Stiffness of a Foldable Tower for Wind Turbine

Zheng Cai, Hui-Chan Zhao, Jing-Shan Zhao*, Fu-Lei Chu
Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, P. R. China

© 2012 Cai et al

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: ( This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, P. R. China; Tel: 86-10-62788308; Fax: 86-10-62788308; E-mail:


With the shortage of fuel in the world, wind power becomes one of the most potential energy today. For the demand for more energy from wind turbine, the tower is tending to be designed much higher than before to capture the wind with faster speed. However, the higher the tower is the more possible the catastrophe of a whole wind turbine structure will occur when hurricanes come. This paper proposes a foldable tower for wind turbine to avoid the disasters brought about by strong wind in the high-level sky. The tower can be folded when hurricanes come and can be deployed fully to acquire more wind power in high sky in the normal cases. Firstly, the geometry design of a deployable structure is presented in details by discussing the deployable ratio. Then, it focuses on the statics, stiffness analysis of this structure. The equivalent stiffness of the foldable tower is expressed as a function of the primary design parameters and the deployable angle. What must be pointed out is that the result comprehensively expresses the dependence of the stiffness on the deployable angle and the stiffness of the fully deployed case. This is particularly useful for the applications in wind turbine.

Keywords: Foldable tower, geometry design, statics, stiffness analysis.