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PARTICLE DISTRIBUTION IN CENTRIFUGAL ACCELERATING FIELDS

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Chinese Journal of Mechanical Engineering 2003年第3期16卷 329-333页

作者： Yu SirongZhang XinpingHe ZhenmingLiu YaohuiCollege of Materials Scienceand Engineering,jilin University,Changchun 130025, China College of Materials Science and Engineering Jilin University Changchun 130025

Based on continuum theory and moving law of particles, a model is presentedto obtain gradient distribution of particles in centrifugal accelerating field, by which theparticle distribution in gradient composite material can be predicted. The simulation shows withincreases in rotating time, four regions gradually appear from the internal periphery to theexternal one, they are free region, transition region, steady region and surface reinforced region,and the latest three regions are defined as a rich region. Finally, the steady region disappears,and the rich region only includes transition region and surface reinforced region. The influences ofcentrifugal acceleration coefficient G, primary volume fraction phi_0, pouring temperature theta_pand density difference between the particle and the metal matrix on particles gradient distributionare studied in detail. The results of the theoretical analysis agree with experiment ones. Both ofanalysis and experiment results indicate that with the increase in G and theta_p the particledistribution becomes more centralized and the consistence of particle in the surface peripherybecomes larger.

关键词： Centrifugal accelerating field Particles Numerical simulation Functionalgradient material

Efficient computation for dynamic responses of systems with time-varying characteristics

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Acta Mechanica Sinica 2009年第5期25卷 699-705页

作者： Liang Ma Yudong Chen Suhuan Chen Guangwei Meng Department of Mechanics, Nanling Campus,jilin University, 130025 Changchun, China Department of Mechanics Nanling Campus Jilin University Changchun China

Based on Neumman series and epsilon-algorithm, an efficient computation for dynamic responses of systems with arbitrary time-varying characteristics is investigated. Avoiding the calculation for the inverses of the equivalent stiffness matrices in each time step, the computation effort of the proposed method is reduced compared with the full analysis of Newmark method. The validity and applications of the proposed method are illustrated by a 4-DOF spring-mass system with periodical time-varying stiffness properties and a truss structure with arbitrary time-varying lumped mass. It shows that good approximate results can be obtained by the proposed method compared with the responses obtained by the full analysis of Newmark method.

关键词： Dynamic responses Efficient computation Epsilon-algorithm Time-varying characteristics

DYNAMIC OPTIMIZATION FOR UNCERTAIN STRUCTURES USING INTERVAL METHOD

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Acta Mechanica Solida Sinica 2003年第2期16卷 141-146页

作者： Chen Suhuan Wu Jie Liu Chun (Department of Mechanics,jilin University,Changchun 130025,China) Department of Mechanics Jilin University Changchun 130025 China

An interval optimization method for the dynamic response of structures with inter- val parameters is *** matrices of structures with interval parameters are ***- bining the interval extension with the perturbation,the method for interval dynamic response analysis is *** interval optimization problem is transformed into a corresponding de- terministic *** the mean values and the uncertainties of the interval parameters can be elected design variables,more information of the optimization results can be obtained by the present method than that obtained by the deterministic *** present method is implemented for a truss *** numerical results show that the method is effective.

关键词： interval optimization interval parameter structure interval extension of function dynamic interval response

NUMERICAL METHOD FOR PREDICTION OF NET-SHAPED BLANK IN MULTI-POINT FORMING OF SHEET METAL

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Chinese Journal of Mechanical Engineering 2002年第4期15卷 314-318页

作者： Cai Zhongyi Li Mingzhe Cui Xiangji Roll Forging Institute, jilin University, Changchun 130025, China Roll Forging Institute Jilin University Changchun 130025

A new numerical method to predict the initial blank geometry from the desiredobjective shape of parts is presented. Based on the conditions that the deformations in materialare most evenly distributed and that the volume remains constant, a positive definite functional forblank design is constructed. The functional is minimized by an iterative scheme of finite element,and then the optimal initial configuration is obtained. The method is easy and expedient to use. Theresults of numerical simulation of forming process and multi-point forming experiments for sheetmetal demonstrate that good precision is achieved by the proposed method.

关键词： sheet metal blank design finite element

STUDY ON ELECTRORHEOLOGICAL FLUID DAMPER FOR APPLICATION IN MACHINING CHATTER CONTROL

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Chinese Journal of Mechanical Engineering 2003年第1期16卷 13-16页

作者： Yu Junyi Zhang YongliangWang Maohua Zhou XiaoqinFaculty of Mechanical Scienceand Engineering,jilin University,Changchun 130025, China Faculty of Mechanical Scienceand Engineering Jilin University Changchun 130025

The electrorheological fluid(ERF)is a kind of intelligent material withbright prospects for industry applications, which has viscoelastic characteristic under the appliedelectric field. The dynamic model of a milling system with an ERF damper is established, and thechaffer suppression mechanism of the ER effect is discussed theoretically. Both the theoreticalstudy and the experimental investigation show that the additional damping and additional stiffnessproduced by the ERF increase with the rise in the strength of electric field E, but their influenceon the cuffing stability is different. Only when both additional damping and additional stiffnesscooperate, the milling chatter can be suppressed quickly and effectively. In additional, an ERFdamper used on the arbor of horizontal spindle milling machine is developed, and a series of millingchatter control experiments are performed. The experimental results show that the milling chaffercan be suppressed effectively by using the ER damper.

关键词： Machining chaffer ERF damper Additional damping Additional stiffness Chaffer control

Effects of Alloying Elements on Microstructure and Erosion Resistance of Fe-C-Cr Weld Surfacing Layer

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Journal of Materials Science & Technology 2003年第4期19卷 351-354页

作者： Daqian SUN, Wenquan WANG, Zhaozhi XUAN, Yue XU and Zhenfeng ZHOUSchool of Materials Science and Engineering, jilin University, Changchun 130025, China Sch. of Mat. Sci. and Eng. Jilin Univ. Changchun 130025 China

Effects of alloying elements on microstructure and erosion resistance of Fe-C-Cr weld surfacing layer have been studied. The experimental results show that increasing C and Cr content favors improving the erosion resistance of the layer, and the excessive C and Cr result in decreasing the erosion resistance at 90 deg. erosion. That Mo, Nb or Ti improves the erosion resistance of Fe-C-Cr weld surfacing layer is mainly attributed to increasing the amount of M7C3 and forming fine NbC or TiC in austenite matrix, but the excessive Mo, Nb or Ti is unfavorable. The addition of Mo, Nb and Ti in proper combination possesses stronger effect on improving the erosion resistance and the erosion resistance (εA) of Fe-C-Cr weld surfacing layer with fine NbC, TiC and M7C3 distributing uniformly in austenite matrix obviously increases to 2.81 at 15 deg. erosion and 2.88 at 90 deg. erosion when the layer composition is 3.05C, 20.58Cr, 1.88Mo, 2.00Nb and 1.05Ti (in wt pct).

关键词： Weld surfacing layer Alloying elements Erosion resistance

Progress in the bionic study on anti-adhesion and resistance reduction of terrain machines

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Science China(Technological Sciences) 2009年第2期52卷 273-284页

作者： REN LuQuanKey Laboratory for Terrain-Machine Bionics Engineering of Ministry of Education, School for Biology and Agricultural Engineering, jilin University, Changchun 130025, China Key Laboratory for Terrain-Machine Bionics Engineering of Ministry of Education School for Biology and Agricultural Engineering Jilin University Changchun China

The theoretical studies of bionics of machinery have great scientific significance, and the development of bionic machines has large practical values in the field of engineering and technology. Through the rigorous selection process of evolution, the survived living organisms have successfully developed outstanding abilities to adapt to their surroundings and to reproduce their offspring. In this review,we interpreted the fundamental principles of anti-adhesion and anti-resistance of soil animals by reviewing the current status in this research field and summarizing the work of the research group at jilin University of China in the past decades. The principles and technologies used in morphology bionics,electric-osmosis bionics,flexibility bionics,configuration bionics and coupling bionics were ***,the applications of the engineering bionics and their extensive prospects were introduced.

关键词： terrain machines anti-adhesion and anti-resistance bionics non-smooth coupling

COMPUTER AIDED ANALYSIS FOR COLD ROLL FORMING THIN CHANNEL SECTION

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Acta Metallurgica Sinica(English Letters) 2001年第2期14卷 122-126页

作者： Z. W. Han ,Y.Q. Nie, L.Q. Ren and C. Liu (Key Laboratory of Terrain Machine Bionic Technology, jilin University, Changchun 130025, China) (Mechanics Department, jilin University, Changchun 130025, China) (Institute of Rolling Mill, Yanshan University, Qin jilin Univ. Changchun 130025 China

Cold roll forming is a complicated metal processing, and its is very difficult to simulate the forming process. Based on the Updated-Lagrange method in the deformation mechanics, an elastic-plastic large deformation spline finite strip method is developed to analyze cold roll forming of a thin channel section. The longitudinal membrane strain values on the edge of the deformed strip for four one-pass sequences in different fold angles are got. Simulated results are compared with the results from previously conducted experiments. The deviation of the simulated peak strain values is within 30% compared with the experimental results.

关键词： Computer aided analysis Computer simulation Forming Mathematical models

Effects of different pack aluminizing fillers on the aluminide coatings of Ti-6Al-4V alloy and their high-temperature oxidation behaviors

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Rare Metals 2007年第S1期26卷 306-312页

作者： ZHOU Wei,ZHAO Yuguang,and MEI Xuelian Key Laboratory of Automobile Materials of Ministry of Education,Department of Materials Science and Engineering,jilin University,Changchun 130025,China jilin Univ Dept Mat Sci & Engn Key Lab Automobile Mat Minist Educ Changchun 130025 Peoples R China

The aluminide coating process of Ti-6Al-4V alloys with different fillers(100wt.% Al_2O_3,50wt% Y_2O_3+50wt.% Al_2O_3 and 100wt.% Y_2O_3) for improvement of the oxidation resistance were *** results show that the filler does not only participate in the aluminizing process,but also has much effect on the coating *** XRD analysis reveals that the aluminide coating with filler Al_2O_3 is predominant with TiAl_3 and TiAl phases;while the aluminide coatings with filler Y_2O_3+Al_2O_3 are predominant with Ti_3Al *** oxidation kinetics shows that different fillers affect greatly the oxidation resistance of aluminide coating,and the oxidation resistance of aluminized specimens with pack aluminizing filler Al_2O_3 are about 5-8 times than that of the aluminized specimens with other pack aluminizing fillers.

关键词： Ti-6Al-4V alloy aluminide coating fillers oxidation