| A Fully Contained Resin Infusion Process for Fiber-Reinforced Polymer Composite Fabrication and Repair |
Jan 2013 |
22 pages |
| Authors:
Jr Holmes Larry R; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
 | In laboratory or manufacturing conditions, the Vacuum-Assisted Resin Transfer Molding (VARTM) process is applicable for fiber-reinforced polymer (FRP) composite fabrication and repair. However, VARTM in not optimal for in-field processing or repair due to the precision required in measuring and mixing, and the need to remain contaminate free. Current repair constraints require damaged FRP composites to be returned to repair depots resulting in excessive cost. One solution to this costly ... |
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| Polymer/Carbon Nanotube Networks for Smart, Self-Repairing and Light-Weighted Nanocomposites |
05 Nov 2012 |
37 pages |
| Authors:
J Zekonyte; SOUTHAMPTON UNIV (UNITED KINGDOM)
|
| The aim of the project was develop smart, strong, and light-weight polymer/carbon nanotube (CNT) composites which will sense tribologically induced damages and self-heal by inhibiting such degradation mechanisms, so preventing failure of the composite. The main focus was on the preparation of new multifunctional coatings and thin films. By incorporation of CNTs we expected to create films with increased surface hardness and resistance to failure. We intended to prepare composites ... |
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| Mechanical Testing of 3D Fabric Composites and Their Matrix Material SC-15 |
Nov 2012 |
32 pages |
| Authors:
Brian Justusson; Jian Yu; Albert Chen; Chian-Fong Yen; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The U.S. Army is actively investigating advanced light-weight structural materials for protective applications in combat vehicles. One such class of materials is Fiber Reinforced Polymer Composites (FRPC). FRPC are a class of materials that consist of a polymeric matrix that is reinforced through the inclusion of long fibers that are bundled together in a structure known as a fiber tow. Traditional FRPC structures generally contain stacks of individual layered fabrics ... |
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| Edge-Selectively Functionalized Graphene-Like Platelets as a Co-curing Agent and a Nanoscale Additive to Epoxy Resin |
12 Aug 2012 |
16 pages |
| Authors:
Jong-Beom Baek; ULSAN NATIONAL INSTITUTE OF SCIENCE AND TECHNOLOGY (KOREA SOUTH)
|
| A newly developed method for the edge-selective functionalization of pristine graphite with 4-aminobenzoic acid was applied for the synthesis of 4-aminobenzoyl-functionalized graphite (AB-graphite) through a direct Friedel-Crafts acylation in a polyphosphoric acid (PPA)/phosphorous pentoxide medium (P2O5). The AB moiety at the edge of the AB-graphite played the role of a molecular wedge to exfoliate the AB-graphite into individual graphene and graphene-like platelets upon dispersion in polar solvents. These were used ... |
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| Novel Metal-Matrix Composites With Integrally-Bound Nanoscale Carbon |
Jun 2012 |
5 pages |
| Authors:
David R Forrest; Iwona Jasiuk; Lloyd Brown; Peter Joyce; Azzam Mansour; Lourdes Salamanca-Riba; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| We characterized the chemical, thermophysical, and mechanical properties of nanomaterials with up to 5 wt% nanocarbon (aka covetics) in aluminum and copper metals. The nanocarbon is detectable by EDS and XPS but not by analytical methods such as LECO and GDMS. Nanocarbon raises the melting point and significantly alters surface tension, and thus porosity, during solidification. Open questions remain about the observation of higher density than would be predicted by ... |
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| A New Type of Carbon Nanostructure Formed Within a Metal-Matrix |
Jun 2012 |
5 pages |
| Authors:
Lourdes Salamanca-Riba; Romaine Isaacs; Azzam N Mansour; Adam Hall; David R Forrest; Melburne C LeMieux; Jason Shugart; MARYLAND UNIV COLLEGE PARK
|
| Recent advances in nanomanufacturing have made it possible for large amounts ( 6 wt.%) of carbon to be incorporated as nanoscale carbon during a reaction process in molten aluminum, copper, silver, and other metals. These materials developed by Third Millennium Metals, LLC are called covetics. The carbon is highly stable despite its form not being predicted in phase diagrams, and remains dispersed after remelting and resolidification. The carbon incorporates into ... |
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| Cyanate Ester Graphene Composites |
29 Mar 2012 |
20 pages |
| Authors:
Josiah T Reams; Andrew Guenthner; Kevin R Lamison; Joseph M Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIR/SPACE AND MISSILE PROPULSION DIV/PROPUL MATERIALS APPLICATIONS BR
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| Graphene oxide produced by chemical oxidation formed stable dispersions in LECy cyanate ester matrix and edge functionalized graphite does not. High shear mixing followed by sonication was the best method for graphene oxide dispersion in LECy. Addition of 1 wt% edge-functionalized graphite of LECy did not increase storage modulus but addition of 1 and 2 wt% GO increased storage modulus below the Tg. Diffusion of water in LECy 1 wt% ... |
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| Electromagnetic Interference Behavior of Multiwall Carbon Nanotubes and Carbon Nanofibers Composites Under Fatigue |
Mar 2012 |
151 pages |
| Authors:
Peter A Hunt; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT
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| The United States military is researching the use of nanocomposite materials for structural applications on space vehicle systems. To reduce vehicle weight and mitigate the electromagnetic interference (EMI) brought on by the harsh space environment, today's space vehicles are made of composites coated with expensive conductive materials. Research on composites made of carbon nanotubes (CNT) and carbon nanofibers (CNF) has shown better EMI shielding performance with these materials compared to ... |
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| Understanding Natural Silks and Their Integration into Composites |
01 Feb 2012 |
16 pages |
| Authors:
Fritz Vollrath; OXFORD UNIV (UNITED KINGDOM) DEPT OF ZOOLOGY
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| The extreme toughness of many spider silks depends (i) on the folding of the component proteins as much as (ii) on the hierarchical structures of the multi-protein threads. The spider's complex spinning process plays a major role in the folding and formation of the hierarchy of the silk threads. This is a process that is largely devoted to the controlled extraction of water. Our research project offered, firstly, an important ... |
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| Design of Novel Flame Retardant Materials that Operate through Synergistic Mechanisms |
20 Jan 2012 |
15 pages |
| Authors:
Ramaswamy Nagarajan; Jayant Kumar; MASSACHUSETTS UNIV LOWELL
|
| To understand the influence of structure of polyphenol on the flame retardant characteristics, phenols containing different types of substituents were polymerized and characterized. The nature and position of the substituent on the phenol was controlled to facilitate the coupling of through specific positions to yield polyphenols with enhanced stability and/or flame retardant characteristics. In addition, the role of temperature in minimizing side reactions and formation of low molecular weight oligomers ... |
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| Polymer Composite Using Aligned Carbon Nanotubes for Efficient Heat Transfer |
17 Jan 2012 |
14 pages |
| Authors:
James Fillerup; Mauricio Terrones; INSTITUTO POTOSINO DE INVESTIGACION CIENTIFICA Y TECNOLOGICA SAN LUIS POTOSI (MEXICO)
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| The project objectives are to fabricate novel composites with polymers and arrays of aligned carbon nanotubes for developing enhanced heat transfer devices. Since carbon nanotubes could exhibit extremely high thermal conductivity, aligned nanotubes embedded in polymeric matrices may be a way to generate materials that are able to remove heat, especially in radars, electronic components, and energy and power transformers. This work was focused on the production of aligned nanotube ... |
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| Study of the Progressive Failure of Composites under Axial Loading with Varying Strain Rates |
Dec 2011 |
79 pages |
| Authors:
Yew K Boey; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| This study investigated the progressive damage/failure of composite panels with open circular holes under progressive axial loading. A series of experiments was carried out to determine the failure in laminated specimens with and without circular holes under tensile and compressive loads, respectively. Different strain rate loading was applied to observe the rate effect on the damage initiation and propagation. Both uniform and non-uniform strain rate loads were applied to the ... |
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| Silicon-Containing Polymers and Composites |
29 Nov 2011 |
4 pages |
| Authors:
Joseph M Mabry; Brian M Moore; Raymond Campos; Vandana Vij; Gregory R Yandek; Timothy S Haddad; Sean M Ramirez; Andrew J Guenthner; Dana M Pinson; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE SPACE AND MISSILE PROPULSION DIV/PROPULSION MATERIALS APPLICATIONS BRANCH
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| There are many examples of improved oxidation-resistance in organic polymeric materials achieved through the incorporation of silicon-containing compounds. These compounds are often organically-modified particles, such as silicas, silicates, clays, or polyhedral oligomeric silsesquioxanes, which can be mechanically blended into a wide variety of polymer matrices. However, in order to achieve improved dispersion of the silicon phase, it is often desirable for the silicon-containing compound to be covalently bound to the ... |
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| Influence of Peripheral Architecture on the Properties of Aryl Polyhedral Oligomeric SilSesquioxanes (POSS) |
29 Nov 2011 |
3 pages |
| Authors:
Gregory R Yandek; Brian M Moore; Sean M Ramirez; Joseph M Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE SPACE AND MISSILE PROPULSION DIV/PROPULSION MATERIALS APPLICATIONS BRANCH
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| The peripheral architecture of Aryl Polyhedral Oligomeric Silsesquioxanes (POSS) plays a significant role in observed macroscopic properties including phase transitions, thermal stability, and solubility. A relationship between these properties and POSS packing efficiency is offered, providing evidence that peripheral interactions require consideration in resolving the observed phenomena. These interactions further assume a pivotal role in determining POSS phase behavior in host materials such as low molecular weight solvents and polymers. ... |
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| Analytical Yield Criterion for an Anisotropic Material Containing Spherical Voids and Exhibiting Tension-Compression Asymmetry |
Nov 2011 |
20 pages |
| Authors:
Joel B Stewart; Oana Cazacu; AIR FORCE RESEARCH LAB EGLIN AFB FL MUNITIONS DIRECTORATE
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| This paper is devoted to the development of a macroscopic anisotropic yield criterion for a porous material when the matrix material is incompressible, anisotropic and displays tension - compression asymmetry. The analytical yield criterion is obtained based on micromechanical considerations and non-linear homogenization. The matrix plastic behavior is described by the Cazacu et al. (2006) anisotropic yield criterion that is pressure-insensitive and accounts for strength-differential effects. Comparison between finite element ... |
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| Thermo-Elastic Nondestructive Evaluation of Fatigue Damage in PMR-15 Resin (Preprint) |
Nov 2011 |
8 pages |
| Authors:
J T Welter; E A Lindgren; R Hall; S Sathish; G P Tandon; N Schehl; M Cherry; V Nalladega; DAYTON UNIV OH
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| Thermoset polyimide resins are used as the polymer matrix in high temperature composites for aerospace applications such as engine shrouds. At these locations the components have to withstand high temperatures and significant vibration. A number of studies have investigated the effects of thermal exposure on mechanical properties of polyimide resins, and the effects of fatigue on thermoplastics have been discussed at length. However, the effects of fatigue on thermosets, in ... |
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| Interpreting and Responding to Intensified Site Characterization Results |
Nov 2011 |
29 pages |
| Authors:
Fred Payne; ARCADIS US CHARLOTTE MI
|
| High-resolution site characterization is being applied at an increasing number of sites especially large-plume sites with long-standing chlorinated solvent source zones. This allows us to improve remedy design and operation, but it can also add to the challenge of regulatory closure, particularly in jurisdictions that require all groundwater to reach MCLs including locations where groundwater cannot be extracted at rates that would allow use for water supply. Common patterns are ... |
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| Environmentally Compliant Vinyl Ester Resin (VER) Composite Matrix Resin Derived from Renewable Resources |
Nov 2011 |
50 pages |
| Authors:
Yongwoo Lee; R Kovar; U Shin; N Francis; W Collins; L Renna; QINETIQ NORTH AMERICA INC WALTHAM MA
|
| The prime objective of this limited-scope, phase I SERDP program was to demonstrate the feasibility of economically producing a sustainable, environmentally safe vinyl ester resin (SESVER) for military composite structures. These structures would be derived from biowaste materials: lignin, recovered from wood wastes, and glycerin, recovered from biodiesel wastes. These abundant source materials are renewable, low-cost and independent of the food supply. A key environmental objective was to eliminate use ... |
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| Physical and Mechanical Characterization of a Nano Carbon Infused Aluminum-Matrix Composite |
Oct 2011 |
16 pages |
| Authors:
Lloyd Brown; Peter Joyce; DAVID FORREST; Jennifer Wolk; NAVAL ACADEMY ANNAPOLIS MD DEPT OF MECHANICAL ENGINEERING
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| A nanocarbon-infused aluminum-matrix composite, termed covetic, has been developed by Third Millennium Metals, LLC, and we have evaluated the enhanced performance prospects for strength and electrical conductivity. This paper examines the effects of the nanoscale carbon on the physical, electrical and mechanical properties of the metal-matrix composite based on microscopy, hardness, quasi-static tensile strength, high strain-rate compression strength and electrical conductivity measurements. In the as-extruded condition (warm worked at 400 ... |
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| New Finite Element/Multibody System Algorithm for Modeling Flexible Tracked Vehicles |
AUG 2011 |
17 pages |
| Authors:
Paramsothy Jayakumar; Mike Letherwood; Ulysses Contreras; Ashraf M. Hamed; Abdel-Nasser A. Mohamed; Ahmed A. Shabana; ARMY TANK AUTOMOTIVE RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
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| Integration of large displacement FE/MBS algorithms is necessary for the development of efficient and detailed tracked vehicle models. ANCF finite elements allow for the development of new FE meshes that have linear connectivity and constant inertia. Dependent variables can be systematically eliminated at a preprocessing stage (no need for joint formulation in the MBS code). The constant inertia allows for the development of an optimum sparse matrix structure of the ... |
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| Technical Operations Support III (TOPS III). Delivery Order 0081: Novel Pitch Materials for High Thermal Conductivity Carbon Fibers, Foams and Composites - Phase 3 |
JUN 2011 |
30 pages |
| Authors:
Amod A. Ogale; CLEMSON UNIV SC
|
| The overall goal of this project was to control nanotexture of pitch precursors by the introduction nanomodifiers of different aspect ratios, thereby modifying the structure of the resulting fibers. The specific objectives were to: (i) Characterize the dispersion of nanoparticles and the microstructure of the fibers; (ii) Quantify the effect of nanomodification on fiber mechanical properties; and (iii) Develop an experimental protocol to measure and model the high thermal conductivity ... |
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| Dynamic Material Properties of Orthotropic Polymer and Molybdenum for Use in Next Generation Composite Armor Concept? |
JUN 2011 |
131 pages |
| Authors:
Jonathan R. Garner; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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| Dyneema HB-25 is an orthotropic polyethylene fiber-epoxy matrix material that is being investigated for use in a next generation layered armor concept. Dyneema was chosen due to its high variation in sound speeds in the through direction and along the fiber direction, thereby making it a good candidate for a wave spreading layer in our proposed armored layer concept. The shock properties in the through fiber direction have been investigated ... |
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| Contaminant Mass Transfer During Boiling in Fractured Geologic Media |
Apr 2011 |
120 pages |
| Authors:
Ronald W Falta; Lawrence C Murdoch; CLEMSON UNIV SC
|
| The DoD is responsible for cleanup of groundwater that is contaminated with chlorinated volatile organic compounds (CVOC) at thousands of sites. Many of these sites are underlain by fractured rocks or soils with significant matrix porosity. As dissolved CVOC and dense nonaqueous phase liquids (DNAPL) move through fracture networks, the CVOC diffuse into the lower permeability matrix materials, where they can remain for hundreds of years. Remediation options for treating ... |
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| Improving the Distortional Deformation Capabilities of Aerospace Composite Networks |
28 Feb 2011 |
189 pages |
| Authors:
Jeffrey S Wiggins; UNIVERSITY OF SOUTHERN MISSISSIPPI HATTIESBURG
|
| Currently, the University in collaboration with Boeing Research and Technology, through leveraged financial support provided by AFOSR has established a comprehensive academic research platform based upon the development and utilization of multi-scale computational methods for designing composite matrix network chemistries with enhanced thermo-mechanical performance. Molecular dynamics models have been combined with advanced solution-to-gel-solid state analytical techniques to enhance computational accuracy and validate their accuracy. Our research platform is using computational ... |
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| Cyanate Ester Resin Modified with Nano-particles for Inclusion in Continuous Fiber Reinforced Composites |
25 Feb 2011 |
58 pages |
| Authors:
Michael R Kessler; Prashanth Badrinarayanan; IOWA STATE UNIV AMES
|
| The mismatch in coefficient of thermal expansion (CTE) between the polymer matrix and low CTE carbon fibers causes development of residual stresses in polymer matrix composites (PMCs) that can lead to micro cracking and failure. This report describes the development of hybrid polymer composites comprising of a unique low viscosity bisphenol E cyanate ester resin (BECy) resin reinforced with macro scale carbon fibers and negative CTE nanoparticles. Polymer nanocomposites were ... |
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| Cyanate Ester Resin Modified with Nano-particles for Inclusion in Continuous Fiber Reinforced Composites |
25 Feb 2011 |
58 pages |
| Authors:
Michael R Kessler; Prashanth Badrinarayanan; IOWA STATE UNIV AMES
|
| The mismatch in coefficient of thermal expansion (CTE) between the polymer matrix and low CTE carbon fibers causes development of residual stresses in polymer matrix composites (PMCs) that can lead to micro cracking and failure. This report describes the development of hybrid polymer composites comprising of a unique low viscosity bisphenol E cyanate ester resin (BECy) resin reinforced with macro scale carbon fibers and negative CTE nanoparticles. Polymer nanocomposites were ... |
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| Cure Characteristics of Tricyanate Ester High Temperature Composite Resins (PREPRINT) |
09 FEB 2011 |
15 pages |
| Authors:
Andrew J. Guenthner; Kevin R. Lamison; Matthew C. Davis; Lee R. Cambrea; Gregory R. Yandek; Joseh M. Mabry; AIR FORCE RESEARCH LAB EDWARDS AFB CA PROPULSION DIRECTORATE
|
| Highly aromatic tricyanate ester resins exhibit glass transition temperatures well in excess of 350 degrees Celsius when thermally cured to full conversion. In many cases, though, complete conversion is difficult to achieve in practice due to the highly rigid nature of the molecules. A thorough understanding of the cure process is thus important for realizing the full potential of these materials. In order to characterize the cure of these systems ... |
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| Time Effects on Morphology and Bonding Ability in Mercerized Natural Fibers for Composite Reinforcement |
2011 |
10 pages |
| Authors:
T. WILLIAMS; M. Hosur; M. Theodore; A. Netravali; V. Rangari; S. Jeelani; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| Properties of cellulose-derived fibers are extremely sensitive to surface treatment. Many studies have investigated the effects of varying surface treatment parameters in natural fibers to improve fiber-matrix bonding; however, work is still needed to assist with developing better quality control methods to use these fibers in more load-bearing composites. Kenaf fibers were alkali treated,and the surface and morphology were analyzed to determine how treatment time affected the bonding sites in ... |
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| Nanostructured Self-Healing Polymers and Composites |
31 OCT 2010 |
8 pages |
| Authors:
Nancy R. Sottos; Paul V. Braun; ILLINOIS UNIV AT URBANA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Through this research, we successfully demonstrated self-healing with submicron and nanoscale consitutents. The research was driven by basic science and engineering of new processing routes for nanoencapsulation of healing chemistries and seamless integration of the self-healing functionality into polymer and polymer composites. Major accomplishments described in this report include - Identified three promising healing chemistries and successfully encapsulated the components in submicron capsules. - Functionalized the nanocapsules with a silica ... |
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| Mean-Field Models of Structure and Dispersion of Polymer-nanoparticle Mixtures |
29 JUL 2010 |
32 pages |
| Authors:
Venkat Ganesan; Christopher J. Ellison; Victor Pryamitsyn; TEXAS UNIV AT AUSTIN DEPT OF CHEMICAL ENGINEERING
|
| We review some recent research developments in coarse-grained modeling based on mean-field approaches of the equilibrium dispersion and structure of polymer nanoparticle composites. We focus on three issues: (i) dispersion and phase behavior of particles in homopolymer matrices; (ii) dispersion in mixtures of homopolymers with grafted nanoparticles; (iii) self-assembly and organization of nanoparticles in block copolymer matrices. In each of these topics, we highlight that the dispersability and the resulting ... |
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| Composite Materials and Sandwich Structures - A Primer |
May 2010 |
17 pages |
| Authors:
Mohan M Ratwani; R-TEC ROLLING HILLS ESTATE CA
|
| Improving the performance of aircraft and other military hardware is of prime concern to designers. The designers strive to build the military hardware which is light with improved performance and at the same time have low acquisition and life cycle costs. Recent developments in structures and materials technologies along with advancements in propulsion and flight control systems has resulted in quantum advancements in the performance of aircraft and other military ... |
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| Microstructural Design & Optimization of Highly Filled Epoxy Based Composites |
Nov-2009 |
45 pages |
| Authors:
Jennifer L Jordan; D W Richards; Jonathan E Spowart; Bradley White; Naresh N Thadhani; AIR FORCE RESEARCH LAB EGLIN AFB FL MUNITIONS DIRECTORATE
|
| The dynamic mechanical properties of multi-constituent particulate composites, consisting of individual Ni and Al particles dispersed in an epoxy matrix are investigated in this study. Properties of such composites depend on the mechanical and physical properties of the individual components; their loading density; the shape and size of the particles; the interfacial adhesion; residual stresses; and matrix porosity. These multi-phase particulate composites systems, particularly those with high fill densities, have ... |
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| Near-Infrared Collisional Radiative Model for Xe Plasma Electrostatic Thrusters: The Role of Metastable Atoms |
Aug-2009 |
10 pages |
| Authors:
Rainer A Dressler; Yu-Hui Chiu; Oleg Zatsarinny; Klaus Bartschat; Rajesh Srivastava; Lalita Sharma; AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE
|
| Metastable Xe atoms play an important role in the collisional radiative processes of dense xenon plasmas, including those of electric thrusters for space vehicles. Recent measurements and calculations of electron-excitation processes out of the metastable state have allowed for the development of a collisional radiative model for Xe near-infrared (NIR) emissions based on the population of the metastable level through radiative transitions, and based on depopulation through electron-impact excitation. A ... |
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| High Temperature Epoxy Nanocomposites for Aerospace Applications |
10-Jun-2009 |
13 pages |
| Authors:
Dharmaraj Raghavan; Chen Chenggang; HOWARD UNIV WASHINGTON DC DEPT OF CHEMISTRY
|
| The primary objective of this research is to make nanocomposites with the incorporation of thermally stable silicate nanolayers in the polymer matrix. Several functionalized imidazolium clays, functionalized anionic clays, and silylated apophylites were synthesized and characterized by XRD and TGA. Thermal studies of functionalized clay have shown that the onset decomposition temperature of imidazolium functionalized clay (325 deg C), alpha amino napthononate exchanged layered double hydroxide (NLDH) (approx. 300 deg ... |
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| The Use of Commercial Non-Hazardous Air Pollutant Monomers to Optimize the Properties of Fatty Acid-Based Resins |
May-2009 |
34 pages |
| Authors:
La; John J Scala; Priya Kamath; Anita Sahu; Giuseppe R Palmese; James M Sands; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Vinyl ester (VE) resins are used to make polymer matrix composites in military and commercial applications because of their good properties, low weight, and low cost. These resins typically contain high concentrations of reactive diluents, such as styrene, to allow these resins to be molded using resin transfer molding and other inexpensive liquid molding techniques. Because styrene is a hazardous air pollutant (HAP) and a volatile organic compound (VOC), the ... |
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| A Non-Linear Finite Element Model for the Determination of Elastic and Thermal Properties of Nanocomposites |
Apr-2009 |
107 pages |
| Authors:
Paul Elsbernd; RICE UNIV HOUSTON TX
|
| This thesis presents a non-linear model for the thermal and elastic properties of single-walled carbon nanotube reinforced polymer composites. Finite Element Analysis (FEA), in conjunction with the Embedded Fiber Method (EFM), is used to calculate the effective stress-strain curve and thermal conductivity of the composite material. First, the geometry of a user-defined volume fraction of nanotubes is randomly generated and their properties are incorporated into the polymer matrix using the ... |
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| Radiometric Measurements on Ag/n-Si Composite Films for Detecting Radiation in the Earth's Atmospheric Windows |
20-Feb-2009 |
3 pages |
| Authors:
Bates; Clayton W Jr; HOWARD UNIV WASHINGTON DC
|
| The objectives of the research proposed in this 10-month effort were to assemble optical absorption and radiometric facilities for measuring the properties of Ag/n-Si composite films that are to be used as infrared detectors in the earth's atmospheric windows (1-2, 3-5, and 8-12 microns) from room temperature down to liquid nitrogen temperature and to begin making these measurements on films with specific microstructures. All of the equipment requested in the ... |
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| Innovative Energy Absorbing Mounting Systems for High Mass Rotorcraft Payloads |
Dec-2008 |
9 pages |
| Authors:
William Kong; Chandrashekhar Tiwari; Matthew J Hagon; Charles E Bakis; Edward C Smith; Michael A Yukish; PENNSYLVANIA STATE UNIV UNIVERSITY PARK
|
| This paper presents recent developments on two innovative types of crashworthy cargo restraints for high mass rotorcraft payloads: textile-based devices and flexible matrix composite devices. Each type of device employs energy dissipation mechanisms to arrest the motion of payloads and limit the maximum load transmitted to tie-down points, thereby maintaining control over payload motion and improving crew survivability in the event of a crash or hard landing. The benefit of ... |
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| Creep Behavior of Oxide/Oxide Composites with Monazite Fiber Coating at 1100 deg C in Air and in Steam Environments |
01-Sep-2008 |
425 pages |
| Authors:
Tufan Yeleser; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The creep behavior of six oxide-oxide ceramic-matrix composites (CMCs) was investigated at 1100C in air and in steam. The six CMC systems had an alumina matrix reinforced with Nextel (TradeMark)610 fibers. The CMC systems C1, C2 and C3 were reinforced with 10 uni-directional fiber layers in a symmetric cross-ply orientation while C4, C5,and C6 were reinforced with 8 plies of fiber fabric woven. Composites C2, C3, C4, and C6 had ... |
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| Multifunctional Properties of Structural Gel Electrolytes |
01-Sep-2008 |
18 pages |
| Authors:
P-A T Nguyen; J F Snyder; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Multifunctional structural gel electrolytes were prepared by the integration of conductive pathways using non-aqueous solvents into structural resin networks. Poly(ethylene) glycol (200 MW) and propylene carbonate were used as non-aqueous solvents while vinyl ester and epoxy resin were used as structural resins. The monomer and solvents were incorporated together and polymerized to create conductive pathways is crosslinked networks. THe impact of chemistry and weight fraction of both liquid and resin ... |
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| Evaluation of Nanocomposites as Lightweight Electronic Enclosures for Satellites' Applications |
JUN 2008 |
98 pages |
| Authors:
Benjamin T. Harder; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The United States military is exploring the use of nanocomposite materials for satellite structural applications. Current composite spacecraft structures are nonconductive and must have expensive shielding materials applied in order to protect the spacecraft from catastrophic damage that can be caused by electromagnetic interference (EMI) and/or electrostatic discharge (ESD) which are characteristics of the space environment. Conductive nanocomposites are being developed for spacecraft structures that will provide ESD and EMI ... |
|
| FASST Soil Moisture, Soil Temperature: Original Versus New |
01-Apr-2008 |
36 pages |
| Authors:
Susan Frankenstein; ENGINEER RESEARCH AND DEVELOPMENT CENTER HANOVER NH COLD REGIONS RESEARCH AND ENGINEERING LAB
|
| This paper discusses only the differences between the original version of FASST (Frankenstein and Koenig 2004a, 2004b) and the new version. This report is intended as a supplement to the original model documentation. In its original incarnation, energy and mass transport associated with water vapor in the soil matrix were ignored. The author added these so that model usage could be expanded to include biological investigations yet still retain its ... |
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| Nanostructured Shape Memory Alloys: Adaptive Composite Materials and Components |
DEC 2007 |
19 pages |
| Authors:
Wendy C. Crone; Arthur B. Ellis; John H. Perepezko; WISCONSIN UNIV-MADISON BOARD OF REGENTS/RESEARCH SPONSORED PROGRAMS
|
| Methods for fabricating adaptive composite materials and components using shape memory alloy (SMA) constituents were investigated using a variety of fabrication techniques, including mechanical rolling methods. Both SMA-polymer and SMA-metal composites were created, as well as new fabrication strategies for producing NiTi and CuAlNi shape memory alloy particles with refined size which still display shape memory and pseudoelasticity. The composite materials show promising fracture toughness behavior. The functionalization strategy we ... |
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| Precision Composite Space Structures |
15 OCT 2007 |
306 pages |
| Authors:
Mark R. Garnich; DAVID LONG; John F. Fitch; Akula M. Venkata; Pu Liu; WYOMING UNIV LARAMIE
|
| This project was aimed at developing analytical approaches to improving and better understanding the dimensional stability or composite space structures under thermal environments and changing material behavior due to microscopic damage. A comprehensive review or the literature on damage modeling or polymer matrix composite laminates was conducted. Damage due to matrix cracking was characterized using micromechanics. Aspects of predicting and utilizing degraded properties at the fiber and matrix level were ... |
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| Tensile Creep and Fatigue of Sylramic-iBN Melt-Infiltrated SiC Matrix Composites: Retained Properties, Damage Development, and Failure Mechanisms (Preprint) |
Oct-2007 |
32 pages |
| Authors:
Gregory N Morscher; Greg Ojard; Robert Miller; Yasser Gowayed; Unni Santhosh; Jalees Ahmed; Reji John; PRATT AND WHITNEY EAST HARTFORD CT
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| The elevated temperature creep, fatigue, rupture, and retained properties of ceramic matrix composites envisioned for use in gas turbine engine applications are essential properties to understand and model for the purposes of component design and life-prediction. In order to quantify the effect of stress, time, temperature, and oxidation for a state-of-the-art composite system: the Sylramic-iBN woven fiberreinforced, BN interphase, melt-infiltrated SiC matrix composite, a wide variety of tensile creep, dwell ... |
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| Optimization, Alternative Materials and Improvements in Body Armor Shields |
10-May-2007 |
30 pages |
| Authors:
R C Batra; G M Zhang; J Zheng; G Gopinath; VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF ENGINEERING SCIENCE AND MECHANICS
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| In the first part of the work, we analyze, with the computer code LS-DYNA, three-dimensional (3D) transient deformations of a 10-layer woven Kevlar armor held in a square steel frame and impacted at normal incidence by a 9 mm FMJ (full metal jacket), 124 grain projectile. The composite armor is discretized into weft and warp yarns to simulate its woven structure. The yarn is modeled as a 3D continuum. We ... |
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| Self Assembled, Ultra-Hydrophobic Micro/Nano-Textured Surfaces |
APR 2007 |
26 pages |
| Authors:
Adam M. Rawlett; Joshua A. Orlicki; Nicole Zander; Afia Karikari; Tim Long; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
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| The formation of hierarchically ordered arrays of spherical cavities on polymer films is of interest due to potential applications in the reparation of photonic bandgaps materials, environmental sensors, and patterned light-emitting diodes. While many methods are known for the preparation of these porous materials, the breath figure approach has received significant scrutiny because of the simple and robust mechanism of pattern formation. Breath figures are patterned arrays of micrometer-sized defects ... |
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| Perfect Storm: Analyzing Strategic Issues Confronting Program Executive Office, Missiles and Space |
30-Mar-2007 |
98 pages |
| Authors:
Joseph S Anderson; David A Warnick; NAVAL POSTGRADUATE SCHOOL MONTEREY CA GRADUATE SCHOOL OF BUSINESS AND PUBLIC POLICY
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| This MBA Project analyzed the following four strategic issues surrounding Program Executive Office Missiles and Space: the implementation of Program Budget Decision 753, the deterioration of the matrix support structure, the aging of the civilian workforce, and the influx of new organizations resulting from the Base Realignment and Closure process. The goals of this project were to conduct an analysis of the interrelationships among several strategic problems and challenges facing ... |
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| Nanotechnology in Aerospace Applications |
01-Mar-2007 |
38 pages |
| Authors:
M Meyyappan; MM ASSOCIATES MOFFETT FIELD CA
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| Effects of Temperature and Environment on Creep Behavior of an Oxide-Oxide Ceramic Matrix Composite |
MAR 2007 |
267 pages |
| Authors:
Jason C. Braun; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH DEPT OF AERONAUTICS AND ASTRONAUTICS
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| This research investigated the creep behavior of an N720/Al203 composite. The composite consists of a porous alumina matrix reinforced with laminated, woven mullite/alumina fibers (NextelTM 720). This ceramic matrix composite (CMC) has no fiber coating and relies on the porous matrix for flaw tolerance. The tensile stress-strain behavior was investigated and the tensile properties measured in the 800-1100 ?C temperature range. Tensile creep behavior was examined at 1000 and 1100 ... |
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Reports by Keyword(s)
MATRIX MATERIALS
