Abstract
Tooth fractures and cracks are common defects in gear transmission systems. Crack propagation paths of the spur gears are acquired using the fracture mechanics theory. Based on the simulated crack propagation path, the flexible body model of the cracked gear system is established in multibody dynamic software ADAMS. The vibration signals of cracked gear under different torques obtained from the simulation are verified by the experimental results. Some statistical indictors (root mean square and Kurtosis) are used to quantify the damage degree. In addition, the fault features of the gear system under crack and tooth fracture faults are analyzed by utilizing the instantaneous energy. The results indicate that the amplitude of the harmonics of the meshing frequency and the sideband frequencies increase gradually with the increase of torques and crack lengths. Especially, for the tooth fracture fault, its influence on Kurtosis value is particularly obvious. Meanwhile, according to the instantaneous energy, the tooth fracture fault will result in severe energy impacts and cause a sharp increase in the vibration amplitude.
Highlights
Gear transmission system, including gears, bearings, shafts, and gearbox casing, is a complex dynamic system
The vibration signals of cracked gear systems under different torques, crack lengths, and tooth fracture fault are measured by acceleration sensors (see Figure 5(b))
According to the change of instantaneous energy, the energy impact caused by crack fault and tooth fracture fault is obvious, which provides an effective method for the fault diagnosis of gear pair under tooth fracture fault
Summary
Gear transmission system, including gears, bearings, shafts, and gearbox casing, is a complex dynamic system. Ma et al.[8,9,10] calculated the time-varying mesh stiffness of spur gear under different crack lengths using the potential energy method and the finite element method, and the mesh stiffness was imported into the dynamic model to analyze the dynamic response. Fernandez del Rincon et al.[27] presented an analytical-finite element method to analyze the effects of torque and crack lengths on load sharing ratio, transmission error, and mesh stiffness. Jia et al.[34] established a gear dynamic model with 26 degrees of freedom, including three shafts and two spur gear pairs, and compared the vibration signals of the gear tooth with crack and spalling. Based on the simulation model and experimental method, this paper compares the signal features on time-domain and frequency-domain under crack and tooth fracture faults.
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