Bewertung der Schwingfestigkeit von Schweißnahtenden mit dem Kerbspannungskonzept und bruchmechanischen Methoden∗

Waterkotte, Ralf; Baumgartner, J. Craig; Ai, Qingfeng

doi:10.3139/120.110467

Cited by 5 publications

(2 citation statements)

References 14 publications

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“…It was possible to show, that with the stress averaging approaches an assessment of both failure from weld toe and weld root could be considered with one reference SN‐curve using a micro‐structural length of ρ* = 0.125 mm and the von Mises stress hypothesis. Furthermore, the stress averaging approach was applied for steel weldments, using the micro‐structural length of ρ* = 0.40 mm and maximum principal stresses . Based on fatigue tests and calculated notch stresses Zhang identified a micro‐structural length of ρ* = 0.31 mm by using analytical support factors derived from the Neuber formula .…”

Section: Fatigue Assessment Approachesmentioning

confidence: 99%

Fatigue assessment of joints using the local stress field

Schmidt

Baumgartner

Melz

2015

Materialwissenschaft Werkst

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This paper comprises a brief methodical analysis as well as a practical application of both, the stress averaging approach according to Neuber and the critical distance approach according to Taylor for a fatigue assessment on welded and adhesively bonded thin-walled steel structures. The approaches are discussed and in case of the welded joints compared to the notch stress approach with a reference radius of r(ref) = 0.05 mm, which is usually applied for thin-walled structures. Furthermore, both approaches are applied for an assessment of welded joints and adhesively bonded joints. Using results from fatigue tests, a micro-structural length of * = 0.5 mm could be identified for welds, and * = 2.75 mm for the examined adhesive bonds. The value for steel welds is close to the proposed value of * = 0.4 mm, which was used by Radaj deriving the effective notch radius of r(ref) = 1 mm. For the critical distance approach, a distance of a* = 0.1 mm was derived for welds and a* = 0.9 mm for the examined adhesive bonds. Using the stress averaging or critical distance approach and the identified material values, a reliable fatigue strength assessment can be performed for both welded and adhesively bonded joints

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Section: Fatigue Assessment Approachesmentioning

confidence: 99%

Fatigue assessment of joints using the local stress field

Schmidt

Baumgartner

Melz

2015

Materialwissenschaft Werkst

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“…In addition, stress intensity factors were determined with XFEM calculations in ABAQUS . Simplifying, a plain and elliptical crack at a distance of 0.01 mm from the seam transition notch was used due to numerical reasons, Fig .…”

Section: Experimental Investigationsmentioning

confidence: 99%

Crack initiation and propagation analysis at welds – assessing the total fatigue life of complex structures

Baumgartner

Waterkotte

2015

Materialwissenschaft Werkst

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The fatigue strength of complex welded structures may differ highly from that of a simple test specimen. The reason for this observation is in most cases the high amount of crack propagation on the total fatigue life. The aim of this work is to describe the complex failure mechanism with a two-phase model. In this model, the crack initiation and crack propagation phase are assessed separately. The fatigue life until initiation of a crack is derived by notch stresses, calculated using stress averaging or the critical distance approach. The macro crack propagation is determined by fracture mechanics. The methods, which are available to determine the fatigue life until crack initiation, lead to reliable results. The determination of stress intensity factors proved to be demanding. Variations were observed depending on the calculation approach used. For application in industry, the applied approaches should be improved further.Keywords: Weld start and stop position / crack initiation / crack propagation Das Schwingfestigkeitsverhalten von komplexen Bauteilen unterscheidet sich in vielen Fällen stark von dem einfacher Proben. Diese meist im Abgleich zwischen Berechnung und experimenteller Prüfung gemachte Beobachtung kann häufig über den hohen Anteil des Rissfortschritts an der Gesamtlebensdauer erklärt werden. Ziel dieses Beitrags ist es, das komplexe Schwingfestigkeitsverhalten über ein zwei-Phasen Modell zu beschreiben, in dem die Anriss-und die Rissfortschrittsphase separat betrachtet werden. Die Anrissschwingspielzahl wird hierbei über den Spannungsmittelungs-und Spannungsabstandsansatz berechnet, die anschließende Rissfortschrittsphase über bruchmechanische Methoden. In einer Gegenüberstellung von experimentell ermittelter und berechneter Lebensdauer zeigte sich eine gute Übereinstimmung für das Versagenskriterium technischer Anriss. Bei der bruchmechanischen Bewertung erwies sich die Berechnung der Spannungsintensitätsfaktoren als nicht trivial. Für die industrielle Anwendbarkeit empfiehlt sich daher eine Erweiterung und Optimierung der zur Verfügung stehenden numerischen Werkzeuge. Mat.-wiss. u. Werkstofftech. 2015, 46, No. 2 Crack initiation and propagation analysis at welds

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Fatigue assessment of welded joints using stress averaging and critical distance approaches

et al. 2015

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This paper comprises a brief methodical analysis and practical application of both the stress averaging approach according to Neuber and the critical distance approach according to Taylor for a fatigue assessment on welded steel structures under axial loading. The stress averaging approach, as established theoretically by Neuber, is discussed and compared to the effective notch stress approach with a reference radius r(ref)=1 mm and also to the r(ref)=0.05 mm concept which is usually applied for thin-walled structures. Furthermore, both approaches are applied for an assessment of 38 individual test series. As a result of the evaluations, a microstructural length rho*=0.40 mm is recommended. For the critical distance approach, a distance a=0.10 mm was derived. Fatigue design ( FAT) values are recommended for the practical application. Compared to the notch stress approach with a radius r(ref)=0.05 mm, it was possible to improve the assessment quality significantly. The non-local approaches should be preferred to the r(ref)=0.05 mm concept, especially for welded components using thin sheets for which the radius of 1 mm cannot be applied

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Bewertung der Schwingfestigkeit von Schweißnahtenden mit dem Kerbspannungskonzept und bruchmechanischen Methoden∗

Cited by 5 publications

References 14 publications

Fatigue assessment of joints using the local stress field

Fatigue assessment of joints using the local stress field

Crack initiation and propagation analysis at welds – assessing the total fatigue life of complex structures

Fatigue assessment of welded joints using stress averaging and critical distance approaches

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