Nonlinear dynamics of a support-excited flexible rotor with hydrodynamic journal bearings

To determine the bifurcation types in a rotor-bearing system, it is required to find higher order derivatives of the bearing forces with respect to journal velocity and position. As closed-form expressions for journal bearing force are not generally available, Hopf bifurcation studies of rotor-bearing systems have been limited to simple geometries and cavitation models. To solve this problem, an alternative nonlinear coefficient-based method for representing the bearing force is presented in this study. A flexible rotor-bearing system is presented for which bearing force is modeled with linear and nonlinear dynamic coefficients. The proposed nonlinear coefficient-based model was found to be successful in predicting the bifurcation types of the system as well as predicting the system dynamics and trajectories at spin speeds below and above the threshold speed of instability.

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Stability of Flexible Rotor Supported on Journal Bearings

Vibration and Wear in High Speed Rotating Machinery ◽

10.1007/978-94-009-1914-3_32 ◽

1990 ◽

pp. 559-565

Author(s):

Faris Kaya

Keyword(s):

Journal Bearings ◽

Flexible Rotor

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Nonlinear Dynamics of a Rigid Rotor on Compliant Journal Bearings

IUTAM Symposium on Recent Developments in Non-linear Oscillations of Mechanical Systems - Solid Mechanics and Its Applications ◽

10.1007/978-94-011-4150-5_30 ◽

2000 ◽

pp. 301-309

Author(s):

B. L. Van De Vrande ◽

D. H. Van Campen

Keyword(s):

Nonlinear Dynamics ◽

Journal Bearings ◽

Rigid Rotor

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Nonlinear Simulation Analysis and Experiment of Fluid Plain Journal Bearing With Incompressible Fluid

Volume 5: 19th Biennial Conference on Mechanical Vibration and Noise, Parts A, B, and C ◽

10.1115/detc2003/vib-48415 ◽

2003 ◽

Author(s):

Katsuhisa Fujita ◽

Atsuhiko Shintani ◽

Koji Yoshioka ◽

Kouhei Okuno ◽

Hiroaki Tanaka ◽

...

Keyword(s):

Stability Analysis ◽

Incompressible Fluid ◽

Journal Bearing ◽

Simulation Analysis ◽

Journal Bearings ◽

Stable Region ◽

Flexible Rotor ◽

Nonlinear Simulation ◽

Fluid Forces ◽

The Stability

Recently, in many areas such as computers and information equipments etc., the fluid journal bearings are required to rotate at higher speed. To satisfy this requirement, the strictly stability analysis of the journal is indispensable. In this paper, we investigate the stability analysis of the dynamic behavior of the fluid plain journal bearing with an incompressible fluid considering the nonlinear terms of fluid forces. The stability analysis is examined by the numerical simulations on each model of a rigid rotor and a flexible rotor. The stable regions by nonlinear analysis are compared with the regions by classical linear analysis. Performing the nonlinear simulation analysis, it becomes clear that there is rather a stable region which amplitude does not grow up abruptly, and this phenomenon can not only be pointed out, but also is judged to be unstable by linear stable analysis. Finally, the experiment using actual bearings is performed and compared with the numerical results.

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