Taking the gear bearing transmission system as the research object, the dynamic model of the gear rolling bearing system with 36 degrees of freedom is established by using the lumped parameter method. The frequency domain diagram of vibration signals of different composite faults of gear and bearing is obtained by simulation, and the vibration characteristics of gear and rolling bearing composite fault are analyzed
(1) By comparing the time domain diagrams of the vibration signals of the driving wheel in different system models, it is found that the time-domain parameters can judge whether there is a fault in the system, but it is impossible to determine the fault type and fault location. It is necessary to further analyze the frequency spectrum of the vibration signal of the fault system.
(2) When gear fault and rolling bearing single fault occur at the same time, it will affect the vibration response of the system. The characteristic frequency of these faults can be easily found in the frequency domain diagram. When the gear fault is combined with the bearing outer raceway fault, the gear fault characteristic frequency in the spectrum diagram and the rolling bearing outer raceway fault characteristic frequency are more obvious; when the gear fault and the bearing inner raceway fault compound, the gear fault characteristic frequency and the bearing inner raceway characteristic frequency in the frequency spectrum diagram are more obvious, the gear fault characteristic frequency amplitude is bigger; the gear fault and the bearing rolling fault characteristic frequency are obvious The characteristic frequency of gear fault is obvious when the moving body fault is compound, and the amplitude of characteristic frequency of rolling bearing inner raceway fault is very small, which is difficult to be found.
(3) The fault frequency of the composite gear system is more complex than that of the composite gear system. When gear fault and bearing inner and outer raceway faults are combined, the characteristic frequency of several faults is obvious, and the amplitude of gear fault characteristic frequency is the largest. When gear fault, bearing rolling element fault and outer raceway fault are combined, the characteristic frequency of bearing rolling element fault is very weak, and the characteristic frequency and its multiple frequency of outer raceway fault are obvious. When gear fault, bearing rolling element fault and inner raceway fault are combined, the characteristic frequency of inner raceway fault and gear fault is obvious, and the sideband with interval of rotor frequency appears around the characteristic frequency of inner raceway fault. Similarly, the characteristic frequency of rolling element fault is not easy to be found. When gear fault, bearing inner raceway fault, outer raceway fault and rolling element fault occur at the same time, the characteristic frequency amplitude of gear fault is the largest, followed by the inner raceway fault, and then the outer raceway fault. It is difficult to find the characteristic frequency of rolling element fault.