Numerical Simulation Of Dynamic Response And Radiation Noise Of Gearbox

Gear transmission has an irreplaceable advantage comparing with other transmission types because of its constant power and high transmission efficiency. It has become one of the most key components in modern industry. With the rapid progress of science and technology, gear equipments are developing fast towards the large-scale, high-speed, lightweight and high precision, meanwhile, it puts forward higher requirements for vibration and noise reduction of gear system. Therefore, numerical simulation of dynamic response and radiation noise of gearbox has important theory significance and engineering application values.The thesis is supported by National Project of Scientific and Technical Supporting Programs during the Eleventh Five-Year Plan. Combining with principle of gear engagement, mechanical system dynamics, and acoustic theory, the numerical simulation of dynamic response and radiation noise are studied for gear system which includes transmission system and structure system.The research work presented in this thesis can be summarized as follows:1) The dynamic finite element model for gearbox housing and gear system are constructed. Using the software of ANSYS, the finite element modal analysis is carried out by the block Lanczos method, and the natural frequencies and principal modes are obtained.2) The calculation method of interior excitation which contains the stiffness excitation, the error excitation and the mesh impact excitation is studied. Firstly, the finite element model of gear transmission is established, and then the mesh stiffness excitation of tooth pair is calculated by using the software of ANSYS. Secondly, the error exaction is described by half sine function according to gear precision grade. Thirdly, the dynamic finite element model for contact problem of gear transmission is established, the impact excitation of tooth pair is obtained by using the software of LS-DYNA. At last, the inner dynamic excitation curve of gear system can be obtained by integrating these excitations.3) Considering the several internal dynamic excitations, the dynamic finite element model of gear system is established; the time domain responses of vibration displacement, vibration velocity and vibration acceleration of gearbox are calculated by means of the full method in transient dynamic analysis module of ANSYS.4) By Fourier transform, the time domain responses of vibration displacement of gearbox surface nodes are transformed to the frequency domain responses which act as the boundary excitation condition. Based on the dynamic finite element model of gearbox, the acoustic boundary element model is built. By the software of SYSNOISE, the surface acoustic quantities of gearbox are solved by the direct boundary element method, and then the radiation noise of field points is calculated.5) A-weighted octave radiation noise is measured on the general test bench, and then the test results are compared with the corresponding numerical simulation results.