STP791

    Approximate Influence Functions for Part-Circumferential Interior Surface Cracks in Pipes

    Published: Jan 1983


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    Abstract

    Approximate influence functions are presented for a part-circumferential semielliptical interior surface crack in a circular pipe. The influence functions are derived from the crack surface opening displacements obtained by the use of boundary integral equation techniques. Such functions are useful in evaluating stress-intensity factors for cracks in bodies subjected to complex stress conditions, and convenient curve fits suitable for numerical calculations are provided. The stress intensities are obtainable for arbitrary stresses by numerical integration techniques. Comparisons with existing solutions indicate that the influence functions provide results of suitable accuracy for engineering purposes. The results indicate that the stress-intensity factor is not strongly dependent on the parameter Ri/h or on whether the crack is longitudinal or circumferential. Details of the variation of K along the crack front are not obtainable from the influence functions, only “root-mean-square (RMS)-averaged” values are generated. However, such values are useful in the analysis of the growth of semielliptical cracks, and the results presented should be of wide use in the analysis of such cracks under complex stress conditions.

    Keywords:

    cracks, stress-intensity factors, influence functions, pipes, fracture mechanics


    Author Information:

    Lim, EY
    Division managers, Science Applications, Inc., Palo Alto, Calif.

    Dedhia, DD
    Materials scientist, Science Applications, Inc., Sunnyvale, Calif.

    Harris, DO
    Division managers, Science Applications, Inc., Palo Alto, Calif.


    Paper ID: STP37077S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP37077S


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