Research On Dynamic Characteristics Of Gear System Considering Nonlinear Meshing Stiffness

Wind energy is a kind of clean and renewable energy.At present,wind energy plays an increasingly important role in China's sustainable development strategy.Therefore,the installed capacity of wind turbines in China is increasing year by year,which puts forward higher requirements for the stable operation of wind turbines.As the main transmission mechanism of the wind turbine,the gearbox is also the main location of the failure of the wind turbine.As the most important transmission mechanism in the gearbox,the gear bears complex internal and external excitations,which will inevitably cause faults in the harsh working environment.Among them,gear crack is one of the common faults.The tangential force on the tooth of the gear will make the crack continue to increase,which will eventually lead to the fracture of the tooth of the gear,which will seriously affect the normal operation of the wind turbine and cause great losses to the economy.Therefore,the study of the dynamic characteristics of the normal gear transmission system and the gear transmission system with cracks provides a theoretical basis for the improvement of gear box design,gear box fault diagnosis and state monitoring.The main research contents are as follows:(1)Considering the precise transmission contour,the Hertzian contact stiffness,fillet foundation stiffness,bending stiffness,shear stiffness and compression stiffness of the gear system were obtained based on the energy method,and then time-varying mesh stiffness expressions of single and double teeth of the gear system were also obtained.(2)Considering gear tooth clearance,time-varying mesh stiffness and gear transmission error,a 6-dof gear model was established based on the lumped parameter method.The fourth order Runge-Kutta numerical integration algorithm is used to solve the differential equation of gear transmission system.The influence of gear speed on gear dynamic characteristics in all directions is analyzed by time domain and frequency diagram.(3)Considering the influence of gear tooth crack fault on the gear's bending stiffness,shear stiffness and axial compression stiffness,the time-varying mesh stiffness of the gear system with root crack fault is calculated.Matlab simulation software was used to analyze the dynamics of gear transmission system with root crack fault.(4)The vibration characteristics of healthy gear transmission system and gear transmission system with root crack fault are verified by tests.(5)Considering the error of machining,assembly and other errors,the actual center distance of the gear system and the theoretical center distance will be different,and the influence of the center distance of the gear system on the dynamic response of the system will be analyzed.