| Combined Experimental and Computational Study of Plastic Deformation in Crystals and Bicrystals for the Development of Multi-Length Scale Constitutive Models |
28-Feb-2009 |
11 pages |
| Authors:
Jeffrey W Kysar; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING
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 | The experimental effort concentrated on wedge indentation under quasistatic conditions in single crystals of Ni, Cu, and Al as well as bicrystals of Al. Wedge indenters with included angles of 60-deg, 90-deg, and 120-deg were used in the single crystals and an included angle of 90-deg was used near the train boundary of the Al bicrystal. the lattice rotations were experimentally determined via EBSD. The experimental results were processed to ... |
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| Evaluation of Constant Temperature Control Algorithms in Modeling of Sputter-Deposited Thin Film Processes |
91 |
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| Authors:
C. C. Fang; F. Jones; V. Prasad; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING
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 | In molecular dynamics simulation of the sputter deposition of thin films, it is often required that the temperature of the deposited film be held constant. The behavior of three widely used constant temperature control algorithms, the thermal conduction method, the generalized Langevin equation, and the extended system method, is examined by depositing an energetic particle on a two-dimensional isothermal substrate made up of 768 Lennard-Jones particles. The temperature of the ... |
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| The Development of an Expert System for the Creative Design of Mechanisms |
26 JUN 89 |
114 pages |
| Authors:
Ferdinand Freudenstein; David A. Hoeltzel; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING
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| A unified design methodology has been developed for the creative design of mechanisms. This is based on an abstract representation of the kinematic structure of mechanisms, which we have called the stratified representation of mechanisms. This transforms the basic structure of a mechanism into an essentially unique spanning tree with a minimum number of edges, each associated with a fundamental loop. In this fashion hundreds of thousands of mechanisms have ... |
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| Computer-Aided Mechanisms Analysis and Design, |
FEB 1985 |
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| Authors:
F. Freudenstein; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING
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| The modern deployment of the subject of mechanisms has been influenced heavily by high-speed computation. This is due primarily to the nonlinearity, complexity and variety of the mechanical elements involved. Recent developments and research in this area will be reviewed wth emphasis on conceptual design, kinematic analysis and synthesis and dynamic analysis. (Author) |
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| The Eigenstructure Assignment of Deadbeat Control Systems |
DEC 84 |
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| Authors:
G. Klein; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING
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| All the available freedom in selecting the closed-loop Jordan block structure associated with deadbeat controllers is described and the parameters associated with this freedom are characterized. It is shown that in general one has freedom in selecting the Jordan block structure as well as the eigenvectors of deadbeat controllers. Although in general the feedback matrix is a nonlinear function of the eigenvectors that are assigned it is shown that for ... |
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| An Experimental Investigation of Molecular Rarefaction Effects in Gas Lubricated Bearings at Ultra-Low Clearances |
FEB 1981 |
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| Authors:
Y.-t. Hsia; G. A. Domoto; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING
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| The experimental investigation discussed here gives experimental confirmation of the slip-flow theory for modeling hydrodynamic gas bearings with clearances below 0.25 microns. An interferometric technique employing two CW lasers is used to measure the small clearances with an accuracy of 0.025 microns. The effects of molecular rarefaction are studied by operating the slider bearing in different gas media of different mean free paths. Bearings operating at extremely high local Knudsen ... |
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| THEORETICAL STUDIES OF DISLOCATION BEHAVIOR IN CRYSTALS. |
24 SEP 1969 |
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| Authors:
W. T. Sanders; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING
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| The ultimate objective of this study is the determination of the static and dynamic properties of dislocations and dislocation arrays through the analysis of realistic discrete (atomistic) models of crystals. An intermediate objective, and the primary goal of this program, was to gain an understanding of the possibilities and limitations of such models through the investigation of a series of simplified forms of increasing complexity. (Author) |
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| THEORETICAL STUDIES OF DEFECT MOTION IN CRYSTALS. |
27 FEB 1969 |
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| Authors:
Jerome H. Weiner; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING
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| The principal accomplishments described are: (1) A new formulation for rate processes in solids which does not make the assumption of thermal equilibrium among saddle-point configurations. (2) The extension of this formulation to include the effect of quantum statistics. (3) Development of techniques for the computer simulation of thermal equilibrium characteristics in linear-chain models of crystals containing vacancies. (Author) |
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| THREE-DIMENSIONAL ELASTICITY THEORY FOR FLAT-PLATE MEMORY ELEMENTS SUBJECTED TO SPACE-VARIABLE NORMAL TRACTION. |
JUL 1967 |
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| Authors:
H. G. Elrod; Des R. Sood; COLUMBIA UNIV NEW YORK DEPT OF MECHANICAL ENGINEERING
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| Many of the contemporary memory elements used in high-speed digital computers are flat in the unstressed state. The present work is part of a review and enlargement of applicable elasticity theory in cases of small deformation with space-variable normal traction or pressure. (1) All flat plate results are derived directly with three-dimensional linear elasticity theory - none of the conventional intermediate assumptions being employed. (2) Within the exact theory, certain ... |
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