Predicting creep rupture from early strain data

Stefan Holmström, Pertti Auerkari

    Research output: Contribution to journalArticleScientificpeer-review

    5 Citations (Scopus)

    Abstract

    To extend creep life modelling from classical rupture modelling, a robust and effective parametric strain model has been developed. The model can reproduce with good accuracy all parts of the creep curve, economically utilising the available rupture models. The resulting combined model can also be used to predict rupture from the available strain data, and to further improve the rupture models. The methodology can utilise unfailed specimen data for life assessment at lower stress levels than what is possible from rupture data alone. Master curves for creep strain and rupture have been produced for oxygen-free phosphorus-doped (OFP) copper with a maximum testing time of 51,000 h. Values of time to specific strain at given stress (40–165 MPa) and temperature (125–350 °C) were fitted to the models in the strain range of 0.1–38%. With typical inhomogeneous multi-batch creep data, the combined strain and rupture modelling involves the steps of investigation of the data quality, extraction of elastic and creep strain response, rupture modelling, data set balancing and creep strain modelling. Finally, the master curves for strain and rupture are tested and validated for overall fitting efficiency. With the Wilshire equation as the basis for the rupture model, the strain model applies classical parametric principles with an Arrhenius type of thermal activation and a power law type of stress dependence for the strain rate. The strain model also assumes that the processes of primary and secondary creep can be reasonably correlated. The rupture model represents a clear improvement over previous models in the range of the test data. The creep strain information from interrupted and running tests were assessed together with the rupture data investigating the possibility of rupture model improvement towards lower stress levels by inverse utilisation of the combined rupture based strain model. The developed creep strain model together with the improved rupture model is foreseen to give a sound basis for life predictions of the OFP copper overpack canister for the spent nuclear fuel.
    Original languageEnglish
    Pages (from-to)25-28
    Number of pages4
    JournalMaterials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
    Volume510-511
    DOIs
    Publication statusPublished - 2009
    MoE publication typeA1 Journal article-refereed
    Event11th International Conference of Creep and Fracture of Engineering Materials and Structures, CREEP 2008 - Bad Berneck, Germany
    Duration: 4 May 20089 May 2008

    Fingerprint

    Creep
    Phosphorus
    phosphorus
    Copper
    curves
    cans
    testing time
    Oxygen
    copper
    spent fuels
    nuclear fuels
    Spent fuels
    Nuclear fuels
    oxygen
    strain rate
    Data structures
    Strain rate
    Chemical activation
    Acoustic waves
    activation

    Keywords

    • Creep
    • Life prediction
    • OFP copper
    • Strain modeling

    Cite this

    @article{ab28939308be4226a394992f6685e021,
    title = "Predicting creep rupture from early strain data",
    abstract = "To extend creep life modelling from classical rupture modelling, a robust and effective parametric strain model has been developed. The model can reproduce with good accuracy all parts of the creep curve, economically utilising the available rupture models. The resulting combined model can also be used to predict rupture from the available strain data, and to further improve the rupture models. The methodology can utilise unfailed specimen data for life assessment at lower stress levels than what is possible from rupture data alone. Master curves for creep strain and rupture have been produced for oxygen-free phosphorus-doped (OFP) copper with a maximum testing time of 51,000 h. Values of time to specific strain at given stress (40–165 MPa) and temperature (125–350 °C) were fitted to the models in the strain range of 0.1–38{\%}. With typical inhomogeneous multi-batch creep data, the combined strain and rupture modelling involves the steps of investigation of the data quality, extraction of elastic and creep strain response, rupture modelling, data set balancing and creep strain modelling. Finally, the master curves for strain and rupture are tested and validated for overall fitting efficiency. With the Wilshire equation as the basis for the rupture model, the strain model applies classical parametric principles with an Arrhenius type of thermal activation and a power law type of stress dependence for the strain rate. The strain model also assumes that the processes of primary and secondary creep can be reasonably correlated. The rupture model represents a clear improvement over previous models in the range of the test data. The creep strain information from interrupted and running tests were assessed together with the rupture data investigating the possibility of rupture model improvement towards lower stress levels by inverse utilisation of the combined rupture based strain model. The developed creep strain model together with the improved rupture model is foreseen to give a sound basis for life predictions of the OFP copper overpack canister for the spent nuclear fuel.",
    keywords = "Creep, Life prediction, OFP copper, Strain modeling",
    author = "Stefan Holmstr{\"o}m and Pertti Auerkari",
    note = "Project code: 24087 Project code: 6900",
    year = "2009",
    doi = "10.1016/j.msea.2008.04.106",
    language = "English",
    volume = "510-511",
    pages = "25--28",
    journal = "Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing",
    issn = "0921-5093",
    publisher = "Elsevier",

    }

    Predicting creep rupture from early strain data. / Holmström, Stefan; Auerkari, Pertti.

    In: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing, Vol. 510-511, 2009, p. 25-28.

    Research output: Contribution to journalArticleScientificpeer-review

    TY - JOUR

    T1 - Predicting creep rupture from early strain data

    AU - Holmström, Stefan

    AU - Auerkari, Pertti

    N1 - Project code: 24087 Project code: 6900

    PY - 2009

    Y1 - 2009

    N2 - To extend creep life modelling from classical rupture modelling, a robust and effective parametric strain model has been developed. The model can reproduce with good accuracy all parts of the creep curve, economically utilising the available rupture models. The resulting combined model can also be used to predict rupture from the available strain data, and to further improve the rupture models. The methodology can utilise unfailed specimen data for life assessment at lower stress levels than what is possible from rupture data alone. Master curves for creep strain and rupture have been produced for oxygen-free phosphorus-doped (OFP) copper with a maximum testing time of 51,000 h. Values of time to specific strain at given stress (40–165 MPa) and temperature (125–350 °C) were fitted to the models in the strain range of 0.1–38%. With typical inhomogeneous multi-batch creep data, the combined strain and rupture modelling involves the steps of investigation of the data quality, extraction of elastic and creep strain response, rupture modelling, data set balancing and creep strain modelling. Finally, the master curves for strain and rupture are tested and validated for overall fitting efficiency. With the Wilshire equation as the basis for the rupture model, the strain model applies classical parametric principles with an Arrhenius type of thermal activation and a power law type of stress dependence for the strain rate. The strain model also assumes that the processes of primary and secondary creep can be reasonably correlated. The rupture model represents a clear improvement over previous models in the range of the test data. The creep strain information from interrupted and running tests were assessed together with the rupture data investigating the possibility of rupture model improvement towards lower stress levels by inverse utilisation of the combined rupture based strain model. The developed creep strain model together with the improved rupture model is foreseen to give a sound basis for life predictions of the OFP copper overpack canister for the spent nuclear fuel.

    AB - To extend creep life modelling from classical rupture modelling, a robust and effective parametric strain model has been developed. The model can reproduce with good accuracy all parts of the creep curve, economically utilising the available rupture models. The resulting combined model can also be used to predict rupture from the available strain data, and to further improve the rupture models. The methodology can utilise unfailed specimen data for life assessment at lower stress levels than what is possible from rupture data alone. Master curves for creep strain and rupture have been produced for oxygen-free phosphorus-doped (OFP) copper with a maximum testing time of 51,000 h. Values of time to specific strain at given stress (40–165 MPa) and temperature (125–350 °C) were fitted to the models in the strain range of 0.1–38%. With typical inhomogeneous multi-batch creep data, the combined strain and rupture modelling involves the steps of investigation of the data quality, extraction of elastic and creep strain response, rupture modelling, data set balancing and creep strain modelling. Finally, the master curves for strain and rupture are tested and validated for overall fitting efficiency. With the Wilshire equation as the basis for the rupture model, the strain model applies classical parametric principles with an Arrhenius type of thermal activation and a power law type of stress dependence for the strain rate. The strain model also assumes that the processes of primary and secondary creep can be reasonably correlated. The rupture model represents a clear improvement over previous models in the range of the test data. The creep strain information from interrupted and running tests were assessed together with the rupture data investigating the possibility of rupture model improvement towards lower stress levels by inverse utilisation of the combined rupture based strain model. The developed creep strain model together with the improved rupture model is foreseen to give a sound basis for life predictions of the OFP copper overpack canister for the spent nuclear fuel.

    KW - Creep

    KW - Life prediction

    KW - OFP copper

    KW - Strain modeling

    U2 - 10.1016/j.msea.2008.04.106

    DO - 10.1016/j.msea.2008.04.106

    M3 - Article

    VL - 510-511

    SP - 25

    EP - 28

    JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

    JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing

    SN - 0921-5093

    ER -