The Aluminum Ring (Aluring) fatigue cracks is one of the most severe problems found in wind turbine blades from 500-750kW. These cracks are generated on the threaded holes buttons as well as in the threads. The sum of different cracks can lead to a blade root breakage causing production loose and producing high risks to the wind turbine and the wind farm.
We introduce a T-Bolt connection between the blade and the hub, replacing the conflictive original blind threaded hole connection. There is no need to exchange the aluring because the new T-Bolt connection compresses any existing crack and reinforces the blade-to-hub connection.
This new repair solution is validated by different prestigious Engineering firms confirming the validity of the solution as well as the reliability improvement of this new connection.
One rotor is repaired in one day using Regenblade’s drilling tool made with 6 drills working at the same time. Due to its simplicity, there is no transportation cost. The drilling tool and materials are easily shipped to the site where the blades are located.
There are huge cost savings (up to 60%) compared to other repairs since there is no transportation costs, no more aluminum ring monitoring needed, etc. But one of the most important features is that the T-Bolt repair is a forever solution.
SGS, a Swiss based company, ranked as the largest Certification entity of the world, has Certified our T-bolt solution with 21 mm diameter barrels against IEC 61400 for G47 and V47 wind turbines. This worldwide standard is the mandatory one to design wind turbine generators and rotor blades.
By fulfilling this IEC standard, Regenblade solution is Certified to last at least 20 years in the worst wind Class conditions.
Solution has been tested with a one bolt specimen under the calculated loads seen after the complete FEM analysis. The test results are showing a perfect correlation with the ones predicted through the theoretical fatigue calculations, validating therefore the FEM and theoretical fatigue calculations. Tests successfully overcame the 10 million cycles for the wind turbine loads of its wind class.