Development and validation of a vertical vehicle-track interaction model

The vehicle-track interaction is related to most of the main problems in the railway field such as safety, comfort, design, maintenance, etc. The presence of track irregularities, added to the progressive increase of the running speed of vehicles and the axle load, enhances the exchanged wheel-rail forces, in particular in the vertical direction. For these reasons, many previous research works focused on the development of vertical vehicle-track interaction (VVTI) models, to study the dynamic behaviour of railway vehicles in the vertical direction. However, most of these models schematize simple single car-body railway vehicles. This paper presents in detail a new VVTI model able to describe both complex railway vehicles and complex track systems. The presented approach carefully takes into account track irregularities and relies on a fast integration method that guarantees a good compromise between efficiency and accuracy (a properly modified version of the Zhai model). The validation of the new strategy has been carried out by considering a complete Italian vehicle (the Metrobus Brescia, characterized by Jacobs type bogies) and by comparing the dynamic response of the metro under the effect of random irregularities with some experimental data. Consequently, this proposed approach can be considered a reliable solution for many other simulations and a base for future improvements, as the study of the lateral and longitudinal dynamic response and the wheel-rail wear.