Prediction on self-excited vibration of thin spur gear based on energy method

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.