The fatigue failures caused by the vibration often happen in the gears of the aero-engines

so it is urgently necessary to analyze the cause of the vibration. The self-excited vibration of the thin spur gear was studied based on the energy method and a theoretical method used to predict the self-excited vibration was proposed. The expressions of the excitation work and damping work to the travelling wave vibration of the gear were derived. By analyzing the change of the system energy

the likelihood of the occurrence of the self-excited vibration for the thin spur gear was verified in theory

while the condition and gear load in occurrence of the self-excited vibration were also determined. Through the numerical simulation

the influences of the contact ratio

nodal diameter and damping ratio on the stability of the self-excited vibration were studied. Results show that the self-excited vibration will occur in the backward travelling wave of the driven gear and the forward travelling wave of the driving gear in the underdamped situation. For the same conditions

the self-excited vibration is more easily to occur in low nodal diameters vibration mode.