STP868

    Characterization of Crack Closure

    Published: Jan 1985


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    Abstract

    Crack opening and closure levels are determined for small cracks growing from sharp and blunt notches during cyclic loading. Crack tip opening displacement measurements as low as 0.1 μm are reported. Experimental crack opening levels are compared with analytical crack opening levels for various stress intensity ranges, crack lengths, and R-ratios.

    The crack growth rate behavior in the vicinity of blunt and sharp notches as well as in smooth specimens is studied. The high crack growth rates observed for small cracks growing from blunt notches are interpreted based on the variation of crack opening level with the crack length. Effective stress intensity range is defined to account for crack closure effects. The crack growth rate correlated well with the effective stress intensity range obtained from sharply and bluntly notched specimens of 1070 steel.

    Keywords:

    fatigue, fracture mechanics, crack closure, small cracks, crack tip opening displacement, stresses, notch, specimens


    Author Information:

    Sehitoglu, H
    Assistant Professor, University of Illinois, Urbana, IL


    Paper ID: STP34263S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP34263S


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