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Theoretical and experimental research on static stiffness,performance,and lift-off characteristics of multi-layer gas foil thrust bearings

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Friction 2024年第11期12卷 2458-2479页

作者： Yang HU Pengjing DING Fangling WU Xiaojing WANG Bo LIANG Yonggang MENG School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200072China Aviation Key Laboratory of Science and Technology on Aero Electromechanical System Integration Nanjing Engineering Institute of Aircraft SystemsNanjing 211106China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

In this study,a new comprehensive fully coupled elastic–hydrodynamic model is developed for a multi-layer gas foil thrust bearing(GFTB).The interaction effects among the top foil,back board,middle foil,and bottom foil,as well as the Coulomb friction effect,are *** stiffness and static characteristics obtained by the experimental and theoretical approaches are in good agreement,which verifies the accuracy of the *** contribution of each foil layer to the overall stiffness and the load-carrying mechanism are *** effects of the load,preload,and rotational speed on the static performance are investigated ***,start–stop tests are performed to achieve the lift-off speed,start-up torque,and shut-down torque under various operating conditions.

关键词： multi-layer gas foil thrust bearing(GFTB) load carrying mechanism static performance

A NOVEL multi-layer SPRAY DEPOSITION TECHNOLOGY

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中国有色金属学会会刊：英文版 1995年第4期5卷 73-78页

作者： Chen Zhenhua Huang Peiyun Jiang Xiangyang Wang Yun Peng Chaoqun(Research institute of Non-Equilibrium Materials Science and Engineering,Central South University of Technofogy,Changsha 410083) Central South Univ of Technology Changsha China

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关键词： multi-layer spray deposition Al-Fe-V-Si alloy

Damage of multi-layer spaced metallic target plates impacted by radial layered PELE

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Defence Technology（防务技术） 2020年第1期16卷 201-207页

作者： Chun Cheng Zhong-hua Du Xi Chen Li-zhi Xu Cheng-xin Du Ji-long Han Xiao-dong Wang School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing210094China

Three different kinds of PELE(the penetrator with lateral efficiency) were launched by ballistic artillery to impact the multi-layer spaced metal target *** lmpact velocities of the projectiles were measured by the velocity measuring *** damage degree and process of each laye r of target plate impacted by the three kinds of projectiles were *** experimental results show that all the three kinds of projectiles have the effect of expanding holes on the multi-layer spaced metal target *** the normal structure PELE(without layered) with tungsten alloy jacket and the radial layered PELE with tungsten alloy jacket,the diameters of holes on the seco nd layer of plates are 3.36 times and 3.76 times of the diameter of the projectile,re *** radial layered PELE with W/Zr-based amorphous composite jacket,due to the large number of tungsten wires dispersed after the impact,the diameter of the holes on the four-layer spaced plates can reach 2.4 times,3.04 times,5.36 times and 2.68 times of the diameter of the ***,the normal structure PELE with tungsten alloy jacket and the radial layered PELE whit tungsten alloy jacket formed a large number of fragments impact marks on the third target *** the number of fragments penetrating the third target plate is not as large as that of the normal structure PELE,the area of dispersion of fragments impact craters on the third target plate is larger by the radial layered *** radial layered PELE with W/Zr-based amorphous composite jacket released a lot of heat energy due to the impact of the matrix material,and formed a large area of ablation marks on the last three target plates.

关键词： PELE(the penetrator with lateral efficiency) multi-layer spaced metal target plates Impact Damage

Thixoforming of 6066 aluminum alloy by multi-layer spray deposition

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中国有色金属学会会刊：英文版 2001年第1期11卷 108-114页

作者：陈振华张豪康智涛 Cent S Univ Non Equilibrium Mat Res Inst Changsha 410083 Peoples R China

Two thixoforming technologies of 6066 aluminum alloy (Al 1.37Si 1.37Mg 0.77Cu 0.07Mn ) produced by multi layer spray deposition process were studied. The spray formed materials are of equiaxed and very fine grain (10～20 μm). And the grain size coarsens slower than that of conventional casting materials at temperature below the liquidus, which may relate to high temperature particles distributed along the grain boundaries. Extrusion and hot pressing were used as the thixoforming processes respectively. After extrusion the materials show a microstructure of mean grain size below 20 μm without obvious recrystallization. The mechanical properties achieved via extrusion and pressing in semi solid state attain that of common wrought materials with shorter peak aging time of 4～5 h, about half of that in conventional condition. [

关键词： thixoforming multi-layer spray deposition 6066 aluminum alloy

Preparation of large size aluminium alloy cylindrical preforms by multi-layer spray deposition

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中国有色金属学会会刊：英文版 2000年第2期10卷 196-199页

作者：康智涛袁武华陈振华周多三 Cent S Univ Technol Non Equilibrium Mat Res Inst Changsha 410083 Peoples R China

Preparation of large scale aluminium alloy cylindrical preforms have been studied by the methods of vertical spray deposition and tilted spray deposition respectively. The results show that aluminium alloy cylindrical preforms of a size up to d 320 mm×500 mm can take shape well by applying multi layer tilted spray deposition technology if the process is controlled properly. The spray system scans in a radius ranging from the center to the rim of the preform, and the velocity is inversely proportional to the displacement. The multi layer deposited preforms exhibit high cooling rate. The larger the diameter is and the higher the cooling rate and yield are.

关键词： multi-layer spray deposition vertical spray tilted spray

Characterization of multi-layer Weld Metal and Creep–Rupture Behavior of Modified 10Cr–1Mo Welded Joint

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Acta Metallurgica Sinica(English Letters) 2020年第6期33卷 808-820页

作者： Chang-Zhen Zhang Chen-Dong Shao Hai-Chao Cui Hua-Li Xu Feng-Gui Lu Shanghai Key Laboratory of Materials Laser Processing and Modification School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The rupture behavior of the modified 10Cr–1Mo steel multi-layer welded joint is determined by the fine-grain zones of the weld metal adjacent to the fusion line during the long-term creep test at 620℃. The microstructures of multi-layer weld metal before and after the creep tests were characterized in detail, and its role in creep behavior was systematically investigated. Most grain boundaries of subgrains represented the low-angle boundaries in the weld metal adjacent to the fusion line both before and after the creep test. The widths of grains in the fine-grain zones were about 0.5–1 μm. The fracture morphology appeared as "wave" structure due to the cracking initiating from multi-layer grain boundaries in the fine-grain zones. Some W elements that melted into weld metal adjacent to the fusion line altered the thermodynamic and kinetic conditions of the Laves phase formation during long-term creep exposure. Laves phase particles mainly distributed along the grain boundaries due to the faster diffusion and segregation of Mo, W, and Si elements. Moreover, higher-density grain boundaries in the fine-grain zones led to easier nucleation and growth of Laves phase particles. Compared with other areas in the welded joint, the size of Laves phase particles in the fine-grain zones of the weld metal adjacent to the fusion line was the largest ones. The interface between Laves phase particles and the matrix acted as the nucleation site of creep micro-cavities. The creep micro-cavities grew up at the expense of fine-grain boundaries and even grew across the grain boundary deeply into adjacent grains, and then developed to cracks in the fine-grain zones.

关键词： 10Cr–1Mo Welded joint Fine grains multi-layer Creep rupture

Parameter Survey of Thermally Highly Loaded,Porous and Cooled multi-layer Systems for Turbine Blades

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Journal of Thermal Science 2007年第2期16卷 181-185页

作者： Peng Shan Dieter Bohn Jing Ren N.Surken Department of Jet Propulsion Beijing University of Aeronautics & AstronauticsBeijing 100083China Institute of Steam and Gas Turbines RWTH Aachen52056 AachenGermany

This study is an advanced investigation for the cooling of high temperature turbine vanes and blades. The efficient heat exchanging near the surface of a blade may be achieved by forcing a cooling air flow emitting out of a thin layer of the porous metal which is pasted on the structural high strength metal. The contents include the consideration on the computational model of heat transfer through a layer of porous material, the concrete modeling and the analysis of the model, the numerical survey of key parameters for both the two-layer porous materials and the heat transfer fluid flow passing through the model channels. The results revealed that the constructed system is reasonable. Proposed an evaluation formula for the porous material heat transfer efficiency.

关键词： heat transfer thermally highly loaded porous multi-layer

Efficient Training of multi-layer Neural Networks to Achieve Faster Validation

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Computer Systems Science & Engineering 2021年第3期36卷 435-450页

作者： Adel Saad Assiri Management Information Systems Department College of BusinessKing Khalid UniversityAbhaSaudi Arabia

Artificial neural networks(ANNs)are one of the hottest topics in computer science and artificial intelligence due to their potential and advantages in analyzing real-world problems in various disciplines,including but not limited to physics,biology,chemistry,and ***,ANNs lack several key characteristics of biological neural networks,such as sparsity,scale-freeness,and *** concept of sparse and scale-free neural networks has been introduced to fill this *** sparsity is implemented by removing weak weights between neurons during the learning process and replacing them with random *** the network is initialized,the neural network is fully connected,which means the number of weights is four times the number of *** this study,considering that a biological neural network has some degree of initial sparsity,we design an ANN with a prescribed level of initial *** neural network is tested on handwritten digits,Arabic characters,CIFAR-10,and Reuters newswire *** show that it is possible to reduce the number of weights by up to 50%without losing prediction ***,in both cases,the testing time is dramatically reduced compared with fully connected ANNs.

关键词： Sparsity weak weights multi-layer neural network NN training with initial sparsity

Research on the process of fabricating a multi-layer metal micro-structure based on UV-LIGA overlay technology

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Nanotechnology and Precision Engineering 2019年第2期2卷 83-88页

作者： Yali Ma Wenkai Liu Chong Liu Department of Military Materials Distribution Army Military Transportation UniversityTianjin 300161China School of Mechanical Engineering Dalian University of TechnologyDalian 116023China

In this paper,we report the study of the process of fabricating a multi-layermetal micro-structure using UV-LIGA overlay technology,includingmask fabrication,substrate treatment,and UV-LIGA overlay *** solve the process problems in the masking procedure,the swelling problemof the first layer of SU-8 thick photoresist was studied *** 5μmline-width compensation and closed 20μmand 30μmisolation strips were designed and fabricated around the micro-structure *** pore problemin the Ni micro-electroforming layer was analyzed and the electroforming parameters were *** pH value of the electroforming solution should be controlled between 3.8 and 4.4 and the current density should be below 3 A/dm^*** solve the problems of high inner stress and incomplete development of the micro-cylinder hole array with a diameter of 30μm,the lithography process was *** pre-baking temperature was increased via gradient heating and rose every 5℃ from 65℃ to 85℃ and then remained at 85℃ for 50 min–1 *** addition,the full contact exposure was ***,a multi-layer metal micro-structure with high precision and good quality of microelectroforming layer was fabricated using UV-LIGA overlay technology.

关键词： UV-LIGA overlay technology SU-8 photoresist Micro-electroforming technology multi-layer metal micro-structure