Different Lateral Dynamic Operating Conditions of a Railway Vehicle Fitted with Independently Rotating Wheels.

Abstract

This paper reports theoretical investigations done by GEC ALSTHOM related to the topic of railway vehicles with independently rotating wheels (IRW). As a first step, 2 classes of model are developed successively for the conventional wheelset and for the IRW fitted wheelset. The first class of model describes 3 dimensional dynamics of the wheelset and takes into account the 2 specific non–linearities of railway system: contact geometry and creep forces dependency on creepages. Permanent contact condition of the wheelset on the track is expressed by zero value of the 2 normal relatives velocities at the contact points, which leads to Lagrange equations with multipliers. Numerical solution by time integration of the differential algebraic set of equations involves a specific processing. A second class of models results from linearizing contact geometry and contact forces relationships assuming small deviations around an equilibrium point. These models are restricted to lateral dynamics. With help of these last class of models, specific behaviour of IRW wheelset is focused on. Analyze of the influence of certain design parameters, notably an interwheel viscous damping effect, is conducted. Investigations are reported about the influence of IRW on the lateral dynamics of a full coach model. Confrontation with behaviour exhibited by a full non–linear coach model is then performed, as well as qualitative comparison with track tests results at high speed from French National Railways (SNCF).