| Numerical Study of Effects of Fluid-Structure Interaction on Dynamic Responses of Composite Plates |
Sep-2009 |
115 pages |
| Authors:
Peter K Kendall; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
 | Composite materials are seeing increased use in structural applications because of their various benefits. When composite structures are employed in a water environment, their dynamic responses are greatly affected by the fluid medium. Water density is comparable to many composite materials and the effects of fluid-structure interaction on dynamic behaviors of composite structures are significant. The effects of fluid-structure interaction include changes of frequency, magnitude, energy dissipation, etc., of structural ... |
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| Effect of Temperature and Viscoelastic Creep on the Clamp-Up Load in Hybrid Composite/Metal Bolted Joints |
17-Aug-2009 |
152 pages |
| Authors:
Vincent Caccese; Senthil S Vel; Mauricio Fernandex; MAINE UNIV AT ORONO DEPT OF MECHANICAL ENGINEERING
|
| Hybrid composite to metal bolted joints are the focus of much research due the inherent advantages that they present. In particular, they are very attractive to designers and engineers alike due to their simplicity and ease of disassembly. However, hybrid connections are particularly susceptible to metal fatigue, stress relaxation primarily due to viscoelastic creep of the composite, thermal effects due to coefficient of thermal expansion mismatch, galvanic corrosion between the ... |
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| Limiting Impact Force Due to Yielding and Buckling of the Plates and Internal Structural Frame at the Bow of a Barge during Its Head-on Impact with a Bullnose or Cellular Structure |
Aug-2009 |
51 pages |
| Authors:
Robert M Ebeling; Terry W Warren; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS INFORMATION TECHNOLOGY LAB
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| This report presents a research study conducted to predict the impact forces that occur when a barge train impacts head-on with a circular concrete or concrete-filled structure. These structures are found at the end of lock approach walls as semicircles called bullnoses, as circular cells, and as mooring cells. This research was conducted using finite element analysis. A detailed finite element model of the bow of a jumbo hopper barge ... |
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| The Distribution of Breaking and Non-Breaking Wave Impact Forces |
Mar-2009 |
40 pages |
| Authors:
Anne M Fullerton; Ann Marie Powers; Don C Walker; Susan Brewton; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD HYDROMECHANICS DIRECTORATE
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| The magnitude of wave impact loads varies greatly, depending upon whether the wave is breaking, as well as on the wave height, length, steepness, and the geometry and immersion of the impacted structure. This report describes an experiment that was performed to characterize the distribution of breaking and non-breaking wave impact loads over a surface, similar to those performed in 2005 with non-breaking wave impact loads and those performed in ... |
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| Development of a Ballistic Specification for Magnesium Alloy AZ31B |
Dec-2008 |
52 pages |
| Authors:
Tyrone L Jones; Richard D DeLorme; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The U.S. Army Research Laboratory (ARL) and Magnesium Elektron North America (MENA) have conducted a joint effort to develop and evaluate rolled plate in commercially available magnesium alloy-temper AZ31B-H24. MENA produced the rolled product and conducted the mechanical analysis, while ARL performed the ballistic analysis. The magnesium alloy plates were parametrically compared with the minimum performance requirements of aluminum alloy 5083-H131 temper rolled plate using various armor-piercing and fragment-simulating projectiles ... |
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| Synthetic Seismogram Study of the Eastern Central Andes |
30-Sep-2008 |
9 pages |
| Authors:
Estela Minaya; Evanz Lazaro; Percy Aliaga; Magaly Gonzalez; Wilfredo Cano; OBSERVATORIO SAN CALIXTO LA PAZ (BOLIVIA)
|
| Along the South American coast, there have been several earthquakes of great magnitude--between 7.5 and 9.5 Mw, with ruptures 50 km to 950 km long, producing maximum intensities between VII and X (MM)-particularly in two seismic gaps located in southern Peru and northern Chile. In these places, two large earthquakes occurred in the 19th century, in 1868 and in 1877, establishing the possibility of the seismic gap hypothesis: earthquake hazard ... |
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| The Impact of Heat Release in Turbine Film Cooling |
JUN 2008 |
165 pages |
| Authors:
Dave S. Evans; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The Ultra Compact Combustor is a design that integrates a turbine vane into the combustor flow path. Because of the high fuel-to-air ratio and short combustor flow path, a significant potential exists for unburned fuel to enter the turbine. Using contemporary turbine cooling vane designs, the injection of oxygen-rich turbine cooling air into a combustor flow containing unburned fuel could result in heat release in the turbine and a large ... |
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| Revisiting the Nonlinear Response of a Plate to Acoustic Loading |
Apr-2008 |
14 pages |
| Authors:
Joseph J Hollkamp; Robert W Gordon; Timothy J Beberniss; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH ANALYTICAL STRUCTURAL MECHANICS BRANCH
|
| Accurate prediction of the structural response of stiffened aircraft skins to acoustic loading is necessary for the design of future Air Force vehicles. Response prediction requires time integration of nonlinear models. Recently, methods have emerged where a nonlinear finite element model is reduced to a low-order system of nonlinear equations to better enable the computations. Well-characterized experiments are needed to validate these methods. In a previous study, experimental data from ... |
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| Error Estimation for Three Turbulence Models: Incompressible Flow |
JAN 2008 |
27 pages |
| Authors:
Jr Vaughn Milton F.; ARMY RESEARCH DEVELOPMENT AND ENGINEERING COMMAND REDSTONE ARSENAL AL
|
| In order to facilitate the application of Computational Fluid Dynamics (CFD) tools by aerodynamic designers, an assessment of error was made for the Menter Shear Stress Transport (SST), Spalart-Allmaras, and Nichols-Nelson Hybrid (RANS/LES) SST turbulence models. The assessment was made for incompressible flow over a smooth flat plate of unit length. Correlations of the error in drag coefficient with initial grid point spacing, expressed in terms of y+, were discovered ... |
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| Continuum Modeling of Interface Failure |
DEC 2007 |
55 pages |
| Authors:
Robert P. Griffiths; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Two-dimensional continuum modeling and simulations were conducted to predict how the size, quantity, and stiffness of reinforcing particles such as carbon nanotubes (CNTs) affect failure mechanisms at the interface of composite structures. First, the strength model used the finite element method (FEM) on a slender composite beam with step-joint containing reinforcing particles to predict its critical stress-strain behavior at the joint interface under compressive axial load. Next, the fracture mechanics ... |
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| Experimental and Computational Observation of Radiometric Forces on a Plate (Postprint) |
12 JUN 2007 |
13 pages |
| Authors:
N. Selden; C. Ngalande; S. Gimelshein; A. Ketsdever; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
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| The radiometric force on several configurations of heated plates placed in a stagnant gas is examined experimentally on a high resolution thrust stand and numerically using the direct simulation Monte Carlo method. A wide range of pressures from 0.006Pa to 6Pa corresponding to Knudsen numbers from 20 to 0.02 is examined for nitrogen, argon, xenon, and helium test gases. It is shown that the force is maximum in the transition ... |
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| Feasibility Investigation into Strengthening of Timber Bridge Stringers |
MAY 2007 |
142 pages |
| Authors:
Anthony J. Lamanna; Arda Akbiyik; James C. Ray; Gerardo I. Velazquez; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| The majority of timber bridges in the United States are nearing the end of their service life. They exhibit several types of damage, which occurs in their structural elements such as timber stringers. The most commonly encountered damage type in timber stringers in bridge structures is horizontal splits. Researchers investigated the feasibility of repairing timber stringers that showed signs of horizontal splitting along the length of the member. Timber stringer ... |
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| The Resistance of Metallic Plates to Localized Impulse |
01-Mar-2007 |
30 pages |
| Authors:
Z Wei; D Knight; Y Chen; P Dudt; R K Elzey; Y Murty; H N Wadley; D T Queheillalt; K P Dharmasena; A G Evans; V S Deshpande; K Kiddy; CALIFORNIA UNIV SANTA BARBARA DEPT OF MATERIALS
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| The responses of metallic plates and sandwich panels to localized impulse are examined by using a dynamic plate test protocol supported by simulations. The fidelity of the simulation approach is assessed by comparing predictions of the deformations of a strong-honeycomb-core panel with measurements. The response is interpreted by comparing and contrasting the deformations with those experienced by the same sandwich panel (and an equivalent solid plate) subjected to a planar ... |
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| Night Vision Goggle Clip "Make vs. Buy" Study |
18 DEC 2006 |
9 pages |
| Authors:
Lee McCullough; NATIONAL CENTER FOR DEFENSE MANUFACTURING AND MACHINING LATROBE PA
|
| Letterkenny Army Depot "LEAD", located in Chambersburg PA, received an order to manufacture 12,000 night vision goggle "NVG" plates. These plates are used to mount the NVG to the Soldier's helmet. However, the quantities needed had increased over four fold from 12,000 to 52,000 "7,000 NVG plates per month" near the time of production. Based on these quantities, delivery dates, and current workload, LEAD requested the assistance of the National ... |
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| Functionally Graded Shape Memory Alloy Composites Optimized for Passive Vibration Control |
20 NOV 2006 |
23 pages |
| Authors:
Victor Birman; MISSOURI UNIV-ROLLA ENGINEERING EDUCATION CENTER
|
| The author has developed a methodology for the dynamic analysis of composite and isotropic plates supported by functionally graded shape memory alloy wires embedded in sleeves. The solution of the equations of motion is obtained for shear deformable plates using the first order shear deformation theory and for thin plates by the classical plate theory. Two designs of functionally graded shape memory alloy reinforcements are considered, including wires in sleeves ... |
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| Failure Analysis of a Cracked CH-47 Swashplate Rotating Ring, S/N BCW-1379 |
JUN 2006 |
28 pages |
| Authors:
Scott Grendahl; Russell Yocum; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The U.S. Aviation and Missile Command sent the U.S. Army Research Laboratory s Weapons and Materials Research Directorate three swashplate rotating rings from the CH-47 helicopter for investigation. The components were examined due to the presence of cracks found during routine overhaul. These cracks were on and adjacent to the bearing retention shoulder. One of these rotating rings, S/N BCW-1379, was included for a detailed failure analysis to determine the ... |
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| Effect of Side Jets in a Supersonic Flow Measured and Calculated on a Flat Plate and a Generic Missile Configuration |
May-2006 |
34 pages |
| Authors:
Anke Kovar; Erich Schulein; GERMAN AEROSPACE CENTER GOTTINGEN (GERMANY)
|
| An investigation on side jets in an M = 5.0 flow was conducted on a flat plate as well as on a generic missile configuration. Surface pressure measurements, oil flow visualisations, force measurements and associated numerical simulations gave insight into the interaction of different jet configurations and their influence on the efficiency of side jet control described by the amplification factor. The analysis of the data especially in the wake ... |
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| Comparison of Computational Electromagnetic Codes for Prediction of Low-Frequency Radar Cross Section |
MAR 2006 |
172 pages |
| Authors:
Paul C. Lash; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Radar cross section (RCS) prediction of full-scale aircraft is of interest to military planners for a variety of applications. Several computational electromagnetic codes for RCS prediction are available with differing features and capabilities. The goal of this research is to compare the capabilities of three computational electromagnetic codes for use in production of RCS signature assessments at low frequencies in terms of performance, accuracy, and features: Fast Illinois Solver Code ... |
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| Processing of Multifunctional Epoxy Resins Modified with Silicon Based Nanomaterials (PREPRINT) |
07 FEB 2006 |
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| Authors:
Amy R. Spero; D. Marchant; J. Mabry; Lisa Viculis; AIR FORCE RESEARCH LAB EDWARDS AFB CA
|
 | Improvements in thermal and physical properties of epoxy resin systems have been demonstrated in the past through the influence of fillers. However, these improvements often come with a significant cost to processability. This paper examines the influence of nanofillers on a multifunctional epoxy resin system in terms of processability and thermal properties. The nanocomposites explored included nanosilica, linear calcium silicate (wollastonite), and polyhedral oligomeric silsesquioxane (POSS) in CYCOM 977-3 resin. ... |
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| Development of K-Version of the Finite Element Method: A Robust Mathematical and Computational Procedure |
FEB 2006 |
31 pages |
| Authors:
J. N. Reddy; TEXAS A AND M UNIV COLLEGE STATION DEPT OF MECHANICAL ENGINEERING
|
| This report summarizes the research carried out under Grant F49620-03-1-0201 on the development of least-squares based finite element models of viscous compressible and incompressible flows as well as shear deformable plates and shells. The main objective of this research was to develop a robust and accurate computational methodology based on least-squares variational principles for the numerical solution of the equations governing plates and shells and viscous incompressible and compressible fluid ... |
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| Modeling of Progressive Damage in the Adhesive Bond Layers of Actuated Plates |
30 NOV 2005 |
54 pages |
| Authors:
Jr Robbins D. H.; MARYLAND UNIV COLLEGE PARK DEPT OF AEROSPACE ENGINEERING
|
| This report discusses finite element modeling of progressive damage in the adhesive bond layers of actuated plates and investigates the reduction in actuation capacity caused by the damaged bond layers. The primary challenge posed by this class of problems stems from the vast range of geometric scales that are represented, with the thickness of the adhesive layer representing the smallest scale, the overall thickness of the actuated plate representing the ... |
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| Apparatus for Changing the Attack Angle of a Cavitator on a Supercavatating Underwater Research Model |
18 JUL 2005 |
25 pages |
| Authors:
William H. Nedderman; DEPARTMENT OF THE NAVY WASHINGTON DC
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| This patent application discloses an apparatus for changing the angle of attack of a cavitator on a supercavitating underwater research model. The apparatus has a nose assembly that has a pivotable cavitator tilt plate, an actuator member and a drive system engaged with the actuator member to drive the actuator member so as to tilt the cavitator tilt plate to a desired angle. Power components are remotely located and accessible ... |
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| Rapid and Robust Dynamics-Based Nondestructive Method for Aerospace Structural Health Monitoring |
14 JUN 2005 |
37 pages |
| Authors:
Pizhong Qiao; Wahyu Lestari; INTEGRATED SMART STRUCTURES INC COPLEY OH
|
| Report developed under STTR contract for Topic F045-016-0125 addresses dynamic-based damage identification techniques for structural health monitoring (SHM) of aerospace structures. Two systems (i.e., the scanning laser vibrometer (SLV) and PVDF sensor) are used to acquire the dynamic information, and effective damage detection algorithms (e.g., the gapped smoothing method (GSM) and generalized fractal dimension (GFD) and schemes (e.g., the uniform load surface (ULS) and combined static/dynamic techniques) are developed to ... |
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| Experimental Investigation Into the Aerodynamic Ground Effect of a Tailless Chevron-Shaped UCAV |
JUN 2005 |
128 pages |
| Authors:
Brett L. Jones; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| This experimental study adequately identified the ground effect region of an unmanned combat air vehicle (UCAV). The AFIT 3' x 3' low-speed wind tunnel and a ground plane were used to simulate the forces and moments on a UCAV model in ground effect. The chevron planform used in this study was originally tested for stability and control and the following extends the already existing database to incude ground effects. The ... |
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| Localization of Deformation in Heterogeneous Solids Deformed at High Strain Rates |
31 JAN 2005 |
111 pages |
| Authors:
B. M. Love; R. C. Batra; VIRGINIA POLYTECHNIC INST BLACKSBURG
|
| Plane strain transient finite thermomechanical deformations of heat- conducting particulate composites comprised of circular tungsten particulates in nickel-iron matrix are analyzed using the finite element method to delineate the initiation and propagation of brittle/ductile failures by the nodal release technique. Each constituent and composites are modeled as strain-hardening, strain-rate-hardening and thermally-softening microporous materials. Values of material parameters of composites are derived by analyzing deformations of a representative volume element whose ... |
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| Design of a Novel, Multi-Port-Addressable Bioaerosol Collection System |
17 NOV 2004 |
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| Authors:
Trina Vian; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Characteristics and Sampling Efficiencies of Two Impactor Bioaerosol Samplers: MAS-100(Registered) (Microbial Air Monitoring System) and Single-Stage Andersen Viable Microbial Samplers |
OCT 2004 |
19 pages |
| Authors:
K. A. Hottell; Jana Kesavan; EDGEWOOD CHEMICAL BIOLOGICAL CENTER ABERDEEN PROVING GROUND MD RESEARCH AND TECHNOLOGY DIR
|
| Sampler characteristics and efficiencies of two impactor type biological air samplers were determined. Both impactors are based on the principle of air accelerating through an entry plate with critically sized orifices and inertially impacting onto a surface below. A petri dish with agar is used as the impaction surface for these samplers. The MAS-l00 is a single- stage impactor that aspirates air through a 400-hole perforated entry plate onto an ... |
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| Properties of Planar Surface Wave Excited Plasma |
07 APR 2004 |
2 pages |
| Authors:
Masashi Kando; SHIZUOKA UNIV HAMAMATSU (JAPAN)
|
| The properties of the planar surface wave plasma are discussed from the view point of electron heating in the plasma at the low pressure, referring to the experimental evidences. The role of the dielectric plate is considered. The plasma density profiles in the radial direction can be modified by controlling the microwave in the dielectric plate. |
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| The Evaluation of the Damping Characteristics of a Hard Coating on Titanium |
MAR 2004 |
116 pages |
| Authors:
Christopher M. Blackwell; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Engine failures due to fatigue have cost the Air Force an estimated $400 million dollars per year over the past two decades (Garrison, 2001). Damping treatments capable of reducing the internal stresses of fan and turbine blades to levels where fatigue is less likely to occur have the potential for reducing cost while enhancing reliability. This research evaluates the damping characteristics of magnesium aluminate spinel, MgO+Al2O3, (mag spinel) on titanium ... |
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| Gravity-Actuated Submarine Antenna |
11 FEB 2004 |
28 pages |
| Authors:
David F. Rivera; DEPARTMENT OF THE NAVY WASHINGTON DC
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| An antenna including a feed tube with radial fins and 7 circular plates at the ends of the tube and fins thereby forming a boundary for a plurality of resonant cavities. Curved plates, connected to the tube by switches of a switching system, partially encompass and subtend to the length of the tube. Interior to the tube, a transmission line from an end plate terminus conducts radio-frequency energy from the ... |
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| Ballistic Performance of Titanium Alloys: Ti-6Al-4V Versus Russian Titanium |
FEB 2004 |
25 pages |
| Authors:
Tyrone L. Jones; OAK RIDGE INST FOR SCIENCE AND EDUCATION ABERDEEN PROVING GROUND MD
|
| A Ti-6A1-4V baseline plate and a Russian titanium alloy plates were ballistically tested against .30-cal armor-piercing (AP) M2 rounds. The V(50) ballistic limit of each plate was determined and compared to the MIL-DTL-46077F V(50) ballistic acceptance chart for Ti-6Al-4V alloy. Based on these results, no clear ballistic performance advantage would be achieved by using the Russian titanium alloy against 0.30-cal AP M2 threats. |
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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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| PA116/171 Containers ona Wood Pallet With Metal Top Adapter, MIL-STD- 1660, First Article Tests |
SEP 2003 |
26 pages |
| Authors:
Jeffery L. Dugan; ARMY DEFENSE AMMUNITION CENTER MCALESTER OK VALIDATION ENGINEERING DIV
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| The U.S. Army Defense Ammunition Center (DAC), Validation Engineering Division (SJMAC-DEV) conducted First Article Tests per MIL-STD-1660, "Design Criteria for Ammunition Unit Loads" on the PA116/171 containers on a wood pallet with metal top adapter provided by Alliant Tech Ordnance and Ground Systems LLC of Plymouth, MN. Two separate containers were tested with total weights of 2,470 lbs each. The tests accomplished on the test units were the stacking, repetitive ... |
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| Radar Absorbing Material Design |
SEP 2003 |
83 pages |
| Authors:
Cihangir K. Yuzcelik; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| Low observable platforms have extremely low radar cross section specifications that cannot be achieved by shaping alone. The application of radar absorbing material is necessary, in which case the appropriate constitutive parameters and thickness must be selected. The universal design chart gives combinations of mu, epsilon and tau that provide zero specular reflection at normal incidence. Three different backing materials were used to generate the charts: (1) perfect electric conductor, ... |
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| The Analytical Method of Investigation of Faraday Chiral Media |
11 JUN 2003 |
3 pages |
| Authors:
K. Vytovtov; DNIPROPETROVSK NATIONAL UNIV (UKRAINE)DEPT OF RADIOPHYSICS
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| A plane-parallel homogeneous bianisotropic plate under an oblique incidence of a plane harmonic wave is considered. The bianisotropy axis is not coincide with a normal to a plate. The propagation and reflection coefficients are found in the analytical form. |
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| Analytical Investigation of Periodic Media with Negative Parameters |
11 JUN 2003 |
4 pages |
| Authors:
K. Vytovtov; DNIPROPETROVSK NATIONAL UNIV (UKRAINE)DEPT OF RADIOPHYSICS
|
| The electromagnetic properties of an artificial layered material with negative permittivity and permibility are studied analytically. To analyses the translation matrix method is employed The translation matrix for multilayered structure is found in analytical form. The reflection and propagation coefficients of multilayered plate arc written in analytical form. The propagation conditions of a wave within periodic layered structure with negative parameters are obtained in analytical form. |
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| Small Crack Growth at Pin Loaded Holes |
JUN 2003 |
139 pages |
| Authors:
Arvind Nagar; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH AIR VEHICLES DIRECTORATE
|
| This report describes the results of an experimental study conducted to verify analytical methods for small crack growth prediction at pin-loaded holes under varying load transfer rates. The study was conducted on 2024-T3 joint specimens with an initial 0.003-inch radial thru crack under constant amplitude cyclic and spectrum loads. The test specimens were joined using three different types of doublers. Crack growth data in the small crack regime and the ... |
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| Analytic Expression of the Buckling Loads for Stiffened Plates with Bulb-Flat Flanges |
JUN 2003 |
121 pages |
| Authors:
Archie Wilmer III.; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MATHEMATICS
|
| The subject of this research is the buckling behavior of a simply supported rectangular plate, with a bulb-flat stiffener attached to one side of the plate The plate structure is subjected to axial compression that increases to the buckling load, The stiffener cross-section has a thin web and a bulb-flat flange that extends to one side of the web, Results of the investigation include planar property formulas% for the asymmetric ... |
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| Corrosion Mechanisms of UNS N04400 in Sea Water |
MAR 2003 |
24 pages |
| Authors:
Jason S. Lee; Kristine Lowe; RIchard I. Ray; J. Jones-Meehan; Brenda J. Little; NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
|
| Pitting and dealloying were observed when 70Ni/30Cu (UNS N04400) welded plates were exposed to artificial seawater containing sulfate-reducing bacteria. Attempts were made to differentiate biotic and abiotic corrosion mechanisms. Experiments were conducted in alternating aerobic/anaerobic conditions in the presence of inorganic sulfide and sulfate-reducing bacteria over the course of five months. |
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| Multifunctional Mechatronic Materials |
21 FEB 2003 |
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| Authors:
Anthony Evans; PRINCETON UNIV NJ OFFICE OF RESEARCH AND PROJECT ADMINISTRATION
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| Contributions have been made in two basic areas: ultralight structures based on sandwich panels with truss and textile cores, and high authority actuating structures based on the properties of the Kagome system. This final report contains the following studies: (1) Effective Properties of the Octet-truss Lattice Material, by V.S. Deshpande, N.A. Fleck, and M.F. Ashby; (2) Kagome Plate Structures for Actuation, by R.G. Hutchinson, N. Wicks, A.G. Evans, N.A. Fleck, ... |
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| A Method for Estimating the Mechanical Properties of a Solid Material Subjected to Insonification - Part 1: Theory |
06 DEC 2002 |
38 pages |
| Authors:
Andrew J. Hull; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
|
| A theoretical inverse method is develop to measure the complex, frequency deponent dilatational and shear wavespeeds that are present in isotropic thick plates. Once this wavespeeds are identified, the complex, frequency dependent Young's and shear moduli and complex, frequency-dependent Poisson's ratio can he estimated. Simulations are presented both with and without noise to show how the method works and how the measurement error affect the analysis results. |
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| Shock Studies of Ceramics |
JUN 2002 |
8 pages |
| Authors:
W. G. Proud; J. E. Field; CAMBRIDGE UNIV (UNITED KINGDOM) DEPT OF PHYSICS
|
| The report covers the 3 month visit of Dr. D. Dandekar of ARL, USA to the Cavendish Laboratory. The project involved an exchange of ideas in the area of shock physics and the design, sample preparation and testing of various materials in the plate-impact facility. The report describes the plate impact facility and the techniques used. Data is reported on a series of spall experiments on PMMA (polymethyl methacrylate). Samples ... |
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| Estimation of Ambient Radiation Temperature for Emissivity-Corrected Thermography |
25 OCT 2001 |
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| Authors:
K. Otsuka; S. Okada; T. Togawa; TOKYO MEDICAL AND DENTAL UNIV (JAPAN) INST OF BIOMATERIALS AND BIOENGINEERING
|
| A non-contact method for the measurement of emissivity, and emissivity-corrected temperatures has been developed, where the ambient radiation-temperature is changed in a discontinuous way. When the ambient radiation-temperature is unchanged quickly, so that the surface temperature of the object can be assumed to be unchanged, the radiometer output before, and immediately after that change can be expressed as two simultaneous equations. The temperature and emissivity of the surface can be ... |
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| High Reynolds Number Boundary Layer Scaling on a Large Hydrofoil (HIFOIL) |
OCT 2001 |
34 pages |
| Authors:
Wesley H. Brewer; Joel T. Park; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| Velocity profiles were measured on a large hydrofoil model to investigate the Reynolds number dependence in a range of 6x1O(exp 6) to 6xlO(exp 7). The friction velocity and skin friction are computed directly from the velocity measurements using the universal velocity-distribution law. The boundary layer profiles are also numerically integrated to yield displacement and momentum thickness, as a function of Reynolds number. Measurements from the foil pressure-side, which is essentially ... |
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| Theoretical and Experimental Studies of Vibro-Acoustic Systems |
17 AUG 2001 |
185 pages |
| Authors:
Jonathan K. Wong; David W. Miller; MASSACHUSETTS INST OF TECH CAMBRIDGE SPACE SYSTEMS LAB
|
| Structural-acoustic vibration is one of the major sources of payload failure during launch. Past research on the topic of structural-acoustic vibration control has focused on actuating a single structural layer to minimize the amount of energy flowing across the boundary. This thesis investigates the use of a dual layer approach to address the structural-acoustic problem and compares the results to a single layer approach. Four different controller configurations were used ... |
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| Static and Fatigue Testing of Mechanical Life Extension Options for Plates Containing Elongated Holes |
AUG 2001 |
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| Authors:
Rebecca L. Evans; Manfred Heller; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AERONAUTICAL AND MARITIME RESEARCH LAB
|
| F-111 representative static and fatigue testing has been undertaken to assess the suitability of AMRL designed stress-bridge and interference-fit plug options for the fatigue life enhancement of plates containing non-circular elongated holes of 2:1 aspect ratio. For the stress-bridge design, an improvement in strain concentration factor of 38% was demonstrated for lower magnitude remote loads as compared to plates with unenhanced holes. Conversely, during typical high loads, the alternating strain ... |
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| Feasibility Study of a Smart Submunition: Deployment from a Conventional Weapon |
JUN 2001 |
41 pages |
| Authors:
Norman M. Werelsy; Darryll J. Pines; MARYLAND UNIV COLLEGE PARK DEPT OF AEROSPACE ENGINEERING
|
| This report details the smart autonomous rotorcraft submunition (SMARS) designed for deployment from a conventional munition. SMARS was developed in response to requirements defined in an initial meeting with Mr. Michael Hollis of the U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland, April 18,2000. The primary goal of this initial design was to develop a rotorcraft that could be housed inside a conventional munition and carry a payload of 1.36 ... |
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| Waves and Vibrations in Electroplated Piezoelectric Plates and Substrate Systems |
09 FEB 2001 |
5 pages |
| Authors:
Peter C. Lee; PRINCETON UNIV NJ DEPT OF CIVIL ENGINEERING AND OPERATIONS RESEARCH
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| In the present research, a new, infinite system of plate equations is obtained. They are applicable to piezoelectric plates of any crystal symmetry and requiring no correction factors. Firstly, a system of first-order plate equations is extracted from the infinite system, and they are employed to study the thickness shear and flexure vibrations of rectangular plates of AT- and SC- cuts of quartz and are shown to give accurate predictions ... |
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| Composite Structures, Volume 50, No. 4, December 2000. Special Issue: Experimental Validation of Theoretical Predictions for Composite Structures. Composite Structures Workshop Held in Monash University, Melbourne, Australia on 18-19 Nov 1999 |
08 JAN 2001 |
126 pages |
| Authors:
MONASH UNIV CLAYTON (AUSTRALIA) DEPT OF MECHANICAL ENGINEERING
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| Conference Proceedings to Include the Following: "Experience With the Finite Element Modelling of a Full-Scale Test of a Composite Aircraft Control Surface" "Material Characterization of Laminated Composite Plates Via Static Testing" "Evaluating the Soundness of Bonding Using Shearography" "Combined Numerical-Experimental Model for the Identification of Mechanical Properties of Laminated Structures" "Control of Beam Vibrations by Means of Piezoelectric Devices: Theory and Experiments" "Impact Energy Absorption Characteristics of Composite Structures" "Experimental ... |
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| Identification of Novel Secreted Molecules Prostate Cancer |
DEC 2000 |
32 pages |
| Authors:
Phillip Koeffler; CEDARS-SINAI MEDICAL CENTER LOS ANGELESCA
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| We have developed an approach to isolate new tumor markers of prostate cancer. In order to identify genes encoding secrete protein, we have modified the signal sequence trap technique, using the SUC 2 gene encoding a secrete protein of yeast. Only the yeast which have been transformed with cDNAs containing secretory signal sequences ca row into colonies on the plates which contain sucrose as the only source of sugar. Early ... |
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