In view of the problem of outer ring fatigue peeling fault diagnosis of intermediate bearing in a typical double-rotor aero-engine

based on the vibration coupling dynamic model of aero-engine

the early peeling fault model of outer ring of intermediate bearing was introduced

and the vibration response of aero-engine was obtained by numerical integration. The fault features of intermediate bearing with peeling off on outer ring were extracted and analyzed. It was found from the signal analysis that: (1) there were 4 times of the characteristic frequency of outer ring fault and the modulation sidebands with the outer ring rotation frequency taken as the interval on both sides. (2) With the increase of unbalance

the characteristic frequency component was basically unchanged

and the sidebands became more prominent. (3) With the increase of bearing clearance

the impact caused by outer ring fault was more intense

and the characteristic frequency and modulation sideband frequency were significantly increased. By comparing the fault characteristics of the signals from the bearing housing to the casing

the results showed that the impact caused by the early fatigue peeling of the intermediate bearing transmitted to the casing from the bearing housing could produce a great degree of attenuation

and the bearing fault characteristics basically disappeared in the casing measurement point signals.