Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Aspects of Crack Growth in Single-Crystal Nickel-Base Superalloys
Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
2017 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This Licentiate of Engineering thesis is a product of the results generated in the research project KME-702, which comprises modelling, microstructure investigations and material testing of cast nickel-base superalloys.

The main objective of this work is to model the fatigue crack propagation behaviour in single-crystal nickel-base superalloys. To achieve this, the influence of the crystal orientations on the cracking behaviour is assessed. The results show that the crystal orientation is strongly affecting the material response and must be accounted for. Furthermore, a linear elastic crack driving force parameter suitable for describing crystallographic cracking has been developed. This parameter is based on resolved anisotropic stress intensity factors and is able to predict the correct crystallographic cracking plane after a transition from a Mode I crack. Finally, a method to account for inelastic deformations in a linear elastic fracture mechanics context was investigated. A residual stress field is extracted from an uncracked finite-element model with a perfectly plastic material model and superimposed on the stress field from the cracked model with a linear elastic material model to account for the inelastic deformations during the determination of the crack driving force. The modelling work is validated by material testing on two different specimen geometries at different temperatures.

This Licentiate of Engineering thesis consists of two parts, where Part I gives an introduction and background to the research area, while Part II consists of three papers.

Abstract [sv]

Denna licentiatavhandling är en produkt av resultat som genererats i forskningsprojektet KME-702, och omfattar modellering, mikrostrukturundersökningar och materialprovning av gjutna nickelbaserade superlegeringar.

Huvudsyftet med detta arbete är att modellera sprickförloppet under utmattning i enkristallina nickelbaserade superlegeringar. För att uppnå detta har kristallorienteringens inverkan på sprickbeteendet utvärderats. Resultaten visar att kristallorienteringen har en stark inverkan på materialbeteendet, således måste hänsyn till denna tas. Dessutom har en linjär-elastisk sprickdrivkraftsparameter lämplig att beskriva kristallografisk sprickbildning utvecklats. Denna parameter är baserad på anisotropa spänningsintensitetsfaktorer på kristallplan och kan prediktera det korrekta kristallografiska sprickplanet efter övergång från Modus I spricka. Slutligen har undersökts en metod för att ta hand om inelastiska deformationer i en linjär-elastisk brottmekanikskontext. Ett restspänningsfält extraherades från en osprucken finita element modell med en ideal plastisk materialmodell. Denna överlagrades på spänningsfältet från den spruckna modellen, som analyserades med en linjär-elastisk materialmodell, för att ta hänsyn till de inelastiska deformationerna vid bestämning av sprickdrivkraften. Modelleringsarbetet validerades genom materialprovning på två olika provgeometrier vid olika temperaturer.

Licentiatavhandlingen består av två delar, där del I ger en introduktion och bakgrund till forskningsområdet medan del II består av tre papper.

Abstract [de]

Dieses Lizentiat der Ingenieurwissenschaften ist im Rahmen des Forschungsprojekts KME-702 entstanden, welches Modellierung, Mikrostrukturuntersuchungen und Materialtests von gegossenen nickelbasierten Superlegierungen umfasst.

Das Hauptziel dieser Arbeit ist die Modellierung der Ermüdungsrissausbreitung in einkristallinen nickelbasierten Superlegierungen. Um dieses zu erreichen, wurde der Einfluss der Kristallorientierungen auf das Rissverhalten untersucht. Die Ergebnisse zeigen, dass die Kristallorientierung das Materialverhalten stark beeinflusst und daher berücksichtigt werden muss. Darüber hinaus wurde ein linear elastischer Rissantriebskraftparameter entwickelt, der zum Beschreiben von kristallographischen Rissen geeignet ist. Dieser Parameter basiert auf aufgelösten anisotropen Spannungsintensitätsfaktoren und ist in der Lage, die korrekte kristallographische Rissebene nach einem Übergang von einem Modus I Riss vorherzusagen. Abschließend wird in einem linear-elastisch bruchmechanischen Kontext eine Methode untersucht, die nichtelastischen Deformationen bei der Bestimmung der Rissantriebskraft zu berücksichtigen. Dazu wird aus einem Finite-Elemente Modell, welches keinen Riss aufweist und mit einem perfekt plastischen Materialmodell beschrieben wird, das Restspannungsfeld extrahiert und dem Spannungsfeld überlagert, welches aus dem Modell mit Riss unter Verwendung eines linear elastischen Materialmodells erzeugt wurde. Die Modellierung wird durch Materialtests an zwei verschiedenen Probengeometrien bei unterschiedlichen Temperaturen validiert.

Dieses Lizentiat der Ingenieurwissenschaften besteht aus zwei Teilen, wobei Teil I eine Einführung und einen Hintergrund in das Forschungsgebiet gibt, während Teil II aus drei Forschungsartikeln besteht.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2017. , p. 26
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1794
National Category
Applied Mechanics
Identifiers
URN: urn:nbn:se:liu:diva-143058DOI: 10.3384/lic.diva-143058ISBN: 9789176853955 (print)OAI: oai:DiVA.org:liu-143058DiVA, id: diva2:1158365
Presentation
2017-12-15, A35, A-huset, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2017-11-20 Created: 2017-11-20 Last updated: 2017-11-20Bibliographically approved
List of papers
1. A FINITE ELEMENT STUDY OF THE EFFECT OF CRYSTAL ORIENTATION AND MISALIGNMENT ON THE CRACK DRIVING FORCE IN A SINGLE-CRYSTAL SUPERALLOY
Open this publication in new window or tab >>A FINITE ELEMENT STUDY OF THE EFFECT OF CRYSTAL ORIENTATION AND MISALIGNMENT ON THE CRACK DRIVING FORCE IN A SINGLE-CRYSTAL SUPERALLOY
Show others...
2016 (English)In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2016, VOL 7A, AMER SOC MECHANICAL ENGINEERS , 2016, no UNSP V07AT28A002Conference paper, Published paper (Refereed)
Abstract [en]

The elastic and plastic anisotropy of the single-crystal materials bring many difficulties in terms of modeling, evaluation and prediction of fatigue crack growth. In this paper a single-crystal material model has been adopted to a finite element-environment, which is paired with a crack growth tool. All simulations are performed in a three-dimensional context. This methodology makes it possible to analyze complex finite element-models, which are more application-near than traditional two-dimensional models. The influence of the crystal orientation, as well as the influence of misalignments of the crystal orientation due to the casting process are investigated. It is shown that both the crystal orientation and the misalignment from the ideal crystal orientation are important for the crack driving force. The realistic maximum limit of 10 degrees misalignment is considered. It can be seen that crack growth behavior is highly influenced by the misalignment. This knowledge is of great interest for the industry in order to evaluate the crack growth in single-crystal components more accurately.

Place, publisher, year, edition, pages
AMER SOC MECHANICAL ENGINEERS, 2016
National Category
Applied Mechanics
Identifiers
urn:nbn:se:liu:diva-132570 (URN)10.1115/GT2016-56305 (DOI)000385461600011 ()978-0-7918-4983-5 (ISBN)
Conference
ASME Turbo Expo: Turbine Technical Conference and Exposition
Available from: 2016-11-14 Created: 2016-11-14 Last updated: 2017-11-20
2. Three-Dimensional LEFM Prediction of Fatigue Crack Propagation in a Gas Turbine Disk Material at Component Near Conditions
Open this publication in new window or tab >>Three-Dimensional LEFM Prediction of Fatigue Crack Propagation in a Gas Turbine Disk Material at Component Near Conditions
Show others...
2016 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 4, article id 042506Article in journal (Refereed) Published
Abstract [en]

In this paper, the possibility to use linear elastic fracture mechanics (LEFM), with and without a superimposed residual stress field, to predict fatigue crack propagation in the gas turbine disk material Inconel 718 has been studied. A temperature of 400 degrees C and applied strain ranges corresponding to component near conditions have been considered. A three-dimensional crack propagation software was used for determining the stress intensity factors (SIFs) along the crack path. In the first approach, a linear elastic material behavior was used when analyzing the material response. The second approach extracts the residual stresses from an uncracked model with perfectly plastic material behavior after one loading cycle. As a benchmark, the investigated methods are compared to experimental tests, where the cyclic lifetimes were calculated by an integration of Paris law. When comparing the results, it can be concluded that the investigated approaches give good results, at least for longer cracks, even though plastic flow was taking place in the specimen. The pure linear elastic simulation overestimates the crack growth for all crack lengths and gives conservative results over all considered crack lengths. Noteworthy with this work is that the 3D-crack propagation could be predicted with the two considered methods in an LEFM context, although plastic flow was present in the specimens during the experiments.

Place, publisher, year, edition, pages
ASME, 2016
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:liu:diva-126240 (URN)10.1115/1.4031526 (DOI)000371125800020 ()
Note

Funding Agencies|Siemens Industrial Turbomachinery AB through Research Consortium of Materials Technology for Thermal Energy Processes [KME-702]; Swedish Energy Agency

Available from: 2016-03-21 Created: 2016-03-21 Last updated: 2017-11-30

Open Access in DiVA

Aspects of Crack Growth in Single-Crystal Nickel-Base Superalloys(1046 kB)31 downloads
File information
File name FULLTEXT01.pdfFile size 1046 kBChecksum SHA-512
8f571c6677b199722d13bdb9e7f4da5219616012e8cfeed084cf06384c593b8c7ddecef27c354832955788bda8740d666d9996e2208eb6eefaee1e0271e6be61
Type fulltextMimetype application/pdf
omslag(6338 kB)5 downloads
File information
File name COVER01.pdfFile size 6338 kBChecksum SHA-512
2ff9246ddff9efd75c04397f90a69ac2a168a49606c0afd85b73e1f5e0a5c9f24326cf05fa811bd6386c5a4aade6f167a250d5ff3e95a6ed74ea3b4134c1238a
Type coverMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Busse, Christian
By organisation
Solid MechanicsFaculty of Science & Engineering
Applied Mechanics

Search outside of DiVA

GoogleGoogle Scholar
Total: 31 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
isbn
urn-nbn

Altmetric score

doi
isbn
urn-nbn
Total: 181 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf