Study On The Dynamic Characteristics Of Multi-Excitation Gear Bearing System With Varying Stiffness

As China enters the "14th Five-Year Plan" stage,the wind turbine application market is gradually expanding as clean energy.Double-fed wind turbines have a large quantity and the working environment is tough.Due to the nonlinear structure,the excitation of the high-speed gear transmission system of the wind turbine speed increase gearbox is more complex,which is prone to damage the speed increase gearbox,especially the part of high speed gear transmission system Therefore,this paper studied and analyzed the dynamic response of multi excitations wind turbine gear bearing system with the state of health and faulted.The research results provided a theoretical basis for wind turbine structure optimization and fault diagnosis and had certain guiding significance.The study of this article had certain scientific significance and engineering practical value for the monitoring and maintenance of gear transmission system healthy operation status for wind turbine.This article taked the high-speed gear transmission system of doubly-fed wind turbine speed-increasing gearbox as the research background.Firstly,the dynamics model of the 8-DOF gear bearing coupling system was constructed based on the gear meshing theory and Newton’s law.The dynamic responses of the gear-bearing coupling system with multi-excitations were obtained by using the fourth-order Runge-Kutta numerical solution method.Secondly,combined with the operating environment of doubly-fed wind turbine speed increase gearbox high-speed gear transmission system,considered rolling bearing time-varying stiffness motivate,the time-varying mesh stiffness of gear and integrated transmission error and others to analyzed the influences to the vibration response from the change of system speed,rolling bearing waviness amplitude and waviness parameters such as wavenumber changes.Finally,the timevarying meshing stiffness of the gear under different propagation length of crack at the tooth root was analyzed,the dynamic model of the crack fault gear bearing system under the influence of waviness excitation was established,and the influence law for the dynamics response of the gear bearing system with different crack propagation lengths was analyzed through simulation.The correctness of the crack fault gear system model was verified by experiments,and then verified indirectly the correctness of conclusions.The results show that the mechanism of different excitation acting on the gear bearing system is different,and the influence on the dynamic characteristics of the system is also different.The larger the rotating speed is,the more obvious the meshing frequency and its multiple frequency components.The amplitude of the rotation frequency of the driven bearing cage is positively related to the amplitude of the waviness.The vibration amplitude of the frequency multiplier for the driven gear becomes larger with the increase of the waviness number.As the influence of the waviness excitation,with the continuous expansion of the crack length at the root of the gear tooth,the impact phenomenon caused by the crack becomes increasingly obvious,the amplitude of the meshing frequency and its frequency doubling component in the system is slightly changed.Finally,the experimental verification is carried out.By comparing the experimental results with the simulation results,the correctness of the model established in this paper is proved,and then the correctness of the conclusions obtained in this paper is verified.