The bifurcation of the forced hunting motion and its interaction with the self-excited hunting motion

Forced hunting motion is a crucial and common nonlinear motion of the vehicle system, but its characteristic hasn’t been adequately investigated. In this paper, a theoretical solution for forced motion is proposed, and the bifurcation curve of forced motion is obtained. The effects of the excitation parameters are revealed, and the interaction between forced hunting motion and self-excited hunting motion is discussed. The results show that forced hunting motion has multiple limit cycles and bifurcation behaviour. The mode of the bifurcation curve can be transformed with the excitation parameters. Two kinds of motions are in competition with each other, and the self-excited motion can be suppressed to disappear. They also affect the bifurcation behaviours of each other, the forced hunting motion can bifurcate in advance, and the bifurcation of self-excited hunting motion can disappear. This work demonstrates that the forced motion has an inhibition effect on the self-excited motion. So, it is possible to reduce the wheelset hunting motion by prefabricating track irregularities or applying an active control with variable frequency and amplitude.