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Condition monitoring of gearboxes operating under fluctuating load conditions
Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2005.
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University of Pretoria
2013
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| _version_ | 1867613577899147264 |
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| access_status_str | Open Access |
| author2 | Heyns, P.S. (Philippus Stephanus) |
| author_browse | Heyns, P.S. (Philippus Stephanus) |
| author_facet | Heyns, P.S. (Philippus Stephanus) |
| collection | Thesis |
| dc_rights_str_mv | © 2005 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means,without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2005. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/25604 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:38:22.209Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/25604 Condition monitoring of gearboxes operating under fluctuating load conditions Heyns, P.S. (Philippus Stephanus) upetd@up.ac.za Stander, Cornelius Johannes Condition monitoring Modulation Fluctuating load Vibration Rotation domain averaging and normalisation Gearbox Order tracking UCTD Thesis (PhD (Mechanical Engineering))--University of Pretoria, 2005. Conventional gearbox vibration monitoring techniques are based on the assumption that changes in the measured structural response are caused by deterioration in the condition of the gears in the gearbox. However, this assumption is not valid under fluctuating load conditions, since the fluctuating load will amplitude modulate the measured vibration signal and cause the rotational speed of the system to change. In general monitoring of machines subject to fluctuating load conditions is dealt with by considering the constant load conditions on gearboxes or during free rotational tests. The need to monitor the condition of large gearboxes in mineral mining equipment has attracted greater interest in order to improve asset management. An inherent need for signal processing techniques, with the ability to indicate degradation in gear condition, under fluctuating load conditions exist. Such techniques should enable the online monitoring of gearboxes that operate under fluctuating load conditions. A continued flow of up to date information should consequently be available for asset and production management. With this research, a load demodulation normalisation procedure was developed to remove the modulation caused by fluctuating load conditions, which obscures the detection of an incipient gear fault conditions. A rotation domain averaging technique is implemented which combines the ability of computer order tracking and time domain averaging to suppress the spectral smearing effect caused by the fluctuation in speed, as well as to suppress the amplitude of the vibration which is not synchronous with the rotation of the gear shaft. It is demonstrated that the instantaneous angular speed of a gearbox shaft can be utilised to monitor the condition of the gear on the shaft. The instantaneous angular speed response measurement is less susceptible to phase distortion introduced by the transmission path when compared to conventional gearbox casing vibration measurements. A phase domain averaging approach was developed to overcome the phase distortion effect of the transmission path under fluctuating load conditions. The load demodulation normalisation and rotation domain averaging signal processing procedures were applied to both the conventional gearbox casing vibration and instantaneous angular speed measurements prior to the calculation of a smoothed pseudo Wigner-Ville distribution of the data. Statistical parameters such as the energy ratio were calculated from the distribution. These parameters could be monotonically trended under different load conditions to indicate the degradation of gear conditions. Mechanical and Aeronautical Engineering unrestricted 2013-09-06T22:37:37Z 2007-06-18 2013-09-06T22:37:37Z 2005-03-06 2005 2007-06-18 Thesis Stander CJ, 2005, Condition monitoring of gearboxes operating under fluctuating load conditions, PhD thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/25604 > H666/th http://hdl.handle.net/2263/25604 http://upetd.up.ac.za/thesis/available/etd-06182007-150441/ © 2005 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means,without the prior written permission of the University of Pretoria. application/pdf application/pdf application/pdf application/pdf University of Pretoria |
| spellingShingle | Condition monitoring Modulation Fluctuating load Vibration Rotation domain averaging and normalisation Gearbox Order tracking UCTD Condition monitoring of gearboxes operating under fluctuating load conditions |
| title | Condition monitoring of gearboxes operating under fluctuating load conditions |
| title_full | Condition monitoring of gearboxes operating under fluctuating load conditions |
| title_fullStr | Condition monitoring of gearboxes operating under fluctuating load conditions |
| title_full_unstemmed | Condition monitoring of gearboxes operating under fluctuating load conditions |
| title_short | Condition monitoring of gearboxes operating under fluctuating load conditions |
| title_sort | condition monitoring of gearboxes operating under fluctuating load conditions |
| topic | Condition monitoring Modulation Fluctuating load Vibration Rotation domain averaging and normalisation Gearbox Order tracking UCTD |
| url | http://hdl.handle.net/2263/25604 http://upetd.up.ac.za/thesis/available/etd-06182007-150441/ |