Dynamic Analysis And Optimization Of Spiral Bevel Gear System

Spiral bevel gear including curve- tooth bevel gear and hypoid gear, is widely used in various machines and equipments. As the spiral bevel gear unit advances towards large-scale, high-speed, lightweight, high-precision, the vibration and noise reduction has attracted attention, so its dynamic performance analysis and optimization has become a new research hotspot. Presently, the dynamic optimum design of gear system is still quite difficult and novel contents in engineering structure field, it is one of the leading edge of the subject, to carry out its research not only has practical engineering background and practical value, but also has important theoretical significance.The thesis subject is supported by National Project of Scientific and Technical Supporting Programs. Dynamic performance of spiral bevel gear is analyzed and optimized by combination of contact mechanics, structural dynamics, principle of gear engagement, optimization theory, etc. The research work presented in this thesis can be summarized as follows:①The basic equations of curve-tooth bevel gear and hypoid gear tooth profile curve are derived, and the geometry model and static finite element model of gears are established. The contact performance of gear transmission in operation is analyzed by using the software of ANSYS, and then the change laws of Von Mises stress and contact stress of gear tooth are obtained.②The dynamic contact analysis for curve-tooth bevel gear and hypoid gear is carried out by using finite element method, and the mesh impact excitation and dynamic stress distribution is obtained.③Hypoid gearbox is simplified to linear system by means of assembly modal analysis theory, then modal analysis is carried out and the results is compared with the experimental results. Considering structural parameters as the design variables, volume, static stress and displacement as the state variables, the multi-frequency optimization model of hypoid gearbox is built with a target of avoiding the excitation frequency. Then it is solved by means of the sub-problem approximation method combining with the first order optimization method.④Considering the distortion of gear engagement, bending deformation of shafts and support stiffness of bearings, the 3D non-linear dynamic contact FEM model is established, and the dynamic support forces of bearings are calculated. ⑤The dynamic response analysis is carried out while the support force as the input load. Considering the mean square root of vibration acceleration as the objective function, structure parameters of gearbox as design variables, volume, static stress and displacement as the state variables, the dynamic response optimization model of hypoid gearbox is built. Then the optimum design sets can be obtained by means of sub-problem approximation method.