Study On Nonlinear Dynamics Of Locomotive Gear Transmission System

With the rapid economic growth and the improvement of people’s living standard, the rapid, safe and comfortable demand of railway transportation is increasing day by day. Rail transport bearing enormous pressure is inevitable, so, research on the various parts of the locomotive becomes very important. The gear system is one of the most important parts of the locomotive, it is in the state of long term maintenance of high speed and heavy load operation in locomotive and its running state is affected by many factors, therefore, to ensure the normal operation of the locomotive, the good condition of the gear system is the premise. Thus, it is of great significance to study the locomotive gear system.This paper takes the locomotive gear system as the research object, and comprehensive consideration of the error excitation, time varying meshing stiffness, meshing damping, bearing stiffness and other factors, the system is modeled and analyzed, and some achievements and progress have been achieved. The main research contents of this paper are as follows:(1) In this paper, a model of three degree of freedom of the bending-torque coupling locomotive gear system is established, the non-dimensional treatment of the model was carried out, and the model was solved by the numerical integration method. By analyzing the influence of the gear speed and the support stiffness on the nonlinear system, it can be found that the movement of the gear system changes with the change of parameters, both of them appeared single cycle, double period and chaos, and it is proved that the gear speed and the bearing stiffness are the strong nonlinear parameters of the system.(2) The Ishikawa method is used to calculate the time varying meshing stiffness of gears, and by the method of piecewise quadratic function fitting, the relative accurate time varying meshing stiffness function equation of the gear is obtained, putting the equation into the model, and the more accurate results was get finally. Finally the relevant conclusions are also verified the correctness of the results.(3) The internal excitation and external excitation of locomotive gear system are considered synthetically. The error excitation of the system, driving force fluctuation moment, meshing stiffness, meshing damping, supporting damping, equivalent mass, driving torque and so on are analyzed. Taking into account the actual situation, the driving torque is obtained by analyzing the slip characteristics of the locomotive wheel.(4) Finally, the stability of the system is analyzed by using Floquet theory, the influe of gear speed and bearing stiffness on the stability of the system is discussed, ar concluded that the results are consistent with the previous nonlinear analysis. In addition, the stability analysis of the system shows that there are three forms of multiple-periodic bifurcation, Hopf bifurcation, saddle-node bifurcation in gear system model movement periodicity change, it was explained how the system was moving into a chaotic motion from a periodic motion.