# Comparative Study on Vibration Characteristics of Biaxial Carbon/Glass Hybrid Wind Turbine Blades
## 1 Introduction  
The vibration forms of wind turbine blades are mainly divided into swing, oscillation, and torsion. Vibration refers to the deformation or movement of blades under the action of the flow field, which in turn affects the flow field in the opposite direction, resulting in changes in the load size and distribution position of wind turbine blades [1, 2]. Strong vibration of blades is often the root cause of accidents. When the pulse frequency approaches the natural vibration frequency of the blades resonance occurs, leading to cracks in the wind turbine blades and the occurrence of accidents [3]. Therefore, improving the vibration resistance performance of wind turbine blades is of great significance for improving the safety and reliability of blade materials for wind turbine operation [4]. Carbon/glass hybrid fiber material, as one of the new materials, has a lower cost compared to carbon fiber and can exhibit significant hybrid effects, resulting in better comprehensive benefits [5]. [PERSON] et al. [6, 7] studied the tensile properties of biaxial warp knitted and three-dimensional woven composites, and the results showed that the tensile strength of biaxial warp knitted composites in a certain direction is slightly higher than that of three-dimensional woven composites. [PERSON] et al. [8] prepared material samples by changing the volume ratio of carbon to glass, and conducted tensile and compressive tests. The results showed that the compressive strength of carbon fiber/glass HFRP specimens was on average higher than that of specimens with dispersed glass fiber distribution. [PERSON] et al. [9] selected a sample with a carbon glass volume ratio of 1:1 and conducted three different layers. The experiment showed that the 0\({}^{\circ}\) fully aligned structure withrelatively concentrated carbon fibers had the best tensile properties. In addition, numerous researchers have conducted research on the carbon/glass fiber hybrid ratio and layup angle, and prepared various samples, all of which indicate that carbon/glass hybrid fibers have characteristics such as high strength, large elastic modulus, high stiffness, and light weight compared to glass fiber materials [10; 11; 12]. Based on the above, it is feasible to use carbon/glass fiber as a hybrid material as a new type of material for wind turbine blades. However, the new type of carbon/glass hybrid fiber material blades still need to be simulated under various operating conditions and environmental conditions, and the material's stress analysis should be carried out to achieve accurate modeling. In order to further explore the mechanism of blade vibration, scholars [13; 14] studied the natural frequency and natural vibration mode of wind turbine blades, and obtained the changes in blade response and frequency. [PERSON] [15] analyzed the free vibration characteristics of the blades, indicating that the natural frequency of the blades is affected by the ply angle, speed, and taper, with the least impact from the speed and the greatest impact from the ply angle. [PERSON] et al. [16] proposed a new predeformation method to compensate blade deformation based on the load increment method, and analyzed the influence of load conditions on blade predeformation by modifying the stiffness matrix. [PERSON] et al. [17] simplified the wind turbine blades as rotating flexible cantilever beams for dynamic research, and established dynamic differential equations for structural-free vibration based on [PERSON]'s principle. [PERSON] et al. [18] used the finite element fluid structure coupling method to study the influence of wind shear on the vibration characteristics of wind turbine blades with geometric nonlinearity. [PERSON] and [PERSON] [19] used the hypothetical modal method to study the vibration characteristics of pretwisted blades at constant speed under the coupling effects of tension, bending, and torsion. [PERSON] et al.