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978-3-8439-2524-2, Reihe Ingenieurwissenschaften
Matrix dominated effects of defects on the mechanical properties of wind turbine blades (LCC Band 15)
176 Seiten, Dissertation Technische Universität München (2015), Softcover, A5
Nowadays, wind energy rotor blades exceed the length of 70 meters. Composite materials offer enormous savings compared to metallic material due to lower weight and excellent mechanical properties. The manufacturing of wind turbine blades is subjected to extraordinary demands for low costs of production. It is not extraordinary that both, structural penalties in the selection of material are made, and fabrication inaccuracies are tolerated to keep production costs low.
After studying the influence of the matrix system on the global structure, the matrix dominated effects on a local level taking fabrication effects such as ply waviness are reviewed. Ply waviness poses a commonly occurring fabrication defect of rotor blades at which the strength behavior of the composite is essentially influenced by the matrix systems and their properties. The present work engages in a phenomenological understanding of the structural mechanical influence of ply waviness with a particular emphasis on the effects of matrix systems. The behavior of stiffness and strength parameters are determined analytically and numerically. Numerical simulations validated by experiments show that the failure mechanisms for compression and tensile loads are both driven by the matrix properties.
The outcomes presented here provide a valuable exposure to the development of matrix systems that are damage tolerant to common fabrication defects. The trade-off between a cost-efficient material selection and sufficient structural properties tenders an individual infusion of the subcomponents spar caps and the aerodynamic shells using two different matrix systems that are adapted to the structural and manufacturing needs.