Nonlinear Dynamic Research Of Locomotive Traction Gear System Based On Cell Mapping Method

With the rapid development of China railway locomotive to high speed and heavy load,the gear is required to have better quality to ensure that it can play normal role without failure in the machine driven system.Therefore,in order to protect the safety and smooth running of the high speed train,it is of great significance to study the dynamics problems of the locomotive traction gear system.In this paper,the gear rotor model is established based on the actual structure of a locomotive traction motor drive system firstly.The first four-order critical speed and mode shapes of the model are calculated by using Riccati transfer matrix method,and the influence of support stiffness variation on the critical speeds and mode shapes is discussed.Finally,considering the vibration displacement size caused by imbalance will affect the normal meshing of the gear pair,the unbalance response of locomotive gear rotor is analyzed in detail.It is found that the working speed could be kept away from the critical speed by increasing the bearing stiffness.In addition,the maximum unbalance amplitude fluctuates near the first-order critical speed,verifying the calculation of the critical speed.The unbalance vibration in the middle of the rotor is most severe,which is very unfavorable to the normal engagement of the gear system.As an important dynamic excitation in gear meshing process,the time-varying meshing stiffness of the gear system is calculated by means of the Ishikawa method,and is fitted by using Fourier series to deeply study the nonlinear characteristics of the locomotive traction gear system.Furthermore,the mechanical model of the locomotive traction gear system is established,and dimensionless processing of the model is then carried out.The cell mapping method and other numerical methods are combined to discuss the influence of the backlash,the pinion speed and integrated error on the global characteristics of the system.The phenomenon of multiple motion states coexistence is found,and the evolution law of attraction domain is revealed.At last,the global dynamics of the system are obtained,which can provide reference for the design,manufacture and nonlinear dynamics research on the locomotive traction gear system.Taking into account the fluctuation of the drive system caused by the change of the wheel and rail adhesion changing,the model of the locomotive traction gear system is established.The nonlinear dynamic characteristics of the system under the creep rate are studied by using the cell mapping method.The coexistence of multiple periodic motions with creep rate changing is discussed,and the influence of creep rate on the dynamic characteristics of the system under different initial values is analyzed.Besides,the influence of the meshing damping on the stability of the periodic solution is discussed by using shooting method and Floquet theory.The results show that the system undergoes periodic motion to chaotic motion,chaotic motion to the periodic motion with the increase of creep rate.At the same time,it is found that the shape of the chaotic attractor has an evolutionary process from instability to stability.The chaotic attraction domain appears sparse until the chaotic motion disappears.While different periodic motions coexist,each attractor is competing for the domain of attraction,reducing the global stability of the system.Under different initial conditions,the system exhibits different bifurcation diagrams,verifying the above multi period motion coexistence.With the increase of the meshing damping,the stability interval of the system becomes wider,and the meshing damping value of stabilizing the system in the large range for creep rate is found.