Aiming at the problem whether the stable operation of rotor system is influenced as installed displacement appears in one of ball bearings

a finite element model of the flexible rotor is established and the formula of the nonlinear force about misdisplacement installed bearing is derived. The numerical integral is employed to analyze the influence of installed displacement on the dynamic characteristics of the rotor system. Compared with the systems supported by bearings normally installed and ones with misdisplacement

it can be found that the installed displacement plays one of important factors on the stability of the rotor system. A certain misdisplacement makes the width of the system instability region narrower; if the displacement appears in x direction

the amplitude in x direction is smaller with the increasing installed displacement

while the amplitude in y direction does not change obviously. The analytic results show that the proper misdisplacement is beneficial for stable operation of the rotor system.