Characteristic parameters of nonlinear wheel/rail contact geometry

The equivalent conicity is widely used to characterise the wheel/rail contact geometry; however, it does not consider the contact nonlinearity. There is a need for an improved but still simple description, which accounts for the most important effect of the contact nonlinearity on the running dynamics of railway vehicles. This article demonstrates the influence of the contact nonlinearities on the behaviour of railway vehicles at the stability limit and presents a description of wheel/rail contact geometry using two parameters. The proposed characteristic parameters are compared with the examples of wheelset/track pairs and the correlation between the proposed parameters and the vehicle behaviour presented.