A Methodology for Assessing Fatigue Crack Growth Reliability of Railroad Tank Cars

    Volume 1, Issue 8 (September 2004)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 30 August 2004

    Page Count: 15


    Zhao, W
    Research Professor and Carolina Distinguished Professor, University of South Carolina, Columbia, SC

    Sutton, MA
    Research Professor and Carolina Distinguished Professor, University of South Carolina, Columbia, SC

    Penã, J
    Mechanical Engineer, US Department of Transportation, Federal Railroad Administration, Washington, DC

    (Received 16 September 2002; accepted 11 July 2003)

    Abstract

    A methodology for assessing structural reliability of railroad tank cars undergoing fatigue crack growth is being developed. A three-degree-of freedom (3-dof) surface crack is employed to account for an asymmetric stress field existing at a fatigue critical location in tank car structures. A fatigue life prediction program using the Walker equation to account for stress ratio effects is developed for the 3-dof surface crack model. A component reliability problem is formulated as a limit state function and solved using a first-order reliability method along with importance sampling method within the commercial reliability software, STRUREL. The methodology is demonstrated using illustrative railroad tank car examples. The results show that: (a) failure probability, Pf, increases as tank car mileage increases; (b) welding residual stresses in the tank structure can significantly increase Pf; (c) uncertainty in the stress amplitude also has a significant effect on Pf; and (d) the correlation between initial crack depth and initial crack aspect ratio is an important parameter.


    Paper ID: JAI11574

    DOI: 10.1520/JAI11574

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    Author
    Title A Methodology for Assessing Fatigue Crack Growth Reliability of Railroad Tank Cars
    Symposium Probabilistic Aspects of Life Prediction, 2002-11-06
    Committee E08