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The estimation of the damage and fatigue life of spot welds in vehicle components with hundreds or thousands thereof within reasonable computation time is a challenge even for recent computers in automotive industry. Hence, an advanced procedure in the frequency-domain is proposed. Whereas the general frequency-domain approach is well-established, it nevertheless becomes efficient for a large number of spot welds only with a package of measures. Among others, a two-scale FE-method using a pre-processed data base for various spot weld/sheet geometries and specified basic load cases, application of the cutting-plane method, and a priori stress estimations to reduce the number of spot welds to be checked completely are suggested. By the example of a tank of a cooling medium in a vehicle it is shown that the proposed algorithm may reduce the computation time as compared to time-domain calculations substantially. Effiziente Frequenzbereichs-Methode zur Abschätzung der Ermüdungsfestigkeit von Schweißpunkten in Fahrzeugkomponenten Zusammenfassung Eine rechenzeitgünstige Lebensdauerabschätzung einer großen Anzahl von Schweißpunkten in Fahrzeugkomponenten stellt auch für moderne Computer eine Herausforderung dar. Es wird deshalb eine neue Vorgehensweise im Frequenzbereich vorgeschlagen. Während die allgemeine Methode wohlbekannt ist, wird sie für große Anzahlen von Schweißpunkten dennoch erst durch mehrere Zusatzmaßnahmen effizient. Es werden unter anderem eine Zweiskalen-FE-Methode unter Verwendung einer Datenbank für diverse Schweißpunkt-/Blechgeometrien unter definierten Einheits-Belastungen vorgeschlagen, Anwendung der Schnittebenenmethode und A-priori-Spannungsabschätzungen zur Reduktion der vollständig zu untersuchenden Schweißpunkte. Am Beispiel eines Kühlmitteltanks in einem Fahrzeug wird gezeigt, daß die vorgeschlagene Vorgehensweise eine signifikante Rechenzeitreduktion gegenüber Zeitbereichs-Berechnungen ermöglicht.

Plane stress and plane strain analytical solutions to partially plastic deformation of a curved beam are presented. The beam has a narrow rectangular cross section and it is subjected to couples at its end sections prevailing pure bending conditions. The analysis is based on Tresca's yield criterion, its associated flow rule and linear strain hardening material behavior. The solutions are verified in comparison to the ones available in the literature. It is shown that plane stress and plane strain solutions agree well in the elastic and in the elastic-plastic deformation stages. It is also observed that the changes in the dimensions of the beam as it deforms are negligibly small. Nomenclature a, binner and outer radii of the curved beamcylindrical polar coordinates (dimensionless radial coordinate r = r/a) r NA radial coordinate of the neutral axis r i radial coordinate of elastic-plastic interface (i = 1, 2) t r , t z thickness of the beam in rand z-directions u radial displacement component (dimensionless form u = uE/(σ 0 b)) θ s subtended angle of the beam (Fig. 1)Poisson's ratio γ rθ shear strain component (normalized form γ rθ = γ rθ E/σ 0 ) j normal strain component in j-direction (normalized form j = j E/σ 0 ) EQ equivalent plastic strain σ 0 , σ Y initial and subsequent yield stress σ j normal stress component in j-direction (dimensionless form σ j = σ j /σ 0 ) τ rθ shear stress component

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