NONLINEAR VIBRATIONS OF THE "ROTOR – JOURNAL BEARINGS" SYSTEM

Abstract

The equations of motion of a rotor system mounted on journal bearings with a non-linear characteristic are solved by high-precision analytical methods. A new technique has been developed for solving nonlinear differential equations of motion of rotor systems mounted on journal bearings, taking into account nonlinearity of reaction forces of the lubricating layer. Algebraic systems of equations were obtained that allow us to determine amplitudes of nonlinear oscillations of the rotor and supports, and construct the amplitude-frequency characteristics of the system for varying parameters of the rotor, supports and fluid depending on the angular velocity of the rotor. The conditions and frequency intervals for the presence of self-oscillations of the rotor and supports were determined. The amplitude-frequency characteristics of the nonlinear oscillations of the rotor system are obtained, taking into account nonlinearity of characteristics of journal bearings. The optimal parameters depending on the size of the gap and the oil film, the mass of the supports, the fluids used as a lubricating layer in the journal bearing, with rigidity and damping coefficients, at which the magnitudes of the amplitudes of self-excited oscillations have optimal values, are obtained.

Keywords

• nonlinear vibrations
• harmonic balance method
• journal bearing
• sommerfeld’s hypothesis
• rotor system
• self-excited vibrations