The aim of the investigation was to evaluate the fatigue strength of butt joints welded with the weaving technique in comparison to the string-bead technique as well as the applicability of both welding techniques for large gap widths welded with unfavourable constraints. Despite a small decrease in the fatigue strength, the results for the weaving technique agree with the existing fatigue class. As expected, the reaction forces showed an appreciable influence on the fatigue strength, which is considered by increasing the stress ratio R. Welding by the string-bead technique also leads to the usual fatigue class when based on the nominal stress approach. However it leads to a relatively low fatigue class when assessed with local approaches. This is due to the unexpected crack initiation at the weld root where decreased stresses occur due to downwards oriented angular distortion. Material effects or effects of the local weld geometry as well as unfavourable residual stresses may cause root cracks. The measurements of the transversal reaction force showed high shrinkage forces. In a continuative welding simulation for both welding techniques is presented and shows that the residual strains in the root are different for the various specimens. Welding with the weaving technique leads to compressive strains, while the string-bead technique leads to tensile strains that may be responsible for the bad fatigue results of this technique. Generally, the fatigue investigations indicate a clear influence of the welding technique on the fatigue strength of a weld.
Strength of block joints welded with large gaps
Welding and Cutting ; 10 , 2 ; 111-117
2011
7 Seiten, 13 Bilder, 3 Tabellen, 8 Quellen
Article (Journal)
English
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