DIFFERENT LATERAL DYNAMIC OPERATING-CONDITIONS OF A RAILWAY VEHICLE FITTED WITH INDEPENDENTLY ROTATING WHEELS

This paper reports theoretical investigations done by GEC ALSTHOM rela ted to the topic of railway vehicles with independently rotating wheel s (IRW). As a first step, 2 classes of model are developed successivel y for the conventional wheelset and for the IRW fitted wheelset. The f irst class of model describes 3 dimensional dynamics of the wheelset a nd takes into account the 2 specific non-linearities of railway system : contact geometry and creep forces dependency on creepages. Permanen t contact condition of the wheelset on the track is expressed by zero value of the 2 normal relatives velocities at the contact points, whic h leads to Lagrange equations with multipliers. Numerical solution by time integration of the differential algebraic set of equations involv es a specific processing. A second class of models results from linear izing contact geometry and contact forces relationships assuming small deviations around an equilibrium point. These models are restricted t o lateral dynamics. With help of these last class of models, specific behaviour of IRW wheelset is focused on. Analyze of the influence of c ertain 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 beh aviour exhibited by a full non-linear coach model is then performed, a s well as qualitative comparison with track tests results at high spee d from French National Railways (SNCF).