R&D
Inspired by nature Composite joint for offshore jackets
Monopiles and jackets are used for the foundation of bottom fixed offshore wind turbines. The steel welded TKY joints used for the assembly of jackets form a weak spot in the strength and durability of this type of construction. Start-up company Tree Composites has developed a joint made of composites that eliminates this weakness. ALL PHOTOS COURTESY OF TREE COMPOSITES, UNLESS STATED OTHERWISE.
M
axim Segeren is Managing Director and Co-founder of the young company, and we talk with him about their innovative solution. He became involved in the offshore industry during his study at Delft University of Technology (TUD), where he earned his MSc degree in offshore engineering with a focus on offshore wind jackets, and a PhD degree in civil engineering with the slip joint connection for offshore wind turbines. After his PhD, he remained involved with the TUD. “After promoting,” he explains, “I stayed at the university where I became involved in forming consortia between the industry and science aiming at the development of innovations within offshore wind. One of those innovations was a wrapped composite joint that today is referred to as the TC Joint.”
TC Joints versus steel welded joints According to Mr Segeren, a jacket has an excellent weight/rigidity ratio and this is why they are technically the best foundation for offshore wind turbines. “Despite jackets being the better solution, monopiles are dominating the market, even when they are much heavier than jackets”, he states. “One of the reasons for this is the higher price of jackets and the longer production time caused by the complex welding of the multi-membered joints. The weld also causes local stress concentrations that can reduce the fatigue resistance by 10 to 100 times. To guarantee a lifespan of these complex welds of 25
To guarantee a lifespan of jackets of 25 years or longer, the thickness of steel used in TKY joints is increased locally in the order of 300%.
Photo courtesy of Ørsted.
2 6 | O S I 2 0 2 2 | Volum e 15 | Issue 3
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