| As a basic transmission component,gear transmission is widely used in marine ships,engineering machinery,wind power generation,aerospace and other fields.It has the advantages of high working stability,constant transmission ratio,strong bearing capacity and high transmission efficiency.At present,the gear system is developing in the direction of high precision,light weight,high power,high speed,etc.,while the effects of meshing coupling,impact,error,structural system coupling and so on cause the system vibration and noise problems to become more and more obvious,which seriously restricts the development of the gear system.Therefore,accurately establishing the system vibration and noise prediction model and optimizing its dynamic performance has become a hot topic in the gear industry.At present,noise prediction mainly uses a combination of finite element and boundary element methods,which is large in scale,cumbersome in process,and inefficient,making it lose its timeliness in the product design stage.Therefore,it is of great theoretical significance and engineering application value to carry out the research on the fast calculation and optimization of vibration and noise of the parallel confluence gear system.The research object of this thesis is the marine parallel confluence gear system,which is a complex time-varying vibro-impact coupling nonlinear system.The energy distribution and propagation law of vibration and noise under multi-source non-stationary excitation are unclear,which easily leads to blind and inefficient vibration and noise control.Aiming at the problems such as significant impact excitation,complex dynamic characteristics and long noise prediction period of the parallel confluence gear system,this thesis carries out the research on meshing impact mechanism,the analysis of coupling vibration characteristics of transmission and structure system,the fast calculation method of noise,the research on the multi-objective collaborative optimization design method of mass-impact-transmission error-vibration-noise,and provides ideas for the fast calculation and optimization of vibration and noise in the design stage of the gear system.The main research contents of this thesis are as follows:(1)The mathematical model of meshing impact of involute gear under load deformation is established.Based on Hertz contact theory and Palmgren cylindrical linear elastic contact model,the meshing impact force of parallel confluence gear system is calculated;In view of the large error of the existing impact time algorithm,a kinematic geometric method is proposed to calculate the impact time based on the established meshing impact mathematical model;Finally,according to the actual working condition of the gear,the dynamic contact finite element analysis of the gear system is carried out,and the meshing impact force and impact time are extracted.Through comparative analysis,the rationality of the analytical calculation method is verified.(2)Considering the impact excitation,stiffness excitation and error excitation into the model,establish the dynamic model of the parallel confluence gear transmission system,study the dynamic characteristics of the gear transmission system without considering the box,and explore the impact of impact excitation on the parallel confluence gear transmission system;Then,a dynamic modeling method for the coupling of the parallel and converging gear transmission system and the structural system is proposed,and the coupling dynamic model of the parallel and converging gear system considering the box structure system is established,and the dynamic response characteristics of the structure and transmission coupling system are analyzed.(3)In view of the long time period of noise prediction and calculation of the gear system at present,based on the empirical formula,the accuracy and applicability of the noise prediction formula for the parallel confluence gear system are studied,the noise prediction formula is modified,and a fast calculation method for the noise of the parallel confluence gear system is proposed to realize the fast calculation of the noise of the parallel confluence gear system,laying the foundation for its multi-objective optimization.(4)Taking gear module,helix angle,tooth number and other transmission system and structural system parameters as design variables,gear strength,assembly position,transmission ratio and other constraints,and taking transmission error,meshing impact,vibration acceleration of gear and box,radiated noise and mass of parallel confluence gear system as objective functions,a multi-objective collaborative optimization model of transmission error,impact,vibration,noise and mass of parallel confluence gear system is established,Carry out the rapid calculation of the vibration and noise collaborative optimization of the coupling gear system combined with the structural system,realize the rapid prediction of the dynamic response and the rapid optimization of the system parameters at the research and development stage,and compare and analyze the optimization results with those before optimization,and obtain better optimization results. |
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