STP590

    Running Ductile Fracture in a Pressurized Line Pipe

    Published: Jan 1976


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    Abstract

    A model is developed for steady state propagation of a ductile crack in an initially pressurized line pipe. The analysis is directed toward the high toughness range of material behavior, for which extensive yielding occurs in the pipeline walls, and the material is represented as rigid-ideal plastic. Further, to obtain a tractable model, kinematical assumptions are made so that the deformation of the shell is expressed in terms of a single unknown function of position along the shell axis, which is determined in accordance with a variational statement of the equations of motion. Separation of material is represented by a Dugdale zone of localized yielding, in which a critical opening displacement is attained for fracture. With these approximations, the required decay length of the pressure distribution necessary to drive the crack, for a given exit plane pressure and decay shape, and the profile of the opened fracture, are estimated. Inertial effects due to the shell walls and backfill and crack arrest by branching are discussed, although it is pointed up that a complete analysis must await further progress on the fluid dynamics of gas escape through the fracture opening.

    Keywords:

    crack propagation, pipe lines, fracture properties, stresses, strains, plastic deformation


    Author Information:

    Freund, LB
    Professor, Brown University, Providence, R.I.

    Parks, DM
    Assistant Professor, Yale University, New Haven, Conn.

    Rice, JR
    Professor, Brown University, Providence, R.I.


    Paper ID: STP33950S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP33950S


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