STP1380: Use of Instrumented Charpy Test for Determination of Crack Initiation Toughness

    Viehrig, H-W
    Senior Scientist, Institute for Safety Research, Forschungszentrum Rossendorf e.V., Dresden,

    Boehmert, J
    Head of Department, Institute for Safety Research, Forschungszentrum Rossendorf e.V., Dresden,

    Richter, H
    Research Scientist, Institute for Safety Research, Forschungszentrum Rossendorf e.V., Dresden,

    Valo, M
    Group Manager, VTT Manufacturing Technology, VTT

    Pages: 12    Published: Jan 2000


    Abstract

    The instrumented Charpy test provides the opportunity to determine dynamic crack initiation (Jid) toughness. Under the condition of the impact bending test, the critical step for evaluating Jid is the identification of the ductile crack initiation point on the impact load versus displacement curve. Therefore, acoustic emission (AE) was monitored and used as a tool for ductile crack initiation detection. With a tup-integrated AE sensor, different types of AE events could be identified during loading of a Charpy size specimen. One type of AE signal appeared in the temporal vicinity of crack initiation and was applied to define Jid. A verification of these results was performed by simultaneous optical measurement of COD with an inverted impact pendulum. Additionally “Cleavage R-Curves” (JdΔa) were evaluated and physical crack initiation toughness (Jidszw) values were determined by measurement of the stretch zone width (SZW).

    Keywords:

    dynamic fracture toughness, ductile crack initiation, single specimen method, J-integral, acoustic emission, instrumented impact testing


    Paper ID: STP14406S

    Committee/Subcommittee: E28.07

    DOI: 10.1520/STP14406S


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