| Spiral bevel gears are widely used in the transmission systems of aviation, spaceflight and engineering mechanical transmission systems, its operating characteristics have a vital influence on the whole transmission system. Usually the external loads and drive equipments are multifarious, so the external excitation which is aroused by motor or loads will appear, and the internal excitation which is aroused by time-varying meshing stiffness, deviation of the gear transmission or tooth gap will appear too. Thus the working performances of spiral bevel gear transmission system are so complex. Especially in aviation, spaceflight, and automobile area, the spiral bevel gear is used in high speed, heavy load conditions, in addition its must be provided with low weight and high reliability, so it's indispensable to do the deep research on the dynamic characteristics of spiral bevel gear transmission system.This thesis focuses on a spiral bevel gear transmission system in aero-engine, and its dynamic model is established, according to the dynamic model, researche on how the parameters of gear transmission system influence the dynamics characteristics of the whole transmission system. That will be given rise to not only important practical value for spiral bevel gear transmission system, but also important theoretical meaning for the dynamical design of complex gear transmission system. The major works and innovation accomplishments of this thesis are listed as follow:(1) Base on the gear meshing theory, the equations for tooth surface of spiral bevel gear are established, and the calculating program for meshing points on spiral bevel gear surface has developed using vector analytical method and tooth contact analysis. 3D finite element contact model of spiral bevel gear is established by UG (Unigraphics) software.(2) The comprehensive elastic tooth deformation of spiral bevel gear has calculated by contact finite element method, thus the comprehensive time-varying stiffness curves in two gear meshing periods is plotted, and then, the equation for time-varying stiffness has been acquired according to the stiffness curves by fouriertransform algorithm.(3) The couple torsional vibration dynamic model and vibration equation are established, the fluctuant excitations such as input torsion, stiffness and meshing stiffness...etc are considered in the model.(4) The torsional vibration equation is a typical two factorial differential equation group. A fifth order changing step length and self-adapting Runge-Kutta numerical integration routine is introduced to solve the dynamic equations, and the dynamic responses of gear transmission system with variable parameter excitations are gotten, the analysis and comparison of those responses are proposed.The results which are gotten through the research on the dynamic characteristics of spiral bevel gear transmission system show that the global dynamic qualities of transmission system are relatively poor when the damping is smaller, the exciting frequency is higher or the stiffness of transmission shaft is smaller.
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