In-situ Fatigue Damage Investigations in Welded Metallic Components by Infrared Techniques

    Volume 5, Issue 9 (October 2008)

    ISSN: 1546-962X

    CODEN: JAIOAD

    Published Online: 28 October 2008

    Page Count: 18


    Medgenberg, Justus
    Technische Universitaet Carolo-Wilhelmina, Braunschweig,

    Ummenhofer, Thomas
    Technische Universitaet Carolo-Wilhelmina, Braunschweig,

    (Received 6 November 2007; accepted 1 August 2008)

    Abstract

    The paper reviews the state of the art of thermal damage assessment in metals and proposes a specialized form of lock-in thermography as an efficient tool for the quantification of early fatigue damage phenomena in welded steel structures in the regime of mid- to high-cycle fatigue. It can be proved that advanced thermographic techniques are sensitive to early damage phenomena in the weld toe. They provide a new experimental mean for in-situ investigation of early inhomogeneous fatigue damage phenomena as mesoplasticity and fatigue cracks. The results demonstrate that non-contacting full field temperature measurements using highly sensitive infrared technology can be applied successfully to detect localized fatigue damage at around 10 % to 20 % of the total fatigue lifetime of the tested specimens. The applied method is based on the separation of thermoelastic and thermoplastic temperature effects which cause characteristic local temperature signatures. In contrast to other well-known approaches—as, e.g., measuring the rise of mean temperature during fatigue loading—the applied method offers a very high spatial resolution and resolves extremely localized phenomena. The methodology can be applied to monitor the fatigue process during conventional fatigue testing. The additional effort for the specimen preparation and the installation of the testing setup is minimal.


    Paper ID: JAI101523

    DOI: 10.1520/JAI101523

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    Author
    Title In-situ Fatigue Damage Investigations in Welded Metallic Components by Infrared Techniques
    Symposium Seventh International ASTM/ESIS Symposium on Fatigue and Fracture Mechanics (36th ASTM National Symposium on Fatigue and Fracture Mechanics), 2007-11-16
    Committee A01