Nonlinear Vibration Characteristics Of 2K-H Planetary Gear Transmission System With Backlash

The planetary gear transmission system is an important component in the Geared Turbofan.In order to meet requirements of the gear transmission turbofan engine with the high bypass ratio and high thrust,and drive the planetary gear transmission system to develop high speed,heavy load,light weight,etc.,which also causes the vibration generated from the planetary gear system during operation will be increased.And it will have a negative impact on the stability of the engine.Research on the nonlinear dynamic characteristics of the planetary gear transmission system can provide theoretical support for the system’s vibration reduction,noise reduction and structural optimization.In this thesis,with the combination of between theoretical modeling and numerical analysis,the nonlinear dynamics of the planetary gear transmission system is researched as follows:The systematical torsional dynamics model is established by the lumped parameter method,and the vibration differential equation of the system is given.The natural frequency and vibration mode are obtained,and the vibration mode of the vibration mode is summarized.The increasing or decreasing status of the number of planetary gears and the influence of the system parameters on the natural characteristics of the system are analyzed.And the results show that the change of the number of planetary wheels has no effect on the vibration mode of the system mode.The system parameters has an enormous influence of on the higher order natural frequency.According to the actual working state of the planetary gear transmission system,the nonlinear dynamic model of the system bending and torsion coupling is established,with the center displacement of the sun gear.the rigid body displacement of the system is eliminated,and the dimension of the system vibration differential equation is normalized.The calculation formula of the load factor is deduced,and the time history diagram of the load factor of the system is obtained.The results show that when the input speed decreases,the meshing vibration load distribution is more uniform and the load sharing performance is improved.With the increase of the tooth clearance,the uniform load coefficient increases and the vibration is enhanced.Runge-Kutta method is used to solve the vibration differential equation of the system,and the nonlinear response pattern of the system is obtained.The technology tools including Poincare section technology,phase diagram,time history diagram,frequency spectrum analysis technology are combined to analyze the influential rule of meshing backlash,damping,the sun wheel support stiffness on the nonlinear dynamic response,and the results show that with the change of the backlash,meshing damping,the sun gear support stiffness system,the system will behave different response shape.