STP668

    Studies on Crack Initiation and Stable Crack Growth

    Published: Jan 1979


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    Abstract

    Experimental results are presented which suggest that parameters based on the J-integral and the crack opening tip displacement δ are viable characterizations of crack initiation and stable crack growth. Observations based on some theoretical studies and finite-element investigations of the extending crack revealed that J and δ when appropriately employed do indeed characterize the near-field deformation. In particular, the analytical and experimental studies show that crack initiation is characterizable by the critical value of J or δ, and stable crack growth is characterizable in terms of the J or δ resistance curves. The crack opening angle, dδ/da, appears to be relatively constant over a significant range of crack growth. Thus, appropriate measures of the material toughness associated with initiation are JIc and δIc, and measures of material toughness associated with stable crack growth are given by the dimensionless parameters TJ [= (Eo2)(dJ/da)] and Tδ [= (Eo)(dδ/(da)]. The two-parameter characterization of fracture behavior by JIc and TJ or δIc and Tδ is analogous to the characterization of deformation behavior by the yield stress and strain hardening exponent.

    Keywords:

    fracture, cracks, crack initiation, crack growth, crack opening displacement, crack opening angle, J-integral, resistance curve, plastic deformation, elastic properties, plastic properties, fracture toughness, tearing modulus, crack propagation


    Author Information:

    Shih, CF
    Mechanical engineers, Corporate Research and Development, and metallurgical engineer, Materials and Processes Laboratory, General Electric Co., Schenectady, N.Y.

    deLorenzi, HG
    Mechanical engineers, Corporate Research and Development, and metallurgical engineer, Materials and Processes Laboratory, General Electric Co., Schenectady, N.Y.

    Andrews, WR
    Mechanical engineers, Corporate Research and Development, and metallurgical engineer, Materials and Processes Laboratory, General Electric Co., Schenectady, N.Y.


    Paper ID: STP35827S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP35827S


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