With the expansion of renewable energies, the number of offshore wind turbines is also steadily increasing worldwide. Due to harsh weather conditions, maintenance and repair work on the high seas is much more difficult. This causes considerably higher operating and maintenance costs than comparable wind farms on land.
The more difficult conditions on the high seas only allow a limited detection of damage with conventional testing techniques. Since enormous forces such as the dead weight of the wind turbine, the flow of the water or the force of the waves in conjunction with dynamic loads act on the foundation structure during operation of the turbine, damage such as cracks in welded seams can occur. In order to detect these, the Fraunhofer IKTS has developed a sensor sleeve especially for the offshore sector. The sensors are arranged in a ring around the loaded areas and adapted to the specific requirements, e.g. high seawater resistance. Electronics and sensors are protected by various barrier layers that permanently prevent seawater from entering. The data evaluation is imaged by a Fresnel zone migration. Recorded environmental data are used to correct the measurement signals.