Nonlinearity detection in hydraulic machines utilizing bispectral analysis

Higher order spectral analysis is one of the relatively more recent tools in signal processing used for detection and identification of higher harmonics in a signal. It is also acknowledged to be an effective tool for detecting nonlinear behavior in mechanical systems. In this study, vibration sourc...

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Main Author:	Mohamed Saeed, Somia Alfatih
Format:	Thesis
Published:	2013
Subjects:	TJ Mechanical engineering and machinery
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id	my-utm-ep.42178
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spelling	my-utm-ep.421782020-08-17T00:47:38Z Nonlinearity detection in hydraulic machines utilizing bispectral analysis 2013 Mohamed Saeed, Somia Alfatih TJ Mechanical engineering and machinery Higher order spectral analysis is one of the relatively more recent tools in signal processing used for detection and identification of higher harmonics in a signal. It is also acknowledged to be an effective tool for detecting nonlinear behavior in mechanical systems. In this study, vibration sources in piping system and in hydraulic machine which may have features of nonlinear behavior were investigated. An experimental study was undertaken to formulate a more sensitive and effective method using bispectral analysis to diagnose resonance in piping and cavitation in a centrifugal pump test facility. Data was obtained for normal and resonant conditions at different locations on the pipes, and analyzed using FFT and bispectrum methods. Bispectral analysis was shown to be a more effective tool in detecting coupled frequencies due to resonance. Cavitation was induced on the suction side of the pump. The cavitation signal was analyzed with and without induced cavitation conditions. It was observed that bispectral analysis could be used as an early indicator of cavitation with changes for severity of cavitation. Higher order spectral analysis was also undertaken on field data from compressor piping with suspected resonance. High frequencies random vibration was shown to be a good indicator of the excitation of one of the system component’s natural frequency. Field measurement results which required bump test confirmed resonance related fault. The results of bispectrum analysis showed the presence of nonlinearity in the spectrum due to the resonant condition without the need for a bump test. The findings suggested that bispectral analysis could be used as a diagnostic tool for machinery vibration related faults detection especially when plant shutdowns are not possible. 2013 Thesis http://eprints.utm.my/id/eprint/42178/ http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:78200 masters Universiti Teknologi Malaysia, Faculty of Mechanical Engineering Faculty of Mechanical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
topic	TJ Mechanical engineering and machinery
spellingShingle	TJ Mechanical engineering and machinery Mohamed Saeed, Somia Alfatih Nonlinearity detection in hydraulic machines utilizing bispectral analysis
description	Higher order spectral analysis is one of the relatively more recent tools in signal processing used for detection and identification of higher harmonics in a signal. It is also acknowledged to be an effective tool for detecting nonlinear behavior in mechanical systems. In this study, vibration sources in piping system and in hydraulic machine which may have features of nonlinear behavior were investigated. An experimental study was undertaken to formulate a more sensitive and effective method using bispectral analysis to diagnose resonance in piping and cavitation in a centrifugal pump test facility. Data was obtained for normal and resonant conditions at different locations on the pipes, and analyzed using FFT and bispectrum methods. Bispectral analysis was shown to be a more effective tool in detecting coupled frequencies due to resonance. Cavitation was induced on the suction side of the pump. The cavitation signal was analyzed with and without induced cavitation conditions. It was observed that bispectral analysis could be used as an early indicator of cavitation with changes for severity of cavitation. Higher order spectral analysis was also undertaken on field data from compressor piping with suspected resonance. High frequencies random vibration was shown to be a good indicator of the excitation of one of the system component’s natural frequency. Field measurement results which required bump test confirmed resonance related fault. The results of bispectrum analysis showed the presence of nonlinearity in the spectrum due to the resonant condition without the need for a bump test. The findings suggested that bispectral analysis could be used as a diagnostic tool for machinery vibration related faults detection especially when plant shutdowns are not possible.
format	Thesis
qualification_level	Master's degree
author	Mohamed Saeed, Somia Alfatih
author_facet	Mohamed Saeed, Somia Alfatih
author_sort	Mohamed Saeed, Somia Alfatih
title	Nonlinearity detection in hydraulic machines utilizing bispectral analysis
title_short	Nonlinearity detection in hydraulic machines utilizing bispectral analysis
title_full	Nonlinearity detection in hydraulic machines utilizing bispectral analysis
title_fullStr	Nonlinearity detection in hydraulic machines utilizing bispectral analysis
title_full_unstemmed	Nonlinearity detection in hydraulic machines utilizing bispectral analysis
title_sort	nonlinearity detection in hydraulic machines utilizing bispectral analysis
granting_institution	Universiti Teknologi Malaysia, Faculty of Mechanical Engineering
granting_department	Faculty of Mechanical Engineering
publishDate	2013
_version_	1747816708769316864

Nonlinearity detection in hydraulic machines utilizing bispectral analysis

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