The influence of surface roughness on the contact stiffness and the contact filter effect in nonlinear wheel–track interaction

• A wheel–track contact model including nonlinear contact filtering is presented.
• Predicted rail vibrations are compared to field measurements.
• A parametric study gives insights on roughness-induced contact nonlinearities.

A state-dependent contact model including nonlinear contact stiffness and nonlinear contact filtering is used to calculate contact forces and rail vibrations with a time-domain wheel–track interaction model. In the proposed method, the full three-dimensional contact geometry is reduced to a point contact in order to lower the computational cost and to reduce the amount of required input roughness-data. Green׳s functions including the linear dynamics of the wheel and the track are coupled with a point contact model, leading to a numerically efficient model for the wheel–track interaction. Nonlinear effects due to the shape and roughness of the wheel and the rail surfaces are included in the point contact model by pre-calculation of functions for the contact stiffness and contact filters. Numerical results are compared to field measurements of rail vibrations for passenger trains running at 200 kph on a ballast track. Moreover, the influence of vehicle pre-load and different degrees of roughness excitation on the resulting wheel–track interaction is studied by means of numerical predictions.