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LEVEL SET METHOD FOR TOPOLOGICAL OPTIMIZATION APPLYING TO STRUCTURE, MECHANISM AND MATERIAL DESIGNS

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Chinese Journal of mechanical engineering 2004年第2期17卷 200-209页

作者： Mei Yulin Wang Xiaoming department of mechanical engineering,Dalian University of Technology,Dalian 116024,china department of mechanical engineering Dalian University of Technology Dalian 116024 China

Based on a level set model, a topology optimization method has been suggestedrecently. It uses a level set to express the moving structural boundary, which can flexibly handlecomplex topological changes. By combining vector level set models with gradient projectiontechnology, the level set method for topological optimization is extended to a topologicaloptimization problem with multi-constraints, multi-materials and multi-load cases. Meanwhile, anappropriate nonlinear speed, mapping is established in the tangential space of the activeconstraints for a fast convergence. Then the method is applied to structure designs, mechanism andmaterial designs by a number of benchmark examples. Finally, in order to further improvecomputational efficiency and overcome the difficulty that the level set method cannot generate newmaterial interfaces during the optimization process, the topological derivative analysis isincorporated into the level set method for topological optimization, and a topological derivativeand level set algorithm for topological optimization is proposed.

关键词： Level set method Topology optimization Mean curvature flow Materialdesign Mechanism design Topological derivative

SEMI-DEFINITE RELAXATION ALGORITHM FOR SINGLE MACHINE SCHEDULING WITH CONTROLLABLE PROCESSING TIMES

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Chinese Annals of Mathematics,Series B 2005年第1期26卷 153-158页

作者： CHENFENG ZHANGLIANSHENG departmentofMathematics ShanghaiUniversityShanghai200436China／／DepartmentofIndustrialEngineeringandManagementShanghaiJiaotongUniversityShanghai200030China. departmentofMathematics ShanghaiUniversityShanghai200436China

The authors present a semi-definite relaxation algorithm for the scheduling problem with controllable times on a single machine. Their approach shows how to relate this problem with the maximum vertex-cover problem with kernel constraints (MKVC).The established relationship enables to transfer the approximate solutions of MKVCinto the approximate solutions for the scheduling problem. Then, they show how to obtain an integer approximate solution for MKVC based on the semi-definite relaxation and randomized rounding technique.

关键词： Scheduling with controllable times Semi-definite programming Approximation algorithm

Semi-solid Processing of Al-7Graghite Composite

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Journal of University of Science and Technology Beijing 2001年第3期8卷 203-206页

作者： Peng Zhang, Yunhui Du, Daben Zeng department of mechanical engineering, Tsinghua University, Beijing 100084, china department of mechanical engineering Tsinghua University Beijing 100084 China

Al-7graphite composite was processed using Al-7graphite mushy prepared by electromagnetic-mechanical stirring method, and the influence of solid fraction on the distributing of graphite particles in ingot was studied. The results shows that the relationship between solid fraction and stirring temperature of mushy is: f(s) = 591.5-0.897 t (where f(s) is the solid fraction, t is the stirring temperature). For Al-7graphite composite, with the increasing of solid fraction, the aggregation extent of graphite particles reduced gradually, and when solid fraction was larger than 30%, graphite particles could distribute evenly in ingot.

关键词： Al-7graphite composite electromagnetic-mechanical stirring method distributing of graphite particles solid fraction stirring temperature

To enhance the reproduction of Phanerochaete chrysosporium by adding natural lixiviums in liquid medium

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Journal of Environmental Sciences 2003年第6期15卷 808-814页

作者： LIN Gang, WEN Xiang-hua, QIAN Yi (department of Environmental Science and engineering, Tsinghua University, Beijing 100084, china. department of Environmental Science and engineering Tsinghua University Beijing 100084 Chin

Great promotion to the reproduction of white rot fungus Phanerochaete chrysosporium by adding natural lixiviums such as from wood, maize core and potato in liquid medium was found in this research. Incubated in the liquid medium contained 10 mg/L glucose as carbon source with natural lixiviums for three days, the production of mycelium pellet reaches more than 80 g/L, which is 5 times more than that of without natural lixiviums. Incubated in the liquid medium contained 5 mg/L glucose as carbon source with natural lixiviums for three days, the production of mycelium pellet can reach 69.5 g/L, while the production in the medium without natural lixiviums is very low. When the liquid medium contained 1—20 g/L glucose as carbon source, the production of mycelium pellet in 3 d can only reach 12.5 g/L to 14.5 g/L. The fungus in the medium with potato lixiviums are easily contaminated by other microorganisms and in the medium with maize core lixiviums are easily bulking, while in the medium with wood lixiviums are neither easily contaminated nor bulking. Medium with wood lixiviums can produce more pellet than other medium, endure contamination and keep better sedimentation capacity. So that, wood lixivium is better additive to the culture of white rot fungi in liquid medium. Addition of the mixture of wood, maize core and potato lixiviums is of advantage to the production of mycelium pellet. The difference of the production in the medium with different amount of wood lixiviums showed little in the first 3 d, while it expanded after 3 d. Wood lixiviums stimulate the growth of P. chrysosporium instead of supply organics which fungi need.

关键词： white rot fungi medium additive

An Expert System in FRP Composite Material Design

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Journal of Materials Science & Technology 2001年第5期17卷 556-560页

作者： Qingfen LI, Zhaoxia CUI and Weimin WANG College of mechanical & Electrical engineering, Harbin engineering University, Harbin 150001, china.Jianhua GAO department of mechanical engineering, Shanghai Jiao Tong University, Shanghai 200030, china Coll. of Mech. and Electron. Eng. Harbin Eng. Univ. Harbin 150001 China

An expert system prototype for fibre-reinforced plastic matrix (FRP) composite material design, ESFRP, has been developed. The system consists of seven main functional parts: a general inference engine, a set of knowledge bases, a material properties algorithm base, an explanation engine, various data bases, several function models and the user interface. The ESFRP can simulate human experts to make design scheme for fibre-reinforced plastics design, FRP layered plates design and FRP typical engineering components design. It can also predict the material properties and make strength analysis according to the micro and macro mechanics of composite materials. A satisfied result can be gained through the reiterative design.

关键词： An Expert System in FRP Composite Material Design FRP

A mechanical MODEL FOR THE CHIP SIDE DEFORMATION IN ALUMINIUM ALLOY CUTTING

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中国有色金属学会会刊：英文版 1995年第4期5卷 168-172页

作者： Xia Wei Li Yuanyuan Zhou Zehua(department of mechanical engineering,South china.University of Technology,Guangzhou 510641) South china.Univ of Technology Guangzhou China

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关键词： metal cutting mechanical model cutting force chip side deformation

Nitriding of Hard Fe Electrodepositionand Its Effects on Wear Resistance

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Journal of Materials Science & Technology 2001年第2期17卷 271-274页

作者： Chenghui GAO, Dajian CHEN and Baiyang ZHOU department of mechanical engineering, Fuzhou University, Fujian, Fuzhou 350002, china Dept. of Mech. Eng. Fuzhou Univ. Fuzhou 350002 China

Nitriding is employed for the hard Fe electrodeposition to produce a hard-facing and antiwear coating. It only takes 1 h for the hard Fe coating, which is much shorter than nitriding the Fe and steel. The results showed that the nitriding can increase the microhardness, wear resistance of the coating, as well as the bonding strength of the coating with the substrate. Additionally it can eliminate the brittleness, turn the internal stress of the coating from tension to compression. The wear resistance of the nitrided Fe coating is 4.6 times as high as that of Cr coating. It is simple and economic to combine hard Fe electroplating and nitriding, which is a good technology of the tribological surface modification.

关键词： Fe Nitriding of Hard Fe Electrodepositionand Its Effects on Wear Resistance

MESHLESS METHOD FOR 2D MIXED-MODE CRACK PROPAGATION BASED ON VORONOI CELL

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Acta Mechanica Solida Sinica 2003年第3期16卷 231-239页

作者： Lou Luliang Zeng Pan (department of mechanical engineering,Tsinghua University,Beijing 100084,china. department of mechanical engineering Tsinghua University Beijing 100084 China

A meshless method integrated with linear elastic fracture mechanics(LEFM)is presented for 2D mixed-mode crack propagation *** domain is divided automatically into sub-domains based on Voronoi cells,which are used for quadrature for the potential energy. The continuous crack propagation is simulated with an incremental crack-extension method which assumes a piecewise linear discretization of the unknown crack *** each increment of the crack extension,the meshless method is applied to carry out a stress analysis of the cracked *** J-integral,which can be decomposed into mode Ⅰ and mode Ⅱ for mixed-mode crack,is used for the evaluation of the stress intensity factors(SIFs).The crack-propagation direction,predicted on an incremental basis, is computed by a criterion defined in terms of the SIFs. The flowchart of the proposed procedure is presented and two numerical problems are analyzed with this *** meshless results agree well with the experimental ones,which validates the accuracy and efficiency of the method.

关键词： meshless method crack propagation mixed-mode crack Voronoi cell

STRESS-STRAIN FINITE ELEMENT ANALYSIS AND FATIGUE LIFE PREDICTION FOR BOLTED CONNECTIONS

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Chinese Journal of mechanical engineering 2002年第1期15卷 75-78页

作者： Wang Ziqin Xie Qingsheng mechanical engineering department，Guizhou University of Technology，Guiyang 550003，china mechanical engineering department Guizhou University of Technology Guiyang 550003

A cyclic plasticity model is used into finite element (FE) method to obtainthe details of elastic-plastic stress-strain in the bolts under cyclic axial loading. Two criteriain multiaxial fatigue are employed to predict fatigue lives of bolts. The predicted fatigue livesare in favorable agreement with the experimental results for machined bolts.

关键词： Finite element Fatigue Bolted connection