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EXPERIMENt AND SIMULAtION FOR tHICK-PLAtE BENDINGBy HIGH FREQUENCy INDUCtOR

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Acta Metallurgica Sinica(English Letters) 1998年第6期11卷 449-455页

作者： S.Imatani y.Okuno t.Inoue Kyoto Univ Kyoto Japan

In order to produce thick plates with complicated curved surface, a prototype bending machine by the use of high frequency inductor was developed. the bending mechanism is based on the localized stresses which are induced from the difference of temperature in thickness by the high frequency inductor. the operating speed and the thickness of plate were examined from the experiment, and the variation of the temperature was measured. Finite element analysis was carried out in the second part based on the experimentally obtained temperature distribution. the so-called Mindlin plate element was used in order to perform the simulation efficiently. the strategy to produce such curved surface in the practical process was discussed and further perspective of the production system was described. (Edited author abstract) 6 Refs.

关键词： plate bending high frequency inductor die-less forming thermoelasto-plastic deformation finite element method

A correlation between pulse diagnosis of human body and health monitoring of structures

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Earthquake Engineering and Engineering Vibration 2004年第1期3卷 117-125页

作者： C.C.Chang Henry t.y.yang Department of Civil Engineering Hong Kong University of Science and TechnologyHong Kong Department of Mechanical and Environmental EngineeringUniversity of California Department of Mechanical and Environmental Engineering University of California

the concept of health monitoring is a key aspect of the field of medicine that has been practiced for a long time. A commonly used diagnostic and health monitoring practice is pulse diagnosis, which can be traced back approximately five thousand years in the recorded history of China. With advances in the development of modern technology, the concept of health monitoring of a variety of engineering structures in several applications has begun to attract widespread attention. Of particular interest in this study is the health monitoring of civil structures. It seem natural, and even beneficial, that these two health-monitoring methods, one as applies to the human body and the other to civil structures, should be analyzed and compared. In this paper, the basic concepts and theories of the two monitoring methods are first discussed. Similarities are then summarized and commented upon. It is hoped that this correlation analysis may help provide structural engineers with some insights into the intrinsic concept of using pulse diagnosis in human health monitoring, which may of be some benefit in the development of modern structural health monitoring methods.

关键词： human health monitoring pulse diagnosis structural health monitoring vibration-based techniques local detection techniques

Microstructure and Mechanical Property of Ni Metal treated by Surface Mechanical Attrition

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材料热处理学报 2004年第5期25卷 161-164页

作者： t.y. Hsu School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200030China

A nanostructured surface layer can be formed in Ni metal treated by surface mechanical attrition (SMA). the microstructure was investigated by using optical microscope, X-ray diffractometer and transmission electron microscope, respectively. Mechanical property measurements indicate that the yield strength of the surface layer raises significantly while the tensile strength somewhat changes and the elongation percentage reduces severely compared with that of the inside layer. Meanwhile, yield-drop-like phenomenon occurs in the surface layer after SMA treatment. In order to compare the mechanical behavior of nanostructured materials with two phases, Fe-30Ni nanostructured alloy was also investigated.

关键词：显微结构表面层机械性能表面损耗镍合金

Effect of ultrasonic stirring on temperature distribution and grain refinement in Al-1.65%Si alloy melt

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中国有色金属学会会刊：英文版 2007年第4期17卷 691-697页

作者：李军文 t. Momono 付莹贾征 y. tayu College of Material and Chemical Engineering Liaoning University of Technology Faculty of Materials Science and Engineering Muro ran Institute of Technology Faculty of Materials Science and Engineering Muroran Institute of Technology

A series of experiments were conducted for Al-1.65%Si (mass fraction) alloy melt to study the formation of grain refining structure with ultrasonic stirring. the cooling curves of ingots with ultrasonic were measured and compared with those without ultrasonic. At the same time, the effect of the time of ultrasonic stirring on solidification structure of ingots was investigated. the influence of ultrasonic on the grain-refining efficiency of ingots was analyzed. In order to well understand the melts behavior under ultrasonic, by using ammonium chloride solution, the simulation experiment was carried out and the temperature distribution in ingot with or without ultrasonic was compared. the results indicate that the ultrasonic reduces the temperature inhomogeneity of melt, i.e. the ultrasonic helps to homogenize the melt temperature. the effect of stirring and heat generation in ingot start to occur with increasing the time of ultrasonic stirring.

关键词：合金熔化铝硅合金温度分布铸块晶粒细化

A high-fidelity design methodology using LES-based simulation and POD-based emulation:A case study of swirl injectors

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Chinese Journal of Aeronautics 2018年第9期31卷 1855-1869页

作者： Xingjian WANG Shiang-ting yeh yu-Hung CHANG Vigor yANG School of Aerospace Engineering Georgia Institute of Technology

Engineering design is undergoing a paradigm shift from design for performance to design for affordability, operability, and durability, seeking multi-objective optimization. to facilitate this transformation, significantly extended design freedom and knowledge must be available in the early design stages. this paper presents a high-fidelity framework for design and optimization of the liquid swirl injectors that are widely used in aerospace propulsion and power-generation systems. the framework assembles a set of techniques, including Design Of Experiment(DOE), high-fidelity Large Eddy Simulations(LES), machine learning, Proper Orthogonal Decomposition(POD)-based Kriging surrogate modeling(emulation), inverse problem optimization, and uncertainty quantification. LES-based simulations can reveal detailed spatiotemporal evolution of flow structures and flame dynamics in a high-fidelity manner, and identify important injector design parameters according to their effects on propellant mixing, flame stabilization, and thermal *** a given a space of design parameters, DOE determines the number of design points to perform LES-based simulations. POD-based emulations, trained by the LES database, can effectively explore the design space and deduce an optimal group of design parameters in a turn-around time that is reduced by three orders of magnitude. the accuracy of the emulated results is validated, and the uncertainty of prediction is quantified. the proposed design methodology is expected to profoundly extend the knowledge base and reduce the cost for initial design stages.

关键词： Emulation High-fidelity design Kriging Large Eddy Simulation(LES) Proper Orthogonal Decomposition(POD) Swirl injector

Frequency equations of nonlocal elastic micro/nanobeams with the consideration of the surface effects

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Applied Mathematics and Mechanics(English Edition) 2018年第8期39卷 1089-1102页

作者： H.S.ZHAO y.ZHANG S.t.LIE School of Civil and Environmental Engineering Nanyang Technological University

A nonlocal elastic micro/nanobeam is theoretically modeled with the consideration of the surface elasticity, the residual surface stress, and the rotatory inertia,in which the nonlocal and surface effects are considered. three types of boundary conditions, i.e., hinged-hinged, clamped-clamped, and clamped-hinged ends, are examined. For a hinged-hinged beam, an exact and explicit natural frequency equation is derived based on the established mathematical model. the Fredholm integral equation is adopted to deduce the approximate fundamental frequency equations for the clamped-clamped and clamped-hinged beams. In sum, the explicit frequency equations for the micro/nanobeam under three types of boundary conditions are proposed to reveal the dependence of the natural frequency on the effects of the nonlocal elasticity, the surface elasticity, the residual surface stress, and the rotatory inertia, providing a more convenient means in comparison with numerical computations.

关键词： Fredholm integral equation micro/nanobeam natural frequency nonlocal elasticity surface effect

Pressure and Discharge-Voltage Dependence of Self-Sustaining Pulses in Air-Glow Discharge

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Chinese Physics Letters 2012年第5期29卷 181-184页

作者： A.A.Azooz y.A.Al-Jawaady Z.t.Ali Department of Physics College of ScienceMosul UniversityMosulIraq

the details of formation of micro discharges in air-glow discharge plasma are experimentally *** number of micro discharges formed per second is strongly related to both pressure and discharge *** number tends to show reflections of the Patchen curve as far as its pressure dependence is *** dischargevoltage dependence indicates that the transition from normal to abnormal glow discharge is not a sudden one,but has its roots during the normal glow stage and is initiated by the micro discharges which can be regarded as the early stage of abnormal glow.

关键词： details initiated roots

Phytotoxicity of cadmium on protein, proline and antioxidant enzyme activities in growing Arachis hypogaea L. seedlings

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Journal of Environmental Sciences 2008年第2期20卷 199-206页

作者： N Dinakar P C Nagajyothi S Suresh y Udaykiran t Damodharam Department of Environmental Sciences Sri Venkateswara UniversityTirupatiAndhra Pradesh-517 502India.

Phytotoxicity of cadmium on growing Arachis hypogaea L. seedlings was studied. Seeds were exposed to 25, 50, and 100 μmol/L CdCl2 concentrations, for a period of 10, 15, 20 and 25 d. the extent of damage to chlorophyll, protein, proline, nitrate and nitrite reductase, antioxidant enzyme activity in leaves and roots were evaluated after 10 d of cadmium stress. the higher concentration of cadmium （100 μmol/L） resulted （leaves and roots） total chlorophyll 91.01%, protein 79.51%, 83.61%, nitrate reductase 79.39%, 80.72% and nitrite reductase 77.07%, 75.88% activity decreased with increase in cadmium concentrations and exposure periods. Cadmium caused significant changes in the activity of antioxidative enzymes. Contrastingly Cd treated plant tissues showed an increase in proline 159.87%, 239.6%, gluthion reductase （GR） 337.72%, 306.14%, superoxide disumutase （SOD） 688.56%, 381.72%, ascorbate peroxidase （APX） 226.47%, 252.14%, peroxidase （POD） 72.19%, 60.29% and catalase （CAt） 228.96%, 214.74% as compared to control. Cadmium stress caused a significant increase in the rate of SOD activity in leaves and roots of plant species. Results show the crop A. hypogaea is highly sensitive even at very low cadmium concentrations.

关键词： toxicological effects cadmium protein proline antioxidant enzymes

Microstructure and brazing mechanism of porous Si_3N_4/Invar joint brazed with Ag-Cu-ti/Cu/Ag-Cu multi-layered filler

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Journal of Materials Science & technology 2018年第4期34卷 713-719页

作者： J.Zhang J.y.Liu t.P.Wang School of Materials Science and Engineering Harbin Institute of Technology

Porous Si3N4 was brazed to Invar alloy in this study, and Ag-Cu-ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe2ti and Ni3ti intermetallic compounds. the effects of the brazing temperature and the thickness of Cu interlayer on the microstructure and mechanical properties of brazed joints were investigated. the typical microstructure of the joint brazed with multi-layered filler was porous Si3N4/tiN ＋ ti5Si3/Ag-Cu eutectic[Cu[Ag-Cu eutectic/Cu-rich layer ＋ diffusion layer/Invar. When the brazing temperature increased, the reaction layer at the ceramic/filler interface grew thicker and the Cu interlayer turned thinner. As the thickness of Cu interlayer increased from 50 to 150 μm, the joint strength first increased and then decreased. In this research, the maximum shear strength （73 MPa） was obtained when being brazed at 1173 K with a 100 μm Cu interlayer applied in the filler, which was 55% higher than that brazed with single Ag-Cu-ti brazing alloy and had reached 86% of the ceramic. the release of residual stress and the barrier effect of Cu interlayer to inhibit the formation of Fe2ti and Ni3ti intermetallics played the major role in the improvement of joint strength.

关键词： Porous Si3N4 Invar alloy Brazing Microstructure Mechanical properties