The applicability of and the quality of assessment using the nominal stress, structural stress and notch stress approaches for calculating the fatigue strength of laser beam welded components made of thin steel sheets has been investigated. For this purpose, the fatigue lives of a longitudinal carrier, an injector and two tube-flange specimens have been determined by tests under constant amplitude loading. Fatigue cracks initiated at sharp root notches on all of these components. While the nominal stress is derived by theory of structural mechanics, the determination of structural and notch stresses is performed using 3D finite element models and solid elements. The structural stress is derived by an extrapolation of surface stress to the fatigue critical notch and the notch stresses by rounding the sharp root notch with a reference radius of rref = 0.05 mm. For all of the concepts used, the endurable stresses have been compared to the design SN-curves recommended by the International Institute of Welding (IIW). On comparing the quality of assessment of the different concepts, the notch stress approach shows the highest scatter. The highest endurable notch stresses occur in specimens with crack initiation at weld ends. These specimens have a very small highly loaded weld length. The lowest endurable stresses are determined for specimens with a long, equally loaded weld. The reason for these findings can be explained by statistical size effects. For an improved fatigue assessment, an easily applicable method is introduced, which takes into account the highly stressed weld length.


    Access

    Access via TIB

    Check availability in my library

    Order at Subito €


    Export, share and cite



    Title :

    Fatigue strength of laser beam welded automotive components made of thin steel sheets considering size effects


    Additional title:

    Ermüdungsfestigkeit lasergeschweißter Automobilkomponenten aus dünnen Stahlblechen unter Berücksichtigung von Größeneffekten


    Contributors:
    Baumgartner, J. (author) / Bruder, T. (author) / Hanselka, H. (author)

    Published in:

    Publication date :

    2011


    Size :

    11 Seiten, 12 Bilder, 3 Tabellen, 25 Quellen




    Type of media :

    Article (Journal)


    Type of material :

    Print


    Language :

    English




    Fatigue of Automotive High Strength Steel Sheets and Their Welded Joints

    Takahashi, Isao / Shinozaki, Masatoshi / Irie, Toshio et al. | SAE Technical Papers | 1983


    Fatigue of Automotive High Strength Steel Sheets and Their Welded Joints

    Shinozaki,M. / Kato,T. / Irie,T. et al. | Automotive engineering | 1983


    Determine Member Strength of Automotive Steel Components Considering Local Buckling Effects

    Prince, Douglas G. / Errera, Sam / Wang, Shiunn-Jang | SAE Technical Papers | 2000


    Determine member strength of automotive steel components considering local buckling effects

    Wang,S.J. / Errera,S. / Prince,D.G. et al. | Automotive engineering | 2000


    Fatigue strength of laser beam welded magnesium alloys

    Haferkamp,H. / von Alvensleben,F. / Goede,M. et al. | Automotive engineering | 1999