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The　Experiment　Study　of　Two　Nd3＋：p－glass　Rods　Laser　with　a　Q－switch／mode－locking　and　Amplifier

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Chinese Journal of Lasers 1995年第3期B4卷 199-206页

作者： REN Zhaoyu ZHUANG Dounan LEI Shizhan YU Guiqiu Zhang Jiyue(Shanghai Institute of Optics and Fine mechanics, Academia Sinica,P. O. Box Shanghai 800-211,Shanghai 201800, China)(Weinan Teacher's College, Weinan 714000, Shannxi, China department of Physi Shanghai Inst of Optics and Fine Mechanics Academia Sinica Shanghai China

ＴｈｅＥｘｐｅｒｉｍｅｎｔＳｔｕｄｙｏｆＴｗｏＮｄ￣（３＋）：ｐ－ｇｌａｓｓＲｏｄｓＬａｓｅｒｗｉｔｈａＱ－ｓｗｉｔｃｈ／ｍｏｄｅ－ｌｏｃｋｉｎｇａｎｄＡｍｐｌｉｆｉｅｒ￥ＲＥＮＺｈａｏｙｕ；ＺＨＵＡＮＧＤｏｕｎａｎ... 详细信息

ＴｈｅＥｘｐｅｒｉｍｅｎｔＳｔｕｄｙｏｆＴｗｏＮｄ￣（３＋）：ｐ－ｇｌａｓｓＲｏｄｓＬａｓｅｒｗｉｔｈａＱ－ｓｗｉｔｃｈ／ｍｏｄｅ－ｌｏｃｋｉｎｇａｎｄＡｍｐｌｉｆｉｅｒ￥ＲＥＮＺｈａｏｙｕ；ＺＨＵＡＮＧＤｏｕｎａｎ；ＬＥＩＳｈｉｚｈａｎ；ＹＵＧｕｉ...

关键词： Nd: p-galss laser Q-switch mode-locking

Molecular Dynamics Simulations of Thermal Properties of Polymer Composites Enhanced by Cross-Linked Graphene Sheets

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Acta Mechanica Solida Sinica 2018年第6期31卷 673-682页

作者： Yunlong Li Shijie Wang Quan Wang School of Mechanical Engineering Shenyang University of TechnologyShenliao West Road No.111 Shenyang 110870China department of mechanics and Aerospace Engineering Southern University of Science and Technology Shenzhen 518055China

Molecular models of pristine, functionalized and cross-linked graphene sheet/polymer composites are developed. Temperature cooling processes are conducted to examine the improve-ment of glass transition temperature of cross-linked graphene sheet/polymer composites using molecular dynamics simulations. The results show that increases of about 12.2% and 8.9% in the glass transition temperature of cross-linked graphene sheet/polymer composites are obtained, respectively, than those of the pristine and functionalized graphene sheet/polymer composites. In order to reveal the enhanced thermal properties from atomic views, the interfacial interaction energy and radius distribution function between the graphene sheets and the polymer matrix, the mean square displacement variations and the free volume of polymer composites are examined and discussed.

关键词： Molecular dynamics simulation Polymer composites Graphene sheet Glass tran-sition temperature

Subset-based local *** element-based global digital image correlation:A comparison study

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Theoretical & Applied mechanics Letters 2016年第5期6卷 200-208页

作者： Bo Wang Bing Pan Institute of Solid mechanics Beihang University State Key Lab of Automotive Safety and Energy Department of Automotive EngineeringTsinghua University

Being the two primary approaches for full-field kinematics measurements, both subset-based local digital image correlation （DIC） and finite element-based global DIC have been extensively studied. Nowadays, most commercial DIC systems employ local DIC algorithm because of its advantages of straight forward principle and higher efficiency. However, several researchers argue that global DIC can provide better displacement results due to the displacement continuity constraint among adjacent elements. As such, thoroughly examining the performance of these two different DIC methods seems to be highly necessary. Here, the random errors associated with local DIC and two global DIC methods are theoretically analyzed at first. Subsequently, based on the same algorithmic details and parameters during analyses of numerical and real experiments, the performance of the different DIC approaches is fairly compared. Theoretical and experimental results reveal that local DIC outperforms its global counterpart in terms of both displacement results and computational efficiency when element （subset） size is no less than 11 pixels.

关键词： Digital image correlation Displacement measurement Finite element Subset Subpixel

QUANTIFICATION OF SHEAR DAMAGE EVOLUTION IN ALUMINIUM ALLOY 2024T3

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Acta Mechanica Solida Sinica 2007年第1期20卷 57-64页

作者： Tang Chak-yin Fan Jianping Tsui Chi-pong Lee Tai-chiu Chad Luen-chow Rao Bin department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong China School of Civil Engineering and mechanics Huazhong University Science and Technology Wuhan 430074 China

Shear damage may occur in the process of metal machining such as blanking and cutting, where localized shear deformation is developed. Experimental findings indicate that microscopic shear damage evolution in aluminium alloy 2024T3 （A1 2024T3） is a multi-stage mechanism, including particle cracking, micro-shear banding, matrix microcracking and coalescence of microcracks. This study is an attempt to use a set of equations to describe the multi-stage shear damage evolution in Al 2024T3. The shear damage variables in terms of multi-couple parameters of a power-law hardening material have been defined. An evolution curve of shearing damage has been calculated from experimental data. The values of the shear damage variable at different stages of damage have also been calculated. By making use of the findings, the relation between the microscopic shear damage evolution and the macroscopic shear response of the material has been discussed.

关键词： shear damage damage evolution equations shear band hardening material microscopic observation

RAYLEIGH-TAYLOR INSTABILITIES BY OVERTURNING EXPERIMENTS IN TANK

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Journal of Hydrodynamics 2007年第3期19卷 303-308页

作者： LI Xi CHU Vincent H. department of Ocean and Traffic Engineering Hohai University Nanjing 210098 China Deptartment of Civil Engineering and Applied mechanics McGill University Montreal H3A 2K6 Canada

A laboratory study of the turbulence front initiated by the Rayleigh-Taylor instabilities was conducted by overturning a two-layer stratified flow in a tank. Dye was introduced to the upper layer and the concentration of the dye was determined using a video imaging method. The mass center of the heavier upper layer moved continuously to a lower elevation because of the intrusion of the heavier fluid into the lower layer and the lighter fluid into the upper layer. The downward movement of the mass center was accurately determined from the dye concentration profile. It is concluded that the initial advancement of the mass center follows a quadratic relation with time and the final advancement obeys a linear relation with time.

关键词： Rayleigh-Taylor instability stratified flow turbulent mixing video imaging technique overturning experiment

PREDICTION FOR FORMING LIMIT OF AL2024T3 SHEET BASED ON DAMAGE THEORY USING FINITE ELEMENT METHOD

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Acta Mechanica Solida Sinica 2006年第2期19卷 174-180页

作者： Tang C.Y. Fan Jianping Tsui C.P. department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong China School of Civil Engineering and mechanics Huazhong University of Science and Technology Wuhan 430074 China

This paper presents the application of anisotropic damage theory to the study of forming limit diagram of A12024T3 aluminum alloy sheet. In the prediction of limiting strains of the aluminum sheet structure, a finite element cell model has been constructed. The cell model consists of two phases, the aluminum alloy matrix and the intermetallic cluster. The material behavior of the aluminum alloy matrix is described with a fully coupled elasto-plastic damage constitutive equation. The intermetallic cluster is assumed to be elastic and brittle. By varying the stretching ratio, the limiting strains of the sheet under biaxial stretching have been predicted by using the necking criterion proposed. The prediction is in good agreement with the experimental findings. Moreover, the finite element cell model can provide information for understanding the microscopic damage mechanism of the aluminum alloy. Over-estimation of the limit strains may result if the effect of material damage is ignored in the sheet metal forming study.

关键词： forming limit diagram (FLD) anisotropic damage finite element method (FEM) limit strain localized necking elasto-plastic deformation

Molecular Dynamics-Based Analysis of the Effect of Voids on Deformation of Single-Crystal CoCrFeMnNi High-Entropy Alloy

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Molecular Dynamics-Based Analysis of the Effect of Voids on ...

TRANSIENT THERMAL RESPONSE IN THICK ORTHOTROPIC HOLLOW CYLINDERS WITH FINITE LENGTH:HIGH ORDER SHELL THEORY

中国力学大会-2021+1

作者： Yuming Qi Xiuhua Chen Miaolin Feng department of Engineering mechanics State Key Laboratory of Ocean EngineeringSchool of Naval ArchitectureShanghai Jiao Tong University

Introduction/Highlight In this study,molecular dynamics is used to examine a typical single-crystal CoCrFeMnNi high-entropy alloy,and the effect of spherical void on the microstructural development of the *** different void sizes of 5?,10?and 15?,we record snapshots of microstructural changes to investigate the interaction of the alloy with these intrinsic stacking faults,and reveal the reason for the increasing material ***,by analyzing the evolution of the voids,we elucidate their effects on the deformation mechanism of the single-crystal CoCrFeMnNi high-entropy

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Acta Mechanica Solida Sinica 2010年第2期23卷 156-166页

作者： Jiaxi Zhou Zichen Deng Xiuhui Hou department of Engineering mechanics Northwestern Polytechnical University Xi'an 710072 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China

The transient thermal response of a thick orthotropic hollow cylinder with finite length is studied by a high order shell theory. The radial and axial displacements are assumed to have quadratic and cubic variations through the thickness, respectively. It is important that the radial stress is approximated by a cubic expansion satisfying the boundary conditions at the inner and outer surfaces, and the corresponding strain should be least-squares compatible with the strain derived from the strain-displacement relation. The equations of motion are derived from the integration of the equilibrium equations of stresses, which are solved by precise integration method （PIM）. Numerical results ***, and compared with FE simulations and dynamic thermo-elasticity solutions, which indicates that the high order shell theory is capable of predicting the transient thermal response of an orthotropic （or isotropic） thick hollow cylinder efficiently, and for the detonation tube of actual pulse detonation engines （PDE） heated continuously, the thermal stresses will become too large to be neglected, which are not like those in the one time experiments with very short time.

关键词： dynamic thermo-elasticity thermal response high order shell theory thick hollowcylinder

Numerical Analysis of Dry Friction-Induced Vibration of Moving Slider-Elastic Annular Beam System

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Transactions of Nanjing University of Aeronautics and Astronautics 2018年第1期35卷 84-93页

作者： Sui Xin Ding Qian department of mechanics Tianjin UniversityTianjin 300350P.R.China Tianjin Key Laboratory of Nonlinear Dynamics and Control Tianjin 300350P.R.China

A disc-pad friction system is modelled as that two moving pads act symmetrically on an annular beam with flexible boundary *** procedure is proposed to deal with the moving interactions and calculation is carried out by using the finite difference method,which shows that only the first-order mode vibration of the beam can be *** the partial differential equation of motion of the disk is reduced to a first-order mode vibration system with time-varying *** the disk speed is decreased below the critical speeds,the relative equilibrium of the pad on the disk loses its stability and stick-slip type limit cycle vibrations are resulted in all directions′*** of the disk motion on the frictional instability is also *** period of stick-slip vibration with large amplitude will be shortened with higher moving deceleration.

关键词： friction system instability stick-slip vibration Stribeck effect