Evaluation of frictional suspension system performance in three-piece bogie by the multi-body-system approach

The nonlinear damping characteristics of friction wedges in the secondary suspension of a freight bogie are investigated considering unidirectional contact and non-smooth frictional forces. In the proposed MultiBody System model, each wedge has six Degrees of Freedom with corresponding inertial properties. The geometry of wedge, as well as, wedge angle, toe-in condition, and clearances between wedge/bolster and wedge/side frame are also considered in the modeling. The methodology for the identification of contact parameters is presented to achieve a smooth response and efficient numerical solutions. The response of the system with the proposed method is compared with the quasi-static methodology of wedge simulation and limitations of alternative methods are highlighted. The model is then applied to evaluate the effects of different design parameters of the wedge system on vertical and lateral response of the system.