Nonlinear dynamics of rub-impact on a rotor-rubber bearing system with the Stribeck friction model

Recent experiments on rotor-bearing systems have revealed that three or four different responses may occur when the rubbing occurs. In the present study, a mathematical model is established to investigate the dynamic characteristics of a rotor-rubber bearing system. The advantage of this model is demonstrated in the nonlinear stiffness of the rubber bearing and the Stribeck friction model, which generates friction force depending on the relative velocity. Through numerical calculation, the effects of rotational speed, the decaying factor, the stiffness coefficient, the nonlinear stiffness coefficient, and the imbalance coefficient on the responses of the rotor-rubber bearing system are investigated in detail using bifurcation diagrams, orbits of the rotor center, phase plane portraits, Poincaré maps, and amplitude spectra. The obtained numerical simulation results improve understanding on the dynamical characteristics of rub-impact on a rotor-rubber bearing system, such as periodic no-rubbing motion, periodic annular rubbing motion, period-multiplying motion, quasi-periodic motion, dry whip, and the jump phenomenon. These results can be effectively used to diagnose rub-impact faults and instabilities in such rotor systems. This study may contribute to further understanding on the nonlinear dynamical behavior of rub-impact on rotor-bearing systems with nonlinear stiffness from the rubber bearing and the Stribeck friction model.