Optimal design of wheel profile for railway vehicles

Despite the advantages of modern designs of railway vehicles and their running gear and possibilities of introducing active wheelset steering control systems, many railroads and tram companies still use large numbers of old fashion vehicles. Dynamic performance, safety and maintenance costs strongly depend on the wheelset dynamics and, particularly, on the design of wheel and rail profiles. The present paper presents a design procedure for a wheel profile based on geometrical wheel/rail (w/r) contact characteristics, which uses a numerical optimization technique. The procedure has been developed by the Railway Engineering Group at Delft University of Technology. The formulated optimality criteria, which use requirements on railway track and wheelset, are related to stability of wheelset, cost efficiency of design and minimum wear of wheels and rails. The shape of a wheel profile has been varied during optimization. A new wheel profile is obtained for given target rolling radii difference (RRD) function and rail profile. Measurements of new and worn wheel and rail profiles have been used to define the target RRD curve. Finally, in order to check the w/r wear and safety requirements, dynamic simulations of a vehicle with obtained wheel profile have been performed using ADAMS/Rail software package. The proposed procedure has been applied to the design of a wheel profile for trams. Numerical results are presented and discussed.