Beam finite element for wind turbine blade based on geometrically exact beam theory

With the development of the wind energy, wind turbine blades are getting larger and more flexible, which makes the nonlinear dynamic behavior of wind turbine unfold more clear. Nonlinear effect is a relatively new focus area in the wind turbine territory. In order to study nonlinear performance caused by large deformation, the nonlinear unit of blade was built based on geometrically exact beam theory. The effect of nonlinear material and eccentric cross-section on the blade unit was considered. The integration equation of motion was discretized by using Gauss- Lobatto quadrature formula and differential quadrature method, and incremental linear equation was derived. The correctness of unit was verified by three standard examples. Further, the blade unit was used as the blade of 10 MW wind turbine and mode analysis. The natural frequency and vibration shape of wind turbine system was obtained correctly.