Computer-Controlled Stress Intensity Gradient Technique for High Rate Fatigue Crack Growth Testing

    Volume 8, Issue 1 (January 1980)

    ISSN: 0090-3973

    CODEN: JTEOAD

    Page Count: 6


    Donald, JK
    Vice-president and staff engineerMembers of ASTM, Del Research Division, PSC Professional Services Group, Inc., Hellertown, Pa.

    Schmidt, DW
    Vice-president and staff engineerMembers of ASTM, Del Research Division, PSC Professional Services Group, Inc., Hellertown, Pa.

    Abstract

    An automated test system utilizing a computer for data acquisition and machine control was used to obtain crack growth rate data from 2.5 × 10−8 to 2.5 × 10−6 m/cycle (1 × 10−6 to 1 × 10−4 in./cycle) on a compact type specimen. The crack length was monitored continuously by using the elastic compliance technique, enabling the stress intensity K to be increased according to the equation ΔK = ΔK exp [C(aa0)] (where a0 and a are the initial and instantaneous crack lengths and C is a test variable). Crack growth data were obtained on a Ni-Cr-Mo-V rotor steel by using both different, programmed K gradients and the more conventional constant-load-amplitude method where the stress intensity increases as a function of increasing crack length. Excellent agreement was observed between the two test procedures.


    Paper ID: JTE10588J

    DOI: 10.1520/JTE10588J

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    Author
    Title Computer-Controlled Stress Intensity Gradient Technique for High Rate Fatigue Crack Growth Testing
    Symposium , 0000-00-00
    Committee E28