Opala M., Chudzikiewicz A., Drozdziel J., Sowiñski B.

Computer simulation has been proven in recent years to be one of the most efficient approaches to modeling of vibrations generated by a railway vehicle in different exploitation conditions. In this article the authors will focus on some basic aspects of lateral dynamics and corresponding low-frequency vibrations of the railway four-axle freight vehicle, utilizing the vehicle-track non-linear simulation model. The vehicle model is a 27 degrees of freedom multi-body system interacting with straight, irregular track. The parameters of the track represent different maintenance quality levels which are set according to UIC518 code. The parameters of the vehicle model are chosen to match a typical open freight car construction with normal and increased capacity level (increased load capacity in this case denotes load of 25T per axle). Lateral dynamics of a railway car is inseparably connected with the conditions of interaction between the wheels and rails, hence a special attention is paid to the contact conditions such as the actual shape of wheel and rail rolling surfaces, size of the contact area, interaction forces and resulting displacements. It has been found that the wear of rolling surfaces significantly influences the location of contact points and consequently changes the system dynamics by generating tangential forces which are different than forces acting between nominal profiles. It is known that tangential forces are the only factors to affect the lateral dynamic stability of a railway vehicle. Analysis of series of simulations enabled to formulate conclusions regarding running safety with reference to the track maintenance quality level and the level of profiles wear. For the simulation purposes different wheel profiles are taken into consideration: nominal and worn.