THE INFLUENCE OF TRACK STIFFNESS DISTRIBUTION ON DYNAMIC BEHAVIOR OF TRACK TRANSITION

A model for dynamic analysis of the track stiffness distribution on the impact of track transition is developed with vehicle element and track element. The vehicle element model has a total of 26 DOFs, in which 10 DOFs are used to describe the vertical movement of the car body, and 16 DOFs are associated with the rail displacements. The track element includes rail, rail fastening and pad, ballast and subgrade. By means of Lagrange equation, numerical method for coupling the moving wheel and the rail with explicit formula is presented and the associated finite element formulations are obtained. As an application, influences of four kinds of transition patterns, i.e., abrupt change, step by step change and linear change as well as cosine change for track stiffness distributions in track transition, on dynamic behavior of the vehicle and the track are investigated. The computational results show that the transition pattern of the track stiffness has great influence on the dynamic behavior of the vehicle and the track and smoothing of the track stiffness distribution can significantly reduce the wheel/rail interaction forces and the vertical rail accelerations. From abating wheel/rail impact and improving traffic operation's point of view, the cosine change is the best, the linear change is the better and the abrupt change is the worst in the four kinds of the transition pattern of the track stiffness. However, the transition patterns of the track stiffness have nearly no influences on the vertical vehicle accelerations due to the excellent behaviour of vibration isolation resulting from the primary and the secondary suspension system of the vehicle.