Keywords: railway vehicle, vehicle-track interaction, non-elliptic contact, elastic wheelset, elastic rail, elastic multibody system.

The modelling of a railway vehicle as a multi-body system provides the simulation of a wide range of operational scenarios. However, some topics such as the wear require a refined modelling for a more accurate description of the contact area and the stress distribution within. For this refinement, the structural dynamics of the wheelsets and the rails are taken into account to provide a more accurate description of the relative kinematics of the wheel and rail. Also, a more detailed model of the wheel-rail contact, which can describe non-elliptic contact areas, is used. The entire vehicle-track model describes a passenger coach which is running on a straight track.

The main difficulty concerning the modelling of wheelsets and rails as elastic bodies is the description of the moving wheel-rail forces around the wheels and along the rails. By exploiting characteristics of the eigenmodes of rotational symmetric and prismatic structures in the cases of the wheelset and the rails, respectively, this problem can be solved in a simple and mathematical accurate way.

The wheel-rail contact is modelled as a force element acting between the wheelsets and the rails. In this contact model, wheel and rail are considered as elastic half-spaces. The relation between the stresses is described by the Boussinesq-Cerutti equations. Distributions of the normal and tangential stresses are discretised using a grid. The resulting equations are solved iteratively. Thereby, the description of non-elliptic contact patches is possible.

The simulation of the scenarios of undisturbed, centred running and hunting is performed for two different variants of the model, the one considering the wheelsets and the rails as rigid bodies, the other one taking the structural dynamics of wheelsets and rails into account. The comparison of the results shows that the structural elasticities of the wheelsets and the rails in fact have an impact on the wheel-rail contact. Already in the case of centred, undisturbed running of the wheelset, the shape of the contact area and of the distribution of the stresses and the dissipated power due to the friction are changed distinctly. The bending of the wheelset due to the load of the vehicle leads to an inclination of the wheel rim, which causes this change. The structural elasticities also affect the hunting motion of the wheelset. The motions of the wheelset are noticeably changed: larger lateral displacements of the wheelset occur arising from the structural deformations of the wheelsets and the rails. The change of the relative kinematics of wheel and rail arising from the structural deformations also has a strong impact on the distribution of the contact stresses.

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