STP675: Direct Observation and Mechanism of Fatigue Crack Propagation

    Kikukawa, M
    Professor, associate professor, and assistant, Osaka University, Suita,

    Jono, M
    Professor, associate professor, and assistant, Osaka University, Suita,

    Adachi, M
    Professor, associate professor, and assistant, Osaka University, Suita,

    Pages: 20    Published: Jan 1979


    Abstract

    Fatigue crack propagation tests were carried out by using a specially designed testing apparatus in a scanning electron microscope. A grain-oriented silicon iron was used as a testing material and it was found that a nearly plane-strain state could be realized up to the specimen surface by selection of the loading axis to the specific orientation of the material. From the sequential observations of crack opening and closure behavior the mechanism of fatigue crack propagation by Mode I opening was confirmed to be an alternating slipping-off process at the crack-tip apex.

    Quantitative evaluation of a relationship between crack-tip opening displacement and crack growth length is given by considering the slip direction, crack tip angle, and the amount of rewelding. Also, a relation between crack growth length and slipped length in Mode II fatigue cracks is discussed.

    Keywords:

    crack propagation mechanism, crack tip angle, crack-tip opening displacement (CTOD), direct observation, fatigue


    Paper ID: STP35892S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP35892S


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