Study On Dynamic Characteristics Of Gear Transmission System With Pitting Fault

Gear transmission system is the most widely used transmission device in machinery.In the process of mechanical equipment working,the operation state of gear transmission system often plays a key role in the work of the whole mechanical equipment.Firstly,this paper takes the fault simulation test-bed of gear system as the research object,analyzes the thermal effect produced in the process of gear transmission and the effect of thermal effect on the meshing stiffness,and analyzes the effect of pitting on the thermal effect of gear;secondly,the normal distribution theory is used to simulate the location of pitting,and the energy method is used to analyze the meshing stiffness of normal distribution pitting;finally,the results of gear meshing stiffness are analyzed The influence of pitting on the dynamic characteristics of the gear meshing system;finally,the dynamic characteristics of the gear transmission system are analyzed with the wind turbine gearbox as the research object.The main research contents are as follows:(1)The finite element software is used to establish the gear tooth model of health and different degree of pitting failure,and the corresponding thermal boundary conditions are applied to simulate the thermal effect of gear tooth meshing using the thermodynamic theory.The temperature field of gear tooth is analyzed,and the influence of the thermal effect of gear on meshing stiffness is analyzed.The results show that the temperature of both sides of the gear is lower,and the temperature near the middle pitch is higher;when the gear teeth have pitting corrosion,the temperature increases;when the area of pitting corrosion expands along the direction of the tooth width,the temperature of the gear teeth does not increase significantly,but the temperature increases along the direction of the tooth profile;the thermal effect of the gear mesh has little effect on the gear mesh stiffness.(2)The normal distribution theory is used to simulate the location of pitting,and the energy method is used to analyze the influence of different degrees of pitting on the meshing stiffness of gears.The results show that the more the pitting degree is,the more the meshing stiffness decreases.Then,using the finite element method and ISO 6336-1:2006 to calculate the gear mesh stiffness and energy method for comparison,verify the reliability and accuracy of the energy method to calculate the mesh stiffness results.(3)Considering the influence of pitting on the dynamic characteristics of the gear system,based on the analysis of the meshing stiffness of the normal distribution of pitting,the dynamic model of the 6-DOF gear system is established,and the effect of different degrees of pitting on the vibration response of the system is analyzed by using the lumped parameter method and Runge Kutta iterative equation.The results show that when there is pitting,the gear system will be impacted by vibration.The more serious the pitting,the greater the vibration impact.(4)Taking the gear transmission system on the gearbox of wind turbine as the research object,the dynamic model of 16-DOF gear bearing rotor transmission system is established.The vibration response of gear and bearing in gear bearing rotor transmission system is analyzed,and the effect of pitting on dynamic characteristics of gear transmission system is provided.The results show that the impact of pitting on the y-direction and ? direction of the driving wheel is greater than that on the x-direction of the driven wheel,and the impact of gear pitting on the bearing is also smaller.The greater the degree of pitting,the more obvious the impact.