Thermal Fatigue Analysis and Evaluation of Wheel-Rail Contact under Braking Conditions

Abstract

Recently, reliability design considering the fatigue has been demanded for ensuring the driving safety for the high speed railway. In particular, the railway wheel and rail are subjected not only to mechanical load but also to high
thermal load due to frictional heat generated when the railway wheel contacts with the brake shoe during tread braking. As repetitive thermal load accelerates damage to the wheel surface, it leads to shorten the replacement cycle and increase the maintenance cost. Therefore, we expect to achieve the economic efficiency by using the wheel over the life expectancy while maintaining the structural health. Initial braking velocity is one of the main factors affecting the behaviors of contact surface between the wheel and rail. Therefore, it is necessary to evaluate the effect of thermal stress according to it. In this study, through the thermalmechanical analysis considering both mechanical load and thermal load caused frictional heat under braking conditions, thermal stress subjected to the contact surface between the railway wheel and rail was calculated. Based on these results, the thermal fatigue analysis was carried out to evaluate the safety under fatigue and predict the fatigue life.