Research on fatigue damage of low speed and heavy load gears by foreign scholars

Shi uses the software perdynamic (PD), which is used to analyze the crack propagation in the fracture of engineering materials. Bonding constitutes the constitutive relationship of circumferential dynamics. The broken bond represents the fracture of materials, but it can not be used for fatigue analysis. Based on miner’s linear cumulative damage theory, the PD fatigue failure model of high cycle fatigue is established by combining with the fatigue failure criterion instead of the old failure criterion. Finally, the bending fatigue fracture analysis of standard involute gear is carried out. The results show that the PD fatigue fracture model is consistent with the experiment. The PD fatigue fracture model provides a method for predicting fatigue crack growth and fatigue life.

J. Kramberger thinks that it is necessary to carry out anti fatigue design for mechanical components bearing periodic load, so a numerical model of bending fatigue life of thin ring gear in truck gearbox is proposed. The bending fatigue life of the thin flange spur gear of truck gearbox is studied. It is considered that the service life of gears can be divided into the initial stages of damage accumulation and crack propagation. Finite element method and boundary element method are used to analyze the fatigue life of thin rim gear. The method based on continuum mechanics is used to predict the starting stage of fatigue process, in which the basic fatigue parameters of materials are considered. Linear elastic fracture mechanics is used to evaluate the residual life of gears with initial cracks. The results show that with the decrease of rim thickness, the key position of crack initiation moves to the root area.

Podrug. S et al. Proposed a calculation model for determining the bending fatigue life of gear tooth root. This study determined the influence of moving tooth load on gear fatigue life, and considered the crack closure effect when using numerical simulation and linear elastic fracture mechanics theory to simulate the fatigue crack propagation behavior. It is proved that the critical plane method can not only predict the crack initiation life, but also predict the crack initiation direction, which is a good foundation for further analysis of crack propagation. By considering two kinds of closure mechanisms (roughness and oxide induced crack closure), the predicted crack growth life and crack path of gear root stress are more close to the experimental results than the existing methods.

Rad A. Amiri et al. Used linear elastic fracture mechanics to simulate the fatigue crack growth of helical gear tooth root, and used propagation finite element method to simulate the fatigue crack growth in three-dimensional state and obtain its propagation path. It is proved that the crack tends to propagate to the top of the gear tooth, and the crack propagation path in the plane cuts the initial crack in half, which is similar to the growth path of straight through crack in spur gear.

Agarwal V et al. Proposed a calculation model to study the fatigue crack growth characteristics of gear root in the presence of inclusions. The crack growth path and fatigue life were predicted by linear elastic fracture mechanics and LEFM based finite element model. The results show that for the hard inclusions near the original crack path, the crack growth tends to slow down. The size of inclusions and the proximity of inclusions to the original crack path are significant.

Cur à F et al. Studied the correlation between the thickness of rim and web on the crack propagation path of thin tooth gear, and involved bending failure. The three-dimensional extended finite element method is used for numerical simulation. The results show that the interaction between the web and rim thickness may affect the crack growth and the corresponding safety or catastrophic failure.

According to the actual working conditions of gears, s Renping and others regarded the supporting gear shaft as elastic support. The influence of elastic tooth on gear vibration is considered and studied, and the dynamic response of elastic tooth and gear is analyzed. On this basis, the gear body is regarded as a three-dimensional elastic disk, and the gear tooth is regarded as an elastic cantilever beam. Under the condition of elastic boundary (supporting shaft), the elastic plate and elastic tooth are combined, and the influence of three-dimensional elastic plate on the response of meshing tooth under the condition of elastic boundary is also included. The dynamic model of gear support system and the calculation model of gear tooth response are established. The influence of pitch circle crack on the radiated sound field of gear structure is greater than that of root crack, and the influence of crack position is greater than that of crack depth. For the gear with crack defect, the acoustic radiation characteristics of Cracked Gear and normal gear structure are not the same, and the acoustic radiation characteristics are abnormal and change sharply. It lays a solid and reliable theoretical foundation for using acoustic diagnosis method to study gear fault.

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