| Development of Toughened and Multifunctional Nanocomposites for Ship Structures |
06 Jul 2012 |
34 pages |
| Authors:
C T Sun; PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
|
 | This report consists of two parts. The objective of the first part of the research was to use a sol-gel in-situ produced silica nanoparticle-modified epoxy to manufacture fiber composites in order to enhance the mechanical properties of fiber composites. Vacuum assisted resin transfer molding (VARTM) process was used to fabricate unidirectional E-glass fiber reinforced silica/epoxy nanocomposites. Off-axis composite specimens with and without silica nanoparticles were tested to compare the compressive ... |
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| Brick Paving Systems in Expeditionary Environments: Field Testing |
Jul 2012 |
101 pages |
| Authors:
Haley P Bell; Quint Mason; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| Personnel of the U.S. Army Engineer Research and Development Center were tasked by Headquarters, Air Force Civil Engineer Support Agency, to determine the feasibility of using face bricks as an alternative to concrete or asphalt paving for low-volume roads and military aircraft parking aprons in expeditionary environments. Because paving materials and equipment can be scarce in these areas, the use of recycled bricks from existing infrastructure might provide a local ... |
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| The Compressive Failure of Aluminum Nitride Considered as a Model Advanced Ceramic |
Jun 2012 |
27 pages |
| Authors:
Guangli Hu; K T Ramesh; Buyang Cao; J W McCauley; JOHNS HOPKINS UNIV BALTIMORE MD DEPT OF MECHANICAL ENGINEERING
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| Uniaxial quasi-static compression, uniaxial dynamic compression and confined dynamic compression experiments were performed to characterize the failure of Aluminum Nitride (AlN) using a servo hydraulic machine and a modified Kolsky bar set-up respectively. High-speed digital cameras are used to visualize the failure processes. A summary of the available experimental results, including that in the literature, shows that the compressive strength of the AlN is sensitive to strain rate in the ... |
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| An Experimental Study in the Mechanical Response of Polymer Modified Geopolymers |
Apr 2012 |
35 pages |
| Authors:
Benjamin Valera; ROCHESTER INST OF TECH NY Dept of Mechanical Engineering
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| The objective of this project was to evaluate the effect of low molecular weight of Poly Ethylene Glycol (PEG), Carboxy Methyl Cellulose (CMC) on metakaolin and F type fly ash sodium based geopolymers in their mechanical response. It was found that adding 22.5% per weight of a Carboxyl Methyl Cellulose solution to metakaolin geopolymers over a mesh of cheesecloth modifies the elastic modulus producing a plate with enhanced flexibility. This ... |
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| Laboratory Characterization of Talley Brick |
Aug 2011 |
70 pages |
| Authors:
Hannah B Beatty; Steven S Graham; Erin M Williams; Paul A Reed; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| Personnel of the Geotechnical and Structures Laboratory, U.S. Army Engineer Research and Development Center conducted a laboratory investigation to characterize the strength and constitutive property behavior of Talley brick. A total of 24 mechanical property tests were successfully completed, i.e., three hydrostatic compression tests, three unconfined compression (UC) tests, 12 triaxial compression (TXC) tests, two uniaxial strain (UX) tests, two uniaxial-strain-load/constant-volumetric-strain in-load (UX/CV) tests, and two direct-pull (DP) tests. In ... |
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| Geopolymer Porous Nanoceramics for Structural, for Smart and Thermal Shock Resistant Applications |
02 FEB 2011 |
12 pages |
| Authors:
Waltraud M. Kriven; ILLINOIS UNIV AT URBANA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| We have continued our work to understand and elucidate the microstructure of geopolymers and geopolymer composites, as fabricated and upon conversion to ceramics with heating. The microstructure consisted of nanoporous, nanoparticulate precipitates, and contains roughly approximately 40% nanoporosity of average diameter 6.8 nm in the case of K-based geopolymer. The room temperature compressive strengths were systematically investigated as a function of Group I charge balancing cations (Na, K, and Cs ... |
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| Geopolymer Porous Nanoceramics for Structural Smart and Thermal Shock Resistant Applications |
02 FEB 2011 |
11 pages |
| Authors:
Waltraud M. Kriven; ILLINOIS UNIV AT URBANA-CHAMPAIGN
|
| We have continued our work to understand and elucidate the microstructure of geopolymers and geopolymer composites, as fabricated and upon conversion to ceramics with heating. The microstucture consisted of nanoporous, nanparticular precipitates and contains 40% nanoporosity of average diamter 6.8nm in the case of K-based geopolymer. The room temperature compressive strengths were systematically investigated as a function of Group I charge balancing cations (Na, K and Cs and mixtures of ... |
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| NbTiSiMo-X Alloys-Composition, Microstructure Refinement and Properties (Preprint) |
Mar-2009 |
15 pages |
| Authors:
C Woodward; Y-W Kim; S Menon; UES INC DAYTON OH
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| Advanced NbTiSi-X alloys have demonstrated very high RT strength levels (compressive yield strength approaching 1,800 MPa) and excellent high-temperature strength retention (approx. 1,200 MPa at 1,000 degrees C and over 500 MPa at 1,200 degrees C). Unfortunately, these alloys have an inhomogeneous size and spatial distribution of silicides, low fracture strength under tension (300 MPa) at all temperatures, and low oxidation resistance. The high volume fraction and non-uniform size distribution ... |
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| Friction on Crack Surfaces During Compression of Explosives - A Possible Ignition Source for Unplanned Explosions Due to Accidental Deformations |
Dec-2008 |
8 pages |
| Authors:
Donald A Wiegand; Brett Redingius; Kevin Ellis; Claire Leppard; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER PICATINNY ARSENAL NJ
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| The mechanical properties of composite plastic bonded explosives have been investigated as a function of confining pressure. The results indicate different failure processes in two pressure ranges, a low pressure range between about 0.1 to 7.0 MPa which is considered in this paper and a higher pressure range. In the low pressure range crack processes are important in failure. The pressure dependence of the compressive strength in the low pressure ... |
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| Dynamic Failure Processes Under Confining Stress in AlON, a Transparent Polycrystalline Ceramic |
Dec-2008 |
9 pages |
| Authors:
James W McCauley; B Paliwal; K T Ramesh; Mingwei Chen; SANDIA NATIONAL LABS ALBUQUERQUE NM
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| An experimental technique is developed to impose a planar lateral confinement in a prismatic specimen (with rectangular cross-section); the setup enabled a controlled and homogeneous stress state with high lateral compressive stresses. A transparent polycrystalline aluminum oxynitride (AlON) specimen was used for the study. The statically pre-compressed specimen was then subjected to axial dynamic compressive loading using a modified compression Kolsky bar setup. Experimental design was performed using 3D computational ... |
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| Rapid Chemical Stabilization of Soft Clay Soils |
Oct-2008 |
10 pages |
| Authors:
Susan D Rafalko; Thomas L Brandon; George M Filz; James K Mitchell; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING
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| Since World War II, the military has sought methods for rapid stabilization of weak soils for support of its missions worldwide. Over the past 60 years, cement and lime have been the most effective stabilizers for road and airfield applications, although many nontraditional stabilizers also have been developed and used. The most effective stabilizer to increase the strength of two soft clay soils within 72 h for contingency airfields to ... |
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| Life Prediction of High Temperature Polymer Matrix Composites for Aircraft Engine and Airframe Applications |
Sep-2008 |
39 pages |
| Authors:
Hongbing Lu; Samit Roy; ALABAMA UNIV TUSCALOOSA DEPT OF AEROSPACE ENGINEERING AND MECHANICS
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| Dynamic experiments were conducted to evaluate the effects of oxidation on the mechanical properties of both 5250-4 resin and its composite under high strain rates. A long split Hopkinson pressure bar was used in experiments. For the resin oxidized at 245 deg C for 1500 hrs its mechanical properties, such as Young's modulus and compressive strength, show only slight reduction at high strain rates. For composites oxidized at 195 deg ... |
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| Quality Assurance for Rapid Airfield Construction |
MAY 2008 |
123 pages |
| Authors:
Reed B. Freeman; Travis A. Mann; L. W. Mason; Chad A. Gartrell; Vernon M. Moore; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
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| This investigation was conducted to formalize a quality assurance (QA) process for rapid airfield construction. The specific aspects of QA that were addressed included compaction operations and the assessment of strength for both soil and stabilized soil layers. The QA for compaction relies on the construction of a test section for determining optimum number of compaction coverages and target soil properties. The essential pieces of equipment for the compaction QA ... |
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| Light-Weight Materials Selection for High-Speed Naval Craft |
Jun-2007 |
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| Authors:
Joseph B Torrez; MASSACHUSETTS INST OF TECH CAMBRIDGE
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 | A decision analysis study was conducted on the process of materials selection for high-speed naval craft using the Modified Digital Logic (MDL) method. The purpose is to show how this method along with Ashby's material selection process can be integrated to provide a comprehensive tool designed specifically for light-weight material optimization. Using Ashby's Material Selection Charts and the MDL method, a step by step material selection process is outlined. Furthermore, ... |
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| A Review of the Fabrication and Properties of Vapor-Grown Carbon Nanofiber/Polymer Composites (Preprint) |
MAR 2006 |
36 pages |
| Authors:
Gary G. Tibbetts; Max L. Lake; Karla L. Strong; Brian P. Rice; APPLIED SCIENCES INC CEDARVILLE OH
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| Several varieties of vapor-grown carbon nanofibers with diameters under 200 nm and conically shaped grapheme planes canted with respect to the longitudinal fiber axis are available. Because of the strong interfiber bonding, compounding these fibers with polymeric resins demands some care. Therefore, fabrication of nanofiber composites has led to variable and occasionally disappointing electrical conductivity and tensile strength. In the following paper, we review the published data for vapor-grown carbon ... |
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| Development of Advanced Oxide Dispersion Strengthened Tungsten Heavy Alloy for Penetrator Application |
30 SEP 2005 |
47 pages |
| Authors:
Soon H. Hong; Ho J. Ryu; Seung I. Cha; Hee Y. Kim; Kyung T. Kim; Kyong H. Lee; Chan B. Mo; KOREA ADVANCED INST OF SCIENCE AND TECHNOLOGY DAEJEON (KOREA)
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| The effects of fabrication process parameters, including conditions for powder preparation, sintering, cyclic heat-treatment, swaging, and annealing processes, on microstructures and static/dynamic mechanical properties of ODS tungsten heavy alloys were investigated. The composition of ODS tungsten heavy alloys was designed as 94W-4.56Ni-1.14Co-0.3Y2O3 which show the highest strength at similar microstructural parameters based on the analysis of microstructures and mechanical properties. The two-stage sintered ODS tungsten heavy alloy showed finer tungsten ... |
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| Dynamic Compressive Responses and Flow Behavior of Damaged Ceramics Under High Confinement |
30 JUN 2005 |
10 pages |
| Authors:
Weinong W. Chen; ARIZONA UNIV TUCSON
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| We developed a novel dynamic loading/reloading experimental technique modified from a split Hopkinson pressure bar (SHPB) to determine the dynamic properties and to record the damage/failure modes in the ceramic specimen, in which a ceramic specimen was loaded by two consecutive stress pulses. The first pulse determines the dynamic response of the intact ceramic material and then crushes the specimen to a desired damage level. The second pulse then determines ... |
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| France-Australia Technical Arrangement TA 1/99 - Work Package 2: Ab Initio Estimation of Composite Properties |
APR 2005 |
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| Authors:
Paul J. Callus; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) PLATFORM SCIENCES LAB
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| Substantial savings could be made in the cost of airworthiness certification of composite aircraft structure if material properties could be predicted solely on the basis of the properties of the constituent fibres and resin. The feasibility of this approach was tested by surveying the literature on the prediction of compression strength. The literature is extensive and indicates that the compression failure process is well understood. The critical factors controlling compression ... |
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| Assessment of Foreign Bridge Standards and Techniques |
SEP 2004 |
131 pages |
| Authors:
Anthony J. Lamanna; Mustafa Lok; Gerardo I. Velazquez; James C. Ray; Terry R. Stanton; TULANE UNIV NEW ORLEANS LA DEPT OF CIVIL ENGINEERING
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| Turkish bridge design standards were studied and compared with American design specifications, with attention focused on the live load. The major difference between the two standards was that the live load in Turkish standards is given in tonnes, whereas, in the American Association of State Highway and Transportation Officials Standard Specifications for Highway Bridges (AASHTO 1996) it is in tons. Therefore, HS20 in Turkish standards is 10 percent heavier than ... |
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| Strength Enhancement and Application Development of Carbon Foam for Thermal Protection Systems |
SEP 2004 |
6 pages |
| Authors:
Christopher Duston; Steve Seghi; Roland Watts; CERAMIC COMPOSITES INC MILLERSVILLE MD
|
| Carbon foam is recognized as having great potential as a component within hybrid (rainbow) Thermal Protection Systems for low angle re-entry vehicles. In this concept, the carbon foam supports a ceramic matrix composite surface by providing selectable insulating or thermally conductive dual-use properties. An initial barrier to implementation was the inherent weakness and friability of the carbon foams. Under a MDA funded SBIR program, Ceramic Composites Inc. has demonstrated the ... |
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| A Study on the Transient Response of a Stepped Column Subjected to an Impact Load |
JUN 2004 |
61 pages |
| Authors:
Tae-hak Park; Young S. Shin; NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF MECHANICAL AND ASTRONAUTICAL ENGINEERING
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| This report presents the results of studies on the stiffness variation effects to the structures such as ship, missile and airplane subjected to an axial or a vertical impact load. The theoretical studies were carried out for a simply supported beam under an axial compressive load and a cantilever beam under a vertical load. A transient analyses for beams and cylindrical shells were performed, and the results were evaluated. It ... |
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| Evaluation of Materials for Rapid Runway Repair |
2004 |
6 pages |
| Authors:
Michael Riley; CERATECH INC BALTIMORE MD
|
| While the goals of this effort are to improve the strength and thermal resistance characteristics of PaveMend products, ultimate cost will also be kept as a determining factor. The metal oxides currently used in PaveMend products are magnesia/alumina based, but are irregular shaped ground particulates. To add stiffness and additional compressive strength to the product, we will investigate the role of chopped ceramic fibers as low weight additives to the ... |
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| Ar Ion Beam Irradiation Effects on Magnetostriction of Tb-Fe Thin Film |
17 JUN 2003 |
7 pages |
| Authors:
M. Takeuchi; Y. Matsumura; H. Uchida; T. Kuji; TOKAI UNIV HIRATSUKA (JAPAN)
|
| TbFe2 film prepared by a flash evaporation system onto Si(100) or polyamide substrate have been irradiated with different Ar ion doses at zero, 1. 3x10-17 and 2.7x10-17 ions/cm2 and at 10 kV. Magnetostrictive properties of TbFe2 film with disordered structure, saturated magnetostriction and magnetostrictive susceptibility, improved by Ar ion beam irradiation due to increasing of in-plane compressive stress. |
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| Compression Behavior of High Performance Polymeric Fibers |
JUN 2003 |
23 pages |
| Authors:
Satish Kumar; Byung G. Min; Steekumar T. Veedu; Tao Liu; Tetsuya Uchida; GEORGIA INST OF TECH ATLANTA SCHOOL OFTEXTILE AND FIBER ENGINEERING
|
| Hydrogen bonding has proven to be effective in improving the compressive strength of rigid-rod polymeric fibers without resulting in a decrease in tensile strength while covalent crosslinking results in brittle fibers. Tensile strength of the PBO/SWNT fiber containing 10 wt% SWNT is over 50% higher than that of the control PBO fibers containing no SWNT. An optically homogeneous solution/dispersion of single wall carbon nanotubes (SWNTs) in oleum has been used ... |
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| Experimental Data, Numerical Fit, and Fatigue Life Calculations Relating to the Bauschinger Effect in High-Strength Armament Steels |
APR 2003 |
19 pages |
| Authors:
Edward Troiano; Anthony P. Parker; John Underwood; Charles Mossey; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
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| The uniaxial Bauschinger effect has been evaluated in several high strength steels being considered for armament use. Tests were conducted at plastic strains up to 3.5%. Results of testing show a progressive decrease in Bauschinger effect up to plastic strains of approximately 1% (for all materials investigated), after which there is little further decrease. |
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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
|
| 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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| Sustaining an Aging Aircraft Fleet with Practical Life Enhancement Methods |
FEB 2003 |
12 pages |
| Authors:
Len Reid; FATIGUE TECHNOLOGY INC SEATTLE WA
|
| Extension of aircraft beyond their original design service life or operation in expanded or different roles pose challenges in continuing to operate these aircraft economically or safely. Management of the fleet generally entails increased structural inspection and maintenance, repair of inevitable fatigue damage or possible structural replacement. In a large number of cases structural elements become life limiting or require major rework due to fatigue cracks and damage originating at ... |
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| Microstructure and Dynamic Behavior Correlation in Two-Phase TiB2+Al2O3 Ceramic |
OCT 2002 |
104 pages |
| Authors:
Naresh N. Thadhani; Min Zhou; GEORGIA INST OF TECH ATLANTA SCHOOL OFMATERIALS SCIENCE AND ENGINEERING
|
| The high-strain-rate deformation and damage response of four types of microstructurally-biased two-phase (nominally 30:70) TiB2+Al2O3 ceramics, produced by SHS or mechanical milling techniques, have been investigated in this work. The microstructural-bias includes differences in phase (grain) size and phase distribution, such that in one case a continuous (interconnected) TiB2 network surrounds the Al2O3 phase (qualitatively termed TA'), and in the other case the TiB2 and Al2O3 phases are interdispersed and ... |
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| PaveMend (trademark) as a Solution for Rapid Runway Repair |
JUL 2002 |
11 pages |
| Authors:
Mark Anderson; Michael A. Riley; APPLIED RESEARCH ASSOCIATES INC PANAMA CITY FL
|
| The paper first gives definition and historical perspective to the problem of Rapid Runway Repair (RPR). The differences in Cold War and post-Cold War RRR needs are also discussed. CeraTech, Inc.'s PaveMend(TradeMark) is presented as a good solution for post-Cold War RRR needs, which are speed of the repair and durability of the repair. The homogeneous nature of PaveMend(TradeMark) is illustrated by a photomicrograph, and the ability of PaveMend(TradeMark) to ... |
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| Self-Assembly of a Modular Polypeptide Based on Blocks of Silk-Mimetic and Elastin-Mimetic Sequences |
APR 2002 |
7 pages |
| Authors:
Chrystelle S. Cazalis; Vincent P. Conticello; EMORY UNIV ATLANTA GA DEPT OF CHEMISTRY
|
| Spider dragline silk fiber displays a unique and technologically significant combination of high tensile and compressive strength. The structural origin of these properties arises from the alternating sequence of crystalline alanine-rich domains and amorphous glycine-rich domains, which undergo microscopic phase separation in the silk fiber. We previously reported the synthesis and the self-assembly of a novel polypeptide 1, which emulates the modular structure of crystalline and amorphous elastomeric domains in ... |
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| Orthotropic Mechanical Properties of Uncoated and Ceramic-Coated Uniaxially-Compressed Carbon Cellular Porous Materials |
15 AUG 2001 |
|
| Authors:
David Barland; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE WEST
|
| Porous cellular foams of moderate to high porosity (55%-95%) were investigated to determine orthotropic strength moduli and mechanical response. Uncoated porous samples consisted of reticulated vitreous carbon (RVC) rigidized by pyrolysis of flexible, open-pore organic precursor foams. The organic precursor's reference surface pore density was 100 pores-per-inch (ppi) before uniaxial compression. After compression, substrates contained 6% to 33% solid fraction, which corresponded in the thru-thickness direction to 200 ppi to ... |
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| The Micromechanisms of Flow and Fracture of Ice |
JUL 2001 |
21 pages |
| Authors:
Ian Baker; THAYER SCHOOL OF ENGINEERING HANOVER NH
|
| The overall goals of this work were to relate the microstructure, including the defect structure and impurity content and location, to the mechanical and physical properties of ice. Research focused on determining the structure and microstructural location of impurities in natural ice using a scanning electron microscope equipped with a cold stage and x-ray microanalysis. Thus, for the first time, the microstructure and microchemistry of pond and river ice was ... |
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| The Effect of Loading Parameters on Fatigue of Composite Laminates: Part V |
JUN 2001 |
58 pages |
| Authors:
H. T. Hahn; S. W. Choi; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| This report is the fifth in a series of reports on the damage growth of notched and visible impact-damaged AS4/3501-6 graphite/epoxy quasi-isotropic laminates under long-term mechanical fatigue loading. The effects of load type, load level, load sequence, and spectrum modification are evaluated in this study. X-ray radiography is taken of the test specimens to monitor the fatigue damage, which are in the form of splitting and delamination around the center ... |
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| Material Qualification and Equivalency for Polymer Matrix Composite Material Systems |
APR 2001 |
119 pages |
| Authors:
John S. Tomblin; Yeow C. Ng; K. S. Raju; NATIONAL INST FOR AVIATION RESEARCH WICHITA KS
|
| This document presents a qualification plan that will provide the detailed background information and engineering practices to help ensure the control of repeatable base material properties and processes, which are applied to both primary and secondary structures for aircraft products using composite materials. This qualification plan includes recommendations for the original qualification as well as procedures to statistically establish equivalence to the original data set. The plan describes in detail ... |
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| Impact Damage Characterization and Damage Tolerance of Composite Sandwich Airframe Structures |
JAN 2001 |
181 pages |
| Authors:
John S. Tomblin; K. S. Raju; J. Liew; B. L. Smith; WICHITA STATE UNIV KS
|
| The use of composite sandwich construction is rapidly increasing in current and future airframe designs. Typically, these sandwich constructions use thin gage composite facesheets (0.020" to 0.045") which are co-cured to honeycomb and foam cores. Due to the nature of these structures, damage tolerance is more complex than conventional laminated structures. Besides typical damage concerns such as through penetration and delamination, additional modes including core crushing and facesheet debonding must ... |
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| Penetrator Resistance and Target Damage due to Multiple Impacts Upon Granite and Concrete: |
MAY 2000 |
99 pages |
| Authors:
Arun Shukla; Martin Sadd; RHODE ISLAND UNIV KINGSTON DEPT OF MECHANICAL ENGINEERING AND APPLIED MECHANICS
|
| The objectives of this work were to develop first principle-based understanding of multiple impact, penetration, and damage accumulation in granite and concrete, and to develop a predictive model for multiple impact penetration. The extensive use of granite arid concrete in military applications provides motivation for this work. In order to understand the penetration process of granite and concrete dynamic and static material properties were determined ... |
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| Engineering and Design. Roller-Compacted Concrete |
15 JAN 2000 |
77 pages |
| Authors:
CORPS OF ENGINEERS WASHINGTON DC
|
| The purpose of this manual is to provide information and guidance on the use of roller-compacted concrete (RCC) in dams and other civil works structures. Elements discussed include investigation and selection of materials, mixture proportioning, material properties, design and construction considerations, construction methods and equipment, Government Quality Assurance/Contractor Quality Control, and performance. This manual is intended to serve as a companion to Engineer Manual (EM) 1110-2-2000, "Standard Practice for Concrete ... |
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| Fundamental Investigations of Plasticity in High Strength Nanostructured Aluminum Alloys |
2000 |
8 pages |
| Authors:
Rajiv S. Mishra; MISSOURI UNIV-ROLLA DEPT OF METALLURGICAL ENGINEERING
|
| Cryomilled aluminum alloys are being developed for aerospace applications. These high-strength aluminum alloys are currently targeted for low-temperature rocket applications. This research focused on the fundamental strengthening mechanisms in these alloys. The primary sources of strengthening in cryomilled aluminum alloys are dispersion of nanocrystalline particles and ultrafine grain size that form during the cryomilling stage. Optimized thermo- mechanical processing of cryomilled powder results in an ultrafine grain size material with ... |
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| Investigation of the Compressive Material Properties of PZT and PMN |
01 DEC 1999 |
21 pages |
| Authors:
Lynn M. Ewart; Elizabeth A. McLaughlin; Kim D. Gittings; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
|
| In U.S. Navy sonar transducers, me electroactive ceramics are subject to mechanical compressive stresses. However, there has been scant research to examine the mechanical effects of compressive loads on electroactive ceramics. The research reported herein measured material properties (compressive strength, Young's modulus, and Poisson's ratio) and studied the behavior in compression and under short circuit conditions of five commercially available lead zirconate titanate (PZT) and lead magnesium ... |
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| Fatigue Damage Mechanisms of Advanced Hybrid Titanium Composite Laminates |
NOV 1999 |
133 pages |
| Authors:
Donald W. Rhymer; GEORGIA INST OF TECH ATLANTA SCHOOL OFMECHANICAL ENGINEERING
|
| The objective of this thesis is to compare the mechanical response of this advanced Hybrid Titanium Composite Laminates (HTCL) to the first generation material. Specifically, the effect of a stronger bondline at the titanium/ Polymer Matrix Composites (PMC) interface in constant amplitude fatigue will be investigated, particularly in the event that titanium ply cracking induces the delamination. Therefore, the focus of this research is to closely monitor ... |
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| Analysis of Russian "Vertex" High-Strength Glass Fiber |
SEP 1999 |
51 pages |
| Authors:
William A. Spurgeon; Elias J. Rigas; Matthew S. Burkins; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| This report presents the results of mechanical and ballistic tests required in MIL-PRF-46l9?A (U.S. Department of the Army, "A Laminate, High Strength Glass Fiber Reinforced Polyester Resin," U.S. Army Research Laboratory, Aberdeen Proving Ground, MD, 16 April 1997) on Russian Vertex high-strength glass that is supposed to be equivalent to domestic S-2 glass. The results of tensile tests of 250-yield yarns of both types of fibers were very similar, with ... |
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| Dynamic Behavior of Brittle Materials |
JUL 1999 |
8 pages |
| Authors:
L. B. Freund; BROWN UNIV PROVIDENCE RI
|
| The goal of the program was to characterize and quantify physical processes involved in failure of brittle materials under impact loading conditions, and to synthesize results to identify properties which determine the effectiveness of a system (material and configuration) in resisting failure. This was accomplished by developing new methodologies which integrate concepts in mechanics and materials science. Among the accomplishments are: determining the pressure-shear response of alumina powders and of ... |
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| Dynamic Strength Enhancement of Conventional Concrete |
30 JUN 1999 |
23 pages |
| Authors:
H. D. Kang; Y. S. Roh; K. J. Willam; Y. Xi; COLORADO UNIV AT BOULDER DEPT OF CIVIL ENVIRONMENTAL AND ARCHITECTURAL ENGINEERING
|
| In order to investigate the performance of conventional concrete at different loading rates, experimental results of strength enhancement were obtained under tension and compression tested under different loading speeds. G- mix specimens prepared at the Tyndall Air Force Base were used to determine the range of loading rates of the servo-hydraulic equipment at hand and to obtain experimental results with a series of indirect tension and uniaxial compression tests. For ... |
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| A Novel Manufacturing Processing Route for Forming High-Density Ceramic Armor Materials: Phase II- SBIR |
APR 1999 |
104 pages |
| Authors:
Rams V. Raman; CERACON INC SACRAMENTO CA
|
| The feasibility of a combustion synthesis/Ceracon forging (CS/CF) fabrication process for low-cost high-quality ceramic armor is demonstrated. CS of titanium (Ti) and carbon (C) forming titanium carbide (TiC) was followed by a quasi-isostatic pressurization and densification to produce tiles with 95% + densities with sizes of up to 15 cm x 15 cm x 2.5 Cm. Several tiles were fabricated and delivered to the U.S. Army Research Laboratory (ARL) for ... |
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| Discrete Fiber Reinforcement of Sands for Expedient Road Construction |
MAR 1999 |
107 pages |
| Authors:
Jeb S. Tingle; Steve L. Webster; Rosa L. Santoni; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS GEOTECHNICAL LAB
|
| This report describes laboratory and field experiments conducted using discrete synthetic fibers to stabilize sands for expedient road construction. Unconfined compression tests were conducted as an index of material performance to identify the effects of fiber type, length, content, denier, and sand type on load-bearing capacity. Field sections consisting of 8- in. fiber-stabilized layers over a sand subgrade (SP) were constructed and trafficked to validate the laboratory results under actual ... |
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| Studies of Fracture Processes in Cement-Based Materials under Compression with Microtomography and Computer Vision |
14 FEB 1999 |
10 pages |
| Authors:
Eric N. Landis; Surendra P. Shah; MAINE UNIV AT ORONO DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING
|
| The primary objective of this research program was to provide experimental data to feed into the extensive modeling work of the AFOSR Shock Physics program. Two advanced complimentary experimental techniques were used: x-ray microtomography (XMT) and digital image correlation (DIC) . The former is a three dimensional technique that is restricted to small specimens under static loading, while the latter is a surface-only technique that can be applied in a ... |
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| The Interaction of Kinetic Energy Penetrators With Geomaterials and Concrete |
JAN 1999 |
72 pages |
| Authors:
C. A. Ross; M. J. Schmidt; N. D. Cristescu; O. Cazacu; FLORIDA UNIV SHALIMAR GRADUATE ENGINEERING AND RESEARCH CENTER
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| A large diameter split Hopkinson pressure bar (SHPB) was used to generate dynamic shear strength and confined/unconfined compressive data for mortar. In addition quasistatic shear and compressive strength data were generated for the same mortar. The new shear specimen was modeled using finite element analysis to verify its validity. Strain rate sensitivity of the shear response of mortar is very similar to that of the tension and compression data. A ... |
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| Reactive Powder Concrete for Producing Sewer, Culvert, and Pressure Pipes |
AUG 1998 |
88 pages |
| Authors:
Roy L. Campbell; Edward F. O'Neil; William M. Dowd; Christophe E. Dauriac; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
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| This report documents research to develop and demonstrate the technical and economic viability of reactive powder concrete (RPC) a very high strength, high performance concrete material for producing precast sewer/culvert and pressure pipes with the ultimate program goals of gaining construction industry acceptance and implementing wide scale commercial fabrication of these products. By optimizing the design of the precast RPC pipes, it was projected that ... |
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| Dynamic Increase Factors for Concrete |
Aug-1998 |
18 pages |
| Authors:
L J Malvar; John E Crawford; NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA
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| For reinforced concrete structures subjected to blast effects, response at very high strain rates (up to 1000 s(-1)) is often sought. At these high strain rates, the apparent strength of concrete can increase significantly. The dynamic increase factor (DIF), i.e. the ratio of the dynamic to static strength, is normally reported as function of strain rate. For concrete, the DIF can be more than 2 in compression, and more than ... |
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| Deformation Behavior of 93W-5Ni-2Fe at Different Rates of Compression Loading and Temperatures |
JUL 1998 |
42 pages |
| Authors:
Tusit Weerasooriya; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Low (0.0001 to 0.1 per s) and high (9,000 per s average) strain-rate uniaxial compression experiments were performed on a tungsten heavy alloy (WHA) at room temperature; high-rate experiments were conducted using the Compression Split-Hopkinson Bar apparatus. In addition, high-temperature tests at 423, 573, and 732 K were conducted at 0.1 per s strain-rate. The deformation and failure behaviors of this alloy under compression loading ... |
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COMPRESSIVE STRENGTH
