P 869 – Laser-welded T-Joint Connections – Development of basics and optimization of production and application in shipbuilding and steel bridge construction
Laser welding technology supersedes conventional welding technologies in parts of the steel processing industry. Reasons for this are fine and high quality laser weld seams, that are created at high speed and thereby do cause only a low thermal stress for the jointed components. In addition, the laser stake weld allows for an efficient production of closed structures as steel hollow plates with upper and lower flange and interjacent webs or profiles.
Yet experimentally verified design-methods for laser welded T-joint connections under loadings that typically occur in structural steel work or steel bridges are missing. Laser stake welds are not embedded in current standards like EC 3 nor there are investigations regarding the fatigue resistance of laser welded full depth welds under normal-, shear- or bending stress.
The goal of this research project was to utilize the economic and technical advantages of the laser welding technology in steel construction and shipbuilding industries by providing all necessary scientific and technical knowledge regarding the design and production of laser-welded T-joints. Furthermore, basic capabilities of connecting laser-welded hollow plates for their use in large steel structures should be developed. Additionally, a specification of joints for the fields of application of shipbuilding and steel bridges and their different requirements on load transferring structures were carried out in order to improve significantly the profitability and quality of such steel structures by using laser -welded profiles and hollow plates.
Within the project, welding parameters and minimum manufacturing standards for laser and laser hybrid fulldepth welds and laser stake welds were developed and derived by experimental studies for typical steel construction loads such as normal force, bending and shear on the detail T-joint. Based on these models, the laser-welded semi-finished hollow plate was widely examined in an analytical, numerical and constructive manner with regards to its usage in shipbuilding and steel bridges.
It could be noted that the hollow plates using the improved laser seams are fundamentally suitable both for highly loaded decks in ship structures and also for strongly fatigue-loaded structures such as steel bridges. In addition, initial fatigue tests on joint constructions of the closed structures to load transferring elements were performed. Thereby, promising results have been obtained for application of the elements in practice.
The research project IGF-No. 16935 BG from the Research Association for Steel Application was supported by the Ministry of Economic Affairs and Energy through the German Federation of Industrial Research ssociations (AiF) as part of the programme for promoting industrial cooperative research (IGF) on the basis of a decision by German Bundestag. The research project has been carried out at Fakultät Bauwesen, Fachgebiet Stahlbau, Technischen Universität Dortmund, at Institut für Konstruktion und Festigkeit von Schiffen, Technische Universität Hamburg-Harburg and at Schweißtechnischen Lehr- und Versuchsanstalt Mecklenburg- Vorpommern GmbH, Rostock.
Only available in german language.
D. Ungermann, C. Rüsse, W. Fricke, C. Robert, R. Peters, A. Sumpf