New solutions for wind turbine towers

Ruukki wind tower Ruukki is partner in a European project, High Strength Steel Tower for Wind Turbines (HISTWIN), to develop a new, more economical solution to join parts of wind turbine towers. In addition, the project is also tasked with improving the fatigue performance of steels used in wind turbine towers. Invited guests heard about the progress made with the on-going project at the premises of German certification body GL Wind in Hamburg.

The project aims to develop a new method to join the parts of a wind turbine tower together without flanges and to prepare a design guideline and cost analysis by June 2009.

”Machined ring flange connections have traditionally been used to join the parts. The method under development is both more cost-effective and faster,” says Research Manager Juha Nuutinen from Ruukki.

In the connection method under development, friction types of joint, TCB bolts, are used to join the parts to each other. No welding is required and the properties of high-strength steel can be utilised in the structure.

”Initial tests of the joint properties and performance have now been carried out in the laboratory. The results to date have been promising. The new joint enables higher stresses in the tower shell, which in turn means looking to special steels to improve the fatigue performance of wind turbine tower structures. Field measurements are the next step,” Nuutinen explains.

The three-year research project, managed by Luleå University of Technology in Sweden and funded by the European Research Fund for Coal and Steel (RFCS), represents a broad spectrum of European wind power expertise. Other partners in the project are universities, tower designers, turbine manufacturers and a certification body. Ruukki was invited to join the project as a materials expert.

Managed by the European Commission, RFCS funds research projects in the coal and steel sector. There are plans to continue the research project to develop even higher wind turbine towers.