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Effects of Ce concentrations on ignition temperature and surface tension of Mg-9wt.%Al alloy

China Foundry 2013年第2期10卷 108-111页

作者： Deng Zhenghua Li Huaji Zhao Wanjun Li Weibin School of Mechanical Engineering Chongqing Three Gorges University School of Material Science and Engineering Chongqing University Department of Mechanical Engineering Pusan National University

Magnesium alloys are well known for their excellent properties, but the potential issues with oxidation and burning during melting and casting largely limit its industrial applications. The addition of Ce in magnesium alloys can significantly raise ignition-proof performance and change the structure of the oxide film on the surface of the molten metal as well as the surface tension values. Surface tension is an important physical parameter of the metal melts, and it plays an important role in the formation of surface oxide film. In this present work, the ignition temperature and the surface tension of Mg-9wt.%AI alloy with different Ce concentrations were studied. Surface tensions was measured using the maximum bubble pressure method （MBPM）. Ignition temperature was measured using NiCr-NiSi type thermocouples and was monitored and recorded via a WXT-604 desk recording device. The results show that the ignition point of Mg-9wt.%AI alloy can be effectively elevated by adding Ce. The ignition temperature reaches its highest point of 720 ℃ when the addition of Ce is lwt.%. The surface tension of the molten Mg-9wt.%AI alloy decreases exponentially with the increase of Ce addition at the same temperature. Similarly, the experiment also shows that the surface tension of Mg-9wt.%AI alloy decreases exponentially with the increase of temperature.

关键词： magnesium alloy Ce surface tension ignition temperature

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Hydrodynamic interaction between overlapping domains during recurrence of registration within planar lipid bilayer membranes

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Physical Review E 2014年第3期89卷 032717-032717页

作者： Tao Han Trevor P. Bailey Mikko Haataja Department of Mechanical and Aerospace Engineering Princeton Institute for the Science and Technology of Materials (PRISM) and Program in Applied and Computational Mathematics (PACM) Princeton University Princeton New Jersey 08544 USA

Due to a thermodynamic coupling between the two leaflets comprising a lipid bilayer, compositional lipid domains residing within opposing leaflets are often found in registry. If the system is perturbed by displacing one domain relative to the other, diffusive and advective lipid fluxes are established to restore equilibrium and reestablish domain overlap. In this work, we focus on the advective part of the process, and first derive an analytical expression for the hydrodynamic drag coefficient associated with the advective flow for the special case of perfect domain overlap. The resulting expression identifies parameter regions where sliding friction between the leaflets dominates over viscous dissipation within the leaflets or vice versa. It is shown that in all practically relevant cases, sliding friction between the leaflets is the dominant factor. Finally, we investigate the domain separation dependence of the hydrodynamic drag coefficient via direct simulations of a continuum diffuse interface model, and provide useful empirical expressions for its behavior.

关键词： Drag coefficient

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A new method of digital manufacturing of orthoses

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Computer Modelling and New Technologies 2014年第3期18卷 271-275页

作者： Wei Ai, Yue He, Yan Wang J., Zhi Jian Wang, Yang State Key Laboratory of Mechanical Transmission Chongqing University Chongqing China Ningbo Institute of Material Technology and Engineering CAS Ningbo China Faculty of Science and Engineering University of Nottingham Ningbo China

The proportion of disabled people is rising and now represents 1 billion people-15% of the global population, which leads to increasingly demand for orthotic device. However, moulds for orthoses manufacturing through traditionally manual technique are often dedicated, and this causes problems such as long lead time, lack of flexibility, low-efficiency and material waste, further leading to serious financial burns and environmental pollution as well. In this paper, an innovative method is proposed to replace traditionally dedicated moulds with reconfigurable moulds utilizing screw-pins that are directly transferred to the vacuum forming of thermoplastic material at low cost for the fabrication of orthoses. In the developed system, the fast reconstruction of human body anatomy based on the 3D digital scanning, is introduced firstly, the reconfigurable mould utilizing screw-pins is then generated and machined based on the reconstructed human body anatomy. After this, vacuum forming is performed on the reconfigurable mould, which could be reused for different anatomical shape variations by adjusting screw-pins. Additionally, an intelligent database is developed and a lot of reconstructed anatomies, the best practices of experienced orthotists, optimal parameters for 3D digital scanning, reconfigurable mould generation and machining and vacuum forming are stored, which will allow rapid recall of the stored information to reduce too much man-machine interaction and expertise dramatically.

关键词： Molds

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Crystallographic Characterization of Cleavage Plane in Low-carbon Martensitic Steel

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materials Today: Proceedings 2015年 2卷 S655-S658页

作者： M. Tsuboi A. Shibata D. Terada N. Tsuji Department of Materials Science and Engineering Kyoto university Yoshida-honmachi Sakyo-ku Kyoto 606-8501 Japan Elements Strategy Initiative for Structual Material Kyoto university Yoshida-honmachi Sakyo-ku Kyoto 606-8501 Japan Department of Mechanical Science and Engineering Chiba Institute of Technology Tsudanuma Narashino 275-0016 Japan

The present study determined the crystallographic orientation of the cleavage plane in a low-carbon martensitic steel by two different methods using electron backscattering diffraction (EBSD) orientation analysis and three-dimensional imaging technique. One is the direct measurement of the cleavage plane by EBSD after tilting the specimen in SEM based on the line profiles of the 3D fracture surface image. The other is the trace analysis on EBSD orientation maps just beneath the fracture surface and the line profiles of the 3D fracture surface image. The both two methods demonstrated that cleavage fracture occurred on {001} planes in martensitic steel.

关键词： martensitic steel cleavage fracture EBSD crystallographic analysis three-dimensinal imaging technique

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Influence of Tempering on mechanical Properties of Ferrite and Martensite Dual Phase Steel

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materials Today: Proceedings 2015年 2卷 S667-S671页

作者： H. Li S. Gao Y. Tian D. Terada A. Shibata N. Tsuji Department of Materials Science and Engineering Kyoto University Yoshida honmachi Sakyo-ku Kyoto 606-8501 Japan Elements strategy Initiative for Structure Material Kyoto University Yoshida honmachi Sakyo-ku Kyoto 606-8501 Japan Department of Mechanical Science and Engineering Chiba Institute of Technology Tsudanuma Narashino 275-0016 Japan

This study investigated the change in microstructure and mechanical properties by tempering a low carbon dual phase steel composed of ferrite and martensite. The microstructure analysis revealed that tempering process resulted in the carbide precipitation and coarsening of martensite structures. The nanohardness of each phase (martensite and ferrite) decreased with increasing the tempering temperature. The ultimate tensile strength had a linear relationship with nanohardness ratio of martensite and ferrite. On the other hand, the uniform elongation firstly did not change by tempering at the temperature below 400 °C, but then decreased by tempering at the temperature above 400 °C with decreasing the nanohardness ratio. It was concluded that the nanohardness ratio can be a good parameter for controlling the mechanical properties of dual phase steels.

关键词： Dual phase steel martensite ferrite tensile strength elongation nanohardness nanoindentation nanohardness ratio tempering

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Processing and simulation of thin-walled shell with inner ribs formed by inner spinning technology

Processing and simulation of thin-walled shell with inner ri...

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2014 International Conference on Industrial,mechanical and Manufacturing science(ICIMMS 2014)

作者： Zhenjie Wang Baofeng Guo Shicheng Ma Education Ministry Key Laboratory of Advanced Forging and Stamping Science and Technology College of Mechanical EngineeringYanshan University Special Material and Technic Institution of Aerospace

The formation of a thin-walled shell structure with inner ribs by inner spinning technology was simulated using the finite element simulation software *** spinning force and deformation condition were calculated and analyzed in this *** indicate that a thin-walled cylindrical shell with uniform deformation can be obtained using the inner spinning process with good forming *** all the regions,the radial load was found to be greater than the axial load,with the radial load in the range of 0-270 *** skin and the back frame sections experience load peaks,which is in the expansion capacity of —200 mm for the skin *** peak load in the rear frame section is stable in a 15 mm stroke,which then gradually decreases to *** forming load in the front frame increases with the increase in the feed load of the spinning wheel,leading to the possibility of fracture in this *** axial spinning load is rather small in the range of 0-47 *** on the simulated values of these parameters,we demonstrated the formation of good quality2A12 aluminum alloy products using the inner spinning technology.

关键词： inner Spinning simulation thin-walled shell with inner ribs processing

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Correlation of multi-scale modeling and experimental results for the elastic modulus of trabecular bone

Correlation of multi-scale modeling and experimental results...

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2013 Annual Conference on Experimental and Applied Mechanics

作者： Hamed, Elham Novitskaya, Ekaterina Li, Jun Setters, Alexander Lee, Woowon McKittrick, Joanna Jasiuk, Iwona Civil and Environmental Engineering Department Technological Institute Northwestern University 2145 Sheridan Road Evanston IL 60208 United States Department of Mechanical and Aerospace Engineering University of California 9500 Gilman Dr. San Diego CA 92093 United States California Institute of Technology MC 301-46 1200 E California Blvd Pasadena CA 91125 United States Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign 1206 W. Green St. Urbana IL 61801 United States Materials Science and Engineering Program University of California 9500 Gilman Dr. San Diego CA 92093 United States

ISBN: (纸本)9783319007762

Trabecular bone is a porous nanocomposite material with a hierarchical structure. In this study, a multi-scale modeling approach, addressing scales spanning from the nanometer (collagen-mineral) to mesoscale (trabecular bone) levels, was developed to determine the elastic moduli of trabecular bone. Then, the predicted modeling results were compared with experimental data obtained by compression testing of bovine femur trabecular bone samples loaded in two different directions;parallel to the femur neck axis and perpendicular to that. Optical microscopy, scanning electron microscopy and micro-computed tomography techniques were employed to characterize the structure and composition of the samples at different length scales and provide the inputs needed for the modeling. To obtain more insights on the structure of bone, especially on the interaction of its main constituents (collagen and mineral phases), trabecular bone samples were deproteinized or demineralized and, afterwards, tested mechanically in compression. The experimental observations were used, in turn, to fine-tune the multi-scale model of bone as an interpenetrating composite material. Good agreement was found between the theoretical and experimental results for elastic moduli of untreated, deproteinized, and demineralized trabecular bones. © The Society for Experimental Mechanics, Inc. 2014.

关键词： Elastic moduli

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Metabolic Rate Monitoring and Weight Reduction/Management

Metabolic Rate Monitoring and Weight Reduction/Management

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Annual International Conference of the IEEE engineering in Medicine and Biology Society

作者： Pelagia-Irene Gouma Maen Alkhader Milutin Stanacevic Department of Material Science and Engineering Stony Brook University Stony Brook NY Department of Mechanical Engineering Stony Brook University Stony Brook NY Department of Electrical and Computer Engineering Stony Brook University Stony Brook NY

engineering research may provide tools to the individual as well as to the public in general, to effectively monitor welness and health patterns, such as metabolic rate and weight control. Ketone bodies and acetone gas emissions in exhaled breath and skin, in particular, may be used as biomarkers of fatty acid metabolism and may be used in diet control. Two types of technologies, resistive chemosensors and chemomechanical actuators are outlined here as examples of such tools currently under development and of great promise.

关键词： Monitoring Actuators Polymers Obesity Skin Biochemistry Blood

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The effect of Forming Speed on the Formability of a Zr-based Bulk Metallic Glass

The effect of Forming Speed on the Formability of a Zr-based...

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2014 International Conference on Advances in materials (ICAM 2014)

作者： Xiao WU Jianjun LI Zhizhen ZHENG Jinyang LI State Key Laboratory of Material Processing and Die and Mould Technology of Huazhong University of Science and Technology Department of Mechanical and Electronic Engineering Wuhan Textile University

Taking cup-shaped part(outer diameter D and wall thickness are chosen as 2.2 mm and 0.05 mm,respectively) as an example,the micro-back-extrusion forming process of a Zr55Cu30 Al10Ni5 bulk metallic glass(BMG) in its supercooled liquid region was studied by using finite-element analysis(FEM) and *** effect of forming speed on the formability was analyzed based on the extrusion load,the rheological behavior of the material and the microstructure of the formed *** was found that while the forming speed is below than 4 μm/s,the extrusion load increases obviously with the increasing in forming speed,otherwise,the BMG will follow non-newtonian flow and the forming load is insensitive to the forming *** parts fabricated at 2 μm/s are obviously crystallized due to the long retention time of metallic glasses at high temperature,a higher forming speed is benefit to enhancing the formability if the *** this basis,micro cup-shaped parts with only 0.05 mm in wall thickness are successfully extruded.

关键词： bulk metallic glass super-plasticity micro backward-extrusion forming speed

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Influence of welding condition on joint strength of friction stir lap welded dissimilar AA2024-AA7075 aluminum alloy sheets

Influence of welding condition on joint strength of friction...

引用

2014 International Conference on Brazing,Soldering and Special Joining Technologies

作者： Youbao Song Weimin Long Xinqi Yang Zhengzhou Research Institute of Mechanical Engineering State Key Laboratory of Advanced Brazing Filler Metals and Technology Tianjin Key Laboratory of Advanced Joining Technology School of Material Science and Engineering Tianjin University

In this paper, AA2024-T3 and AA7075-T6 aluminum alloy sheets were friction stir lap welded successfully. The influences of welding conditions including traveling speed, rotational speed, weld pitch(the ratio of traveling speed to rotational speed) and lapping sequence(either alloy is located as the upper sheet) on lap joint strength were investigated. It was found that the joint strength increases with the increase of traveling speed and weld pitch, decreases with the increase of rotational speed. The highest joint strength is obtained at the weld pitch of 0.20. 7075/2024 joints(7075 acts as the upper sheet) show higher failure load than 2024/7075 joints(2024 acts as the upper sheet) at lower traveling speeds while the opposite result appears at higher traveling speeds. The lap joints fracture in three modes: tensile mode of fracturing at the upper sheet on advancing side, shear mode of fracturing from lap interfaces of both sheets and the mix mode of the above. With the increase of traveling speed, the joints fracture in tensile mode, mix mode and shear mode in sequence.

关键词： Friction stir lap welding,Dissimilar aluminum alloys,Joint strength,Fracture mode

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