Bending fatigue is an essential parameter that needs to be considered in the improvement process of the power density and reliability of gear drives. Quantitative relations among the manufacturing parameters, surface ...Bending fatigue is an essential parameter that needs to be considered in the improvement process of the power density and reliability of gear drives. Quantitative relations among the manufacturing parameters, surface integrities, and fatigue performance are not clear, which seriously limits the effectiveness of an anti-fatigue design. For this work, tooth-bending fatigue tests of carburized gears with different surface integrities were performed using a pulsator. The effects of the manufacturing parameters and surface integrities on the gear fatigue, such as surface hardness and residual stress, were investigated. The experimental results revealed that due to the improvement of surface integrities after shot peening, the nominal bending stress number(fatigue limit) increased by 6.3%–31.1%, with an amplitude range of 39–143 MPa. A supervised learning algorithm of a random forest was implemented to determine the contribution of the surface hardness and surface residual stress to the nominal stress number. An empirical formula was proposed to predict the nominal stress number considering the surface integrities. The prediction error was less than 7.53%, as verified by several gear-bending fatigue tests. This provided theoretical support for the modern, anti-fatigue design of the gears.展开更多
A mathematical model for system life and reliability of a multiple power takeoffs aeroengine accessory gearbox transmission is presented.The geometry model of gear train is distributed into several subsystems by diffe...A mathematical model for system life and reliability of a multiple power takeoffs aeroengine accessory gearbox transmission is presented.The geometry model of gear train is distributed into several subsystems by different transmitted powers.The lives of each component are combined to determine the units,subsystems and entire system lives sequentially according to a strict series probability model.The unit and subsystem interface models are defined to dispose the loads of common components.The algorithm verification is presented and a numerical example is given to illustrate the use of this program.The initial design could not fulfill the life requirement.A design modification shows that the gear train has a more balanced life distribution by strengthening the weak parts,and the overall life of entire system is increased above the design requirement.This program can help the designer to approach an optimal accessory gearbox transmission design efficiently.展开更多
基金supported by the National Key R&D Program (Grant No.2020YFB2008200)the National Science and Technology Major Project(Grant No. 2019-VII-0017-0158)。
文摘Bending fatigue is an essential parameter that needs to be considered in the improvement process of the power density and reliability of gear drives. Quantitative relations among the manufacturing parameters, surface integrities, and fatigue performance are not clear, which seriously limits the effectiveness of an anti-fatigue design. For this work, tooth-bending fatigue tests of carburized gears with different surface integrities were performed using a pulsator. The effects of the manufacturing parameters and surface integrities on the gear fatigue, such as surface hardness and residual stress, were investigated. The experimental results revealed that due to the improvement of surface integrities after shot peening, the nominal bending stress number(fatigue limit) increased by 6.3%–31.1%, with an amplitude range of 39–143 MPa. A supervised learning algorithm of a random forest was implemented to determine the contribution of the surface hardness and surface residual stress to the nominal stress number. An empirical formula was proposed to predict the nominal stress number considering the surface integrities. The prediction error was less than 7.53%, as verified by several gear-bending fatigue tests. This provided theoretical support for the modern, anti-fatigue design of the gears.
文摘A mathematical model for system life and reliability of a multiple power takeoffs aeroengine accessory gearbox transmission is presented.The geometry model of gear train is distributed into several subsystems by different transmitted powers.The lives of each component are combined to determine the units,subsystems and entire system lives sequentially according to a strict series probability model.The unit and subsystem interface models are defined to dispose the loads of common components.The algorithm verification is presented and a numerical example is given to illustrate the use of this program.The initial design could not fulfill the life requirement.A design modification shows that the gear train has a more balanced life distribution by strengthening the weak parts,and the overall life of entire system is increased above the design requirement.This program can help the designer to approach an optimal accessory gearbox transmission design efficiently.
