Abstract
In order to further increase the travelling speed of the bullet trains, a deeper understanding of the hunting motion is required. Among various vibration modes associated to the snake-like movement of the railway vehicle, the hunting motion of the wheel axle requires the simplest analysis. However, even in such easy to understand case, analytical expressions for the natural frequency of hunting were obtained only for a geometrical model, which is unable to predict the damping effect induced by the contact of the wheels with the rails. In this work, in order to clarify the damping mechanism, related to the hunting motion of the wheel axle of a railway vehicle, a generalized dynamic model is proposed. Based on such model, analytic expressions for the damping coefficient and damped natural frequency are derived, without imposing restrictions on the ratio between the lateral and vertical creep coefficients. Influence of the travelling speed, wheel conicity, dimensionless mass of the wheel axle, ratio of the creep coefficients, ratio of the track span to the yawing diameter, etc., on the damping coefficient and damped natural frequency, is clarified.
