Nonlinear investigation of the effect of primary suspension on the hunting stability of a rail wheelset

The mathematical model of a single railway wheelset moving with constant speed on a smooth, level, and tangential track is used to numerically investigate the nonlinear dynamics of the wheelset. Nonlinearities in the wheelset model include the nonlinear wheel-rail profile and the friction-creep characteristics of the wheel-rail contact geometry. Wheelset numerical simulations consider single-point and two-point wheel-rail contact scenarios. Sensitivity of the critical hunting velocity to primary stiffness and damping parameters is examined. Results of the lateral stability study indicate that the critical hunting velocity of the wheelset is most sensitive to the primary longitudinal and lateral stiffness. Methods involving semi-active and active control of the primary longitudinal stiffness are developed to raise the critical velocity of hunting. These approaches are seen to considerably increase the wheelset critical hunting velocity.