Towards Crack Arrest Testing Using Miniature Specimens

    Volume 5, Issue 9 (October 2008)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 7 October 2008

    Page Count: 15


    Scibetta, M.
    SCK-CEN, Mol,

    Link, R.
    US Naval Academy, Annapolis,

    Schuurmans, J.
    SCK-CEN, Mol,

    Lucon, E.
    SCK-CEN, Mol,

    (Received 24 January 2007; accepted 4 September 2008)

    Abstract

    Crack arrest is an important concept that can be useful to guarantee the safety of reactor pressure vessels. In case of a pressurized thermal shock, a postulated crack can initiate and arrest due to a decrease in driving force combined with an increase in material toughness due to the thermal and neutron embrittlement gradient along the thickness. Due to the size of the specimen and the difficulty in obtaining valid results according to the ASTM E1221-06 standard, “Standard Test Method for Determining Plane-Strain Crack-Arrest Fracture Toughness, KIa, of Ferritic Steels,” current efforts to develop this technique for irradiated materials are very limited. However, advances in dynamic fracture modeling and elastic-plastic fracture mechanics open the possibility of using miniature crack arrest specimens. We have developed a stiff setup to perform crack arrest tests on precracked Charpy (PCCv) specimens. Different strategies were evaluated to provide enough reduction in driving force to produce arrest. Special attention is given to the starter notch and different starter notch preparations are investigated: precracking, chevron, and brittle weld. Testing configurations were found that guarantee crack arrest with sufficient remaining ligament. The dynamic loading condition is investigated experimentally using strain gauges. Finite element calculations of an arresting crack are also performed in order to provide more insight of the loading after the crack arrest event. Although it is not yet possible to derive the arrest fracture toughness from the PCCv testing, results are encouraging and open new perspectives in the field of crack arrest determination.


    Paper ID: JAI101002

    DOI: 10.1520/JAI101002

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    Author
    Title Towards Crack Arrest Testing Using Miniature Specimens
    Symposium Fifth Symposium on Small Specimen Test Techniques, 2007-02-01
    Committee E10