New Equation for the Plastic Correction Factor η for J-Integral Determination from Test Results of Three-Point-Bend Specimens

    (Received 29 September 2013; accepted 18 December 2013)

    Published Online: 2014

    CODEN: MPCOAD

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    Abstract

    When material yielding occurs, the stress intensity factor, K, no longer correctly characterizes the magnitude of the stress field around the crack tip. For significant amounts of yielding, the J-integral approach is applied as an advanced tool. In practice, for many engineering applications, the non-linear plasticity effects are of importance and therefore material behavior beyond yield needs an accurate description for input to tools for assessment. This work presents J-integral values of two different steel grades (1006 and 4340) using a newly developed analytical approach for the correction factors ηpl, which takes into account the elastic–plastic properties of the material. The evaluation approach is based on absorbed energies in a Charpy-sized specimen during the elastic and plastic deformation phases. Values of these energy terms were obtained via numerical simulation of 1006 and 4340 steel Charpy-sized specimens loaded in three-point-bending. This work highlights the effect of materials plastic properties on the J-integral. Different steel grades show different amounts of plasticity defined by the strain-hardening exponent and the strain-hardening constant and these influence the fracture parameters. Application of the plastic correction factor ηpl to Charpy-sized specimens, considering the respective plastic properties of the materials, leads to values of ηpl equal to 2.286 for 1006 steel and 2.621 for 4340 steel.


    Author Information:

    Gintalas, Marius
    The Univ. of Manchester, Manchester,

    Ziliukas, Antanas
    Klaipeda Univ., Klaipeda, Bijunu 17

    Ainsworth, Robert A.
    The Univ. of Manchester, Manchester,


    Stock #: MPC20130053

    ISSN: 2165-3992

    DOI: 10.1520/MPC20130053

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    Author
    Title New Equation for the Plastic Correction Factor η for J-Integral Determination from Test Results of Three-Point-Bend Specimens
    Symposium , 0000-00-00
    Committee E08