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  • 1.
    Gustafsson, David
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Lundström, Erik
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Correction: Corrigendum to High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions [Int. J. Fatigue 48 (2013) 178–186]2013In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 52, p. 157-157Article in journal (Refereed)
    Abstract [en]

    n/a

  • 2.
    Gustafsson, David
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Lundström, Erik
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions2013In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 48, p. 178-186Article in journal (Refereed)
    Abstract [en]

    Inconel 718 is a frequently used material for gas turbine applications at temperatures up to 650°C. For such components, the main load cycle is typically defined by the start-up and shut-down of the engine. In this main loading cycle, hold times at high temperature are commonly present in critical components. These high temperature hold times may greatly increase the fatigue crack growth rate with respect to the number of cycles unless other beneficial factors such as for example initial overloads are present. The latter can be caused by abnormal service conditions but can also occur on a more regular basis and are then typically observed in components with strong thermal transients during engine start-up. In this paper, focus has been placed on the effect of overloads on the hold time fatigue crack growth behaviour and its subsequent description. More specifically, crack propagation in Inconel 718 has been studied at the temperatures 550°C and 650°C with and without an overload at the start of the cycle. The effect of initial overloads was found to be substantial. A simple model for describing the effect of these loading conditions has also been developed based on the concept of the damaged zone, present around the crack tip. Irregular crack fronts and unbroken ligaments left on the fracture surfaces seen in complementary microscopy studies seem to support this approach. Furthermore, the stress state in front of a crack tip in a 2D model was investigated both with and without an initial overload. The results were related to the observed crack growth retardation behaviour found in the material testing.

  • 3.
    Lundström, Erik
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Modelling of fatigue crack propagation in Inconel 718 under hold time conditions2014Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis an investigation and modelling of the fatigue crack propagation in the nickel based superalloy Inconel 718, with a special emphasis on the effect of hold times, is presented. The modelling work has been concentrated on describing the hold time fatigue crack propagation by using the concept of a damaged zone in front of the crack tip, which is believed to have a lowered resistance against crack propagation.

    The modelling framework is built on physically motivated parameters, which are all easy to calibrate through one specially designed test type. Later evaluation through many experimental tests has also shown that the model is capable, within reasonable scatter level to predict, the hold time fatigue crack propagation for many different temperatures and loading conditions. Further evaluation of a complex flight spectrum, with the incorporation of crack closure within the model, was also predicted with a satisfying result.

    This thesis is divided into two parts. First, a background and a somewhat deeper discussion of the modelling of fatigue crack growth under hold time conditions is presented. The second part consists of ve appended papers, which describe the work completed so far in the project.

    List of papers
    1. High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions
    Open this publication in new window or tab >>High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions
    2013 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 48, p. 178-186Article in journal (Refereed) Published
    Abstract [en]

    Inconel 718 is a frequently used material for gas turbine applications at temperatures up to 650°C. For such components, the main load cycle is typically defined by the start-up and shut-down of the engine. In this main loading cycle, hold times at high temperature are commonly present in critical components. These high temperature hold times may greatly increase the fatigue crack growth rate with respect to the number of cycles unless other beneficial factors such as for example initial overloads are present. The latter can be caused by abnormal service conditions but can also occur on a more regular basis and are then typically observed in components with strong thermal transients during engine start-up. In this paper, focus has been placed on the effect of overloads on the hold time fatigue crack growth behaviour and its subsequent description. More specifically, crack propagation in Inconel 718 has been studied at the temperatures 550°C and 650°C with and without an overload at the start of the cycle. The effect of initial overloads was found to be substantial. A simple model for describing the effect of these loading conditions has also been developed based on the concept of the damaged zone, present around the crack tip. Irregular crack fronts and unbroken ligaments left on the fracture surfaces seen in complementary microscopy studies seem to support this approach. Furthermore, the stress state in front of a crack tip in a 2D model was investigated both with and without an initial overload. The results were related to the observed crack growth retardation behaviour found in the material testing.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    Nickel-base superalloys, fatigue crack propagation, Inconel 718, hold times, grain boundary embrittlement, crack propagation modelling, Finite Element modelling
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-85931 (URN)10.1016/j.ijfatigue.2012.10.018 (DOI)000315617500020 ()
    Available from: 2013-03-13 Created: 2012-12-03 Last updated: 2017-12-07Bibliographically approved
    2. Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions
    Open this publication in new window or tab >>Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions
    2013 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 52, p. 124-130Article in journal (Refereed) Published
    Abstract [en]

    Inconel 718 is a frequently used material for gas turbine applications at temperatures up to 650 °C. The main load cycle for such components is typically defined by the start-up and shut-down of the engine. It generally includes hold times at high temperatures, which have been found to have a potential for greatly increasing the fatigue crack growth rate with respect to the number of load cycles. However, these effects may be totally or partly cancelled by other load features, such as overloads or blocks of continuous cyclic loading, and the actual crack propagation rate will therefore depend on the totality of features encompassed by the load cycle. It has previously been shown that the increased crack growth rate found in hold time experiments can be associated with a damage evolution, where the latter is not only responsible for the rapid intergranular crack propagation during the actual hold times, but also for the increased crack growth during the load reversals. In this paper, modelling of the hold time fatigue crack growth behaviour of Inconel 718 has been carried out, using the concept of a damaged zone as the basis for the treatment. With this conceptually simple and partly novel approach, it is shown that good agreement with experimental results can be found.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    Nickel-base superalloys, fatigue crack propagation, Inconel 718, hold times, grain boundary embrittlement, crack propagation modelling
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-85933 (URN)10.1016/j.ijfatigue.2013.03.004 (DOI)000318831300013 ()
    Available from: 2012-12-03 Created: 2012-12-03 Last updated: 2017-12-07Bibliographically approved
    3. A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions
    Open this publication in new window or tab >>A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions
    2014 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 118, p. 17-30Article in journal (Refereed) Published
    Abstract [en]

    Modelling of high temperature fatigue crack growth in Inconel 718 under the interaction of fast cyclic loading and hold times at maximum load has been conducted. A model, based on the concept of a damaged zone in front of the crack tip has been applied for three different temperatures, 550, 600 and 650 ◦C, with good agreement for both calibration and validation tests. A statistical evaluation of 22 tests in total was also conducted, which shows that the developed model gives a reasonable scatter factor at a probability of failure of 0.1 %.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Fatigue crack propagation, Inconel 718, Hold time effects, Crack growth modelling, Statistics
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-104809 (URN)10.1016/j.engfracmech.2014.02.005 (DOI)000334819600002 ()
    Available from: 2014-02-27 Created: 2014-02-27 Last updated: 2017-12-05Bibliographically approved
    4. Modelling of fatigue crack growth in Inconel 718 under hold time conditions - application to a flight spectrum
    Open this publication in new window or tab >>Modelling of fatigue crack growth in Inconel 718 under hold time conditions - application to a flight spectrum
    2014 (English)In: Advanced Materials Research, ISSN 1662-8985, Vol. 891-892, p. 759-764Article in journal (Refereed) Published
    Abstract [en]

    Gas turbine operating cycles at high temperatures often consist of load reversals mixed with hold times; the latter occurring either as cruise for aero engines or at continuous power output for land based turbines, but also at low frequency loading conditions, e.g. slow “ramp up” of engine thrust. The hold time conditions cause the crack to grow by intergranular fracture due to material damage near the crack tip, thus rapidly increasing the crack growth rate. Since the damaged zone will affect the crack propagation rate due to cyclic loadings as well, the complete load history of a component therefore has to be considered. The crack propagation model presented in this paper is based on the damaged zone concept, and considers the history effect in the form of damaged zone build up during hold times, and subsequent destruction as the crack propagates onwards by rapidly applied load reversals. By incorporating crack closure for handling different R-values, an aero engine component spectrum is evaluated for a surface crack at 550 C. The result shows a good correlation to model simulation, despite the complexity of the load spectrum.

    Place, publisher, year, edition, pages
    Trans Tech Publications Inc., 2014
    Keywords
    Fatigue crack propagation, Inconel 718, Hold time effects, Crack growth modelling
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-104812 (URN)10.4028/www.scientific.net/AMR.891-892.759 (DOI)000337767700118 ()
    Available from: 2014-02-27 Created: 2014-02-27 Last updated: 2016-05-18Bibliographically approved
    5. Evaluation and prediction of crack length in a Ni-based superalloy for sustained loading
    Open this publication in new window or tab >>Evaluation and prediction of crack length in a Ni-based superalloy for sustained loading
    2014 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Crack length evaluations for sustained loading have been conducted on Inconel 718 surface crack specimens for 550 and 650 ◦C. Hold times, e.g. slow ramp up of engine thrust, sustained load as continuous power output for stationary gas turbines or as cruise for aero engines, have been seen to result in material damage at the crack tip, causing the crack to grow by intergranular fracture and resulting in a strong increase of the crack growth rate. Here, sustained load tests as well as specially designed hold time tests are used to measure crack length and the size of the damaged zone (material damage) in front of the crack tip by comparing potential drop (PD) predictions with visible post-mortem beach marks on the fracture surface. Fracture surfaces were also investigated with scanning electron microscope (SEM), showing what the damaged zone most likely consists of. In addition, by applying a crack propagation model based on the damaged zone concept, crack length and damaged zone evaluations were conducted. The results show that the damaged zone must be taken into consideration, when evaluating post-mortem fracture surfaces if the test has included hold time loads, both when setting up post-mortem calibration curves and when evaluating crack propagation models.

    Keywords
    Fatigue crack propagation, Inconel 718, Sustained load, Hold time effects, Crack length evaluation
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-104813 (URN)
    Available from: 2014-02-27 Created: 2014-02-27 Last updated: 2014-02-27Bibliographically approved
  • 4.
    Lundström, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Evaluation and prediction of crack length in a Ni-based superalloy for sustained loading2014Manuscript (preprint) (Other academic)
    Abstract [en]

    Crack length evaluations for sustained loading have been conducted on Inconel 718 surface crack specimens for 550 and 650 ◦C. Hold times, e.g. slow ramp up of engine thrust, sustained load as continuous power output for stationary gas turbines or as cruise for aero engines, have been seen to result in material damage at the crack tip, causing the crack to grow by intergranular fracture and resulting in a strong increase of the crack growth rate. Here, sustained load tests as well as specially designed hold time tests are used to measure crack length and the size of the damaged zone (material damage) in front of the crack tip by comparing potential drop (PD) predictions with visible post-mortem beach marks on the fracture surface. Fracture surfaces were also investigated with scanning electron microscope (SEM), showing what the damaged zone most likely consists of. In addition, by applying a crack propagation model based on the damaged zone concept, crack length and damaged zone evaluations were conducted. The results show that the damaged zone must be taken into consideration, when evaluating post-mortem fracture surfaces if the test has included hold time loads, both when setting up post-mortem calibration curves and when evaluating crack propagation models.

  • 5.
    Lundström, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Gustafsson, David
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Månsson, T.
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions2014In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 118, p. 17-30Article in journal (Refereed)
    Abstract [en]

    Modelling of high temperature fatigue crack growth in Inconel 718 under the interaction of fast cyclic loading and hold times at maximum load has been conducted. A model, based on the concept of a damaged zone in front of the crack tip has been applied for three different temperatures, 550, 600 and 650 ◦C, with good agreement for both calibration and validation tests. A statistical evaluation of 22 tests in total was also conducted, which shows that the developed model gives a reasonable scatter factor at a probability of failure of 0.1 %.

  • 6.
    Lundström, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Månsson, Tomas
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Gustafsson, David
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Modelling of fatigue crack growth in Inconel 718 under hold time conditions - application to a flight spectrum2014In: Advanced Materials Research, ISSN 1662-8985, Vol. 891-892, p. 759-764Article in journal (Refereed)
    Abstract [en]

    Gas turbine operating cycles at high temperatures often consist of load reversals mixed with hold times; the latter occurring either as cruise for aero engines or at continuous power output for land based turbines, but also at low frequency loading conditions, e.g. slow “ramp up” of engine thrust. The hold time conditions cause the crack to grow by intergranular fracture due to material damage near the crack tip, thus rapidly increasing the crack growth rate. Since the damaged zone will affect the crack propagation rate due to cyclic loadings as well, the complete load history of a component therefore has to be considered. The crack propagation model presented in this paper is based on the damaged zone concept, and considers the history effect in the form of damaged zone build up during hold times, and subsequent destruction as the crack propagates onwards by rapidly applied load reversals. By incorporating crack closure for handling different R-values, an aero engine component spectrum is evaluated for a surface crack at 550 C. The result shows a good correlation to model simulation, despite the complexity of the load spectrum.

  • 7.
    Storgärds, Erik
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    High Temperature Fatigue Crack Growth in a Ni-based Superalloy: Modelling Including the Interaction of Dwell Times2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Safe life of gas turbines is always of major concern for manufacturers in order to ensure passenger safety and stable continuous power output. An increasing amount of resources have been put into research and development to assure that all safety aspects are covered in the design of new turbines and to ensure that enough frequent service intervals are scheduled to avoid complications. Many of these issues require good knowledge of material properties and of how to use these in the design process. Some of these relate to fatigue which is of major concern in all parts of a development programme. However, while some fatigue problems have been extensively studied, some have not. One example is crack growth with influence of dwell times at elevated temperature in combination with cyclic loading. Such loading conditions have been shown to give a different cracking behaviour compared to rapid cyclic loading, increasing the growth rate significantly with respect to the number of load cycles. Improved models for predicting this behaviour is therefore of major interest for gas turbine manufacturers, and could substantially increase the reliability. As a result, more research is needed in order  solve these problems.

    The work presented in this dissertation has focused on how to predict life under the above-mentioned circumstances. The materials used in high temperature gas turbine applications are often nickel-based superalloys, and in this work the most common one, Inconel 718, has been studied. Mechanical experiments have been performed under operation like conditions in order to receive material data for the subsequent modelling work. The modelling approach was chosen such that the underlying physics of the dwell time cracking have been incorporated on a phenomenological basis, creating a model which can be physically motivated as well as used for industrial applications. The main feature of the modelling work has been to track material damage which is received from dwell times, how this interacts with cyclic loading and how it affects the crack growth rate, thus creating a load history dependent model.

    The outcome of this work has resulted in a model which is both easy to use and which has shown to give good correlation to available experimental data. Key components such as calibration for cheap and easy parameter determination, validation on complex engine spectra loadings, three dimensional crack growth, overload influences, material scatter, thermo-mechanical fatigue crack growth and the impact of high cycle fatigue loadings, are all covered in the presented work, both as experimental findings and as continuous development of the modelling concept.

    The dissertation consists of two parts. In the first an introduction with the theory and background to crack growth with dwell times is given, while the second part consists of 10 papers.

    List of papers
    1. High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions
    Open this publication in new window or tab >>High temperature fatigue crack growth behaviour of Inconel 718 under hold time and overload conditions
    2013 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 48, p. 178-186Article in journal (Refereed) Published
    Abstract [en]

    Inconel 718 is a frequently used material for gas turbine applications at temperatures up to 650°C. For such components, the main load cycle is typically defined by the start-up and shut-down of the engine. In this main loading cycle, hold times at high temperature are commonly present in critical components. These high temperature hold times may greatly increase the fatigue crack growth rate with respect to the number of cycles unless other beneficial factors such as for example initial overloads are present. The latter can be caused by abnormal service conditions but can also occur on a more regular basis and are then typically observed in components with strong thermal transients during engine start-up. In this paper, focus has been placed on the effect of overloads on the hold time fatigue crack growth behaviour and its subsequent description. More specifically, crack propagation in Inconel 718 has been studied at the temperatures 550°C and 650°C with and without an overload at the start of the cycle. The effect of initial overloads was found to be substantial. A simple model for describing the effect of these loading conditions has also been developed based on the concept of the damaged zone, present around the crack tip. Irregular crack fronts and unbroken ligaments left on the fracture surfaces seen in complementary microscopy studies seem to support this approach. Furthermore, the stress state in front of a crack tip in a 2D model was investigated both with and without an initial overload. The results were related to the observed crack growth retardation behaviour found in the material testing.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    Nickel-base superalloys, fatigue crack propagation, Inconel 718, hold times, grain boundary embrittlement, crack propagation modelling, Finite Element modelling
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-85931 (URN)10.1016/j.ijfatigue.2012.10.018 (DOI)000315617500020 ()
    Available from: 2013-03-13 Created: 2012-12-03 Last updated: 2017-12-07Bibliographically approved
    2. Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions
    Open this publication in new window or tab >>Modelling of high temperature fatigue crack growth in Inconel 718 under hold time conditions
    2013 (English)In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 52, p. 124-130Article in journal (Refereed) Published
    Abstract [en]

    Inconel 718 is a frequently used material for gas turbine applications at temperatures up to 650 °C. The main load cycle for such components is typically defined by the start-up and shut-down of the engine. It generally includes hold times at high temperatures, which have been found to have a potential for greatly increasing the fatigue crack growth rate with respect to the number of load cycles. However, these effects may be totally or partly cancelled by other load features, such as overloads or blocks of continuous cyclic loading, and the actual crack propagation rate will therefore depend on the totality of features encompassed by the load cycle. It has previously been shown that the increased crack growth rate found in hold time experiments can be associated with a damage evolution, where the latter is not only responsible for the rapid intergranular crack propagation during the actual hold times, but also for the increased crack growth during the load reversals. In this paper, modelling of the hold time fatigue crack growth behaviour of Inconel 718 has been carried out, using the concept of a damaged zone as the basis for the treatment. With this conceptually simple and partly novel approach, it is shown that good agreement with experimental results can be found.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    Nickel-base superalloys, fatigue crack propagation, Inconel 718, hold times, grain boundary embrittlement, crack propagation modelling
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-85933 (URN)10.1016/j.ijfatigue.2013.03.004 (DOI)000318831300013 ()
    Available from: 2012-12-03 Created: 2012-12-03 Last updated: 2017-12-07Bibliographically approved
    3. A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions
    Open this publication in new window or tab >>A load history dependent model for fatigue crack propagation in Inconel 718 under hold time conditions
    2014 (English)In: Engineering Fracture Mechanics, ISSN 0013-7944, E-ISSN 1873-7315, Vol. 118, p. 17-30Article in journal (Refereed) Published
    Abstract [en]

    Modelling of high temperature fatigue crack growth in Inconel 718 under the interaction of fast cyclic loading and hold times at maximum load has been conducted. A model, based on the concept of a damaged zone in front of the crack tip has been applied for three different temperatures, 550, 600 and 650 ◦C, with good agreement for both calibration and validation tests. A statistical evaluation of 22 tests in total was also conducted, which shows that the developed model gives a reasonable scatter factor at a probability of failure of 0.1 %.

    Place, publisher, year, edition, pages
    Elsevier, 2014
    Keywords
    Fatigue crack propagation, Inconel 718, Hold time effects, Crack growth modelling, Statistics
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-104809 (URN)10.1016/j.engfracmech.2014.02.005 (DOI)000334819600002 ()
    Available from: 2014-02-27 Created: 2014-02-27 Last updated: 2017-12-05Bibliographically approved
    4. Modelling of fatigue crack growth in Inconel 718 under hold time conditions - application to a flight spectrum
    Open this publication in new window or tab >>Modelling of fatigue crack growth in Inconel 718 under hold time conditions - application to a flight spectrum
    2014 (English)In: Advanced Materials Research, ISSN 1662-8985, Vol. 891-892, p. 759-764Article in journal (Refereed) Published
    Abstract [en]

    Gas turbine operating cycles at high temperatures often consist of load reversals mixed with hold times; the latter occurring either as cruise for aero engines or at continuous power output for land based turbines, but also at low frequency loading conditions, e.g. slow “ramp up” of engine thrust. The hold time conditions cause the crack to grow by intergranular fracture due to material damage near the crack tip, thus rapidly increasing the crack growth rate. Since the damaged zone will affect the crack propagation rate due to cyclic loadings as well, the complete load history of a component therefore has to be considered. The crack propagation model presented in this paper is based on the damaged zone concept, and considers the history effect in the form of damaged zone build up during hold times, and subsequent destruction as the crack propagates onwards by rapidly applied load reversals. By incorporating crack closure for handling different R-values, an aero engine component spectrum is evaluated for a surface crack at 550 C. The result shows a good correlation to model simulation, despite the complexity of the load spectrum.

    Place, publisher, year, edition, pages
    Trans Tech Publications Inc., 2014
    Keywords
    Fatigue crack propagation, Inconel 718, Hold time effects, Crack growth modelling
    National Category
    Engineering and Technology
    Identifiers
    urn:nbn:se:liu:diva-104812 (URN)10.4028/www.scientific.net/AMR.891-892.759 (DOI)000337767700118 ()
    Available from: 2014-02-27 Created: 2014-02-27 Last updated: 2016-05-18Bibliographically approved
    5. Crack Length Evaluation for Cyclic and Sustained Loading at High Temperature Using Potential Drop
    Open this publication in new window or tab >>Crack Length Evaluation for Cyclic and Sustained Loading at High Temperature Using Potential Drop
    2015 (English)In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 55, no 3, p. 559-568Article in journal (Refereed) Published
    Abstract [en]

    Crack length evaluations for cyclic loading and sustained loading at high temperature and a mix of both have been conducted on Inconel 718 surface crack specimens at 550 C-a similar to. The choice of method for evaluating the crack length is seen to have a non-negligible impact on the resulting crack propagation rate values. In this paper, some aspects regarding how to evaluate such testing when using the potential drop technique are presented, with the aim of giving a firm explanation on how to proceed for the best possible result.

    Place, publisher, year, edition, pages
    Society for Experimental Mechanics (SEM), 2015
    Keywords
    Fatigue crack propagation; Fatigue test evaluation; Sustained load; Dwell time effects; Crack length evaluation; Potential drop
    National Category
    Mechanical Engineering
    Identifiers
    urn:nbn:se:liu:diva-117241 (URN)10.1007/s11340-014-9963-2 (DOI)000351444300007 ()
    Note

    Funding Agencies|Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through the Swedish research programme TURBO POWER

    Available from: 2015-04-22 Created: 2015-04-21 Last updated: 2017-12-04
    6. Three-dimensional crack growth modelling of a Ni-based superalloy at elevated temperature and sustained loading
    Open this publication in new window or tab >>Three-dimensional crack growth modelling of a Ni-based superalloy at elevated temperature and sustained loading
    2016 (English)In: Theoretical and applied fracture mechanics (Print), ISSN 0167-8442, E-ISSN 1872-7638Article in journal (Refereed) Published
    Abstract [en]

    High temperature materials subjected to elevated temperature have been shown to be sensitive to dwell times, giving an increased crack growth rate. The interaction between these dwell times and rapid cyclic loads have been shown to constitute a complex problem. Many models have been developed for 1D conditions, but the application to general 3D conditions has seldom been seen, although this is the most common case in most structures. In this paper a model for taking care of the interaction between these load modes in general 3D crack growth has been developed. The model uses 1D results for extension to general 3D, thus providing for local crack front evolution with a minimum of numerical simulations. The model has been implemented for usage with finite element calculations and several different tests are simulated and compared with experimental results for the nickel based superalloy Inconel 718 at 550◦C. The simulation results show crack shapes in agreement with experimental fracture surfaces and time to failure.

    Keywords
    Sustained load, Crack growth modelling, Crack tunnelling, Ni-based superalloy, High temperature
    National Category
    Applied Mechanics Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-121004 (URN)10.1016/j.tafmec.2015.11.008 (DOI)000369204600002 ()
    Note

    Funding agencies:  Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through the Swedish research programme TURBO POWER

    Vid tiden för disputation förelåg publikationen som manuskript

    Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
    7. Modeling of Crack Growth With Dwell Time for Aero-engine Spectra Loadings in a Ni-Based Superalloy
    Open this publication in new window or tab >>Modeling of Crack Growth With Dwell Time for Aero-engine Spectra Loadings in a Ni-Based Superalloy
    Show others...
    2016 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, p. 012501-012501Article in journal (Refereed) Published
    Abstract [en]

    Testing and simulation of aero-engine spectra with dwell times are reported in this paper. The modeling concept used is built on linear elastic fracture mechanics (LEFM) and provides a history-dependent evolution description of dwell damage and its interaction with cyclic load. The simulations have been carried out for three spectra: (1) cyclic loads, (2) combined sustained load and cyclic loads, and (3) slow load ramps and cyclic loads, all for surface cracks at 550 °C for Inconel 718. All simulations show reasonable good agreement with experimental results. Prediction of multiple tests of several batches is also provided to show statistical scatter.

    Place, publisher, year, edition, pages
    ASME Press, 2016
    National Category
    Applied Mechanics Mechanical Engineering Materials Engineering
    Identifiers
    urn:nbn:se:liu:diva-121005 (URN)10.1115/1.4031155 (DOI)000371127900012 ()
    Note

    Funding agencies: Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through Swedish Research Programme TURBO POWER

    Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
    8. Scatter in Dwell Time Cracking for a Ni-Based Superalloy in Combination With Overloads
    Open this publication in new window or tab >>Scatter in Dwell Time Cracking for a Ni-Based Superalloy in Combination With Overloads
    Show others...
    2016 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, p. 012502-012502Article in journal (Refereed) Published
    Abstract [en]

    In this paper, scatter in crack growth for dwell time loadings in combination with overloads has been investigated. Multiple tests were performed for surface cracks at 550 °C in the commonly used high temperature material Inconel 718. The test specimens originate from two different batches which also provide for a discussion of how material properties affect the dwell time damage and overload impact. In combination with these tests, an investigation of the microstructure was also carried out, which shows how it influences the growth rate. The results from this study show that, in order to take overloads into consideration when analyzing spectrum loadings containing dwell times, one needs a substantial amount of material data available as the scatter seen from one batch to the other are of significant proportions.

    Place, publisher, year, edition, pages
    ASME Press, 2016
    National Category
    Mechanical Engineering Materials Engineering Applied Mechanics
    Identifiers
    urn:nbn:se:liu:diva-121007 (URN)10.1115/1.4031157 (DOI)000371127900013 ()
    Note

    Funding agencies: Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through Swedish research programme TURBO POWER

    Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
    9. Thermomechanical Fatigue Crack Growth Modeling in a Ni-Based Superalloy Subjected to Sustained Load
    Open this publication in new window or tab >>Thermomechanical Fatigue Crack Growth Modeling in a Ni-Based Superalloy Subjected to Sustained Load
    2016 (English)In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, p. 012503-012503Article in journal (Refereed) Published
    Abstract [en]

    Thermomechanical fatigue (TMF) crack growth modeling has been conducted on Inconel 718 with dwell time at maximum load. A history dependent damage model taking dwell damage into account, developed under isothermal conditions, has been extended for TMF conditions. Parameter determination for the model is carried out on isothermal load controlled tests at 550–650 °C for surface cracks, which later have been used to extrapolate parameters used for TMF crack growth. Further, validation of the developed model is conducted on a notched specimen subjected to strain control at 50–550 °C. Satisfying results are gained within reasonable scatter level compared for test and simulated number of cycles to failure.

    Place, publisher, year, edition, pages
    ASME Press, 2016
    National Category
    Mechanical Engineering Materials Engineering Applied Mechanics
    Identifiers
    urn:nbn:se:liu:diva-121008 (URN)10.1115/1.4031158 (DOI)000371127900014 ()
    Note

    Funding agencies: Swedish Energy Agency; Siemens Industrial Turbomachinery AB; GKN Aerospace Engine Systems; Royal Institute of Technology through Swedish research programme TURBO POWER

    Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2017-12-04Bibliographically approved
    10. Impact of high cycle fatigue on dwell time crack growth in a Ni-based superalloy
    Open this publication in new window or tab >>Impact of high cycle fatigue on dwell time crack growth in a Ni-based superalloy
    Show others...
    2015 (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Sustained load have been shown to give rise to increased crack growth rate at elevated temperature. Such loads generate a history dependent fatigue problem due to weakening and cracking of grain boundaries during dwell times, later broken apart during subsequent load cycles. So far most studies have focused on sustained load and the interaction of load cycles, overloads, and temperature, but few studies have been carried out for vibrations and how these affect the dwell time crack growth. Vibrations of different kinds are frequently seen in engine components, and present in combination with sustained loads a more realistic loading situation than the latter itself. An investigation of how a vibrational load affects the dwell time cracking and how to incorporate it in a modelling context is therefore of importance. In this paper a study of the most frequently used gas turbine material, Inconel 718, has been carried out. Mechanical testing has been conducted at 550◦C for surface cracks with and without the interaction of engine vibrations on sustained load, here represented by a superimposed high cycle fatigue (HCF) load. Subsequent investigation of the fracture behaviour was performed by Scanning Electron Microscope (SEM) and the modelling work has been conducted by incorporating the HCF load description within a history dependent crack growth law. The obtained results show reasonable accuracy with respect to the mechanical tests.

    Keywords
    Hold time effects, Dwell times, Sustained load, Crack growth modelling, Inconel 718, High temperature
    National Category
    Mechanical Engineering Materials Engineering Applied Mechanics
    Identifiers
    urn:nbn:se:liu:diva-121009 (URN)
    Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2015-09-02Bibliographically approved
  • 8.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Saarimäki, Jonas
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Gustafsson, David
    Siemens Ind Turbomachinery, Sweden.
    Mansson, Tomas
    GKN Aerosp Engine Syst, Sweden.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    SCATTER IN DWELL TIME CRACKING FOR A NI-BASED SUPERALLOY IN COMBINATION WITH OVERLOADS2015In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2015, VOL 7A, ASME Press, 2015, no V07AT28A004Conference paper (Refereed)
    Abstract [en]

    In this paper scatter in crack growth for dwell time loadings combination with overloads has been investigated. Multiple Jsts were performed for surface cracks at 5500C in the commonly sed high temperature material Inconel 718. The test specimens -iginate from two different batches which also provides for a disission of how material properties affect the dwell time damage rnd overload impact. In combination with these tests an investiation of the microstructure was also carried out, which shows 9w it influences the growth rate. The results from this study show tat, in order to take overloads into consideration when analysing,ectrum loadings containing dwell times, one needs a substantial mount of material data available as the scatter seen from one atch to the other is of significant proportions.

  • 9.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Saarimäki, Jonas
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Gustafsson, David
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Månsson, Tomas
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Scatter in Dwell Time Cracking for a Ni-Based Superalloy in Combination With Overloads2016In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, p. 012502-012502Article in journal (Refereed)
    Abstract [en]

    In this paper, scatter in crack growth for dwell time loadings in combination with overloads has been investigated. Multiple tests were performed for surface cracks at 550 °C in the commonly used high temperature material Inconel 718. The test specimens originate from two different batches which also provide for a discussion of how material properties affect the dwell time damage and overload impact. In combination with these tests, an investigation of the microstructure was also carried out, which shows how it influences the growth rate. The results from this study show that, in order to take overloads into consideration when analyzing spectrum loadings containing dwell times, one needs a substantial amount of material data available as the scatter seen from one batch to the other are of significant proportions.

  • 10.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Saarimäki, Jonas
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Månsson, Tomas
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Impact of high cycle fatigue on dwell time crack growth in a Ni-based superalloy2015Manuscript (preprint) (Other academic)
    Abstract [en]

    Sustained load have been shown to give rise to increased crack growth rate at elevated temperature. Such loads generate a history dependent fatigue problem due to weakening and cracking of grain boundaries during dwell times, later broken apart during subsequent load cycles. So far most studies have focused on sustained load and the interaction of load cycles, overloads, and temperature, but few studies have been carried out for vibrations and how these affect the dwell time crack growth. Vibrations of different kinds are frequently seen in engine components, and present in combination with sustained loads a more realistic loading situation than the latter itself. An investigation of how a vibrational load affects the dwell time cracking and how to incorporate it in a modelling context is therefore of importance. In this paper a study of the most frequently used gas turbine material, Inconel 718, has been carried out. Mechanical testing has been conducted at 550◦C for surface cracks with and without the interaction of engine vibrations on sustained load, here represented by a superimposed high cycle fatigue (HCF) load. Subsequent investigation of the fracture behaviour was performed by Scanning Electron Microscope (SEM) and the modelling work has been conducted by incorporating the HCF load description within a history dependent crack growth law. The obtained results show reasonable accuracy with respect to the mechanical tests.

  • 11.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Saarimäki, Jonas
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Månsson, Tomas
    GDN Aerospace Engine Systems, Trollhättan.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Influence of Superimposed Vibrational Load on Dwell Time Crack Growth in a Ni-Based Superalloy2016In: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 87, p. 301-310Article in journal (Refereed)
    Abstract [en]

    Sustained loads have for some Ni-based superalloys been shown to give rise to increased crack growth rate at elevated temperature. Such loads generate a history dependent fatigue problem due to weakening and cracking of grain boundaries during dwell times, later broken apart during subsequent load cycles. So far most studies have focused on the interaction of load cycles, overloads, and temperature. However, vibrations of different kinds are to some extent always present in engine components, and an investigation of how such loads affect the dwell time cracking, and how to incorporate them in a modelling context, is therefore of importance. In this paper a study of the most frequently used gas turbine material, Inconel 718, has been carried out. Mechanical crack propagation testing has been conducted at 550 °C for surface cracks with and without the interaction of superimposed vibrational loads. Subsequent investigation of the fracture behaviour was performed by scanning electron microscopy and the modelling work has been conducted by incorporating the vibration load description within a history dependent crack growth law. The obtained results show reasonable accuracy with respect to the mechanical test results.

  • 12.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, The Institute of Technology.
    Crack Length Evaluation for Cyclic and Sustained Loading at High Temperature Using Potential Drop2015In: Experimental mechanics, ISSN 0014-4851, E-ISSN 1741-2765, Vol. 55, no 3, p. 559-568Article in journal (Refereed)
    Abstract [en]

    Crack length evaluations for cyclic loading and sustained loading at high temperature and a mix of both have been conducted on Inconel 718 surface crack specimens at 550 C-a similar to. The choice of method for evaluating the crack length is seen to have a non-negligible impact on the resulting crack propagation rate values. In this paper, some aspects regarding how to evaluate such testing when using the potential drop technique are presented, with the aim of giving a firm explanation on how to proceed for the best possible result.

  • 13.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Three-dimensional crack growth modelling of a Ni-based superalloy at elevated temperature and sustained loading2016In: Theoretical and applied fracture mechanics (Print), ISSN 0167-8442, E-ISSN 1872-7638Article in journal (Refereed)
    Abstract [en]

    High temperature materials subjected to elevated temperature have been shown to be sensitive to dwell times, giving an increased crack growth rate. The interaction between these dwell times and rapid cyclic loads have been shown to constitute a complex problem. Many models have been developed for 1D conditions, but the application to general 3D conditions has seldom been seen, although this is the most common case in most structures. In this paper a model for taking care of the interaction between these load modes in general 3D crack growth has been developed. The model uses 1D results for extension to general 3D, thus providing for local crack front evolution with a minimum of numerical simulations. The model has been implemented for usage with finite element calculations and several different tests are simulated and compared with experimental results for the nickel based superalloy Inconel 718 at 550◦C. The simulation results show crack shapes in agreement with experimental fracture surfaces and time to failure.

  • 14.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Gustafsson, David
    Siemens Ind Turbomachinery AB, Sweden.
    Mansson, Tomas
    GKN Aerosp Engine Syst, Sweden.
    MODELLING OF CRACK GROWTH WITH DWELL TIME FOR AERO ENGINE SPECTRA LOADINGS IN A NI-BASED SUPERALLOY2015In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2015, VOL 7A, ASME Press, 2015, no V07AT28A003Conference paper (Refereed)
    Abstract [en]

    Testing and simulation of aero engine spectra with dwell Imes are reported in this paper. The modelling concept used built on LEFM and provides a history dependent evolution 2scription of dwell damage and its interaction with cyclic load. he simulations have been carried out for three spectra, 1) cyclic ?ads, 2) combined sustained load and cyclic loads and 3) slow ad ramps and cyclic loads, all for surface cracks at 550 C for nconel 718. All simulations show reasonable good agreement ith experimental results. Prediction of multiple tests of several atches is also provided to show statistical scatter

  • 15.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Gustafsson, David
    Siemens Industrial Turbomachinery AB, Finspång, Sweden.
    Månsson, Tomas
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Modeling of Crack Growth With Dwell Time for Aero-engine Spectra Loadings in a Ni-Based Superalloy2016In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, p. 012501-012501Article in journal (Refereed)
    Abstract [en]

    Testing and simulation of aero-engine spectra with dwell times are reported in this paper. The modeling concept used is built on linear elastic fracture mechanics (LEFM) and provides a history-dependent evolution description of dwell damage and its interaction with cyclic load. The simulations have been carried out for three spectra: (1) cyclic loads, (2) combined sustained load and cyclic loads, and (3) slow load ramps and cyclic loads, all for surface cracks at 550 °C for Inconel 718. All simulations show reasonable good agreement with experimental results. Prediction of multiple tests of several batches is also provided to show statistical scatter.

  • 16.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    Thermomechanical Fatigue Crack Growth Modeling in a Ni-Based Superalloy Subjected to Sustained Load2016In: Journal of engineering for gas turbines and power, ISSN 0742-4795, E-ISSN 1528-8919, Vol. 138, no 1, p. 012503-012503Article in journal (Refereed)
    Abstract [en]

    Thermomechanical fatigue (TMF) crack growth modeling has been conducted on Inconel 718 with dwell time at maximum load. A history dependent damage model taking dwell damage into account, developed under isothermal conditions, has been extended for TMF conditions. Parameter determination for the model is carried out on isothermal load controlled tests at 550–650 °C for surface cracks, which later have been used to extrapolate parameters used for TMF crack growth. Further, validation of the developed model is conducted on a notched specimen subjected to strain control at 50–550 °C. Satisfying results are gained within reasonable scatter level compared for test and simulated number of cycles to failure.

  • 17.
    Storgärds, Erik
    et al.
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Simonsson, Kjell
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Sjöström, Sören
    Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
    Moverare, Johan
    Linköping University, Department of Management and Engineering, Engineering Materials. Linköping University, Faculty of Science & Engineering.
    THERMO-MECHANICAL FATIGUE CRACK GROWTH MODELLING IN A NI-BASED SUPERALLOY SUBJECTED TO SUSTAINED LOAD2015In: PROCEEDINGS OF THE ASME TURBO EXPO: TURBINE TECHNICAL CONFERENCE AND EXPOSITION, 2015, VOL 7A, ASME Press, 2015, no V07AT28A006Conference paper (Refereed)
    Abstract [en]

    Thermo-mechanical fatigue (TMF) crack growth modelling as been conducted on Inconel 718 with dwell time at maximum;ad. A history dependent damage model taking dwell damage uto account, developed under isothermal conditions, has been xtended for TMF conditions. Parameter determination for the lodel is carried out on isothermal load controlled tests at 55050 C for surface cracks, which later have been used to extrapole parameters used for TMF crack growth. Further, validation the developed model is conducted on a notched specimen sub?cted to strain control at 50-550 C. Satisfying results are gained ithin reasonable scatter level compared for test and simulated umber of cycles to failure.

1 - 17 of 17
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