Railway Dynamics with Curved Contact Patch

The wheel-rail contact modeling is of paramount importance for the dynamics of railway vehicles since it represents the interaction between the vehicle and the track. Although, in most cases, the contact generated occurs between convex surfaces which results in planar contact areas, the contact might take place in concave surfaces when negotiation sharp curves or due to the wear of profiles. In that cases, the resulting contact area is not planar. This work proposes a methodology to determine the shape of the contact patch in a curved surface, where the normal direction varies along its lateral direction. This method is based on a semi-Hertzian approach and discretizes the contact into longitudinal strips. The normal pressure distribution is computed in each strip separately using a non-Hertzian contact model and it is summed in a vector form to obtain the total normal force magnitude. Regarding the tangential forces, a look up table approach is considered. Finally, a trailer vehicle negotiating a curve is used to demonstrate the effectiveness of this methodology.