Nonlinear Dynamic Research Of Involute Spur Gear System

The gear transmission system is widely applied and plays a very crucial role in themechanical, aerospace, shipbuilding and other industries. In recent times, the low vibrationand low noise gear system design assumed as a most important indicator in manufacturing.This enhanced the urgency for studying the theory and technology of vibration and noisereduction. The vibration-related gear dynamics has been widely and intensely researched inthe past few decades.In this dissertation, an in-depth reserach is carried out for involute spur gear system,and formed a theoretical research system mainly contains nonlinear dynamic modeling,experimental research and model validation, nonlinear vibration analysis, tooth profilemodification and dynamic performance optimization. The main contents and innovation ofthis paper are as follows:The lateral-torsional-rocking coupled nonlinear dynamic models are established forordinary involute spur gear transmission and planetary gear transmission, respectively. Themodels mainly considered the influence of geometric eccentricity, center distance deviationand translational displacement on the direction of mesh line, the change of front-sidecontact and back-side contact on the direction of mesh line, the unbalanced inertia forcecaused by geometric eccentricity, the gyroscopic moment caused by the azimuthal variationof transmission shaft and the unbalanced moment along tooth width due to uneven loadsharing.A gear mesh dynamic model is proposed for ordinary involute spur gear transmissionand planetary gear transmission, respectively. The models mainly considered the variationof center distance on backlash, the tooth profile modification, rotation speed flunctuation,center distance variation, the change of front-side contact and back-side contact on meshstiffness. Therefore, this approach made the studies on the coupling effect between thedynamic response and gear mesh parameters possible and describe the state of meshprocess more accurately.Two test platforms are build for two-stage ordinary gear system and single-stageplanetary gear system, respectively. The test method, test theory and data processingmethod are presented, and the experimental research are carried out under several steady-state conditions. The nonlinear dynamic models are established for differentexperimental devices and numerical simulations are carried out. The results show that thesimulation results are in good agreement with the experimental results, and verify thecorrectness of the lateral-torsional-rocking coupled nonlinear dynamic model and the gearmesh dynamic model presented in this dissertation.For single-stage ordinary gear system, the influence of engine speed, support stiffnessand center distance deviation on dynamic load are studied under engine torque fluctuation.The influence of roation speed, backlash and center distance on dynamic load under idlingcondition are also studied. The type of motion under different working conditions areidentified with the nonlinear characteristic analysis method. The results can be used todesign low-vibration and low-noise gear transmission.The influence of tooth profile modification on mesh stiffness and load sharing underquasic-static condition are studied. Based on the lateral-torsional-rocking coupled nonlineardynamic model of spur gear system, the influence of tooth profile modification parameterson dynamic load factor are studied, and then further analyzed its effect on tooth strength. Inorder to reduce the dynamic load of gear system，the reduction of dynamic load factor istaken as objective, the optimization model is proposed, which provide a true reflection ofthe coupling effect of the actual working conditions and the parameters of profilemodifications. The results show that, the dynamic load of gear system is effectivelyreduced, which provide reference for the design of low-vibration and low-noise gearsystem.For a tracked vehicle used gear transmission system, based on the nonlinear dynamicmodels, the dynamic gear mesh force, loading coefficient of planetary gear, dynamicbearing force and dynamic stress of transmission shaft under different gears are analyzed.The influence of gear accuracy and dynamic balance accuracy on dynamic performance ofvehicle gear transmission are studied. Based on the nonlinear dynamic model of geartransmission, a optimization model is proposed which considered the dynamic peformanceof several gears. The optimization platform is set up through the Isight software integratethe nonlinear dynamic programs and solved with NSGA-II method. The results prove thefeasibility of the optimization method and provide reference for the dynamic characteristic improvement of vehicle gear transmission...