# Comparative Study on Vibration Characteristics of Biaxial Carbon/Glass Hybrid Wind Turbine Blades
## 6 Conclusions  
Laminated plates and blade reinforcements have similar structures. In this paper, a new type of carbon/glass fiber hybrid material is used as the blade reinforcement. Different carbon glass hybrid materials are selected and laminated plates are prepared using an epoxy resin matrix. Based on the material constitutive equation and modal analysis theory, the tensile properties of the materials are analyzed, and a 10 kW NACA0012 blade model is established. Three types of blade vibration modes, displacement changes, and stress  
Figure 20: Blade Stress Distribution Diagram. (**a**) Three dimensional diagram of blade stress distribution. (**b**) Blade stress changes over time. (**c**) Blade stress changes with spanwise direction.  
distributions with a carbon/glass fiber hybrid ratio of 2:6, 4:4, and 6:2 are discussed. The following conclusions are drawn:  
1. Under the same process and layer angle, the tensile performance of blades with a carbon/glass hybrid ratio of 4:4 was significantly improved compared to 2:6. Subsequently, as the carbon content of the sample increased the improvement in blade performance became smaller. Therefore, it is estimated that the maximum improvement in tensile performance was achieved between 6:2 and 4:4 for the blades.
2. As the wind speed in the flow field increases the maximum deformation of the blade gradually increases, and the improvement in deformation resistance of blade A1 to blade A2 is most significant. From the velocity deformation fitting curve, compared to blade A1, the deformation trend of A2 and A3 blades is more stable, and the overall deformation resistance is better.
3. From modal analysis and the maximum displacement curve under rated wind speed, it can be seen that the displacement changes in all three directions of the blades tend to converge, and the vibration frequency is greater than its corresponding first-order fixed frequency and less than its second-order fixed frequency, without resonance phenomenon. The main vibration form of the blades is waving. Blade A2 and blade A3 reach equilibrium after 3 s, while A1 takes 5 s to reach equilibrium.
4. From the stress distribution diagram, it can be seen that the concentrated force on the blade is at 1/3 of the position and exhibits periodic changes. This change may lead to the deformation of the blade, causing changes in the flow field structure near the blade and the phenomenon of blade waving.  
Conceptualization, X.J. and Y.J.; Methodology, X.J. and X.G.; Software, Y.J. and K.Z.; Validation, Y.J., M.G. and J.S.; Formal analysis, L.F. and S.W.; Investigation, J.S.; Resources, X.J. and Y.J.; Data curation, X.J. and Y.J.; Writing--original draft, Y.J.; Writing--review & editing, Y.J.; Supervision, X.J.; Project administration, X.J. and X.G.; Funding acquisition, X.J. and X.G. All authors have read and agreed to the published version of the manuscript.  
The research of this project has won the general project of the National Natural Science Foundation of China (approval number: 12272189), Supported By Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region (approval number: NJYT23022), the Research Science Institute of colleges and universities in Inner Mongolia--key project (approval number: NJZZ2395), the basic research business fund project of colleges and universities directly under the Inner Mongolia (approval number: JY20220119), and the Research Science Institute of Inner Mongolia University of Technology--doctoral fund (approval number: BS2021056).  
All authors have read and agree to the published version of the manuscript.  
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The authors declare no conflict of interest.