Influence of track stiffness distribution on vehicle and track interactions in track transition

A model for dynamic analysis of the vehicle-track-subgrade coupling system was developed by utilizing the finite-element method. Based on the model, new types of vehicle and track elements are presented and their associated stiffness matrix, mass matrix, and damping matrix are formulated. Computational software is coded with Matlab. As an application example, influences of four kinds of transition patterns - abrupt change, step-by-step change, linear change, as well as cosine change for track stiffness distributions in track transitions - on dynamic behaviour of the vehicle and the track are investigated. The computational results show that the transition pattern of the track stiffness has primary influence on the dynamic behaviour of the vehicle and the track, and smoothing of the track stiffness distribution can significantly reduce the wheel-rail interaction forces and the rail vertical accelerations. From abating wheel-rail impact and improving traffic operation's point of view, the cosine change has the most effect, the linear change is somewhat effective and the abrupt change is the least effective for the four kinds of transition patterns of the track stiffness. However, the transition patterns of the track stiffness have essentially no influence on the vehicle vertical accelerations, due to the excellent behaviour of vibration isolation resulting from the primary and the secondary suspension systems of the vehicle.