University of Tasmania
Browse

File(s) under permanent embargo

Chaos in the unbalance response of journal bearings

journal contribution
posted on 2023-05-18, 22:45 authored by Brown, RD, Addison, P, Andrew ChanAndrew Chan
The behaviour of non-linear systems often yield unexpected phenomena which are extremely sensitive to initial conditions. The hydrodynamic journal bearing is a common machine element which is strongly nonlinear for large excursions within the clearance space. A simple model of a rigid journal, supported hydrodynamically using a short bearing theory is shown to behave chaotically when the rotating unbalance force exceeds the gravitational load. At these values of the force ratio the time history of the response is very sensitive to initial conditions and a spectral analysis demonstrates a significant broadening from the expected peak at the rotational frequency. A once per revolution sampling of the time history (Poincaré plot) revealed an apparent aperiodic pattern. An estimate of the fractal dimension using the Grasberger-Procaccia algorithm resulted in a lower bound of 2.15, a typical result for low dimensional systems with significant dissipative action. The required levels of unbalance are only an order of magnitude greater than acceptable levels for rotating machinery and thus could be achieved with in-service erosion or minor damage. The subsequent non-synchronous response could result in fatigue and potential shaft failure.

History

Publication title

Nonlinear Dynamics

Volume

5

Issue

4

Pagination

421-432

ISSN

0924-090X

Department/School

School of Engineering

Publisher

Kluwer Academic Publishers

Place of publication

Netherlands

Rights statement

Copyright 1994 Kluwer Academic Publishers

Repository Status

  • Restricted

Socio-economic Objectives

Civil construction design

Usage metrics

    University Of Tasmania

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC