With the all-round development of the mechanical industry, the requirements of the mechanical equipment for the transmission system are higher and higher. Gear transmission system has the advantages of reliable transmission, compact structure and strong bearing capacity, so it is widely used in vehicles, machine tools, air transportation and other mechanical equipment. The most frequent fault in gear transmission system is the tooth fracture caused by the root fatigue crack growth.
The initiation and propagation of root fatigue crack will change the dynamic characteristics of the transmission system, and it is reflected in the abnormal signals such as box surface vibration and shaft torsional vibration. If these abnormal signals can be identified by the targeted algorithm, the fatigue crack state of the internal gear can be understood, so as to realize the monitoring of the gear health. In order to establish this kind of targeted recognition algorithm, it is necessary to study the law of variation between the fatigue crack growth behavior and the vibration signal through the theoretical model.
The theoretical analysis of the dynamic characteristics of the transmission system has always been valued by researchers. Qian Lulu compared the calculation results of the finite element model with the experimental results, which verified the consistency of the natural frequency of the single-stage gear transmission system, and provided the basis for the stability analysis of the gear system. Fan Jun and others simulated the continuous meshing process of gear pair by contact finite element method, and quantitatively analyzed the dynamic response of gear under resonance state. Ma Rui et al. Established a parametric dynamic model, analyzed the vibration characteristics of Cracked Gear signals through amplitude frequency curves, and revealed different bifurcation modes caused by cracks and transmission errors according to the singularity theory. Wang et al. Summarized the influence of time-varying meshing stiffness and backlash on the nonlinear dynamics of gear system. Parey et al. Studied the gear system with defects and analyzed the dynamic characteristics of various gear transmission systems with faults. Howard et al. Established the 16 DOF motion equation of the gear transmission system considering the tooth surface friction, and analyzed the vibration response of the Cracked Gear System by numerical method. Jia et al. Established a dynamic model of three-axis two pair gear with 26 degrees of freedom, and compared the influence of time-varying meshing stiffness and load ratio on local tooth spalling damage and crack failure. Lin Tengjiao et al established the coupling dynamic model of the fault helical gear, studied the impact phenomenon of the vibration response, and analyzed the influence of the gear fault on the frequency response of the gear system. The characteristics and application occasions of various modeling and analysis methods of gear transmission system are different. The appropriate research methods should be determined according to the characteristics of two-stage gear transmission system with crack fault.
ZHY Gear The dynamic model of two-stage transmission system is established, and the time-varying meshing stiffness calculation and fatigue crack growth simulation analysis based on the cantilever principle are embedded in it. The time-varying meshing stiffness change rule caused by the fatigue growth of the tooth root crack and the abnormal change rule of the dynamic response of the gear system with the crack fault are calculated, which can be used for the fault diagnosis and implementation of the gear transmission system Time monitoring provides theoretical support.