Numerical simulation of the frictional heat problem of subway brake discs considering variable friction coefficient and slope track

Abstract

Friction heating during braking may causes premature wear, thermal cracks and other damages which could weak the braking performance of subway vehicles. It is therefore important to determine the temperature field of the brake disc. The purpose of this paper is to propose a one-dimensional brake disc model and apply a new solution algorithm to obtain the temperature field of the brake disc, which is validated by the Renk Dynamometer test bench. The advantage of this numerical model is that the variable friction coefficient and slope are taken into account. The experimental dependency of the coefficient of friction on the velocity is approximated by interpolation and applied to the numerical model. The calculation is based on two cases of constant and velocity-dependent friction coefficient (COF) by using the method of lines (MOL), which has the advantage of shorter computation time and improved accuracy. The numerical results agree well with the experimental data. It was proved that disregarding the velocity dependence of the coefficient of friction, the maximum temperature during the entire braking process was underestimated by 15%. In addition, the subway vehicle braking on slope should decrease the speed limit appropriately to reduce the maximum temperature of the brake disc. This study can provide a theoretical basis for further fatigue study of brake discs.