Abstract: A nonlinear dynamic model of a torque-split gear transmission system is presented to analyze the nonlinear dynamic characteristics. This model includes backlashes, time-varying stiffness, composite transmission errors, damping, and external excitation, etc. The PNF(Poincaré-Newton-Floquet) method is used to solve the dynamic differential equations. Four kinds of forced steady state responses, i.e. simple harmonic, sub-harmonic, quasi-periodic and chaotic responses, are obtained for different parameters and classified based on time histories, phase plane plots, Poincaré maps and fast Fourier transform spectra. The results show that the system has highly nonlinear dynamic characteristics and should be researched more deeply by using nonlinear vibration theories.

Key words: Chaos, Nonlinear dynamic response, Split-torque gear transmission, Sub-harmonic response