Study on Effect of Vehicle Behavior on Wheel Profile

Abstract

This paper presents the effect of vehicle hunting behavior on wheel profile. Contact force between wheel and rail is one of the most important indexes for evaluating characteristic hunting behavior. We conduct the numerical simulation which is based on the multibody dynamics and calculate contact point between wheel and rail exactly in order to figure out effect of vehicle hunting behavior on contact force. We use two types of wheel profile and compare conical profile with arc wheel profile. From this research, following conclusions were obtained. Critical speed of hunting of vehicle with conical profile decreases with increase of tread gradient. Critical speed of hunting of vehicle with arc wheel profile increases of tread curvature radius and decreases with increase of equivalent tread gradient. Adopting equivalent tread gradient, we can compare behavior of vehicles which have difference in wheel profile. Damping of lateral displacement is affected by lateral creep force. Damping ratio led by equation of motion depends on the amount of change of the contact angle difference for the lateral displacement of wheelset. Vehicle with arc wheel profile is attenuated faster than vehicle with conical profile. Radius and areas of contact ellipse of arc wheel profile hardly change when equivalent tread gradient is changed. On the other hand, Radius and areas of contact ellipse of conical profile change with changing tread gradient. Vehicle with conical profile has greater critical speed of hunting than vehicle with arc wheel profile when conical profile's areas of contact ellipse is small. Contact ellipse affects creep force using Kalker's creep theory.