HUNTING STABILITY OF HIGH-SPEED RAILWAY VEHICLE CONSIDERING THE ACTIONS OF STEADY AERODYNAMIC LOADS

With the enhancement of the speed of trains, the aerodynamic loads will deteriorate the hunting stability of motion of railway vehicles. There is seldom study on this problem. For this reason, the hunting stability of a high-speed railway vehicle is studied, considering the steady aerodynamic loads resulting from the actions of crosswind and airflow in the opposite advancing direction of train. The effects of variations of axle loads, creep coefficients, gravitational stiffness and angular stiffness due to actions of aerodynamic loads are taken into account. A mathematical model for hunting stability analysis of vehicle with 17 degrees of freedom is presented, in which the effects of aerodynamic loads are incorporated. A program based on the presented model is written and verified. And then, in different wind velocities, with cases for each component of aerodynamic force and moment acting individually and collectively being considered, the eigenvalues of hunting stability of vehicle are calculated. Furthermore, the critical velocities are obtained. It is shown that, aerodynamic loads can decrease the critical velocity of vehicle;the critical velocity decreases monotonously as the velocity of beam wind increases;the influences of pitch moment and lift force on critical velocity are larger than that of other components of aerodynamic loads.