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Fatigue life prediction of welded joints in a complex structure
KTH, Superseded Departments, Aeronautical and Vehicle Engineering.
2002 (English)In: Design and Analysis of Welded High Strength Steel Structures / [ed] Samuelsson, J., 2002Conference paper (Other academic)
Place, publisher, year, edition, pages
National Category
Engineering and Technology
URN: urn:nbn:se:kth:diva-26396ISBN: 1-901537 34 XOAI: diva2:372419
The Eighth International Fatigue Congress FATIGUE 2002, Stockholm, Sweden 3-7 June, 2002

QC 20101125

Available from: 2010-11-25 Created: 2010-11-25 Last updated: 2012-08-23Bibliographically approved
In thesis
1. LEFM analysis and fatigue testing of welded structures
Open this publication in new window or tab >>LEFM analysis and fatigue testing of welded structures
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Fatigue design of welded structures has always been important for construction equipment manufactures. The product development and manufacturing trends are reduction of lead time, cost and LCC. In manufacturing, improved quality assurance system and automated weld processes will reduce scatter and improve the possibilities for lighter structures with improved performance. At present most fatigue analysis is done using the nominal stress method or by structural testing, sometimes with improved concepts as structural stress or effective notch stress. In this thesis methods for fatigue life assessment, with higher accuracy, have been evaluated on frame structures.

The main objectives in this thesis is to investigate the utility of LEFM in fatigue assessment of typical welded structures in construction equipment; to verify the accuracy of LEFM with results from fatigue testing of a complex welded structure and to achieve an better understanding of parameters that influence on crack propagation. The purpose was also to compare different fatigue assessment methods, this has been done to some extent but main part of the work has been on LEFM.

An investigation of the accuracy and efforts in connection with different life prediction methods of welded joints in a complex structure has been done. The investigated structure was a frame to a wheel loader. The life prediction was performed with nominal stress, structural stress, effective notch stress and LEFM. The investigations show a lot of scatter in predicted life for the different methods.

Fatigue analysis and testing of a welded frame has been performed and discussed. The structure contained typical welds for a frame to a wheel loader. A service load spectrum with an overall stress ratio, R, of about -1 was used. The test results were correlated with LEFM including different assumptions of residual stress distributions.

In literature survey information useful in fatigue crack propagation analysis are compiled. The disussed concepts are crack closure, threshold values, crack growth material parameters, mixed mode conditions, variable amplitudes, small cracks and residual stresses.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. v, 11 p.
Trita-AVE, ISSN 1651-7660 ; 2005:20
National Category
Engineering and Technology
urn:nbn:se:kth:diva-271 (URN)91-7178-094-7 (ISBN)
2005-06-09, E3, Lindstedtsvägen 3, Stockholm, 10:15
QC 20101125Available from: 2005-06-07 Created: 2005-06-07 Last updated: 2010-11-25Bibliographically approved

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Byggnevi, Magnus
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