FEA and Theoretical analysis. The FEA results have given a closely circular area of contact under thermal and mechanical loading conditions while the theoretical calculations are producing results for elliptical shape only. In conclusion, the result shows that the nature of the Hertzian contact patch and pressure between wheel and rail interface are strongly influenced by the temperature rising in wheel tread.