Evaluation of the fatigue resistance of butt welded joints in towers of wind turbines - experimental setup
Source: BAM
Wind turbines must endure a high number of load cycles during their service lifetime. Therefore, the fatigue strength verification plays an important role. Butt-welded joints are one of the most common structural details in the tower structure of wind turbines. In general, the nominal stress method is used for their fatigue verification. The Eurocode 3 part 1–9 is the current design standard for this field of application and defines the fatigue resistance by pre-defined FAT-classes. This paper presents recent results of fatigue tests on small-scaled specimens and large components with transverse butt welds to discuss the validity of the FAT-class. In addition, results from numerical simulations for the verification with the effective notch stress and the crack propagation approach are used for comparison. For this purpose, macroscopic measurements of the weld seam geometry and a 3D scan were used for a realistic consideration of the notch effect in the simulation. Based on the consistency between the numerical results and the fatigue tests, the influence of the seam geometry on the fatigue resistance was worked out. Furthermore, a prediction of the fatigue strength of butt-welded joints with plate thicknesses up to 80 mm was carried out.
Evaluation of the fatigue resistance of butt welded joints in towers of wind turbines - a comparison of experimental studies with small scale and component tests as well as numerical based approaches with local concepts
Ralf Glienke, Florian Kalkowsky, Adolf F. Hobbacher, Alexander Holch, Marc Thiele, Frithjof Marten, R. Kersten, Knuth-Micheal Henkel
published in Welding in the World (2024), pages 1 - 26