  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.
