Study On Some Problems Of Dynamics About Gear Transmission System

Gear transmission system is one of the most commonly used in mechanical transmission form, because of the constant power transmission characteristics, it have irreplaceable advantage. At present, Gear system is becoming high speed, heavy load, lightweight, high precision and automation, it puts forward higher requirements on its dynamic performance. Gear system dynamics, nonlinear vibration noise and its control has become one of the very active frontiers in the current scientific research.Auto transmission,1.5MW windbox and accessories is the main structure of power transformation and transmission mechanism based on their internal gear transmission system. They are study object of this paper, integrated application of mechanical vibration, the finite element theory and analysis method, the multi-body dynamics method, intelligent optimization methods, lumped parameter method, the boundary element analysis method modal synthesis method and so on. Their Spur and helical gear coupling transmission systems were studied on dynamics characteristics, internal motivation, the modification, vibration deduction and optimization, and dynamic impact strength of the vibration noise optimization problems.More specifically, this paper completes the following work:(1) Studied the high-speed load gear shafting dynamics and travelling wave resonance characteristics with elastic support; Shafting dynamics model is established considering the coupling effects of multiple gears meshing and bearing elastic support. the distribution of critical speed and resonant response was analyzed under different support stiffness. Using the method of strain energy density distribution this paper analyzed the harm of travelling wave resonance to the bevel gear shaft.(2) Based on static contact method, the time-varying meshing stiffness was got, incentives was synthesized by tooth surface error and mesh impact gear meshing and time-varying meshing stiffness. Based on dynamic contact analysis, the internal meshing excitation of flexible helical gear shaft system was studied. The effect of the gear pair center distance changing and elastic shaft -bearing to internal meshing incentive was contrastly analysised. The elastic axis-bearing led to increased frequency components of meshing incentives. And the frequency components distributed around the meshing frequency, the frequency doubling and frequency division. The conclusion is consistent with the experiment.(3) Based on explicit dynamics and multibody dynamics method, the spur and helical gears modification method was proposed. By using multi-body dynamics method the gears meshing error of gear pair caused by deformation of shaft system was got. Considering the meshing error, the finite element model of modification gear was established. The biggest stress on tooth face was been discriminant basis, using explicit dynamic method as a solution and the genetic calculate, the modification parameters were optimized. This modification method conforms to the engineering practice; selected modification parameters can significantly reduce the tooth surface stress in actual working conditions.(4) With helical planetary gear transmission system as the research object, established lumped parameters dynamics model of helical planetary gear transmission system. Consider installation error, machining error and the time-varying mesh stiffness and other factors, dynamic characteristics of planetary gear system was studied. This study shows that the sun wheel is obviously affected by the unbalanced load of the planetary gear train. Because of the influence of error the vibration displacement index increased significantly, and vibration displacement is cyclical fluctuations.(5) Based on elastic gear-shaft-bearing mode, the method of obtaining gearbox case dynamic bearing incentive was proposed, which was used for the gearbox case noise analysis. Established the gearbox input, output and differential bearing incentive calculation model, and applied bearing dynamic incentive on the gearbox case bearing support, the surface vibration velocity was obtained by simulation. Then gearbox case boundary element model was established, through the noise analysis of distribution within the scope of the noise. Through the analysis of the noise transmission the noise distribution of surface and acoustic field and transmission noise mainly position was got. This method in obtaining the bearing vibration force of transmission shell take into the influence of elastic shaft-gear-bearing, bearing vibration force is more reasonable, the precision of noise analysis is higher.(6) Putting forward the Matlb combined with Ansys APDL language, half parameterized model of gear shaft was established. Gear shaft were studied in extreme conditions of the dynamic strength and structural optimization. Development of the gear shaft system dynamic strength and optimization analysis software. Respectively using the implicit and explicit dynamic method the stress of the gear shaft was analyzed under impact load.Through comparisons and analyses, the stress distribution obtained by two kinds of methods is basicely consistent, but dynamic stress under dynamic impact load is greater than the balance stress. The dynamic impact stress level and the maximum stress distribution obtained by explicit dynamic method is more close to experimental results.(7) Continuous parameters dynamics differential equation of gear shaft rotor system was established based on modal synthesis method, Natural frequency and vibration shape of gear shaft rotor system composed of the flexible shaft-flexible gear plate-elastic tooth were analyzed, And the influence by the stiffness and quality of the gear shaft and gear plate for system inherent characteristics was analyzed.