Simulation method and spectrum modulation characteristic analysis of typical fault signals of inter-shaft bearing

In order to study the frequency spectrum characteristics of the vibration signal of the inter-shaft bearing defect fault in the aero-engine dual-rotor system, a vibration signal mathematical model is established based on the fault characteristic frequency of the inner and outer ring defects of the inter-shaft bearing, and the mutual modulation law of the signals during transmission is analyzed. A test bench for signal transmission path analysis is built to verify the calculation results. The results indicate that the fault signal of the inter-shaft bearing defect significantly attenuates during transmission, and the characteristic frequency of the inter-shaft bearing fault is modulated with the rotor rotation frequency. There are corresponding characteristic frequencies and modulation frequency components in the envelope spectrum of the inter-shaft bearing. The error between the experimental and simulation results is less than 1%, which verifies the accuracy of the simulation calculation results. After being transmitted to the rotor through the inter-shaft bearing, the rotor frequency includes the modulation frequency of bearing varying compliance frequency and rotation frequency, as well as the fault characteristic frequency of the inter-shaft bearing.