Structural Analysis And Experimental Study On The Behavior Of A Prestressed Prefabricated Sectional Wind Turbine Blade Using T-bolts

Due to the shortage in traditional energy and environmental pollution problems, as a kind of clean and renewable energy, wind energy has been paid more and more attention. In recent years, the development of new wind energy in China has been ranked first in the world. Along with the gradually growth in wind turbine capacity, the length of wind turbine blade increases accordingly. In China, the widely used MW-level wind turbine blade is generally more than 40 meters long. The V112-3.0 MW wind turbine blade produced by Vestas has a length 55 meters. The increasing length of wind turbine blade brings difficulties and challenges in transportation. In order to explore the wind energy in the fourth wind zone with an annual wind speed approximately 6.0 m/s at mountain areas, long wind turbine blades should be employed to improve the wind-catching capacity. It is difficult, risky and expensive to move the long wind turbine blades to the top of the mountain. Dividing a traditional blade into several prefabricated segments and assembling them on-site is an efficient solution to overcome those possible problems. In this study, a new prestressed prefabricated sectional wind turbine blade by connecting the sectional blades with prestressed high-strength bolts is proposed. After introducing the design concept of the wind turbine structure, numerical study on a full scale mode structure, experimental study on a connection unit and numerical simulation are carried out.This study consists of the following contents:(1) The structure selection of the proposd prestressed prefabricated sectional wind turbine blade by the use of T-bolt connection is introduced.(2) A full-scale joint segment of the proposed prefabricated sectional wind turbine blade was modeled with ABAQUS. The stress distribution of the joint segment is analyzed under the actual load of the blade. Results show that load-carrying capacity of the proposed prefabricated sectional wind turbine blade using T-bolts meet the requirement and the applying of prestress on the T-bolts can make sure the glass fiber in compressive to avoid the crack at the connection.(3) In order to test the behavior of the proposed structure, a scale connection unit specimen including one prestressed bolt was designed and fabricated. The tensile test on the specimen was carried out and the stress distribution was measured. Test results show the connection unit will be safe under the design loading levels and the scheme of the prefabricated sectional wind turbine blade is feasible.(4) The connection unit of the proposed prestressed prefabricated sectional wind turbine blade was modeled with ABAQUS and numerical simulation was carried out. Comparing between the numerical simulation results and the tensile test of the connection unit under the same loading conditions were carried out and results show they agree well with each other.