Research trend of root crack of spur gear

The research of fatigue crack is a part of reliability research. In engineering application, it is mainly to predict the fatigue life of spur gears. The prediction of fatigue life can not only guide the design of gear teeth, but also prevent accidents caused by fatigue fracture. According to the fatigue crack propagation process, the fatigue failure of spur gear tooth root can be roughly divided into three basic processes: the first is the crack initiation stage, and a micro crack occurs at a certain position of tooth root after several cycles of load cycle; The second is the stable crack propagation stage, which gradually expands from micro crack to macro crack; Finally, the instability expands, and the spur gear fails. The research of fatigue life is mainly to estimate the crack initiation life and crack propagation life, so scholars mainly focus on the first and second stages of fatigue crack. There are many factors affecting crack initiation life, such as some parameters of spur gear itself: modulus, tooth thickness and surface roughness; Among these factors, surface roughness has a great influence on crack initiation. The greater the surface roughness, the more obvious the stress concentration on the tooth surface, and the easier it is to produce cracks. In addition, the influence of working environment on crack initiation is also very important, such as high temperature, corrosion, etc. Paris formula is generally used for life estimation in crack propagation stage. In this stage, the effects of stress level, temperature and spur gear parameters are mainly considered.

To sum up, in the future, various influencing factors in practice need to be considered in the research of spur gear tooth root fatigue crack. With the development of mechanics and computer simulation technology, the research of fatigue crack under complex working conditions and environment will be further developed, which will provide a solid foundation for mechanical system reliability and product life-cycle management.

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