Kinetic Characteristics Of Torque Split Gear Transmission System

Parallel axes' split-torque transmission system has the advantages of small volume, light weight, high speed-ratio and efficiency. Therefore, it is widely used in the transmission systems of helicopters and other aircraft, whose requirements are especially demanding and the power transmitted are very great. Usually the external loads and drive equipments are multifarious, so the external excitation which is aroused by motor or loads will appear, and the internal excitation which is aroused by time-varying meshing stiffness, deviation of the gear transmission or tooth gap will appear too. Thus the working performances of parallel axes' split-torque transmission system are greatly complex. In order to optimize the split-torque transmission system in the future, it's indispensable to do the deep research on the dynamic characteristics of it.This thesis focuses on parallel axes' split-torque transmission system in a helicopter's main gearbox, and its dynamic model is established. According to the dynamic model, the laws how the parameters of this system influence the dynamics characteristics of the whole transmission system are investigated. That will be given rise to important theoretical meaning for the dynamical optimization of the system's torque splitting. The major works of this thesis are listed as follow:(1) By using Lumped-mass Method, the torsional dynamic model is proposed to predict the dynamic characteristics of parallel axes' split-torque transmission system. This model includes external load, general transmission errors, time-varying stiffnesses, backlashes and meshing dampings et al. According to this model, the non-linear dynamic differential equations are establishes.(2) The natural characteristic of system is analyzed and natural frequencies and principle mode shapes are solved by Subspace Iteration Method.(3) Employing variable step size Gill integration method, the governed nonlinear differential equations are solved. The four groups of steady state responses are categorized to show the strong-nonlinear behavior of parallel axes' split-torque transmission system, namely harmonic, sub-harmonic, quasi-periodic and chaotic response. Based on time history, phase plane plot, Poincare map and FFT spectra, the classification criteria of the steady state responses are proposed.(4) Influences of system parameters, such as backlashes, external load, amplitude...