Research on nonlinear dynamic performance of the central bevel gear transmission system in aero-engine with complex excitation

For the requirement of the vibration control and fault diagnosis of the central bevel gear transmission system in an aero-engine, this paper proposes a 12-degree-of-freedom dynamic model for the first time in order to investigate nonlinear dynamic behavior of the central bevel gear transmission system considering the internal and external excitations. The dynamic model is developed by the use of lumped parameter modeling. Time-varying meshing stiffness, gear backlash and gear transmission error are included in the internal excitations, the input power of the central bevel gear transmission system, the speed fluctuation of the driven shaft and the high-pressure rotor unbalance excitation are included in the complex external excitations. Using the bifurcation diagram, the largest Lyapunov exponent, time domain diagram, frequency domain diagram, phase diagram and Poincaré map, the effects of input power change, driven shaft speed fluctuation excitation and high-pressure rotor unbalance excitation on the complex nonlinear dynamic behavior of the central bevel gear transmission system are analyzed. The increase of input power, reduction of speed fluctuation and control of high-pressure rotor unbalance are beneficial to expand the stable area of the system.