STP1389

    Local Approach to Dynamic Fracture Toughness Evaluation

    Published: Jan 2000


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    Abstract

    Fracture toughness properties of structural steels of 490-MPa strength class and weld metals under dynamic loading are studied in the light of the near crack tip stress fields. The loading rate in toughness tests range from 0.1 to 500 mm/s. The near-tip stress fields are analyzed by 3D-FEM considering the strain rate effect on the flow properties of materials. Temperature rise caused by high-speed plastic deformation is also included in the FE analysis. The critical CTOD at brittle fracture initiation decreases when increasing the loading rate. This is due to the elevation of a local stress near the crack tip. The local approach is applied to the dynamic fracture toughness evaluation. It is shown that the brittle fracture resistance evaluated in terms of the Weibull stress, an integrated stress over a highly stressed region near the crack tip, is a material property independent of the loading rate. Based on the Weibull stress fracture criterion, the dynamic fracture toughness can be predicted from static toughness results. An engineering procedure to estimate the loading rate effect on the fracture toughness is also presented.

    Keywords:

    dynamic fracture toughness, CTOD, brittle fracture, structural steels, weld metals, Local Approach, Weibull stress, rate-temperature parameter, 3D dynamic FEM


    Author Information:

    Minami, F
    Associate professor and graduate student, Graduate School of Engineering, Osaka University, Osaka,

    Ochiai, T
    Structural department manager, Katayama Stratech Corporation, Osaka,

    Hashida, T
    Structural department manager, Katayama Stratech Corporation, Osaka,

    Arimochi, K
    Principal researcher and senior research engineer, Corporate Research and Development Laboratories, Sumitomo Metal Industries Ltd., Amagasaki,

    Konda, N
    Principal researcher and senior research engineer, Corporate Research and Development Laboratories, Sumitomo Metal Industries Ltd., Amagasaki,


    Paper ID: STP14805S

    Committee/Subcommittee: E08.04

    DOI: 10.1520/STP14805S


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