STP627: A Crack Arrest Measuring Procedure for KIm, KID, and KIa Properties

    Hoagland, RG
    Principal researchers, senior researcher, and manager, Battelle Columbus Laboratories, Columbus, Ohio

    Rosenfield, AR
    Principal researchers, senior researcher, and manager, Battelle Columbus Laboratories, Columbus, Ohio

    Gehlen, PC
    Principal researchers, senior researcher, and manager, Battelle Columbus Laboratories, Columbus, Ohio

    Hahn, GT
    Principal researchers, senior researcher, and manager, Battelle Columbus Laboratories, Columbus, Ohio

    Pages: 26    Published: Jan 1977


    Abstract

    New developments are described which offer a flexible procedure for measuring the fracture resistance values, KIm, KID, and KIa which characterize the crack arrest behavior of materials. The procedure relies on a dynamically stiff, wedge-loading which limits dynamic energy exchanges between the test specimen and the testing machine. This makes it possible to interpret both small and large crack jumps without recourse to crack velocity measurements. The procedure is general and can be applied to ordinary and duplex rectangular and contoured double-cantilever-beam (DCB) specimens, and to compact and single-edge-notched (SEN) specimens when dynamic analyses for these shapes become available. The paper examines the virtues of the different specimen configurations, size and thickness requirements, possible upper and lower bounds on the size of the crack jump, and the problem of branching and side grooves. Measurements of specimen machine interactions are described. Results obtained for A533B steel with a series of rectangular DCB specimens illustrate the dependence of KIa on the size of the crack jump as well as the previously proposed relations between KIa and KIm or KID. The results confirm that the KIm (or KID) values obtained with the new procedure from static measurements of load point displacement and the crack length at arrest agree with values derived from crack velocity measurements. The experiments also illustrate that duplex DCB specimens with modest dimensions (400 by 140 by 50 mm) have the capacity for measuring KIm and KID values in excess of 150 MPa·m½.

    Keywords:

    crack propagation crack arrest, fractures (materials), fracture properties, fracture strength, fast fracture, crack velocity, cantilever beams, steels


    Paper ID: STP27388S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP27388S


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