Stability of rigid rotors supported by air foil bearings: Comparison of two fundamental approaches

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Abstract

High speed direct drive motors enable the use of Air Foil Bearings (AFB) in a wide range of applications due to the elimination of gear forces. Unfortunately, AFB supported rotors are lightly damped, and an accurate prediction of their Onset Speed of Instability (OSI) is therefore important. This paper compares two fundamental methods for predicting the OSI. One is based on a nonlinear time domain simulation and another is based on a linearised frequency domain method and a perturbation of the Reynolds equation. Both methods are based on equivalent models and should predict similar results. Significant discrepancies are observed leading to the question, is the classical frequency domain method sufficiently accurate? The discrepancies and possible explanations are discussed in detail. (C) 2016 Elsevier Ltd. All rights reserved.
Original languageEnglish
JournalJournal of Sound and Vibration
Volume381
Pages (from-to)179-191
ISSN0022-460x
DOIs
Publication statusPublished - 2016

Keywords

  • Air foil bearing
  • Rigid rotor
  • Transient simulation
  • Nonlinear analysis
  • Stability

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