Abstract: Using poincare-like cell mapping method, the global characteristic and stability rule of nonlinear unbalanced bearing rotor systems are analyzed, the periodic solutions of this system and their domains of attraction in difference Poincare sections are given at the same time, the analysis for these domains of attraction shows the decrement law of perturbation for periodic solution will be different while the perturbation appears at the different position of limit cycle, and will change with the periodic movement of system by the same period. So the conclusion that the logarithmic decrement rule fitting for linear systems widely cannot be used in nonlinear unbalanced bearing rotor systems directly, therefore some reference are given to establish the new stability rule for nonlinear unbalanced bearing rotor system.

Key words: Bearing, Cell mapping, Nonlinear, Rotor