Nabrawind and Naitec develop a comprehensive intelligent blade root repair solution

Both entities collaborate on a project for the development of a blade root repair method that also allows monitoring of the joint by integrating sensors into the repaired area.

The Navarra-based company Nabrawind and the technological center Naitec have developed a project that enables the repair of blade roots, damaged during operation, with integrated sensors. This way, it is possible to restore the original strength of the blade and extend its lifespan. This project is part of the “Grants for R&D Projects 2022,” driven by the European Regional Development Fund through the 2021-2027 Navarra Operational Program.
 
Blade failure during operation represents a significant percentage of reasons for unexpected stoppages in wind farms, reducing their productivity. Specifically, defects that propagate in the blade roots due to the loads applied to the joints are common in the wind market, leading to significant repair and/or blade replacement costs, for which there is currently no economically viable and reliable solution.

As a result, developing a more environmentally friendly and cost-effective solution than blade replacement, and more reliable than current repair options, is considered essential to extend the lifespan of affected turbines. Therefore, Nabrawind and Naitec have designed a solution that, on one hand, allows the repair of the blade root, avoiding the need to replace the entire component, and on the other hand, overcomes the uncertainty and lack of reliability that follows a failure, thanks to the non-intrusive integration of printed sensors.

In this way, the two Navarra-based entities have undertaken this new project, called the Development of an Integrated Intelligent Blade Root Repair Solution for Wind Turbines [RootFix].

Specifically, the repair process removes the damaged section with a radial cut and allows the inspection of damage propagation in the internal area of the blade, with the aim of restoring the structure of the component and then carrying out its reconstruction. To do this, a prefabricated laminate is used that attaches to the repaired surface and also incorporates new connection elements (T-Bolt) that connect a cylindrical metal extension piece (which compensates for the cut blade section) located between the blade and the hub. This prefabricated element also incorporates printed sensors that monitor the joint and its effect on the blade structure, minimizing its intrusiveness in the structure, and maximizing data collection to know its operational status at all times.

In this context, the project by these Navarra-based entities has focused on achieving six key strategic objectives that will contribute to strengthening the wind sector both locally and internationally:

1.  Zero-defect fastening: Achieved through a metal piece that connects the blade’s T-Bolts with the hub’s bolts, avoiding defects that may arise with bonded joints processed outside the plant.
2.  Adaptability: The reconstruction process adapts to any blade design and size through a validated methodology for damage assessment, insert dimensioning, and bolt joint optimization, minimizing aerodynamic impact.
3. Structural reliability: Ensured with advanced joint sensorization to monitor the blade structure during its lifecycle, exploring various sensorization techniques.
4. Reduction of time and resources: The repair and installation of damaged blades are optimized, reducing the time to 5 days, representing a significant improvement over current methods, while also eliminating the dependence on expensive and low-availability cranes when combined with BladeRunner.
5. Cost reduction: Achieving up to 75% reduction in costs compared to blade replacement, avoiding expenses associated with the manufacturing, transportation, and installation of a new blade, especially with the increasing blade sizes.
6. Reduction of environmental impact: Promoting the circular economy by extending the life of the damaged blade, preventing waste and CO2 emissions from recycling.

The phased structuring of the project has allowed these objectives to be met sequentially, successfully completing the different phases of design, sensor integration, testing, and manufacturing trials.