Turbine blade crack detection using vibration testing methods

Turbine blades are the most common cause of failures in gas turbines. Failure modes are typically cracking from foreign object damage (FOD), high cycle stress (HCF), blade rubbing, degradation from erosion and corrosion. Fault detection of blades is important function in reducing blade related failu...

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Main Author:	Guai, Yeu Kae
Format:	Thesis
Language:	English
Published:	2009
Subjects:	TJ Mechanical engineering and machinery
Online Access:	http://eprints.utm.my/id/eprint/11299/6/GuaiYeuKaeMFKM2009.pdf
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id	my-utm-ep.11299
record_format	uketd_dc
spelling	my-utm-ep.112992017-09-13T07:54:55Z Turbine blade crack detection using vibration testing methods 2009-12 Guai, Yeu Kae TJ Mechanical engineering and machinery Turbine blades are the most common cause of failures in gas turbines. Failure modes are typically cracking from foreign object damage (FOD), high cycle stress (HCF), blade rubbing, degradation from erosion and corrosion. Fault detection of blades is important function in reducing blade related failures. This study involved the use of vibration analysis and dynamic testing of blades for failure detection. Current field inspections of blades are based on visual inspections only, and the intent here was to use impact testing of the blades during these inspections to determine cracked blade (from the vibration response). Vibration impact tests were undertaken using decommissioned turbine blades with and without cracks in the laboratory. Four common crack patterns were deliberately induced to the turbine blades to investigate changes in the blades normal mode response. Finite element analysis (FEA) of the blades was also undertaken. FEA results were correlated to experimental results and these results showed that each crack pattern was unique and significant changes were found in higher modes. Dynamic vibration analysis was also undertaken in a laboratory testrig fitted with rotating model straight blades. Vibration measurements were undertaken on a baseline test case and other test conditions where the blades had induced cracks. Steady state and transient vibration responses were obtained from the controlled tests. Vibration measurements were on the machine casing and on a blade (with an accelerometer surfaced mounted onto a rotating blade). Order tracking analysis and continuous wavelet analysis were performed to the measured data. Both techniques showed ability in detecting changes in vibration response on the blades and casing for blades with cracks. Results showed that significant changes were detected during transient analysis as compared to the steady state. Changes were noted in the vibration response corresponding to the machine running speed and blade passing frequencies. Changes in wavelet maps were however qualitative in nature, which suggested that more work need to be undertaken for cracks severity assessment using wavelet maps. 2009-12 Thesis http://eprints.utm.my/id/eprint/11299/ http://eprints.utm.my/id/eprint/11299/6/GuaiYeuKaeMFKM2009.pdf application/pdf en public masters Universiti Teknologi Malaysia, Faculty of Mechanical Engineering Faculty of Mechanical Engineering
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	TJ Mechanical engineering and machinery
spellingShingle	TJ Mechanical engineering and machinery Guai, Yeu Kae Turbine blade crack detection using vibration testing methods
description	Turbine blades are the most common cause of failures in gas turbines. Failure modes are typically cracking from foreign object damage (FOD), high cycle stress (HCF), blade rubbing, degradation from erosion and corrosion. Fault detection of blades is important function in reducing blade related failures. This study involved the use of vibration analysis and dynamic testing of blades for failure detection. Current field inspections of blades are based on visual inspections only, and the intent here was to use impact testing of the blades during these inspections to determine cracked blade (from the vibration response). Vibration impact tests were undertaken using decommissioned turbine blades with and without cracks in the laboratory. Four common crack patterns were deliberately induced to the turbine blades to investigate changes in the blades normal mode response. Finite element analysis (FEA) of the blades was also undertaken. FEA results were correlated to experimental results and these results showed that each crack pattern was unique and significant changes were found in higher modes. Dynamic vibration analysis was also undertaken in a laboratory testrig fitted with rotating model straight blades. Vibration measurements were undertaken on a baseline test case and other test conditions where the blades had induced cracks. Steady state and transient vibration responses were obtained from the controlled tests. Vibration measurements were on the machine casing and on a blade (with an accelerometer surfaced mounted onto a rotating blade). Order tracking analysis and continuous wavelet analysis were performed to the measured data. Both techniques showed ability in detecting changes in vibration response on the blades and casing for blades with cracks. Results showed that significant changes were detected during transient analysis as compared to the steady state. Changes were noted in the vibration response corresponding to the machine running speed and blade passing frequencies. Changes in wavelet maps were however qualitative in nature, which suggested that more work need to be undertaken for cracks severity assessment using wavelet maps.
format	Thesis
qualification_level	Master's degree
author	Guai, Yeu Kae
author_facet	Guai, Yeu Kae
author_sort	Guai, Yeu Kae
title	Turbine blade crack detection using vibration testing methods
title_short	Turbine blade crack detection using vibration testing methods
title_full	Turbine blade crack detection using vibration testing methods
title_fullStr	Turbine blade crack detection using vibration testing methods
title_full_unstemmed	Turbine blade crack detection using vibration testing methods
title_sort	turbine blade crack detection using vibration testing methods
granting_institution	Universiti Teknologi Malaysia, Faculty of Mechanical Engineering
granting_department	Faculty of Mechanical Engineering
publishDate	2009
url	http://eprints.utm.my/id/eprint/11299/6/GuaiYeuKaeMFKM2009.pdf
_version_	1747814837197471744

Turbine blade crack detection using vibration testing methods

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