Assessment of methods for calculating contact pressure in wheel–rail/switch contact

Two models for wheel-rail rolling contact that are based on the half-space assumption are compared in this paper: Hertz and the non-Hertzian method implemented in the computer program CONTACT. These two models are further restricted by the assumption of linear-elastic material behaviour. Moreover, one elastic and one elastic-plastic finite element model of the contact are investigated with the commercial code ABAQUS. The finite element method is not limited by the half-space assumption or applicable to a linear-elastic material model only. The objective is to assess the four methods based on calculated contact pressure, contact patch size and penetration depth. Contact loads and contact locations, used as input data in the analysis, are taken from a vehicle dynamics simulation in the software GENSYS. The comparison is performed at a given cross-section in the crossing panel of a selected turnout design. To fulfil the requirements of the half-space assumption, the dimensions of the contact area must be small compared to the radii of curvature of the bodies in contact. On the selected cross-section, however, the half-space assumption does not hold since the smallest radius of rail curvature at the contact point is 13 mm, which is comparable to the largest semi-axis of the contact area. Nevertheless, it is found that the contact pressure distributions calculated using Hertz and CONTACT correlate well with those results obtained from the finite element method as long as no plastification of the material occurs.