Functional and safety components of thermoplastic composites are being used more and more. It is therefore very important to have an understanding of the material behaviour and to develop adapted design methods.
To ensure their suitability when used in wind energy systems, the epoxy resin adhesives used must be suitably certified by Germanischer Lloyd (GL). This is because rotor blades must withstand extreme stresses. The larger the unit, the higher the demands on the fatigue strength of the rotor blades manufactured from composites. In the near future, experts predict 10 megawatt systems with 80 metre long wind vanes.
The enormous rotor blades consist of two half shells, that are produced in suitable moulds from cross-linked hard foams and inserted balsa woods, which are subsequently stuck together. The balsa wood is cultivated in plantations in Ecuador and is harvested after six years. From a one metre long tree trunk, rectangular timber sections are cut and stuck together to make 1.22 metre long and five centimetre wide ashlars. These blocks are then cut into boards against the grain and finely sprayed with a resin solution to protect them against moisture.
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