| Comparative Evaluation of Failure Analysis Methods for Composite Laminates |
MAY 96 |
134 pages |
| Authors:
PURDUE UNIV LAFAYETTE IN SCHOOL OF AERONAUTICS AND ASTRONAUTICS
|
 | Over the last three decades, there have been continuous efforts in developing failure criteria for unidirectional fiber composites and their laminates. Currently, there exist a large number of lamina failure criteria and laminate failure analysis methods. In this project, a comprehensive and objective study of lamina and laminate failure criteria was performed. Comparisons among the commonly used failure criteria were made for failure in unidirectional composites under various loading cases. ... |
|
| Wright Laboratory Success Stories. A Review of 1994 |
APR 96 |
163 pages |
| Authors:
WRIGHT LAB WRIGHT-PATTERSON AFB OH
|
| Success stories from 1994/95 that recognize the accomplishments and combined effort of Wright Laboratory scientists and engineers. Stories have been selected from the following categories: TECHNOLOGY TRANSITION -- Technology that has achieved application on a Department of Defense system in development or operation or that has provided 'quick-reaction' response to problems or needs of field organizations; TECHNOLOGY TRANSFER -- Technology that has transferred from the laboratory to the private sector, ... |
|
| PCM Composite Cold Plate |
APR 1996 |
40 pages |
| Authors:
Timothy R. Knowles; ENERGY SCIENCE LABS INC SAN DIEGO CA
|
| This Phase I SBIR project has investigated a lightweight packaging design for phase change materials (PCMs) used in thermal management. To control expansion stress, conventional PCM heat sinks have strong encapsulation that weighs more than the PCM they contain. The objective of this work is to develop PCM heat sinks configured as thin sandwich plates, in which the mass of the encapsulation is a small fraction of the PCM mass. ... |
|
| Constitutive Modeling and Finite Element Analysis of Fatigue - Damage in Metal Matrix Composites |
11 MAR 96 |
160 pages |
| Authors:
George Z. Voyiadjis; Taehyo Park; Ganesh Thiagarajan; LOUISIANA STATE UNIV BATON ROUGE DEPT OF CIVIL ENGINEERING
|
| A micromechanical consistent and systematic theory is developed for the analysis of damage mechanisms in metal matrix composites. A coupled incremental damage and plasticity theory of metal matrix composites is introduced here. This allows damage to be path dependent either on the stress history or the thermodynamic force conjugate to damage. This is achieved through the use of incremental damage tensors. The model involves both overall and local approaches to ... |
|
| On a Pure Finite-Element-Based Methodology for Resin Transfer Mold (RTM) Filling Simulations |
MAR 96 |
44 pages |
| Authors:
R. V. Mohan; N. D. Ngo; K. K. Tamma; K. D. Fickie; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| A pure finite-element-based methodology for resin transfer molding (RTM) process simulations is presented. The formulations are developed starting with the time-dependent mass conservation equation for the resin. Darcy's flow approximations are invoked for the velocity field forming a transient governing equation involving the pressure field and the resin saturation fill factor, which tracks the location of the resin front surface. Finite element approximations are then introduced for both the fill ... |
|
| Synthesis of Net-Shape Ceramic Matrix Composites from Phase Separated Polymeric Precursors |
01 FEB 96 |
|
| Authors:
John S. Haggerty; Dietmar Seyferth; MASSACHUSETTS INST OF TECH CAMBRIDGE
|
 | This program seeks means of fabricating thick cross-section monolithic and composite ceramic components using polymeric ceramic precursors, thereby realizing potential processing and quality advantages. This program's strategy for overcoming longstanding problems is based on developing and maintaining a precisely controlled interconnected pore structure within the reacting part, thus providing a pathway through which gaseous reaction products can escape without damaging the part and into which gaseous reactants can freely penetrate, ... |
|
| 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 ... |
|
| Thermoplastic Ribbon-Ply Bonding Model |
JAN 96 |
61 pages |
| Authors:
Jeffrey A. Hinkley; Joseph M. Marchello; Bernadette C. Messier; NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER
|
| With thermoplastic matrix resins, on-line consolidation of continuous-fiber composite laminates offers the potential of eliminating the post-placement autoclave or oven curing step, thereby simplifying the process and reducing costs. The aim of the present work was to identify key variables in rapid weld-bonding of thermoplastic tow (ribbon) and their relationship to matrix polymer properties and to ribbon microstructure. Theoretical models for viscosity, establishment of ply-ply contact, instantaneous (Velcro) bonding, molecular ... |
|
| Dynamic Deformation of a Ceramic/GRP Composite From KE Impact |
JAN 96 |
55 pages |
| Authors:
E. Strabburger; H. Senf; FRAUNHOFER-GESELLSCHAFT ZUR FOERDERUNG DER ANGEWANDTEN FORSCHUNG E V MUNICH (G ERMANY F R)
|
| Ceramic/GRP (Glass Reinforced Plastic) composite targets were inspected by hemispheric alloy projectiles (L= 55 mm, D = 17 mm, m = 214 g) at velocities of about 1000 m/s. The impact velocities were chosen close to the balisitic limit of this projectile-target combination, which was determined from parametric tests conducted by the U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland, USA. The GRP laminates were S-2 Glass/Polyester fabricated by Simula, ... |
|
| Availability of Aerospace Rayon for SRM Nozzle Insulators |
96 |
|
| Authors:
R. C. Rossi; W. C. Wong; TRW INC SAN BERNARDINO CA
|
| For approximately 30 years, the nozzles of solid rocket motors (SRM) have used an aerospace grade of rayon as a precursor for carbon fabric reinforcement in phenolic composites employed as ablative insulators. Rayon has been the industry mainstay ever since and modern nozzle designs have been dependent upon the properties of carbon, fabric/phenolic, or graphite fabric/ phenolic composites derived from this material. Over the years, the industry has been dependent ... |
|
| Proceedings of the Materials Research Society Symposium on Fracture: Instability Dynamics, Scaling, and Ductile/Brittle Behavior. Volume 409 |
96 |
402 pages |
| Authors:
R. L. Selinger; John J. Mecholsky; Anders E. Carlsson; Edwin R. Fuller Jr; MATERIALS RESEARCH SOCIETY PITTSBURGH PA
|
| This volume contains the papers that were presented at the 1995 MRS Fall Meeting in Symposium Q, entitled 'Fracture: Instability Dynamics, Scaling, and Ductile/Brittle Behavior.' The purpose of the symposium was to bring together the many communities that investigate the fundamentals of fracture, with special sessions on the ductile/brittle transition, fracture at interfaces, fracture in ceramics and composites, dynamic instabilities in crack propagation, and fractals and scaling in fracture. A ... |
|
| Review and Research on Carbon Fiber Reinforced Quartz Used as Thermal Protection Shield |
20 DEC 95 |
29 pages |
| Authors:
Guoting Wu; NATIONAL AIR INTELLIGENCE CENTER WRIGHT-PATTERSON AFB OH
|
| An evaluation was done of the characteristics of fiber reinforced ceramics in radiation thermal protective structures acting as exterior radiation cover plates. Using as a basis typical mechanical environments and thermal environments associated with returnable spacecraft, experimental research was carried out with regard to carbon fiber reinforced quartz-- including such items as small plate reentry thermal simulation tests as well as room temperature vibration, room temperature shock, low temperature vibration, ... |
|
| Method of Making a Lattice Core Sandwich Construction |
12 DEC 1995 |
7 pages |
| Authors:
Hemen Ray; Lee W. Gause; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
|
| A novel form of sandwich construction is disclosed. The lattice core sandwich construction comprises of elongate lattice cells in side-by-side abutment, to present common, lengthwise flat sides that have facesheets co-cured thereto without any secondary bonding. Each lattice cell is formed by wrapping, in alternate patterns, fiber-reinforced, composite bands around commonly-shaped mandrels. Oppositely disposed face sheets are placed against flat sides and the construction co-cured. After co-curing, the mandrels are ... |
|
| Method of Making a Lattice Core Sandwich Construction. |
12 DEC 1995 |
|
| Authors:
Hemen Ray; Lee W. Gause; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A novel form of sandwich construction is disclosed. The lattice core sandwich construction comprises of elongate lattice cells in side-by-side abutment, to present common, lengthwise flat sides that have facesheets co-cured thereto without any secondary bonding. Each lattice cell is formed by wrapping, in alterate patterns, fiber-reinforced, composite bands around commonly-shaped mandrels. Oppositely disposed face sheets are placed against flat sides and the construction co-cured. After co-curing, the mandrels are ... |
|
| 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. ... |
|
| Optimal Solution Selection for Sensitivity-Based Finite Element Model Updating and Structural Damage Detection |
DEC 95 |
215 pages |
| Authors:
Jay A. Renken; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The finite element model has become the standard way in which complex structural systems are modeled, analyzed, and the effects of loading simulated. A new method is developed for comparing the finite element simulation to experimental data, so the model can be validated, which is a critical step before a model can be used to simulate the system. An optimization process for finite element structural dynamic models utilizing sensitivity based ... |
|
| 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 ... |
|
| Design Loads for Fiberglass Bulkhead and Deck Structures |
DEC 95 |
26 pages |
| Authors:
Charles D. Wolverton Jr; COMPUCON GROSSE LLE MI
|
| In order to determine suitable loadings to be applied during fire endurance testing of fiber reinforced plastic (FR P) bulkhead and deck structures, a number of sources were reviewed to determine whether generally- accepted published design load values were available for these structures. Few published listings of design load values were found. It appears that the main reason is widespread reliance on classification society design rules. Also, design loads are ... |
|
| Workstation for Support of Basic Research (HBCU/MI/INFRA PGM) |
30 NOV 95 |
10 pages |
| Authors:
C. R. Truman; Howard L. Schreyer; NEW MEXICO UNIV ALBUQUERQUE DEPT OF MECHANICAL ENGINEERING
|
| The research projects described herein derived computational support from a color graphics workstation provided to the University of New Mexico, Department of Mechanical Engineering, through all equipment grant under the Infrastructure Support Program for Historically Black Colleges and Universities and Minority Institutions (HBCU/MI's). The project topics, faculty investigator and support include: (1) Finite element modeling of suspension flows, Prof Marc Ingber; (2) Finite element simulations of failure mechanisms in quasi-brittle ... |
|
| The Study of Fatigue Behavior for Impacted ARALL Countermeasures |
21 NOV 95 |
11 pages |
| Authors:
Yajun Guo; Yujun Shao; Ruigi Zheng; NATIONAL AIR INTELLIGENCE CENTER WRIGHT-PATTERSON AFB OH
|
| As far as impact damage mechanisms with regard to free ARALL and two types of prestressed ARALL laminates are concerned, surface observations and test measurement analysis without damage were carried out with respect to the propogation of impact damage during fatigue processes. Cumulative fatigue damage models were set up for laminates after impact. Probes were done with regard to the influences of prestressing on fatigue properties after ARALL laminate impact. ... |
|
| Technology for Condensate Return Lines |
NOV 95 |
35 pages |
| Authors:
John Kunsemiller; NAVAL FACILITIES ENGINEERING SERVICE CENTER PORT HUENEME CA
|
| An investigation was conducted by the Naval Facilities Engineering Service Center (NFESC) to determine current and emerging technology for cost- effective, durable materials for condensate return lines associated with district piping systems for central steam distribution on Navy shore facilities. The distributed steam may be used for building heating, cooking, ships supply, and other direct-use processes. This investigation sought to identify materials and specific technology to improve the reliability and ... |
|
| Carbon Fiber Reinforced Glass Matrix Composites for Satellite Applications |
31 OCT 95 |
143 pages |
| Authors:
William K. Tredway; UNITED TECHNOLOGIES RESEARCH CENTER EAST HARTFORD CT
|
| The development of carbon fiber reinforced glass and glass-ceramic matrix composites for satellite applications is described. A variety of carbon fibers (HMU, P-i 00, FT7OO, K ii OOX) have been used to reinforce borosilicate glass and BMAS glass-ceramics to create high performance composite materials useful for structural applications in space. Fundamental material properties that are described in this report include tensile and compressive stress-strain behavior, tensile and compressive fatigue behavior, ... |
|
| An Experimental Investigation of Nonlinear Behaviour of Beams and Plates Excited to High Levels of Dynamic Response |
31 OCT 95 |
470 pages |
| Authors:
Howard F. Wolfe; Cynthia A. Shroyer; Dansen L. Brown; Larry W. Simmons; WRIGHT LAB WRIGHT-PATTERSON AFB OH
|
| Dynamic tests were conducted utilizing clamped aluminium and composite beams and plates excited by shakers and acoustic progressive wave tubes. The total strains and the components, bending and axial and the displacements were measured with increasing levels of excitation. Bistable behaviour is observed with sinusoidal excitation for both the beams and plates. The beams randomly excited exhibit a slight frequency shift and peak broadening, which can be attributed to an ... |
|
| 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 ... |
|
| Advanced Polymer Components. Volume 2 |
OCT 95 |
201 pages |
| Authors:
John Rusek; PHILLIPS LAB EDWARDS AFB CA
|
| The Advanced Polymer Components Initiative began in December l989. The initial purpose of the program was to explore advanced engineering polymers for use as rocket propulsion components. As research progressed it became apparent that advanced thermoplastics in general were highly dependent on processing and post-processing as well as on chemical composition and morphology. This realization led to a branching of the original objective into an applications research goal and a ... |
|
| Investigation of Microstructural Brazing of Al/C Fiber Composites |
27 SEP 95 |
19 pages |
| Authors:
Yi Guo; Peng Lin; Zhijing He; NATIONAL AIR INTELLIGENCE CENTER WRIGHT-PATTERSON AFB OH
|
| The metal materials (Mg, Al, Ti and alloys) and the reinforcing components (Carbon fiber, SiC whiskers, particles, etc.) used in forming metal matrix composites have great mismatch between their physical, chemical and mechanical properties. The study of fabricating Al/C fiber composites and using them as structural materials is becoming an important new field in material science. An investigation on the microstructure bonding technology is not only of great significance for ... |
|
| The Reliability of Laser Reflowed Sn-Ag Solder Joints |
19 SEP 95 |
28 pages |
| Authors:
C. H. Raeder; D. L. Millard; R. W. Messler; RENSSELAER POLYTECHNIC INST TROY NY
|
| Measurement of thermal cycling stress-strain hysteresis for soldered joints is described by several authors. In the first study to report experimentally measured thermomechanical (T-M) stress-strain hysteresis, only a single ceramic leadless chip carrier soldered to a fiberglass reinforced polymer (FR4) printed wiring board and a single thermal cycle was used throughout the study. These conditions prescribe one value of k' and one value of gamma sub fc. Only stable loop ... |
|
| Static and Fatigue Damage in High Temperature Composites |
14 SEP 95 |
95 pages |
| Authors:
G. J. Dvorak; Y. A. Bahei-el-Din; RENSSELAER POLYTECHNIC INST TROY NY
|
| This final report presents the experimental and theoretical work performed in our research program on static and fatigue damage in high temperature composites. The theoretical part focused on development and implementation of a new Transformation Field Analysis (TFA) for inelastic laminates, which employs unit-call, periodic array models, as well as averaging micromechanical models together with any constitutive law for thermo- viscoplastic and other inelastic deformation. Moreover, we have initiated modeling ... |
|
| Research Proposal Quarterly Status Report, July-September 1995 |
SEP 95 |
52 pages |
| Authors:
AIR FORCE OFFICE OF SCIENTIFIC RESEARCH BOLLING AFB DC
|
| THIS RESEARCH PROPOSAL STATUS REPORT IS PUBLISHED QUARTERLY AS OF MARCH, JUNE, SEPTEMBER AND DECEMBER OF EACH YEAR. |
|
| 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 ... |
|
| Titanium Matrix Composite Processing. Tapecast Preforms |
31 AUG 95 |
11 pages |
| Authors:
John V. Busch; IBIS ASSOCIATES INC WELLESLEY MA
|
| Titanium matrix composites (TMC's) would enable significant advances in commercial and military aviation product design, yet at the present there has been little implementation into promising engine applications. In general, economical processing technologies and reinforcing fibers are not yet available. This report focuses on evaluating the economic potential of one promising technology to produce TMC preforms. This process, known as tapecasting, has been developed at Textron Specially ... |
|
| Dynamics of Cracked Composite Material Structures. |
15 AUG 1995 |
44 pages |
| Authors:
W. M. Ostachowicz; M. Krawczuk; A. Zak; POLISH ACADEMY OF SCIENCES GDANSK INST OF FLUID FLOW MACHINERY
|
| As a result of this work models of the finite beam and plate elements have been elaborated, to enable the analysis of the influence of the fatigue cracks and delaminations on the dynamic characteristics of the constructions made of unidirectional composite materials. The method of modelling the crack or delamination presented in the report enables an easy modification of the elaborated elements according to its specific damage (oblique crack, two-side ... |
|
| Controlled Dispersion of the Extensional Wave in Composite Isotropic and Transversely Isotropic Rods |
14 AUG 95 |
52 pages |
| Authors:
Marilyn J. Berliner; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
|
| The dispersion of extensional waves in composite isotropic and transversely isotropic rods is investigated. The equations of motion of an infinitely long, layered rod with a transversely isotropic core and transversely isotropic casing are developed using the three-dimensional equations of elasticity. Simplifications to the equations of motion for axisymmetric modes of wave propagation and for material isotropy are presented. Methodologies for controlling the range of dispersion or the maximum phase ... |
|
| Passive Vibration Damping Materials: Piezoelectric Ceramic Composites for Vibration Damping Applications |
AUG 95 |
81 pages |
| Authors:
Shoko Yoshikawa; R. Meyer; J. Witham; S. Y. Agadda; G. Lesieutre; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| The use of passive piezoelectric damping using PZT ceramics has been demonstrated in theory and the number of experiments. The effort was multifaceted. For application of the shunted passive piezoelectric damping of structural composites, piezoelectric ceramic fibers (PZT family) of several tens of micron diameter were produced using sol gel spinning process. Since these fibers were not strong enough to withstand handling for continuous poling process, slurry extruded PZT MicroRods,(12O ... |
|
| Philosophical Transactions: Physical Science and Engineering; High- Temperature Structural Materials. Volume 351, Number 1697 |
15 JUN 95 |
216 pages |
| Authors:
R. W. Cahn; A. G. Evans; M. McLean; IMPERIAL COLL OF SCIENCE TECHNOLOGY ANDMEDICINE LONDON (UNITED KINGDOM)
|
| The Final Proceedings for High Temperature Structural Materials was held from 2 November 1994 to 3 November 1994. |
|
| High-Energy-Absorbing Enclosure for Internal Explosion Containment. |
15 JUN 1995 |
36 pages |
| Authors:
Roger M. Crane; Paul A. Coffin; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A structural enclosure, box-like for many embodiments, which effectively contains an explosion, thereupon remaining virtually intact and minimizing fragmentation. The Structural wall has a Sandwich-like arrangement of two fiber-reinforced matrix material skins and a foam core situated between the two skins, at least one skin having fiber-reinforced high strain-to-failure viscoelastic matrix material. The core foam material selectively varies in density so as to provide appropriate rigidity or flexibility at different ... |
|
| Experimental Estimation of Process Parameters in Resin Transfer Molding |
14 JUN 95 |
14 pages |
| Authors:
Robert J. Duh; Robert S. Maier; Jeffrey H. Vogel; MINNESOTA UNIV MINNEAPOLIS DEPT OF MECHANICAL ENGINEERING
|
| A numerical method is presented for the estimation of experimental resin transfer molding (RTM) process parameters from in-mold temperature data. The approach is built around the simulation of either radial or axial flow of reactive resins through a fiber preform inside a mold cavity. The simulation considers a non-isothermal environment, with one-dimensional flow and one- dimensional heat transfer, and allows for either pressure or flow rate controlled inlet conditions. Based ... |
|
| Lattice Core Sandwich Construction |
13 JUN 1995 |
7 pages |
| Authors:
Hemen Ray; Lee W. Gause; NAVAL AIR WARFARE CENTER AIRCRAFT DIV PATUXENT RIVER MD
|
| A novel form of sandwich construction is disclosed. The lattice core sandwich construction comprises of elongate lattice cells in side-by-side abutment, to present common, lengthwise flat sides that have facesheets co-cured thereto without any secondary bonding. Each lattice cell is formed by wrapping, in alternate patterns, fiber-reinforced, composite bands around commonly-shaped mandrels. Oppositely disposed face sheets are placed against flat sides and the construction co-cured. After co-curing, the mandrels are ... |
|
| The Cyclic Fatigue Behaviour of Adhesive Joints |
12 JUN 95 |
7 pages |
| Authors:
A. J. Kinloch; T. Toh; IMPERIAL COLL OF SCIENCE AND TECHNOLOGY LONDON (UNITED KINGDOM) DEPT OF MECHA NICAL ENGINEERING
|
| In the last six months we have: (a) Concentrated our efforts on the fatigue failure of carbon-fibre PEEK/AFl63 lap joints, and in particular we have started to predict the life time of single-lap joints under cyclic fatigue loading. The analysis is based on data obtained from double cantilever beam (DCB) fracture mechanics tests. (b) Further, we have been successful in measuring the rate of crack growth in lap joints during ... |
|
| 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 ... |
|
| Design and Analysis of Composite Wraps for Concrete Columns |
JUN 95 |
35 pages |
| Authors:
Christopher P. Hoppwl; Travis A. Bogetti; John W. Gillespie Jr; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Composite jackets for concrete columns can potentially renew deteriorated structures and improve seismic resistance. Several experimental investigations have demonstrated that composite wraps increase load carrying capacity and ductility of concrete columns subjected to axial compression. This paper describes a theoretical model to predict the nonlinear stress-strain response of the wrapped columns as a function of geometry and the constitutive behavior of the concrete and column wrap. Model predictions are compared ... |
|
| 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
|
| 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 ... |
|
| Naval Undersea Warfare Center Division Newport Technical Digest. Structural Acoustics |
JUN 95 |
115 pages |
| Authors:
Richard H. Nadolink; Ding Lee; James C. Meng; Albert H. Nuttall; Norman L. Owsley; NAVAL UNDERSEA WARFARE CENTER NEWPORT DIV RI
|
| The theme of this issue of the Naval Undersea Warfare Center Division Newport's Technical Digest is structural acoustics and composite structures. Structural acoustics is that field of physics dealing with the propagation of time-wise varying motion in solid bodies and their interaction with acoustic media. The practical application of structural acoustics is in noise control. The problems in this area of engineering science are complex because, unlike acoustic fluids, there ... |
|
| Handbook on Continuous Fiber-Reinforced Ceramic Matrix Composites |
JUN 95 |
|
| Authors:
Richard L. Lehman; Said K. El-Rahaiby; John B. Wachtman Jr; CERAMICS INFORMATION ANALYSIS CENTER WEST LAFAYETTE IN
|
| This handbook is organized into fifteen chapters which comprehensively cover the topic of continuous fiber ceramic composites (CFCCs) from theoretical considerations through raw materials and processing to design, applications, and property topics. Perhaps processing science and technology appropriately receive the most emphasis in this handbook since the development of processing technologies has most significantly advanced CFCC material properties and applications. Topics such as chemical vapor infiltration, fiber/ matrix interfaces, polymer ... |
|
| Micromechanics Modeling and Analysis of Haversian Compact Bone Tissue as a Fiber Reinforced Composite Material |
MAY 95 |
38 pages |
| Authors:
Harry A. Hogan; TEXAS A AND M UNIV COLLEGE STATION DEPT OF MECHANICAL ENGINEERING
|
| Haversian compact bone tissue is being studied theoretically and experimentally to characterize its behavior as a fiber reinforced composite material with the aim of biomimicking its salient features. Analytical and finite element based composite micromechanics techniques have been developed and evaluated for theoretical modeling of structure/property relationships. two- dimensional finite element models of material representative volume elements have been used to predict variations ... |
|
| Feasibility of an Electromagnetic Diaphragm Compressor for Cryocoolers |
MAY 1995 |
62 pages |
| Authors:
Dantam K. Rao; PRECISION MAGNETIC BEARING SYSTEMS COHOES NY
|
| This Phase I SBIR report documents the establishment of feasibility of a electromagnetic diaphragm compressor which is designed to drive cryocoolers. Two prototype compressors were built and tested as part of this feasibility establishment program. The first prototype used permanent magnet bias while the second prototype used electromagnet bias. Testing the first prototype indicated that the diaphragm used in it is too stiff for satisfactory operation. As a result, electromagnet ... |
|
| Composite Failure Analysis Handbook Update Number 1 |
APR 95 |
266 pages |
| Authors:
Greg Walker; BOEING DEFENSE AND SPACE GROUP SEATTLE WA
|
| This report supplements the data and analyses provided in the previously released 'Composite Failure Analysis Handbook,' WL-TR-91-4032. It contains fractographic data from failed composite test specimens as well as case 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 ... |
|
| Effects of Hydrostatic Pressure on the Mechanical Behavior of Composite Materials |
APR 95 |
64 pages |
| Authors:
Christopher P. Hoppel; Travis A. Bogetti; John W. Gillespie Jr; ARMY RESEARCH LAB ABERDEEN PROVING GROUND MD
|
| Hydrostatic pressure can cause significant changes in the mechanical properties of composite materials. A thorough understanding of these effects is essential for the effective design of composite structures for high-pressure applications. In this report, the literature on the effects of hydrostatic pressure on the mechanical behavior of composite materials is reviewed. This includes a general description of the effects of hydrostatic pressure on unreinforced polymers and a detailed critique of ... |
|
| Development of a Variable Frequency Microwave Processing System for Post-Curing of Thermoset Polymer Matrix Composite Materials |
28 FEB 95 |
14 pages |
| Authors:
Arvid Johnson; LAMBDA TECHNOLOGIES ACQUISITION CORP RALEIGH NC
|
| Using a Variable frequency Microwave Furnace (VFMF) technology, Lambda Technologies has demonstrated the ability to tune to the optimum incident frequency for best coupling into a given material structure (e.g., polymer matrix composite, PMC), and then by sweeping around that incident center frequency, producing uniform energy distribution throughout the cavity and sample volume. Hence, the advantages of microwave energy---enhanced reaction rates, reduced process time, and heat generation at the molecular ... |
|
| Proceedings of the Annual Meeting (18th) of the Adhesion Society Held at Hilton Head, South Carolina on 19-22 February 1995 |
22 FEB 95 |
398 pages |
| Authors:
ADHESION SOCIETY INC BLACKSBURG VA
|
| This document is a collection of abstracts of papers presented at the 18th Annual Adhesion Society Meeting held at Hilton Head, SC on February 19-22, 1995. The program was chaired by Joseph W. Holubka. Three areas of adhesion science will be emphasized in this years meeting. These areas include: New Materials for Adhesives and Coatings; Small Particle Adhesion; and Chemical/ Physical Characterization of Adhesive Interactions. Two sessions will be assigned ... |
|
Reports by Keyword(s)
FIBER REINFORCED COMPOSITES
