STP1372: Resistance Curves for the Threshold of Fatigue Crack Propagation in Particle Reinforced Aluminium Alloys

    Tabernig, B
    Research assistant and senior scientist, Erich Schmid Institut für Materialwissenschaft der Österreichischen Akademie der Wissenschaften und Institut für Metallphysik der Montanuniversität Leoben, Leoben,

    Powell, P
    Research scientist, Structural Materials Centre, Defence Evaluation and Research Agency, Farnborough, Hampshire

    Pippan, R
    Research assistant and senior scientist, Erich Schmid Institut für Materialwissenschaft der Österreichischen Akademie der Wissenschaften und Institut für Metallphysik der Montanuniversität Leoben, Leoben,

    Pages: 13    Published: Jan 2000


    Abstract

    The threshold of stress intensity factor range ΔKth increases with increasing crack extension until it reaches the constant value of long cracks. Such curves can be interpreted as resistance curves for the threshold of fatigue crack propagation.

    In the paper a very simple method to measure such R-curves is presented and a concept based on the R-curve is used to describe the propagation/non-propagation behavior of physically small cracks. The application of the R-curve technique results in the Kitagawa diagram where one can estimate the fatigue limit of components containing “small” flaws. R-curve tests and standard fatigue experiments at different stress ratios were performed on a 20 vol% SiC particle reinforced 359 T6 cast aluminum alloy which contains naturally small flaws up to 400 μm. Application of the R-curve concept is demonstrated and the estimations are compared with experimental results of the fatigue tests. Good agreement between the predicted and measured failure behavior was found.

    Keywords:

    fatigue threshold, resistance curve, physically small crack, fatigue limit prediction, Kitagawa diagram


    Paper ID: STP13428S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP13428S


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