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18. A Novel Structural Analysis of Composite Wind Turbine Blades



Annual wind power generation capacity in the US has increased from 3 gigawatts in 2000 to 61 gigawatts in 2013 and is on track to fulfill 20% of projected U.S. electricity needs (305 gigawatts) by 2030. To enable the increase in electricity generation of wind turbines, longer blades are being designed which require improved engineered blades to handle higher loads. Thus, the wind turbine industry is turning to the use of carbon-epoxy composite materials to take advantage of their low weight yet high strength ratio and improved fatigue resistance. Current analyses to design turbine blades utilize either Finite Element Analysis programs, which are time consuming and costly for conducting parametric studies in the preliminary design stage, or use analytical solutions which are inaccurate or too complex. In this research, an analytical model based on a modified classical lamination theory will be made and coded into MATLAB to quickly conduct a structural analysis on portions of composite turbine blades with airfoil cross. The current model takes into consideration composite ply variation along the contour of various airfoil cross-sections. This analysis will predict the structural stiffnesses and stresses and strains in individual composite plies of Ibeam stiffened airfoil blades under axial, bending and torsional loads. Results will be validated using ANSYS FEM. Stiffeners will also be analyzed separately from the blade structure to understand their stiffness characteristics. Thus, by enabling a quick and simple, yet accurate static analysis on composite turbine blades, improved initial designs can be determined in an early design phase to allow more efficient, reliable, and economical turbine blades to be made.

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