Influence of the Track Model in the Simulation of the Vertical Vibration Behaviour of the Railway Vehicle Carbody

The paper analyses the influence of the track model in the simulation of the vertical vibration behaviour of the railway vehicle carbody. The study is developed based on two models of the vehicle-roadway system, respectively a "rigid track" model and an "elastic track" model. The "rigid track" model is a 7-degree-of-freedom model, which includes a rigid-flexible coupled vehicle model and a rigid track model. The "elastic track" model is a 15-degree-of-freedom model that includes the same rigid-flexible coupled model of the vehicle and an equivalent lumped-parameter model for the track. The evaluation of the vibration behaviour of the vehicle carbody is carried out for both models of the vehicle - track system, using the results obtained through numerical simulations regarding the frequency response functions, the power spectral density and the root mean square of the acceleration at three points relevant to the vibration of the carbody - one point positioned at the middle of the carbody and two points located above the bogies. The conclusions synthesized based on these results highlight, in general, the influence of the track model on the vibration behaviour of the carbody and, in particular, the influence of the track model on the dominant vibration modes and the vibration level of the carbody.