Approach and results

The implementation of this research project’s results happens by collaboration of the involved companies and organizations, as well as research reports, publications and lectures.

By collaboration and comparison of different solutions, the selection of the particular requirements to the best suited type of construction is simplified in technical and economical matters. So the costs for building those structures can be optimized and lowered respectively and higher performances can be reached. A significant issue is the adaption and evaluation of the existing fatigue calculation concept to the requirements of O-WEA. The central node was identified decisive in fatigue calculation. In close collaboration with experienced constructors, a innovative alternative with an inner stiffening ring could be designed. This has a better fatigue resistance compared to the conventional design. Further, first pilot tests were made with small samples, which were fabricated in dependence on node sections. Here, different weld seam methods and wall thicknesses are examined and high strength steels are used. In addition, existing design concepts for determination of fatigue resistance regarding the applicability to the innovative Tripod-node are checked. With help from finite elements calculations, crucial pints will be reckoned in detail.

Because the fatigue resistance of critical groove details can be significantly enhanced by the use of adequate post weld treatment methods, the methods of Peening, Ultrasonic Peening (UP) and Ultrasonic Impact Treatment (UIT) were examined closer.

Hitherto existing knowledge about corrosion protection from the oil- and gas industry depend on very complex protection systems, which are not really applicable in the wind energy section due to the lower margins. Comprehensive needs for research exist for this area.