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Über den Einfluß von Eigenspannungen, Nahtgeometrie und mehrachsigen Spannungszuständen auf die Betriebsfestigkeit geschweißter Konstruktionen aus Baustählen

Parallelausgabe: Betriebsfestigkeit in Forschung, Lehre und Praxis. Bericht - Verein Deutscher Eisenhüttenleute Nr. ABF 55 (1992), S.139-157.
: Sonsino, C.M.


Materialwissenschaft und Werkstofftechnik 25 (1994), No.3, pp.97-109 : Abb.,Lit.
ISSN: 0933-5137
Journal Article
Fraunhofer LBF ()
Baustahl; Betriebsfestigkeit; Eigenspannung; Kerbwirkung; Mehrachsigkeit; multiaxial stress-state; notch effect; residual stress; Schweißverbindung; structural fatigue strength; structural steel; welded joint

The fatigue behaviour of welded joints depends primarely on the interaction between notch geometry, residual stress and type of loading, i.e. constant and variable amplitude loading. Longitudinal stiffeners respond to a thermal stress relieving with an increase of endurance limit of about 50 percent; but in the finite fatigue life region due to plastifications in the sharp weld notch root there is no difference between the as/welded state and the stress relieved state. The plastifications are the reason that also under variable amplitude loading only in the region of high cycles a slight improvement of about 15 percent due to the thermal treatment was observed. However, in the case of V-shaped specimens with smooth weld radii a stress relieve results for the whole S-N-curve in an increase of about 56 percent and under variable amplitude loading for the whole fatigue life curve in an improvement of 33 percent. A TIG-dresesing improves the fatigue strength under variable amplitude loadin g by a further 53 percent. Concerning multiaxial fatigue, when principal stress directions are constant the von Mises hypothesis can be applied satisfactorily. However, for changing stress directions all conventional hypotheses (von Mises, Tresca, principal stress) severely over-estimate the fatigue life. Therefore, a development of strength hypotheses is necessary.