STP627

    Computation of Crack Propagation and Arrest by Simulating Microfracturing at the Crack Tip

    Published: Jan 1977


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    Abstract

    This paper describes the initial development stages of a computational capability for fast fracture and arrest, based on treatment of plastic flow and microfracturing at the crack tip. The approach is to model the events occurring within the process zone, compute the associated energies, and thereby determine the fracture toughnesses of propagating and arresting cracks.

    The model treats crack propagation as occurring by the nucleation, growth, and coalescence of microfractures in the plastically deforming material at the crack tip. It uses as input actual measurements from specimens fractured under stress wave loads. The dynamic stress history experienced by this material is calculated by a two-dimensional wave propagation code.

    The approach was demonstrated by performing a computational simulation of a Battelle double-cantilever-beam crack arrest experiment and calculating the energies absorbed in plastic flow and microfracturing. Plastic work accounted for about 95 percent of the fracture toughness, but microfracture activity controls the amount of plastic work that is done and hence governs the toughness. Agreement between computed and observed crack velocity and arrest length is not yet satisfactory but should improve when a finer computational grid is used.

    The approach offers an avenue for understanding fracture toughness on a micro-level by linking micromechanical material response to continuum toughness parameters.

    Keywords:

    crack propagation, microfracturing, crack initiation, fracture properties, crack arrest, stress intensity, velocity


    Author Information:

    Shockey, DA
    Assistant manager, senior research engineer, and manager, Shock Physics and Geophysics Group, Poulter Laboratory, Stanford Research Institute, Menlo Park, Calif.

    Seaman, L
    Assistant manager, senior research engineer, and manager, Shock Physics and Geophysics Group, Poulter Laboratory, Stanford Research Institute, Menlo Park, Calif.

    Curran, DR
    Assistant manager, senior research engineer, and manager, Shock Physics and Geophysics Group, Poulter Laboratory, Stanford Research Institute, Menlo Park, Calif.


    Paper ID: STP27393S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP27393S


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