D403 a Railway Wheelset Optimally Designed for Cold Press Fitting

Abstract

In the present paper. the study of the press fitting of railway wheels is studied with the aim to define the mechanical and physical parameters to be adopted in order to reduce as much as possible the damaging of both wheel and axle during repeated press fitting and wheel removals. The study has been performed in a theoretical way, through a new multi-objective optimisation method based on finite element analyses. The FEM model has been validated.Referring to an actual case, the parameters that influence the press fitting process have been determined. The parameters influence was related not only to the mechanical stresses into the structures of the wheel and the axle respectively, but also to the robustness of the design (sensitivity to the machining tolerances and to friction coeencient at the press fit surfaces). Sorne optimal solutions have been determined and compared (in terms of performances) with an actual ptoduction one. 'response surfaces' [14-16] have been determined to establish the mathematical relationships , between the design variables and the press fitting performance indices. Through the use of such response surfaces the design opti,misation has been performed.Much attention has been paid in finding those solutions which were optimal and robust, i.e. the selutions being insensitive to the uncontrolled variations affecting some parameters of the press shrinking process, as friction and