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Enriching balancing information using the unbalance covariance matrix

S Jiffri, S D Garvey, A I J Rix, Shakir Jiffri Orcid Logo

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, Volume: 223, Issue: 8, Pages: 1815 - 1826

Swansea University Author: Shakir Jiffri Orcid Logo

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DOI (Published version): 10.1243/09544062JMES1181

Abstract

Traditionally, rotor balancing is performed based only on vibration readings from either a balancing machine or from a machine in which the rotor is being balanced in-situ. These readings cannot reflect the complete state of unbalance in the rotor. The reason for this is that higher frequency modes...

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Published in: Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
ISSN: 0954-4062 2041-2983
Published: 2009
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URI: https://cronfa.swan.ac.uk/Record/cronfa36837
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spelling 2017-12-11T11:24:23.4811102 v2 36837 2017-11-20 Enriching balancing information using the unbalance covariance matrix 1d7a7d2a8f10ec98afed15a4b4b791c4 0000-0002-5570-5783 Shakir Jiffri Shakir Jiffri true false 2017-11-20 AERO Traditionally, rotor balancing is performed based only on vibration readings from either a balancing machine or from a machine in which the rotor is being balanced in-situ. These readings cannot reflect the complete state of unbalance in the rotor. The reason for this is that higher frequency modes do not make a significant contribution to response in any one operating condition. The resolution of measuring instrumentation is always limited and, as demands grow for ever-improved balance quality, this instrumentation struggles more and more with reducing signal-to-noise ratios. When balance corrections are made to a rotor based only on these vibration readings, the components of unbalance that tend to excite only the higher modes of the original configuration can make a significant contribution to response if the properties of the stator change.This article presents a novel approach to robust balancing. It relies on the use of additional information in the form of a rotor unbalance covariance matrix. In theory, this covariance matrix could be obtained if a large sample from the population of all rotors of this type could be tested in a very high-quality (and high-speed) balancing machine. This suggestion is impracticable in all real situations. However, it is entirely conceivable that modelling of the manufacturing processes used to create the rotor could deliver this covariance matrix. This article begins by illustrating how such a covariance matrix might be obtained from modelling and then goes on to explain how the information within the covariance matrix can be combined with a set of measurements from a specific rotor to provide an improved estimate of the actual state of unbalance on that rotor. Examples are included to demonstrate the proposed robust balancing method. Journal Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223 8 1815 1826 0954-4062 2041-2983 covariance, covariance matrix, unbalance, balancing, robust balancing 31 12 2009 2009-12-31 10.1243/09544062JMES1181 COLLEGE NANME Aerospace Engineering COLLEGE CODE AERO Swansea University 2017-12-11T11:24:23.4811102 2017-11-20T11:22:56.1696773 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Aerospace Engineering S Jiffri 1 S D Garvey 2 A I J Rix 3 Shakir Jiffri 0000-0002-5570-5783 4
title Enriching balancing information using the unbalance covariance matrix
spellingShingle Enriching balancing information using the unbalance covariance matrix
Shakir Jiffri
title_short Enriching balancing information using the unbalance covariance matrix
title_full Enriching balancing information using the unbalance covariance matrix
title_fullStr Enriching balancing information using the unbalance covariance matrix
title_full_unstemmed Enriching balancing information using the unbalance covariance matrix
title_sort Enriching balancing information using the unbalance covariance matrix
author_id_str_mv 1d7a7d2a8f10ec98afed15a4b4b791c4
author_id_fullname_str_mv 1d7a7d2a8f10ec98afed15a4b4b791c4_***_Shakir Jiffri
author Shakir Jiffri
author2 S Jiffri
S D Garvey
A I J Rix
Shakir Jiffri
format Journal article
container_title Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science
container_volume 223
container_issue 8
container_start_page 1815
publishDate 2009
institution Swansea University
issn 0954-4062
2041-2983
doi_str_mv 10.1243/09544062JMES1181
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Aerospace Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Aerospace Engineering
document_store_str 0
active_str 0
description Traditionally, rotor balancing is performed based only on vibration readings from either a balancing machine or from a machine in which the rotor is being balanced in-situ. These readings cannot reflect the complete state of unbalance in the rotor. The reason for this is that higher frequency modes do not make a significant contribution to response in any one operating condition. The resolution of measuring instrumentation is always limited and, as demands grow for ever-improved balance quality, this instrumentation struggles more and more with reducing signal-to-noise ratios. When balance corrections are made to a rotor based only on these vibration readings, the components of unbalance that tend to excite only the higher modes of the original configuration can make a significant contribution to response if the properties of the stator change.This article presents a novel approach to robust balancing. It relies on the use of additional information in the form of a rotor unbalance covariance matrix. In theory, this covariance matrix could be obtained if a large sample from the population of all rotors of this type could be tested in a very high-quality (and high-speed) balancing machine. This suggestion is impracticable in all real situations. However, it is entirely conceivable that modelling of the manufacturing processes used to create the rotor could deliver this covariance matrix. This article begins by illustrating how such a covariance matrix might be obtained from modelling and then goes on to explain how the information within the covariance matrix can be combined with a set of measurements from a specific rotor to provide an improved estimate of the actual state of unbalance on that rotor. Examples are included to demonstrate the proposed robust balancing method.
published_date 2009-12-31T03:46:12Z
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score 11.012678

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