Integrity requirements of a wind turbine tower

Abstract

Most large wind turbines currently installed use self-supporting steel tubular towers. The present study aims to per- form a structural analysis of a 100 kW wind turbine tower, taking into consideration several structural integrity requirement s. Among many requirements of the design of a tower, the analysis of free vibration has been performed. Details of static and elas- tic stability analysis are also presented. The integrity analysis was performed using the commercial software ANSYS. The height of the tower was defined as 24 m. The tower has been designed as an assembly of four 6 m height modules connected by bolted joints. A special consideration of the module connections will be presented. Flanges are adopted to strengthen the tower modules end, having also the purpose of attaching the modules extremities by pre stressed bolts. Contact elements were adopted for the joint model. A distinct tool provided by ANSYS is the possibility of applying a preload to the connecting bolts. Under the condi- tion of a load produced by the turbine blades thrust, the connected flanges tend to separate at the outer edge. One may obtain the state of deformation of the opened joint. Results of the stress analysis of the joints reveal a major stress concentration at the base of the bolts heads.