Research On The Bearing Capacity Analysis And Optimization Of Large Inner Stiffened Wind Turbine Tower

The tower load is very complicated as the main supporting structure of the wind turbine in the complex natural environment.In addition to bearing the aerodynamic load acting on the wall and weight of the tower,it also bears the gravity,thrust and yaw moment by the wind wheel and nacelle.Its mechanical properties directly affect the performance of wind turbines.This paper mainly uses the finite element method and the Isight optimization software to analyze the stability and optimization of the wind turbine tower.Wind turbine is mainly composed of blades,nacelle and tower,and each of them have a big difference in material,design and manufacture.In order to meet the stiffness,strength and stability requirements,the tower load needs to be calculated firstly.This paper analyzes the features of the tower loads,and uses GH-Bladed software,simplified formulas and Japan code to calculate the load of wind turbine tower.It provides reference for the structural design of tower.The model of wind turbine tower is established in using the finite element software Abaqus and python language.The modal analysis,linear and nonlinear buckling analysis are performed in Abaqus.The stability of the wind turbine tower under multi loads is checked according to the ENV1993-1-6 and DIN18800-4 standards.It determines the ultimate buckling load of the tower,which provides the gist for improvement and strengthening of the tower.The stiffening shell structure has higher flexural stiffness and buckling bearing capacity.So it is effective to improve the bearing capacity by increasing stiffening ribs on the inner wall of the tower.The stability of the conventional tower and stiffening tower are researched and compared taking into account the initial geometric imperfection effect.The research shows that the stiffening rib can improve the ultimate buckling load of the tower,and the initial imperfection can also be considered.The stiffening rib restricts the local buckling of tower,changes the failure mode of the tower,and improves the ductility and bearing capacity of tower.The tower parameters such as diameter,thickness of each section,the size and layout of the stiffening rib directly affect the cost and safety of the whole tower.Based on the Isight software,this paper uses the NSGA-II algorithm to optimize the thickness of tower,the size and numbers of the stiffening ribs on the basis of stability.The optimization results show that the quality of the tower is reduced,the thickness of tower decreases,the maximum displacement and stress increases.It shows that the material is fully utilized after meeting the requirements of constraint and stability.