| Durability of Composite Materials and Structures |
02-Nov-2009 |
15 pages |
| Authors:
Richard D Granata; William Hartt; Leif Carlsson; Hassan Mahfuz; Lawrence Drzal; Dayakar Penumadu; Clive Clayton; William Scott; FLORIDA ATLANTIC UNIV BOCA RATON
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 | This project focused on marine composites and sandwich structures with specific interests on the effects of moisture, seawater, hydrostatic pressure, and temperature on their durability and life prediction. One task revealed fiber changes that occur with nitric acid treatment promoting better engineering design of composite fiber matrix interface and interphase region. Comparative environmental exposures show that moisture absorption was along the F/M interface (wicking). A fracture mechanical model of single ... |
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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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| Comparison of Matrix Cracking in High Temperature and Lower Temperature PMCs from Cryogenic Exposure (Preprint) |
MAR 2007 |
11 pages |
| Authors:
Vernon T. Bechel; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH STRUCTURAL MATERIALS BRANCH/NONMETALLIC MATERIALS DIV
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| The behavior of a high temperature carbon/polyimide composite, T650/AFR-PE-4, in a cryogenic environment was studied. The results were compared to results from similar testing of a carbon/epoxy and a carbon/bismaleimide composite to begin to scale the difficulties involved with using high temperature polymer matrix composites (PMCs) in cryogen containers on launch vehicles. T650/AFR-PE-4 developed transverse cracks in all plies after fewer cycles than the carbon/bismaleimide (IM7/5250-4) when each was cycled ... |
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| Detection of Incipient Thermal Damage in Polymer Matrix Composites (Preprint) |
FEB 2007 |
10 pages |
| Authors:
Eric Lindgren; John Welter; Shamachary Sathish; Erik Ripberger; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| Polymer matrix composite mechanical properties have been shown to decrease significantly with the presence of thermal damage. For aerospace applications, this type of damage typically occurs as a result of exposure to elevated temperatures from localized heating, such as lightning strikes, exhaust wash, or improper maintenance/repair procedures. Mechanical testing has shown that this type of damage, known as incipient damage, is present even when no visible damage is observable and ... |
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| Detection of Incipient Thermal Damage in Polymer Matrix Composites (Preprint) |
DEC 2006 |
10 pages |
| Authors:
Eric Lindgren; John Welter; Shamachary Sathish; Erik Ripberger; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
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| Polymer matrix composite mechanical properties have been shown to decrease significantly with the presence of thermal damage. For aerospace applications, this type of damage typically occurs as a result of exposure to elevated temperatures from localized heating, such as lightning strikes, exhaust wash, or improper maintenance/repair procedures. Mechanical testing has shown that this type of damage, known as incipient damage, is present even when no visible damage is observable and ... |
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| Mechanisms of Matrix Metalloproteinase-Mediated p53 Regulation |
AUG 2006 |
28 pages |
| Authors:
Jimmie E. Fata; CALIFORNIA UNIV BERKELEY LAWRENCE BERKELEY LAB
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| Cell contraction and membrane blebbing are evolutionarily conserved events that occur during the execution phase of apoptosis. Several members of the TNF-ligand superfamily, which are associated with the promotion of a number of pathological processes, including inflammation and cancer are also capable of inducing membrane blebbing in some cell types. The majority of these ligands are transmembrane bound but can be shed from the cell surface through proteolytic processing where ... |
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| Multiscale Modeling for the Design of Autonomic Healing Structural Composite Materials (MEANS) |
25 JUN 2006 |
14 pages |
| Authors:
John Kieffer; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| We developed a suite of molecular-scale simulation tools, which includes all-atom MD simulations and coarse-graining procedures to interface with CVFE calculations at the continuum level. Polymerization reaction mechanisms and rates are identified in all-atom simulations. A first coarse-graining procedure consists of eliminating atoms that are unimportant for the mechanical properties of the structure. In a second coarse-graining procedure representation of monomers is simplified to spherically symmetric particles. This allows one ... |
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| Influence of Prepreg Microstructures on Structural Performance of Polymer Matrix Composites |
28 SEP 2005 |
69 pages |
| Authors:
Gregory P. Dillon; PENNSYLVANIA STATE UNIV UNIVERSITY PARK APPLIED RESEARCH LAB
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| This study provides methods by which composite prepreg materials can be characterized at the microscopic level. By applying established spatial tessellation schemes developed by Dirichlet, a means by which fiber packing may be conveniently characterized at a number of different length scales is provided. New micrographic preparation techniques are presented, that allow microscopic characterization of uncured prepreg material. This provides the starting point for an analysis that is intended to ... |
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| Thickness and Reinforcement Fiber Content Control in Composites by Vacuum-Assisted Resin Transfer Molding Fabrication Processes |
24 AUG 2005 |
38 pages |
| Authors:
William A. Spurgeon; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| This report presents two new vacuum-assisted resin transfer molding processes for fabricating polymer resin matrix composites. The processes enable the fabricator to control the volume percentage of reinforcement fiber from about 35% to 60%, depending on the weave style of the reinforcement. Control of the reinforcement content results in control of the thickness of the composite. The composites fabricated using these processes are also more uniform in fiber distribution than ... |
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| Mechanisms of Matrix Metalloproteinase-Mediated p53 Regulation |
AUG 2005 |
25 pages |
| Authors:
Jimmie Fata; CALIFORNIA UNIV BERKELEY LAWRENCE BERKELEY LAB
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| Cell contraction and membrane blebbing are evolutionarily conserved events that occur during the execution phase of apoptosis. Several members of the TNF-ligand superfamily, which are associated with the promotion of a number of pathological processes, including inflammation and cancer are also capable of inducing membrane blebbing in some cell types. Most of these ligands are transmembrane bound but can be shed from the cell surface through proteolytic processing where soluble ... |
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| Using Composites in Seismic Retrofit Applications |
20 APR 2005 |
201 pages |
| Authors:
V. M. Karbhari; AEROSPACE CORP EL SEGUNDO CA
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| This report was prepared to provide a comprehensive review of the state-of-the-art for using composite materials for seismic retrofit applications. The emphasis is on seismic retrofit of reinforced concrete columns. The report is presented in eleven chapters. Chapters 1-3 provide a basic introduction to composite materials, including discussions on the types of matrix and reinforcement materials, processing methods, and basic mechanics. Polymer matrix composites with continuous carbon or glass fibers ... |
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| Fatigue Behavior of a Functionally-Graded Titanium Matrix Composite |
MAR 2005 |
111 pages |
| Authors:
Scott R. Cunningham; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING AND MANAGEMENT
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| Functionally-graded Titanium Matrix Composites are an attempt to utilize the high-strength properties of a titanium matrix composite with a monolithic alloy having the more practical machining qualities. This work studied the mechanical characteristics of the joint region as a first step toward future evaluation of this material. The scope of this effort involved testing under monotonic tension and fatigue loading conditions. Mechanical properties and cyclic behavior were evaluated for the ... |
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| Curing of Composites: An Integrated Multiscale Process Description Toward Tailored Structures and Properties |
NOV 2004 |
92 pages |
| Authors:
Ranga Pitchumani; CONNECTICUT UNIV STORRS DEPT OF MECHANICAL ENGINEERING
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| The overall goal of the investigation was to develop a fundamental physical modeling of the complex thermal and mass transport mechanisms at the various scales (from the laminate to the microstructural and phase levels) that govern the interphase formation during cure. In particular, the goal of the University of Connecticut MEANS effort was to develop a comprehensive multiscale description of the cure process by addressing processing-related issues at the phase, ... |
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| Functional Polymer Matrix Fibers |
31 OCT 2004 |
5 pages |
| Authors:
Marcin K. Leonowicz; WARSAW TECHNICAL UNIV (POLAND)
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| This report results from a contract tasking Warsaw University of Technology as follows: The Grantee will investigate incorporation of magnetic and conductive nanoparticles into polymer fibers to maximize magnetic susceptibility, electrical conductivity, and physical flexibility. |
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| Multiscale Modeling for the Design of Autonomic Healing Structural Composite Materials |
31 AUG 2004 |
10 pages |
| Authors:
John Kieffer; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| This MEANS initiative research project consists of a collaborative effort between students, postdocs, and faculty at the University of Illinois and at the University of Michigan. The work involves the integration of length and time scale spanning computational methods of investigation into a suite of design tool for materials optimization. Concurrent experimental measurements serve to motivate and validate the simulation approaches. Specifically, the challenges posed by the design of autonomously ... |
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| Review of Soviet/Russian Literature on Residual Stress Development in Filament- Wound Polymer-Matrix Composites |
MAY 2004 |
41 pages |
| Authors:
Eric D. Wetzel; Scott R. White; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| This report provides a review of select Soviet and Russian (SIR) literature from the mid 1960s to the mid 199Os related to residual stresses in wound composite articles. Through a compilation of SIR review articles. a historical overview of the development of this SIR knowledge base is first provided. This overview is then followed by detailed compilations of the following topics: experimental measurement of residual stress development in wound composites. ... |
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| Modulation of Breast Cancer Cell Functions by Intracellular Signaling Through the Membrane Type-1 Matrix Metalloproteinase |
OCT 2002 |
28 pages |
| Authors:
Paolo Mignatti; NEW YORK UNIV NY SCHOOL OF MEDICINE
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| Membrane-type 1 matrix metalloproteinase (MT-MMPs), a member of the MMP family of proteinases, has been implicated in the invasive and metastatic potential of a variety of human malignancies, including mammary carcinoma Unlike the other members of the matrix metalloproteinase (MMP) family, which are secretory proteins, MT1-MMP is a transmembrane proteinase with the catalytic domain exposed on the cell surface and a short, 20 amino acid cytoplasmic domain. On the membrane ... |
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| Radiolabeled Matrix Metalloproteinase Inhibitors for Breast Cancer Therapy |
SEP 2002 |
12 pages |
| Authors:
Caroyln J. Anderson; WASHINGTON UNIV ST LOUIS MO
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| Matrix Metalloproteinases (MMPs), a family of over 20 types of enzymes, collectively are capable of degrading all the components of the extracellular matrix. MMP-2 and MMP-9 (also known as gelatinases) are specifically thought to play critical roles in tumor cell invasion and are frequently co-expressed in breast cancer. Cyclic peptides containing the sequence HWGF have been described as selective inhibitors of MMP-2 and MMP-9. We tested the hypothesis that gelatinase ... |
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| 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
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| 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 ... |
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| Scanning Tunneling Spectroscopy Study of Three-Dimensional Nanoscale Silicon and Platinum Assemblies in an Opal Matrix |
JUN 2001 |
4 pages |
| Authors:
C. Diaz-Guerra; V. G. Golubev; D. A. Kurdyukov; A. B. Pevtsov; J. Piqueras; UNIVERSIDAD COMPLUTENSE MADRID (SPAIN)DEPARTAMENTO DE FISICA DE MATERIALES
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| Regular systems of Si and Pt nanoclusters have been fabricated in a void sublattice of artificial opal. To incorporate Si into opal voids the thermal CVD technique is used. The samples are filled with Pt from a solution of PtCl(4) in ethanol to fabricate metal contacts to silicon. STM and STS are used to investigate the local electronic behavior of Pt-Si nanostructures. It is shown that Si and Pt are ... |
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| Investigation of Thick Bondline Adhesive Joints |
JUN 2001 |
104 pages |
| Authors:
J. S. Tomblin; C. Yang; P. Harter; WICHITA STATE UNIV KS
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| In recent years, the use of polymer matrix composite materials as primary structural components has risen, especially in the general aviation (GA) industry. The use of composites not only results in weight savings, but also reduces part counts, joining operations, and results in significant savings in assembly, storage, and inspection. However, joining of some integral parts is still required. GA aircraft industry also uses bonded joints with bondline thicknesses much ... |
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| Non-Polluting Composites Repair and Remanufacturing for Military Applications: Induction-Based Processing |
APR 2001 |
61 pages |
| Authors:
Bruce K. Fink; Nicholas B. Shevchenko; James M. Sands; Shridhar Yarlagadda; John W. Gillespie Jr; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| The development of induction-based processing of carbon-fiber (CF) thermoplastic-matrix composites and accelerated cure of thermosetting adhesives has the potential to provide nonautoclave processing technology for manufacturing and repair of polymer-matrix composites (PMCs). In this report, the results of recent tests demonstrating bonding of composites using commercial off-the-shelf thermal-cure adhesives that are heat cured via an induction field using an inductive susceptor are discussed. This method of cure utilizes heat generation ... |
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| 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
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| 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 ... |
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| Matrix-Assisted Synthesis of Palladium Nanocage and Nanowires |
2001 |
7 pages |
| Authors:
Jinwoo Cheon; Kyung-Bok Lee; Hongkyu Kang; S. J. Oh; H. -C. Ri; KOREA ADVANCED INST OF SCIENCE AND TECHNOLOGY TAEJON
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| Our study describes the synthesis of novel nanoscale Pd cage and wires whose sizes and shapes are templated by mesoporous matrices. The templates used are cubic phase MCM-48 and hexagonal phase C(sub n)MCM-41 (n = 16, and 22), SBA-15, which have pore diameters of approx.=3, approx.=3.8, approx.=4, approx.=7, and approx.=9 nm, respectively. For PdMCM-48, the Pd metal forms spherical domains (approx.=38 nm) consisting of three dimensionally interconnected into Pd arrays; ... |
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| The Mechanics and Mechanical Behavior of High-Temperature Intermetallic Matrix Composites |
30 JUN 2000 |
70 pages |
| Authors:
Ronald Gibala; Amit K. Ghosh; David J. Srolovitz; John W. Holmes; Noboru Kikuchi; MICHIGAN UNIV ANN ARBOR DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| This program has examined mechanics analyses and mechanical behavior of advanced intermetallic matrix composites based on the matrix materials MoSi2. Nb5Si3, NiAl, and TiAl, including Ti-based metal matrix composites. There has been a major focus on determination of strength of interfaces in composites under simple and complex loading configurations involving constrained deformation. Interface strength properties have been determined by use of novel experiments (e.g., ... |
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| Epoxy Functionalized Hyberbranched Polymer/Epoxy Blends |
DEC 1999 |
29 pages |
| Authors:
Thomas J. Mulkern; Donovan Harris; Alan R. Teets; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| In this preliminary study, two novel hyperbranched polymer (HBP)/ epoxy blends were evaluated to determine their efficiency as blend modifiers and tougheners in a brittle epoxy resin. The HBP is miscible in the epoxy and phase separates as cure progresses to form a two-phase system with a dispersed secondary phase of HBP/epoxy compatibilizers in a rigid epoxy matrix. There is no significant increase in the viscosity ... |
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| Non-Polluting Composites Repair and Remanufacturing for Military Applications: An Environmental and Cost-Savings Analysis |
DEC 1999 |
103 pages |
| Authors:
Bruce K. Fink; Steven H. McKnight; Crystal H. Newton; John W. Gillespie Jr.; Giuseppe R. Palmese; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
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| Polymer-matrix composite material and structural adhesive repair and manufacturing have significant environmental costs for Department of Defense (DOD) use. 'The principal issues for reducing environmental costs are (1) reducing hazardous waste by eliminating shelf-life limitations; (2) reducing nitrogen oxides (NOx) by replacing global heating of the part with localized heating; (3) reducing volatile organic compound (VOC) emissions by accelerated curing and containment; and (4) ... |
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| Laminated Matrix Composites - A New Class of Materials |
28 OCT 1999 |
51 pages |
| Authors:
W. J. Lackey; Elliot Pickering; Harry King; Stephen Crain; Mark Renier; GEORGIA INST OF TECH ATLANTA SCHOOL OFMECHANICAL ENGINEERING
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| A new type of composite, which consists of a reinforcement phase plus a matrix composed of many alternate thin layers of two different materials, has been prepared. CVI appears to be an appropriate process for the fabrication of this class of materials. We have successfully fabricated such a composite using the forced flow-thermal gradient CVI process. A carbon 2-D cloth preform was infiltrated with alternate layers ... |
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| Materials for High Temperature Spectral Hole Burning Optical Storage |
08 OCT 1999 |
10 pages |
| Authors:
R. R. Alfano; A. A. Gorokhovsky; CITY COLL NEW YORK
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| The optical properties of four Tm(3+) ion - organic ligand chelate complexes in a poly(methyl methacrylate) matrix were studied. These materials are interesting for potential applications of optical hole-burning frequency and time-domain storage and processing. Optical absorption, steady state and time- resolved photoluminescence, and spectral hole-burning at the transition between 3-H6 (1) and 3-H4 (1) crystal-field levels were studied at temperatures between 1.4 and 300 ... |
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| Biorepellent Matrix Coating |
20 JUL 1999 |
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| Authors:
David M. Bullat; Niraj Vasishtha; DEPARTMENT OF THE NAVY WASHINGTON DC
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 | A biorepellent matrix structure comprises a resin and first and second microcapsules suspended in the resin. The first and second microcapsules each includes a first shell and a second shell respectively, containing a biorepellent material that is released upon penetration of any of the first and second shells, as for example, by a biological organism. The biorepellent material, such as capsaicin diffuses through the first and second shells at different ... |
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| Optimization of Textile Composite Toughness |
07 JUL 1999 |
249 pages |
| Authors:
Brian Cox; ROCKWELL INTERNATIONAL CORP THOUSAND OAKS CA SCIENCE CENTER
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| We have designed, made, and tested novel composites, including composites of chains, braided composites, and knitted composites, which show exceptionally high energy absorption under tensile loading. Values per unit volume range up to 60 MJ/cu m and per unit mass up to 25 J/g. Analytical micromechanical models have led to design rules, which indicate that energy absorption per unit volume of up to 250-300 MJ/cu ... |
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| Progressive Failure Analysis of Composite Panels |
MAR 1999 |
187 pages |
| Authors:
Stephen M. Spottswood; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
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| The objective of this research was to determine the physical response, including material failure, of a curved composite panel designed to resist transverse loading. The cause of the material failure, in the form of delamination, fiber and/or matrix failure, was determined through various criterion based on non-linear movement using a finite element analysis technique. Data generated both with and without the addition of progressive failure criteria, was compared with previously ... |
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| Characterization of Critical Fundamental Aging Mechanisms of High Temperature Polymer Matrix Composites |
SEP 1998 |
28 pages |
| Authors:
Roger J. Morgan; E. E. Shin; Lawrence T. Drzal; Andre Lee; MICHIGAN STATE UNIV EAST LANSING COMPOSITE MATERIALS STRUCTURES CENTER
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| This program investigated durability and potential critical fundamental aging mechanisms of the high temperature polymer matrix carbon fiber composites, especially crosslinked bismaleimide(BMI) thermosets and thermoplastic polyimide(PI) for the future applications in commercial and military aircraft. The studies involved combined stress, temperature, thermal cycling or thermal spike, moisture, time and oxygen service environment exposure which could lead to complex synergistic environmental-induced degradation mechanisms of composite ... |
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| Development and Testing of an Interface for Real-Time Visualization of Resin Flow in Composites |
SEP 1998 |
44 pages |
| Authors:
William Green; Dale Shires; Shawn Walsh; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The manufacture of polymer composite materials has benefited greatly from the development of computer-based simulation tools and sensor-based instrumentation. The present research offers a unique and powerful interface for collecting, integrating, analyzing, and rendering critical data related to a dynamic composite manufacturing process. These operations are executed in real time over the internet, permitting unprecedented flexibility and speed in deploying and using the manufacturing "tools." ... |
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| Non-Polluting Composites Repair and Remanufacturing for Military Applications: An Environmental and Cost-Savings Analysis |
SEP 1998 |
62 pages |
| Authors:
Crystal H. Newton; Bruce K. Fink; Steven H. McKnight; John W. Gillespie Jr.; Giuseppe R. Palmese; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Polymer-matrix composite material and structural adhesive repair and manufacturing have significant environmental cost. These costs are documented based on current and anticipated future Department of Defense use of these materials. This special report first establishes an environmental baseline by identifying the hazardous materials encountered during composite repair and manufacturing operations and presents conservative estimates of usage and waste production. The principal issues for reducing ... |
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| Accelerated Environmental Testing of Composite Materials |
APR 1998 |
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| Authors:
Roger Vodicka; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION CANBERRA (AUSTRALIA)
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| Composite materials are found to lose mechanical on exposure to aircraft operating environments. This is mainly due to absorption of moisture from humid air by the matrix material. Composite materials are extensively used by the RAAF for both major structural components on the F/A-18 and for bonded repairs and doublers. The performance of these materials under long-term environmental exposure is an important aspect of both ... |
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| Failure Modes in Brittle Matrix Composites (BMC) |
APR 98 |
11 pages |
| Authors:
Nicholas J. Pagano; G. P. Tandon; R. Y. Kim; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE
|
| The objective of this program was to derive theoretical models to predict micromechanical fracture events in BMC. Incorporate the micromechanical models into composite laminate theory. Provide experimental confirmation and characterization approaches. Delineate interface interphase effects on BMC response. This is a bibliography of the publications generated by this program. |
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| Synthesis, Interface and Properties of Nanodispersed Aluminum |
30 JAN 1998 |
57 pages |
| Authors:
K. Chattopadhyay; ASIAN OFFICE OF AEROSPACE RESEARCH AND DEVELOPMENT APO AP 96337-0007
|
| The work on synthesis and study of phase transformation of the soft phase dispersed in aluminum based matrices was obtained. This research successfully synthesized nanometric dispersions of bismuth (Bi) in a glassy Aluminum-Iron-Silicon (Al-Fe-Si) matrix by using rapid solidification technique. The Bi melt is immiscible with the ternary melt of Al-Fe-Si and phase separates. Thus quenching rapidly through the miscibility gap has enabled to obtain nanometric dispersions of Bi Particles ... |
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| Environmental Interactions and Fracture in Polymer-Matrix Composites |
DEC 97 |
16 pages |
| Authors:
Roger C. Newman; Stuart B. Lyon; MANCHESTER UNIV (UNITED KINGDOM)
|
| This project was concerned with the link between transport and fracture in composite materials with emphasis on degradation of properties on aqueous exposure. The dependence of transport and fracture on volume fraction of a particulate filler was considered in terms of the percolation properties of the connected and unconnected particles. This report describes: validation of the percolation approach; mechanical properties ad effect of water absorption; electrical and gravimetric measurements; and ... |
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| Cure Monitoring Techniques Using Embedded Sensors |
SEP 97 |
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| Authors:
Roger Vodicka; DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION CANBERRA (AUSTRALIA)
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| Assessing the exact state of cure of thermosetting polymer composite components using embedded sensors can allow the user to precisely control the cure cycle in order to achieve optimum cure. This is desirable in a field repair situation where a non-optimum cure cycle may have to be adopted. At present a wide variety of options are available. However, to be practical for bonded composite repair, especially field repair, it is ... |
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| Mechanics of Brittle-Matrix Composites |
AUG 1997 |
58 pages |
| Authors:
Ran Y. Kim; DAYTON UNIV OH RESEARCH INST
|
| Model brittle matrix composites (SiC fibers and borosilicate glass) demonstrated that good matrix cracking stress is achievable only when a good matrix interfacial bond exists. Improvement in this matrix cracking stress can be seen with increasing fiber volume and lowered radial residual compressive stress. The ability to measure the fiber-matrix normal interfacial strength in a composite was demonstrated using a model system in a cruciform sample geometry. An analytical model ... |
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| Assessment of the DARPA Affordable Polymer Matrix Composites Programs |
JUL 97 |
|
| Authors:
Lisa C. Veitch; INSTITUTE FOR DEFENSE ANALYSES ALEXANDRIA VA
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| This document is a technical assessment of the Defense Advanced Research Projects Agency (DARPA) Affordable Polymer Matrix Composite (PMC) program. The projects under this program were initiated to develop and demonstrate technologies that would reduce the acquisition costs of composites for high performance air vehicles and other platforms by 30+ percent, develop a composite structure equal to or lower than the cost of a metallic structure for transports and other ... |
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| Environmental Effects on Polymer-Matrix Composites |
JUN 1997 |
56 pages |
| Authors:
C. W. Lee; B. P. Rice; K. E. Thorp; DAYTON UNIV OH RESEARCH INST
|
| A variety of environmental factors can influence the performance of advanced polymers and composites. In particular, exposure to a combination of moisture and elevated temperature can significantly alter properties. The extent of chemical and physical changes is a function of exposure time and the temperature and humidity of the environment. This work discusses the effects of chemical and physical aging of AFR700B, a high-temperature addition polyimide ... |
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| Method of Producing a Film Coating by Matrix Assisted Pulsed Laser Deposition |
28 MAY 1997 |
28 pages |
| Authors:
Robert A. McGill; Douglas B. Chrisey; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A film of a coating material is produced on a substrate by a pulsed laser deposition method in which the material that forms the coating material is first combined with a matrix material to form a target. The target is then exposed to a source of laser energy to desorb the matrix material from the target and lift the coating material from the surface of the target. The target and ... |
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| The Micromechanics of Deformation and Failure in Metal-Matrix Composites |
MAY 97 |
6 pages |
| Authors:
Alan Needleman; BROWN UNIV PROVIDENCE RI DIV OF ENGINEERING
|
| Metals reinforced with ceramic fibers or particulates are promising materials for use in new generations of aerospace structures, propulsion devices and energy conversion systems. Furthermore, the controllability of many of these variables opens up the possibility of engineering materials for specific applications, if the effects of alterations in microstructure can be predicted. However, metal-matrix composites often have low ductility and low fracture toughness. An improved understanding of the basic deformation ... |
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| Marking of Materials Using Luminescent and Optically Stimulable Luminescent Glasses |
29 APR 1997 |
26 pages |
| Authors:
Huston; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| Objects are marked for identification by a luminescent label including an optically stimulable glass having trapping centers and luminescence centers. The objects are marked by exposing the luminescent label to a radiation flux to populate metastable trapping centers in the luminescent label, The labels are read by exposing the label to a second radiation flux of optical radiation, to stimulate the release of trapped charges, causing the label to luminescence. ... |
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| Load Transfer Characteristics and Residual Stresses in Composite Material Systems |
FEB 97 |
67 pages |
| Authors:
E. S. Folias; UTAH UNIV SALT LAKE CITY DEPT OF MATHEMATICS
|
| In this study, the load transfer characteristics of a broken fiber are investigated. The problem consists of a cylindrical fiber that is embedded into a matrix material. The fiber axis is assumed to coincide with the z-axis and a crack is assumed to be present on the plane z =0 and for r < a. Far away from the crack, the fiber is subjected to uniform external load of sigma ... |
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| The Evaluation of Thermally Induced Damage in Polymer Matrix Composites via a Design of Experiments Approach |
JAN 97 |
58 pages |
| Authors:
Mark D. Kistner; Ronald J. Kuhbander; Daniel B. McCray; DAYTON UNIV OH RESEARCH INST
|
| As of the date of this report overheat damage is an area of concern for the supportability of polymeric matrix composites, since a significant amount of strength is lost, up to 30% in shear, before this a damage is detectable by standard ultrasonic inspections techniques. This report takes the approach of using a design of experiments to determine which factors and interactions significantly affect the heat damage behavior of polymeric ... |
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| Glass Matrix Doped with Activated Luminescent Nanocrystalline Particles. |
17 DEC 1996 |
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| Authors:
Alan L. Huston; Brian L. Justus; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A luminescent glass includes nanocrystalline semiconductor particles, such as ZnS nanocrystals, and an activator, such as copper, for the particles. The glass is made by depositing the nanocrystalline semiconductor particles and the activator within a porous glass matrix, such as 7930 Vycor(TM) and then thermally activating the glass. The porous glass matrix may be at least partially consolidated or may be allowed to remain porous. The nanometer particle size permits ... |
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| Adaptive and Parallel Computational Techniques in Materials Science |
09 AUG 96 |
17 pages |
| Authors:
Joseph E. Flaherty; RENSSELAER POLYTECHNIC INST TROY NY
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| We developed mathematical models for problems involving the fabrication of ceramic- matrix composites, the coating of ceramic fibers, and the oxidation of ceramic-matrix composites. To solve these models, we developed an adaptive and parallel computational framework for the finite element and finite volume solution of partial differential equations. The parallel adaptive framework handles mesh generation, refinement, and coarsening; dynamic load balancing; distributed database management; interprocessor communications; data migration; time integration; ... |
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