The structural stress approach has been applied to the fatigue strength assessment of fillet welds mainly subjected to throat bending. Such load situations occur for instance in axially-loaded structures with one-sided fillet welds or at fillet-welded cover plates with out-of-plane loads. The local bending of the fillet welds usually causes fatigue cracks initiating from the weld root. The linearised structural stress in the weld leg section extending from the non-fused root face is considered as relevant parameter for the fatigue damage. The weld leg plane is chosen because the path of fatigue cracks was found to be closer to this plane than to the throat section in fillet welds being mainly subjected to throat bending. The shear stresses are small in the considered cases. In other cases, this can be checked to avoid the approach to be applied to welds subjected to high shear forces because these may cause a different crack path and failure behaviour. The fatigue assessment of fillet welds subjected mainly to bending should be performed as follows: 1. Normally, the structural weld stress is determined from a finite element model using either the nodal forces in the weld leg section or in the throat section. Nodal forces should be preferred to finite element stresses, because the latter are affected by the stress singularity at the weld root. 2. Alternatively, the structural weld stress can be determined in structures with one-sided welds from the stresses in the attached plate by equilibrium conditions. This allows finite element models established for the evaluation of structural stresses to be used also for the determination of the structural stress in the welds. 3. The fatigue strength regarding root failure can be determined using the above defined structural weld stress together with the design S-N curve FAT 80 according the IIW fatigue design recommendations. In view of the relatively small number of specimens analysed, additional investigations are felt to be necessary in order to verify the approach. Still unclear is the question, how far the results are influenced by the thickness effect as well as by welding residual stresses.


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    Titel :

    Fatigue assessment of root cracking of fillet welds subject to throat bending using the structural stress approach


    Beteiligte:
    Fricke, W. (Autor:in) / Kahl, A. (Autor:in) / Paetzold, H. (Autor:in)

    Erschienen in:

    Welding in the World ; 50 , 7/8 ; 64-74


    Erscheinungsdatum :

    2006


    Format / Umfang :

    11 Seiten, 12 Bilder, 6 Tabellen, 12 Quellen



    Medientyp :

    Aufsatz (Zeitschrift)


    Format :

    Print


    Sprache :

    Englisch




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