Wheel/rail contact geometry parameters in regard to vehicle behaviour and their alteration with wear

This paper presents the progress of an attempt to identify wheel/rail contact geometry parameters related to vehicle behaviour. A so called “nonlinearity parameter” has recently been proposed with the aim to extend the commonly used characterisation of wheel/rail contact geometry by one equivalent conicity value. New investigations on a large amount of measured wheel and rail profiles show the typical alteration of the contact geometry parameters due to wear. The equivalent conicity increases while the nonlinearity parameter decreases with increasing vehicle mileage. This phenomenon can be explained by an increase of the contact conformity with wear. A new parameter for assessing the concentration of contact points during lateral wheelset displacement and thus indicating the wear spreading is proposed. The new parameters can support the assessment of contact geometry wheelset/track, the selection of wheel and rail profiles in simulations as well as the development of new wheel profiles.