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Virtual multi-dimensional internal bonds model and its application in simulation of rock mass

Science china(Technological Sciences) 2008年第2期51卷 192-201页

作者： ZHANG ZhenNan1,2 & GE XiuRun3,4 1 Department of Civil engineering,shanghai university,shanghai 200072,china 2 shanghai institute of Applied Mathematics and Mechanics,shanghai university,shanghai 200072, china 3 institute of geotechnical engineering,shanghai jiao tong university,shanghai 200030,china 4 institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,china Department of Civil engineering Shanghai University Shanghai China shanghai institute of Applied Mathematics and Mechanics Shanghai University Shanghai China institute of geotechnical engineering Shanghai Jiao Tong University Shanghai China institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan China

VMIB (virtual multi-dimensional internal bonds) is a multiscale mechanical model developed from the VIB (virtual internal bond) theory. In VIB theory,the solid mate-rial is considered to consist of random-distributed material particles in microscale. These particles are connected with normal bonds. The macro constitutive relation is derived from the cohesive law between particles. However,in VMIB,the micro particles are connected with both normal and shear bonds. The macro constitutive relation is derived in terms of bond stiffness coefficients. It has been theoretically certified that there exists a corresponding relationship between the two bond stiffness coefficients and the two macro material constants,i.e. the Young’s modulus and Poisson ratio. This corresponding relationship suggests that it should be necessary and sufficient to simultaneously account for the normal and shear interactions between particles. Due to the fact that the fracture criterion is directly incorporated into the constitutive relation,both VIB and VMIB present many advantages in simulating fractures of materials. In the damage model of rock mass,a damage tensor is usually defined to describe the distribution of cracks. The damage value in one direction determines the relative stiffness of rock mass in this direction. In VMIB solid,the relative distribution density of micro bonds in one direction determines the relative macro stiffness of the material in this direction. The effects of the damage value and the relative distribution density of bonds are consistent. To simulate the failure behavior of rock mass with VMIB,the presented paper sets up a quantitative relationship between the damage tensor and the rela-tive distribution density of bonds. Comparison of the theoretical and the experi-mental results shows that VMIB model can represent the effect of distributed cracks on rock mass with this relationship. The presented work provides a founda-tion for further simulating fracture behavior

关键词： VMIB (virtual multi-dimensional internal bonds) rock mass VIB (virtual internal bonds) multi-cracked body numerical simulation

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Experimental Study of Motion of Nitrogen Taylor Bubbles and Liquid Slugs in Inclined Tubes

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Chinese Journal of Aeronautics 2009年第4期22卷 349-354页

作者： Zhang Hua,Wang Shuhua,Wang Jing institute of engineering Thermo-physics,shanghai jiao tong university,shanghai 200240,china institute of engineering Thermo-physics Shanghai Jiao Tong University Shanghai 200240 China

This article studies rising velocity of Taylor bubbles and liquid slugs in liquid nitrogen at different axial positions in upward inclined tubes by means of a high speed motion analyzer. The bottom-closed tubes in the experiments are 1.0 m long with an inner diameter of 0.014 m or 0.018 m. The tube inclines upward from 0~ to 50~ with respect to the normal. Statistical method is used to analyze the data of the Taylor bubble and the liquid slug velocity. Reflecting the effects of the inclination angle on the rising velocity of Taylor bubbles and liquid slugs, the experimental results indicate the similar trend the Taylor bubble velocity and the liquid slug velocity have： it increases first, and then decreases with the increase of the inclination angle. Moreover, with the increase of the inclination angle, the liquid slug velocity becomes greater than Taylor bubble velocity.

关键词： cryogenic two-phase flow rising velocity high speed motion analyzer liquid nitrogen Taylor bubble liquid slug inclined tube

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WATER TUNNEL EXPERIMENTAL INVESTIGATION ON THE DRAG REDUCTION CHARACTERISTICS OF THE TRAVELING WAVY WALL

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Journal of Hydrodynamics 2011年第1期23卷 65-70页

作者： YAO Yan LU Chuan-jing SI Ting ZHU Kun Department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China Beijing Electromechanic engineering institute Beijing 100074 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China Department of modem Mechanics University of Science and Technology of China Hefei 230027 China

Drag reduction experiment of the traveling wavy wall at high Reynolds number is conducted.A suit of traveling wavy wall device is *** drag forces of the traveling wavy wall with various wave speeds（c）are measured under different water speeds（U）in the K15 cavitation water tunnel and are compared with that of the flat *** results show that the mean drag force of the traveling wavy wall have decreased and then increased with oscillation frequency increasing at the same flow *** different flow speeds,when traveling wave wall reached to the minimum of drag force,the corresponding the ratio of the wall motion phase speed c to flow speed U,c /U is slightly *** the parameters of the experiment,whenc /U reaches a certain value,the drag force of the traveling wavy wall can be less than that of the flat *** drag reduction can be up to 42%.Furthermore,as the value ofc /U increases,the traveling wavy wall can restrain the separation and improve the quality of flow field.

关键词： flow control drag reduction traveling wavy wall water tunnel test

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EXPERIMENTAL INVESTIGATION ON THE DRAG REDUCTION CHARACTERISTICS OF TRAVELING WAVY WALL AT HIGH REYNOLDS NUMBER IN WIND TUNNEL

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Journal of Hydrodynamics 2010年第5期22卷 719-724页

作者： YAO Yan LU Chuan-jing SI Ting ZHU Kun Department of engineering Mechanics Shanghai Jiao Tong University Shanghai 200240 China Beijing Electromechanic engineering institute Beijing 100074 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China Department of Modern Mechanics University of Science and Technology of China Hefei 230027 China

Drag reduction experiments of the traveling wavy wall at high Reynolds number, ranging from 1.46×106 to 5.83×106 based on the free-stream velocity and the model length, were conducted. A suit of traveling wavy wall device was developed and its characteristics of drag reduction at high Reynolds number were investigated. The drag forces of the traveling wavy wall with various wave speeds （ c ） were measured at different wind speeds （U ） in the FL-8 low-speed wind tunnel and compared with the drag force of the flat plate. The results show that the mean drag force of the traveling wavy wall decreases as the value of c /U increases, at different wind velocities, the values of c /U corresponding to minimal drag force of the traveling wavy wall are different, when the values of c /U are larger than 0.6, the mean drag forces of the traveling wavy wall are smaller than those of the flat plate, and the drag reduction can be up to 60%. The drag reduction effectiveness of traveling wavy wall is thus achieved. Furthermore, as the value of c /U increases, the traveling wavy wall can restrain the separation and improve the quality of flow field.

关键词： flow control drag reduction traveling wavy wall wind tunnel test

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Induced electromagnetic stirring behavior in a resistance spot weld nugget

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Science china(Technological Sciences) 2010年第5期53卷 1271-1277页

作者： LI YongBing1,LIN ZhongQin1,2,LAI XinMin1,2,CHEN GuanLong1,2 & ZHANG Ke3 1 shanghai Key Laboratory of Digital Autobody engineering,shanghai jiao tong university,shanghai 200240,china 2 State Key Laboratory of Mechanical System and Vibration,shanghai jiao tong university,shanghai 200240,china 3 Welding engineering institute,shanghai jiao tong university,shanghai 200240,china shanghai Key Laboratory of Digital Autobody engineering Shanghai Jiao Tong University Shanghai China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai China Welding engineering institute Shanghai Jiao Tong University Shanghai China

A multi-physics hybrid numerical model,which couples electric,magnetic,thermal and flow fields,was used to investigate electromagnetic stirring behavior in a resistance spot weld *** differences of two kinds of different excitation inputs,i.e.,a sinusoidal current and its root-mean-square(RMS) value,were studied to examine if they could produce equivalent electromagnetic stirring effects in the weld *** showed that the two types of current inputs could produce almost identical fluid flow and heat transfer patterns and consistent evolution of flow and thermal fields in the *** the end of the welding cycles,the maximum flow velocity and temperature between the two inputs differed by 11.6% and 0.3%,***,the RMS current can be assumed to produce an approximately equivalent electromagnetic stirring effect with the sinusoidal current,and can be used in the future research to greatly improve the solution efficiency of the electromagnetic stirring behavior in the resistance spot weld nugget.

关键词： induced magnetic field electromagnetic stirring resistance spot welding fluid flow heat transfer

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NUMERICAL INVESTIGATION ON THE AEROELASTIC BEHAVIOR OF AN AIRSHIP WITH HULL-FIN CONFIGURATION

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Journal of Hydrodynamics 2010年第2期22卷 207-213页

作者： LIU Jian-min LU Chuan-jing - XUE Lei-ping Marine engineering institute Jimei University Xiamen 361021 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China

Numerical investigation was conducted on an airship of hull-fin configuration for aerodynamic and aeroelastic characteristics in three-dimensional viscous *** mathematical model was built and the corresponding numerical code was developed for the fluid-structure interaction *** governing equations of the viscous flow with LL-Low Reynolds modified model were solved by the standard SIMPLE algorithm based on the finite volume method.A fluid-structure coupled method was employed to solve the nonlinear aeroelasticity problem for the *** computational results of the viscous flow are in good agreement with the experimental *** simulation on the aeroelastic behavior of the airship in a trimmed flight reveals the effect of structure flexibility on the aerodynamic performance.

关键词： fluid-structure interaction airship aeroelasticity flexibility

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RESEARCH ON MEASURING METHOD OF THE THERMALCONDUCTIVITY FOR HIGHLY POROUS MATERIALS

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Acta Metallurgica Sinica(English Letters) 1997年第3期10卷 213-218页

作者： J Y Wu Z.M. Tang W Shi andR.Z. Wang (institute of Refrigeration and Cryogenics engineering, shanghai jiao tong university, shanghai 200030,china) shanghai jiaotong Univ Shanghai China

A transient method with rectangular pulse heating has been developed to measure the thermal conductivity of highly porous materials such as activated carbon, zeolite and silica gel. By this method the thermal conductivity can be measured quickly and accu-rately. In this paper, a set of automatically controlled testing equiptnent is *** measuring method is analysed. The thermal conductivities of some samples, such as activated carbon and zeolite, are measured by the equipment. A group of useful data has been obtained.

关键词： thermal conductivity porous material thermophysical property

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NUMERICAL SIMULATION OF TRANSIENT FLOW AROUND A SHIP IN UNSTEADY BERTHING MOTION

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Journal of Hydrodynamics 2009年第3期21卷 379-385页

作者： WANG Hua-ming ZOU Zao-jian TIAN Xi-min School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 China School of Naval Architecture Ocean and Civil Engineering Shanghai Jiao Tong University Shanghai 200240 State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China Marine Design and Research institute of china Shanghai 200011 China

Ship berthing is a specific maneuver operation. The flow around a berthing ship and the forces acting on the hull are quite different from those for a ship in normal navigation. By solving the unsteady Reynolds-Averaged Navier-Stokes （RANS） equations, the transient flow field around a ship undergoing unsteady lateral motion is simulated and the varying lateral hydrodynamic force acting on the hull is evaluated in this article. The numerical results obtained with different turbulence models are analyzed and compared with experimental results and other numerical results published in literature, and a turbulence model more suitable for simulation of the viscous flow around a ship undergoing unsteady berthing is determined.

关键词： ship berthing transient flow lateral hydrodynamic force numerical simulation

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AN OPTIMIZATION OF EIGENFUNCTION EXPANSION METHOD FOR THE INTERACTION OF WATER WAVES WITH AN ELASTIC PLATE

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Journal of Hydrodynamics 2009年第4期21卷 526-530页

作者： XU Feng LU Dong-qiang shanghai institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China State Key Laboratory of Ocean engineering Shanghai Jiao Tong University Shanghai 200030 China

The hydroelastic interaction of an incident wave with a semi-infinite horizontal elastic plate floating on a homogenous fluid of finite depth is analyzed using the eigenfunction expansion method. The fluid is assumed to be inviscid and incompressible and the wave amplitudes are assumed to be small. A two-dimensional problem is formulated within the framework of linear potential theory. The fluid domain is divided into two regions, namely an open water region and a plate-covered region. In this paper, the orthogonality property of eigenfunctions in the open water region is used to obtain the set of simultaneous equations for the expansion coefficients of the velocity potentials and the edge conditions are included as a part of the equation system. The results indicate that the thickness and the density of plate have almost no influence on the reflection and transmission coefficients. Numerical analysis shows that the method proposed here is effective and has higher convergence than the previous results.

关键词： wave scattering eigenfunction expansion method orthogonality

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An improved approach to the efficient construction of and search operations in motion graphs

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Science china(Information Sciences) 2012年第5期55卷 1042-1051页

作者： GAO Yan 1,CHEN ZhiHua 2,CHEN MinGang 3 & SHEN Yang 3 1 Software engineering institute,East china Normal university,shanghai 200062,china 2 Department of Computer Science and engineering,East china university of Science and Technology,shanghai 200237,china 3 Department of Computer Science and engineering,shanghai jiao tong university,shanghai 200240,china Software engineering institute East China Normal University Shanghai China Department of Computer Science and engineering East China University of Science and Technology Shanghai China Department of Computer Science and engineering Shanghai Jiao Tong University Shanghai China

Motion graphs have been widely used as an effective technique in the synthesis of human *** synthesize well-formed motions,motion graphs require smooth transitions and good ***,the time and costs grow quadratically as the graph size *** this paper,we present a method to set up a hierarchical structure,called a structure *** coarse level of this graph models different motion categories and their transitions,and the fine level mainly captures different motion *** interpolation space method is used to improve the graph connectivity at the fine *** structure guides the establishment of a faster and more realistic graphical *** the building process,this structure also helps with searching the motion graph,by performing a traverse search and placing the findings into a direct look-up table or local search ***,when there is no direct link between the different motions,a navigation map is introduced to conduct an appropriate search path via a series of transition motion *** experimental results indicate that our approach could lower the computation time in construction and searching,while simultaneously providing a richer variety of motion styles.

关键词： motion graph structure table registration curve motion interpolation

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