Nonlinear Dynamic Analysis And Research Of Helical Gear Transmission System

Wind turbine gearboxes are one of the core components of wind turbines,and their operational stability affects the efficiency and quality of the entire wind turbine.However,the working place of wind power gearbox is mostly in the wind,such as mountains,wilderness,beaches,islands,etc.The working environment is harsh,and the load and wind speed are irregular.Therefore,the gear transmission system in the gearbox often has broken teeth,pitting,wear,gluing and other failures causing significant losses.The gear transmission system comprises a one-stage planetary gear transmission system and a third-stage helical gear transmission system,therein the third stage is a high speed stage.If the helical gear in the high-speed stage fails,the dynamic characteristics of the gear transmission system are most affected,and the impact on the operational stability of the whole system is also the most obvious.Therefore,it is of certain engineering significance to research the third-stage helical gear transmission system considering faults.In this paper,the third-stage helical gear transmission system in wind turbine gearbox is taken as the research object,and the nonlinear dynamics of gear transmission system considering nonlinear factors,random disturbance factors and common fault modes of gears are analyzed and deeply studied.The main work of the thesis includes the following aspects:(1)Explain the excitation and common nonlinear factors in the gear transmission system,establish the mathematical model of the tooth side clearance,transmission error,random disturbance excitation and external torque.Calculate the time-varying meshing stiffness of the helical gear based on the energy method and simplify it reasonably.(2)Simplify the model of the third-stage helical gear,and establish a spatial six-degree-offreedom nonlinear dynamic model of the helical gear transmission system considering various nonlinear factors and random disturbance factors.(3)Explain the three motion forms of the nonlinear system and the commonly used analysis methods.The system dynamics equations are solved based on the fourth-fifth-order Runge-Kutta method,and the feasibility and effectiveness of these methods are verified by the above analysis methods.(4)Based on the control variable method,the parameters of load and speed in wind turbine gearbox are analyzed.The meshing stiffness is discussed under four conditions: light load and low speed,light load and high speed,heavy load and low speed and heavy load and high speed.The influence of three system parameters,the flank clearance and the damping ratio on the dynamic characteristics of the system are based on the above conclusions,a reasonable selection method of the system parameters is given to ensure the stability of the system motion.(5)For the four types of faults commonly found in gear transmission systems: broken teeth,pitting,wear,gluing,based on the principle of failure to establish a corresponding mathematical model,in which the tooth surface is accelerated to accelerate the gear wear to increase the flank clearance,and wear the resulting effects of the failure are discussed together.The system dynamics model considering gear broken tooth fault,pitting fault,wear and gluing fault is solved separately,and nonlinear system analysis method is used for analysis.