10/03/2016 — auf Deutsch lesen

Long-term monitoring of wind rotor blades

Photo: IVC

Photo: IVC

 
Rotor blade with integrated sensors in testing equipment Photo: TITK

Rotor blade with integrated sensors in testing equipment Photo: TITK

 
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Two successfully completed projects in Dresden and Rudolstadt are paving the way for the application of textile sensor technology in wind rotors. Following the apparel, medical engineering, architecture and automotive sectors, intelligent or smart textiles are now making inroads in the energy sector.

Rotor blades generally consist of glass-fibre reinforced plastic or, in the case of high loads and particularly great lengths (75 metres in the offshore sector) of carbon-fibre reinforced plastic. The Institute for Textile Machinery and High-Performance Material Technology (ITM) at the Technical University of Dresden has come up with a pioneering development for the energy sector namely, the continuous sensor monitoring of the rotors on wind turbines.

To effect continuous monitoring of these often inaccessible fibre composite blades, the researchers exploit the so-called piezo-resistive effect of carbon filaments: The material which until now has chiefly been used for reinforcement purposes, changes its electrical resistance in response to stresses, such as tensile stress, bending or torsion. Deformations or even fissures resulting from fatigue or wear and tear, that threaten the functionality of the blades, can be securely registered and localised using integrated sensors.

At the same time, the project developed a technology to enable the automated, comprehensive integration of textile elongation sensors and sensor networks in the multi-axial materials used as standard in the construction of rotor blades from fibre composites. In doing so, the scientists employ a specially developed module to change the course of the warp yarn in a conventional Malimo warp knitting machine. “The machine incorporates two-dimensional carbon sensor structures into the multi-axially reinforced structure at almost any angle,” states Dr. Andreas Nocke, Research Group Head of Measurement and Sensor Systems at the ITM.

This is paving the way for the mass production of function-integrated, semi-finished textile reinforcement parts for lightweight components with continuous structural monitoring over the entire product life cycle. This, in turn, will lead to lower operating and component checking costs, early recognition of defects, and also optimised component design. Besides a rotor blade demonstrator, the project also produced a product sample of textile reinforced membrane structures with integrated sensor networks.

Operating as energy converters, piezo sensors from the Thuringian Institute for Textile and Plastics Research (TITK) in Rudolstadt generate the electricity required for the sensor system.