Effect of Periodic Overloads on Threshold Fatigue Crack Growth in Al-Alloys

    Volume 2, Issue 1 (January 2005)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 3 January 2005

    Page Count: 16


    Sunder, R
    BiSS Research, Bangalore,

    (Received 17 November 2003; accepted 6 April 2004)

    Abstract

    Experiments were performed on 10 mm thick C(T) specimens cut from Al-alloys to assess fatigue crack growth behavior under periodic overloads by comparison to constant amplitude loading. The tests were performed at a sufficiently high stress ratio to avoid crack closure, whose absence was confirmed from Load-COD response. ΔKth values were determined under these loadings in air, salt water, and vacuum. Even though closure was absent, ΔKth shows a systematic dependence on overload plastic zone ratio. Similar results were obtained in both air and salt water. In vacuum however, near threshold crack growth is accelerated by comparison to no-overload conditions, while higher growth rates see a reversal in this trend. These results appear to support the possibility that residual stress moderates crack-tip surface chemistry in near-threshold fatigue, an effect that ceases in vacuum.


    Paper ID: JAI12004

    DOI: 10.1520/JAI12004

    ASTM International is a member of CrossRef.

    Author
    Title Effect of Periodic Overloads on Threshold Fatigue Crack Growth in Al-Alloys
    Symposium Fatigue and Fracture Mechanics: 34th Volume, 2003-11-21
    Committee E08