A Study on the Structural Characteristics of the Blades of Wind Turbines under Static Load Condition

Abstract

The study of the structural strength and stiffness of wind turbine blades is an important foundation and guarantee for analyzing the stability and reliability of the complete wind turbine. By analyzing the results of static load experiments and finite element calculation, the stress, strain and deflection of blades can be more precisely determined so as to assess the structural characteristics of blades. We conducted static load tests on the medium-size experimental blades developed by the Institute of Engineering Thermophysics, Chinese Academy of Sciences, and obtained the deflection conditions of flap-wise and edgewise bendings, as well as the analytic results on the strain of the main beams and trailing edges. Meanwhile, a finite element model of blades was built using ANSYS to analyze the maximum deformation, stress, and strain. The corresponding results were compared with those of static load experiments. Then the strain and bending properties of blades under the static load were investigated, and the characteristics of the safety application of blades were verified. The results show that: 1)Within the range of 100% design load, the deflection of edgewise and flapwise directions presented a linear relationship with the applied loads. 2) After the loads in the flapwise direction exceeded 100% design load, a non-linear relationship between the blade bending and the applied loads were found. 3)The blade beam and trailing edge retain good stiffness properties under big strain conditions, and the maximum deformation appeared at the maximum chord length of the trailing edge of the blades. Our results on the static load experiments were basically consistent with the finite element model simulation, which verified the accuracy of the results of the static load experiment and finite element simulation of blades.