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

D C Han,S H Choi,Y H Lee

doi:10.1155/s1023621x95000121

D C Han, S H Choi + Show 1 more

Open Access

https://doi.org/10.1155/s1023621x95000121

Copy DOI

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.

Highlights

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
From FIGUREs 8 and 9 it can be seen that differences between other models are increased as the bearing stiffness ratio is increased, but the difference ratio is almost independent of the beating stiffness ratio except for the 1st natural frequency of uniformly distributed model
The finite element approach is used in analyzing the influence of bearing width on the vibration characteristics of rotor-bearing systems where various models of bearing supports are used

Summary

Introduction

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. The bearings were simplified as point supported or uniformly distributed springs and dampers by Mourelatos and Parsons [1987]. Journal bearings are modelled as quadratically and trapezoidally distributed springs and dampers along the shaft. The stability limits of the rotating speed are calculated for an example rotor using two types of support model.

Results

Conclusion