유한요소 모델을 이용한 풍력발전 블레이드 설계

Abstract

The objective of this work was to design a 750kW wind turbine blade (IEC type class IA) using the finite element method (FEM). Only 3D finite element blade model was used during the whole detailed design procedure. The blade model is 24.1m long and consists of glass-epoxy laminate. The blade structure comprises multi-axial sandwich shells with two main UD glass tape spar caps and a UD reinforced trailing edge as well as a tri-axial (3AX) glass fabric in the blade root to transfer loads into the blade connection. 11,160 4-node shell elements and over 5,000 element groups were generated to model the composite blade of various stacking sequence. I-DEAS, commercial FEM code was applied in drawing and meshing, and ABAQUS in analysis. Four extreme cases which cover all design load cases specified in the GL guideline were defined and applied for structural analyses. The static and fatigue load carrying capacity, tip deflections and modal characteristics were evaluated to satisfy the strength and stability requirements. From calculations, it was verified that the designed rotor blade achieved the sufficient static and fatigue safety margins (S.F. or R.S.F > 1.0) in spite of increased natural frequencies. According to the final results of structural design, the prototype of the rotor blade was manufactured by the resin injection molding (RIM) method and passed all full-scale proof tests for certification, natural frequency test and static test. During the tests, any fracture, wrinkle or buckling of the blade did not occur and measurement results were in agreement with FE calculations within deviations of GL guideline. As a result, the design process of wind turbine blade using FEM was confirmed and established as reliable one.