| Damping Studies of Ceramic Reinforced Aluminum. |
1992 |
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| Authors:
Catherine R. Wong; Stephen Holcomb; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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 | This paper concerned mmc in some important way and contained information about, utilized, or discussed these subjects: basic topics:, data, dr mmc, experimental, mmc, mmc data materials and material types:, (al2o3)p/6061, (sic)p/a356, 6061 matrix, a356 matrix, al matrix, al2o3 particulates, al2o3/6061, al2o3/al, ceramic particulates, particulates, sic particulates, sic/a356, sic/al material characteristics and data fields:, damping capacity, damping capacity data, modulus data, shear modulus, stiffness, storage modulus, thermal properties data, thermal ... |
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| Mixed Model Fatigue Crack Growth Behavior in a High Strength Steel |
NOV 91 |
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| Authors:
Richard E. Link; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| Most of the currently available methods for predicting fatigue crack growth in structures do not consider effects due to mixed-mode loading. This is partly due to the limited information available concerning the fatigue crack growth under mixed mode loading. Previous investigations of mixed mode effects on fatigue crack growth have shown that under combined opening and in-plane shear loading, the cracks turn abruptly so that the in-plane shear mode is ... |
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| Effects of Cyclic Loading on the Deformation and Elastic-Plastic Fracture behavior of a Cast Stainless Steel |
OCT 91 |
50 pages |
| Authors:
J. A. Joyce; E. M. Hackett; C. Roe; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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 | Tests conducted in Japan as part of the High Level Vibration Test (HLVT) program for reactor piping systems revealed fatigue crack growth in a cast stainless steel pipe elbow. Material property data was developed to characterize cyclic deformation, cyclic elastic-plastic crack growth and ductile tearing resistance in the pipe elbow material. The tests conducted included monotonic and cyclic tensile tests, monotonic J-R curve tests, and cyclic elastic and elastic plastic ... |
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| Bimetallic Tubulars Via Spray Forming |
AUG 91 |
26 pages |
| Authors:
Paul Kelley; Angela Moran; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| High deposition rate spray forming is a new technology which has been developed to reduce the costs and to improve the performance of a wide variety of engineering alloys. The purpose of this investigation was to demonstrate the ability to produce layered bimetallic structures via the spray forming process. Copper tubulars were used as collectors for spray deposited alloy 625. The collectors were varied in thickness and various interfacial alloys ... |
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| Development of Neodymium and Er3Ni Regenerator Materials |
AUG 91 |
21 pages |
| Authors:
Louis F. Aprigliano; Geoffrey Green; James Chafe; Lisa O'Conner; Frank Biancanello; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| Neodymium and Er3Ni powders were produced and examined as possible candidates for use as regenerator matrices in the regenerative heat exchanger of the Gifford-McMahon cycle refrigerator. In the case of Er3Ni, crushed powders were brittle and angular in shape, molten salt produced spheres were heavily oxidized, and gas atomized powder had a low yield (3%) and a large fraction of hollow particles. Neodymium powder, which was produced by the rotating ... |
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| Analysis of Strain Dependent Damping in Materials via Modeling of Material Point Hysteresis |
JUL 91 |
72 pages |
| Authors:
E. J. Graesser; C. R. Wong; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| A constitutive relationship was used to model the cyclic material response of damping test samples in separate bending and torsion configurations. This was done in order to better understand variations in reported values of damping for materials possessing strain dependent characteristics. The constitutive equations are based on a model of shape memory alloy stress strain behavior and have been adapted especially for the study of nonlinear hysteresis and the problem ... |
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| An Optical Roughness Sensor for the Real Time Determination of Spray Formed Preform Quality |
JUL 91 |
34 pages |
| Authors:
Rochelle D. Payne; Angela L. Moran; Craig J. Madden; Paul Kelley; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| The emphasis in this paper is on the application of spray forming control strategies towards the use of a laser stripe sensor for the calculation of root mean square (RMS) preform surface roughness. The objective of this study is to correlate this calculation of roughness with the preform quality. Spray forming is a relatively new processing technique in which a stream of molten metal is atomized by an inert gas, ... |
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| An Intelligent Control Strategy for the Spray Forming Process |
JUN 91 |
19 pages |
| Authors:
Angela L. Moran; Craig J. Madden; M. A. Matteson Jr.; Paul Kelley; Dawn White; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| A control system incorporating a fuzzy logic inference engine and optical sensors has been developed for the spray forming facility at the David Taylor Research Center. An imaging system employing laser illumination and a high speed CCD camera provides critical on-line preform surface roughness and rate of growth information. A fuzzy logic controller utilizes a rule set to translate visual information into a form that can be reviewed by the ... |
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| Vibration Damping Response of Composite Materials |
APR 91 |
302 pages |
| Authors:
Roger M. Crane; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| This report involves the investigation of the mechanical vibration damping characteristics of glass/epoxy and graphite/epoxy composite materials. The objective was to develop an analytical model which incorporates the frequency dependence of the vibration damping loss factor and to experimentally characterize the loss factor for frequencies up to 100 Hz. Numerous mathematical models have been proposed to determine the loss factor of composites, including micromechanical, macromechanical and structure models. Of these ... |
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| U.S. Navy Shipboard-Generated Plastic Waste Pilot Recycling Program |
MAR 91 |
62 pages |
| Authors:
Leslie B. Middleton; Jery Y. Huntley; Jonathan J. Burgiel; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| From April 1990 through January 1991, the feasibility of recycling Navy shipboard-generated plastic wastes was explored. Normally, plastic wastes are source separated aboard Navy ships and retained for shoreside disposal in accordance with new fleet requirements implementing MARPOL Annex V that prohibits the discharge of plastics at sea. Over 23,000 pounds of shipboard plastic wastes from USS Lexington (AVT 16) and ships from the Norfolk Naval Base were recycled into ... |
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| Acoustic behavior of Negative Poisson's Ratio Materials |
MAR 91 |
31 pages |
| Authors:
Barbara Howell; Pat Prendergast; Larry Hansen; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| Negative Poisson's ratio (NPR) materials have been predicted to have unusual acoustic properties. To measure this effect, polyurethane foam was chosen to serve as a model system. Negative Poisson's ratio materials were produced from open cell, reticulated polyurethane foams by heat setting the foam which was compressed in three dimensions to a volume smaller by the factor 3.7 than the original volume. Acoustic tests comparing the reflection properties of the ... |
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| Damping Studies of Ceramic Reinforced Aluminum |
MAR 91 |
24 pages |
| Authors:
Catherine R. Wong; Stephen Holcomb; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Ceramic reinforced aluminum alloys exhibit a unique combination of mechanical properties not found in monolithic aluminum alloys. The addition of high modulus ceramic particles to conventional aluminum alloys results in increased strength, elastic modulus and wear resistance. Because of these desirable engineering properties the damping capacity and storage modulus was measured as a function of ceramic volume fraction, temperature and frequency. Two Al-Si-Mg matrix composites were studied which included the ... |
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| The Relationship of Traditional Damping Measures for Materials with High Damping Capacity |
JAN 91 |
46 pages |
| Authors:
E. J. Graesser; C. R. Wong; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| Simply stated, damping is the dissipation of energy in vibrating systems which results in either the control of the amplitude of oscillations or their eventual decay. In mechanical systems damping can be classified as passive or active. Active damping uses externally applied feedback control forces to limit the deformation and motion of large structural configurations. Passive damping makes use of properties which are inherent to the system and which arise ... |
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| The Effect of Weld Metal Strength Mismatch on the Deformation and Fracture Behavior of Steel Butt Weldments |
JAN 91 |
59 pages |
| Authors:
Mark T. Kirk; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| Considerable Naval and industrial experience has indicated the engineering utility of using weld metal having strength greater than the plates being joined (over-matching). Overmatching shields the weld region, which typically has lower toughness than the plate and is often the site of defects, from the high strains that develop during an overload. This practical advantage, coupled with the ease of achieving overmatch in lower strength steel alloys (80 ksi yield ... |
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| Development of ASTM D2274 Reference Fuels Based on 1,2,5 Trimethylpyrrole in n-Dodecane. Interim Report: Effect of Preparation Procedures and Trimethylpyrrole Aging |
DEC 90 |
40 pages |
| Authors:
M. D. Klinkhammer; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| Solutions of 1,2,5-trimethylpyrrole (TMP) in n-dodecane were evaluated for use as reference fuels to produce known amounts of sediment. Tests were run in accordance with ASTM D2274, Test Method for Oxidation Stability of Distillate Fuel Oil (Accelerated Method). Each of four test operators determined the amount of sediment formed as a function of TMP concentration (0 to 150 milligrams per 100 milliliters) and of D2274 stress time (4 to 96 ... |
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| Fracture Behavior of Ultra-Low-Carbon Steel Plate and Heat-Affected- Zone |
DEC 90 |
98 pages |
| Authors:
M. G. Vassilaros; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| This report describes research carried out to investigate the fracture of ultra-low-carbon bainitic steels. Eight materials have been evaluated using notched-bar bend tests, tensile strength tests and Charpy V- notch impact tests, which were performed over a range of temperatures from -1965 C to +1005 C. These tests measured the cleavage fracture strength and the ductility to brittleness transition temperature under impact loading. The materials evaluated had carbon levels of ... |
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| Ultra-Low Carbon Bainitic Steels for Heavy Plate Applications |
DEC 90 |
52 pages |
| Authors:
C. I. Garcia; A. J. DeArdo; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| A new family of ultra-low carbon bainitic (ULCB) steels for heavy plate applications has been investigated. These new steels have been developed as possible candidates to replace traditionally heat treated HTS and HY steels. One major attraction of the ULCB steels is that they do not need to be heat treated to obtain their final mechanical properties. The ULCB steels obtain their high strength and high resistance to both ductile ... |
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| Microstructural Features Controlling Ductile-to-Brittle Transition Behavior in High-Strength, Martensitic Steel Weld Metals |
OCT 90 |
122 pages |
| Authors:
J. J. DeLoach Jr; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| An investigation of the transition behavior of high strength steel, martensitic weld metals was conducted. The objective of the investigation was to identify the specific microstructural features that control ductile-brittle transition in these weld metals. The approach systematically combined experimental measurements and observations with the use of analytical expressions. Charpy V-notch (CVN) properties, tensile properties, and cleavage fracture stress (sigma c) were generated over a range of temperatures. The critical ... |
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| A Comparison of the Compression Response of Thick (6.35mm) and Thin (1. 60mm) Dry and Moisture Saturated AS4/3501-6 Laminates |
OCT 90 |
122 pages |
| Authors:
Karin Gripple; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| The compression response of thick (6.35 mm) and thin (1.60mm) (O2/90) subs AS4/3501-6 laminates was compared for material in the dry and moisture saturated conditions. The thick specimens failed at 1055 MPa dry and 740 MPa wet. Comparable strengths for the thin specimens were 1090 and 957 MPa. There was no statistical difference in strength for the dry material of either thickness. The thick specimens absorbed significantly more water than ... |
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| Minimum Release of Tributyltin to Prevent Macrofouling |
OCT 90 |
22 pages |
| Authors:
James W. Mihm; George I. Loeb; Elizabeth G. Haslbeck; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| The minimum release of tri-and dibutyltin has been determined for both barnacles and hydrozoans. The test method involved perfusing a known flux of biocide through a polycarbonate membrane filter with the downstream surface of the membrane exposed to a natural population of fouling organisms. No minimum release could be calculated for the dibutyltin because the flux rates were not high enough to achieve a zero fouling condition. |
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| Electrochemical Impedance of Organic Coated Steel; Final Report. Correlation of Impedance Parameters with Long-Term Coating Performance |
SEP 90 |
48 pages |
| Authors:
John N. Murray; Harvey P. Hack; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| This final report presents a general overview of the use of Electrochemical Impedance Spectroscopy (EIS) as it applies to the evaluation of organic coated steels exposed to aerated, artificial (ASTM) sea water. The testing was performed over roughly a 6-year span with some samples subjected to immersion testing for up to 4 years. Three project reports have been previously issued covering: (a) the initial test efforts, (b) a summary style ... |
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| Procedure for a Drop Tower Testing of Shallow Cracked Single Edge Notched Band Specimens Jun 89-Feb 90 |
JUL 90 |
54 pages |
| Authors:
M. T. Kirk; J. P. Waskey; R. H. Dodds Jr; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Underprediction of the reserve capacity of structures against fracture often result from use of conventional initiation fracture toughness values measured using deeply cracked bend specimens. Conversely, favorable comparisons between prediction and structural fracture behavior are reported when predictions are based on toughness values measured so that the crack tip constraint and loading rate closely match those experienced in service. Thus, considerable attention has been paid to elevated fracture initiation resistance ... |
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| Influence of Expanding Monomer on Carbon Fiber Reinforced Epoxy Composites |
JUN 90 |
25 pages |
| Authors:
Barbara F. Howell; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| In this investigation it was confirmed that copolymerization of dinorbornene spiroothocarbonate (DNSOC) with expoxy can eliminate sample shrinkage and even produce sample expansion. To maximize control of shrinkage, it is important to bring epoxy to the gel stage before the DNSOC begins to copolymerize. Embedded single filament tensile test results were compared for samples containing DGEBA-epoxy cured with m-phenylene diamine (mPDA) with those for DNSOC-epoxy cured with m-phenylene diamene (mPDA) ... |
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| Synthesis and Property Evaluation of Y-Ba(2)-Cu(3)-O(6+x) Superconductors |
JUN 90 |
28 pages |
| Authors:
A. S. Rao; O. P. Arora; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Superconducting YBa2Cu3O6+x powders were synthesized for obtaining fine particles of uniform size using solid state chemical reaction, coprecipitation and copper oxide coating with yttrium and barium oxalate or carbonate methods. The powders obtained from all three different routes showed superconductivity; however, the Tc values for the as synthesized powders via. the solid state and copper oxide coating methods were 90 K and the oxalate and carbonate derived powders was 80 ... |
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| Development of Low-Carbon, Copper-Strengthened HSLA Steel Plate for Naval Ship Construction |
JUN 90 |
23 pages |
| Authors:
Ernest J. Czyryca; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Modern warships designs require an increased utilization of high strength, alloy steel plate for weight reduction, stability, increased payload, and increased mobility. Naval ship structures are subjected to a complex spectrum of loads and service environments, and the structural steels and welding materials used in hull fabrication must demonstrate high fracture toughness for these extreme service conditions. The welding of HY-series hig |
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| Intelligent Processing for Spray Metal Manufacturing |
JUN 90 |
20 pages |
| Authors:
Angela L. Moran; Dawn R. White; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| A program to implement real time sensing and control of spray formed preform conditions is underway at the David Taylor Research Center. The objective of the program is to develop sensor and control technology to monitor the critical process conditions and to modify parameters during the spray forming process to produce components with repeatable microstructural quality. This task has been divided into two phases, the first of which entails development ... |
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| Effect of Additives on the Morphology and Superconductivity of YBa(2) Cu(3)O(6+x) Ceramic Superconductors |
MAY 90 |
35 pages |
| Authors:
A. S. Rao; L. F. Aprigliano; O. P. Arora; L. S. O'Connor; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Superplastic deformation is being studied as a means to turn the new ceramic superconductors into useful Naval hardware. Superplastic deformation can occur when a small grained material is subjected to stress at temperatures that are at least a half of their melting point. The ceramic superconductors, of which YBa2Cu3O6+x is typical, require sintering treatments to create reasonably dense materials. However, sintering can result in a degree of grain growth that ... |
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| Defect Area Determination of Organic Coated Steels in Seawater Using the Breakpoint Frequency Method |
MAR 90 |
38 pages |
| Authors:
Harvey P. Hack; John R. Scully; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Coating breakdown is a major maintenance cost on ships. It is therefore desirable to have a rapid technique for predicting or evaluating coating performance nondestructively. A method for simply determining the extent of coating breakdown would therefore be of great use to the Navy. The breakpoint frequency method is described which allows determination of the electrochemically active area of a coated metal seawater. A computer model is used to explain ... |
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| Method for Evaluating the High Strain-Rate Compressive Properties of Thick Composite Laminates |
MAR 90 |
24 pages |
| Authors:
D. M. Montiel; C. J. Williams; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| A test apparatus and methodology developed to obtain high strain-rate compressive mechanical properties of various fiber-reinforced composite materials is described. This direct compression method utilized a drop tower to impart a load at dynamic rates to the test fixture. Uniform specimen loading was accomplished through the use of aligned guide rails to constrain all but the vertical motion of a free-sliding impactor. Specimen endcaps, specific to thick- section testing, were ... |
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| Engineering Design and Development of Portable Smoke Curtains |
FEB 90 |
29 pages |
| Authors:
Lisandro Vazquez de Jesus; Richard Carey; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Four portable smoke curtain prototypes were developed and evaluated in a combined effort between this Center and the Naval Research Laboratory. The portable smoke curtain evaluations were conducted on ALBERT E. WATTS at the United States Coast Guard Fire and Safety Detachment, Mobile Alabama. Two designs effectively controlled the spread of smoke -- the two-strip design for use in archways and doors and the blanket design for use on hatches. ... |
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| A Framework to Correlate a/W Ratio Effects on Elastic-Plastic Fracture Toughness (J sub c) |
FEB 90 |
44 pages |
| Authors:
R. H. Dodds Jr.; T. L. Anderson; M. T. Kirk; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Single edge-notched bend (SENB) specimens containing shallow cracks (al W < 0.2) are commonly employed for fracture testing of ferritic material in the lower-transition region where extensive plasticity (but no significant ductile crack growth) precedes unstable fracture. Critical J-values (Jc) for shallow crack specimens are significantly larger (factor of 2-3) than the Jc- values for corresponding deep crack specimens at identical temperatures. The increase of fracture toughness arises from the ... |
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| Damping Capacity of Aluminum 6061- Indium Alloys |
JAN 90 |
27 pages |
| Authors:
C. R. Wong; O. Diehm; D. C. Van Aken; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Monotectic Al-6061 alloys containing between 0 and 5.2 volume percent indium and pure indium samples were fabricated. Each sample was characterized by metallographic and analytical electron microscopy and the damping capacity and storage modulus were measured. The model proposed by L.G. Nielsen was used to calculate the damping capacity and storage modulus of the alloys using the damping capacity and storage modulus of the constituents. The damping capacity of the ... |
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| Development of a Method to Measure Organotin Release Rates |
DEC 89 |
204 pages |
| Authors:
L. L. Copeland; K. C. Burns; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Organotin-containing paints provide excellent protection from fouling organisms, but they are toxic to nontarget organisms. Therefore, the Navy has pursued the development of paints with a very low release of tributyltin. Several methods have been used to determine the release rate of tributyltin from antifouling paint systems, with no standardization or correlation between the methods. A reliable laboratory method is important in comparing and ranking paints. Our initial attempts to ... |
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| Damping Loss Factor Determination of Glass and Graphite Epoxy Laminated Composites Using Vertically Oriented Cantilever Beams |
NOV 89 |
57 pages |
| Authors:
Roger M. Crane; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Material damping of laminated composites is experimentally determined using a cantilever beam test with an impulse excitation. The beam is oriented vertically as opposed to the traditional horizontal orientation. Data acquisition and manipulation is carried out using an IBM PC-AT with a high speed, A/D board and analysis software. Unidirectional continuous fiber 0, 90 and + or - 45 degree laminates were fabricated from glass/epoxy (Hercules S2- Glass/3501-6) and graphite/epoxy ... |
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| A Study of Variables Affecting Results in the D2274 Accelerated Stability Test. Part 3. Effects of Selected Physical Variables |
NOV 89 |
57 pages |
| Authors:
E. W. White; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Physical variables were examined to determine their effects on the formation or determination of the insolubles in the ASTM D2274 accelerated stability test. The physical variables that could affect the aging step are: bubbler geometry, the oxygen release depth, the fuel volume, the ratio of wetted surface to fuel volume, the age of the oxidation cell in the temperature bath, and the responsiveness of the bath. We examined the following ... |
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| Compression Testing of Thick-Section Composite Materials |
01 OCT 89 |
42 pages |
| Authors:
E. T. Camponeschi Jr; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Interest in the compressive response of fiber-reinforced composite materials has resulted in numerous research programs addressing the theoretical and experimental response of composites subjected to compressive loading. These research programs have dealt exclusively with the response of composite materials 6.4 mm (0.25 inches) in thickness and less. As composite materials become more attractive for use in large Navy structures, the need to understand the mechanical response of composites greater than ... |
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| Through-Thickness Strain Response of Thick Composites in Compression |
05 SEP 89 |
40 pages |
| Authors:
Eugene T. Camponeschi Jr; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| With the continued success of composite materials in high performance structures, new applications for Navy primary structure are being identified. Many of these applications require designs with composite materials having section thicknesses greater than those that have been used and studied to date. Along with this interest in thick composite structures comes the need for full three-dimensional stress analysis. The limits and accuracy of existing three- dimensional data bases will ... |
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| Damping Loss Factor Determination of Glass and Graphite Fiber Composites |
01 SEP 89 |
41 pages |
| Authors:
Roger M. Crane; Jojn W. Gillespie Jr; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Material damping of laminated composites is experimentally determined using a cantilever beam test with an impulse excitation. Data acquisition and manipulation is carried out using both an IBM PC-AT and a GenRad 2500 Series FFT Analyzer. Unidirectional continuous fiber 0 and 90 degree laminates were fabricated from glass/epoxy (Hercules S2-Glass/3501-6), graphite/epoxy (Hercules AS4/3501-6) and graphite/polyetheretherketone (ICI AS4/PEEK (APC-2)) to investigate the effect of fiber and matrix properties as a function ... |
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| Plasmon Excitation in the Scattering of Electromagnetic Waves from Good Conductors |
JUL 89 |
19 pages |
| Authors:
Clifford R. Schumacher; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Excellent Drude model fits were reported Kramers-Kroning analysis of measurements of the optical constants of 15 metals--Ti, Fe, Co, Ni, Pt, V, Pd, W, Pb, Cu, only provide excellent fits to the measured values of the conductivity but also were shown to predict the frequency dependence of the dielectric constant. All static values of the dielectric constant of these 15 metals were negative and very large, but increased monotonically with ... |
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| Instrumented Impact Testing of Fabric-Reinforced Composite Materials |
MAY 89 |
43 pages |
| Authors:
T. D. Juska; R. M. Crane; T. Mixon; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Instrumented impact and ultrasonic inspection were used to assess the impact damage resistance of six fabric-reinforced laminates. Polyester and vinylester resins reinforced with woven roving, biaxial reinforcement, and glass/Kevlar hybrid were evaluated. Biaxial fabric reinforced resins had the best impact resistance. This determination is based on the ability of these materials to survive impact with the lowest friction of impact energy resulting in damage. In addition laminates with biaxial reinforcement ... |
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| Mechanisms of Strength and Toughness in a Microalloyed, Precipitation Hardened Steel |
APR 89 |
226 pages |
| Authors:
M. E. Natishan; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| The microstructural parameters contributing to the strength and toughness of low carbon, microalloyed, precipitation hardenable steels were identified in two ASTM A710, grade A, 50 mm thick plates in the reaustenitized, quenched and aged condition. Tensile, impact toughness and fracture toughness properties were determined over a full range of test temperatures to characterize the mechanical behavior and the fracture processes in the fracture mode transition temperature region, especially as related ... |
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| Effects of High Rate Shear on the Microstructure and Deformation and Fracture Behavior of Two High Strength Steels |
APR 89 |
171 pages |
| Authors:
E. M. Hackett; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| The shear localization behavior of two high strength stee ls was evaluated at loading rates ranging from quasi-static to impact. The steels evaluated were similar in yield strength, but had different levels of toughness. The steel with superior toughness was direct quenched (DQ). The second steel was quenched and tempered (Q&T). Fatigue precracked Dual Notched Shear (DNS) specimens, loaded in mode II (in-plane shear), were employed. The objectives were to ... |
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| Calibration of Impulse Technique Experimental Set-Up for Determination of Damping Loss Factor |
MAR 89 |
44 pages |
| Authors:
Roger M. Crane; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Composite materials are currently being considered for numerous Naval applications. Among their many advantages, their inherent vibration damping characteristics is becoming a dominant design consideration. To date, however, there are no analytical techniques which have the capability of predicting the damping loss factor of a particular composite system. One is therefore limited to experimental determination of the damping loss factor for composite materials which requires a high degree of accuracy ... |
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| Instrumented Impact Testing of Composite Materials |
JAN 89 |
36 pages |
| Authors:
Roger M. Crane; Thomas D. Juska; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| One material characteristic that is gaining increased importance in composite materials is their impact resistance. The test method has been widely accepted in the aerospace industry for determining a degree of 'toughness' is the instrumented impact test followed by post-impact compression testing. This combination of tests is called compression after impact (CAI) testing. Two aspects that are important to the results are the energy absorbed during the impact test and ... |
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| Estimation of Lower Bound Properties from Material Test Data |
JAN 89 |
28 pages |
| Authors:
M. T. Kirk; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Monte Carlo simulations were performed to determine how the accuracy of lower bound values estimated from experimental data is influenced by sampled size required confidence level, and assumed statistical mode. Population distributions having different degrees of skewness, selected to bracket those expected in actual experimental data, were studied. For nearly every case considered, lower bound estimates calculated using Log-Normal statistics were more accurate than estimates calculated using either Normal or ... |
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| A Hybrid Collocation Technique for Solution of the Finite Body Single Ended Crack Problem |
JAN 89 |
112 pages |
| Authors:
Mark T. Kirk; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| A hybrid experimental/numerical collocation technique was developed for analysis of two dimensional, finite body, single-ended crack problems. Both boundary stress conditions, known a priori, and interior and stress conditions, determined from photoelastic model, were used to specify the loading imposed on the the specimen. It was determined that including the interior stress conditions in the analysis increases the rate of solution convergence. Additionally, the interior stress conditions allowed both the ... |
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| Burner Rig Test of Economizer and Superheater Boiler Tube Alloys |
OCT 88 |
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| Authors:
Louis F. Aprigliano; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
|
| Economizer and superheater boiler tube alloys of 1018 carbon steel, 2-1/4Cr 1Mo steel, and 316, 321, and 347 stainless steels were exposed to burner rig tests at 310 F and 975 F (155 C and 524 C), which respectively are typical economizer and superheater temperatures. The tests were made using MIL-F-16884H Navy distillate fuel with 0.0 and 0.3 ppm vanadium content. This was done to reveal problems that might result ... |
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| X-Ray Photoelectron Spectroscopy Study of Samples in the Y-Ba-Cu-O system |
OCT 88 |
39 pages |
| Authors:
L. F. Aprigliano; B. Friedman; R. J. Stockhausen; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| Superconducting ceramics that have critical temperatures which exceed the boiling point of liquid nitrogen (77 K) have been discovered. Preliminary studies both in the United States and Japan indicate that the superconducting properties of these ceramics can degrade with exposure to water vapor during processing. X ray photoelectron spectroscopy (XPS) is a possible method with which to study this problem. The goal of this research was to determine if there ... |
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| The Effects of Microbial Biofilms on Organotin Release by an Antifouling Paint |
AUG 88 |
20 pages |
| Authors:
James W. Mihm; George I. Leob; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| The effect of microbial films on the release rate and speciation of tributyltin toxin from an organotin paint was determined. Test panels were coated with organotin copolymer ablative antifouling paint. The release rates of the panels were measured before and after biofilms were formed, and after they were mechanically removed. Results show that the bacterial films decreased the release rate but did not degrade the tributyltin. Algal films showed an ... |
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| Fracture behavior Prediction for Rapidly Loaded Surface Cracked Specimens |
AUG 88 |
15 pages |
| Authors:
M. T. Kirk; E. M. Hackett; DAVID TAYLOR RESEARCH CENTER BETHESDA MD SHIP MATERIALS ENGINEERING DEPT
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| The feasibility of predicting the fracture behavior of surface cracks from shallow cracked bend specimens was investigated. The material studied was a high strength steel stress relief embrittled to various levels of Charpy-V notch impact toughness. Material toughness was quantified in terms of the J-integral at total specimen failure (JCRIT), using both deeply notched and shallow notched bendbars (SE(B)) dynamically loaded in a drop tower impact testing machine. These data ... |
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