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Fatigue life assessment of improved joints welded with alternative welding techniques
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.ORCID iD: 0000-0003-4465-9299
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Lightweight Structures.ORCID iD: 0000-0003-4180-4710
2014 (English)In: Engineering Failure Analysis, ISSN 1350-6307, Vol. 42, 10-21 p.Article in journal (Refereed) Published
Abstract [en]

In this study, the fatigue life improvement by adopting the toe weaving technique on non-load carrying cruciform welded joints has been investigated. Fatigue testing was conducted on two batches of specimens welded using double-pass manual welding. One batch had a straight second pass and the other was weaved. The influence of different weaving shape parameters was analyzed by performing crack growth analyses. The fatigue testing shows a slightly improved fatigue life for the two different batches compared to as- welded joints; the improvement is similar for both batches. The crack growth analysis concludes that the batch with the straight second pass should provide slightly higher fatigue life compared to the toe weaved batch. Measurements show a presence of undercuts in the vicinity of the crack initiation site. Nonetheless, an increased fatigue life is obtained, due to the low flank angle created during welding of the second pass, which reduces the stress concentration in the weld toe, prolonging the fatigue life.

Place, publisher, year, edition, pages
2014. Vol. 42, 10-21 p.
National Category
Vehicle Engineering
URN: urn:nbn:se:kth:diva-147405DOI: 10.1016/j.engfailanal.2014.03.012ISI: 000336660400002ScopusID: 2-s2.0-84897030872OAI: diva2:731664

QC 20140702

Available from: 2014-07-02 Created: 2014-06-27 Last updated: 2016-06-13Bibliographically approved
In thesis
1. Fatigue properties of cut and welded high strength steels: Quality aspects in design and production
Open this publication in new window or tab >>Fatigue properties of cut and welded high strength steels: Quality aspects in design and production
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This doctoral thesis concerns fatigue of welded structures. Welding is one of the world’s most common joining methods and it is frequently used in several structural applications in many fields. Some examples are construction vehicles, loader cranes, trucks, busses, forestry and agricultural machines, bridges and ships. Since these structures are subjected to repeated loading, fatigue is the most common cause of failure.

A novel numerical algorithm has been developed which assesses the welded surface and calculates and quantifies weld quality parameters and the presence of defects which are critical in fatigue applications. The algorithm is designed for implementation in serial production. It will provide robust and reliable feedback on the quality being produced, which is essential if high strength steels are utilized.

Two welding procedures which can increase the weld quality in as welded conditions have been assessed. These procedures utilize welding in different positions and pendling techniques, which can be accomplished using the existing welding equipment. It was found that by using these methods, the fatigue strength can be increased compared to normal weld quality.

Furthermore, two fatigue assessment methods ability to account for increased weld quality in low cycle and high cycle fatigue applications has been studied. One of these methods showed sufficient accuracy in predicting the fatigue strength with small scatter and also account for increased weld quality.

When implementing thinner high strength steels, the overall stress level in the structure increase. Therefore, other locations such as the steel cut edges may become critical for fatigue failure unless they are not designed and manufactured with the same quality as the welded joint. The influence of surface quality on cut edges was studied and the fatigue strength was estimated using international standards and a fatigue strength model for cut edges.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2016. 56 p.
TRITA-AVE, ISSN 1651-7660 ; 2016:21
Welding, Fatigue assessment, Cutting, Weld quality, Fatigue design, Fracture Mechanics
National Category
Vehicle Engineering
Research subject
Vehicle and Maritime Engineering
urn:nbn:se:kth:diva-188225 (URN)978-91-7729-027-8 (ISBN)
Public defence
2016-08-26, F3, Lindstedtsvägen 26, Stockholm, 09:00 (English)

QC 20160613

Available from: 2016-06-13 Created: 2016-06-09 Last updated: 2016-06-13Bibliographically approved

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Holmstrand, ThomasMrdjanov, NikolaBarsoum, Zuheir
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