Root Cause Analysis of Cracking in Shaft End and Coupling of a High-Power Generator

Failure analyses and root cause determination were carried out on the rotor of a high-power generator of gas–diesel dual fuel which presented cracking due to torsional fatigue in its end (region of section change and coupling), after 30,000 h of service. The generator of 307 MW–3000 rpm has a rotor...

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Autores principales:	Bilmes, Pablo David, Llorente, Carlos Luis, Echarri, Juan Manuel, Echarri, Tomás, Martínez, Ángel Joaquín, Zuzulich, José
Formato:	Articulo
Lenguaje:	Inglés
Publicado:	2018
Materias:	Ingeniería Failure analysis Fretting corrosion Fretting fatigue Torsional fatigue Generator rotor
Acceso en línea:	http://sedici.unlp.edu.ar/handle/10915/141096
Aporte de:	SEDICI (UNLP) de Universidad Nacional de La Plata

id	I19-R120-10915-141096
record_format	dspace
institution	Universidad Nacional de La Plata
institution_str	I-19
repository_str	R-120
collection	SEDICI (UNLP)
language	Inglés
topic	Ingeniería Failure analysis Fretting corrosion Fretting fatigue Torsional fatigue Generator rotor
spellingShingle	Ingeniería Failure analysis Fretting corrosion Fretting fatigue Torsional fatigue Generator rotor Bilmes, Pablo David Llorente, Carlos Luis Echarri, Juan Manuel Echarri, Tomás Martínez, Ángel Joaquín Zuzulich, José Root Cause Analysis of Cracking in Shaft End and Coupling of a High-Power Generator
topic_facet	Ingeniería Failure analysis Fretting corrosion Fretting fatigue Torsional fatigue Generator rotor
description	Failure analyses and root cause determination were carried out on the rotor of a high-power generator of gas–diesel dual fuel which presented cracking due to torsional fatigue in its end (region of section change and coupling), after 30,000 h of service. The generator of 307 MW–3000 rpm has a rotor (shaft of 400 mm O) manufactured in a proprietary steel grade equivalent to ASTM A470 type, Class 7 of high hardenability. It was reported that the equipment control system showed, in service, a high level of vibrations, not admissible for continuing the operation. First, and during the equipment shutdown for inspection, the presence of cracks, slant to the rotor shaft, was detected by means of visual inspection and dye penetrant test. The failure region corresponds to the zone of coupling–shaft joint, linked by means of fixation by interference, whereas the cracking spread on two fracture planes at 45° with respect to the rotor shaft. On this zone, where cracking started, a severe fretting corrosion damage was evidenced. The characterization and identification of present damage mechanisms were conducted through macrographic, fractographic, SEM, EDS, chemical analyses, and mechanical tests. It was recognized that from the damage by fretting corrosion, fatigue micro-cracks were produced that spread due to service tensions by a mechanism of fretting fatigue. The fatigue fracture propagation was developed into two orthogonal planes at 45° from the longitudinal shaft, which reveals an inversion in the loading condition, only justifiable by torsional vibrations that were assigned to a torsional resonance typical of the system dynamics. It was considered that the torsional vibrations cause micro-movements between components, promoting fretting corrosion and the subsequent fretting fatigue that finally induced the failure by high-cycle torsional fatigue with low-stress amplitude.
format	Articulo Articulo
author	Bilmes, Pablo David Llorente, Carlos Luis Echarri, Juan Manuel Echarri, Tomás Martínez, Ángel Joaquín Zuzulich, José
author_facet	Bilmes, Pablo David Llorente, Carlos Luis Echarri, Juan Manuel Echarri, Tomás Martínez, Ángel Joaquín Zuzulich, José
author_sort	Bilmes, Pablo David
title	Root Cause Analysis of Cracking in Shaft End and Coupling of a High-Power Generator
title_short	Root Cause Analysis of Cracking in Shaft End and Coupling of a High-Power Generator
title_full	Root Cause Analysis of Cracking in Shaft End and Coupling of a High-Power Generator
title_fullStr	Root Cause Analysis of Cracking in Shaft End and Coupling of a High-Power Generator
title_full_unstemmed	Root Cause Analysis of Cracking in Shaft End and Coupling of a High-Power Generator
title_sort	root cause analysis of cracking in shaft end and coupling of a high-power generator
publishDate	2018
url	http://sedici.unlp.edu.ar/handle/10915/141096
work_keys_str_mv	AT bilmespablodavid rootcauseanalysisofcrackinginshaftendandcouplingofahighpowergenerator AT llorentecarlosluis rootcauseanalysisofcrackinginshaftendandcouplingofahighpowergenerator AT echarrijuanmanuel rootcauseanalysisofcrackinginshaftendandcouplingofahighpowergenerator AT echarritomas rootcauseanalysisofcrackinginshaftendandcouplingofahighpowergenerator AT martinezangeljoaquin rootcauseanalysisofcrackinginshaftendandcouplingofahighpowergenerator AT zuzulichjose rootcauseanalysisofcrackinginshaftendandcouplingofahighpowergenerator
bdutipo_str	Repositorios
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Root Cause Analysis of Cracking in Shaft End and Coupling of a High-Power Generator

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