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Cyclic Loading of a Suction Bucket Using a Pre-Owned Materials Testing Machine

The Leibniz University of Hannover, with its broad range of disciplines is one of the leading universities in Germany. At the university’s Institute of Geotechnical Engineering, research is currently being conducted on suction buckets for offshore wind turbinesusing a pre-owned Z050 testing machine from ZwickRoell, with some very interesting modifications.

Suction buckets

Offshore wind turbines are typically built on pile foundations, which are driven into the seabed when installed. Under certain conditions, so called suction buckets, which provide ecological benefits as well as cost savings, can be used an alternative. Harmful effects of sound on marine animals, birds, fish and the community of organisms living on the bottom of the sea (benthos) can be reduced through the use of suction buckets. Suction buckets are steel cylinders with an open bottom, which are placed on the seabed and suctioned into the ground by creating negative pressure. The name bucket comes from the fact that these cylinders resemble an upside down bucket. Installations of bucket foundations are quiet, fast and cost efficient, and can be removed in an environmentally friendly manner after their service life expires.

Special solution for the simulation

For simulation of the cyclic load caused by wind, waves and operation of the suction buckets, the pre-owned Z050 testing machine was turned upside down and the top crosshead was laid out for torsion operation. For the test, a true to scale suction bucket is suctioned into an underwater sand bed with the testing machine, in a force-controlled manner.A cyclic load is then applied to the suction bucket.

Insights into the Poject ProBucket and additional information on bucket foundation systems can be found on the Hannover Institute of Geotechnical Engineering website: www.igth.uni-hannover.de.

Benefits such as testing with state-of-the-art technology, innovative testing software, investment security of the system and a contribution to sustainability convinced the Leibniz University Hannover to collaborate with ZwickRoell on this project, to use a pre-owned testing machine, and to execute this interesting machine layout.

In collaboration with our customers, ZwickRoell will gladly take new approaches for the environment—even if that means turning things upside down.

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