Non-stationary processes of rotor/bearing system in bifurcations

Abstract

Non-stationary processes of a rotor/bearing system were dealt with by taking the rotating angular speed, increases or decreases linearly at different levels of acceleration, as control parameter. The stationary bifurcation diagrams show that the period doubling bifurcation or quasi-periodic bifurcation, corresponding to the system with larger or smaller level of mass imbalance, respectively, occurs smoothly as the control parameter is increased or decreased in stationary manner. Then, the non-stationary processes of these two types of bifurcation were investigated by constructions of the non-stationary bifurcation diagrams using non-stationary bifurcation map technique. In the non-stationary bifurcation diagrams, penetrations can be easily observed during the forward and reverse transitions, and their absolute values increase with that of accelerations in all cases. Jumps exist only in forward period doubling transitions, which indicate the quick increases of the amplitudes of motion. Time flows and orbit trajectories are also presented to illustrate the non-stationary transition processes visually.