| The research on nonlinear dynamic and load sharing characteristics has important significance for gear transmission system, including increasing gear system’s fatigue life, decreasing the vibration, lowering the noise and improving the motion stability. However, some strong nonlinear factors make the gear transmission become a hard and hot point in the current research. The helicopter’s main reducer is set as the research target in this paper, and the theoretical design guideline and technical support are provided for gear transmission system by studying the characteristics of gear system’s load sharing and nonlinear dynamics.(1) The non-linear dynamic behavior of a spur gear transmission is investigated. The model of a spur gear train with tooth surface and multiple clearances is established, and the governing equation of the system is derived. The global bifurcation and chaos motion characteristics caused by input speed, backlash, clearance, friction coefficient and mesh damping are analyzed.(2) The characteristics of load sharing and nonlinear behavior are studied. The nonlinear dynamics model including time-varying meshing stiffness, backlash, bearing clearance and synthetic transmission error is proposed, and the transverse-torsional coupled governing equation is derived. The effects to system load sharing caused by input speed, supporting stiffness and bear clearance of sun gear, backlash of the sun-planet and planet-ring meshing pair, eccentric error of the sun and planet are analyzed. The theoretical result is validated by test. At the same time, the global bifurcation characteristics and the routes to chaos motion caused by input speed, backlash, bearing clearance and mesh damping is investigated. A new method to analysis, design and evaluate the new developed planetary gear train system is presented, which took load sharing and nonlinear behavior analysis into consideration.(3) The dynamic characteristics of the double stage planetary gear train are studied. The model considering time-varying meshing stiffness, synthetic transmission and transverse displacement of the sun gear, planet and ring gear is presented. The system’s dynamic transverse-torsional coupled governing equation is established and solved by Fourier series method. The load sharing characteristics of double stage planetary gear train caused by input speed, eccentric error and supporting stiffness of the sun gear, the ring gear’s supporting stiffness and rotation stiffness of the first stage’s carrier are analyzed. The trajectory of the sun gear center under different rotation speed is investigated. The method of using transverse displacement degrees to simulate the fixed ring gear with long and thin wall is proposed, and the coupling effects under different parameters are analyzed.(4) The nonlinear characteristics of the double stage planetary gear train are investigated. The dynamic model including transverse displacement degrees, bearing clearance, backlash, time-varing mesh stiffness and synthetic transmission error is proposed. The system governing equation is derived and solved by Runge-Kutta numerical integration method. The nonlinear behavior and the routes to chaos motion caused by input speed, backlash and bearing clearances are analyzed, and the coupling effects between first and second stage is studied as well.(5) The dynamic vibration characteristics of helicopter’s main reducer are studied. The dynamic model of a typical kind of helicopter’s main reducer is proposed by the method of lumped mass parameter. The vibration differential equation is derived and solved by Fourier series method. The inherent characteristic is obtained, and the effects to each gear stage caused by input speed and system power are analyzed. |
PDF Full Text Request