The effect of dynamic rail roll on the wheel–rail contact conditions

Simulation tools are now widely used to predict the dynamic behaviour of railway vehicles and they have been developed to include highly complex vehicle models which can represent non-linear wheel–rail contact and suspension characteristics. Less emphasis has so far been placed on the track models used in these simulations which have tended to be fairly simple linear representations of the track and subgrade although these can also contain significant discrete non-linearities. This paper first reviews the track models used in current railway vehicle dynamic software and identifies their main limitations. The particular focus of the work reported here is the rail roll degree of freedom (DOF) and its influence on the wheel–rail contact condition. The rigid body track model in the software tool VI-Rail powered by MSC Adams is modified to fully take into account rail roll in combination with the non-linear on-line contact algorithm. Various static and dynamic track cases are designed to test the hypothesis that rail roll may affect the contact condition. Results show the influence of the dynamic rail roll on the location of the contact between the wheel and rail and some analysis is made into the implications this may have on wear and rolling contact fatigue calculations among other applications.