WEIGHT OPTIMIZATION OF RAILWAY FREIGHT BOGIE

Abstract

In this paper, the analytical model of a 6-DOF single railway-wheelset is used to mathematically examine the non-linear dynamics of the railway-wheelset. The non-linearities in the wheelset model has the non-linear wheel-rail profile, a non-linear creep model that considers creep coefficients and Kalker's coefficients as nonlinear which vary as a function of contact area between the wheel and rail, and a nonlinear suspension body force in y and z direction. The hunting motion is described as the lateral vibration of the wheelset due to the velocity, contact friction of the vehicle and the normal contact interactive forces. The results are influenced by some of the factors like conicity of the contact profile and the creep behavior of the contact area. Hunting or lateral vibration is one of the common instability which comes into existence when the rail vehicles are operating at high velocity of the vehicle. Hunting leads to difficulties in ride quality, then high wear to wheels and rails and even wheel derailment and finally wheel and rail are damaged. The complete study of the behavior of the hunting motion of the bogie and singlewheelset has been performed and this includes the study of bifurcation phenomenon, orbit plots and limit cycles. This work takes into account that the bogie is moving on a flat, regular and tangential track, in which the parts are rigid. Considering the origin of non-linearities in the bogie and wheelset are of the contact profile, the friction-creep characteristics, the wheel / rail contact geometry, and the non-linear bogie suspension characteristics. This thesis has taken both single-point wheelset contact and two-point wheelset wheel-rail contact conditions. The solutions of lateral and yaw stability change with the speed of the wheelset, these changes are explained from phase plot, bifurcation diagram and orbit plots. This procedure was done for various speeds to understand the behavior of the wheelset.