| Comparison of Slip Cast to Hot Pressed Boron Carbide |
Feb-2009 |
14 pages |
| Authors:
T Sano; E S Chin; B Paliwal; M W Chen; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
 | To meet the possible increase in future demand for armor materials, an increase in the throughput during manufacturing is necessary. One possibility is the use of the slip casting and sintering technique to form ceramic armor compacts as an alternative to current hot pressing techniques. Dynamic uniaxial compression tests with the Kolsky bar were conducted on two types of slip cast boron carbide, and compared with results from the standard ... |
|
| Z-Pin Stubble Technology Advanced Research (ZSTAR) |
APR 2008 |
60 pages |
| Authors:
Stephen B. Clay; Amanda K. Pommer; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH ADVANCED STRUCTURAL CONCEPTS BRANCH
|
| Z-pins are small-diameter carbon rods that are ultrasonically inserted through composite laminates in the z-direction to provide extra resistance to crack growth and delamination. They are normally inserted through co-cured composites, but this report presents an experimental study on a new z-pin stubble manufacturing technique that is compatible with the co-bonding process. Early researchers were limited to an exposed stubble height of 0.030 inch, which would not provide all of ... |
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| Military Bridging and Maneuver Warfare: Deficiencies and the Way Ahead |
19-Feb-2008 |
12 pages |
| Authors:
J L Wagner; MARINE CORPS COMMAND AND STAFF COLL QUANTICO VA
|
| The United States Marine Corps' concept of expeditionary maneuver warfare focuses on the ability to take action to generate and exploit some kind of advantage over the enemy as a means of accomplishing our objectives as effectively as possible. This concept has driven the Marine Corps Systems Command to procure equipment that can be rapidly and efficiently employed to generate speed and tempo. Inherent in maneuver warfare is the need ... |
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| Multifunctional Structural Composite Batteries |
SEP 2007 |
18 pages |
| Authors:
J. F. Snyder; R. H. Carter; E. L. Wong; P. A. Nguyen; K. Xu; E. H. Ngo; E. D. Wetzel; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD WEAPONS AND MATERIALS RESEARCH DIRECTORATE
|
| We are developing structural polymeric composites that both carry structural loads and store electrochemical energy. These multifunctional batteries could replace inert structural components while providing supplementary power for light load applications. If designed with sufficient structural and energy efficiency, these materials could also enable significant system-level weight reductions. To enable this concept, loadbearing properties must be engineered into the battery packaging, electrolyte, and/or electrodes. Previous examples of structural batteries have ... |
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| Effect of Ply Thickness on the Damage Development in Composite Laminates (Preprint) |
FEB 2006 |
13 pages |
| Authors:
Ran Y. Kim; Sangwook Sihn; Steven L. Donaldson; DAYTON UNIV RESEARCH INST (UDRI) OH ENERGY AND ENVIRONMENTAL ENGINEERING DIV
|
| This paper describes the experimental investigation on the effect of ply thickness on the first ply failure, delamination, and the subsequent final failure of graphite/epoxy composite laminates. The laminates considered in this paper are a cross-ply and two quasi-isotropic laminates containing thin plies in the desired interface. The onset of the first ply failure and delamination, and the stress-free temperature are experimentally determined. The experimental results for ply crack and ... |
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| Design Engineering and Support Program (DESP). Delivery Order RZ16: Effects On Mechanical Properties From Laser Paint Stripping |
FEB 2005 |
63 pages |
| Authors:
DAYTON UNIV OH RESEARCH INST
|
|
| Strength Degradation of Filament-Wound Graphite/Epoxy Tubes Due to Either Impact Damage or Fabrication Defects |
01 AUG 2004 |
17 pages |
| Authors:
D. J. Chang; H. A. Katzman; AEROSPACE CORP EL SEGUNDO CA
|
| Two test series were conducted to assess the strength degradation of filament-wound graphite/epoxy tubes caused by impact damage or fabrication defects. The defects were either helical wrinkles or a hoop wrinkle inside the tube walls. The baseline tube configuration had a nine-ply (+10 deg, -10 deg, 90 deg)3 lay-up, with the exception of one tube having a (+15 deg, -l5 deg, 90 deg, 90 deg)3 stacking sequence. The latter lay-up ... |
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| Using High-Fidelity Analysis Methods and Experimental Results to Account for the Effects of Imperfections on the Buckling Response of Composite Shell Structures |
27 AUG 2003 |
14 pages |
| Authors:
James H. Starnes Jr.; Mark W. Hillburger; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CENTER
|
| The results of an experimental and analytical study of the effects of initial imperfections on the buckling response of unstiffened thin-walled compression-loaded graphite-epoxy cylindrical shells are presented. The analytical results include the effects of traditional and nontraditional initial imperfections and uncertainties in the values of selected shell parameters on the buckling loads of the shells. The nonlinear structural analysis results correlate very well with the experimental results. The high-fidelity nonlinear ... |
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| Air Force Fast Center for Lightweight Structural Materials and Processing |
14 AUG 2003 |
106 pages |
| Authors:
Paul O. Biney; Jianren Zhou; Laura Carson; PRAIRIE VIEW A AND M UNIV TX
|
| The sixth year of the FAST Center at Prairie View A&M University was mainly devoted to the continuation of research in polymer processing and characterization, and mechanical and microstructural characterization, and a study of environmental effects on the properties of composites. |
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| Assessment of a Crack Tip Element-Based Approach for Predicting Delamination Growth in Interlayer-Toughened Composite Skin-Stringer Panels |
DEC 2002 |
102 pages |
| Authors:
L. M. Rao; B. D. Davidson; SYRACUSE UNIV NY DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| A crack tip element approach to predict delamination growth is reviewed and then used to predict delamination growth in two stiffened-skin geometries that are typical of aircraft configurations. Predictions by this approach are then compared with experimental results. Test specimens were fabricated from T800H/3900-2, which is a graphite/epoxy material system toughened by a thermoplastic interlayer. Experiments were then performed, and predictions were compared to the observed results. Predictions that incorporated ... |
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| Metal Matrix Composites for Ordnance Applications. NDIA Firepower Symposium Held in U. S. Army Research Laboratory, Aberdeen Proving Ground, MD on 20 Jun 2001 |
20 JUN 2001 |
|
| Authors:
Christopher Hoppel; John H. Beatty; Jonathan S. Montgomery; James M. Bender; Travis A. Bogetti; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
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| The Effect of Loading Parameters on Fatigue of Composite Laminates: Part V |
JUN 2001 |
58 pages |
| Authors:
H. T. Hahn; S. W. Choi; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| This report is the fifth in a series of reports on the damage growth of notched and visible impact-damaged AS4/3501-6 graphite/epoxy quasi-isotropic laminates under long-term mechanical fatigue loading. The effects of load type, load level, load sequence, and spectrum modification are evaluated in this study. X-ray radiography is taken of the test specimens to monitor the fatigue damage, which are in the form of splitting and delamination around the center ... |
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| Polymer Matrix Composite (PMC) Damage Tolerance and Repair Technology |
APR 2001 |
27 pages |
| Authors:
Ran Y. Kim; DAYTON UNIV OH RESEARCH INST
|
| The application of composites in space structures such as reusable launch vehicles requires a detailed understanding of their mechanical behavior and damage resistance in the service environment. Experimental and analytical studies were conducted on IM7/977-3, a graphite-toughened epoxy, to characterize the influence of cryogenic service temperatures on the strength, modulus, and fracture of this material system, and on transverse crack initiation in cross- ply laminates at 23, -129, and -196 ... |
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| The Effect of Loading Parameters on Fatigue of Composite Laminates: Part IV Information Systems |
DEC 2000 |
77 pages |
| Authors:
H. T. Hahn; Ozgur Turkgenc; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| Damage tolerance, damage resistance and durability assessments of aircraft composite structures are essential components of certification. The certification procedure requires lengthy experimental validation of those assessments, although much research has been conducted to understand the behavior of polymer matrix composites under service conditions. A fair amount of data is available together with a number of analytical models in these areas of research. However, because of the vast number of parameters ... |
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| Preliminary Report on Super Composite Beam and Split Cylinder Experiments |
JUL 2000 |
59 pages |
| Authors:
P. Y. Tang; J. S. Burns; SPACE AND NAVAL WARFARE SYSTEMS CENTER SAN DIEGO CA
|
| These experiments had two main objectives: (1) explore and demonstrate whether the bending- extension (b-e) coupling effect of graphite/ epoxy two-layered cross-ply laminate has the potential to substantially improve (e.g., reduce fundamental natural frequencies of) low-frequency, wall-driven composite projectors (such as the slotted cylinder projector), and (2) provide experimental data to confirm theoretical predictions (made with previously derived analytical solutions) on b-e coupled composite beams with simple supports. Vibration tests ... |
|
| Airway Reactivity Response to Advanced Composite Material (ACM) combustion Atmospheres: B2-ACM |
MAR 2000 |
83 pages |
| Authors:
Edgar C. Kimmel; James E. Reboulet; David L. Courson; Gregory S. Whitehead; Kenneth R. Still; NAVAL HEALTH RESEARCH CENTER WRIGHT-PATTERSON AFB OH TOXICOLOGY DETACHMENT
|
| Exposure for 30 minutes to diluted smoke from pyrolysis of advanced composite material used in the construction of the B2 bomber (B2-ACM) caused an airway reactivity (AR) response in naive guinea pigs reminiscent of a human asthmatic episode. Animals exposed to diluted smoke from pyrolysis of 5, 10 and 100 grams of B2-ACM showed changes in a number of parameters characterizing ventilation, breathing pattern, and ... |
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| Full-Scale DELTA GEM MPS Demonstration - May 11-12, 1999 AFRL/EAFB rocket Laboratory |
15 NOV 1999 |
20 pages |
| Authors:
J. Osborn; B. Brown; S. Amimoto; E. Fournier; AEROSPACE CORP EL SEGUNDO CA TECHNOLOGY OPERATIONS
|
| A prototype Multiparameter Sensor System (MPS) is described for impact detection and environmental condition monitoring of graphite epoxy composite structures. This system is applied to a full-scale inert Delta-II solid rocket Graphite Epoxy Motor (GEM) casing. Microelectro-mechanical (MEMS) sensors are used in this demonstration, including those for 3-axis acceleration, temperature, pressure and humidity. All sensor measurements are made within a single package mounted at the ... |
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| The Effect of Loading Parameters on Fatigue of Composite Laminates: Part 3 |
JUN 1999 |
69 pages |
| Authors:
H. T. Han; Milan Mitrovic; Ozgur Turkgenc; CALIFORNIA UNIV LOS ANGELES DEPT OF MECHANICAL AEROSPACE AND NUCLEAR ENGINEERING
|
| The long-term mechanical fatigue of quasi-isotropic graphite/epoxy laminates was investigated to determine the influence of loading parameters on impact-induced delamination growth during constant-amplitude and spectrum fatigue loading. Based on the test results, recommendations for fatigue design of composite laminates in the presence of barely visible impact damage (BVID) are suggested. |
|
| Modeling of Pulsed Thermography in Anisotropic Media |
07 MAY 1999 |
20 pages |
| Authors:
I. Perez; P. Kulowitch; W. Davis; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
|
| Thermography is increasingly being used as an NDE tool to detect damage (corrosion, delamination, water incursion) in materials. Many empirical results have been collected over the years that allow the operator to get a "feel" for the extent of the problem. No simple models exist that provide quantitative results. Finite element analysis is done but is laborious and does not provide simple relationships which can be utilized for quantitative analysis ... |
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| Spline Variational Theory for Composite Bolted Joints |
JAN 1999 |
52 pages |
| Authors:
E. Iarve; DAYTON UNIV OH RESEARCH INST
|
| The hybrid numerical approximation model for predicting stresses and strains in open-hole composites was refined. The model was also expanded to include singular full-field stress analysis of multi-interface composites under mechanical, thermal and bearing loads. The rigid fastener hole problem was also examined. This hybrid model, using spline variational theory and Reissner's variational principle, provides accurate solutions in the vicinity of the singularity. Convergence with coarse subdivisions was observed if ... |
|
| Mechanical Vibration Testing Results of Acoustic Test Panels |
DEC 1998 |
17 pages |
| Authors:
Colin P. Ratcliffe; Roger M. Crane; NAVAL SURFACE WARFARE CENTER CARDEROCK DIV BETHESDA MD
|
| This report describes the mechanical vibration testing of two graphite reinforced composite plates. The plates were tested in a free-free boundary condition up to a frequency of approximately 6 kHz. The plates were designed to assess two different damping treatments. They consisted of a 1.37 inch thick carbon epoxy structural section with a 0.13 in thick region on one side for each treatment. One plate used a conventional constrained layer ... |
|
| Core Programs of High-Performance Composite Materials |
DEC 1998 |
159 pages |
| Authors:
A. Crasto; D. Anderson; R. Esterline; K. Han; C. Hill; DAYTON UNIV OH RESEARCH INST
|
| Evaluation of composites and components continued from the previous contract. Materials used to RTM carbon-carbon preforms were evaluated. RDS data analysis software was written and modulated DSC evaluated as an analysis tool. Bridge rehabilitation successfully tested a new embedded rod technique. The measured CTE changes of composites were found to correlate with cracking densities. Damage during loading around holes in composites consisted of longitudinal cracks and delaminations. Transverse cracking was ... |
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| A Predictive Methodology for Delamination Growth in Laminated Composites Part I: Theoretical Development and Preliminary Experimental Results |
APR 1998 |
50 pages |
| Authors:
Barry D. Davidson; SYRACUSE UNIV NY DEPT OF MECHANICAL AND AEROSPACE ENGINEERING
|
| A methodology is presented for the prediction of delamination growth in laminated structures. The methodology is aimed at overcoming computational difficulties in the determination of energy release rate and mode mix. It also addresses the issue that many laminated composites exhibit large-scale crack tip damage zones and, as such, a singular field-based mode mix decomposition may not accurately account for the dependence of toughness on the loading. In the methodology, ... |
|
| Design and Analysis of a Pressurized Composite Fuel Tank |
25 MAR 1998 |
|
| Authors:
Andrew L. Martin; AIR FORCE INST OF TECH WRIGHT-PATTERSONAFB OH
|
 | An investigation works towards obtaining a lightweight, cost- effective pressurized fuel tank for a hybrid sounding rocket with a capacity of 20 kg of either Nitrous Oxide or Hydrogen Peroxide. Trade studies result in analyzing a graphite epoxy prepreg composite tank with unidirectional lamina designed for a burst pressure of 2000 psi. The analysis resulted in a pressure vessel in the shape of a cylinder ... |
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| Fiber Finishes for Improving Galvanic Resistance of Imide-Based Composites |
12 FEB 98 |
58 pages |
| Authors:
Ronald E. Allred; Richard E. Jensen; Thomas A. Donnellan; Theotis Williams Jr; ADHERENT TECHNOLOGIES ALBUQUERQUE NM
|
| The objective of this program is the development and demonstration of galvanic corrosion resistant carbon/ BMI composites through the use of reactive finishes to form coatings that isolate the carbon fibers from the BMI matrix. A family of novel reactive coupling agents was formulated into based phenolic finishes for carbon and graphite fibers that will subsequently react with the fiber and matrix resin during processing to ... |
|
| Spline Variational Theory for Composite Bolted Joints |
JAN 1998 |
56 pages |
| Authors:
E. Iarve; R. Y. Kim; DAYTON UNIV OH RESEARCH INST
|
| A hybrid approximation model for predicting stresses and strains in open-hole composites was developed. This model is based on combined asymptotic and spline approximation stress functions and spline approximation displacement functions which provide accurate stress fields in the vicinity of the ply interface and the hole edge in a multilayered composite laminate. This hybrid model, using spline variational theory and Reissner's variational principle, provides ... |
|
| Modeling of Pulsed Thermography in Anisotropic Media |
1998 |
23 pages |
| Authors:
Ignacio Perez; Rachel Santos; Paul Kulowitch; Steven Shepard; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
|
| A simple thermographic model has been developed that accurately describes the surface temperature response of an aluminum panel with flat bottom holes of different depths and diameters to a short heat pulse. This model assumed that a thin layer of material at the surface is instantaneously heated by the pulse, and that subsequent cooling of the surface is due to diffusion of the deposited energy into ... |
|
| Composite Failure Analysis Handbook Update 1 |
AUG 97 |
264 pages |
| Authors:
Gregory M. Walker; BOEING DEFENSE AND SPACE GROUP SEATTLE WA MATERIALS PROCESSES AND PHYSICS TE CHNOLOGY DIV
|
| This report supplements the data and analyses provided in the previously released 'Composite Failure Analysis Handbook,' WL-TR-91-4032/DOT/ FAA/CT-91/23. It contains fractograhic data from failed composite test specimens as well as ease histories of failed composite structure. Fractographic data from statically loaded test specimens are presented for carbon/epoxy (AS4/3501-6), carbon/ pseudothermoplastic (AS4/KIII), carbon/polyimide (AS4/PMR-15), carbon/ thermoplastic (AS4/PEEK), carbon/bismaleimide (AS4/MR-54-4), and carbon and glass low-temperature curing epoxy, (HTA 5131-12K/Rutapox L-20/SL and EC ... |
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| Characterization of the Dynamic Response of Thick Composite Structures |
JUN 97 |
6 pages |
| Authors:
MAINE UNIV AT ORONO
|
| The objective for this research remains at contributing to the understanding of the fundamental mechanisms which determine the response of thick composite structures to time dependent loading. The following specific objectives were originally proposed and, with some modification, continue to form the basis for the research plan: (1) Postulate the primary micromechanical attributes in the range of relatively small strain which are expected to directly affect frequencies, mode shapes, participation ... |
|
| Proceedings of the Annual Mechanics of Composites Review (15th) |
APR 97 |
312 pages |
| Authors:
AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OH NONMETALLIC MATERIALS LAB
|
| This report contains the basic unedited vu-graphs of the presentations at the 'Mechanics' of Composites Review' sponsored jointly by the Non-metallic Materials Division of the Air Force Materials Laboratory, the Structures Division of the Air Force Flight Dynamics Laboratory and the Directorate of Aerospace Sciences of the Air Force Office of Scientific Research. The presentations cover current in-house and contract programs under the sponsorship of these three organizations. |
|
| Proceedings of the Annual Mechanics of Composites Review (16th) |
APR 97 |
313 pages |
| Authors:
AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OH NONMETALLIC MATERIALS LAB
|
| This report contains the basic unedited vu-graphs of the presentations at the 'Mechanics' of Composites Review' sponsored jointly by the Non-metallic Materials Division of the Air Force Materials Laboratory, the Structures Division of the Air Force Flight Dynamics Laboratory and the Directorate of Aerospace Sciences of the Air Force Office of Scientific Research. The presentations cover current in-house and contract programs under the sponsorship of these three organizations. |
|
| Advanced Certification Methodology for Composite Structures |
APR 97 |
167 pages |
| Authors:
H. P. Kan; R. Cordero; R. S. Whitehead; NORTHROP CORP HAWTHORNE CA
|
| An improved certification methodology for composite structures was developed. The methodology permits certification of bonded and concurred composite structures with the same level of confidence as bolted structures. This methodology also ensures that the threat of in service low velocity impact is adequately addressed. The methodology was demonstrated on actual composite aircraft structures to evaluate the damage tolerance capability of these structures. The F/A-18A upper wing skin was used for ... |
|
| Proceedings of the Annual Mechanics of Composites Review (14th) |
APR 97 |
172 pages |
| Authors:
AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OH NONMETALLIC MATERIALS LAB
|
| This report contains the basic unedited vu-graphs of the presentations at the 'Mechanics' of Composites Review' sponsored jointly by the Non-metallic Materials Division of the Air Force Materials Laboratory, the Structures Division of the Air Force Flight Dynamics Laboratory and the Directorate of Aerospace Sciences of the Air Force Office of Scientific Research. The presentations cover current in-house and contract programs under the sponsorship of these three organizations. |
|
| Proceedings of the Annual Mechanics of Composites Review (13th) |
APR 97 |
215 pages |
| Authors:
AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OH NONMETALLIC MATERIALS LAB
|
| This report contains the basic unedited vu-graphs of the presentations at the 'Mechanics' of Composites Review' sponsored jointly by the Non-metallic Materials Division of the Air Force Materials Laboratory, the Structures Division of the Air Force Flight Dynamics Laboratory and the Directorate of Aerospace Sciences of the Air Force Office of Scientific Research. The presentations cover current in-house and contract programs under the sponsorship of these three organizations. |
|
| Proceedings of the Annual Mechanics of Composites Review (17th) |
APR 97 |
263 pages |
| Authors:
AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OH NONMETALLIC MATERIALS LAB
|
| This report contains the basic unedited vu-graphs of the presentations at the 'Mechanics' of Composites Review' sponsored jointly by the Non-metallic Materials Division of the Air Force Materials Laboratory, the Structures Division of the Air Force Flight Dynamics Laboratory and the Directorate of Aerospace Sciences of the Air Force Office of Scientific Research. The presentations cover current in-house and contract programs under the sponsorship of these three organizations. |
|
| Spline Variational Theory for Composite Bolted Joints |
JAN 1997 |
29 pages |
| Authors:
E. Iarve; DAYTON UNIV OH RESEARCH INST
|
| Methods for stress redistribution analysis in composite laminates due to matrix cracking were developed. Two approaches were implemented. A conventional mesh overlay method in the crack region to satisfy the crack face boundary conditions and a novel spline basis partitioning method were compared. The conventional approach failed to provide converged stress continuity boundary conditions at the edge of the overlay mesh. The spline basis partitioning method showed accurate stress boundary ... |
|
| Core Programs of High-Performance Composite Materials |
JAN 1997 |
158 pages |
| Authors:
A. Crasto; D. Anderson; R. Esterline; C. Hill; R. Kim; DAYTON UNIV OH RESEARCH INST
|
| Evaluation of composites continued from the previous contract. New modifications, thermo-oxidative stability, and hygrothermal aging of AFR700 composites were studied. E-beam curing of composites was investigated. Bridge rehabilitation using carbon-epoxy composites was demonstrated. Modeling of damage in carbon-carbon fabric-based composites expanded to include 3-D stresses and model composites testing. Double lap-shear adhesives testing successfully compared predicted and actual test damage. Damage around a hole in a composite in tension was ... |
|
| Low-Velocity Impact on Composite Sandwich Plates |
JUL 96 |
361 pages |
| Authors:
Eric J. Herup; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| The objective of the research is to analytically model the response of composite sandwich plates to low velocity impact. A displacement based, plane stress, finite element code is modified for this purpose. Major new algorithms include 5th order Hermitian interpolation, three dimensional equilibrium integration for transverse stress calculations, sandwich core modeling as an elastic plastic foundation, loading by simulated contact with a spherical indentor, adaptive mesh, damage prediction, damage progression ... |
|
| Fracture Resistance of Random Fiber Glass Composites |
FEB 96 |
|
| Authors:
A. C. Garg; C. K. Trotman; COLLEGE OF AERONAUTICS CRANFIELD (UNITED KINGDOM)
|
| The concept of crack growth resistance curve (R-curve) has been applied to random fiber glass composites and analytical relations for R-curve have been obtained. The effect of thickness and the procedure of lamination is studied. It is found that thickness does not affect significantly the fracture characteristics. The analytical relations for R-curve are used to predict the residual strength characteristics and the fracture toughness |
|
| V-LAB: A Virtual Laboratory for Structural Integrity Assessment of Composite Components |
31 JAN 96 |
39 pages |
| Authors:
Eduardo Maos; Timothy R. Wyatt; APPLIED RESEARCH ASSOCIATES INC RALEIGH NC
|
| V-LAB is a Window's-based analysis tool for structural integrity assessment of composite components. The software allows failure investigators to work within 'virtual laboratories' representing different structural levels within a composite component. Data can be exchanged seamlessly between the different labs, allowing results to be easily integrated. A prototype of the V- LAB software system was developed with labs for micromechanics analysis, material definition, and failure analysis of composite laminates and ... |
|
| Simplified Micromechanical Models for Analysis of Interface Debonding in a Fibrous Composite |
DEC 95 |
115 pages |
| Authors:
Jia-Yuarn Guo; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The objective of this study is to develop simplified micromechanical models to analyze the interface debonding between fiber and the matrix materials. Both analytical and simplified finite element models are used to predict the effective transverse elastic modules of fibrous composites with a partial interface crack based on the material properties of their constituents. The simplified finite element model uses springs in the connecting nodes between the fiber and matrix. ... |
|
| Thermal Stresses in End-Heated Layered Media |
DEC 95 |
141 pages |
| Authors:
Jerry R. Couick; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| Thermal stresses in semi-infinite layered beams heated on the end are calculated using an extension to simple bimetallic thermostat theory. Recently, researchers have used the concept of interfacial compliance to determine interlaminar stresses in a simple thermostat of finite length subjected to a uniform temperature increase. In the present work, the thermostat theory is extended to apply to the beams of interest. A closed-form solution to the problem is obtained. ... |
|
| Advanced Polymeric and Metallic Composite Materials for Space and Aerospace Vehicle Structures and Strength Optimization of Composite Structures and their Certification (Les Materiaux Composites Polymeriques et Metalliques Avances pour les Structures des |
DEC 95 |
|
| Authors:
ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRAN CE)
|
| This Lecture Series will present and discuss the scientific problem of advanced polymer and metallic composite materials for aerospace structures, strength optimization of composite structures and their certification. Some challenges of using composite structures, including airframe concept definition are studied. Also fibre orientation optimization principles for composite panels and shells are outlined. Procedures for certification of assemblies made out of composites are dealt with. Certification requirements, including requirements to estimate ... |
|
| Graphite/Epoxy Heat Sink/Mounting for Common Pressure Vessel. |
21 NOV 1995 |
|
| Authors:
Nelson L. Hyman; William R. Braun; James C. Garner; Lawrence R. Larson; Sheleen M. Tuner; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| The graphite-epoxy heat sink and mounting structure is comprised of a mounting structure constructed of a graphite-epoxy material that is mounted around a heat generating pressure vessel located inside a spacecraft. The mounting structure is a graphite-epoxy structure having three segments. The first and third segments are a graphite-epoxy material with a high thermal conductivity but not necessarily capable of withstanding structural stresses. Between these thermal conductive segments is a ... |
|
| Imide/Graphite Composite Degradation Mechanism |
OCT 1995 |
49 pages |
| Authors:
M. Druy; J. Gassner; M. Groleau; R. Kovar; P. Wilson; FOSTER-MILLER INC WALTHAM MA
|
| This report presents the results of the Phase I research undertaken by Foster-Miller, Inc. to establish at the molecular level, the mechanism of degradation of composites employing bismaleimide (BMI) resins when in contact with a corroding metal in an electrolytic saltwater solution. It also discusses Foster-Miller's approach to reducing this degradation by modifying the resin with hydroxyl scavengers. Our results indicated that samples which were modified with hydroxyl scavengers corroded ... |
|
| Bending Deformation Increase of Bending-Extension Coupled Composite Beams Bonded with Actuator(s) |
OCT 1995 |
4 pages |
| Authors:
Po-Yun Tang; NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA
|
| This paper presents the results of three closely related studies on the bending deformation increase of beams made of bending-extension (be) coupled fiber-reinforced composites, such as N-layered regular (equal thickness layers) antisymmetric cross-ply laminates. The load ngs on the beams are either pure bending (without any strain actuation) or strain actuation induced by the actuators (such as lead zirconium titanate P%% drivers) bonded to both or one side of the ... |
|
| Three-Dimensional Effective Property and Strength Prediction of Thick Laminated Composite Media |
OCT 95 |
96 pages |
| Authors:
Travis A. Bogetti; Christopher P. Hoppel; William H. Drysdale; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| An analytical model appropriate for the analysis and design of thick laminated composite media is presented. The model is based on the theoretical work of Chou, Carleone, and Hsu (1972) and predicts the effective three- dimensional thermo-mechanical properties and ultimate strength of thick laminated composite media under applied mechanical and thermal loadings. Various types of lamina constitutive models and lamina failure criteria (including progressive ply failure) have been incorporated in ... |
|
| LAMPAT: A Software Tool for Analyzing and Designing Thick Laminated Composite Structures |
SEP 95 |
64 pages |
| Authors:
Travis A. Bogetti; Christopher P. Hoppel; Bruce P. Burns; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| The U.S. Army Research Laboratory has recently developed an innovative analysis and design software tool for evaluating the mechanical performance of thick section laminated composite material structures. The software tool has been given the name LAMPAT and is intended to be used in conjunction with traditional finite element analysis codes. LAMPAT implements a 'smearing-unsmearing' methodology, an approach that is often employed in the structural analysis of thick multi-ply laminated composite ... |
|
| 3-D Finite Element Method for Micromechanical Analysis in Fibrous Composite Material |
JUN 95 |
59 pages |
| Authors:
Chun-Chun Cheng; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The objective of this thesis was to study whether simplified three dimensional finite element models could be used as a micromechanical model for analysis of stresses at the fiber and matrix level while providing smeared composite properties for the global structural analysis. The mathematical model was programmed using the MATLAB engineering software. For considering interface cracks between the fiber and matrix, springs were modeled in the connecting nodes between the ... |
|
| Analysis of Axial Damping in Segmented Constrained Layer Fibrous Composites |
JUN 95 |
73 pages |
| Authors:
Alan M. Carver; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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| The axial damping in segmented ply specimens is compared with that of continuous ply specimens. Axial damping increases in both designs as the free- edge transverse shear becomes more important. The axial damping of segmented specimens surpasses that of the unsegmented design when small segment aspect ratios are employed. This observed trend corresponds with earlier finite element models but fails to reach magnitudes considered practically important. Theories are presented concerning ... |
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GRAPHITE EPOXY COMPOSITES
