Investigation on torsional performance of wind turbine blades under pure torsion through subcomponent test

Abstract

Torsional performance has received little attention in the process of blade design. Furthermore, the mechanical response of main structural components is unknown under pure torsion. This paper studies the torsional performance of the blade segment through the latest subcomponent test method. The blade segment, which length is 5m, is cut off from the blade in service. The subcomponent test rig is designed specifically to apply pure torsion force to a blade segment. The structure response of the blade segment under pure torque is recorded through a preset data acquisition system. This study also used the finite element model established with combined shell/solid mesh to predict the test. Finally, it is compared with the test results, and the two have achieved a good agreement. It is found that the blade segments show apparent nonlinear behavior after being subjected to pure torsional force, including inclination response, stress response, and strain response. The inclination angle increases faster in the early stage and slower in the later stage with the addition of load. The maximum stress region is the sandwich and adhesive joint. Moreover, the stress of specimen near the fixed side is higher. The strain results show that the pure torsional force on the specimen is transformed into a positive and negative strain of the sandwich and adhesive joint. Both ends of the specimen are the dangerous region of it. These novel conclusions provide a valuable reference for the design of the blade.