Calculation and analysis of stress intensity factor and J-integral of helical gear crack

Gear is of great significance to all kinds of mechanical equipment. Its performance may directly affect the service life and reliability of the equipment. Gear fatigue fracture is one of the main causes of mechanical equipment failure. Fracture mechanics is the basis of studying the crack of helical gear. Combining the change law of stress intensity factor and J-integral, we can better study and explore the fatigue fracture life and the crack initiation and cracking of parts.

In recent years, some important achievements have been made in the research of stress intensity factors at home and abroad. Based on the conventional extended finite element method, Wen Longfei solved the problem of linear correlation and high ill conditioned global stiffness matrix in the conventional method, greatly improved the solution efficiency, and solved the problems of numerical oscillation and low accuracy in solving the dynamic stress intensity factor. Sun Zhijia and others analyzed the influence of initial cracks with different parameters on the fatigue life of gears and simulated the crack propagation path at the tooth root by using the finite element method. Wan Zhiguo et al. Calculated the stress intensity factor of the front edge of the two-dimensional root crack with the initial crack by using the finite element software, and calculated the propagation angle after the instability of the crack, and simulated the two-dimensional root crack propagation path.

Liu Xinbo et al. Used the finite element software to simulate the influence of different initial two-dimensional cracks on the crack growth path and life. The experiment verified that the error between the simulation prediction and the experimental results is small, which can meet the needs of practical engineering. Extended finite element method (XFEM) is a new numerical method. The main advantage of XFEM is that in the process of crack propagation, only the propagation path is needed to express, and there is no need to divide the mesh repeatedly. Therefore, this method is very effective for simulating the fatigue crack propagation of mechanical parts. Based on the theory of fracture mechanics, Xiao Junfeng et al. Studied the residual fatigue life of root crack of wind turbine gear under different wind loads. Zhao Guoping et al. Analyzed the influence of friction dynamic characteristics on the whole life of crack initiation and propagation of helical gears under mixed lubrication.

It can be seen from the above research that many scholars have made a lot of contributions to the research of two-dimensional cracks in different mechanical parts, and the research in this area has been relatively mature. Now, many scholars begin to study mechanical parts with initial three-dimensional cracks, such as static stress intensity factor, dynamic stress intensity factor, crack propagation path and crack fatigue life prediction. Although a lot of research has been done on the direction of stress intensity factor of three-dimensional solid crack, the stress intensity factor will be different for different structures of solid components. The feature is to analyze and calculate the three-dimensional helical gear model with initial crack by finite element software, so as to obtain the inherent law of stress intensity factor and J-integra.

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