STP1074: Application of the CEGB Failure Assessment Procedure, R6, to Surface Flaws

    Chell, GG
    Central Electricity Research Laboratories, Leatherhead, Surrey

    Pages: 20    Published: Jan 1990


    Abstract

    The application of the R6 failure assessment procedure to surface flaws requires the definition of a plastic yield load that characterizes the crack tip deformation at both the deepest and surface points on the defect. In this paper the results of finite element computations of the J-integral are used to identify the most appropriate yield loads. This is achieved by assuming that the Option 2 failure assessment diagram (FAD), which is based on a reference stress approximation to J, provides a good approximation to the Option 3 FAD, which is derived from the computed J values. The finite element results for surface flaws in plates and cylinders are used in the investigation. It is demonstrated that global yield loads, which characterize the overall plastic deformation of the cracked structure, produce a better agreement between the R6 procedure, and the finite element solutions, than do local yield loads, which are usually chosen to characterize the plastic deformation at a specific location on the crack front.

    Keywords:

    R6 procedure, surface flaws, failure assessment diagram, J, -integral, plastic yield load, cracked structures, elastic-plastic fracture, failure analysis


    Paper ID: STP19012S

    Committee/Subcommittee: E08.04

    DOI: 10.1520/STP19012S


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