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Modal Structure Imbalance Fault Detection For Rotating Machines Open Access


Other title
rotating machines
subspace methods
fault detection
Type of item
Degree grantor
University of Alberta
Author or creator
Smith, Brendan S
Supervisor and department
Zhao, Qing (Electrical and Computer Engineering)
Examining committee member and department
Zhao, Qing (Electrical and Computer Engineering)
Jing, Yindi (Electrical and Computer Engineering)
Zuo, Ming (Mechanical Engineering)
Department of Electrical and Computer Engineering
Control Systems
Date accepted
Graduation date
Master of Science
Degree level
Fault detection methods have become an important tool in the prevention of safety and reliability issues for industrial rotating machines. Faults in these machines often develop progressively and are not easily observed under operating conditions until severe damage has occurred and further damage during the shut-down process is unavoidable. This type of fault is common in centrifugal separators, where nozzle plug imbalance faults occurring at supercritical operating speeds can lead to catastrophic failure during coast-down after the fault has progressed to the point that an alarm is triggered. This thesis presents a vibration-based subspace fault detection method intended for de- tecting rotor imbalance faults. This output-only method detects rotor imbalance faults using an asymptotic local approach that is sensitive to small changes in modal structure. The method was originally developed for stationary structures but is adapted here for constant- speed rotating systems. The faults of interest are static and dynamic rotor imbalances representative of the nozzle plug faults experienced by centrifugal separators. Two physical models of an idealized centrifugal separator are also presented and used to demonstrate the subspace fault detection method. The first is a mechanical simulation based on rigid body and flexible rotor dynamics derived from finite element analysis of a physical rotor. A physical laboratory bench model based on the simulated machine is also presented that allows the detection method to be demonstrated on a realistically complex system with limited instrumentation. Subspace fault detection results are presented for both machines using a range of static and dynamic imbalances of increasing severity. For comparison, results are also presented for two alternative detection methods for vibration faults that have received recent attention: sinusoidal synthesis and the Hilbert-Huang Transform. These results demonstrate that the subspace method produces superior results for imbalance faults, particularly in the case of dynamic imbalance.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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