Notch stress formulae are derived for the application of a notch stress approach to the fatigue assessment of spot welds. A keyhole notch is assumed to describe the edge of the weld spot between the overlapping plates. The stress fields at the keyhole notch under ‘singular’ and ‘non‐singular’ in‐plane loading modes inclusive of the stress concentration factors Kt are derived from the relevant Airy stress functions. The formulae are applied to typical loading cases of spot welds and compared with finite element solutions. Fatigue‐effective notch stresses inclusive of fatigue notch factors Kf are calculated by applying the microstructural support hypothesis of Neuber. The notch stresses at the keyhole are also derived for out‐of‐plane shear loading based on the relevant harmonic stress functions. The multiaxial notch stresses at the weld spot edge are thus completely described.

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Abriß der Problemstellung und verfügbare Verfahren der Lebensdauerberechnung bei Schwingbeanspruchung. Der Grundgedanke der Amplituden‐Transformation auf der Grundlage linearer Schadensakkumulation. Definition eines Schädigungskennwertes aus der Hystereseschleife der örtlichen Spannung und Dehnung im Kerbgrund. Erzielte Verbesserungen der Lebensdauervorhersage, veranschaulicht anhand von Beispielen.

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