Research On The Nonlinear Dynamic Characteristics Of High Power Marine Gearbox Transmission System

With the rapid development of science and technology,the high-power marine gearbox transmission device,as one of the most important equipment of ship propulsion system,is developing towards high rotating speed,heavy-load,high stability,low vibration and low noise.Gear box performance requirements and market demand also gradually increased,which put towards higher requirements on the dynamic transmission characteristics of gearbox transmission system and the manufacturing capabilities.In order to reduce the failures of the gearbox transmission system caused by the bad vibration,improve the service life and the reliability of gearbox system,and controlling the noise of the system,it is necessary to drive dynamic characteristics analysis for high-power marine gearbox transmission system.The thesis is supported by National Natural Science Foundation,aims at a certain type of high-power marine gearbox.The transmission system is modeled and numerically analyzed by the lumped parameter method.The main research work in this paper can be summarized as follows:(1)A 24-degree-of-freedom dynamic model coupled flexional,torsional,axial and pendular motion of a high-power marine gearbox transmission system,which includes time varying mesh stiffness,gear mesh error and meshing impact and the external excitation caused by the torque fluctuation of marine diesel engine,is developed based on system dynamics,nonlinear vibration theory and the lumped parameter method.(2)In view of the dynamic model established in the previous article,the nonlinear dynamic differential equations of the system is solved by the Runge-Kutta algorithm,which is built-in the Matlab.Based on the numerical solution,the response of time domain and frequency domain under different excitation conditions is drawn.The different influences on the vibration response by external excitation,static transmission error and backlash of the gear pairs are discussed according to the curves.(3)The tooth profile modification theory is analyzed,the t ooth profile modification model is established,and the three elements of the tooth profile modification are solved.The dynamic characteristics of transmission system with straight line function,conic function and special curve function are studied by numerical method.To analyze the variation of single tooth engagement load and static transfer error,the analysis model of first stage meshing gear pair system is constructed in the software of Romax.The research of this paper can provide some theoretical references for the engineering design of the high-power marine gearbox transmission system and laid the foundation for the control of noise and vibration.