| Phononics and Micromechanics of Bio-Colloidal Wiseana Iridovirus |
Aug-2008 |
3 pages |
| Authors:
Sangwook Sihn; Huiming Xiong; Ryan D Hartschuh; Stephen P Wargacki; Johnathan Neiswinger; Alexander Kisliuk; Vernon K Ward; Richard A Vaia; Alexei P Sokolov; AKRON UNIV OH INST OF POLYMER SCIENCE
|
 | By using Brillouin Light Scattering (BLS), we have investigated phononic properties of Wiseana iridovirus (WIV) assemblies and dispersed individual viruses at hypersonic frequency window. Propagating modes in virus assemblies and localized vibrational eigenmodes of individual virus have been identified. Based on phonon spectra, Young's modulus of the virus has been estimated to be 7 GPa, suggesting that the WIV virions are mechanically more similar to their DNA cores than to ... |
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| System Analysis and Design of a Low-Cost Micromechanical Seeker System |
JUN 2008 |
|
| Authors:
Brian J. Nagle; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
 | Precision guided targeting systems have been in use by the U.S. military for the last half-century. The desire for high targeting accuracies while maintaining minimal collateral damage has driven the implementation of guidance systems on a myriad of different platforms. Current seeker systems using global positioning system (GPS)-aided technology offer good accuracy, but are limited by an adversary's signal jamming capabilities and the dynamic nature of the military target environment. ... |
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| MEANS 2: Microstructure-and Micromechanism-Sensitive Property Models for Advanced Turbine Disk and Blade Systems |
24 APR 2008 |
8 pages |
| Authors:
Kevin J. Hemker; JOHN HOPKINS UNIV BETHESDA MD OPERATIONS RESEARCH OFFICE
|
| The overall coordinated research effort involved activities in the following areas: (1) Creep and Deformation Structure Characterization Studies of Disk Alloy Rene 104 (ME3), (2) Calculation of Activation Barriers Using Phase Field Dislocation Dynamics, (3) Adaptive computational model of crystal plasticity involving micro-twinning, (4) 3D Atom Probe Analysis of Phase Microstructures. Descriptions of all activities can be found in the annual and final reports submitted and to be submitted by ... |
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| Generation of High Frequency P and S Wave Energy by Rock Fracture During a Buried Explosion |
10 NOV 2007 |
32 pages |
| Authors:
Charles G. Sammis; CALIFORNIA UNIV LOS ANGELES DEPT OF EARTH AND SPACE SCIENCES
|
| The micromechanical damage mechanics developed by Ashby and Sammis (1990) was used to explore the effects of rock fracture on the seismic coupling of explosions. An important focus was the effect of ice in the fractures. The main effect of ice in the cracks of crystalline rock is to bridge the existing cracks forming a larger number of smaller cracks. Ice also increases the coefficient of friction on the cracks ... |
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| Finite Element Solution: Nonlinear Flapping Beams for Use with Micro Air Vehicle Design |
MAR 2007 |
122 pages |
| Authors:
Robert L. Walker; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The development and use of Micro Air Vehicles is becoming more and more important to the military. Size, weight, maneuverability, stealth, and fuel consumption are just some of the constraints on a future Micro Air Vehicle. Perfect blueprints for a small scale flying machine are both insects and humming birds. Medium sized hummingbirds are found to have wings-beats at a frequency of 18-28 Hz. There is a vast amount of ... |
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| Experimental Micromechanics Study of Lamellar TiA1 |
15 FEB 2007 |
25 pages |
| Authors:
Fu-Pen Chiang; STATE UNIV OF NEW YORK AT STONY BROOK DEPT OF MECHANICAL ENGINEERING
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| A unique micro-scale full field deformation measurement technique called electron speckle photography is exploited to investigate the deformation mechanism of lamellar TiAl. We find the size of the specimen used and the area of strain measurement affect the mechanical properties thus obtained. The strain distribution inside a grain is highly heterogeneous. The grain boundary is much stiffer than the interior of the grain. We also observe several interesting phenomena of ... |
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| Micromechanics of Smart Materials for Large Deployable Mirrors |
10 NOV 2006 |
17 pages |
| Authors:
Arup K. Maji; NEW MEXICO UNIV ALBUQUERQUE DEPT OF CIVIL ENGINEERING
|
| The objective of this research was to investigate the micro-mechanical behavior of a new type of smart material that could enable the accurate deployment of large sensors and structures in space, Elastic Memory Composites (EMC). The basic science aspect of this study involved understanding how the properties of the constituents (matrix and fiber) affect the deployment rate, deployment accuracy and failure of these smart composites. The experimental program and analytical ... |
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| Micromechanics and Microstructure Evolution: Modeling, Simulation and Experiments. Conference Held in Madrid, Spain, 12-16 Sep 2005 |
30 OCT 2006 |
95 pages |
| Authors:
UNIVERSIDAD POLITECNICA DE MADRID (SPAIN)
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| The aim of this conference is to bring together scientists who are working on the modeling and simulation of the deformation behavior of materials and on material microstructural evolution. The focus will be on the interplay between behaviors at different length scales in particular the atomistic nano/mesoscales and continuum aspects necessary to describe the processes that lead to changes in microstructure. Of particular interest are investigations that discuss the bridging ... |
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| Comparative Studies of the Performance of High-Speed Gas Bearings for Micro-Turbo Machines |
20 FEB 2006 |
53 pages |
| Authors:
Shin-ichi Togo; TOHOKU GAKUIN UNIV SENDAI (JAPAN) DEPT OF MECHANICAL ENGINEERING
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| Developed micromachine gas turbine generator for robotics & man-portable power sources operation at ultra-high speed (870,000rpm for 10mm compressor). Developed Hydrodynamic Herringbone/Spiral groove bearing to reach design speed and completed test on performance. |
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| The Design of Accurate Micro-Compression Experiments |
2006 |
12 pages |
| Authors:
Haitao Zhang; Brian E. Schuster; Qiuming Wei; Kaliat T. Ramesh; JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICAL ENGINEERING
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| We investigate (via finite-element analyses) the factors that may affect the accuracy of micro-compression measurements. Based on these simulations, we suggest guidelines for the development of accurate micro-compression experiments in terms of fillet to post radius ratio, post aspect ratio, post taper, and system alignment. |
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| Micro-mechanics of fiber reinforced bounded and unbounded solids: effective local and non-local thermo-elastic properties, stress concentration factors, and edge effect |
Jul-2005 |
282 pages |
| Authors:
Maslov B Petrovich; NATIONAL ACADEMY OF SCIENCES KHARKOV(UKRAINE) S P TIMOSHENKO INST OF MECHANICS
|
| Initiation of failure in a composite specimen can be related to the non-linear elastic stress field present in constituents. More often one examines the distribution of extreme values for the stress in the elastic inclusion's coatings. Inclusion-reinforced materials are the objects of the investigations of the P-1 10 project. The early analysis work on the damage of the composites has used linear elastic mechanics so it has been less successful ... |
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| Micromechanical Analysis of Three-Dimensional Open-Cell Foams Using the Matrix Method for Space Frame Structures |
NOV 2004 |
14 pages |
| Authors:
A. K. Roy; K. Li; X. L. Gao; MICHIGAN TECHNOLOGICAL UNIV HOUGHTON DEPT OF MECHANICAL ENGINEERING AND ENGINEERING MECHANICS
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| A micromechanical model for three-dimensional open-cell foams is developed by using the matrix method for space frames in structural mechanics and tetrakaidcahedral unit cells. The effective elastic properties of foams are determined employing unit cells subjected to three different modes of loading. The thirty-six struts of each tetrakaidecahedral unit cell are treated as uniform slender beams, and the twenty-four vertices as rigid joints. All four- deformation mechanisms (i.e., stretching, shearing, ... |
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| A Micromechanical Model for Slit Damaged Braided Fabric Air-Beams |
18 MAY 2004 |
18 pages |
| Authors:
John N. Rossettos; NORTHEASTERN UNIV BOSTON MA DEPT OF MECHANICAL ENGINEERING
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| A micromechanical model has been developed that will allow the study of a slit-damaged braided fabric air-beam structure. As such, the relevant system of non- dimensional ordinary differential equations are derived and solutions are given for the stress concentration near the broken yarns. This knowledge will contribute to the prediction of damage growth and the ability to compare different fabric materials for their damage tolerance. A simplification of the analysis ... |
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| Micromechanics Study of a Polymer with/without Microparticles |
01 MAR 2004 |
8 pages |
| Authors:
Sheng Chang; Chi Tsieh Liu; Fu-Pen Chiang; AIR FORCE RESEARCH LAB EDWARDS AFB CA SPACE AND MISSILE PROPULSION DIV
|
| SIEM (Speckle Interferometry with Electron Microscopy) is a micro/ nano experimental mechanics technique that is able to perform the full field displacement mapping over a region of only several microns in size. In this study we tested specimens made of a pure binder material, a polymer, and binder material mixed with 6 micron aluminum particles under uniaxial tension. The binder material with microparticles was made by adding 10% by weight ... |
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| Toward Generalized Continuum Models of Granular Soil and Soil-Tire Interaction |
31 JAN 2004 |
14 pages |
| Authors:
Antoinette Tordesillas; MELBOURNE UNIV VICTORIA (AUSTRALIA) DEPT OF MATHEMATICS AND STATISTICS
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| This report summarizes accomplishments from Phase 3, the objectives of which were as follows: (1) the refinement and evaluation of the constitutive models, and (2) the implementation of these models using the finite element method to the classical flat punch problem. The authors' micromechanical approach has delivered the first breed of enriched continuum models for granular media, with a resolution high enough to capture internal microstructures that are only a ... |
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| The Design and Control of Smart Structures |
JAN 2004 |
23 pages |
| Authors:
Roger W. Brockett; P. S. Krishnaprasad; John Baillieul; HARVARD UNIV CAMBRIDGE MA
|
| This is the final report of the Boston University, Harvard University and University of Maryland MURI on Design and Control of Smart Structures. The report contains a summary of results obtained from the inception of the program in May 1997 until its conclusion in August, 2003. Over this period the researchers involved produced new and useful results in the areas of micromechanical devices (fabricated and used at ARL), micro fluidics, ... |
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| Shell-Type Micromechanical Actuator and Resonator |
02 SEP 2003 |
4 pages |
| Authors:
Maxim Zalalutdinov; Keith L. Aubin; Robert B. Reichenbach; Alan T. Zehnder; Brian Houston; Jeevak M. Parpia; Harold G. Craighead; CORNELL UNIV ITHACA NY
|
| Dome-shaped radio-frequency micromechanical resonators were fabricated by utilizing the buckling of a prestressed thin polysilicon film. The enhanced rigidity of the dome structure leads to a significant increase of its resonant frequency compared to a flat plate resonator. The shell-type geometry of the structure also provides an imbedded actuation mechanism. Significant out-of plane deflections are actuated by mechanical stress introduced within the plane of the shell. We demonstrate that thermomechanical ... |
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| Frequency Entrainment for Micromechanical Oscillator |
18 AUG 2003 |
4 pages |
| Authors:
M. Zalalutdinov; K. L. Aubin; M. Pandey; A. T. Zehnder; R. H. Rand; H. G. Craighead; B. H. Houston; CORNELL UNIV ITHACA NY
|
| We demonstrate synchronization of laser-induced self-sustained vibrations of radio-frequency micromechanical resonators by applying a small pilot signal either as an inertial drive at the natural frequency of the resonator or by modulating the stiffness of the oscillator at double the natural frequency. By sweeping the pilot signal frequency, we demonstrate that the entrainment zone is hysteretic and can be as wide as 4% of the natural frequency of the resonator, ... |
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| Nanolaminates and Microlaminates: Modeling and Characterization |
06 AUG 2003 |
6 pages |
| Authors:
Iwona Jasiuk; W. J. Lackey; GEORGIA INST OF TECH ATLANTA SCHOOL OFMECHANICAL ENGINEERING
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| The author fabricated C/SiC laminates with layer thicknesses spanning two length scales (micrometer and nanometer) and fabricated particle-reinforced composites consisting of particles (cobalt and SiC) and polymer matrix (polysterene and epoxy) with particle diameters spanning these two scales. The laminates were made using the laser vapor deposition technique, while the particle-reinforced composites were made using either polymer synthesis or a resin transfer molding technique. The author characterized the ultrastructures of ... |
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| Aerospace Composite Materials: Delivery Order 0002: Development and Validation of Micromechanical Models for Composites |
MAR 2002 |
167 pages |
| Authors:
V. Buryachenko; E. Iarve; R. Kim; S. Sihn; G. P. Tandon; DAYTON UNIV OH RESEARCH INST
|
| Mechanics modeling and verification of a variety of systems continues to be examined. Systems successfully examined include the single filament cruciform test, identification of failure modes in composites, woven fabric composite, carbon foams, the fiber pushout test, and slanted free-edge plies. Techniques used include concentric cylinder modeling, finite element method, B- spline approximation, and in situ observation of damage during testing via scanning electron microscopy (SEM). The iteration method was ... |
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| Predicting the Initial Crack Length in a Solid Propellant |
20 OCT 2000 |
3 pages |
| Authors:
C. T. Liu; Y. W. Kwon; T. L. Hendrickson; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| In this study, a micro-macromechanical approach was used to predict the initial crack length near the edge of the hole in solid propellant specimens. The approach was based on a simplified micromechanical model, damage mechanics at the micro-level, and finite element analysis at the macro-level. Both micromechanical and macromechanical analyses were conducted in tandem. The developed technique together with a mechanistic criterion was used to predict the initial crack length ... |
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| Research Equipment for Damage Characterization in Structural Solids |
09 OCT 2000 |
16 pages |
| Authors:
Ajit K. Mal; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| (1) Theoretical modeling of some of the problems associated with the above described topics presented a challenge. The complex nature of the geometry as well as the materials involved precluded the application of purely analytical methods for their solution. We were able to use conventional BEM for topic #2 and a hybrid form of the FEM for topic//4, but these methods did not work well for the ... |
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| MURI IPD Introduction and Project Overview |
14 AUG 2000 |
27 pages |
| Authors:
David L. Hall; Carl S. Byington; PENNSYLVANIA STATE UNIV UNIVERSITY PARK
|
| Developed a formalization of CBM technology and engineering. Established test beds, tools, and processes for CBM. Created new methods for observing, detecting, and characterizing mechanical failures. new architectures and methods for automated reasoning. Developed new mathematical formulations and models for failure prediction. Demonstrated viability of hierarchical machinery prognostics. Established enabling technology for CBM transition and implementation using a open system architecture. S&T base of data, models, tools, and training material ... |
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| A Large Deformation Finite Element Analysis of Soil-Tire Interaction Based on the Contact Mechanics Theory of Rolling and/or Sliding Bodies |
30 JUN 2000 |
10 pages |
| Authors:
Antoinette Tordesillas; MELBOURNE UNIV PARKVILLE (AUSTRALIA)
|
| This research program is aimed at the development of a soil-tire interaction model based on Contact Mechanics Theory. The model developed obviates the need for a priori knowledge of soil-tire contact properties and instead relies on directly and accurately measurable quantities. Other major research outcomes of this program include: 1) the first complete solution to the frictional contact problem between a granular material and a deformable ... |
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| High Temperature Micromechanics and Mechanisms of Damage and Failure in Advanced Ceramic-Matrix Composites |
28 JUN 2000 |
114 pages |
| Authors:
S. S. Wang; HOUSTON UNIV TX
|
| In this project, research efforts have been made to address some of the most critical and complex issues on high-temperature damage, degradation and failure of advanced composites. For the convenience of program planning and execution, the research as been formulated in the form of several interrelated technical tasks with distinct focuses. In the study of high-temperature ceramic- matrix the following tasks have been conducted: (1) High-temperature fiber/ ... |
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| Micromechanical Study of Interface Stress in a Fiber-Reinforced Composite under Transverse Loading Using Boundary Element Method |
MAR 2000 |
90 pages |
| Authors:
Hakan Eren; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Composite materials are involving in engineering applications at a growing speed, due to their stiffer, stronger and lighter properties. This growth requires fast and powerful numerical methods like Boundary Element Method (BEM), and Finite Element Method (FEM). BEM has become popular especially in the last decade due to its advantage of requiring less computation time for the same accuracy. The objective of this study is, by using Boundary ... |
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| Micromechanical Modeling of Superplastic Materials |
21 SEP 1999 |
127 pages |
| Authors:
Namas Chandra; FLORIDA AGRICULTURAL AND MECHANICAL UNIV TALLAHASSEE
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| In this work, superplastic deformation were studied at atomistic, mesoscopic and macroscopic levels with a special focus on the former two. At the atomistic level, we studied the energy and structure of symmetric tilt boundaries and examined the energy barriers during grain boundary sliding of Aluminum bicrystal. We also studied the effect of temperature and impurity atoms on the structure, energy and deformation of grain boundary sliding. ... |
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| Development of a Micromechanic Theory of Crack Initiation Under High- Cycle Fatigue |
20 SEP 1999 |
100 pages |
| Authors:
T. H. Lin; CALIFORNIA UNIV LOS ANGELES
|
| From the hint provided by extrusion and intrusion in fatigue specimen, a micromechanic model consisting of a thin slice R sandwiched in two thin slices P and Q is developed. P with positive initial shear stress slides forward in the forward loading, while the other Q with negative initial shear stress slides backward during the reversed loading. Micromechanic analysis shows that the positive slip in P relieves the positive shear ... |
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| A Basic Research Program for the Characterization of the Mechanical Behavior of Textile-Type Composites |
14 JUN 1999 |
113 pages |
| Authors:
Adnan H. Nayfeh; CINCINNATI UNIV OH DEPT OF AEROSPACE ENGINEERING AND ENGINEERING MECHANICS
|
| A micromechanical model is advanced in order to study the stress transfer and associated damage and failure in classes of conventional and textile type fibrous composites. Unidirectionally reinforced matrix with straight and undulated fibers define the repeating constructing cell for conventional and textile composites, respectively. Starting with the case of straight reinforcement, we approximate and model the actual discrete composite as a concentric cylindrical system. For axisymmetric loading, and upon ... |
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| Micromechanics of Anisotropic Solids with Defects and Inhomogeneities |
OCT 1998 |
8 pages |
| Authors:
Mark Kachanov; TUFTS UNIV MEDFORD MA DEPT OF MECHANICAL ENGINEERING
|
| The research effort was focused on the mechanics of anisotropic solids with multiple cracks and pores. The most general case of arbitrary oriented and interacting defects was investigated. The following basic aspects of the problem were addressed: (1) the influence of anisotropy of the matrix on the mechanics of crack interactions; (2) effective elastic properties of anisotropic materials with multiple cracks; (3) mechanics of crack-microcrack interactions; and (4) mechanics of ... |
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| FIDEP2 User Manual to Micromechanical Models for Thermoviscoplastic Behavior of Metal Matrix Composites |
SEP 1998 |
246 pages |
| Authors:
Demirkan Coker; Frank Boller; Joseph Kroupa; Noel E. Ashbaugh; DAYTON UNIV OH RESEARCH INST
|
| The FIDEP2 (Finite-Difference code for Elastic-viscoplastic analysis) is a PC-compatible, user-friendly computer code developed in-house at the Materials Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio. The program is capable of predicting micromechanical stresses in metal matrix composites under complex thermal and mechanical loading histories. The FIDEP2 is a generalized version of the FIDEP program, which was limited by the concentric cylindrical geometry and elastic-plastic constitutive model. The FIDEP2 program ... |
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| A Micromechanical Investigation of Instability in Particulate Materials and Higher Order Continuum Theory Assumptions |
31 AUG 1998 |
134 pages |
| Authors:
Jean-Pierr Bardet; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF CIVIL ENGINEERING
|
| The micropolar theory (Eringen, 1966, 1968) is a continuum version of the structural theory of Cosserat (1909). It enriches the kinematics and kinetics of continua by adding material rotations and couple stresses. Using a micropolar approach similar to Kanatani (1979), Muhlhaus and Vardoulakis (1986) explained the emergence, orientation and thickness of shear bands in granular materials. Bardet and Proubet (l992a) used a similar linear stability analysis and micropolar description, and ... |
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| Mathematical Problems in Micromechanics and Composite Materials |
12 AUG 1998 |
14 pages |
| Authors:
Robert V. Kohn; Marco Avellaneda; NEW YORK UNIV NY COURANT INST OF MATHEMATICAL SCIENCES
|
| This is the final technical report on ARO contract DAAH04-95-1-0100, which began March 1, 1995 and ended June 30, 1998. This project's scientific focus was at the frontier where mathematics meets materials science. Physically, it was concerned with issues such as the effective behavior of composites and the formation of microstructure due to coherent phase transformation. Mathematically, it brought to bear a variety of tools including homogenization, the calculus of ... |
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| Micromechanics of Inelastic Composite Materials |
1998 |
29 pages |
| Authors:
RENSSELAER POLYTECHNIC INST TROY NY
|
| Under these circumstances, it fs essential to develop micromechanical theories which evaluate the local fields and predict the overall response under combined thermal and mechanical loads. The basic elements of these theories are geometrical modeling of the microstructures and local interactions, and constitutive modeling of the homogeneous phases. An essential requirement of the latter is to include inelastic deformation to model composite systems which exhibit nonlinear response under thermal and ... |
|
| Micro-Electromechanical Switches for Micro-Satellite Power Transfer |
DEC 97 |
108 pages |
| Authors:
Glen A. Kading; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH SCHOOL OF ENGINEERING
|
| In the past few years, microelectromechanical systems (MEMS) have emerged as a promising new technology with tremendous application potential. One of the possible implementations of MEMS technology is in the development of micro-satellites. It should be possible to mass-produce micro-satellites at a fraction of the cost of one conventional satellite. In order for satellites to be robust, a method of transferring power to systems must be addressed. As micro-satellites are ... |
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| Silicon-Micro-Disk Arrays for Data Storage |
30 SEP 97 |
7 pages |
| Authors:
L. Richard Carley; Gary Fedder; CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF ELECTRICAL AND COMPUTER ENGINEERING
|
| We envision arrays of silicon disk drives which are completely manufactured by planar lithographic techniques that can vastly decrease the size, weight, power requirements, cost, latency of access, and failure rate, of data storage systems. In this project we have demonstrated MEMS actuators that achieve greater than or equal 1% swept area. To achieve this goal, we have developed a custom MEMS process that starts with a standard CMOS foundry. ... |
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| Mechanism-Based Design of Composite Structures. Volume I: Executive Summary |
AUG 97 |
314 pages |
| Authors:
George J. Dvorak; RENSSELAER POLYTECHNIC INST TROY NY
|
| Final results obtained on the Mechanism-Based Design of Composite Structures Program at Rensselaer Polytechnic Institute, are described in three volumes. Volume one contains the Executive Summary and reprints of papers on Micromechanics and Computer-Aided Design Tools. Volume two is a continuation of reprints of papers on Micromechanics and Computer-Aided Design Tools. The third Volume contains reprints of papers on Processing and Performance. |
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| Mechanics of Brittle-Matrix Composites |
AUG 1997 |
58 pages |
| Authors:
Ran Y. Kim; DAYTON UNIV OH RESEARCH INST
|
| Model brittle matrix composites (SiC fibers and borosilicate glass) demonstrated that good matrix cracking stress is achievable only when a good matrix interfacial bond exists. Improvement in this matrix cracking stress can be seen with increasing fiber volume and lowered radial residual compressive stress. The ability to measure the fiber-matrix normal interfacial strength in a composite was demonstrated using a model system in a cruciform sample geometry. An analytical model ... |
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| Mechanism-Based Design of Composite Structures. Volume II: Research Papers on Micromechanics and Computer-Aided Design Tools |
AUG 97 |
512 pages |
| Authors:
George J. Dvorak; RENSSELAER POLYTECHNIC INST TROY NY
|
| Final results obtained on the Mechanism-Based Design of Composite Structures Program at Rensselaer Polytechnic Institute, are described in three volumes. Volume one contains the Executive Summary and reprints of papers on Micromechanics and Computer-Aided Design Tools. Volume two is a continuation of reprints of papers on Micromechanics and Computer-Aided Design Tools. The third Volume contains reprints of papers on Processing and Performance. |
|
| Application of Micro Electro-Mechanical Sensors and Activators in the Investigation of Supersonic Jet Screech |
30 JUL 97 |
14 pages |
| Authors:
Hassan Nagib; Joe Papp; Ahmed Naguib; ILLINOIS INST OF TECH CHICAGO FLUID DYNAMICS RESEARCH CENTER
|
| An investigation aimed at examining the usability of MEMS based actuators for controlling supersonic jet screech has been conducted. First, documentation of the screech phenomenon in the newly constructed high speed jet facility (HSJF) at IIT has been completed. Results from microphone measurements complemented with earlier shadowgraph and schlieren visualization have shown that the screech characteristics in the HSJF conforms with that published in the literature. Second, detailed investigation of ... |
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| Unique Aspects of Micromechanics in Ballistic Penetration |
JUL 97 |
38 pages |
| Authors:
P. W. Kingman; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Ballistic experiments with tungsten penetrators composed of single crystals have been used to specify and constrain deformation modes in order to elucidate the role of flow and deformation mechanisms in penetration. The large differences in penetrator performance as a function of crystal symmetry are interpreted in terms of the structures observed and the basic deformation modes implied. The results suggest in very general terms the interactive role a material deformation ... |
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| The Micromechanics of High Strain-Rate Deformation and Failure of Dual- Phase Composites |
27 JUN 1997 |
7 pages |
| Authors:
G. Bao; JOHNS HOPKINS UNIV BALTIMORE MD
|
| Under the support of ARO (Grant number: DAAH04-94-G-0086, Solid Mechanics Program, Program Director, Dr. K. Iyer), a three-year basic research program is carried out on the micromechanics of high strain-rate deformation and failure in dual-phase composites. Three composite material systems are studied: (1) tungsten heavy alloys and tungsten-based composites; (2) ceramic particle reinforced metal matrix composites; and (3) penetrator/armor material combinations. Emphasis is placed on the relationship between the microstructure ... |
|
| Characterization of the Dynamic Response of Thick Composite Structures |
JUN 97 |
6 pages |
| Authors:
MAINE UNIV AT ORONO
|
| The objective for this research remains at contributing to the understanding of the fundamental mechanisms which determine the response of thick composite structures to time dependent loading. The following specific objectives were originally proposed and, with some modification, continue to form the basis for the research plan: (1) Postulate the primary micromechanical attributes in the range of relatively small strain which are expected to directly affect frequencies, mode shapes, participation ... |
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| Micromachined Shear Sensors for Fluid Flows |
15 MAY 97 |
102 pages |
| Authors:
Kenneth S. Breuer; Martin A. Schmidt; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF ELECTRICAL ENGINEERING AND COMPU TER SCIENCE
|
| The three year program focused on modeling of fluid mechanics in micromachined systems. The program supported a graduate student at MIT (Ed Piekos). The program was successful in exploring the effects of rarefaction and the use of different computational tools for analyzing and simulating flows in MEMS devices. |
|
| Micro-Opto-Mechanical Systems |
08 APR 97 |
40 pages |
| Authors:
Kaigham J. Gabriel; CASE WESTERN RESERVE UNIV CLEVELAND OH
|
| We have finished a three year university/industry cooperative program for basic research and technology development in the area of microoptomechanical systems (MOMS). The impetus of this work came from the results of our research on microactuators as well as a review of other current research. Our program addressed two components: (1) the development of basic microoptomechanical devices which can be combined in to complex MOMS; and (2) the development of ... |
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| Micromechanism Based Modeling of Structural Life in Metal Matrix Composites |
23 MAR 1997 |
34 pages |
| Authors:
David H. Allen; Dimitris C. Lagoudas; TEXAS A AND M UNIV COLLEGE STATION CENTER FOR MECHANICS OF COMPOSITES
|
| This report details the most recent accomplishments that have lead towards the fulfillment of the grant objectives. These achievements include: (1) life prediction of continuous fiber metal matrix composites; (2) the influence of heat treatment on the mechanical properties and damage development in a SiC/ Ti-15-3 MMC; (3) the experimental characterization of oxidation on fracture surfaces and crack growth behavior; (4) modeling the effects of oxidation on the crack growth ... |
|
| Experimental Micromechanics of Geomaterials Through Computer Visualization |
30 OCT 96 |
4 pages |
| Authors:
Roman D. Hryciw; MICHIGAN UNIV ANN ARBOR DEPT OF CIVIL ENGINEERING
|
| The objective of the research program was development of computer vision techniques for experimental soil micromechanic and for characterization of soils, both in the laboratory and in-situ. for micromechanics research, a particle tracking system consisting of state-of-the-art hardware and developed software tools, was assembled for monitoring the kinematics of particulate assemblies undergoing large strain deformations and flow. The utility if this system, the testing methodologies and the suite of developed ... |
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| A Micromechanical Investigation of Instability in Particulate Media |
SEP 96 |
7 pages |
| Authors:
J. P. Bardet; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF CIVIL ENGINEERING
|
| The main research objective is to investigate the microscopic origins of shear band instability in particulate media. Our methodology combines computational micromechanics, laboratory experiments, and continuum mechanics. The particular research objective are (1) to improve the existing methods of computational micromechanics, (2) to examine the formation of shear bands, (3) to investigate the effects of grain rotation on shear strength and shear bands, (4) to study liquefaction instability, and (5) ... |
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| Modeling of Crack Initiation and Growth in Solid Rocket Propellants Using Macromechanics and Micromechanics Theories |
SEP 96 |
96 pages |
| Authors:
James H. Lee; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Modeling and simulation of crack initiation and propagation in solid rocket propellant materials were conducted using both the macromechanics approach and the micro/macromechanics approach. Due to their composition, the solid rocket propellant can be construed as particle reinforced composites. The macromechanics approach entailed a numerical simulation of a finite element model to predict the crack behavior based on the damage initiation, growth, and local saturation. Its results were then compared ... |
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| Micromechanics and Constitutive Modeling og Granular Materials in Stress Reversal and Cyclic Loading Locaized Deformation: Experimental Observation and Modeling |
20 DEC 95 |
47 pages |
| Authors:
Sia Nemat-Nasser; CALIFORNIA UNIV SAN DIEGO LA JOLLA CENTER OF EXCELLENCE FOR ADVANCED MATERIAL S
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| The work performed under this grant, focused on the process of initiation and growth of shear bands in frictional granules. Such localized deformations commonly occur in particulate media and are of considerable engineering and scientific importance. They occur in a variety of areas of advanced materials processing, at different scales. They are a common mode of failure in soil masses and geological formations. A technique has been developed to study ... |
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Reports by Keyword(s)
*MICROMECHANICS
