Preliminary design procedure for large wind turbine blades based on the classical lamination theory

Designing the structure of a wind turbine blade is a nontrivial task. Nowadays, finite element software is widely applied for its design and computation. However, huge computational resources and time are required for modeling and evaluation of large composite turbine blades. Additionally, a significant amount of design parameters is required to be handled; thereby, it is difficult to perform a systematic parametric study. This paper presents a preliminary procedure for the initial structural design of a large wind turbine blade based on the classical lamination theory (CLT). By analyzing the existing blade, the optimized numbers of the spar cap layers in the blades are estimated. Furthermore, a parametric study using the carbon fiber-reinforced plastics (GFRP) and glass fiber-reinforced plastic (CFRP) at multiple fiber orientation angles for the spar cap design is attempted with respect to the axial and twist coupling stiffness coefficients for each material design. Based on the constitutive equation, an analytical design approach of a laminated composite blade is developed and compared with a three-dimensional finite element blade model. The results show good agreement; thus, the design procedure provides a foundation for the initial structural design of a wind turbine blade.