| Abstract: |
In accordance with the objectives set by the Federal Government for establishing a sustainable energy supply it has been planned to develop offshore wind power plants with a cumulated power of more than 30.000 MW till the year 2030. The foundation and bearing structures of the offshore wind power plants are subject to high static, dynamic and cyclic load and are, therefore, built with very thick walls (>>50mm). So far, mainly SA welding has been used for the production of the foundation structures. With regard to the production, however, this welding method entails different disadvantages, such as a high energy input, time-consuming multiple-layer technique, complex weld preparation and also a high consumption of welding filler material. An economically feasible alternative is electron beam welding (EBW). EBW allows the faster and reproducible production of large structures with a higher quality. In mass production, electron beam welding is less expensive than conventional welding since complex weld preparations are not required and, as a rule, filler material is also not necessary. First examinations made with plates with a thickness of up to 100 mm showed, however, that the demands made to ductility and to maximum permissible hardness have not been met. It is the aim of this research project to qualify the EB welding methods as a particularly fast and economically feasible welding method for the joining of steels with a high thickness for the construction of offshore wind power parks. To this end, the improvement of the stress/load bearing capacity of the EB weld shall be examined via a systematic investigation of the influence of different parameters, inclusive the influence of the base materials which are to be joined. In addition, the 27J condition shall be replaced by a modern quantitative ductility requirement which is based upon fracture and damage mechanical approaches.
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