Finite Element Analysis of a Composite VAWT Blade

Abstract

High values of centrifugal forces play a significant role in the design of straight blades of a vertical axis wind turbine. Centrifugal forces add up with aerodynamic forces and result into a high value of bending stresses and deflections in these blades. These forces can be reduced by reducing the weight of the blade which can be done by choosing a low density material. The blade made up of composite materials can have thin walls due to high strength to weight ratio of the materials. A straight Darrieus vertical axis wind turbine blade made up of Aluminium was designed in the previous research. The same blade is modeled with a composite material to optimize its design. It is discussed why Glass-Epoxy can be chosen as a suitable composite material to model a wind turbine blade. SOLID and SHELL element types are analyzed and layered SHELL elements are found as more useful to model the composite blade. Different stacking sequence and ply thickness of Glass-Epoxy is used and a right stacking sequence is found. The values of all forces acting on the blade are computed and compared with the Aluminium blade. The unidirectional strength is achieved by computing and optimizing the results of maximum deflection and maximum stresses at the location where maximum loads are applied. High strength to weight ratio is achieved by reducing the values of centrifugal forces, maximum deflections and maximum stresses in the composite blade.