Analysis On Gearbox Vibration And Research On Optimization Of Vibration Noise Reduction Structure

With the development of modern industry,ships are now heading towards high speed,low consumption and high performance.Various high-precision and highefficiency industries are adopting the gear transmission systems,which is accompanied with vibration caused by gear meshing,as well as the radiated noise caused by vibration.While most mechanical structures are increasingly pursuing weight reduction,due to the increasing power of the transmission system,structural vibration problems have become more and more serious.Structural vibration will not only shorten the working life of mechanical equipment,but also generate radiated noise.Over time,it will also affect the physical and mental health of operators.Therefore,the study of vibration and noise of the gearbox is important.The main vibration excitation source of the gearbox is generated by meshing,according to this,the thesis analyzes the radiated noise of the gearbox based on the internal excitation,and optimizes the design of the structure for the position where the structural vibration is more serious.At the same time,High frequency noise generated by gearbox is analyzed by applying the statistical energy method.First,the thesis introduces the establishment of the finite element model of the gearbox.In order to avoid damaging the gearbox from the resonance phenomenon,a modal analysis of the gearbox is carried out,in which the intrinsic mode and natural vibration mode are analyzed,and the meshing excitation frequency is compared with the natural frequency.Based on Abqus dynamics,the thesis studies the dynamic excitation of the gearbox,develops an analytical model of the gearbox dynamics,figures out the bearing support reaction forces of the main and driven shafts.Besides,the thesis transforms the result to frequency by applying Fourier,analyzes the frequency generated by the peak value,then verifies the validity of the simulation model by comparing the meshing frequencies of the gear.Secondly,in order to analyze the magnitude of the gearbox radiated noise,the thesis establishes the corresponding acoustic boundary element model in Virtual.Lab Acoustic,and sets up four measuring points around the gearbox.By analyzing the field point sound pressure power curve to get the radiated noise;The thesis also analyzes the contribution of acoustic panel to gearbox In order to obtain the location of the gearbox noise source.By using the information provided by the acoustic contribution,the thesis tries to find areas that need to be optimized urgently,thus laying a foundation for the next structural optimization of the gearbox.In order to reduce the vibration and noise of the gearbox,the thesis carries out frequency response analysis for four measuring points,and obtains the vibration displacement of these points.Based on the multi-objective optimization method in optistruct,the position and thickness of the stiffener are topologically optimized.In order to verify whether the vibration and noise of the gearbox after structural optimization are reduced,the thesis remodels the optimized model and learns that the response of each point has been reduced.Through the comparison of radiated noises,it is found that the mid-and low-frequency noise is reduced,which verifies the effectiveness of the noise reduction effect after the gearbox is optimized.Finally,based on the statistical energy method,this paper establishes the SEA analysis model of the gearbox to study the high-frequency noise,and describes the principle of the statistical energy method and the modeling process.In this thesis,the model is simplified to get parameters of the statistical energy method.With the help of the VA one to divide the subsystem and obtain the three parameters of the statistical energy method,the corresponding solver is set up,and the high frequency noise of the gearbox is analyzed to obtain the high-frequency radiated noise at four measuring points before and after structural optimization.Through comparison,the effectiveness of statistical energy method for solving high-frequency noise and vibration,as well as the effectiveness of stiffener optimization for reducing high-frequency noise are verified.