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Study on Theory and Application of the Energy Method used for Analyzing Compressive Instability in Sheet Forming

厦门大学学报（自然科学版） 2002年第S1期41卷 126-127页

作者： XIONG Zhi-qing 1, XIE Lan-sheng 2.(1. Department of mechanical engineering, Nanjing Institute of Techno logy, Nanjing 2.0013, China 2. {2. of mechanical and electrical engineering, Nanjing University of Aer onautics and Astronautics, Nanjing 2.0016, China)

It is pointed out that there was serious weakness w he n using the energy method for studying compressive plastic instability in sheet forming in the past. Where applying the deduced instability strengths to relativ e engineering analysis, theoretical solutions were away from practices. Its basi c reason is that simplified process in mathematical analysis of elastic bending energy was completely applied to that of plastic bending energy. Where the cambe r expressed by function of displacement normal to a plate was approximated to re alistic deflective camber, the displacement of deflected plate to compressed dir ection was neglected. With the aid of the improved instability strengths, the pr edictions on both critical buckling dimension of blank in cup deep-drawing with out blankholder through cylindrical die or conical die and the minimum blankhold er pressure to prevent buckling under constant load are universally in agreement with both experimental results and experiential data. On the bases of above-mentioned improvement, the approximate expressions for bo th the curvature and the twist used in equation of the energy of elastic bending are also ameliorated. Thus the obtained general equations for both the energy a nd the work done by internal force in plastic bending of a plate are more precis e than before. In the analyses of plastic buckling of shell with bending moment, the effect of bending moment is considered through the work done by simulative bending for ce. The method proposed in this paper can not only simplify analyses but also ge t practical result.

关键词： sheet forming deep-drawing buckling energy me thod

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Kinetics analysis of volume phase transition of intelligent neutral thermo-sensitive hydrogels

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Science China(Physics,Mechanics & Astronomy) 2008年第5期51卷 532-540页

作者： WANG XiaoGui1 & LI YiQuan2.1.college of mechanical {2.,Zhejiang University of Technology,Hangzhou 310032.China 2.School of mechanical & Electronic {2.,Changchun University of Science and Technology,Changchun 13002.,China 1. college of mechanical {2. Zhejiang University of Technology Hangzhou 310032 China 2. School of mechanical & Electronic engineering Changchun University of Science and Technology Changchun 130022 China

In this work,utilizing the first law of thermodynamics and the Flory mean-field theory,the kinetic deformation studies concerning the volume phase transition of the neutral thermo-sensitive hydrogels were performed *** hydrogel was assumed as a biphasic mixture medium in the framework of the continuum mixture *** the energy conservation of the thermodynamics system of the hydrogel,the governing equations for the kinetics of the nonlinear large deforma-tion were *** explicit analytical expressions of the effective stress tensor and the chemical potential of the fluid of the thermo-sensitive hydrogel PNIPA were also obtained from the Helmholtz free energy,which can model the steady-static volume phase transition quantitatively.

关键词： thermo-sensitive hydrogel volume phase transition effective stress energy conservation

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Plasma Spray Forming

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厦门大学学报（自然科学版） 2002年第S1期41卷 33-34页

作者： FANG Jian-cheng 1, XU Wen-ji 2. SHI Yu-ying 1 (1.college of mechanical {2. and Automation, HQU, Quanzhou 362.11, China 2.School of mechanical {2., DUT, Dalian 11602., China)

In the course of plasma spray, the plasma jet is comprehensively functioned by such effects as thermal pinch, magnetic pinch and mechanical compression and the flow is jetting at a high speed, the energy is concentrated and its center temperature is so high as to reach upwards of 15 000 ℃ which is capable of melting various kinds of materials inclusive of ceramic, it has a broad applied prospects in the fields of automobile, electronics, telecommunications, medical treatment, air navigation & space navigation and light industries etc because of being able to rapid fabricate thin-walled metals, ceramics and alloy parts thereof, metal moulds, functionally gradient material moulds and so on, and it has become a research spotlight for the scholars. The technology of plasma spray forming (PSF) is introduced, and the two different kinds of technique presented in this paper are studied. Some typical links in the course of technical process is also analyzed, including original prototype fabrication and surface treatment, post-treatment of formed workpiece and demoulding methods. When spraying, it should select the appropriate making methods of prototype according to the dimensions, shapes and forming accuracy as required by the formed parts. At the same time, it should be paid to the characteristic of the material for the prototype. The main purpose of surface treatment of the prototype is to raise the quality of formed parts and ensure the integrity demoulding of the coating. The method of the prototype’s surface treatment is closely related to the demoulding method, which is mainly comprised of destructive demoulding, non-destructive demoulding and composite demoulding, and is key technology in PSF. In order to eliminate these intrinsic defects and improve its performance, the fabricated parts can be given the necessary post-treatment so as to further raise the mechanical strength and surface quality. There are many methods for the post-treatment such as chemical reinforc

关键词： plasma spray forming forming technique

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Tribological Properties of PVA-H Composites Reinforced by Nano-HA Particles

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Journal of Wuhan University of Technology(Materials Science) 2007年第3期22卷 490-493页

作者：吴刚 School of mechanical engineering Shanghai Jiaotong University

The friction and wear behaviors of tribological mechanical components were studied on a four-ball tester under dry conditions, and the wear mechanism was analyzed by observed worn surface using a scanning electron microscope （SEM）. It was found that the friction and wear properties were improved by the addition ofnano HA particles. The composite containing 1 wt% nano HA had the optimum friction coefficient. It is also found that the addition of nano HA increases the wear resistance of oure PVA-H and PVA-H composites.

关键词： articular cartilage composites wear friction coefficient corrosion-abrasion

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Effect of Preparation Methods on mechanical Properties of PVA/HA Composite Hydrogel

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Journal of Bionic engineering 2010年第3期7卷 235-243页

作者： Dekun Zhang~1, Junjie Duan~1, Dagang Wang~2. Shirong Ge~2.1. School of Materials Science and engineering, China University of Mining and Technology Xuzhou 2.1116, P. R. China 2. School of mechanical and {2. engineering, China University of Mining and Technology, Xuzhou 2.1116, P. R. China [a] School of Materials Science engineering China University of Mining Technology Xuzhou 221116 P. R. China [b] School of Mechanical electrical engineering China University of Mining Technology Xuzhou 221116 P. R. China

Poly(vinyl alcohol) (PVA)/hydroxyapatite (HA) composite hydrogel specimens were prepared with 15% PVA and 1%,2., 3%, 4% and 5% HA by repeated freezing-thawing. The tests of static and dynamic mechanical properties were carried out todiscuss the influence of different contents of HA and freezing-thawing cycles on the mechanical properties of PVA/HA compositehydrogel. The results of static mechanical tests showed that the PVA/HA composite hydrogel with 3% HA and ninefreezing-thawing cycles had excellent stress relaxation properties, higher relaxation ratio, lower stress equilibrium value andpresented better properties of creep and recovery. The results of dynamic mechanical test showed that the PVA/HA compositehydrogel with nine freezing-thawing cycles had higher storage modulus and loss modulus, so was the PVA/HA compositehydrogel with 3% HA.

关键词： composite hydrogel HA contents freezing-thawing cycles static properties dynamic properties

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Fractal Characteristic of Pits Distribution on 304 Stainless Steel Corroded Surface and Its Application in Corrosion Diagnosis

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Journal of Wuhan University of Technology(Materials Science) 2007年第3期22卷 389-393页

作者：梁成浩 Electromechanics & Materials engineering college Dalian Maritime University

Electrochemical techniques and fractal theory were employed to study the corrosion behaviors and pits distribution characteristics on the corroded surfaces of 304 stainless steel exposed in FeCl3 solution. Fractal features of pits distribution over the corroded surfaces were observed and described by the fractal dimension. A 5-8-2.back-propagation （BP） artificial neural network model for the diagnoses of the pitting corrosion rate and pits deepness of 304 stainless steel under various conditions was developed by considering the fractal dimension as a key parameter for describing the pitting corrosion characteristics. The predicted results are well in agreement with the experimental data of pitting corrosion rate and pit deepness. The max relative errors between their experimental and simulation data are 6.69% and 4.62., respectively.

关键词： 304 stainless steel pits distribution fractal neural network diagnosis

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Description to wear debris boundaries by radar graph fractal method

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Chinese Science Bulletin 2007年第16期52卷 2285-2290页

作者： LIU HongTao1,2.& GE ShiRong1 1 Institute of Tribology and Reliability engineering,China University of Mining & Technology,Xuzhou 2.1008,China 2.college of {2. and electrical engineering,China University of Mining & Technology,Xuzhou 2.1116,China Institute of Tribology and Reliability engineering China University of Mining and Technology Xuzhou 221008 China

In this paper,radar graph fractal method is introduced to describe wear debris boundaries. Research results show that it is a nice way to describe wear debris boundaries. Since the longest axis is selected as the first coordinate axis,its center point selected as the center point of the radar graph,and the co-ordinate value of wear debris boundary selected as the measure parameter,the limitations existing in Yard fractal measure method can be avoided. For any wear debris,its radar graph fractal dimension value is one and only,and as the wear debris shape changes from round to strip,the radar graph fractal dimension value also changes from low to high,showing strong uniqueness and independence. Due to the fact that the researched wear debris is gotten in different wear states,the results also prove that radar graph fractal dimension value is correlated with frictional pairs work condition and wear state. Radar graph fractal method is compared with Yard fractal measure methods,and results show that ra-dar graph fractal dimension values gotten from different wear debris have enough value grads to avoid effect of errors,and provide higher sensitivity for wear debris shape. This paper also discusses the influencing factors for radar graph fractal method. With the increase of the decomposing degree value,the radar graph fractal dimension tends to keep stable at one certain value,showing the typical characteristic of the fractal theory. All this proves that radar graph fractal method is an effective description method for wear debris boundaries.

关键词：磨粒边界雷达图表分形法

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Nanostructured Sulfide Composite Coating Prepared by Atmospheric Plasma Spraying

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材料工程 2006年第Z1期34卷 281-284页

作者： GUAN Yao-hui~1,XU Yang~1,ZHENG Zhong-yu~2.TONG Xiao-hui~2.1 engineering college of China Agricultural University,Beijing 100083,China 2.Beijing Research Institute of {2. & electrical Technology,Beijing 100083,China) engineering college China Agricultural University Beijing 100083 China Beijing Research Institute of mechanical and electrical Technology Beijing 100083 China

Nanostructured FeS-SiC coating was deposited by atmospheric plasma spraying（APS）.The microstructure and phase composition of the coating were characterized with SEM and XRD,*** addition,the size distribution of the reconstituted powders and the porosity of the coating have been *** was found that the reconstitiuted powers with sizes in the range of 2. to 80 μm had excellent flowability and were suitable for plasma spraying *** as-sprayed FeS-SiC composite coating exhibited a bimodal distribution with small grains（30～80nm） and large grains（100～2.0nm）.The coating was mainly composed of FeS and SiC,a small quantity of Fe1-xS and oxide were also *** porosity of the coating was approximately 19%.

关键词： plasma spraying nanostructured FeS-SiC composite coating

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Ceramics Grinding Under the Condition of Constant Pressure

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厦门大学学报（自然科学版） 2002年第S1期41卷 124-125页

作者： SHEN Jian-yun 1,2. LUO Can-bin 1, XU Xi-peng 1, XU Yan-sheng 2.(1. college of mechanical {2. and Automation, Huaqiao Univers ity, Quanzhou 362.11, China 2. college of mechanical {2., Tianjin University, Tianjin 300072. China )

To meet the increasing demand on the quality and co st of precision components for the semiconductor industries, extensive studies on high efficiency and precision machining of ceramic materials have been conducted over the past several years. It is found that the effects of grinding pressure and rotational speed of spindle in the machining for the ceramic materials are v ery significant on the quality of the grinding process. In order to achieve stab le grinding conditions for improved performance, a new grinding control scheme i n which the grinding pressure is maintained constant throughout the grinding pro cess was carried out in the present study. The surface quality of ground ceramics depends on the mechanism of material remo val in the vertical grinding process. For grinding of Si 3N 4 and glass under the condition of constant pressure, increasing pressure enhances material remova l rate, and at the same time causes more machining-induced microcracks on the g round surfaces. Along with the analysis of tangential forces, specific grinding energy, and the micro observations on ground surfaces, it can be found that low pressure and high wheel speed should be selected to high efficiently remove cera mics in ductile mode in the vertical grinding. From the theoretically analytical and measured grinding temperatures in the vert ical grinding of ceramics, it is found that the analytical temperature profile w ithε= 55% has the same trend with the measured one. The measured temperature is higher that the analytical one at the beginning stage of grinding process, whic h might be contributed to the unstable grinding condition of this stage. The gri nding temperatures in the vertical grinding of ceramics under a constant are not high enough for glassy phase formation, and may not reduce surface fracture as expected. However, the temperature in dry grinding may cause thermal damage to t he resin bond diamond wheel, thereby resulting in low quality workpiece surface.

关键词： ceramic vertical grinding grinding force gr inding energy grinding temperature

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Morphology and reaction force of toes of geckos freely moving on ceilings and walls

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Science China(Technological Sciences) 2010年第6期53卷 1688-1693页

作者： WANG ZhouYi1,2.GU WenHua1,2.WU Qiang1,2.JI AiHong1 & DAI ZhenDong1 1 Institute of Bio-inspired Structure and Surface engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 2.0016,China 2.college of {2. and electrical engineering,Nanjing University of Aeronautics and Astronautics,Nanjing 2.0016,China 1. Institute of Bio-inspired Structure and Surface engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China2. College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

The 3-dimensional interactions between toes of a gecko and substrates (ceilings or walls) were measured when it moves on ceilings or walls by using a 3-dimensional force measuring array,and the correspondent morphology of the gecko toes was recorded by a high speed *** study aims to understand the relationship between adhesive and shear forces generated by the toes of the gecko and the locomotion behavior when it walks on walls and *** showed that shear force is along the toe-only 12.6° and 3.1° away from the toe for wall-climbing and ceiling-crawling,respectively while the adhesion is big enough to balance the body weight and *** shear forces generated by the first and the fifth toes are in opposite directions;this redundant force increases the reliability of adhesion and stability of *** support angles of toes are equal approximately for ceiling-crawling and *** study greatly inspires the design of a gecko-like robot.

关键词： reaction force of toe morphometrics ceiling redundant force gecko-like robot

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