The effect of loss of constraint on the initation of ductile fracture in a MINI-CT

    Research outputpeer-review


    As one of the most appealing miniaturized geometries for fracture toughness characterization, the miniature compact tension (mini-CT) geometry was demonstrated to provide reliable fracture toughness measurement in the ductile-to-brittle transition regime and Master Curve assessment. However, when using a mini-CT in the upper shelf (fully ductile) regime, the ductile crack initiation and the crack growth resistance tend to be underestimated for most of the investigated RPV steels. Previous experimental investigations have attributed the underestimation of the crack resistance properties to two concurrent processes related to loss of constraint and cold working occurring in the ligament ahead of crack tip during cracking, and gave an engineering size correction that mainly accounts for the thickness of the specimens. In this study, finite element simulations and two micromechanics-based approaches: the Rice-Tracey void growth model and Thomason void coalescence model are combined, aimed at investigating the role that the loss of constraint plays in the initiation of ductile fracture in a mini-CT and providing numerical evidence to support the proposal of the size correction on the critical fracture toughness. The final objective of this paper is to estimate the ductile crack initiation behavior that would be obtained from a standard 1T-CT specimen by applying appropriate size correction on a mini-CT. The results show that the method incorporating the finite element simulations and two micromechanics-based approaches can well describe the effects of loss of constraint for different materials, thus contributing to the size correction of critical fracture toughness of mini-CT in various conditions.
    Original languageEnglish
    Title of host publicationProceedings of the ASME 2023 Pressure Vessels & Piping Conference
    Subtitle of host publicationJuly 16-21, 2023, Atlanta, Georgia
    PublisherASME - The American Society of Mechanical Engineers
    Number of pages10
    StatePublished - 16 Jul 2023
    Event2023 - PVP: Pressure Vessels & Piping Conference - The Westin Peachtree Plaza, Atlanta
    Duration: 16 Jul 202321 Jul 2023


    Conference2023 - PVP
    Country/TerritoryUnited States
    Internet address

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