Contact Fatigue Life Prediction Of Automobile Bevel Gear Under Spectrum Loading

Gear is an important mechanical foundation,widely used in aviation,aerospace,ships,automobiles,wind power and other equipment fields,is an indispensable and important component of the equipment manufacturing industry,its performance directly determines the performance and reliability of major equipment.With the equipment’s relentless pursuit of power density,bearing capacity and reliability,as well as the emergence of more and more high speed,heavy load and other extreme harsh service environment in aviation,aerospace,wind power,military vehicles and other fields,the problem of gear contact fatigue failure is increasingly prominent.From a global perspective,gear contact fatigue failure is a common occurrence of equipment accidents,making gear contact fatigue become an important bottleneck limiting the performance and reliability of modern gear equipment.The strength design of traditional transmission parts is based on static strength analysis.By the 1970 s,the research and application of fatigue load spectrum had developed rapidly,and the most successful ones were those in automobile,agricultural machinery,aviation,aerospace and navigation.Because the load spectrum plays an important guiding role in the design of products,many industries at home and abroad regard the study of load spectrum as a key confidential research topic in the process of mechanical service.As an important part of the automobile transmission system,the drive axle plays an important role in reducing the speed and increasing the torque,changing the direction of torque transmission,realizing the differential speed and bearing various loads between the road surface and the frame,which is related to the dynamic performance,handling stability and ride safety of the vehicle.Therefore,it is of great significance to study its fatigue durability.In the truck drive axle assembly,the main reducer hypoid gear has large working load and long working time,so it is often the weak link of the drive axle assembly fatigue durability.Therefore,the fatigue life of automobile bevel gear based on load spectrum is studied.A gear contact fatigue life method based on load spectrum is developed.First,using the commercial gear design software MASTA,the accurate geometric model of hypoid gear for automobile is established.Then the finite element model is established,the finite element analysis of automobile bevel gear is carried out,the multi-axis stress-strain state of the bevel gear is obtained,and the contact fatigue life of the bevel gear is predicted by using Brown-Miller-Morrow fatigue criterion.The variation law of fatigue life of tooth surface under different load levels is simulated,and the corresponding S-N curve of contact fatigue is given.In addition,the finite load-time history under typical operating conditions of the drive shaft is used,the load-time history is statistically processed by rain flow method,the two-dimensional load spectrum of multiple operating conditions is compiled by probability density function method,and the program load spectrum is established by goodman average stress equation.According to the S-N curve of contact fatigue and the program load spectrum,the contact fatigue life is predicted by using the law of fatigue damage accumulation.The effects of Miner criterion,corten-dolan damage theory and Manson’s bilinear damage theory on contact fatigue life were discussed.A gear fatigue life prediction method based on load spectrum is developed.And this method is based on matlab GUI to develop a set of software.