Research On Bending-torsion Coupling Vibration Of A Rotor-gear Transimission System With Damping Ring

As is known in the field of mechanical transmission, the gear transmission system is widely used in power and motion transmission device in rotating machinery field, such as aeroengine accessories transmission system, automobile powertransmission systems, tranmission system of helicopter, etc. Due to the poor working condition, gear transmission is easily affected by vibration and impact. As a result, research on vibration reduction of gear transmission system has been one of the most meaningful studies in mechanical transmission. Damping ring technique, as a quite effective way to suppress the vibration of gear transmission, is widely applied in mechanical engineering due to its advantages, such as compact structure and simple process, etc. Up to now, most of researches on damping ring are mainly studied based on the empirical formula and a large amount of experiments, which may lead to large research cost and long production cycle. Thus, theoretical analysis of gear-damping ring system is particularly necessary.In this paper, together with the principle of the dynamic vibration absorber and based on lumped parameter method(LPM), a dynamic model for torsional vibration of a gear-damping ring system is established by considering the transmission error, where the friction between the gear and the ring is described by the Stribeck friction model. The harmonic balance method is employed to work out the approximate analytical solution of the system. Then, a practical example is given to compare the analytical results with those from numerical simulation in terms of Runge-Kutta method and to illustrate that the proposed analytical approach is valid. After that, the amplitude-frequency characteristics of the system under different friction conditions are analyzed. Meanwhile, the comparison of the Stribeck friction model and Coulomb friction model are performed. The simulation results reveal that the installation of damping ring can not only suppress the resonant amplitudes significantly but also has slight influence on frequencies. Additionally, the error of the Stribeck friction model and Coulomb friction model is found to be small but increase with the pressure between the gear and the ring. Thus, when the friction between the gear and the ring is relatively large, the Stibeck friction model shoule be considered in such sytems.According to the experimental device of aeroengine, a bending-torsion coupling dynamic model of rotor-gear transmission system which has 8 DOFs is established based on the LPM. In the simulation study, the natural characteristics of this proposed model are analyzed and then compared with the results from the corresponding finite element model performed in ANSYS. The simulation results reveal that the proposed 8-degree model is valid. In addition, the influence of the meshing stiffness on the natural characteristics are analyzed and the resonant amplitudes of the system are obtained by employing the Runge-Kutta method.In the same way, by installing the damping rings on the rotor-gear transmission sytem, a bending-torsion coupling dynamic model of damping ring-rotor-gear transmission system which has 10 DOFs is established based on the LPM. RungeKutta method is then employed to analyze the natural characteristics of this model. Taking resonances of some DOFs for examples, the resonant amplitude-frequency of the system is discussed as well. Meanwhile, taking the installation stiffness and damping as well as the friction between the gear and the ring as variables, the influence of these parameters on the dynamic characteristics of the system is analyzed. The simulation results reveal that the structural parameters of the damping ring have insignificant effect on low order resonances of the system but have significant effect on high order resonances. When the three parameters of the damping ring increase within a certain range, the resonant peaks of some DOFs in the system is reduced, including the bending resonances of rotor and torsional resonanc es of gear. Meanwhile, it is found that the resonance of some DOFs may disappear or occur with the change of the three parameters. Additionally, there are optimal values for installation stiffness and damping that can lead to the most effective vibration suppression of the system.