Nonlinear Analysis of Wind Turbine Blades Using Finite Elements with Anisotropic Variable Kinematics

Analysis of wind turbine blades using beam or shell models presents difficulties in accurately capturing the torsional stiffness and local 3D stress fields. Instead, modeling torsional effects accurately often necessitates three-dimensional analysis as achieved with solid elements in finite element analysis. The use of solid elements and complex local mesh refinement algorithms are often required to capture the three-dimensional stress fields in critical regions, which results in systems with a large number of degrees of freedom. The present work proposes using variable kinematics finite elements to analyze wind turbine blades. Variable kinematic elements use a higher-order shape function to represent the displacement field in an element, enabling a more refined kinematic description of displacements. Previous works have shown that higher-order elements with variable kinematics can obtain accurate 3D stress fields with fewer degrees of freedom than conventional solid models. Using p-refinement furthermore allows for local refinement without requiring remeshing. By allowing the kinematics to be directional, the accuracy and degrees of freedom can be tailored to be closely related to the structure.