Modeling of braking thermal effect for wheel-rail contact parameters

Abstract

The Hertzian contact parameters are evaluated by taking into account the increase in temperature of the wheel due to braking under a steady mechanical loading. An equivalent mechanical load is evolved by Finite Element Analysis (FEA) to produce the same effect of the mechanical and thermal loading. The values obtained by FEA and Hertz theory for steady mechanical loading as well as for equivalent mechanical loading are matching. The contact parameters are found to vary linearly with temperature and equations are developed to obtain these parameters under thermal and mechanical loading. For 146.3 °C temperature of wheel due to braking, the contact pressure is 941.3 MPa, shear stress is 378 MPa and for solo mechanical loading, they are 519.8 MPa and 191 MPa correspondingly. The area of contact patch has increased from 0.0652 m2 to 0.142 m2 by 2.2 times due to thermal effect.