The partial and full rubbing of a flywheel rotor–bearing–stop system

The forced nonlinear vibration of a rotor rubbing with motion-limiting stops is investigated by means of numerical method. In the dynamic analysis, the large vibration of the multiple-degree-of-freedom rigid rotor is excited not only by the unbalance force but also by a harmonic excitation force as the simulation of low frequency disturbance and thus causes the rubbing between the inner wall of the hollow rotor and the stop which locates in the rotor. The simple Coulomb friction model and piecewise linear spring model are used to describe the contact between the rotating rotor and the stationary stop. The rotor to stop collision and rub happens occasionally on certain conditions. The forced vibration may become chaotic like when the collision and rubbing occurs. The stable partial rubbing motion shows that the stop is able to limit the vibration amplitude of the rotor which whirls violently at low frequency. With the increase of the amplitudes of the excitation, the partial rubbing will expand to full rubbing in which the rotor keeps contact with the stop. The full rubbing is periodic or quasi-periodic. It is supposed that the stop loses effectiveness when the full rubbing happens. The full rubbing takes place earlier as the friction factor becomes larger, and consequently the disturbance scope in which the stop works effectively becomes smaller.