## 1 Introduction  
In order to improve the efficiency of wind power generation, wind turbines are moving towards a large-scale development. While developing them on a large scale, it is also necessary to make them as efficient, safe, and reliable as possible, which makes the safety of wind turbine blades and towers very important. Therefore, it is necessary to investigate the fracture failure and vibration issues of large wind turbine blades and towers. The destructive fracture phenomena of megawatt wind turbine blades and towers that have occurred around the world in recent years also indicate the necessity of studying this issue [1; 2]. In the past decade, the research on wind turbine blade vibration has generally focused on the problem of the stall-induced nonlinear aeroelastic stability of blades (i.e., stall flutter in coupled vibrations under the combined action of structural nonlinearity and aerodynamic nonlinearity [3], linear classical flutters at high wind speeds [4], and fracture failures caused by vibrations from various turbulence and wake effects [5]. From the perspective of wind fields, some scientific research institutes have established systematic methods for the ultimate structural failure of wind turbines under extreme wind conditions through the three-dimensional (3D) computational fluid dynamics (CFD) simulation of complex wind field characteristics and the aeroelastic coupling analysis of turbine structures [6]. The wind turbine structure mentioned here not only includes large blade systems, but also includes engine room systems and tower structures. The tube sections of large wind turbine towers are usually made of Q345 steel plates with different thicknesses and rolled into a conical tube structure. Then, several tube sections are welded into \"long sections\", and every two \"sections\" are connected by flanges and bolts. In recent years, tower structures made of special composite materials (below 5 megawatts) have emerged, which have superior strength and a comprehensive performance, but low production results and expensive prices [7]. Therefore, most manufacturers still conduct research on large wind turbines above 5 megawatts based on steel structure towers, and scholars have also conducted many studies on this basis. For instance, [PERSON] [8] used a composite steel beam element with metal wheels as the basic element of the tower body and applied finite element software to study the deformation of the tower body. [PERSON] et al. [9] used a finite element analysis to analyze the coupling behavior of the tower body and blades, and achieved an optimal design of the structure. [PERSON] et al. [10] conducted a finite element analysis on the bolt positions at the connecting flanges between tower sections, exploring the mechanisms of explicit faults and fracture failure issues. In order to balance the aerodynamic forces on multi-blade wind turbines, while increasing the power, effectively reducing the aerodynamic imbalance forces on the rotor and tower and reducing the fracture failures caused by unbalanced impacts, megawatt wind turbines must use the yaw motion to perform windward deflection and positioning [11; 12]. However, during the yaw motion process, the vibration itself, especially the long-term significant LSJ vibration, can also cause safety hazards. Actually, the yaw phenomenon widely occurs in the motion process of many rotating power equipment and fluid-driven power systems; so, the stability of the yaw motion and the stability of the auxiliary motion, as well as the additional effects created by yaw, have been a hot topic for a long time, with modeling theories of various vibration systems and vibration control methods being the focus of the research. The representative studies are as follows. [PERSON] et al.