Implementation of roughness and elastic-plastic behavior in a wheel-rail contact modeling for locomotive traction studies

All engineering surfaces are rough on the microscale, and the actual contact area is only a fraction of the geometrical area. Thus, it is essential to include roughness parameters in the model to simulate the real contact scenarios. An algorithm for the calculation of the realistic contact stresses with different surface roughness parameters considering elastic and plastic deformations and tribological behaviour at the wheel-rail interface was further developed and implemented in the wheel-rail coupling in the Gensys railway vehicle multibody software platform. Locomotive multibody model simulations using the developed wheel-rail coupling approach were performed under traction conditions that confirm the workability of the proposed algorithm by means of a comparison with results obtained with the original Extended CONTACT wheel-rail couplings under the same operational and simulation conditions. The results obtained allow an understanding of the difference in contact stress results between rough (Wheel Ra = 0.7 μm, Rail Ra = 0.4 μm) and ‘ideal’ (i.e., perfectly Smooth) contacts, and some limitations are stated in this paper.