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International Journal of Rotating Machinery
Volume 1 (1995), Issue 3-4, Pages 277-284
http://dx.doi.org/10.1155/S1023621X95000121

Analysis of Vibration Characteristics for a Rotor-Bearing System Using Distributed Spring and Damper Model

Department of Mechanical Design and Production Engineering, College of Engineering, Seoul National University, San 56-1, Shinlim-Dong, Kwanak-Gu, Seoul 151-742, Korea

Copyright © 1995 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In this paper, we modelled the journal beatings as distributed springs and dampers to investigate the influence of beating width on the vibration characteristics of a rotor-beating system. A quadratic function is used as a shape function for hydrodynamic journal bearings. And a trapezoidally or a quadratically distributed model is used as a shape function for hydrostatic journal bearings. A finite element method is applied for analyzing the vibration characteristics of a rotor-bearing system.

Dimensionless governing equations are derived for a uniform rotor supported by two journal bearings, which are modelled as point supported or distributed springs and dampers. For these models, natural frequencies for various beating length ratios and stiffness ratios between the bearing and the shaft are calculated and compared with each other. Then the stability limits of a rotor supported by two cylindrical journal beatings are calculated for the point supported or distributed springs and dampers.