Planetary gear systems have been widely used in transportation, construction, metallurgy, petroleum, aviation and other industrial fields. Under the same condition of power transmission, they have a more compact struc...Planetary gear systems have been widely used in transportation, construction, metallurgy, petroleum, aviation and other industrial fields. Under the same condition of power transmission, they have a more compact structure than ordinary gear train. However, some critical parts, such as sun gear, planet gear and ring gear often suffer from fatigue and wear under the conditions of high speed and heavy load. For reliability research, in order to predict the fatigue probability life of planetary gear system, detailed kinematic and mechanical analysis for a planetary gear system is firstly completed. Meanwhile, a gear bending fatigue test is carried out at a stress level to obtain the strength information of specific gears. Then, a life distribution transformation model is established according to the order statistics theory. Transformation process is that, the life distribution of test gear is transformed to that of single tooth, and then the life distribution of single tooth can be effectively transformed to that of the planetary gear system. In addition, the effectiveness of the transformation model is finally verified by a processing method with random censoring data.展开更多
We report the creation of the first mixture of ^6Li and ^88Sr atoms in an optical dipole trap. Using this mixture,a measurement of the interspecies thermalization process is carried out and the previously unknown inte...We report the creation of the first mixture of ^6Li and ^88Sr atoms in an optical dipole trap. Using this mixture,a measurement of the interspecies thermalization process is carried out and the previously unknown interspecies s-wave scattering length between ^6Li and ^88Sr atoms is extracted to be |a6 Li-88 Sr|=(380-100^+160)a0 with a0 being the Bohr radius from the rate of interspecies thermalization.展开更多
In our previous report[Chin.Phys.Lett.36(2019)073401],the angular trap frequencies cji and 5 in Eq.(2)were wrongly substituted with trap frequencies(without 2π)at the computation stage.This results in underestimation...In our previous report[Chin.Phys.Lett.36(2019)073401],the angular trap frequencies cji and 5 in Eq.(2)were wrongly substituted with trap frequencies(without 2π)at the computation stage.This results in underestimation of the atom densities and thereby overestimation of the s-wave scatteting length between 6Li and 88Sr atoms.展开更多
Abstract A friction stir processing-based method was used to repair cracks in the 2024 aluminum alloy plates. The temperature field and plastic material flow pattern were analyzed on the basis of experimental and fini...Abstract A friction stir processing-based method was used to repair cracks in the 2024 aluminum alloy plates. The temperature field and plastic material flow pattern were analyzed on the basis of experimental and finite element simulation results. Microstructure and tensile properties of the repaired specimens were studied. The results showed that the entire crack repairing was a solid-phase process and plastic materials tended to flow toward the shoulder center and then resulted in the repairing of cracks. Meanwhile, the coarse grain structures were refined in repaired zone （RZ）, while the grains in thermal-mechanically affected zone and heat-affected zone were elongated and driven to grow up. Meanwhile, large phases are crushed into small particles and dispersed inside the RZ. Finally, the strength of the repaired specimens can be restored dramatically and their ductility can be partially restored. After heat treatment, the tensile properties of the repaired specimens can be further enhanced.展开更多
基金Supported by National Key Technology Research and Development Program of China(Grant No.2014BAF08B01)Natural Science Foundation of China(Grant No.51335003)Collaborative Innovation Center of Major Machine Manufacturing in Liaoning Province of China
文摘Planetary gear systems have been widely used in transportation, construction, metallurgy, petroleum, aviation and other industrial fields. Under the same condition of power transmission, they have a more compact structure than ordinary gear train. However, some critical parts, such as sun gear, planet gear and ring gear often suffer from fatigue and wear under the conditions of high speed and heavy load. For reliability research, in order to predict the fatigue probability life of planetary gear system, detailed kinematic and mechanical analysis for a planetary gear system is firstly completed. Meanwhile, a gear bending fatigue test is carried out at a stress level to obtain the strength information of specific gears. Then, a life distribution transformation model is established according to the order statistics theory. Transformation process is that, the life distribution of test gear is transformed to that of single tooth, and then the life distribution of single tooth can be effectively transformed to that of the planetary gear system. In addition, the effectiveness of the transformation model is finally verified by a processing method with random censoring data.
基金Supported by the National Key Research and Development Program of China under Grant Nos 2018YFA0306503 and 2018YFA0306504the National Natural Science Foundation of China under Grant Nos 91636213,91736311,11574177,91836302 and 11654001
文摘We report the creation of the first mixture of ^6Li and ^88Sr atoms in an optical dipole trap. Using this mixture,a measurement of the interspecies thermalization process is carried out and the previously unknown interspecies s-wave scattering length between ^6Li and ^88Sr atoms is extracted to be |a6 Li-88 Sr|=(380-100^+160)a0 with a0 being the Bohr radius from the rate of interspecies thermalization.
文摘In our previous report[Chin.Phys.Lett.36(2019)073401],the angular trap frequencies cji and 5 in Eq.(2)were wrongly substituted with trap frequencies(without 2π)at the computation stage.This results in underestimation of the atom densities and thereby overestimation of the s-wave scatteting length between 6Li and 88Sr atoms.
基金supported by the National Natural Science Foundation of China(Grant No.51405309)the Natural Science Foundation of Liaoning Province(Grant No. 2015020183)
文摘Abstract A friction stir processing-based method was used to repair cracks in the 2024 aluminum alloy plates. The temperature field and plastic material flow pattern were analyzed on the basis of experimental and finite element simulation results. Microstructure and tensile properties of the repaired specimens were studied. The results showed that the entire crack repairing was a solid-phase process and plastic materials tended to flow toward the shoulder center and then resulted in the repairing of cracks. Meanwhile, the coarse grain structures were refined in repaired zone （RZ）, while the grains in thermal-mechanically affected zone and heat-affected zone were elongated and driven to grow up. Meanwhile, large phases are crushed into small particles and dispersed inside the RZ. Finally, the strength of the repaired specimens can be restored dramatically and their ductility can be partially restored. After heat treatment, the tensile properties of the repaired specimens can be further enhanced.
