摘要：
W-Ni-Fe-Hf series alloy with different Hf contents were prepared through liquid phase sintering. Influences of Hf on mechanical properties, shielding effect and microstructure of W-Ni-Fe-Hf alloy are analyzed and discussed by using SEM, XRD device, metalloscope, BH1326 gamma-ray shield tester and so on. The results of the study show that adding the microelement Hf could increase dispersity of powder effectively. Hf distributes in the binding phase ofW-Ni-Fe-Hf series alloy (percentage) as an intermediate phase. This intermediate phase not only could refine crystals, but also has good affinity to the microelement Hf, thus enabling to improve mechanical properties and shielding effect of the alloy. However, the intermediate phase formed by excessive Hf is easy to cause segregation on the interface between W crystal boundaries and Ni-Fe binding phase, which would weaken interface binding strength and thereby deteriorate mechanical properties of the alloy. (C) 2017 Elsevier B.V. All rights reserved.
关键词：
Bulk temperature field;convective heat transfer coefficient;friction heat flux;influence factors;influence mechanism
摘要：
The convective heat transfer coefficient of different tooth surfaces and the friction heat flux were identified based on the theory of tribology, heat transfer, and gear meshing theory. A more accurate parametric model of finite element thermal analysis of a single tooth was established by using APDL and the more accurate bulk temperature field of the gear was obtained. The factors that affect the bulk temperature field of gears were also analyzed, and the influence mechanism of each factor was carried out. The results show that high-pressure angle and tooth profile modification cannot only effectively reduce the bulk temperature of the gear, but also benefits the distribution of the bulk temperature. Long-addendum gear is beneficial to the distribution of the bulk temperature. The bulk temperature is proportional to the initial temperature of the lubricating oil. The variations of the equivalent curvature radius, the stiffness and the load sharing ratio of the meshing point are the ultimate cause of the change of the bulk temperature. The results of this paper can provide a more accurate and practical method for obtaining the bulk temperature of the gear, and it also can provide a theoretical basis and method to improve the thermal behavior of gears.
会议名称：
International Conference on Fluid Mechanics and Industrial Applications (FMIA)
会议时间：
OCT 21-22, 2017
会议地点：
Taiyuan, PEOPLES R CHINA
会议主办单位：
[Deng, Jian;Lei, Zeyong;Zhong, Lin] Nan Hua Univ, Sch Mech Engn, Hengyang, Peoples R China.
会议论文集名称：
Journal of Physics Conference Series
摘要：
Uranium hydrometallurgy fixed bed is used to separate and extracting uranium compounds from the leaching of uranium ore. It is a very important equipment in the process of uranium purification. The distribution of the internal flow field of uranium hydrometallurgy fixed bed has great effect on the running efficiency of fixed bed. In this paper, on the basis of fluid mechanics, computational fluid dynamics software Fluent is used to numerical simulation for resin adsorption process in axial flow uranium hydrometallurgy, fixed bed that the diameter is 1600 mm and the height is 6800 mm and to research internal flow field distribution of the fixed bed. The results shows that the fluid distribution in the fixed bed is uneven in the process of adsorbent resin adsorption. The groove shunt filter plate at the exit is a powerful measure to realize the uniform distribution of fluid in the resin layer of fixed bed.
摘要：
Frequency response and their sensitivities analysis are of fundamental importance. Due to the fact that the mode truncation errors of frequency response functions (FRFs) are introduced for two times, the errors of frequency response sensitivities may be larger than other dynamic analysis. Many modal correction approaches (such as modal acceleration methods, dynamic correction methods, force derivation methods and accurate modal superposition methods) have been presented to eliminate the modal-truncation error. However, these approaches are just suitable to the case of un-damped or classically damped systems. The state-space equation based approaches can extend these approaches to non-classically damped systems, but it may be not only computationally expensive, but also lack physical insight provided by the superposition of the complex modes of the equation of motion with original space. This paper is aimed at dealing with the lower-higher-modal truncation problem of harmonic frequency response sensitivity of non-classically damped systems. Based on the Neumann expansion and the frequency shifting technique, the contribution of the truncated lower and higher modes to the harmonic frequency response sensitivity is explicitly expressed only by the available middle modes and system matrices. An extended hybrid expansion method (EHEM) is then proposed by expressing harmonic frequency response sensitivity as the explicit expression of the middle modes and system matrices. The EHEM maintains original-space without having to involve the state-space equation of motion such that it is efficient in computational effort and storage capacity. Finally, a rail specimen is used to illustrate the effectiveness of the proposed method. (C) 2016 Elsevier Ltd. All rights reserved.
作者机构：
[De Weng Tang; Zhi Feng He; Cong Peng; Xi Jian Lv] Cooperative Innovation Center for Nuclear Fuel Cycle Technology and Equipment, Hengyang, Hunan, 421001, China;[De Weng Tang; Zhi Feng He; Cong Peng; Xi Jian Lv] School of Mechanical Engineering, University of South China, Hengyang, Hunan, 421001, China
作者机构：
[陈明慧; 朱红梅; 王新林] School of Mechanical Engineering, University of South China, Hengyang;Hunan;421001, China;[陈明慧; 朱红梅; 王新林] Hunan;[陈明慧; 朱红梅; 王新林] 421001, China
通讯机构：
[Zhu, H.-M.] S;School of Mechanical Engineering, University of South China, Hengyang, Hunan, China
摘要：
The geometric shape of magnets was modified to improve surface planarity and polishing efficiency in magnetorheological planarization. Two modified permanent magnetic yokes and a magnetic brick were used as excitation units of magnetic field. Stress analysis indicated that the polishing stress of the horizontal magnetic yoke was smaller than that of the brick magnet, but greater than that of the sloping yoke. The performances of MR planarizations, including removal rate, roughness, and planarity, of the three magnetic sources were also compared. The results showed that the sloping yoke produced the lowest surface finish of 0.6 nm in R
a
and the best planarity of 0.7 μm in PV, and the brick magnet provided the highest removal efficiency.
作者机构：
[方伟; 唐潇; 衣小龙; 王玉鹏; 杨东军] Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033, China;[唐潇] School of Mechanical Engineering, University of South China, Hengyang, 421001, China;[唐潇] University of Chinese Academy of Sciences, Beijing, 100049, China
通讯机构：
[Wei Fang] C;Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, China
关键词：
SIAR
摘要：
We experimentally evaluate and optimize the time constant of solar irradiance absolute radiometer（SIAR）. The systemic error introduced by variable time constant is studied by a finite element method. The results shown that, with a classic time constant of 30 s for SIAR, the systemic errors are 0.06% in the midday and 0.275% in the morning and afternoon. The uncertainty level which can be considered negligible for SIAR is also investigated, and it is suggested that the uncertainty level has to be less than 0.02%. Then, combining the requirement of international comparison with these two conclusions, we conclude that the suitable time constant for SIAR is 20 s.
作者机构：
[柏兴旺] School of Mechanical Engineering, University of South China, Hengyang, China;[王桂兰] School of Material Science and Engineering, Huazhong University of Science and Technology, Wuhan, China;[张海鸥; 周祥曼] School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
通讯机构：
School of Mechanical Engineering, University of South China, Hengyang, China
期刊：
Journal of Materials Science,2016年51(14):6735-6749 ISSN：0022-2461
通讯作者：
Zhang, Haiou
作者机构：
[Zhang, Haiou; Zhou, Xiangman] Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.;[Zhao, Jingyi; Wang, Guilan; Fu, Youheng] Huazhong Univ Sci & Technol, State Key Lab Mat Proc & Die & Mould Technol, Wuhan 430074, Peoples R China.;[Bai, Xingwang] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Zhang, Haiou] H;Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
关键词：
Solid Fraction;Cellular Automaton;Weld Bead;Rolling Reduction;Cellular Automaton Model
摘要：
Hybrid deposition and micro-rolling (HDMR) is a metal additive manufacturing process that integrates arc direct deposition manufacturing and micro-rolling. A two-dimensional cellular automata and finite volume method coupling model is developed for simulating the microstructure evolution of solidification and the dynamic recrystallization during HDMR forming. The influences of different rolling reductions on dynamic recrystallization fraction, average equivalent radius of recrystallized grains, and the area of dynamic recrystallization region are discussed. The results show that solidification microstructure consists of complete columnar dendrite. The rolling reduction plays a dominant role in determining the area of dynamic recrystallization region and the size of recrystallized grains. The average recrystallized grain size at the top position is not affected by rolling reduction, while the influence of rolling reduction on the dynamic recrystallization fraction and average radius of recrystallized grain is found to be stable, but not linear. The same qualitative and quantitative conclusions are drawn from the experimental results as well.
期刊：
International Journal of Heat and Mass Transfer,2016年103:521-537 ISSN：0017-9310
通讯作者：
Zhang, Haiou
作者机构：
[Zhang, Haiou; Zhou, Xiangman] Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.;[Wang, Guilan] Huazhong Univ Sci & Technol, State Key Lab Mat Proc & Die & Mould Technol, Wuhan 430074, Peoples R China.;[Bai, Xingwang] Univ South China, Sch Mech Engn, Hengyang 421001, Peoples R China.
通讯机构：
[Zhang, Haiou] H;Huazhong Univ Sci & Technol, State Key Lab Digital Mfg Equipment & Technol, Wuhan 430074, Peoples R China.
关键词：
Arc welding based additive manufacturing;Arc;Metal transport;Numerical simulation
摘要：
In arc welding based additive manufacturing, the surface topographies of deposited layer are more complex than conventional welding, therefore, the distribution of the electromagnetic force in molten pool, arc pressure, plasma shear stress and heat flux on molten pool surface are not the same as the conventional welding. A three-dimensional weak coupling modeling method of the arc and metal transport is developed to simulate the arc, molten pool dynamic and droplet impingement in arc welding based additive manufacturing. In the arc model, the molten pool is simplified to be solid state on the basis of experimentally observed results. The arc is simulated firstly, and then the electromagnetic force, arc pressure, plasma shear stress and heat flux are extracted and transmitted to metal transport model. The volume of fluid (VOF) method is employed to track free surface of molten pool and droplet, and the continuum surface force (CSF) method is applied to transform all the surface forces on free surface as localized body forces. This weak coupling model has better accuracy than empirical model and decreases computational consumption. The molten pool morphology and cross-sectional profile of simulated results accord well with experimental results in both single-bead deposition and overlapping deposition, which indicates that this weak coupling modeling method is capable of simulating the complex heat and mass transfer phenomena in arc welding based additive manufacturing. (C) 2016 Elsevier Ltd. All rights reserved.
作者机构：
[张海鸥; 柏兴旺] School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, China;[王桂兰] School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan, China;[柏兴旺] School of Mechanical Engineering, University of South China, Hengyang, China
通讯机构：
[Zhang, H.] S;School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan, China
