Fatigue resistance of weld ends – Analysis of the notch stress using real geometry

Kaffenberger, Matthias; Vormwald, Michael

doi:10.1002/mawe.201100849

Cited by 17 publications

(23 citation statements)

References 10 publications

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“…The modelling steps of such an idealised weld end geometry are comprehensively described in [1][2][3][4][5][6]. A submodelling technique has been used, in order to calculate the von Mises equivalent stresses.…”

Section: Notch Stressesmentioning

confidence: 99%

“…Normally, fatigue design of welded components proceeds from S-N curves (fatigue strength versus number of cycles). Concerning weld start and end points, the knowledge of S-N curve parameters is limited to either normal [1][2][3][4][5] or shear [6] stressed structures. In these investigations, dealing only with uniaxial loading conditions, geometrically idealised weld end models with concept radii of r normal = 0.20 mm respectively r shear = 0.05 mm were created.…”

Section: Introductionmentioning

confidence: 99%

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Sharp three-dimensional notches under combined nominal normal and shear fatigue loading

Vormwald¹,

Shams²

2017

Frattura Ed Integrità Strutturale

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ABSTRACT. Many engineering structures are exposed to non-proportional fatigue loading. However, at the critical location of crack initiation, often only one of the load sequences dominates -the individual load cases result in different crack initiation sites. Based on engineering judgment a simplified local uniaxial or proportional loading situation may be assessed. In general, the critical location must be identified by calculating fatigue lives for a variety of locations. The position of the critical location depends on the hypothesis applied for life calculation -besides loading, geometry, material and many other influence factors. For sharp three-dimensional notches the region for the search of the critical location may be restricted considerably. Weld start and stop points are an industrial example for such sharp notches. They are the object of the present investigation. They are exposed to nominal normal and shear loading. The individual hot spots for crack initiation lie necessarily close together. A strong interaction of the loading cases for both proportional and non-proportional loading was experimentally observed. In the numerical investigation notch stresses were calculated using an idealised weld end model. Based on the critical plane approach according to Findley, numerical interaction lines were produced.

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Section: Notch Stressesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Sharp three-dimensional notches under combined nominal normal and shear fatigue loading

Vormwald¹,

Shams²

2017

Frattura Ed Integrità Strutturale

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“…Im numerischen Arbeitspaket wurden Kerbspannungen für die Einheitslastfälle Normalkraft und Torsionsmoment basierend auf einem idealisierten Nahtendmodell mittels der Finite‐Elemente‐Methode (FEM) berechnet. Nähere Informationen zum Nahtendmodell können der Literatur entnommen werden . Die Geometrie des Nahtendes weist einen Nahtwurzelradius von 0,05 mm und einen Nahtübergangsradius von 0,2 mm auf.…”

Section: Numerische Analysenunclassified

“…Heute liegen Konzepte zur Schwingfestigkeitsbewertung von Nahtenden in zug‐ und schubbeanspruchten Nahtenden vor . Hierbei wurden idealisierte FE‐Nahtendmodelle für beide Lastfälle entwickelt.…”

Section: Introductionunclassified

Schwingfestigkeitsbewertung von Nahtenden unter kombinierter Beanspruchung

Shams

Vormwald

2016

Materialwissenschaft Werkst

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In dieser Arbeit wird eine Methode zur Berechnung der Schwingfestigkeit von Nahtenden in Feinblechstrukturen unter kombinierter Normal‐ und Schubbeanspruchung basierend auf Kerbspannungen vorgestellt. Die Berechnung der Kerbspannungen erfolgte mit Hilfe der Methode der Finiten Elemente unter Zuhilfenahme der Submodelltechnik. Ein idealisiertes Nahtendmodell wurde verwendet, um die Beanspruchungssituation für solche Lastsituationen zu bewerten. Zudem wurde unter Einsatz eines Berechnungsverfahrens Größeneinflüsse zweier Arten, zum einen der spannungsmechanische und zum anderen der statistische Größeneinfluss, berücksichtigt. In Verbindung mit Bruchschwingspielzahlen aus Schwingversuchen wurde eine konzeptgebundene Kerbspannungswöhlerlinie ermittelt. Somit liegt erstmalig eine Bewertungsmethode nach dem Kerbspannungskonzept für die Schwingfestigkeit von Nahtenden unter kombinierter Beanspruchung vor.

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“…With the increasing application of theoretical concepts into the development process of engineering structures, the demand for experimental evidence referring to their reliability and robustness is also growing. Taking Kaffenberger's comprehensive experimental database of thin‐welded specimens into account, the present paper contains a state‐of‐the‐art comparison between the most common fatigue concepts contained in the IIW guideline and proposes simple procedures to extend their applicability to thin structures providing pronounced weld terminations.…”

Section: Introductionmentioning

confidence: 99%

Fatigue assessment of thin‐welded joints with pronounced terminations

Malikoutsakis

Savaidis

2014

Fatigue Fract Eng Mat Struct

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A B S T R A C T The present paper reviews and contains simple modifications to extend the applicability of global and local fatigue concepts to thin-welded specimens with pronounced weld terminations (starts/ends). Experimental fatigue data reported by Kaffenberger and Vormwald have been used for the validation of the proposed procedures. Special attention is paid to the notch strain concept. The material state is explicitly considered by means of corresponding strain-life curves in conjunction with P SWT , P Morrow or the experimental mean stress sensitivity factors proposed by Olivier. The accuracy of Neuber's sharp and mild notch formulas, Seeger-Beste's formulation and Glinka's strain energy density rule within the context of the notch strain approach has been investigated. Simple rules accounting for stress relaxation effects have been additionally proposed and implemented into the calculations. Comparison of experimental with theoretical fatigue lives validates the accuracy and robustness of the proposed procedures to calculate fatigue design S-N curves.Keywords fatigue; effective notch stress; notch strain approach; thin-welded joints; weld terminations. N O M E N C L A T U R EA [%] = elongation at fracture a * [mm] = micro-structural support length A nom [mm 2 ] = nominal sheet area A w [mm 2 ] = nominal weld area b = fatigue exponent c = ductility exponent c f = fatigue notch factor (expressed versus nominal loads) c t = elastic notch factor (expressed versus nominal loads) e* = nominal strain ENSC = effective notch stress concept FAT = fatigue assessment curves FEA = finite element analysis FE = finite element FKM = Forschungskuratorium Maschinenbau HAZ = heat affected zone HCF = high cycle fatigue HRA = Rockwell-A hardness IIW = International Institute of Welding K ' [N/mm 2 ] = cyclic hardening coefficient K f = fatigue notch factor (expressed versus nominal stresses) K p = fully plastic limit factor K t = elastic notch factor (expressed versus nominal stresses) L [N] = nominal load LCF = Low Cycle Fatigue L w [mm] = weld length m = slope Correspondence: Michail Malikoutsakis.

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Fatigue resistance of weld ends – Analysis of the notch stress using real geometry

Cited by 17 publications

References 10 publications

Sharp three-dimensional notches under combined nominal normal and shear fatigue loading

Sharp three-dimensional notches under combined nominal normal and shear fatigue loading

Schwingfestigkeitsbewertung von Nahtenden unter kombinierter Beanspruchung

Fatigue assessment of thin‐welded joints with pronounced terminations

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