| Foundation Elements for Naval Low-Rise Buildings |
Oct-2009 |
201 pages |
| Authors:
Mark Hatch; Michael P Wolcott; WASHINGTON STATE UNIV PULLMAN WOOD MATERIALS AND ENGINEERING LAB
|
 | Natural fiber composites are commonly used in residential decking, siding, and fencing applications, but their use in high-load structural applications has been limited by their low strength performance. However, wood-plastic composites (WPCs) consisting of nylon 12 and thermoplastic epoxy resin (TPER) exhibit excellent mechanical performance. This study evaluated the extrusion parameters for each composite including: barrel/die temperature profile, lubricant compatibility, wood flour (WF) content, and WF moisture content (MC). Increases ... |
|
| Thermomechanical Properties of Center-Reinforced Aluminum |
Mar-2009 |
300 pages |
| Authors:
Geofrey S Cox; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The rule of mixture approach was shown to produce an accurate theoretical prediction of the room temperature elastic modulus values when compared to the experimental results. The laminate's modulus value remained relatively constant over the -55C to 80C temperature range, indicating stable behavior despite temperature changes. Blunt notch tests also revealed that the laminate's strength was not significantly reduced due to the presence of small holes. Finally, fatigue testing demonstrated ... |
|
| Tunable Interfaces in Fiber Reinforced-Polymer Composites Using Plasma Surface Treatments |
Dec-2008 |
7 pages |
| Authors:
Alexander Fridman; Giuseppe R Palmese; Jacqueline H Yim; D D Pappas; Denis Kissounko; DREXEL UNIV PHILADELPHIA PA DEPARTMENT OF CHEMICAL AND BIOLOGICAL ENGINEERING
|
| Fibers incorporated into polymer matrices suffer from poor adhesion at the fiber-resin interface. In ballistic materials such as body armor, it is imperative that the fiber-resin interface is strengthened for superior energy absorbing capabilities. To address this need, fibers are typically subjected to surface modifications. The overall aim of this work is to establish a methodology of controlling the interfacial adhesion by controlling the degree of chemical bonding between the ... |
|
| Multiscale Models of Multifunctional Composites for On-Board Damage Detection and Failure Prevention |
08-Oct-2008 |
12 pages |
| Authors:
W A Curtin; BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING
|
| Analytic and numerical models were developed to predict the dependence of electrical resistance on internal fiber damage in carbon-fiber-reinforced polymer (CFRP) composites, so as to make electrical resistance measurement a tool for damage detection and prognosis in CFRP components. The models show that electrical resistance is more sensitive to damage than elastic modulus, that resistance change can be used to detect inadvertent overloads, that the remaining fatigue life after overload ... |
|
| Hybrid Carbon-Glass Fiber/Toughened Epoxy Thick Composite Joints Subject to Drop-Weight and Ballistic Impacts |
DEC 2007 |
78 pages |
| Authors:
Benjamin Liaw; Feridun Delale; CITY COLL NEW YORK DEPT OF MECHANICAL ENGINEERING
|
| This ARO project from City College of City University of New York (CCNY of CUNY) was submitted in response to ARO's FY 2002 DoD Instrumentation and Research Support for Hispanic Serving Institutions (HSIs), BAA No. DAAD19-02-R-0010 to conduct research on hybrid carbon-S2 glass fiber/toughened epoxy thick-section, hybrid interwoven composite joints subject to drop-weight and ballistic impacts. Dr. Basavaraju B. Raju of U.S. Army TACOM-TARDEC was the research collaborator and Dr. ... |
|
| Dynamic Response and Simulations of Nanoparticle-Enhanced Composites |
15 NOV 2007 |
246 pages |
| Authors:
P. R. Mantena; Ahmed Al-Ostaz; Alexander H. Cheng; MISSISSIPPI UNIV UNIVERSITY MS COMPOSITE STRUCTURES AND NANO ENGINEERING RESEARCH GROUP
|
| Objectives of this research are to characterize the: (a) vibration and acoustic response; (b) low-velocity impact and high-strain energy absorption; (c) effects of freeze-thaw cycling; and (d) molecular dynamics simulations of nanoparticle-enhanced composites and fly- ash based foams that are being considered for the future generation naval structures or retrofitting of existing ones. In this study, the flexural/extensional dynamic modulus, damping, low-velocity impact and high-strain (Hopkinson bar) response of nylon ... |
|
| Nanocomposites for Enhanced Structural Integrity |
11 SEP 2007 |
12 pages |
| Authors:
H. T. Hahn; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| The main objective of the proposed research was to develop the science base necessary for full utilization of nanoreinforcements into polymers and fiber composites to improve mechanical, thermal and electrical properties. Two types of nanoreinforcements were studied: 0-dimensional SiC nanoparticles and 2-dimensional graphite nanoplatelets. As property improvements are possible only when the nanoreinforcements are uniformly dispersed in and well bound to the polymer matrix, the emphasis was on developing methods ... |
|
| Electromagnetic Shielding Effectiveness Analysis of Nanoreinforced Polymer Composites |
22 AUG 2007 |
4 pages |
| Authors:
Karen Lozano; Arturo Fuentes; TEXAS UNIV-PAN AMERICAN EDINBURG
|
| The team conducted dielectric analysis of samples to promote a better understanding of the mechanisms involved in changes in dielectric structure of microstructures exposed to varying frequency fields and temperatures. The results were published as S. Yang, R. Benitez, A. Fuentes, and K. Lozano, "Dielectric Analysis of VGCNF Reinforced Polyethylene Composites," Composite Science and Technology, Vol. 67, No. 6, p. 1159 (2007). A journal article also was published relating to ... |
|
| Extending the Performance of Net Shape Molded Fiber Reinforced Polymer Composite Valves for Use in Internal Combustion Engines |
JUN 2007 |
367 pages |
| Authors:
Richard T. Buckley; COLORADO STATE UNIV FORT COLLINS DEPT OF MECHANICAL ENGINEERING
|
| Fiber Reinforced Composite (FRC) materials offer the possibility of reduced mass and increased performance over metals. Used in internal combustion engines, this may enable increased power and mechanical efficiency. Previous work has both shown structural and thermal limitations. A net-shape resin transfer molded intake valve has been developed, using a single-piece carbon fiber preform and the high temperature polymer PETI-RFI. Performance has been validated through testing. High engine load conditions ... |
|
| Micro-Stress Bound Estimate Enabled Optimization of Structural Composite Repair for the Next Generation Aircraft |
28 FEB 2007 |
42 pages |
| Authors:
Endel V. Iarve; Robert Lipton; DAYTON UNIV OH
|
| The completed effort integrated the rigorous microlevel (fiber, matrix, sizing) stress bound recently obtained by Lipton [1,2] under AFOSR sponsorship with the AFRL-developed ply level multibasis spline approximation stress analysis tools [3-5]. A robust multiscale analysis framework was developed and applied within and beyond the scope of the present grant. The developments included extension of the stress bound estimates in heterogeneous materials with periodic microstructure to include residual stress effects ... |
|
| Challenges and Opportunities for Nanotechnology in Multi-Functional Composite Structures (Preprint) |
NOV 2006 |
18 pages |
| Authors:
Jeff Baur; Edward Silverman; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH STRUCTURAL MATERIALS BRANCH/NONMETALLIC MATERIALS DIV
|
| Incorporation of nanoparticles into engineered composites represents one of the largest volume applications for nanocomposites currently envisioned. Of the wide variety of structural applications, fiber-reinforced composites for aerospace structures have some of the most demanding applications with extreme requirements in physical, chemical, electrical, thermal, and mechanical properties. Nanocomposites offer tremendous potential to improve these properties for advanced engineered composites with modest additional weight and easy integration into current processing schemes. ... |
|
| Prestressed Carbon Fiber Composite Overwrapped Gun Tube |
NOV 2006 |
30 pages |
| Authors:
Andrew Littlefield; Edward Hyland; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| The emphasis on lightweight large caliber weapons systems has placed the focus on the use of advanced composite materials. Using composite materials not only directly removes weight from the gun tube but, by better balancing the tube, allows the use of smaller drive systems, thus further enhancing the system weight loss. Additionally the use of high stiffness composites helps with pointing accuracy and to alleviate the dynamic strain phenomenon encountered ... |
|
| Geopolymers for Structural Ceramic Applications |
31 AUG 2006 |
145 pages |
| Authors:
Douglas C. Comrie; CATAWBA RESOURCES STOW OH
|
| Geopolymers show promise in a variety of structural ceramic based application including refractory adhesives for ceramics and metals, thermal shock resistant molds, fiber reinforced composites, and as a precursor in the formation of pure ceramic phases such as leucite (KA1Si(sub 2)O(sub 6) and pollucite (CsA1Si(sub 2)O(sub 6) with tailorable porosity and thermal expansion. In this work, the scientific details of using geopolymers in these emerging areas were explored via mechanical ... |
|
| Low Temperature, Low Pressure Fabrication of Ultra High Temperature Ceramics (UHTCs) |
AUG 2006 |
116 pages |
| Authors:
Yigal Blum; Jochen Marschall; Hans J. Kleebe; SRI INTERNATIONAL MENLO PARK CA
|
| The US Air Force is interested in developing fiber-reinforced ceramic composites that perform at ultra-high temperatures (greater or more than 1500 degrees C) under oxidative conditions, especially for hypersonic vehicles. Two potential approaches are: (a) Utilizing existing carbon-fiber-reinforced carbon-matrix composites (C/C) or carbon-fiber-reinforced silicon carbide-matrix composites (C/SiC) coated by thick (>100 um) ultra-high temperature ceramic (UHTC) coatings, or (b) Replacing the C and SiC matrices of such composites with an ... |
|
| Nano-Particle Control of Void Formation and Expansion in Polymeric and Composite Systems |
JUL 2006 |
11 pages |
| Authors:
James C. Seferis; WASHINGTON UNIV SEATTLE DEPT OF CHEMICAL ENGINEERING
|
| The research focused on carbon fiber reinforced epoxy composites with varying dispersions of montmorillonite and nanoprosity, processed with either prepreg or Vacuum Resin Transfer Mold (VARTM) technologies. The most significant advancements and conclusions in this final report include interlayer modification of composites at the nanoscale and characterization of the interlayer behaviour of nanoparticles and nanoporous composites, as well as VARTM processing of nanoclay filled composites. |
|
| Development of Deployable Elastic Composite Shape Memory Alloy Reinforced (DECSMAR) Structures |
MAY 2006 |
|
| Authors:
Eric L. Pollard; Thomas W. Murphey; CSA ENGINEERING INC ALBUQUERQUE NM
|
 | The objective of this research is to develop a novel. self-deployable truss architecture composed of carbon fiber reinforced plastic (CFRP) tape-spring elements and embedded shape memory alloy (SMA) flexures; this particular structural system is referred to as deployable elastic composite shape memory alloy reinforced (DECSMAR) and is representative of a concentrated, material deformation based deployable architecture. The scope of this study encompasses applying fundamental principles of rational boom design relevant ... |
|
| Naval Prototype Optical Interferometer (NPOI) Upgrade with Lightweight Telescopes and Adaptive Optics: A Status Update |
Apr-2006 |
9 pages |
| Authors:
Tom Armstrong; Sergio R Restaino; Jonathan R Andrews; Christopher C Wilcox; Robert Romeo; Robert Martin; NAVAL RESEARCH LAB KIRTLAND AFB NM REMOTE SENSING DIV
|
| The portability of meter-class telescopes has been limited by the weight of the mirror, tube assembly, and the mount required to provide pointing and tracking. The novel lightweight carbon fiber-reinforced polymer telescopes being developed for array population at the Naval Prototype Optical Interferometer are orders of magnitude lighter than traditional telescopes. When combined with a lightweight carbon fiber mount, these telescopes will be easily transportable from one telescope station to ... |
|
| Composites Reinforced with Short Wavy Fibers |
01 MAR 2006 |
30 pages |
| Authors:
C. T. Sun; J. Cho; A. Deo; PURDUE UNIV LAFAYETTE IN
|
| In short fiber composites including nanocomposites, the load transfer efficiency among fibers is crucial in effecting superior composite properties. It is conceivable that this load transfer efficiency depends on the shape, aspect ratio, and surface area of the fiber. The effect of surface area of the reinforcing element is of particular importance because of the increasing use of nanoparticles in nanocomposites. It is well known that for the some volume, ... |
|
| Probabilistic Analysis for the Mechanical Properties of Cross-Ply Fiber-Reinforced Composite Laminate (Postprint) |
MAR 2006 |
15 pages |
| Authors:
Shui-Nan Chuang; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| A probabilistic micromechanics model has been developed for the unidirectional fiber-reinforced composite material design screening. This model provides a design-screening tool to help material producers eliminate the unnecessary time-consuming and costly material fabrications and to reduce the numbers of testing to a minimum, but enough to verify the model prediction. Consequently, it provides a means to accelerate the insertion of materials into AF productions. To include the material design in ... |
|
| Hybrid Fiber Sizings for Enhanced Energy Absorption in Glass-Reinforced Composites |
JAN 2006 |
38 pages |
| Authors:
Robert E. Jensen; Steven H. McKnight; Dave P. Flanagan; Alan R. Teets; Donovan Haiiis; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Achieving high-impact energy absorption without loss of structural performance in a glass fiber-reinforced composite can be obtained through a "materials by design" approach of the fiber matrix interphase through modification of current commercially formulated silane-based fiber-sizing packages. In this report, we document our attempt to balance the structural and impact performance of glass-reinforced composites produced using a fiber-sizing package composed of mixed silane coupling agents to vary the reactivity of ... |
|
| 2-D Biaxial Testing and Failure Predictions of IM7/977-2 Carbon/Epoxy Quasi-Isotropic Laminates |
2006 |
8 pages |
| Authors:
Jeffery S. Welsh; J. S. Mayes; Adam C. Biskner; AIR FORCE RESEARCH LAB KIRTLAND AFB NM SPACE VEHICLES DIRECTORATE
|
| In previous research, a series of a thickness-tapered cruciform specimen configurations have been used to determine the biaxial (two-dimensional, in-plane) and triaxial (three-dimensional) strength of several carbon/epoxy and glass/vinyl-ester laminate configurations. Refinements to the cruciform geometry have been shown capable of producing acceptable results for cross-ply laminate configurations. However, the presence of a biaxial strengthening effect in quasi-isotropic, laminates have brought into question whether the cruciform geometry could be used ... |
|
| Synthesis and Mirostructural Design of Oxide Fibers |
31 DEC 2005 |
7 pages |
| Authors:
Wonki Yoon; Waltraud M. Kriven; ILLINOIS UNIV AT URBANA DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| Fine ceramic oxide fibers are widely used as reinforcements in composites for high temperature applications. The primary goal of this research effort was to investigate the growth of single crystal or textured or eutectic oxide fibers by heat treatment of polycrystalline or amorphous precursor fibers. |
|
| Mechanics of the Fiber-Matrix Interphase Push-Out Test |
SEP 2005 |
20 pages |
| Authors:
Xiaogang Huang; Maureen E. Foley; Travis A. Bogetti; Jr Gillespie John W.; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| The stress distribution for the fiber-matrix interphase push-out test is derived. The analytical solution provides the mechanics foundation to relate experimental measurements to the properties of the interphase. The shear-lag model incorporates a discrete interphase region quantified by the thickness and shear modulus of the interphase. Except for the basic shear-lag model assumptions, the method follows a rigorous mathematical approach. Accuracy of the analytical solution is assessed using finite element ... |
|
| The Use of Fiber-Reinforced Polymer-Matrix Composites in Army Ground Vehicles |
07 APR 2005 |
10 pages |
| Authors:
Adria N. Socks; TACOM RESEARCH DEVELOPMENT AND ENGINEERING CENTER WARREN MI
|
| Polymer-matrix composites have been researched and studied for over 20 years regarding their applications to Army ground vehicles. Although much research has been performed only a few fiber-reinforced polymer-matrix composites are actually in service today. Evolving vehicle requirements however, will necessitate the implementation of these composites. This paper provides information regarding past, present and future applications for fiber-reinforced polymer-matrix composites. |
|
| Investigation of Lightning and EMI Shielding Properties of SWNT buckypaper Nanocomposites |
03 FEB 2005 |
18 pages |
| Authors:
Ben Wang; Richard Liang; Chuck Zhang; Leslie Kramer; Percy Funchess; FLORIDA AGRICULTURAL AND MECHANICAL UNIV TALLAHASSEE
|
| In this exploratory research project, a unique technical approach was developed to incorporate SWNTs buckypaper materials into conventional fiber- reinforced and foam composite structures for improving EMI and lightning strike protection properties. The EMI shielding and lightning strike attenuation properties of the composites with the surface layer of SWNT buckypaper nanocomposite were preliminarily characterized. Four types of the designed EMI/ lightning strike testing composite samples with buckypapers were produced. Each ... |
|
| Multifunctional Carbon Nanotube Fiber Composites |
26 DEC 2004 |
148 pages |
| Authors:
Ray H. Baughman; Steve Collins; Gordon G. Wallace; Joseph N. Barisci; Mikhail Kozlov; Yuri Gartstein; Alan G. Rinzler; Anvar A. Zakhidov; Rishi Raj; Miklos Kertesz; Alan B. Dalton; Chee Too; TEXAS UNIV AT DALLAS RICHARDSON
|
| The project provides a spinning process that results in continuous nanotube composite fibers that are about an order of magnitude tougher than any fibers made by mankind or nature. We make two hundred-meter long reels of continuous nanotube-polymer composite fiber at 70X the prior-art rate and achieve fiber strengths higher than 1.8 GPa. Our drawn nanotube fibers match the energy absorption capability of spider silk up to the breaking strain ... |
|
| Nanocomposites for Carbon Fiber Reinforced Polymer Matrix Composites |
26 OCT 2004 |
34 pages |
| Authors:
J. H. Koo; L. A. Pilato; G. Wissler; A. Lee; A. Abusafieh; TEXAS UNIV AT AUSTIN DEPT OF MECHANICALENGINEERING
|
| The major objective of this material program is to develop an improved epoxy nanocomposite for carbon fiber-reinforced polymer matrix composite (CPMC) with higher temperature performance capability, mechanical performance, damage resistance, extreme environment corrosion resistance, and improved dimensional control. We proposed that a nanophase be introduced into specific components of an epoxy resin system, prior to cure, to provide improved Tg and mechanical strength of the composites. In this study, we ... |
|
| Hybrid Fiber Sizings for Enhanced Energy Absorption in Glass-Reinforced Composites |
JUL 2004 |
45 pages |
| Authors:
Robert E. Jensen; Steven H. McKnight; Dave P. Flanagan; Alan R. Teets; Donovan Harris; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Achieving high-impact energy absorption without loss of structural performance in a glass fiber-reinforced composite can be obtained through a materials by design approach of the fiber matrix interphase through modification of current commercially formulated silane-based fiber-sizing packages. In this report, we document the structural and impact performance of composites produced using a fiber-sizing package designed to provide strong fiber-matrix bonding at low-impact rates and weak fiber-matrix bonding at high-impact rates. ... |
|
| Strengthening of Concrete Beams With Fasteners and Composite Material Strips-Scaling and Anchorage Issues |
JUL 2004 |
154 pages |
| Authors:
Lawrence C. Bank; David T. Borowicz; Dushyant Arora; Anthony J. Lamanna; Gerardo I. Velazquez; ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
|
| A system to rapidly strengthen concrete beams and slabs, known as the Mechanically-Fastened Fiber-Reinforced Polymer (MF-FRP) system, has been developed. In the fourth year of research on the subject, the focus was on scaling and anchorage issues. The effect of increasing the number of strips, the fastener spacing, termination distances, and the use of expansion anchors at the strip ends were considered. The scaling study also investigated the use of ... |
|
| Composite Replacement Panel Strain Survey (CRPSS) - Test Plan |
JUL 2004 |
|
| Authors:
Paul Callus; Anthony Harper; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) PLATFORM SCIENCES LAB
|
| The Defence Science and Technology Organisation in collaboration with the Cooperative Research Centre for Advanced Composite Materials, is developing the capability to replace metallic aircraft panels with those manufactured from advanced fibre composites. This is known as the Composite Replacement Panel Technology (CRPT). One step toward airworthiness certification of the CRPT is a validated capability to predict strain within a composite replacement panel (CRP) and the aircraft sub-structure. The strain ... |
|
| Microstructural Studies of In-Situ Mesophase Transformation in the Fabrication of Carbon-Carbon Composites |
29 APR 2004 |
9 pages |
| Authors:
K. M. Chioujones; W. Ho; P. C. Chau; B. Fathollahi; P. G. Wapner; ENGINEERING RESEARCH AND CONSULTING INC(ERC INC) EDWARDS AFB CA
|
| Injection of a low viscosity mesophase pitch into CVD-rigidized preforms can be an effective approach for fabrication of carbon-carbon composites. Here flow-induced microstructures are stabilized by oxidation such that upon carbonization the fibrous carbon needles running through the flow channels are retained. While the injection method is effective in making highly densified materials with controlled microstructure it is not without limitations. The method is best applied to well-defined geometries such ... |
|
| Monotonic, Creep-Rupture, and Fatigue Behavior of Carbon Fiber Reinforced Silicon Carbide (C/SiC) at an Elevated Temperature |
MAR 2004 |
127 pages |
| Authors:
John M. Engesser; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| The main objective of this research effort was to examine the impact that cyclic loading frequency has on the life of a C/SiC composite at an elevated temperature of 550 C. Cyclic loading of C/SiC was investigated at frequencies of 375 Hz, 10 Hz, 1 Hz, and 0.1 Hz. Creep-Rupture tests and tests that were combinations of creep-rupture and fatigue were also accomplished. A monotonic tensile test was performed at ... |
|
| Dynamic Cracking and Energy Absorption in Laminates Containing Through- Thickness Reinforcement |
FEB 2004 |
177 pages |
| Authors:
Brian N. Cox; Sridhar Narayanaswamy; ROCKWELL SCIENTIFIC CO THOUSAND OAKS CA
|
| Inertial effects in the mechanism of fiber pullout were examined, with emphasis on how the rate of propagation of stress waves along the fiber, and thence the pullout dynamics, are governed by friction and the propagation of companion waves excited in the matrix. The frictional sliding between the fiber and the matrix is described by a constant interfacial friction stress, the sign of which depends on the relative particle velocity ... |
|
| Development of Composites Reinforced with Short Wavy Fibers |
2004 |
8 pages |
| Authors:
C. T. Sun; PURDUE UNIV LAFAYETTE IN
|
| In short fiber composites including nanocomposites, the load transfer efficiency among fibers is crucial in effecting superior composite properties. It is conceivable that this load transfer efficiency depends on the shape, aspect ratio, and surface area of the fiber. The effect of surface area of the reinforcing element is of particular importance because of the increasing use of nano particles in nanocomposites. It is well known that for the same ... |
|
| The Effects of Physical Composite Particle Parameters on The Efficacy of a Proprietary Sound-Attenuation Technology and it's Application to Advanced Structural Composites |
28 MAR 2003 |
6 pages |
| Authors:
Chuck Zhang; FLORIDA AGRICULTURAL AND MECHANICAL UNIV TALLAHASSEE COLLEGE OF ENGINEERING
|
| Two principal objectives were proposed in this research: (1) determine the acoustical effects of the filler materials with different sound impedance in composites fabricated according to a proprietary technology, and (2) determine the feasibility of applying the proprietary technology to continuous fiber-reinforced advanced structural composites. The sequential experimental approach began by attempting to apply the acoustical technology with neat epoxies using off-the-shelf filler materials possessing a range of physical characteristics. ... |
|
| Guidelines for the Development of Process Specifications, Instructions, and Controls for the Fabrication of Fiber-Reinforced Polymer Composites |
MAR 2003 |
48 pages |
| Authors:
Gregg Bogucki; William McCarvill; Stephen Ward; John Tomblin; WICHITA STATE UNIV KS INST FOR AVIATION RESEARCH
|
| This document provides (1) a set of guidelines for the development of process specifications for the fabrication of continuous fiber-reinforced polymer composite laminate test panels used in the generation of mechanical properties and (2) an approach for the validation of composite fabrication processes used during the certification of composite aircraft structure. These guidelines were prepared by a team of industry experts. Guidelines are given based on processes and sound engineering ... |
|
| Experimental and Computational Failure Analysis of Graphite/Bismaleimide Laminated Composite and Carbon Foam in Sandwich Construction |
MAR 2003 |
91 pages |
| Authors:
Troy C. Welker; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
|
| Sandwich beams consisting of a carbon foam core and graphite/ bismaleimide face sheets were constructed and tested. Nine specimens were fabricated using three distinct cross-ply symmetric face sheet layups with a constant core thickness. Four-point bend testing controlled by a constant rate of midspan vertical displacement was used to load the specimens to failure. Displacements and strains from the experiment were compared to analytical sandwich beam theory and displacements and ... |
|
| Nanocomposite Fibers |
2003 |
6 pages |
| Authors:
Yong K. Kim; Armand F. Lewis; Prabir K. Patra; Steven B. Warner; Shamal K. Mhetrev; MASSACHUSETTS UNIV DARTMOUTH DEPT OF TEXILE SCIENCES
|
| Nanocomposite fibers involve the concept of integrally dispensing nanosized particles of the second phase inorganic material into fiber forming polymers such as nylon or polyester. The material goal involves obtaining bi-phasic fibers with high mechanical stiffness and strength electrical conductivity and/or enhanced other features such as thermal stability, Thus far, the main difficulties toward achieving nanocomposite fibers are: (1) the inability of obtaining large quantities of nanoparticles in a pure, ... |
|
| Salt-Fog Accelerated Testing of Glass Fiber Reinforced Polymer Composites |
01 DEC 2002 |
53 pages |
| Authors:
Arsenio Caceres; Robert M. Jamond; Theresa A. Hoffard; L. J. Malvar; NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA
|
| The objective of this project was to determine the durability under accelerated salt-fog exposure of six commercially available composites. These composites included glass- reinforced vinylesters, polyesters, phenolics, and an epoxy. Durability was measured mainly in terms of the loss of elastic modulus and flexural strength after exposure. In order to accelerate aging, the specimens were subjected to temperatures of 95F (35C), 120F (49C), and 160F (71C) for one, two and ... |
|
| Lessons Learned in the Processing of Polycyanurate Resin Composites |
15 FEB 2002 |
27 pages |
| Authors:
R. J. Zaldivar; AEROSPACE CORP EL SEGUNDO CA LAB OPERATIONS
|
| Polycyanurate resins are a class of thermosetting polymers that have replaced epoxies as the matrix material of choice for structural composites used in space applications. Composites using a polycyanurate matrix are superior to those with epoxy matrices due to their increased toughness and dimensional stability, lower moisture absorption, reduced outgassing, and higher glass- transition temperatures. However, many of these superior properties are not always achieved due to difficulties that are ... |
|
| Strength and Durability of Glass Fiber Composites Treated With Multicomponent Sizing Formulations |
JAN 2002 |
38 pages |
| Authors:
Robert E. Jensen; Steven H. McKnight; Matthew J. Quesenberry; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| Commercial fiber-sizing packages have been developed to enhance the strength and moisture resistance of composite materials, which typically decreases ballistic performance. Potential sizing packages developed for Future Combat Systems will need to enhance ballistic response while maintaining the levels of durability currently benchmarked by existing commercial systems. For this research, pultruded vinyl ester/E-glass composites were manufactured in which the silane, film former resin, and surfactant reactivity were varied to mimic ... |
|
| Hull Material Selection for Replacement Patrol Boats - An Overview |
JAN 2002 |
|
| Authors:
Seref Aksu; Stuart Cannon; Craig Gardiner; Matthew Gudze; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION VICTORIA (AUSTRALIA) AERONAUTICAL AND MARITIME RESEARCH LAB
|
| This technical note considers the main characteristics of steel, aluminium alloys and glass fibre-reinforced composite materials in relation to the selection of primary structure for patrol boat type platforms. It is not intended to recommend or rank the suitability of candidate materials, but rather to note the main properties of each material and outline some practical considerations in relation to the construction, maintenance and military operation of patrol boats constructed ... |
|
| Ultra-Reliability Evaluation Based on Multi-Property Degradation Mechanisms |
2002 |
16 pages |
| Authors:
Toshio Nakamura; Raman P. Singh; STATE UNIV OF NEW YORK RESEARCH FOUNDATION AT STONY BROOK OFFICE OF SPONSOREDPROGRAMS
|
| The reliability of composite materials when exposed to multiple degradation environments was characterized. First, a new procedure based on inverse analysis and experimental measurements was established to characterize the transient moisture diffusion process in composites as a function of relative humidity and temperature. This procedure accounted for the heterogeneous microstructure in considerable detail, and was utilized to obtain the diffusivity and the maximum moisture content of the epoxy phase, and ... |
|
| The Durability Characterization of High Temperature Polymer Matrix - Carbon Fiber Composites for Future Air Force Applications |
30 OCT 2001 |
30 pages |
| Authors:
Roger J. Morgan; Jim Caruthers; Lawrence T. Drzal; Chuk Leung; Eugene Shin; MICHIGAN STATE UNIV EAST LANSING CONTRACT AND GRANT ADMINISTRATION
|
| Potential critical physical and chemical aging mechanisms in terms of damage initiation and propagation of bismaleimide, BMI and polymide, PI, - carbon fiber composites in future aerospace stress, time temperature moisture chemical service environments will be characterized. This characterization will be conducted on the molecular, microscopic and macroscopic structural levels in order to develop structural performance phase diagrams for mechanics model- structural design analyses and associated materials structural optimization at ... |
|
| Fracture of High Performance Fibers |
04 SEP 2001 |
7 pages |
| Authors:
Ali Sayir; CASE WESTERN RESERVE UNIV CLEVELAND OH
|
| An international workshop on Fracture of High Performance Fibers was held in November 2000 in Palma de Mallocra, Spain The performance of high temperature composites is dependent on understanding the mechanical properties of fibers. Many aspects of the controlling mechanisms of fiber fracture are unknown and this workshop brought together an interdisciplinary team of scientists and engineers from the United States and Europe to discuss the latest research in this ... |
|
| Nondestructive Evaluation (NDE) of Advanced Fiber Reinforced Polymer Composites |
JUL 2001 |
|
| Authors:
H. T. Yolken; George A. Matzkanin; Jill E. Bartel; NONDESTRUCTIVE TESTING INFORMATION ANALYSIS CENTER AUSTIN TX
|
| Fiber reinforced polymer composite materials continue to be used in a large number of applications ranging from aerospace to automotive, industrial and consumer products. The high stiffness-to-weight ratio, low electromagnetic reflectance, and the ability to embed sensors and actuators have made fiber reinforced composites an attractive alternative construction material for primary aircraft structures. In many other cases fiber reinforced polymer composite materials are being developed and used to replace metal ... |
|
| Method and System for Production of Fibrous Composite Prototypes Using Acoustic Manipulation in Stereolithography |
08 JUN 2001 |
22 pages |
| Authors:
Robert M. Koch; Robert Kuklinski; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A method for producing a three-dimensional object by stereolithography. A solid reinforcing material is mixed with the fluid medium so that at least a part of said solid reinforcing medium is located in the layer of the fluid medium between the top surface of the most recently formed lamina and the top surface of the fluid medium. An acoustic field is then established in the fluid medium such that this ... |
|
| Structural Technology and Analysis Program (STAP). Delivery Order 0017: Active Vibration Suppression Technology Buffet Load Alleviation (BLA) Program |
JUN 2001 |
93 pages |
| Authors:
Jay K. Burnham; BOEING CO ST LOUIS MO
|
| This final report documents the development of an experimental buffet load alleviation (BLA) system that utilizes distributed piezoelectric actuators in conjunction with a closed-loop rudder control system to reduce the structural dynamic response of fighter aircraft vertical tails to buffet loads. The BLA system was defined analytically with a detailed finite element model of the tail structure and piezoelectric actuators. Oscillatory aerodynamics were included along with a buffet forcing function ... |
|
| A Computational-Experimental Approach to Hierarchical Modeling of Damage and Failure in Non-Uniform Composite Materials |
2001 |
145 pages |
| Authors:
Somnath Ghosh; OHIO STATE UNIV COLUMBUS DEPT OF MECHANICAL ENGINEERING
|
| Progress has been made in advancing the state of the art in multiple- scale modeling of damage in composite materials, as delineated below. Interfacial Debonding Analysis in Multiple Fiber Reinforced Composites: Decohesion at multiple fiber interfaces of elastic fiber reinforced composites is modeled by the Voronoi cell finite element model (VCFEM). Interfacial debonding is accommodated by cohesive zone models and simulations are compared with results from experiments, performed using cruciform ... |
|
| Fracture Toughness Improvement of Composites Reinforced with Optimally Shaped Short Ductile Fibers |
2001 |
9 pages |
| Authors:
Robert C. Wetherhold; Abani K. Patra; STATE UNIV OF NEW YORK AT ALBANY RESEARCH FOUNDATION
|
| The fracture toughness of brittle matrix composites reinforced with ductile fibers has been greatly improved by shaping the fibers so that they fully contribute their plastic work to the fracture process. This has been accomplished by anchoring the fiber ends so that the largest possible fiber volume contributes to the toughness during pullout. A combined experimental and analytical program has shown that it is possible to organize fibers into shape ... |
|
Reports by Keyword(s)
*FIBER REINFORCED COMPOSITES
