A series of research work is carried out on the influence of typical faults such as root crack and bearing local fault on the vibration characteristics of gear transmission system, including the influence of different root crack faults on the dynamic characteristics of gear pair, the influence of rolling bearing with different faults on the dynamic vibration response of bearing system, and the influence of compound fault of gear and bearing on the vibration characteristics of gear transmission system However, there are still many problems to be further studied and developed
1) The actual root crack propagation path is more complex, and its path is not a simple straight line. Therefore, in the future research, it is necessary to establish a crack propagation path model closer to the real situation, so as to improve the calculation accuracy of the comprehensive meshing stiffness of the gear with root crack fault.
2) The lumped mass method is used to simplify the dynamic model of gear transmission system, which ignores the influence of many factors on the dynamic model of gear transmission system, such as tooth side clearance, tooth surface friction and gear geometric eccentricity. At the same time, the transmission shaft is regarded as rigid, which will affect the accuracy of the whole model, so it needs to be more accurate and more accurate Comprehensive simulation model to simulate the gear transmission system.
3) In the research of fault excitation of rolling bearing, the influence of manufacturing error of rolling element and inner and outer raceway on system vibration response is not considered. The bearing fault is simplified as square pit, which does not necessarily conform to the actual bearing fault shape. At the same time, the relative sliding between rolling element and inner and outer raceway, centrifugal force of rolling element and the effect of cage on rolling element are ignored And so on.
4) In the frequency domain analysis of the system, there are many frequency components that can not determine the source, and the characteristic frequency of some faults is difficult to find, which will affect the accurate identification and diagnosis of faults, and bring certain impact. Therefore, the research on these faults should be strengthened to obtain clear fault characteristic frequency and improve the accuracy of fault diagnosis.