| Static and Fatigue Damage in High Temperature Composites |
14 SEP 95 |
95 pages |
| Authors:
G. J. Dvorak; Y. A. Bahei-el-Din; RENSSELAER POLYTECHNIC INST TROY NY
|
 | This final report presents the experimental and theoretical work performed in our research program on static and fatigue damage in high temperature composites. The theoretical part focused on development and implementation of a new Transformation Field Analysis (TFA) for inelastic laminates, which employs unit-call, periodic array models, as well as averaging micromechanical models together with any constitutive law for thermo- viscoplastic and other inelastic deformation. Moreover, we have initiated modeling ... |
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| Nonlinear Control of Missiles |
SEP 95 |
189 pages |
| Authors:
Kevin A. Wise; Jack L. Sedwick; Rowena L. Eberhardt; MCDONNELL DOUGLAS CORP ST LOUIS MO
|
| The problem of designing flight control system for high performance anti-air missiles is discussed in this report. The research addresses three areas of missile autopilot design. The first area investigates the application of nonlinear H-infinity optimal control for an integrated aerodynamic/thrust vector controlled missile. The second area investigates the design of autopilots for missiles using on-off reaction control valve actuators. A sliding mode control law is developed using H-infinity design ... |
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| The Use of Analog Track Angle Error Display for Improving Simulated GPS Approach Performance |
AUG 95 |
49 pages |
| Authors:
C. M. Oman; M. S. Huntley Jr.; S. A. Rasmussen; S. K. Robinson; JOHN A VOLPE NATIONAL TRANSPORTATION SYSTEMS CENTER CAMBRIDGE MA
|
| The effect of adding track angle error (TAE) information to general aviation aircraft cockpit displays used for GPS nonprecision instrument approaches was studied experimentally. Six pilots flew 120 approaches in a Frasca 242 light twin aircraft simulator using crosswind and turbulence. Twenty- five-mile-long approach geometries were used, with and without 45 degree dogleg turns on final approach. Performance and workload using three TAE display formats were compared against results with ... |
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| Eaton Throat-Valve Element Modifications Preliminary Report |
JUL 95 |
244 pages |
| Authors:
Marcela R. Stacey; James G. Arendts; Ray A. Berry; Gary E. Korth; Paul R. Schwieder; IDAHO NATIONAL ENGINEERING LAB IDAHO FALLS
|
| This report documents the development and findings of a computer model that simulates the behavior of the Eaton-Throat Valve Element (ETVE) prototype, and describes a proposed modification concept for the ETVE. This high speed valve was designed for the U.S. Army Research Laboratory, Aberdeen Proving Ground, MD, to control the simulation of the dynamic effects of a nuclear blast. The computer model reveals three main findings: (1) the ETVE chatters ... |
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| Split Gasket Attachment Strip. |
30 MAY 1995 |
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| Authors:
Paul E. Moody; DEPARTMENT OF THE NAVY WASHINGTON DC
|
 | The present invention relates to a method and hardware for bonding together ends of a sealing strip. The method of the present invention comprises the steps of cutting a slot in both a first end and a second end of a sealing strip, inserting an attachment strip having a plurality of engaging members into the slot cut into the first end, applying adhesive to the second end of the sealing ... |
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| CTWALL - A Microcomputer Program for the Analysis of Retaining and Flood Walls . Computer-Aided Structural Engineering (CASE) Project. (User's Guide) |
DEC 94 |
156 pages |
| Authors:
Michael E. Pace; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS INFORMATION TECHNOLOG Y LAB
|
| CTWALL is a computer program that assesses the stability of T-type retaining and flood walls. The purpose of the program is to assess these structures in accordance with EM 1110-2-2502 and ETL 1110.2-322. CTWALL will evaluate the overturning and sliding stability of a retaining or flood wall in accordance with the aforementioned criteria documents. This instruction report is organized to present CTWALL by describing the installation and equipment requirements, giving ... |
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| Rock Foundations |
30 NOV 1994 |
232 pages |
| Authors:
CORPS OF ENGINEERS WASHINGTON DC
|
| This manual provides technical criteria and guidance for design of rock foundations for civil works or similar large military structures. This manual applies to HQUSACE elements, major subordinate commands, districts, laboratories, and field operating activities. The manual provides a minimum standard to be used for planning a satisfactory rock foundation design for the usual situation. Chapter 2 provides a discussion on design considerations and factor of safety. Chapter 3 provides ... |
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| Advanced Solid Lubricant Films by Ion-Beam Assisted Deposition |
28 NOV 94 |
12 pages |
| Authors:
Irwin L. Singer; Robert N. Bolster; Larry E. Seitzman; Kathryn J. Wahl; Marshall B. Peterson; NAVAL RESEARCH LAB WASHINGTON DC
|
| NRL is developing advanced solid lubricating films for bearing assemblies. The films are deposited by ion-beam assisted deposition (IBAD) to thickness that can be controlled from 0.02 micrometers (1 micron inch) to greater than or equal to 1 micrometer (40 microns inch). Unlike evaporated or sputter-deposited films, IBAD films are dense and adhere well to virtually all solid surfaces. Durable films have been deposited on bearing steels, Ti alloys and ... |
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| Ramp Junction. |
01 NOV 1994 |
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| Authors:
Patrick R. Kane; Billie R. Karrh; Kit Mack; Samuel J. Oppedisano; DEPARTMENT OF THE NAVY WASHINGTON DC
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| An apparatus for spanning the distance between a fixed first platform and a movable second platform includes a ramp; a first pivoting junction located between one end of the ramp and the fixed first platform, and a second sliding junction located between the other end of the ramp and the movable second platform. The first pivoting junction accommodates pitch, roll and heave motion between the fixed platform and the ramp ... |
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| Friction and Energy Dissipation at the Atomic Scale: A Review |
OCT 1994 |
13 pages |
| Authors:
I. L. Singer; NAVAL RESEARCH LAB WASHINGTON DC SURFACE CHEMISTRY BRANCH
|
| Discussions of energy dissipation during friction processes have captured the attention of engineers and scientists for over 300 years. Why then do we know so little about either dissipation or friction processes? A simple answer is that we cannot see what is taking place at the interface during sliding. Recently, however, devices such as the atomic force microscope have been used to perform friction measurements, characterize contact conditions, and even ... |
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| Video Transmission for Quantized Variable Bandwidth Networks |
08 SEP 94 |
19 pages |
| Authors:
Christopher C. Yu; NAVAL RESEARCH LAB WASHINGTON DC
|
| Transmission of variable bit-rate sources, such as video, over channels with quantized rates is discussed. An optimal scheme for transmission, based on the Viterbi algorithm, is described. A sliding window sub-optimal algorithm is introduced which significantly reduces algorithmic complexity while maintaining near-optimum performance. Simulation of the performances of the optimal and sub-optimal algorithms, as well as comparisons to a constant bit rate channel is completed. Video compression, Asynchronous transfer mode ... |
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| Superplastic Ceramics |
01 SEP 94 |
10 pages |
| Authors:
Oleg D. Sherby; Woo-Jin Kim; STANFORD UNIV CA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Superplasticity is a newly observed phenomenon in ceramics, with the first publication appearing in 1986. The current program has centered on an experimental study of superplasticity in polycrystalline iron carbide. This material has been made superplastic by utilization of two processing methods: powder processing and ingot-processing. In both cases the end microstructure is a continuous phase of ultra-fine grained iron carbide. The ultra-fine grained powder processed material was successfully gas-pressure ... |
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| Superstrength Metal Composite Material and Process for Making the Same. |
02 AUG 1994 |
|
| Authors:
Norman P. Louat; Virgil Provenzano; M. A. Imam; Kuntimaddi Sadananda; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A metal composite material provides improved strength at all temperatures, in particular at those temperatures greater half the melting point of its matrix. The metal composite material is at least 50 volume percent hard particulate material in a matrix which is significantly more ductile than the hard particulate material. At or above 50 volume percent hard particulate material, each particle is surrounded by a thin film of the matrix material. ... |
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| Twin Disc Gear Tooth Simulator |
MAY 94 |
125 pages |
| Authors:
Martin W. Eusepi; James F. Dill; MECHANICAL TECHNOLOGY INC LATHAM NY
|
| This report describes the results of an effort to develop a disc on disc test rig for evaluating lubricant load capacity. The goal of the program has been to develop a reliable disc on disc (or Twin Disc) test rig capable of providing more reliable and lower cost evaluation of lubricant load capacity than the Ryder gear test which is currently used. Disc rigs have been evaluated for this application ... |
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| Lubricant Evaluation and Performance II |
FEB 94 |
475 pages |
| Authors:
Costandy S. Saba; Michael A. Keller; Kenneth K. Chao; Douglas K. Toth; Mary F. Borchers; DAYTON UNIV OH RESEARCH INST
|
| Thermal and oxidative stability, deposition and foaming techniques were developed for predicting the performance of candidate 4 cSt lubricants, polyphenyl ether (PPE), C-ether and other experimental fluids for use in advanced aircraft turbine engines. A novel sealed tube test was developed to study the rate of reaction in both liquid and vapor phase using only microliter quantities of the lubricants. Blending agents and/or diluents were used to improve the low ... |
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| Remote Control of Transcranial Doppler (TCD) Probe During Centrifuge Exposures up to 9 +Gz |
JAN 94 |
6 pages |
| Authors:
Ulf I. Baldwin; Paul Werchan; Travis Eddy; SOUTHEASTERN CENTER FOR ELECTRICAL ENGINEERING EDUCATION INC ST CLOUD FL
|
| TCD systems have been successfully used in clinical practice for estimating cerebral perfusion by registering blood flow velocity in the middle cerebral artery. However, when used in centrifuges, probe movement during high +Gz have resulted in the loss of Doppler signal making interpretations of data very difficult. To solve this problem, the Doppler probe and three electrical motors were mounted on a tightly fitted helmet. Remote control of these motors ... |
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| Mechanics of Failure of High Temperature Metal Matrix Composites |
22 DEC 93 |
248 pages |
| Authors:
Demitris A. Kouris; ARIZONA STATE UNIV TEMPE DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| Results of a three-year research effort aimed at developing an understanding of the factors controlling transverse strength and failure of intermetallic composites are presented. Experiments were conducted involving several aluminide matrix composites; two types of fibers were used in order to allow for large as well as small residual stresses. On the basis of the in situ observations and with the aid of high resolution strain mapping, the relevant damage ... |
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| Wear Reduction in Ceramic Bearings by Surface Generated Pyrolytic Carbon Continuously Replenished by Ethylene Gas |
13 DEC 93 |
46 pages |
| Authors:
J. L. Lauer; L. C. Davis; RENSSELAER POLYTECHNIC INST TROY NY
|
| Sliding tests with a pin-on-disc tribometer and both sliding and rolling tests with a modified four-ball tester at bulk temperatures of about 500 deg C and contact pressures of about 2.2 GPa have demonstrated up to 80% reductions of friction and wear with silicon nitride surfaces when a stream of ethylene is directed into the conjunction region. The effects are even more pronounced when the ethylene is prenucleated by a ... |
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| New Micro- and Macroscopic Models of Contact and Friction |
29 NOV 93 |
185 pages |
| Authors:
W. W. Tworzydlo; W. Cecot; J. T. Oden; C. H. Yew; COMPUTATIONAL MECHANICS CO INC AUSTIN TX
|
| This is the final report for the three year research project dedicated to the development of new asperity-based models of frictional interfaces. The main concept is to combine statistical homogenization methods with a realistic nonlinear finite element analysis of surface micro-asperities, and thus produce new asperity-based models of contact and friction. Research in the project started with the development of a complete theory and software for the statistical homogenization of ... |
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| The Nanometer-Scale Mechanics of Gold Films |
23 NOV 93 |
30 pages |
| Authors:
P. Tangyunyong; R. C. Thomas; J. E. Houston; T. A. Michalske; R. M. Crooks; NEW MEXICO UNIV ALBUQUERQUE DEPT OF CHEMISTRY
|
| We have used interfacial force microscopy (IFM) to monitor the mechanical deformation of single nanometer-sized grains in Au thin films. Our results show that protruding grains, which represent early-stage delamination, display multiple deformation mechanisms including grain-boundary sliding and intragranular plasticity. The unprecedented load displacement control capability of the IFM provides data that is used for the first time to quantitatively distinguish and evaluate individual deformation processes. |
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| Tribological Studies of Silicon for Magnetic Recording Applications (Invited) |
05 OCT 93 |
24 pages |
| Authors:
Bharat Bhushan; Vilas N. Koinkar; OHIO STATE UNIV COLUMBUS COMPUTER MICROTRIBOLOGY AND CONTAMINATION LAB
|
| Read-write sliders made of silicon using integrated-circuit technology offer advantages of low-cost and high volume production. In the present study our objective is to investigate whether the friction and wear performance of bare silicon is adequate for disk drive application or whether certain coatings/treatments are necessary for low friction and wear. Macrotribological experiments have been performed with various pin/slider materials and magnetic disks in a modified disk drive. Microtribological studies ... |
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| Interface Phenomena in Metal-Ceramic Composites |
27 SEP 93 |
52 pages |
| Authors:
Rishi Raj; CORNELL UNIV ITHACA NY DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This report describes theoretical and experimental results that link the properties of the heterointerface to the macroscopic mechanical behavior of metallic composites where the continuous phase is a metal and the hard phase is a ceramic (MMCs) or an intermetallic (IMCs). The results emphasize that the properties of the composites depend on the interaction between cohesive strength of the M/C or M/I interface and the physical microstructural scale of the ... |
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| Numerical and Analytical Solutions to Benchmark Problems Related to Tunnel Mechanics |
01 SEP 93 |
122 pages |
| Authors:
Donald A. Simons; LOGICON R AND D ASSOCIATES LOS ANGELES CA
|
| In this report, five numerical approaches to problems of tunnel dynamics are compared with each other and--wherever possible--with exact analytic solutions. The medium is an idealization of a jointed rock mass. The intact rock is linear elastic-plastic with a pressure-dependent failure surface and associated plastic flow law. There are two orthogonal sets of equally spaced joints. Each joint is nonlinear elastic in the normal direction and linear elastic with Coulomb ... |
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| Mine Avoidance and Localization for Underwater Vehicles Using Continuous Curvature Path Generation and Non-Linear Tracking Control |
SEP 93 |
74 pages |
| Authors:
Dean J. Cottle; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL ENGINEERING
|
| Many underwater vehicles have been designed to follow a straight path using linear approximations about that path. Tracking a dynamic path of arbitrary but continuous curvature may often be desired. This will require a nonlinear controller with enhanced robustness properties. One point of this thesis is to show how nonlinear control using sliding modes may be applied to follow a dynamic path. In a mine warfare setting using Autonomous Underwater ... |
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| Microscopic Modeling of Tribological and Interfacial Phenomena |
31 JUL 93 |
|
| Authors:
Uzi Landman; GEORGIA INST OF TECH ATLANTA SCHOOL OF PHYSICS
|
| Atomic-scale energetics, structure and dynamical mechanisms underlying interfacial processes, in particular for systems when two materials are brought together, separated or slide against each other, are of fundamental importance for basic science and technology in areas such as interfaces, confined fluids, adhesion, tribology, junctions, lubrication, wear, surface modifications, and nano technology. Our research is focused on the development and implementation of methods of atomistic molecular dynamics simulations and applications to ... |
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| Lock Operator for Inactive Magazine Door Locking Bolt System. |
27 JUL 1993 |
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| Authors:
Craig Horton; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A lock operator located between a backing plate and sliding cover includes a pivot plate for activating and deactivating the main boltworks and a relocker, an overtravel stop assembly for sequestering the pivot plate to prevent relock, a spring braised knob for locking the pivot plate in the locked or unlocked position, a pin for locking the sliding cover, pivot plate and locking plate in the locked position and means ... |
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| Solid Lubricants for Space Structures. Phase 2 |
14 JUN 93 |
97 pages |
| Authors:
T. S. Sudarshan; MATERIALS MODIFICATION INC FAIRFAX VA
|
| In this Phase 11 effort, copper-lead alloys of three different compositions (90-10, 75/25, and 50/50 copper-lead) were processed by swirl die continuous casting in the form of ingots and further processed into powders using the gas atomization method. The powders were compacted using shock campaction and hot isostatic pressing. Friction and wear studies revealed that the 75/25 alloys had the best friction and wear rates under a range of sliding ... |
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| Properties of Interfacial Tribo-Films |
JUN 93 |
239 pages |
| Authors:
D. D. Makel; D. Kuhlmann-Wilsdorf; VIRGINIA UNIV CHARLOTTESVILLE SCHOOL OF ENGINEERING AND APPLIED SCIENCE
|
| Research has been conducted on the properties of interfacial films of the kind formed in the course of sliding wear, named 'tribo-films.' Using specialized instrumentation, in particular the so-called Hoop Apparatus and a Bridgman-Anvil Device, we have found many new insights into the fundamental mechanisms responsible for the phenomena observed during sliding. In particular, advances have been made in, (1) the understanding of lubrication through adsorbed films, (2) the fundamental ... |
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| Integrated Fundamental Research on Current Collection |
JUN 93 |
53 pages |
| Authors:
Doris Kuhlmann-Wilsdorf; Leo Tran; VIRGINIA UNIV CHARLOTTESVILLE SCHOOL OF ENGINEERING AND APPLIED SCIENCE
|
| The aim of our research was to add to the basic understanding in the area of current collection with particular emphasis on topics likely to benefit practical objectives. Under sponsorship of this contract, 23 papers were published in the international literature. Additionally, 13 invited lectures and 11 contributed lectures on various aspects of this research were delivered at universities, research laboratories, and international conferences by the principal investigator and coworkers. ... |
|
| Inexpensive Capillary Discharge X-Ray Laser Driver |
28 MAY 93 |
35 pages |
| Authors:
Alexander M. Panin; MOXTEK INC OREM UT
|
| In Phase I of the research we computationally modelled a capillary discharge device capable of producing the necessary plasma conditions to demonstrate ASE in argon at a wavelength of about 700 angstroms. Phase 11 of the research will involve the development and diagnosis of the experimental apparatus necessary to demonstrate ASE in argon. The scaling and modification of that apparatus to demonstrate ASE at shorter wavelengths using higher-Z materials will ... |
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| Diagnostics and Methods for Real-Time Laser Microchemistry |
31 MAR 93 |
7 pages |
| Authors:
Daniel Ehrlich; EHRLICH ASSOCIATES LEXINGTON MA
|
| Among the of the main goals of the program have been the development of digital real-time microchemical processes and diagnostics. Further objectives have been the design of a stable platform, and the mechanical subsystems and electronic circuits to provide real-time machine control. These will be the basis for the study of control and stabilization methods. Specific subassemblies designed were the massive 1.5- inch-thick steel plate, the mechanical frame support, the ... |
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| The Processing and Mechanical Properties of High Temperature/High Performance Composites. Book 1. Constituent Properties of Composites |
28 FEB 93 |
336 pages |
| Authors:
Anthony G. Evans; Frederick A. Leckie; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
|
| Partial Contents: A Microcomposite Test Procedure for Evaluating the Constituent Properties of Ceramic Matrix Composites; Design, Analysis and Application of an Improved Push-Through Test for the Measurement of Interface Properties in Composites; Fiber Bundle Push-Out: A Technique for the Measurement of Interfacial Sliding Properties; Mechanics of the Fiber Pushout Test; Effects of Fiber Roughness on Interface Sliding in Composites; Fiber Coating Concepts for Brittle Matrix Composites; Preliminary Assessment of Mica ... |
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| Macro- and Micro-Mechanics of Mixed-Mode Dynamic Fracture of Concrete. Part 1. Micro-Mechanic Analysis |
14 FEB 93 |
92 pages |
| Authors:
Chang-Te Yu; Zhikai Guo; A. S. Kobayashi; Neil M. Hawkins; UNIV OF WASHINGTON SEATTLE DEPT OF MECHANICAL ENGINEERING
|
| A hybrid experimental-numerical procedure was used to analyze the micro-mechanics of the mixed-mode, static and dynamic fracture of a concrete three-point bend specimen with an offset precrack. Four/two beam moire interferometry was usedto record simultaneously separating horizontal and vertical displacements associated with stable/rapid growth. An elasto-static/ elasto-dynamic finite element code was execute in its propagation mode with assumed crack closure stress (CCS) versus crack opening displacement (COD) and crack shearing ... |
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| Newtonian Viscous Flow and Superplasticity in Fine Grained Metallic Alloys |
31 JAN 93 |
15 pages |
| Authors:
Oleg D. Sherby; Eric Taleff; Shih-Chung Cheng; STANFORD UNIV CA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Superplasticity in crystalline solids is an area of expanding scientific and technical interest Superplastic materials are characterized by a high value of the strain-rate-sensitivity exponent, m. kinds of superplasticity have been identified: fine structure superplasticity (FSS) and internal stress superplasticity (ISS). In the case of FSS materials, a strain-rate-sensitivity exponent equal to about 0.5 is usually found and these materials deform principally by a grain-boundary-sliding (g.b.s.) mechanisms accommodated by slip, ... |
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| Simulation-Based Performance Analysis of Several Types of Normalizers Under Correlated Stationary Noise Conditions |
21 JAN 93 |
|
| Authors:
Fyzodeen Khan; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV NEW LONDON CT NEW LONDON DETACHMENT
|
| The results of a simulation-based performance analysis of several types of normalization algorithms commonly considered for use in active sonar applications are presented. The techniques investigated are the mean value (MV), two pass peak shear (2PP), greater-of (GO) mean values and the ordered statistic (OS). Each algorithm incorporates a sliding, split window which encompasses the data to be used to compute the normalizing parameter and is centered on the data ... |
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| Discrete Sliding Mode Control for Nonlinear Sampled Data Systems |
93 |
|
| Authors:
Jean M. Fernand; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| Nonlinear control theory has been successfully applied to continuous, nonlinear, autonomous plant models. Implementation of these continuous control laws, using digital computers, has relied upon high sample frequencies to approximate the performance of continuous control. This thesis extends the design of continuous sliding mode control to discrete and to sampled data systems. Continuous, nonlinear, autonomous, second order dynamic plant models are discretized using an approximation to a Taylor series expansion. ... |
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| Integrated Fundamental Research On Current Collection |
OCT 92 |
|
| Authors:
Doris Kuhlmann-Wilsdorf; VIRGINIA UNIV CHARLOTTESVILLE DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| The aim of our research has been to add to basic understanding in the area of current collection with particular emphasis on topics likely to benefit practical objectives. Under sponsorship off this contract twenty three papers were published in the international literature as listed in the last section. Additionally, thirteen invited lectures and eleven contributed lectures on various aspects of this research were delivered at Universities, Research Laboratories and International ... |
|
| Tactile Sensing and Control in Humans and Robotic/Teleoperated Systems |
04 AUG 92 |
7 pages |
| Authors:
Mark R. Cutkosky; Robert Howe; Roland Johansson; Goran Westling; Benoni Edin; STANFORD UNIV CA DEPT OF MECHANICAL ENGINEERING
|
| The most significant result of the Stanford/Harvard/Umea collaboration is a promising new approach to grasp force control in manipulation with robots and teleoperators. Experiments at Umea showed that human subjects control grasp forces and apply manipulation strategies using information from fast-acting (FAI and FAII) tactile afferents which signal events such as the onset of slipping between the fingers and a grasped object. An information exchange between Umea and Stanford led ... |
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| The Deformation Characteristics and Microstructural Dynamics of an AL- 10MG-0.1ZR Alloy |
JUN 92 |
|
| Authors:
James F. Buckley II; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| An investigation into microstructural evolution during processing and superplastic deformation of an Al-10Mg-0.1Zr alloy was conducted. Processing schedules were modified to enhance particle-stimulated nucleation of recrystallization and refine subsequent gain size. Strain rates varying over three orders of magnitude were utilized in subsequent testing of processed material. At lower strain rates of about 10-4 sec-1 coarsening of the microstructure was apparent and elongations of 277% were obtained. A strain rate ... |
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| Tests for Determining Failure Criteria of Ceramics under Ballistic Impact |
JUN 92 |
137 pages |
| Authors:
Richard W. Klopp; Donald A. Shockey; SRI INTERNATIONAL MENLO PARK CA
|
| A three-year Balanced Technology Initiative (BTI) program to develop tests for determining the failure criteria of ceramics under ballistic impact is described. The phenomenology of the penetration of a confined ceramic block by a long rod penetrator was established by examining the fracture damage in targets after ballistic testing. The material properties that govern the penetration resistance of ceramics were deduced. Two plate impact tests-the high-strain-rate pressure/shear test and the ... |
|
| Micromechanics of Interfaces in High Temperature Composites |
30 MAY 92 |
131 pages |
| Authors:
Toshio Mura; Katherine T. Faber; NORTHWESTERN UNIV EVANSTON IL CENTER FOR QUALITY ENGINEERING AND FAILURE PREV ENTION
|
| Both theoretical and experimental approaches have been used to examine the micromechanics of interfaces in ceramic-matrix, fiber-reinforced composites. In order to examine variables which allow for the optimization of fracture, toughness, analytical solutions first were developed to describe the stress displacement fields for a cylindrical inclusion adjoining a surface of an elastic half-space (equivalent to a single fiber intercepting a matrix crack). This same equivalent inclusion model was used to ... |
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| The Synthesis and Characterization of Tribophysical Layers on Diamond and Silicon Carbide Surfaces |
MAY 92 |
44 pages |
| Authors:
John T. Yates Jr; PITTSBURGH UNIV PA DEPT OF CHEMISTRY
|
| A new ultrahigh vacuum apparatus, dedicated to the study of the surface chemistry of diamond single crystals, has been completed and the first scientific experiments have been done. This apparatus incorporates XPS, LEED, ESDIAD, HREELS, and TPD facilities for the study of the fluorination and hydrogenation of diamond single crystals. The apparatus is being employed for studies of atomic hydrogen/deuterium adsorption on diamond(100) in initial experiments prior to the use ... |
|
| Comparison of Synchronization Techniques for the AFIT Direct Sequence Spread Spectrum System |
21 APR 92 |
82 pages |
| Authors:
Edward A. Bednar; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
|
| The purpose of this study is to analyze and evaluate the performance of several code synchronization methods that could be used in the Air Force Institute of Technology's (AFIT) Direct-Sequence Spread Spectrum (DSSS) communication system. These methods include the sliding correlator, transmitted reference, sequential estimation, and three types of matched filters. The matched filters are the baseband matched filter, delay line matched filter, and the convolver. The criteria used for ... |
|
| A Review of the Processes that Control Snow Friction |
APR 92 |
47 pages |
| Authors:
Samuel C. Colbeck; COLD REGIONS RESEARCH AND ENGINEERING LAB HANOVER NH
|
| There is a long history of interest in snow friction, but it is still necessary to speculate about the details of the processes. Roughness elements and contact areas must be characterized before the basic processes can be well understood. These parameters change with movement over snow and, in fresh snow, probably change along the length of the slider. Friction results from a mixture of processes: dry, lubricated, and possibly capillary. ... |
|
| SHIPMO5: An Updated User's Manual Incorporating New Wave Spectra and Ship-Referenced Forces |
APR 92 |
|
| Authors:
Kevin A. McTaggart; Ross Graham; DEFENCE RESEARCH ESTABLISHMENT ATLANTIC DARTMOUTH (NOVA SCOTIA)
|
| The ship motion computer program SHIPMO has been revised to increase its capabilities in several different areas. The new version of the program can compute forces relative to local ship axes and the resulting incidence of motion-induced interruptions or sliding events. Seakeeping positions may now be offset from the ship center-line. The program now includes expanded wave spectra capabilities, including multi-directional spectra. Motion computations may include hydrodynamic end effect terms, ... |
|
| On-Line Identification of the Speed, Steering and Diving Response Parameters of an Autonomous Underwater Vehicle from Experimental Data |
MAR 92 |
179 pages |
| Authors:
Fredric G. Bahrke; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The experimental response data from autonomous maneuvering using the NPS AUV II vehicle has been analyzed with a view to defining Kalman filters to provide on-line estimates of system parameters and their variability. Kalman filters, designed for parameter estimation are expected to be the first step in the development of autonomous fault detection systems for underwater vehicles. Secondly, extraction of vehicle hydrodynamic coefficients from these parameters can help to develop ... |
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| Constitutive Modelling for Granular Material under Finite Strains with Particle Slidings and Fabric Changes |
04 FEB 92 |
|
| Authors:
Ching S. Chang; MASSACHUSETTS UNIV AMHERST DEPT OF CIVIL ENGINEERING
|
| The overall objective of this research is to develop a constitutive model for granular material under finite strains with explicit consideration of particle sliding and the consequent fabric change. The specific objective of this research is focused on the development of a stress strain theory that accounts for the microstructure and the non-uniform strain field of the particle assembly. The developed theoretical model is evaluated by results obtained from computer ... |
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| Modelling of Heavily Loaded Lubricated Contacts |
FEB 92 |
|
| Authors:
Farshid Sadeghi; William D. McClug Jr.; Kyung-Hoon Kim; Kevin Osborn; Brian Lance; PURDUE RESEARCH FOUNDATION LAFAYETTE IN
|
| Thermal elastohydrodynamic (EHD) lubrication of rolling/sliding line contacts is investigated to develop an interactive computer program for prediction of lubrication system performance. The user inputs lubricant and mechanical system physical properties as well as operating conditions of load and speed for calculation of contact zone pressure, temperature, traction, and stresses. This program is one of the first to include thermal effects in calculations and, therefore, can more accurately assess the ... |
|
| Superstrength Metal Composite Material and Process for Making the Same. |
31 JAN 1992 |
|
| Authors:
N. P. Louat; V. Provenzano; M. A. Imam; K. Sadananda; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A metal composite material provides improved strength at all temperatures, in particular at those temperatures greater half the melting point of its matrix. The metal composite material is at least 50 volume percent hard particulate material in a matrix which is significantly more ductile than the hard particulate material. At or above 50 volume percent hard particulate material, each particle is surrounded by a thin film of the matrix material. ... |
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| Performance of Selected Fabrics on the Decontaminable Litter and Litter Mattress to Correct a Problem of Unexpected Sliding during Patient Loading on a C-9 (Nightingale) Aircraft |
30 JAN 92 |
35 pages |
| Authors:
William H. Reams; David L. Danley; ARMY BIOMEDICAL RESEARCH AND DEVELOPMENT LAB FORT DETRICK MD
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| During evaluation of the decontaminable litter, Air Force personnel noted that a patient laying on a vinyl litter mattress slid unexpectedly while being carried up a 19 degree loading ramp of the C-9 (Nightingale) aircraft. To address this problem, a number of selected materials were fabricated into litter and mattress covers. The slipperiness of each product was measured by placing a subject on the test litter with or without a ... |
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Reports by Keyword(s)
SLIDING
