Sample records for advanced composite structures

  1. On the Mechanical Behavior of Advanced Composite Material Structures (United States)

    Vinson, Jack

    During the period between 1993 and 2004, the author, as well as some colleagues and graduate students, had the honor to be supported by the Office of Naval Research to conduct research in several aspects of the behavior of structures composed of composite materials. The topics involved in this research program were numerous, but all contributed to increasing the understanding of how various structures that are useful for marine applications behaved. More specifically, the research topics focused on the reaction of structures that were made of fiber reinforced polymer matrix composites when subjected to various loads and environmental conditions. This included the behavior of beam, plate/panel and shell structures. It involved studies that are applicable to fiberglass, graphite/carbon and Kevlar fibers imbedded in epoxy, polyester and other polymeric matrices. Unidirectional, cross-ply, angle ply, and woven composites were involved, both in laminated, monocoque as well as in sandwich constructions. Mid-plane symmetric as well as asymmetric laminates were studied, the latter involving bending-stretching coupling and other couplings that only can be achieved with advanced composite materials. The composite structures studied involved static loads, dynamic loading, shock loading as well as thermal and hygrothermal environments. One major consideration was determining the mechanical properties of composite materials subjected to high strain rates because the mechanical properties vary so significantly as the strain rate increases. A considerable number of references are cited for further reading and study for those interested.

  2. Applications for thermal NDT on advanced composites in aerospace structures (United States)

    Baughman, Steve R.


    Following several years of investigating active thermal imaging techniques, Lockheed Martin Aeronautical Systems Company (LMASC) has introduced a portable, time-dependent thermography (TDT) system into the production inspection environment. Originally pursued as a rapid, non-contacting, nondestructive evaluation (NDE) tool for inspecting large surface areas, the TDT system has proven most useful as a rapid verification tool on advanced composite assemblies. TDT is a relatively new NDE methodology as compared to conventional ultrasonic and radiography testing. SEveral technical issues are being addressed as confidence in the system's capabilities increase. These include inspector training and certification, system sensitivity assessments, and test results interpretation. Starting in 1991, LMASC began a beta-site evaluation of a prototype TDT system developed by the Institute of Manufacturing Research at Wayne State University. This prototype was the forerunner of the current production system, which is offered commercially as a fully integrated thermal NDE system. Applications investigated to data include quality assurance of advanced aerospace composite structures/assemblies for disbonds/voids between skin and core. TDT has a number of advantages over traditional NDT methods. The process of acquiring thermal images is fast, and can decrease inspection time required to locate suspect areas. The system also holds promise for depot level inspections due to its portability. This paper describes a systematic approach to implementing TDT into the production inspection arena.

  3. Advanced fiber-composite hybrids--A new structural material (United States)

    Chamis, C. C.; Lark, R. F.; Sullivan, T. L.


    Introduction of metal foil as part of matrix and fiber composite, or ""sandwich'', improves strength and stiffness for multidirectional loading, improves resistance to cyclic loading, and improves impact and erosion resistance of resultant fiber-composite hybrid structure.

  4. In-Situ Investigation of Advanced Structural Coatings and Composites (United States)

    Ustundag, Ersan


    The premise of this project is a comprehensive study that involves the in-situ characterization of advanced coatings and composites by employing both neutron and x-ray diffraction techniques in a complementary manner. The diffraction data would then be interpreted and used in developing or validating advanced micromechanics models with life prediction capability. In the period covered by this report, basic work was conducted to establish the experimental conditions for various specimens and techniques. In addition, equipment was developed that will allow the in-situ studies under a range of conditions (stress, temperature, atmosphere, etc.).

  5. Advanced Ceramic Matrix Composites with Multifunctional and Hybrid Structures (United States)

    Singh, Mrityunjay; Morscher, Gregory N.


    Ceramic matrix composites are leading candidate materials for a number of applications in aeronautics, space, energy, and nuclear industries. Potential composite applications differ in their requirements for thickness. For example, many space applications such as "nozzle ramps" or "heat exchangers" require very thin (structures whereas turbine blades would require very thick parts (> or = 1 cm). Little is known about the effect of thickness on stress-strain behavior or the elevated temperature tensile properties controlled by oxidation diffusion. In this study, composites consisting of woven Hi-Nicalon (trademark) fibers a carbon interphase and CVI SiC matrix were fabricated with different numbers of plies and thicknesses. The effect of thickness on matrix crack formation, matrix crack growth and diffusion kinetics will be discussed. In another approach, hybrid fiber-lay up concepts have been utilized to "alloy" desirable properties of different fiber types for mechanical properties, thermal stress management, and oxidation resistance. Such an approach has potential for the C(sub I)-SiC and SiC(sub f)-SiC composite systems. CVI SiC matrix composites with different stacking sequences of woven C fiber (T300) layers and woven SiC fiber (Hi-Nicalon (trademark)) layers were fabricated. The results will be compared to standard C fiber reinforced CVI SiC matrix and Hi-Nicalon reinforced CVI SiC matrix composites. In addition, shear properties of these composites at different temperatures will also be presented. Other design and implementation issues will be discussed along with advantages and benefits of using these materials for various components in high temperature applications.

  6. Advanced Design of Composite Steel-Concrete Structural element

    Directory of Open Access Journals (Sweden)

    Dr. D. R. Panchal


    Full Text Available Composite framing system consisting of steel beams acting interactively with metal deck-concrete slab and concrete encased composite columns, has been as a viable alternative to the conventional steel or reinforced concrete system in the high-rise construction. However, in Indian context, it is comparatively new and no appropriate design codes are available for the same. Complications in the analysis and design of composite structures have led numerous researchers to develop simplified methods so as to eliminate a number of large scale tests needed for the design. In the present work, a simplified method of composite slabs, beams and columns design is used and software is developed with pre- and post- processing facilities in VB.NET. All principal design checks are incorporated in the software. The full and partial shear connection and the requirement for transverse reinforcement are also considered. To facilitate direct selection of steel section, a database is prepared and is available at the back end with the properties of all standard steel sections. Screen shots are included in the paper to illustrate the method employed for selecting the appropriate section and shear connectors and thus to verify the design adequacy.

  7. Advanced ultrasonic testing of complex shaped composite structures (United States)

    Dolmatov, D.; Zhvyrblya, V.; Filippov, G.; Salchak, Y.; Sedanova, E.


    Due to the wide application of composite materials it is necessary to develop unconventional quality control techniques. One of the methods that can be used for this purpose is ultrasonic tomography. In this article an application of a robotic ultrasonic system is considered. Precise positioning of the robotic scanner and path generating are defined as ones of the most important aspects. This study proposes a non-contact calibration method of a robotic ultrasonic system. Path of the scanner requires a 3D model of controlled objects which are created in accordance with the proposed algorithm. The suggested techniques are based on implementation of structured light method.

  8. Project on strengthening of structures using advanced composites

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    Recuero, A.


    Full Text Available Restoration, strengthening and rehabilitation of buildings becomes one of the more interesting aspects of the use of composites. Construction industry has not yet accepted the wide structural use of these new materials because it does not know the advantages of composites in comparison with traditional materials, such as concrete or steel. Engineers involved in design and construction are conservative and resist to changes. They require codes and specifications, what makes that an entity should lead the use of the new material or technology. At present, the experience needed to prepare those codes does not exist. Experimental tests and successful cases are necessary for the acceptance of these materials in construction. A project is presented, with the aim to provide the experimental basis, needed to update design codes and standards, and the technology for the use of these new composites in building and civil structures strengthening, taking actual pathology, quality and durability into account, as well as urban aesthetics. Research specialists in composites, structural analysis and testing, and in structural pathology, as well as composites and adhesives manufacturers and users, designers and final users will co-work in this project. This will allow that all relevant aspects of the problem be considered.

    La restauración, refuerzo o rehabilitación de estructuras resulta ser uno de los campos de aplicación de mayor interés y más directamente relacionado con los nuevos materiales compuestos. La Industria de la Construcción no ha aceptado aún el uso estructural extenso de los nuevos materiales compuestos porque todavía no conoce bien sus ventajas respecto a los materiales tradicionales, tales como el hormigón o el acero. Los profesionales implicados en el proyecto y en la ejecución de obras suelen ser conservadores y resistirse a los cambios. Para aceptar un nuevo material requieren disponer de normativa relativa a la nueva

  9. Advanced composite structural concepts and materials technologies for primary aircraft structures: Advanced material concepts (United States)

    Lau, Kreisler S. Y.; Landis, Abraham L.; Chow, Andrea W.; Hamlin, Richard D.


    To achieve acceptable performance and long-term durability at elevated temperatures (350 to 600 F) for high-speed transport systems, further improvements of the high-performance matrix materials will be necessary to achieve very long-term (60,000-120,000 service hours) retention of mechanical properties and damage tolerance. This report emphasizes isoimide modification as a complementary technique to semi-interpenetrating polymer networks (SIPN's) to achieve greater processibility, better curing dynamics, and possibly enhanced thermo-mechanical properties in composites. A key result is the demonstration of enhanced processibility of isoimide-modified linear and thermo-setting polyimide systems.

  10. Composite Structures Manufacturing Facility (United States)

    Federal Laboratory Consortium — The Composite Structures Manufacturing Facility specializes in the design, analysis, fabrication and testing of advanced composite structures and materials for both...

  11. Evaluation of Advanced Composite Structures Technologies for Application to NASA's Vision for Space Exploration (United States)

    Tenney, Darrel R.


    AS&M performed a broad assessment survey and study to establish the potential composite materials and structures applications and benefits to the Constellation Program Elements. Trade studies were performed on selected elements to determine the potential weight or performance payoff from use of composites. Weight predictions were made for liquid hydrogen and oxygen tanks, interstage cylindrical shell, lunar surface access module, ascent module liquid methane tank, and lunar surface manipulator. A key part of this study was the evaluation of 88 different composite technologies to establish their criticality to applications for the Constellation Program. The overall outcome of this study shows that composites are viable structural materials which offer from 20% to 40% weight savings for many of the structural components that make up the Major Elements of the Constellation Program. NASA investment in advancing composite technologies for space structural applications is an investment in America's Space Exploration Program.

  12. A study on the utilization of advanced composites in commercial aircraft wing structure: Executive summary (United States)

    Watts, D. J.


    The overall wing study objectives are to study and plan the effort by commercial transport aircraft manufacturers to accomplish the transition from current conventional materials and practices to extensive use of advanced composites in wings of aircraft that will enter service in the 1985-1990 time period. Specific wing study objectives are to define the technology and data needed to support an aircraft manufacturer's commitment to utilize composites primary wing structure in future production aircraft and to develop plans for a composite wing technology program which will provide the needed technology and data.

  13. Structural Framework for Flight: NASA's Role in Development of Advanced Composite Materials for Aircraft and Space Structures (United States)

    Tenney, Darrel R.; Davis, John G., Jr.; Johnston, Norman J.; Pipes, R. Byron; McGuire, Jack F.


    This serves as a source of collated information on Composite Research over the past four decades at NASA Langley Research Center, and is a key reference for readers wishing to grasp the underlying principles and challenges associated with developing and applying advanced composite materials to new aerospace vehicle concepts. Second, it identifies the major obstacles encountered in developing and applying composites on advanced flight vehicles, as well as lessons learned in overcoming these obstacles. Third, it points out current barriers and challenges to further application of composites on future vehicles. This is extremely valuable for steering research in the future, when new breakthroughs in materials or processing science may eliminate/minimize some of the barriers that have traditionally blocked the expanded application of composite to new structural or revolutionary vehicle concepts. Finally, a review of past work and identification of future challenges will hopefully inspire new research opportunities and development of revolutionary materials and structural concepts to revolutionize future flight vehicles.

  14. A Study of the Utilization of Advanced Composites in Fuselage Structures of Commercial Aircraft (United States)

    Watts, D. J.; Sumida, P. T.; Bunin, B. L.; Janicki, G. S.; Walker, J. V.; Fox, B. R.


    A study was conducted to define the technology and data needed to support the introduction of advanced composites in the future production of fuselage structure in large transport aircraft. Fuselage structures of six candidate airplanes were evaluated for the baseline component. The MD-100 was selected on the basis of its representation of 1990s fuselage structure, an available data base, its impact on the schedule and cost of the development program, and its availability and suitability for flight service evaluation. Acceptance criteria were defined, technology issues were identified, and a composite fuselage technology development plan, including full-scale tests, was identified. The plan was based on composite materials to be available in the mid to late 1980s. Program resources required to develop composite fuselage technology are estimated at a rough order of magnitude to be 877 man-years exclusive of the bird strike and impact dynamic test components. A conceptual composite fuselage was designed, retaining the basic MD-100 structural arrangement for doors, windows, wing, wheel wells, cockpit enclosure, major bulkheads, etc., resulting in a 32 percent weight savings.

  15. Advanced composite materials and processes (United States)

    Baucom, Robert M.


    Composites are generally defined as two or more individual materials, which, when combined into a single material system, results in improved physical and/or mechanical properties. The freedom of choice of the starting components for composites allows the generation of materials that can be specifically tailored to meet a variety of applications. Advanced composites are described as a combination of high strength fibers and high performance polymer matrix materials. These advanced materials are required to permit future aircraft and spacecraft to perform in extended environments. Advanced composite precursor materials, processes for conversion of these materials to structures, and selected applications for composites are reviewed.

  16. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications. (United States)

    Di Sante, Raffaella


    In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.

  17. Fibre Optic Sensors for Structural Health Monitoring of Aircraft Composite Structures: Recent Advances and Applications

    Directory of Open Access Journals (Sweden)

    Raffaella Di Sante


    Full Text Available In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.

  18. Study of advanced composite structural design concepts for an arrow wing supersonic cruise configuration, task 3 (United States)


    A structural design study was conducted to assess the relative merits of structural concepts using advanced composite materials for an advanced supersonic aircraft cruising at Mach 2.7. The configuration and structural arrangement developed during Task I and II of the study, was used as the baseline configuration. Allowable stresses and strains were established for boron and advanced graphite fibers based on projected fiber properties available in the next decade. Structural concepts were designed and analyzed using graphite polyimide and boron polyimide, applied to stiffened panels and conventional sandwich panels. The conventional sandwich panels were selected as the structural concept to be used on the wing structure. The upper and lower surface panels of the Task I arrow wing were redesigned using high-strength graphite polyimide sandwich panels over the titanium spars and ribs. The ATLAS computer system was used as the basis for stress analysis and resizing the surface panels using the loads from the Task II study, without adjustment for change in aeroelastic deformation. The flutter analysis indicated a decrease in the flutter speed compared to the baseline titanium wing design. The flutter analysis indicated a decrease in the flutter speed compared to the baseline titanium wing design. The flutter speed was increased to that of the titanium wing, with a weight penalty less than that of the metallic airplane.

  19. A hybrid method for damage detection and quantification in advanced X-COR composite structures (United States)

    Neerukatti, Rajesh Kumar; Rajadas, Abhishek; Borkowski, Luke; Chattopadhyay, Aditi; Huff, Daniel W.


    Advanced composite structures, such as foam core carbon fiber reinforced polymer composites, are increasingly being used in applications which require high strength, high in-plane and flexural stiffness, and low weight. However, the presence of in situ damage due to manufacturing defects and/or service conditions can complicate the failure mechanisms and compromise their strength and reliability. In this paper, the capability of detecting damages such as delaminations and foam-core separations in X-COR composite structures using non-destructive evaluation (NDE) and structural health monitoring (SHM) techniques is investigated. Two NDE techniques, flash thermography and low frequency ultrasonics, were used to detect and quantify the damage size and locations. Macro fiber composites (MFCs) were used as actuators and sensors to study the interaction of Lamb waves with delaminations and foam-core separations. The results indicate that both flash thermography and low frequency ultrasonics were capable of detecting damage in X-COR sandwich structures, although low frequency ultrasonic methods were capable of detecting through thickness damages more accurately than flash thermography. It was also observed that the presence of foam-core separations significantly changes the wave behavior when compared to delamination, which complicates the use of wave based SHM techniques. Further, a wave propagation model was developed to model the wave interaction with damages at different locations on the X-COR sandwich plate.

  20. Study of advanced composite structural design concepts for an arrow wing supersonic cruise configuration (United States)

    Turner, M. J.; Grande, D. L.


    Based on estimated graphite and boron fiber properties, allowable stresses and strains were established for advanced composite materials. Stiffened panel and conventional sandwich panel concepts were designed and analyzed, using graphite/polyimide and boron/polyimide materials. The conventional sandwich panel was elected as the structural concept for the modified wing structure. Upper and lower surface panels of the arrow wing structure were then redesigned, using high strength graphite/polyimide sandwich panels, retaining the titanium spars and ribs from the prior study. The ATLAS integrated analysis and design system was used for stress analysis and automated resizing of surface panels. Flutter analysis of the hybrid structure showed a significant decrease in flutter speed relative to the titanium wing design. The flutter speed was increased to that of the titanium design by selective increase in laminate thickness and by using graphite fibers with properties intermediate between high strength and high modulus values.

  1. Development of damped metal-matrix composites for advanced structural applications. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    Updike, C.A.; Bhagat, R.B.


    The development of damped metal matrix composite structures for advanced applications has been investigated by the use of two different approaches: (1) the development of metal matrix composites with high intrinsic damping compared to that of the matrix material, and (2) the development of coated metal matrix composites with high structural damping compared to that of the composite substrates. The two different approaches are analyzed in terms of their potential for improved damping and feasibility for structural applications. Damping was measured by the transverse vibration of free-free beams using the bandwidth technique by a laser vibrometer under ambient conditions. The damping measurements were made over a wide range of frequencies (.7 kHz to 25.6 kHz) at low strain amplitudes (10 to the -10 power to 10 to the -7 power). Materials investigated for their tensile stiffness, strength, and damping performance include mechanically alloyed (MA) Aluminum-Magnesium, SiC(p)/Aluminum-Copper (MA), SiC(p)/AL, AL2O3(p)/AL, SiC(W)/AL, planar random Gr/AL, unidirectional Gr/AL and unidirectional SiC(Nicalon)/AL composites. The effects of coatings of high damping metals (nitinol and incramute) on 6061-T6 AL and AL2O3(p)/AL substrates have also been studied. The AL-Mg (MA), SiC(p)/AL (MA), SiC(W)/AL and th AL2O3(p)/AL composites show no significant improvement in damping compared with that of the 6061-T6 AL.

  2. Study on utilization of advanced composites in commercial aircraft wing structures. Volume 1: Executive summary (United States)

    Sakata, I. F.; Ostrom, R. B.; Cardinale, S. V.


    The effort required by commercial transport manufacturers to accomplish the transition from current construction materials and practices to extensive use of composites in aircraft wings was investigated. The engineering and manufacturing disciplines which normally participate in the design, development, and production of an aircraft were employed to ensure that all of the factors that would enter a decision to commit to production of a composite wing structure were addressed. A conceptual design of an advanced technology reduced energy aircraft provided the framework for identifying and investigating unique design aspects. A plan development effort defined the essential technology needs and formulated approaches for effecting the required wing development. The wing development program plans, resource needs, and recommendations are summarized.

  3. High Temperature Advanced Structural Composites. Volume 2. Ceramic Matrix Composites, Fiber Processing and Properties, and Interfaces (United States)


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  4. Advanced Deployable Shell-Based Composite Booms for Small Satellite Structural Applications Including Solar Sails (United States)

    Fernandez, Juan M.


    State of the art deployable structures are mainly being designed for medium to large size satellites. The lack of reliable deployable structural systems for low cost, small volume, rideshare-class spacecraft severely constrains the potential for using small satellite platforms for affordable deep space science and exploration precursor missions that could be realized with solar sails. There is thus a need for reliable, lightweight, high packaging efficiency deployable booms that can serve as the supporting structure for a wide range of small satellite systems including solar sails for propulsion. The National Air and Space Administration (NASA) is currently investing in the development of a new class of advanced deployable shell-based composite booms to support future deep space small satellite missions using solar sails. The concepts are being designed to: meet the unique requirements of small satellites, maximize ground testability, permit the use of low-cost manufacturing processes that will benefit scalability, be scalable for use as elements of hierarchical structures (e.g. trusses), allow long duration storage, have high deployment reliability, and have controlled deployment behavior and predictable deployed dynamics. This paper will present the various rollable boom concepts that are being developed for 5-20 m class size deployable structures that include solar sails with the so-called High Strain Composites (HSC) materials. The deployable composite booms to be presented are being developed to expand the portfolio of available rollable booms for small satellites and maximize their length for a given packaged volume. Given that solar sails are a great example of volume and mass optimization, the booms were designed to comply with nominal solar sail system requirements for 6U CubeSats, which are a good compromise between those of smaller form factors (1U, 2U and 3U CubeSats) and larger ones (12 U and 27 U future CubeSats, and ESPA-class microsatellites). Solar

  5. Advanced imaging techniques for assessment of structure, composition and function in biofilm systems. (United States)

    Neu, Thomas R; Manz, Bertram; Volke, Frank; Dynes, James J; Hitchcock, Adam P; Lawrence, John R


    Scientific imaging represents an important and accepted research tool for the analysis and understanding of complex natural systems. Apart from traditional microscopic techniques such as light and electron microscopy, new advanced techniques have been established including laser scanning microscopy (LSM), magnetic resonance imaging (MRI) and scanning transmission X-ray microscopy (STXM). These new techniques allow in situ analysis of the structure, composition, processes and dynamics of microbial communities. The three techniques open up quantitative analytical imaging possibilities that were, until a few years ago, impossible. The microscopic techniques represent powerful tools for examination of mixed environmental microbial communities usually encountered in the form of aggregates and films. As a consequence, LSM, MRI and STXM are being used in order to study complex microbial biofilm systems. This mini review provides a short outline of the more recent applications with the intention to stimulate new research and imaging approaches in microbiology.

  6. Characteristics of sandwich-type structural elements built of advanced composite materials from three dimensional fabrics

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    Castejón, L.


    Full Text Available Sandwich-type structures have proved to be alternatives of great success for several fields of application, and specially in the building sector. This is due to their outstanding properties of .specific rigidity and strength against bending loads and other range of advantages like fatigue and impact resistance, attainment of flat and smooth surfaces, high electric and thermal insulation, design versatility and some others. However, traditional sandwich structures present problems like their tendency towards delamination, stress concentrations in bores or screwed Joints, and pre resistance. These problems are alleviated thanks to the use of new sandwich structures built using three dimensional structures of advanced composite materials, maintaining the present advantages for more traditional sandwich structures. At this rate, these new structures can be applied in several areas where conventional sandwich structures used to be like walls, partitions, floor and ceiling structures, domes, vaults and dwellings, but with greater success.

    Las estructuras tipo sándwich han demostrado ser alternativas de gran éxito para diversos campos de aplicación y, en concreto, en el sector de la construcción, listo es gracias a sus excelentes propiedades de rigidez y resistencia específica frente a cargas de flexión y otra larga lista de ventajas, a la que pertenecen, por ejemplo, su buena resistencia a fatiga, resistencia al impacto, obtención de superficies lisas y suaves, elevado aislamiento térmico y eléctrico, versatilidad de diseño y otras. Sin embargo, las estructuras sándwich, tradicionales presentan una problemática consistente en su tendencia a la delaminación, concentraciones de tensiones ¿aparecidas ante la existencia de agujeros o uniones atornilladas y resistencia al fuego. Estos problemas son pifiados gracias a la aplicación de estructuras novedosas tipo sándwich, construidas a partir de tejidos tridimensionales de materiales

  7. ISAAC Advanced Composites Research Testbed (United States)

    Wu, K. Chauncey; Stewart, Brian K.; Martin, Robert A.


    The NASA Langley Research Center is acquiring a state-of-art composites fabrication capability to support the Center's advanced research and technology mission. The system introduced in this paper is named ISAAC (Integrated Structural Assembly of Advanced Composites). The initial operational capability of ISAAC is automated fiber placement, built around a commercial system from Electroimpact, Inc. that consists of a multi-degree of freedom robot platform, a tool changer mechanism, and a purpose-built fiber placement end effector. Examples are presented of the advanced materials, structures, structural concepts, fabrication processes and technology development that may be enabled using the ISAAC system. The fiber placement end effector may be used directly or with appropriate modifications for these studies, or other end effectors with different capabilities may either be bought or developed with NASA's partners in industry and academia.

  8. Effect of interface structure on mechanical properties of advanced composite materials. (United States)

    Gan, Yong X


    This paper deals with the effect of interface structures on the mechanical properties of fiber reinforced composite materials. First, the background of research, development and applications on hybrid composite materials is introduced. Second, metal/polymer composite bonded structures are discussed. Then, the rationale is given for nanostructuring the interface in composite materials and structures by introducing nanoscale features such as nanopores and nanofibers. The effects of modifying matrices and nano-architecturing interfaces on the mechanical properties of nanocomposite materials are examined. A nonlinear damage model for characterizing the deformation behavior of polymeric nanocomposites is presented and the application of this model to carbon nanotube-reinforced and reactive graphite nanotube-reinforced epoxy composite materials is shown.

  9. Resin Flow of an Advanced Grid-Stiffened Composite Structure in the Co-Curing Process (United States)

    Huang, Qizhong; Ren, Mingfa; Chen, Haoran


    The soft-mold aided co-curing process which cures the skin part and ribs part simultaneously was introduced for reducing the cost of advanced grid-stiffened composite structure (AGS). The co-curing process for a typical AGS, preformed by the prepreg AS4/3501-6, was simulated by a finite element program incorporated with the user-subroutines `thermo-chemical' module and the `chemical-flow' module. The variations of temperature, cure degree, resin pressure and fiber volume fraction of the AGS were predicted. It shows that the uniform distributions of temperature, cure degree and viscosity in the AGS would be disturbed by the unique geometrical pattern of AGS. There is an alternation in distribution of resin pressure at the interface between ribs and skin, and the duration time of resin flow is sensitive to the thickness of the AGS. To obtain a desired AGS, the process parameters of the co-curing process should be determined by the geometry of an AGS and the kinds of resin.

  10. Study on utilization of advanced composites in commercial aircraft wing structures, volume 2 (United States)

    Sakata, I. F.; Ostrom, R. B.


    A plan is defined for a composite wing development effort which will assist commercial transport manufacturers in reaching a level of technology readiness where the utilization of composite wing structure is a cost competitive option for a new aircraft production plan. The recommended development effort consists of two programs: a joint government/industry material development program and a wing structure development program. Both programs are described in detail.

  11. Advanced composites technology

    Energy Technology Data Exchange (ETDEWEB)

    DeTeresa, S J; Groves, S E; Sanchez, R J


    The development of fiber composite components in next-generation munitions, such as sabots for kinetic energy penetrators and lightweight cases for advanced artillery projectiles, relies on design trade-off studies using validated computer code simulations. We are developing capabilities to determine the failure of advanced fiber composites under multiaxial stresses to critically evaluate three-dimensional failure models and develop new ones if necessary. The effects of superimposed hydrostatic pressure on failure of composites are being investigated using a high-pressure testing system that incorporates several unique features. Several improvements were made to the system this year, and we report on the first tests of both isotropic and fiber composite materials. The preliminary results indicate that pressure has little effect on longitudinal compression strength of unidirectional composites, but issues with obtaining reliable failures in these materials still remain to be resolved. The transverse compression strength was found to be significantly enhanced by pressure, and the trends observed for this property and the longitudinal strength are in agreement with recent models for failure of fiber composites.

  12. Advances in HDS catalysts design: relation between catalyst structure and feed composition

    NARCIS (Netherlands)

    Kagami, Narinobu


    The aim of this work is to propose a better understanding of ultra deep HDS for diesel, to contribute to the development of advanced catalysts. The characterization of catalyst structure was examined by XRD, TPR, TPS and Raman spectroscopy. The ranking of catalytic activities were tested using vario

  13. Innovative fabrication processing of advanced composite materials concepts for primary aircraft structures (United States)

    Kassapoglou, Christos; Dinicola, Al J.; Chou, Jack C.


    The autoclave based THERM-X(sub R) process was evaluated by cocuring complex curved panels with frames and stiffeners. The process was shown to result in composite parts of high quality with good compaction at sharp radius regions and corners of intersecting parts. The structural properties of the postbuckled panels fabricated were found to be equivalent to those of conventionally tooled hand laid-up parts. Significant savings in bagging time over conventional tooling were documented. Structural details such as cocured shear ties and embedded stiffener flanges in the skin were found to suppress failure modes such as failure at corners of intersecting members and skin stiffeners separation.

  14. Lightweight Composite Intertank Structure (United States)

    Mehle, Greg V.


    Report presents results of study for proposed lightweight composite material alternative to present semimonocoque aluminum intertank structure for advanced launch vehicles. Proposed structure integrated assembly of sandwich panels made of laminated epoxy-matrix/carbon-fiber skins, and aluminum honeycomb core.

  15. Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologi (United States)


    Fiber-Reinforced-Foam (FRF) Core Composite Sandwich Panel Concept for Advanced Composites Technologies Project - Preliminary Manufacturing Demonstration Articles for Ares V Payload Shroud Barrel Acreage Structure

  16. High Temperature Advanced Structural Composites. Book 1: Executive Summary and Intermetallic Compounds (United States)


    systems. Both exact and approximate techniques were used. For example, using Dvorak’s discovery of the properties of uniform fields in heterogeneous media ...TiL, strengthens; VAL, it weakens NiLAI*Nf sLmElar reeult9 have been repo0ted for XD 1IAl/Ni 2ATL-Ti, 2composites, by Whittenberger eat al (S]. The...have not been rported. The o•i*-ad Ni3Fe has a L12 strucbms; it exhibits long range order below 5000C and is disotdered at tinor at are above that. hlus

  17. Large-Deformation Curling Actuators Based on Carbon Nanotube Composite: Advanced-Structure Design and Biomimetic Application. (United States)

    Chen, Luzhuo; Weng, Mingcen; Zhou, Zhiwei; Zhou, Yi; Zhang, Lingling; Li, Jiaxin; Huang, Zhigao; Zhang, Wei; Liu, Changhong; Fan, Shoushan


    In recent years, electroactive polymers have been developed as actuator materials. As an important branch of electroactive polymers, electrothermal actuators (ETAs) demonstrate potential applications in the fields of artificial muscles, biomimetic devices, robotics, and so on. Large-shape deformation, low-voltage-driven actuation, and ultrafast fabrication are critical to the development of ETA. However, a simultaneous optimization of all of these advantages has not been realized yet. Practical biomimetic applications are also rare. In this work, we introduce an ultrafast approach to fabricate a curling actuator based on a newly designed carbon nanotube and polymer composite, which completely realizes all of the above required advantages. The actuator shows an ultralarge curling actuation with a curvature greater than 1.0 cm(-1) and bending angle larger than 360°, even curling into a tubular structure. The driving voltage is down to a low voltage of 5 V. The remarkable actuation is attributed not only to the mismatch in the coefficients of thermal expansion but also to the mechanical property changes of materials during temperature change. We also construct an S-shape actuator to show the possibility of building advanced-structure actuators. A weightlifting walking robot is further designed that exhibits a fast-moving motion while lifting a sample heavier than itself, demonstrating promising biomimetic applications.

  18. TTT diagram and phase structure control of 2/4 functional epoxy blends used in advanced composites

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ming; AN Xuefeng; TANG Bangming; YI Xiaosu


    A 2/4 functional epoxy blend system (DGEBA/TGMDA) cured with 4,4'-diamino diphenyl sulphone (DDS) was used as the raw material in this research.Round disk compression mode DMA (dynamic mechanical analyzer) was employed to study the gelation at the different temperatures, and the relationship between gel-time (tgel) and temperature was obtained.The cure kinetics was studied by dynamic DSC (differential scanning calorimetry) analysis,and the parame-ters of the cure reaction were obtained to establish a phenom-enological model.The relationship between glass transition temperature (Tg) and cure degree (α) was analyzed by an iso-thermal plus dynamic DSC method based on the DiBenedetto equation,which gave a mathematical description of Tg as a function of both time and temperature.Characteristic tem- peratures such as Tgo,gelTg and Tg∞ were also determined.The cure degree at gelation turned out to be 0.4539,while the tem-perature at which vitrification line and gel line transected was found to be 70.2℃.The time-temperature-transition (TTT) diagram was plotted based on the work above,which served as a tool for process optimization in the manufacture of advanced composites.A new cure procedure of this practical thermosetting system was extracted from the TTT diagram by prolonging the pre-gel time to restrict the diffusion ability and the flow ability of the solution.The final phase structure was proved by SEM to be ex-situ phase morphology com-pared with the traditional in-situ phase structure by exerting different cure procedures.

  19. Deployable Composite Structures Project (United States)

    National Aeronautics and Space Administration — NASA is seeking innovative structure technologies that will advance expandable modules for orbital and surface based habitats. These secondary structures must...

  20. Custom Machines Advance Composite Manufacturing (United States)


    Here is a brief list of materials that NASA will not be using to construct spacecraft: wood, adobe, fiberglass, bone. While it might be obvious why these materials would not make for safe space travel, they do share a common characteristic with materials that may well be the future foundation of spacecraft design: They all are composites. Formed of two or more unlike materials - such as cellulose and lignin in the case of wood, or glass fibers and plastic resin in the case of fiberglass-composites provide enhanced mechanical and physical properties through the combination of their constituent materials. For this reason, composites are used in everything from buildings, bathtubs, and countertops to boats, racecars, and sports equipment. NASA continually works to develop new materials to enable future space missions - lighter, less expensive materials that can still withstand the extreme demands of space travel. Composites such as carbon fiber materials offer promising solutions in this regard, providing strength and stiffness comparable to metals like aluminum but with less weight, allowing for benefits like better fuel efficiency and simpler propulsion system design. Composites can also be made fatigue tolerant and thermally stable - useful in space where temperatures can swing hundreds of degrees. NASA has recently explored the use of composites for aerospace applications through projects like the Composite Crew Module (CCM), a composite-constructed version of the aluminum-lithium Multipurpose Crew Capsule. The CCM was designed to give NASA engineers a chance to gain valuable experience developing and testing composite aerospace structures.

  1. Advanced composites take a powder

    Energy Technology Data Exchange (ETDEWEB)

    Holty, D.W. (Custom Composite Materials, Inc., Atlanta, GA (United States))


    To a professional chemist with more than 25 years of industrial experience, the world of advanced composites is a fascinating new venue. Here resins and fibers come together in a completely synergistic partnership, achieving marvels of strength and light weight that make advanced composite materials virtually the only solution for challenging applications. In the late 1980s, Professor John Muzzy of the Georgia Institute of Technology, was intrigued by the physical properties of thermoplastics, and he developed a new way to bring the thermoplastic resins together with high-performance fibers. As part of the work Muzzy did with Lockheed and NASA he demonstrated that electrostatic powder coating was an attractive new method for combining thermoplastic resins with reinforcing fibers. Presentation of this work by Lockheed at a government-industry conference led to a new project for Muzzy, sponsored by NASA Langley. Powder prepregging proved to be the attractive alternative that NASA was looking for. While working on powder prepregging with LaRC-TPI, Muzzy and his colleagues developed methods for exposing all of the fibers to the powder to improve the distribution of the resin on the tow, a continuous bundle of filaments. Optimal resin distribution was achieved by spreading the moving tow. A very flexible towpreg was produced by maintaining the spread tow through the powder coating chamber and into the oven, where the resin particles were fused to the individual filaments. Muzzy's invention has enabled Custom Composite Materials, Inc. to offer resin/fiber combinations based on thermoplastic resins such as nylon and polypropylene. Beyond the expected advantages over epoxy thermoset systems, they are beginning to exploit a fundamental property of thermoplastic resins: viscoelasticity, which can be defined as the resistance to flow as a function of applied stress. Thermoplastics have a much higher viscoelasticity than thermosets.

  2. Recent Advances on the Understanding of Structural and Composition Evolution of LMR Cathode for Li ion Batteries

    Directory of Open Access Journals (Sweden)

    Pengfei eYan


    Full Text Available Lithium-rich, magnesium-rich (LMR cathode materials have been regarded as very promising for lithium (Li-ion battery applications. However, their practical application is still limited by several barriers such as their limited electrochemical stability and rate capability. In this work, we present recent progress on the understanding of structural and compositional evolution of LMR cathode materials, with an emphasis being placed on the correlation between structural/chemical evolution and electrochemical properties. In particular, using Li[Li0.2Ni0.2Mn0.6]O2 as a typical example, we clearly illustrate the structural characteristics of pristine materials and their dependence on the material-processing history, cycling-induced structural degradation/chemical partition, and their correlation with electrochemical performance degradation. The fundamental understanding that resulted from this work may also guide the design and preparation of new cathode materials based on the ternary system of transitional metal oxides.

  3. Advanced Durability and Damage Tolerance Design and Analysis Methods for Composite Structures: Lessons Learned from NASA Technology Development Programs (United States)

    Harris, Charles E.; Starnes, James H., Jr.; Shuart, Mark J.


    Aerospace vehicles are designed to be durable and damage tolerant. Durability is largely an economic life-cycle design consideration whereas damage tolerance directly addresses the structural airworthiness (safety) of the vehicle. However, both durability and damage tolerance design methodologies must address the deleterious effects of changes in material properties and the initiation and growth of microstructural damage that may occur during the service lifetime of the vehicle. Durability and damage tolerance design and certification requirements are addressed for commercial transport aircraft and NASA manned spacecraft systems. The state-of-the-art in advanced design and analysis methods is illustrated by discussing the results of several recently completed NASA technology development programs. These programs include the NASA Advanced Subsonic Technology Program demonstrating technologies for large transport aircraft and the X-33 hypersonic test vehicle demonstrating technologies for a single-stage-to-orbit space launch vehicle.

  4. Advanced composite materials for optomechanical systems (United States)

    Zweben, Carl


    Polymer matrix composites (PMCs) have been well established in optomechanical systems for several decades. The other three classes of composites; metal matrix composites (MMCs), ceramic matrix composites (CMCs), and carbon matrix composites (CAMCs) are making significant inroads. The latter include carbon/carbon (C/C) composites (CCCs). The success of composites has resulted in increasing use in consumer, industrial, scientific, and aerospace/defense optomechanical applications. Composites offer significant advantages over traditional materials, including high stiffnesses and strengths, near-zero and tailorable coefficients of thermal expansion (CTEs), tailorable thermal conductivities (from very low to over twice that of copper), and low densities. In addition, they lack beryllium's toxicity problems. Some manufacturing processes allow parts consolidation, reducing machining and joining operations. At present, PMCs are the most widely used composites. Optomechanical applications date from the 1970s. The second High Energy Astrophysical Observatory spacecraft, placed in orbit in 1978, had an ultrahigh-modulus carbon fiber-reinforced epoxy (carbon/epoxy) optical bench metering structure. Since then, fibers and matrix materials have advanced significantly, and use of carbon fiber-reinforced polymers (CFRPs) has increased steadily. Space system examples include the Hubble Space Telescope metering truss and instrument benches, Upper Atmosphere Research Satellite (UARS), James Webb Space Telescope and many others. Use has spread to airborne applications, such as SOFIA. Perhaps the most impressive CFRP applications are the fifty-four 12m and twelve 7m moveable ground-based ALMA antennas. The other three classes of composites have a number of significant advantages over PMCs, including no moisture absorption or outgassing of organic compounds. CCC and CMC components have flown on a variety of spacecraft. MMCs have been used in space, aircraft, military and industrial

  5. Application of advanced composites in tokamak magnet systems

    Energy Technology Data Exchange (ETDEWEB)

    Long, C. J.


    The use of advanced (high-modulus) composites in superconducting magnets for tokamak fusion reactors is discussed. The most prominent potential application is as the structure in the pulsed poloidal-field coil system, where a significant reduction in eddy currents could be achieved. Present low-temperature data on the advanced composites are reviewed briefly; they are too meager to do more than suggest a broad class of composites for a particular application.

  6. Anatase TiO2@C composites with porous structure as an advanced anode material for Na ion batteries (United States)

    Shi, Xiaodong; Zhang, Zhian; Du, Ke; Lai, Yanqing; Fang, Jing; Li, Jie


    In this paper, we propose a facile strategy to synthesize the porous structure TiO2@C composites through a two-step method, in which the precursor of MIL-125(Ti) was firstly prepared by solvent thermal method and then calcined under inert atmosphere. When employed as anodes for Na ion batteries, TiO2@C composites can exhibit a superior cyclability with a reversible sodium storage capacity of 148 mAh g-1 at the current density 0.5 A g-1 after 500 cycles and an excellent rate performance with a capacity of 88.9 mAh g-1 even the current reached to 2.5 A g-1 due to the dispersion of anatase TiO2 throughout amorphous carbon matrix and the synergistic effect between the anatase TiO2 nanocrystals and carbon matrix, which can availably enhance the electric conductivity and alleviate the volumetric variation of TiO2 during the insertion/extraction process of Na+.

  7. Advanced X-Ray Inspection of Reinforced Carbon Composite Materials on the Orbiter Leading Edge Structural Subsystem (LESS) (United States)

    Hernandez, Jose M.; Berry, Robert F.; Osborn, Robin; Bueno, Clifford; Osterlitz, Mark; Mills, Richard; Morris, Philip; Phalen, Robert; McNab, Jim; Thibodeaux, Tahanie; Thompson, Kyle


    The post return-to-flight (RTF) inspection methodology for the Orbiter Leading Edge Structural Subsystem (LESS) is currently being defined. Numerous NDT modalities and techniques are being explored to perform the flight-to-flight inspections of the reinforced carbon/carbon (RCC) composite material for impact damage, general loss of mass in the bulk layers, or other anomalous conditions that would pose risk to safe return upon re-entry. It is possible to have an impact upon ascent that is not visually observable on the surface, yet causes internal damage. Radiographic testing may be a useful NDT technique for such occurrences. The authors have performed radiographic tests on full-sized mock samples of LESS hardware with embedded image quality phantoms. Digitized radiographic film, computed radiography and flat panel digital real-time radiography was acquired using a GE Eresco 200 x-ray tube, and Se-75 and Yb-169 radioisotopes.

  8. Deployable Composite Structures Project (United States)

    National Aeronautics and Space Administration — NASA is seeking innovative structure technologies that will advance expandable exploration space modules and surface based habitats. To address this need CTD has...

  9. Research and Development Progress of National Key Laboratory of Advanced Composites on Advanced Aeronautical Resin Matrix Composites

    Directory of Open Access Journals (Sweden)

    LI Bintai


    Full Text Available Applications and research progress in advanced aeronautical resin matrix composites by National Key Laboratory of Advanced Composites (LAC were summarized. A novel interlaminar toughening technology employing ultra-thin TP non-woven fabric was developed in LAC, which significantly improved the compression after impact (CAI performances of composite laminates.Newly designed multilayer sandwich stealth composite structures exhibited a good broadband radar absorbing properties at 1-18 GHz.There were remarkable developments in high toughness and high temperature resin matrix composites, covering major composite processing technologies such as prepreg-autoclave procedure, liquid composite molding and automation manufacture, etc. Finally, numerical simulation and optimization methods were deliberately utilized in the study of composites curing behavior, resin flow and curing deformation. A composite material database was also established.In conclusion, LAC has been a great support for the development of aeronautical equipment, playing such roles as innovation leading, system dominating, foundation supporting and application ensuring of aerocomposites.

  10. Some Lower Valence Vanadium Fluorides: Their Crystal Distortions, Domain Structures, Modulated Structures, Ferrimagnetism, and Composition Dependence. (United States)

    Hong, Y. S.; And Others


    Describes some contemporary concepts unique to the structure of advanced solids, i.e., their crystal distortions, domain structures, modulated structures, ferrimagnetism, and composition dependence. (Author/CS)

  11. Repairs of composite structures (United States)

    Roh, Hee Seok

    Repair on damaged composite panels was conducted. To better understand adhesively bonded repair, the study investigates the effect of design parameters on the joint strength. The design parameters include bondline length, thickness of adherend and type of adhesive. Adhesives considered in this study were tested to measure their tensile material properties. Three types of adhesively bonded joints, single strap, double strap, and single lap joint were considered under changing bondline lengths, thickness of adherend and type of adhesive. Based on lessons learned from bonded joints, a one-sided patch repair method for composite structures was conducted. The composite patch was bonded to the damaged panel by either film adhesive FM-73M or paste adhesive EA-9394 and the residual strengths of the repaired specimens were compared under varying patch sizes. A new repair method using attachments has been suggested to enhance the residual strength. Results obtained through experiments were analyzed using finite element analysis to provide a better repair design and explain the experimental results. It was observed that the residual strength of the repaired specimen was affected by patch length. Method for rapid repairs of damaged composite structures was investigated. The damage was represented by a circular hole in a composite laminated plate. Pre-cured composite patches were bonded with a quick-curing commercial adhesive near (rather than over) the hole. Tensile tests were conducted on specimens repaired with various patch geometries. The test results showed that, among the methods investigated, the best repair method restored over 90% of the original strength of an undamaged panel. The interfacial stresses in the adhesive zone for different patches were calculated in order to understand the efficiencies of the designs of these patch repairs. It was found that the composite patch that yielded the best strength had the lowest interfacial peel stress between the patch and

  12. Analysis of composite structural elements

    Directory of Open Access Journals (Sweden)

    A. Baier


    Full Text Available Purpose: The themes of the study are composite structural components. For this purpose have been designed and built several research positions.Design/methodology/approach: Using different structural materials to build new device components requires multiple tests of the components. Research posts were designed in the advanced graphical program CAx Siemens NX 7.5. Analysed samples were made from the glass fibre, aramid and carbon of various weights. Due to the specific use of composite materials it focuses on the elements in the form of plates and flat bars. For the examination of experimental strain gauge technique was used bead, the force sensor and displacement sensor. The experimental methods were compared with computer simulation using the FEM.Findings: The aim of this study was to determine the basic material constants and a comparison of the experimental method and the method of computer simulation.Research limitations/implications: Change the number of layers and how to connect the laminate with the steel plate changes mechanical properties of the structural component.Practical implications: The ultimate result will be knowledge on the different forms of laminates, such as material properties, the stresses in all layers, strain and comparing the results obtained by two methods.Originality/value: The expected outcome of the study will be the composition and method of joining composite laminate with a steel plate to the possible application in the repair and construction of structural elements of freight wagons.

  13. Deployable Soft Composite Structures


    Wei Wang; Hugo Rodrigue; Sung-Hoon Ahn


    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and sim...

  14. Hybrid composite laminate structures (United States)

    Chamis, C. C.; Lark, R. F. (Inventor)


    An invention which relates to laminate structures and specifically to essentially anisotropic fiber composite laminates is described. Metal foils are selectively disposed within the laminate to produce increased resistance to high velocity impact, fracture, surface erosion, and other stresses within the laminate.

  15. Advanced structural inorganic chemistry

    CERN Document Server

    Li, Wai-Kee; Mak, Thomas C W


    An English edition of a textbook based on teaching at the final year undergraduate and graduate level. It presents structure and bonding, generalizations of structural trends, crystallographic data, as well as highlights from the recent literature.

  16. Unibody Composite Pressurized Structure (United States)

    Rufer, Markus; Conger, Robert; Bauer, Thomas; Newman, John


    An integrated, generic unibody composite pressurized structure (UCPS) combined with a positive expulsion device (PED), consisting of an elastomeric bladder for monopropellant hydrazine, has been quasi-standardized for spacecraft use. The combination functions as an all-composite, non-metallic, propellant tank with bladder. The integrated UCPS combines several previous innovations - specifically, the linerless, all-composite cryogenic tank technology; all-composite boss; resin formulation; and integrated stringer system. The innovation combines the UCPS with an integrated propellant management device (PMD), the PED or bladder, to create an entirely unique system for in-space use. The UCPS is a pressure vessel that incorporates skirts, stringers, and other structures so that it is both an in-space hydrazine tank, and also a structural support system for a spacecraft in a single, all-composite unit. This innovation builds on the progress in the development of a previous SBIR (Small Business Innovation Research) Phase I with Glenn Research Center and an SBIR III with Johnson Space Center that included the fabrication of two 42-in. (˜107-cm) diameter all-composite cryogenic (LOX and liquid methane) UCPS test tanks for a lunar lander. This Phase II provides hydra zine compatibility testing of the elastomeric bladder, a see-through PED to validate the expulsion process and model, and a complete UCPS-based PED with stringers and skirts that will be used to conduct initial qualification and expulsion tests. This extends the UCPS technology to include hydrazine-based, in-space pro - pulsion applications and can also be used for electric propulsion. This innovation creates a system that, in comparison to the traditional approach, is lower in weight, cost, volume, and production time; is stronger; and is capable of much higher pressures. It also has fewer failure modes, and is applicable to both chemical and electric propulsion systems.

  17. Deployable Soft Composite Structures. (United States)

    Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon


    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel.

  18. Deployable Soft Composite Structures (United States)

    Wang, Wei; Rodrigue, Hugo; Ahn, Sung-Hoon


    Deployable structure composed of smart materials based actuators can reconcile its inherently conflicting requirements of low mass, good shape adaptability, and high load-bearing capability. This work describes the fabrication of deployable structures using smart soft composite actuators combining a soft matrix with variable stiffness properties and hinge-like movement through a rigid skeleton. The hinge actuator has the advantage of being simple to fabricate, inexpensive, lightweight and simple to actuate. This basic actuator can then be used to form modules capable of different types of deformations, which can then be assembled into deployable structures. The design of deployable structures is based on three principles: design of basic hinge actuators, assembly of modules and assembly of modules into large-scale deployable structures. Various deployable structures such as a segmented triangular mast, a planar structure comprised of single-loop hexagonal modules and a ring structure comprised of single-loop quadrilateral modules were designed and fabricated to verify this approach. Finally, a prototype for a deployable mirror was developed by attaching a foldable reflective membrane to the designed ring structure and its functionality was tested by using it to reflect sunlight onto to a small-scale solar panel.

  19. Advanced Single-Polymer Nanofiber-Reinforced Composite - Towards Next Generation Ultralight Superstrong/Tough Structural Material (United States)


    and cheaper than synthesis and processing of carbon nanotubes ; issues with stress transfer and imperfect structure of CNT fibers and yarns continue Spider silk is one natural material providing exceptionally high toughness at high strength. In addition, several recent carbon nanotube ...continuous nanofibers in this study outperformed most existing and developmental carbon nanotube - based fibers in terms of toughness. The best recorded

  20. Boron/aluminum graphite/resin advanced fiber composite hybrids (United States)

    Chamis, C. C.; Lark, R. F.; Sullivan, T. L.


    Fabrication feasibility and potential of an adhesively bonded metal and resin matrix fiber-composite hybrid are determined as an advanced material for aerospace and other structural applications. The results show that using this hybrid concept makes possible a composite design which, when compared with nonhybrid composites, has greater transverse strength, transverse stiffness, and impact resistance with only a small penalty on density and longitudinal properties. The results also show that laminate theory is suitable for predicting the structural response of such hybrids. The sequence of fracture modes indicates that these types of hybrids can be readily designed to meet fail-safe requirements.

  1. English 341: Advanced Composition for Teachers (United States)

    Duffy, William


    English 341: Advanced Composition for Teachers is a three-credit undergraduate course for pre-service educators at Francis Marion University, a mid-size public university located in northeast South Carolina. According to the university catalog, students enrolled in English 341 "explore connections among writing, teaching, and learning as they…

  2. Bonded and Stitched Composite Structure (United States)

    Zalewski, Bart F. (Inventor); Dial, William B. (Inventor)


    A method of forming a composite structure can include providing a plurality of composite panels of material, each composite panel having a plurality of holes extending through the panel. An adhesive layer is applied to each composite panel and a adjoining layer is applied over the adhesive layer. The method also includes stitching the composite panels, adhesive layer, and adjoining layer together by passing a length of a flexible connecting element into the plurality of holes in the composite panels of material. At least the adhesive layer is cured to bond the composite panels together and thereby form the composite structure.

  3. Multifunctional Composite Structures (United States)


    1  I.  INTRODUCTION ...create  the model  is significantly  lower because structured  mesh generation is easily automated.         3 I. INTRODUCTION Composite  materials...specialized materials  such  as  piezoelectric  and  magnetostrictive  materials  that  have  been used to design and build both actuators and sensors

  4. Adaptive, tolerant and efficient composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Wiedemann, Martin; Sinapius, Michael (eds.) [German Aerospace Center DLR, Braunschweig (Germany). Inst. of Composite Structures and Adaptive Systems


    Polymer composites offer the possibility for functional integration since the material is produced simultaneously with the product. The efficiency of composite structures raises through functional integration. The specific production processes of composites offer the possibility to improve and to integrate more functions thus making the structure more valuable. Passive functions can be improved by combination of different materials from nano to macro scale, i.e. strength, toughness, bearing strength, compression after impact properties or production tolerances. Active functions can be realized by smart materials, i.e. morphing, active vibration control, active structure acoustic control or structure health monitoring. The basis is a comprehensive understanding of materials, simulation, design methods, production technologies and adaptronics. These disciplines together deliver advanced lightweight solutions for applications ranging from mechanical engineering to vehicles, airframe and space structures along the complete process chain. The book provides basics as well as inspiring ideas for engineers working in the field of adaptive, tolerant and robust composite structures.

  5. Predicting the Structural Performance of Composite Structures Under Cyclic Loading

    NARCIS (Netherlands)

    Kassapoglou, C.


    The increased use of advanced composite materials on primary aircraft structure has brought back to the forefront the question of how such structures perform under repeated loading. In particular, when damage or other stress risers are present, tests have shown that the load to cause failure after

  6. Advanced resin systems for graphite epoxy composites (United States)

    Gilwee, W. J.; Jayarajan, A.


    The value of resin/carbon fiber composites as lightweight structures for aircraft and other vehicle applications is dependent on many properties: environmental stability, strength, toughness, resistance to burning, smoke produced when burning, raw material costs, and complexity of processing. A number of woven carbon fiber and epoxy resin composites were made. The epoxy resin was commercially available tetraglycidylmethylene dianiline. In addition, composites were made using epoxy resin modified with amine and carboxyl terminated butadiene acrylonitrile copolymer. Strength and toughness in flexure as well as oxygen index flammability and NBS smoke chamber tests of the composites are reported.

  7. Large floating structures technological advances

    CERN Document Server

    Wang, BT


    This book surveys key projects that have seen the construction of large floating structures or have attained detailed conceptual designs. This compilation of key floating structures in a single volume captures the innovative features that mark the technological advances made in this field of engineering, and will provide a useful reference for ideas, analysis, design, and construction of these unique and emerging urban projects to offshore and marine engineers, urban planners, architects and students.

  8. Advanced composite elevator for Boeing 727 aircraft (United States)


    Detail design activities are reported for a program to develop an advanced composites elevator for the Boeing 727 commercial transport. Design activities include discussion of the full scale ground test and flight test activities, the ancillary test programs, sustaining efforts, weight status, and the production status. Prior to flight testing of the advanced composites elevator, ground, flight flutter, and stability and control test plans were reviewed and approved by the FAA. Both the ground test and the flight test were conducted according to the approved plan, and were witnessed by the FAA. Three and one half shipsets have now been fabricated without any significant difficulty being encountered. Two elevator system shipsets were weighed, and results validated the 26% predicted weight reduction. The program is on schedule.

  9. Advanced powder metallurgy aluminum alloys and composites (United States)

    Lisagor, W. B.; Stein, B. A.


    The differences between powder and ingot metallurgy processing of aluminum alloys are outlined. The potential payoff in the use of advanced powder metallurgy (PM) aluminum alloys in future transport aircraft is indicated. The national program to bring this technology to commercial fruition and the NASA Langley Research Center role in this program are briefly outlined. Some initial results of research in 2000-series PM alloys and composites that highlight the property improvements possible are given.

  10. Progressive Failure Analysis of Advanced Composites (United States)


    NASA – Langley Research Center 1 Joan Andreu Mayugo University of Girona 1 2 Contents 1 Introduction 11 2 UVARM subroutine 13 2.1 Overview...32] Turon A, Camanho PP, Costa J, Dávila CG. A damage model for the simulation of delamination in advanced composites under variable- mode loading...conference, New York, 1960. p. 63–78. [34] Turon A, Dávila CG, Camanho PP, Costa J. An engineering solution for using coarse meshes in the

  11. Adaptive, tolerant and efficient composite structures

    CERN Document Server

    Sinapius, Michael


    Polymer composites offer the possibility for functional integration since the material is produced simultaneously with the product. The efficiency of composite structures raises through functional integration. The specific production processes of composites offer the possibility to improve and to integrate more functions thus making the structure more valuable. Passive functions can be improved by combination of different materials from nano to macro scale, i.e. strength, toughness, bearing strength, compression after impact properties or production tolerances.  Active functions can be realized by smart materials, i.e. morphing, active vibration control, active structure acoustic control or structure health monitoring. The basis is a comprehensive understanding of materials, simulation, design methods, production technologies and adaptronics. These disciplines together deliver advanced lightweight solutions for applications ranging from mechanical engineering to vehicles, airframe and space structures along ...

  12. Creep rupture behavior of unidirectional advanced composites (United States)

    Yeow, Y. T.


    A 'material modeling' methodology for predicting the creep rupture behavior of unidirectional advanced composites is proposed. In this approach the parameters (obtained from short-term tests) required to make the predictions are the three principal creep compliance master curves and their corresponding quasi-static strengths tested at room temperature (22 C). Using these parameters in conjunction with a failure criterion, creep rupture envelopes can be generated for any combination of in-plane loading conditions and ambient temperature. The analysis was validated experimentally for one composite system, the T300/934 graphite-epoxy system. This was done by performing short-term creep tests (to generate the principal creep compliance master curves with the time-temperature superposition principle) and relatively long-term creep rupture tensile tests of off-axis specimens at 180 C. Good to reasonable agreement between experimental and analytical results is observed.

  13. Boron/aluminum-graphite/resin advanced fiber composite hybrids (United States)

    Chamis, C. C.; Lark, R. F.; Sullivan, T. L.


    An investigation was conducted to determine the fabrication feasibility and to assess the potential of adhesively-bonded metal and resin matrix fiber composite hybrids as an advanced material, for aerospace and other structural applications. The results of fabrication studies and of evaluation of physical and mechanical properties show that using this hybrid concept it is possible to design a composite which, when compared to nonhybrid composites, has improved transverse strength, transverse stiffness, and impact resistance with only a small penalty on density and longitudinal properties. The results also show that laminate theory is suitable for perdicting the structural response of such hybrids. The sequence of fracture modes indicates that these types of hybrids can be readily designed to meet fail-safe requirements.

  14. Combustible structural composites and methods of forming combustible structural composites (United States)

    Daniels, Michael A.; Heaps, Ronald J.; Steffler, Eric D; Swank, William D.


    Combustible structural composites and methods of forming same are disclosed. In an embodiment, a combustible structural composite includes combustible material comprising a fuel metal and a metal oxide. The fuel metal is present in the combustible material at a weight ratio from 1:9 to 1:1 of the fuel metal to the metal oxide. The fuel metal and the metal oxide are capable of exothermically reacting upon application of energy at or above a threshold value to support self-sustaining combustion of the combustible material within the combustible structural composite. Structural-reinforcing fibers are present in the composite at a weight ratio from 1:20 to 10:1 of the structural-reinforcing fibers to the combustible material. Other embodiments and aspects are disclosed.

  15. Precision Composite Space Structures (United States)


    and shear failures ar matrix failure. Out-of-plane shear and norma e l stresses are used when delamination is included. ome degradation models avoid...variation of the norma lamina modulus ith increasing crack density corresponding to the laminate test cases defined in Fig. 42. Fig. 44 and Fig. 45...and Reifsnider KL, (1982), Stiffness-Reduction Mechanisms in Composite P 775, K. L. Reifsnider, Ed., ALaminates,” Damage in Composite Materials. ASTM

  16. Advanced Composites for Air and Ground Vehicles (United States)


    Characterization of Flexural Behavior of Vacuum-Assisted Resin Transfer Molding ( VARTM )-Infused Composite Sandwich Structures 105 9.1.1 Summary 105 9.1.2...the unit cell ......101 Fig. 9.1.1 Layup for the VARTM process .........................................................107 Fig. 9.1.2 a) 3...126 Fig. 9.2.3 VARTM setup ...................................................................................126 Fig. 9.2.4 RTM setup

  17. Field-structured composite studies.

    Energy Technology Data Exchange (ETDEWEB)

    Martin, James Ellis; Williamson, Rodney L.


    Field-structured composites (FSCs) were produced by hosting micron-sized gold-coated nickel particles in a pre-polymer and allowing the mixture to cure in a magnetic field environment. The feasibility of controlling a composite's electrical conductivity using feedback control applied to the field coils was investigated. It was discovered that conductivity in FSCs is primarily determined by stresses in the polymer host matrix due to cure shrinkage. Thus, in cases where the structuring field was uniform and unidirectional so as to produce chainlike structures in the composite, no electrical conductivity was measured until well after the structuring field was turned off at the gel point. In situations where complex, rotating fields were used to generate complex, three-dimensional structures in a composite, very small, but measurable, conductivity was observed prior to the gel point. Responsive, sensitive prototype chemical sensors were developed based on this technology with initial tests showing very promising results.

  18. Quantitative NDE of Composite Structures at NASA (United States)

    Cramer, K. Elliott; Leckey, Cara A. C.; Howell, Patricia A.; Johnston, Patrick H.; Burke, Eric R.; Zalameda, Joseph N.; Winfree, William P.; Seebo, Jeffery P.


    The use of composite materials continues to increase in the aerospace community due to the potential benefits of reduced weight, increased strength, and manufacturability. Ongoing work at NASA involves the use of the large-scale composite structures for spacecraft (payload shrouds, cryotanks, crew modules, etc). NASA is also working to enable the use and certification of composites in aircraft structures through the Advanced Composites Project (ACP). The rapid, in situ characterization of a wide range of the composite materials and structures has become a critical concern for the industry. In many applications it is necessary to monitor changes in these materials over a long time. The quantitative characterization of composite defects such as fiber waviness, reduced bond strength, delamination damage, and microcracking are of particular interest. The research approaches of NASA's Nondestructive Evaluation Sciences Branch include investigation of conventional, guided wave, and phase sensitive ultrasonic methods, infrared thermography and x-ray computed tomography techniques. The use of simulation tools for optimizing and developing these methods is also an active area of research. This paper will focus on current research activities related to large area NDE for rapidly characterizing aerospace composites.

  19. Cradle-to-Grave Monitoring of Composite Aircraft Structures Project (United States)

    National Aeronautics and Space Administration — NextGen is proposing a simple yet powerful damage identification technique for advanced composite structures. We propose to develop a damage index based on vibration...

  20. Technology Assessment of Advanced Composites. Phase 1 (United States)


    Inter-agency funding of pilot demonstration programs for beneficial applications of composites , with a parallel aggressive publication program; such...Letter SUBTECT Composites applications to automobiles Low cost hybrid composites in rotating machinery Sporting goods applications of composites Analysis

  1. Optimization of Laminated Composite Structures

    DEFF Research Database (Denmark)

    Henrichsen, Søren Randrup

    Laminated composite materials are widely used in the design of light weight high performance structures like wind turbine blades and aeroplanes due to their superior stiffness and strength-to-weight-ratios compared to their metal counter parts. Furthermore, the use of laminated composite materials...... allows for a higher degree of tailoring of the resulting material. To enable better utilization of the composite materials, optimum design procedures can be used to assist the engineer. This PhD thesis is focused on developing numerical methods for optimization of laminated composite structures....... The first part of the thesis is intended as an aid to read the included papers. Initially the field of research is introduced and the performed research is motivated. Secondly, the state-of-the-art is reviewed. The review includes parameterizations of the constitutive properties, linear and geometrically...

  2. Composite Tissue Transplantation: A Rapidly Advancing Field (United States)

    Ravindra, K.V.; Wu, S.; Bozulic, L.; Xu, H.; Breidenbach, W.C.; Ildstad, S.T.


    Composite tissue allotransplantation (CTA) is emerging as a potential treatment for complex tissue defects. It is currently being performed with increasing frequency in the clinic. The feasibility of the procedure has been confirmed through 30 hand transplantation, 3 facial reconstructions, and vascularized knee, esophageal, and tracheal allografts. A major drawback for CTA is the requirement for lifelong immunosuppression. The toxicity of these agents has limited the widespread application of CTA. Methods to reduce or eliminate the requirement for immunosuppression and promote CTA acceptance would represent a significant step forward in the field. Multiple studies suggest that mixed chimerism established by bone marrow transplantation promotes tolerance resulting in allograft acceptance. This overview focuses on the history and the exponentially expanding applications of the new frontier in CTA transplantation: immunology associated with CTA; preclinical animal models of CTA; clinical experience with CTA; and advances in mixed chimerism–induced tolerance in CTA. Additionally, some important hurdles that must be overcome in using bone marrow chimerism to induce tolerance to CTA are also discussed. PMID:18589081

  3. Thick-walled carbon composite multifunctional structures (United States)

    Haake, John M.; Jacobs, Jack H.; McIlroy, Bruce E.


    Satellite programs are moving in the direction of smaller and lighter structures. Technological advances have permitted more sophisticated equipment to be consolidated into compact spaces. Micro-satellites, between 10 and 100 kg, will incorporate micro-electric devices into the lay-up of the satellite structure. These structures will be designed to carry load, provide thermal control, enhance damping, and include integrated passive electronics. These multifunctional structures offer lighter weight, reduced volume, and a 'smarter' overall package for incorporation of sensors, electronics, fiber optics, powered appendages or active components. McDonnell Douglas Corporation (MDC) has applied technology from the synthesis and processing of intelligent cost effective structures (SPICES) and independent research and development (IRAD) programs to the modular instrument support system (MISS) for multifunctional space structures and micro-satellites. The SPICES program was funded by the Defense Advanced Research Projects Agency (DARPA) to develop affordable manufacturing processes for smart materials to be used in vibration control, and the MISS program was funded by NASA-Langley. The MISS program was conceived to develop concepts and techniques to make connections between different multifunctional structures. MDA fabricated a trapezoidal carbon composite structure out of IM7/977-3 tape prepreg. Flex circuits, thermal and optical conduits were embedded to realize a utility modular connector. These provide electrical, thermal, optical and mechanical connections between micro- satellite components. A quick disconnect mount was also developed to accommodate a variety of devices such as solar arrays, power sources, thermal transfer and vibration control modules.

  4. Structure and composition of soils

    Directory of Open Access Journals (Sweden)

    Snežana Nenadović


    Full Text Available This paper presents a study of soils structure and composition using up to date technique, such as scanning electronic microscopy, atomic force microscopy, X-ray diffraction, X-ray fluorescence, as well as some other characterization methods. It was shown that soil particles have porous structure and dimensions in the range from several millimeters to several hundreds of nanometers and consist of different minerals such as kaolin, quartz and feldspate.

  5. Hybrid Simulation of Composite Structures

    DEFF Research Database (Denmark)

    Høgh, Jacob Herold

    of freedom. In this dissertation the main focus is to develop hybrid simulation for composite structures e.g. wind turbine blades where the boundary between the numerical model and the physical experiment is continues i.e. in principal infinite amount of degrees of freedom. This highly complicates...... at the shared boundary. The hybrid simulation programs have been tested on different simple composite structures and they have proven able to increase the accuracy in tests with a complex transfer system.......Hybrid simulation is a substructural method combining a numerical simulation with a physical experiment. A structure is thereby simulated under the assumption that a substructure’s response is well known and easily modelled while a given substructure is studied more accurately in a physical...

  6. NASTRAN as an analytical research tool for composite mechanics and composite structures (United States)

    Chamis, C. C.; Sinclair, J. H.; Sullivan, T. L.


    Selected examples are described in which NASTRAN is used as an analysis research tool for composite mechanics and for composite structural components. The examples were selected to illustrate the importance of using NASTRAN as an analysis tool in this rapidly advancing field.

  7. Research advance in wood composites in China

    Institute of Scientific and Technical Information of China (English)


    Wood composites can generally be classified in three parts: laminated composites, mixed composites and penetrated composites. Every part has its own characteristic and can be further divided. This paper introduces the history and the state of development of wood composites in China. The research about glue-laminated timber is rare and the industry hardly comes to being. A great of achievements have been obtained in mixed composites and it is well industrialized. Many studies on scrimber have been done and the Chinese researchers are looking for a feasible way to develop the scrimber industry in China. Chinese researchers also spent so much energy in studying wood plastic composites (WPC), but it has not been industrialized due to the high cost.

  8. Lectures on Composite Materials for Aircraft Structures, (United States)


    lectures are related to structural applications of composites . In Lecture 7, the basic theory that is needed for composite structural analysis is...which composites have been taken up for aeronautical applications. Several specific applications of composites in aircraft structures am described in

  9. Fiber reinforced polymer composites for bridge structures

    Directory of Open Access Journals (Sweden)

    Alexandra CANTORIU


    Full Text Available Rapid advances in construction materials technology have led to the emergence of new materials with special properties, aiming at safety, economy and functionality of bridges structures. A class of structural materials which was originally developed many years ago, but recently caught the attention of engineers involved in the construction of bridges is fiber reinforced polymer composites. This paper provides an overview of fiber reinforced polymer composites used in bridge structures including types, properties, applications and future trends. The results of this study have revealed that this class of materials presents outstanding properties such as high specific strength, high fatigue and environmental resistance, lightweight, stiffness, magnetic transparency, highly cost-effective, and quick assembly, but in the same time high initial costs, lack of data on long-term field performance, low fire resistance. Fiber reinforced polymer composites were widely used in construction of different bridge structures such as: deck and tower, I-beams, tendons, cable stands and proved to be materials for future in this field.

  10. Cumulative Damage Model for Advanced Composite Materials. (United States)


    ultimately used an exponential in the present example for added simplicity) and we norma - lize the function so that it becomes the modifier that determines...Testing and Design (Second Conference), ASTM STP 497, ASTM (1972) pp. 170-188. 5. Halpin, J. C., et al., "Characterization of Composites for the...Graphite Epoxy Composites," Proc. Symposium on Composite Materials: Testing and Design, ASTM , (Ma’rch 20, 1978) New Orleans, LA. 18. Hashin, Z. and Rotem

  11. Electron Beam Curing of Advanced Composites

    Institute of Scientific and Technical Information of China (English)


    The fundamental concept of electron beam method and the application in cure of composites are elaborated in this paper. The components of electron beam curing system are introduced. The mechanisms of interaction between electron beam and polymer matrix composites are presented. Recent studies reported including work of authors themselves on electron beam curing of composites are also discussed. Moreover, the authors believe that it is necessary to do the basic research about understanding how electron beam affects cured network and the mechanical/physical properties of the composites, for establishing a quantitative or semi-quantitative formulation.

  12. Advanced thermoplastic composites: An attractive new material for usage in highly loaded vehicle components

    Energy Technology Data Exchange (ETDEWEB)

    Mehn, R.; Seidl, F.; Peis, R.; Heinzmann, D.; Frei, P. [BMW AG Muenchen (Germany)


    Beside the lightweight potential and further well known advantages of advanced composite materials, continuous fiber reinforced thermoplastics employed in vehicle structural parts especially offer short manufacturing cycle times and an additional economically viable manufacturing process. Presenting a frame structure concept for two highly loaded vehicle parts, a safety seat and a side door, numerous features concerning the choice of suitable composite materials, design aspects, investigations to develop a thermoforming technique, mature for a series production of vehicle parts, are discussed.

  13. Deployable truss structure advanced technology (United States)

    Dyer, J. E.; Dudeck, M. P.


    The 5-meter technology antenna program demonstrated the overall feasibility of integrating a mesh reflector surface with a deployable truss structure to achieve a precision surface contour compatible with future, high-performance antenna requirements. Specifically, the program demonstrated: the feasibility of fabricating a precision, edge-mounted, deployable, tetrahedral truss structure; the feasibility of adjusting a truss-supported mesh reflector contour to a surface error less than 10 mils rms; and good RF test performance, which correlated well with analytical predictions. Further analysis and testing (including flight testing) programs are needed to fully verify all the technology issues, including structural dynamics, thermodynamics, control, and on-orbit RF performance, which are associated with large, deployable, truss antenna structures.

  14. Advanced composites for aerospace, marine, and land applications

    CERN Document Server

    Srivatsan, T; Peretti, Michael


    The papers in this volume cover a broad spectrum of topics that represent the truly diverse nature of the field of composite materials. This collection presents research and findings relevant to the latest advances in composites materials, specifically their use in aerospace, maritime, and even land applications. The editors have made every effort to bring together authors who put forth recent advances in their research while concurrently both elaborating on and thereby enhancing our prevailing understanding of the salient aspects related to the science, engineering, and far-reaching technological applications of composite materials.

  15. Electron processing of fibre-reinforced advanced composites (United States)

    Singh, Ajit; Saunders, Chris B.; Barnard, John W.; Lopata, Vince J.; Kremers, Walter; McDougall, Tom E.; Chung, Minda; Tateishi, Miyoko


    Advanced composites, such as carbon-fibre-reinforced epoxies, are used in the aircraft, aerospace, sporting goods, and transportation industries. Though thermal curing is the dominant industrial process for advanced composites, electron curing of similar composites containing acrylated epoxy matrices has been demonstrated by our work. The main attraction of electron processing technology over thermal technology is the advantages it offers which include ambient temperature curing, reduced curing times, reduced volatile emissions, better material handling, and reduced costs. Electron curing technology allows for the curing of many types of products, such as complex shaped, those containing different types of fibres, and up to 15 cm thick. Our work has been done principally with the AECL's 10 MeV, 1 kW electron accelerator; we have also done some comparative work with an AECL Gammacell 220. In this paper we briefly review our work on the various aspects of electron curing of advanced composites and their properties.

  16. Advances in the history of composite resins. (United States)

    Minguez, Nieves; Ellacuria, Joseba; Soler, José Ignacio; Triana, Rodrigo; Ibaseta, Guillermo


    The use of composite resins as direct restoration material in posterior teeth has demonstrated a great increase, due to esthetic requirements and the controversy regarding the mercury content in silver amalgams. In this article, we have reviewed the composition modifications which have occurred in materials based on resins since their introduction over a half a century ago which have enabled great improvements in their physical and mechanical properties. Likewise, we have highlighted current lines of research, centered on finding the ideal material for replacing silver amalgam as a direct filling material.

  17. Structural integrity of hierarchical composites

    Directory of Open Access Journals (Sweden)

    Marco Paggi


    Full Text Available Interface mechanical problems are of paramount importance in engineering and materials science. Traditionally, due to the complexity of modelling their mechanical behaviour, interfaces are often treated as defects and their features are not explored. In this study, a different approach is illustrated, where the interfaces play an active role in the design of innovative hierarchical composites and are fundamental for their structural integrity. Numerical examples regarding cutting tools made of hierarchical cellular polycrystalline materials are proposed, showing that tailoring of interface properties at the different scales is the way to achieve superior mechanical responses that cannot be obtained using standard materials

  18. Structural materials challenges for advanced reactor systems (United States)

    Yvon, P.; Carré, F.


    Key technologies for advanced nuclear systems encompass high temperature structural materials, fast neutron resistant core materials, and specific reactor and power conversion technologies (intermediate heat exchanger, turbo-machinery, high temperature electrolytic or thermo-chemical water splitting processes, etc.). The main requirements for the materials to be used in these reactor systems are dimensional stability under irradiation, whether under stress (irradiation creep or relaxation) or without stress (swelling, growth), an acceptable evolution under ageing of the mechanical properties (tensile strength, ductility, creep resistance, fracture toughness, resilience) and a good behavior in corrosive environments (reactor coolant or process fluid). Other criteria for the materials are their cost to fabricate and to assemble, and their composition could be optimized in order for instance to present low-activation (or rapid desactivation) features which facilitate maintenance and disposal. These requirements have to be met under normal operating conditions, as well as in incidental and accidental conditions. These challenging requirements imply that in most cases, the use of conventional nuclear materials is excluded, even after optimization and a new range of materials has to be developed and qualified for nuclear use. This paper gives a brief overview of various materials that are essential to establish advanced systems feasibility and performance for in pile and out of pile applications, such as ferritic/martensitic steels (9-12% Cr), nickel based alloys (Haynes 230, Inconel 617, etc.), oxide dispersion strengthened ferritic/martensitic steels, and ceramics (SiC, TiC, etc.). This article gives also an insight into the various natures of R&D needed on advanced materials, including fundamental research to investigate basic physical and chemical phenomena occurring in normal and accidental operating conditions, lab-scale tests to characterize candidate materials

  19. Advanced Manufacturing Technologies (AMT): Composites Integrated Modeling Element (United States)

    National Aeronautics and Space Administration — CIM encompassed computational methods, tools and processes that go into the materials, design, manufacturing and qualification of composite aerospace structures....

  20. Hybrid Composite Cryogenic Tank Structure (United States)

    DeLay, Thomas


    A hybrid lightweight composite tank has been created using specially designed materials and manufacturing processes. The tank is produced by using a hybrid structure consisting of at least two reinforced composite material systems. The inner composite layer comprises a distinct fiber and resin matrix suitable for cryogenic use that is a braided-sleeve (and/or a filamentwound layer) aramid fiber preform that is placed on a removable mandrel (outfitted with metallic end fittings) and is infused (vacuum-assisted resin transfer molded) with a polyurethane resin matrix with a high ductility at low temperatures. This inner layer is allowed to cure and is encapsulated with a filamentwound outer composite layer of a distinct fiber resin system. Both inner and outer layer are in intimate contact, and can also be cured at the same time. The outer layer is a material that performs well for low temperature pressure vessels, and it can rely on the inner layer to act as a liner to contain the fluids. The outer layer can be a variety of materials, but the best embodiment may be the use of a continuous tow of carbon fiber (T-1000 carbon, or others), or other high-strength fibers combined with a high ductility epoxy resin matrix, or a polyurethane matrix, which performs well at low temperatures. After curing, the mandrel can be removed from the outer layer. While the hybrid structure is not limited to two particular materials, a preferred version of the tank has been demonstrated on an actual test tank article cycled at high pressures with liquid nitrogen and liquid hydrogen, and the best version is an inner layer of PBO (poly-pphenylenebenzobisoxazole) fibers with a polyurethane matrix and an outer layer of T-1000 carbon with a high elongation epoxy matrix suitable for cryogenic temperatures. A polyurethane matrix has also been used for the outer layer. The construction method is ideal because the fiber and resin of the inner layer has a high strain to failure at cryogenic

  1. Conceptual design study of advanced acoustic-composite nacelles (United States)

    Nordstrom, K. E.; Marsh, A. H.; Sargisson, D. F.


    Conceptual studies were conducted to assess the impact of incorporating advanced technologies in the nacelles of a current wide-bodied transport and an advanced technology transport. The improvement possible in the areas of fuel consumption, flyover noise levels, airplane weight, manufacturing costs, and airplane operating cost were evaluated for short and long-duct nacelles. Use of composite structures for acoustic duct linings in the fan inlet and exhaust ducts was considered as well as for other nacelle components. For the wide-bodied transport, the use of a long-duct nacelle with an internal mixer nozzle in the primary exhaust showed significant improvement in installed specific fuel consumption and airplane direct operating costs compared to the current short-duct nacelle. The long-duct mixed-flow nacelle is expected to achieve significant reductions in jet noise during takeoff and in turbo-machinery noise during landing approach. Recommendations were made of the technology development needed to achieve the potential fuel conservation and noise reduction benefits.

  2. Combustion synthesis of advanced composite materials (United States)

    Moore, John J.


    Self-propagating high temperature (combustion) synthesis (SHS), has been investigated as a means of producing both dense and expanded (foamed) ceramic and ceramic-metal composites, ceramic powders and whiskers. Several model exothermic combustion synthesis reactions were used to establish the importance of certain reaction parameters, e.g., stoichiometry, green density, combustion mode, particle size, etc. on the control of the synthesis reaction, product morphology and properties. The use of an in situ liquid infiltration technique and the effect of varying the reactants and their stoichiometry to provide a range of reactant and product species i.e., solids, liquids and gases, with varying physical properties e.g., volatility and thermal conductivity, on the microstructure and morphology of synthesized composite materials is discussed. Conducting the combustion synthesis reaction in a reactive gas environment to take advantage of the synergistic effects of combustion synthesis and vapor phase transport is also examined.

  3. Composite Tissue Transplantation: A Rapidly Advancing Field


    Ravindra, K.V.; Wu, S.; Bozulic, L.; Xu, H.; Breidenbach, W.C.; Ildstad, S.T.


    Composite tissue allotransplantation (CTA) is emerging as a potential treatment for complex tissue defects. It is currently being performed with increasing frequency in the clinic. The feasibility of the procedure has been confirmed through 30 hand transplantation, 3 facial reconstructions, and vascularized knee, esophageal, and tracheal allografts. A major drawback for CTA is the requirement for lifelong immunosuppression. The toxicity of these agents has limited the widespread application o...

  4. Single crystal piezoelectric composites for advanced NDT ultrasound (United States)

    Jiang, Xiaoning; Snook, Kevin; Hackenberger, Wesley S.; Geng, Xuecang


    In this paper, the design, fabrication and characterization of PMN-PT single crystal/epoxy composites are reported for NDT ultrasound transducers. Specifically, 1-3 PMN-PT/epoxy composites with center frequencies of 5 MHz - 40 MHz were designed and fabricated using either the dice-and-fill method or a photolithography based micromachining process. The measured electromechanical coefficients for composites with frequency of 5 MHz - 15 MHz were about 0.78-0.83, and the coupling coefficients for composites with frequencies of 25 MHz- 40 MHz were about 0.71-0.72. The dielectric loss remains low (advanced NDT ultrasound applications.

  5. Process simulation for advanced composites production

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, M.D.; Ferko, S.M.; Griffiths, S. [Sandia National Labs., Livermore, CA (United States)] [and others


    The objective of this project is to improve the efficiency and lower the cost of chemical vapor deposition (CVD) processes used to manufacture advanced ceramics by providing the physical and chemical understanding necessary to optimize and control these processes. Project deliverables include: numerical process models; databases of thermodynamic and kinetic information related to the deposition process; and process sensors and software algorithms that can be used for process control. Target manufacturing techniques include CVD fiber coating technologies (used to deposit interfacial coatings on continuous fiber ceramic preforms), chemical vapor infiltration, thin-film deposition processes used in the glass industry, and coating techniques used to deposit wear-, abrasion-, and corrosion-resistant coatings for use in the pulp and paper, metals processing, and aluminum industries.

  6. Beam structures classical and advanced theories

    CERN Document Server

    Carrera, Erasmo; Petrolo, Marco


    Beam theories are exploited worldwide to analyze civil, mechanical, automotive, and aerospace structures. Many beam approaches have been proposed during the last centuries by eminent scientists such as Euler, Bernoulli, Navier, Timoshenko, Vlasov, etc.  Most of these models are problem dependent: they provide reliable results for a given problem, for instance a given section and cannot be applied to a different one. Beam Structures: Classical and Advanced Theories proposes a new original unified approach to beam theory that includes practically all classical and advanced models for be

  7. Advances in structure research by diffraction methods

    CERN Document Server

    Brill, R


    Advances in Structure Research by Diffraction Methods reviews advances in the use of diffraction methods in structure research. Topics covered include the dynamical theory of X-ray diffraction, with emphasis on Ewald waves in theory and experiment; dynamical theory of electron diffraction; small angle scattering; and molecular packing. This book is comprised of four chapters and begins with an overview of the dynamical theory of X-ray diffraction, especially in terms of how it explains all the absorption and propagation properties of X-rays at the Bragg setting in a perfect crystal. The next

  8. Advanced composite polymer electrolyte fuel cell membranes

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.S.; Zawodzinski, T.A.; Gottesfeld, S.; Kolde, J.A.; Bahar, B.


    A new type of reinforced composite perfluorinated polymer electrolyte membrane, GORE-SELECT{trademark} (W.L. Gore & Assoc.), is characterized and tested for fuel cell applications. Very thin membranes (5-20 {mu}m thick) are available. The combination of reinforcement and thinness provides high membrane, conductances (80 S/cm{sup 2} for a 12 {mu}m thick membrane at 25{degrees}C) and improved water distribution in the operating fuel cell without sacrificing longevity or durability. In contrast to nonreinforced perfluorinated membranes, the x-y dimensions of the GORE-SELECT membranes are relatively unaffected by the hydration state. This feature may be important from the viewpoints of membrane/electrode interface stability and fuel cell manufacturability.

  9. Processamento de laminados de compósitos poliméricos avançados com bordas moldadas Processing of advanced structural polymeric composite laminates with molded edges

    Directory of Open Access Journals (Sweden)

    Geraldo M. Cândido


    Full Text Available Técnicas que contribuem para melhorar a qualidade dos compósitos produzidos por laminação manual e cura em autoclave e/ou visando à redução no custo de processamento têm sido intensamente pesquisadas. Uma das maneiras de se obter esse ganho de produtividade é eliminar operações de usinagem da borda por meio da técnica de fabricação de laminados com bordas moldadas. Neste trabalho é apresentada uma revisão da tecnologia de fabricação de peças estruturais de compósitos poliméricos avançados, com ênfase na produção de laminados com bordas moldadas. Exemplos deste tipo de acabamento são mostrados utilizando laminados cruzados simétricos [(0,90/0]s e [(0,90/90]s, fabricados com fita unidirecional contínua e tecido bidirecional de carbono, pré-impregnados com resina epóxi. O arranjo de fibras e resina na região da borda livre de todos os corpos-de-prova foi analisado usando um microscópio óptico. Foi observado que as fibras longitudinais (a 0° podem se mover lateralmente na direção da borda moldada sob ação da pressão aplicada durante a cura. Bolsas de resina pura podem ser formadas nessa região dependendo da seqüência de empilhamento do laminado.Manufacturing techniques that improve the quality and/or reduce the cost of advanced composites structures produced by vacuum bag and cure in autoclave have been intensely investigated. One way to obtain a gain in productivity is to produce laminates with molded edges. This work presents a literature review of the fabrication process of structural parts of advanced polymeric composites, with emphasis in the manufacturing of laminates with molded edges. As an example of this type of edge finishing, symmetric cross ply laminates [(0,90/0]s and [(0,90/90]s were manufactured with pre-impregnated unidirectional tape and fabric. The arrangement of fibers and resin near the free edge of all specimens were analyzed using an optical microscope. It was observed that

  10. Multifunctional Composite Nanofibers for Smart Structures (United States)


    translated to the composite nanofibrous structures in the form of nonwovens and yarns? (3) Can these functional composite fibers be integrated into...nanoparticles were co- electrospun into nonwoven mat and over meter long yarn. The SEM and TEM image in Report Documentation Page Form ApprovedOMB No...functional composite nanofiber structures (yarn and nonwoven ) characterized we explored the feasibility of integrating these functional composite fibers into

  11. Forming of shape memory composite structures

    DEFF Research Database (Denmark)

    Santo, Loredana; Quadrini, Fabrizio; De Chiffre, Leonardo


    A new forming procedure was developed to produce shape memory composite structures having structural composite skins over a shape memory polymer core. Core material was obtained by solid state foaming of an epoxy polyester resin with remarkably shape memory properties. The composite skin consisted...... damaging (i.e. after room temperature compression). Compressing the panel at a temperature higher than the foam resin glass transition temperature minimally affects composite stiffness. Copyright © 2013 Trans Tech Publications Ltd....

  12. Advances in very lightweight composite mirror technology (United States)

    Chen, Peter C.; Bowers, Charles W.; Content, David A.; Marzouk, Marzouk; Romeo, Robert C.


    We report progress in the development of very lightweight (roll off and several waves (rms optical) of astigmatism, coma, and third-order spherical aberration. These are indications of thermal contraction in an inhomogeneous medium. This inhomogeneity is due to a systematic radial variation in density and fiber/resin ratio induced in composite plies when draped around a small and highly curved mandrel. The figure accuracy is expected to improve with larger size optics and in mirrors with longer radii of curvature. Nevertheless, the present accuracy figure is sufficient for using postfiguring techniques such as ion milling to achieve diffraction-limited performances at optical and UV wavelengths. We demonstrate active figure control using a simple apparatus of low-mass, low-force actuators to correct astigmatism. The optimized replication technique is applied to the fabrication of a 0.6-m-diam mirror with an areal density of 3.2 kg/m2. Our result demonstrates that the very lightweight, large-aperture construction used in radio telescopes can now be applied to optical telescopes.

  13. Advances in structure research by diffraction methods

    CERN Document Server

    Hoppe, W


    Advances in Structure Research by Diffraction Methods: Volume 5 presents discussions on application of diffraction methods in structure research. The book provides the aspects of structure research using various diffraction methods. The text contains 2 chapters. Chapter 1 reviews the general theory and experimental methods used in the study of all types of amorphous solid, by both X-ray and neutron diffraction, and the detailed bibliography of work on inorganic glasses. The second chapter discusses electron diffraction, one of the major methods of determining the structures of molecules in the

  14. Advanced structural equation modeling issues and techniques

    CERN Document Server

    Marcoulides, George A


    By focusing primarily on the application of structural equation modeling (SEM) techniques in example cases and situations, this book provides an understanding and working knowledge of advanced SEM techniques with a minimum of mathematical derivations. The book was written for a broad audience crossing many disciplines, assumes an understanding of graduate level multivariate statistics, including an introduction to SEM.

  15. Lamb Wave Propagation in Laminated Composite Structures


    Gopalakrishnan, S.


    Damage detection using guided Lamb waves is an important tool in Structural health Monitoring. In this paper, we outline a method of obtaining Lamb wave modes in composite structures using two dimensional Spectral Finite Elements. Using this approach, Lamb wave dispersion curves are obtained for laminated composite structures with different fibre orientation. These propagating Lamb wave modes are pictorially captured using tone burst signal.

  16. Structural applications of Avimid K3B LDF thermoplastic composites (United States)

    Perrella, Andrew P.

    Composite applications on advanced aircraft require lightweight, high performance, tough material systems which are capable of operating at high service temperatures. These composite systems must also be producible and cost effective. Avimid K3B composite materials and related process and part manufacturing technologies offers a unique solutions to these requirements. The objective of this paper is to describe selected Avimid K3B processing approaches such as Long Discontinuous Fiber thermoforming and fusion bonding. A review of the Avimid K3B F-16 Strake Door Joint Development Program is presented. This program successfully developed, built and structurally validated a flight demonstration component using these materials and manufacturing methods.

  17. Polymer, metal, and ceramic matrix composites for advanced aircraft engine applications (United States)

    Mcdanels, D. L.; Serafini, T. T.; Dicarlo, J. A.


    Advanced aircraft engine research within NASA Lewis is being focused on propulsion systems for subsonic, supersonic, and hypersonic aircraft. Each of these flight regimes requires different types of engines, but all require advanced materials to meet their goals of performance, thrust-to-weight ratio, and fuel efficiency. The high strength/weight and stiffness/weight properties of resin, metal, and ceramic matrix composites will play an increasingly key role in meeting these performance requirements. At NASA Lewis, research is ongoing to apply graphite/polyimide composites to engine components and to develop polymer matrices with higher operating temperature capabilities. Metal matrix composites, using magnesium, aluminum, titanium, and superalloy matrices, are being developed for application to static and rotating engine components, as well as for space applications, over a broad temperature range. Ceramic matrix composites are also being examined to increase the toughness and reliability of ceramics for application to high-temperature engine structures and components.

  18. Conceptual study on a new generation of the high-innovative advanced porous and composite nanostructural functional materials with nanofibers


    L.A. Dobrzański; M. Pawlyta; A. Hudecki


    Purpose: The purpose of the paper is to analyse theoretically the possibilities of the development of a new generation of the high-innovative advanced porous and composite nanostructural functional materials with nanofibers and to study into the material science grounds of synthesis and/or production and formulation of such materials’ structure and properties and to characterise and model their structure and properties depending on the compositional, phase and chemical composition and the app...

  19. Composite Materials for Structural Design. (United States)


    Introduction to Composite Materials , Technomic, Westport, Connecticut, 1980, pp. 19-20, 388-401. 8. W.D. Bascom, J.L. Bitner, R.J. Moulton, and A.R. Siebert...34 Introduction to Composite Materials ", Technomic Publishing Co., pp. 8-18,(1980). [6] Beckwith, S. W., "Viscoelastic Characterization of a Nonlinear Glass

  20. Development of Textile Reinforced Composites for Aircraft Structures (United States)

    Dexter, H. Benson


    NASA has been a leader in development of composite materials for aircraft applications during the past 25 years. In the early 1980's NASA and others conducted research to improve damage tolerance of composite structures through the use of toughened resins but these resins were not cost-effective. The aircraft industry wanted affordable, robust structures that could withstand the rigors of flight service with minimal damage. The cost and damage tolerance barriers of conventional laminated composites led NASA to focus on new concepts in composites which would incorporate the automated manufacturing methods of the textiles industry and which would incorporate through-the-thickness reinforcements. The NASA Advanced Composites Technology (ACT) Program provided the resources to extensively investigate the application of textile processes to next generation aircraft wing and fuselage structures. This paper discusses advanced textile material forms that have been developed, innovative machine concepts and key technology advancements required for future application of textile reinforced composites in commercial transport aircraft. Multiaxial warp knitting, triaxial braiding and through-the-thickness stitching are the three textile processes that have surfaced as the most promising for further development. Textile reinforced composite structural elements that have been developed in the NASA ACT Program are discussed. Included are braided fuselage frames and window-belt reinforcements, woven/stitched lower fuselage side panels, stitched multiaxial warp knit wing skins, and braided wing stiffeners. In addition, low-cost processing concepts such as resin transfer molding (RTM), resin film infusion (RFI), and vacuum-assisted resin transfer molding (VARTM) are discussed. Process modeling concepts to predict resin flow and cure in textile preforms are also discussed.

  1. Overview of bacterial cellulose composites: a multipurpose advanced material. (United States)

    Shah, Nasrullah; Ul-Islam, Mazhar; Khattak, Waleed Ahmad; Park, Joong Kon


    Bacterial cellulose (BC) has received substantial interest owing to its unique structural features and impressive physico-mechanical properties. BC has a variety of applications in biomedical fields, including use as biomaterial for artificial skin, artificial blood vessels, vascular grafts, scaffolds for tissue engineering, and wound dressing. However, pristine BC lacks certain properties, which limits its applications in various fields; therefore, synthesis of BC composites has been conducted to address these limitations. A variety of BC composite synthetic strategies have been developed based on the nature and relevant applications of the combined materials. BC composites are primarily synthesized through in situ addition of reinforcement materials to BC synthetic media or the ex situ penetration of such materials into BC microfibrils. Polymer blending and solution mixing are less frequently used synthetic approaches. BC composites have been synthesized using numerous materials ranging from organic polymers to inorganic nanoparticles. In medical fields, these composites are used for tissue regeneration, healing of deep wounds, enzyme immobilization, and synthesis of medical devices that could replace cardiovascular and other connective tissues. Various electrical products, including biosensors, biocatalysts, E-papers, display devices, electrical instruments, and optoelectronic devices, are prepared from BC composites with conductive materials. In this review, we compiled various synthetic approaches for BC composite synthesis, classes of BC composites, and applications of BC composites. This study will increase interest in BC composites and the development of new ideas in this field.

  2. Thermomechanics of composite structures under high temperatures

    CERN Document Server

    Dimitrienko, Yu I


    This pioneering book presents new models for the thermomechanical behavior of composite materials and structures taking into account internal physico-chemical transformations such as thermodecomposition, sublimation and melting at high temperatures (up to 3000 K). It is of great importance for the design of new thermostable materials and for the investigation of reliability and fire safety of composite structures. It also supports the investigation of interaction of composites with laser irradiation and the design of heat-shield systems. Structural methods are presented for calculating the effective mechanical and thermal properties of matrices, fibres and unidirectional, reinforced by dispersed particles and textile composites, in terms of properties of their constituent phases. Useful calculation methods are developed for characteristics such as the rate of thermomechanical erosion of composites under high-speed flow and the heat deformation of composites with account of chemical shrinkage. The author expan...

  3. Creep of Structural Nuclear Composites

    Energy Technology Data Exchange (ETDEWEB)

    Will Windes; R.W. Lloyd


    A research program has been established to investigate fiber reinforced ceramic composites to be used as control rod components within a Very High Temperature Reactor (VHTR) design. Two candidate systems have been identified, carbon fiber reinforced carbon (Cf/C) and silicon carbide fiber reinforced silicon carbide (SiCf/SiC) composites. One of the primary degradation mechanisms anticipated for these core components is high temperature thermal and irradiation enhanced creep. As a consequence, high temperature test equipment, testing methodologies, and test samples for very high temperature (up to 1600º C) tensile strength and long duration creep studies have been established. Actual testing of both tubular and flat, "dog-bone"-shaped tensile composite specimens will begin next year. Since there is no precedence for using ceramic composites within a nuclear reactor, ASTM standard test procedures are currently being established from these high temperature mechanical tests.

  4. Review on advanced composite materials boring mechanism and tools (United States)

    Shi, Runping; Wang, Chengyong


    With the rapid development of aviation and aerospace manufacturing technology, advanced composite materials represented by carbon fibre reinforced plastics (CFRP) and super hybrid composites (fibre/metal plates) are more and more widely applied. The fibres are mainly carbon fibre, boron fibre, Aramid fiber and Sic fibre. The matrixes are resin matrix, metal matrix and ceramic matrix. Advanced composite materials have higher specific strength and higher specific modulus than glass fibre reinforced resin composites of the 1st generation. They are widely used in aviation and aerospace industry due to their high specific strength, high specific modulus, excellent ductility, anticorrosion, heat-insulation, sound-insulation, shock absorption and high&low temperature resistance. They are used for radomes, inlets, airfoils(fuel tank included), flap, aileron, vertical tail, horizontal tail, air brake, skin, baseboards and tails, etc. Its hardness is up to 62~65HRC. The holes are greatly affected by the fibre laminates direction of carbon fibre reinforced composite material due to its anisotropy when drilling in unidirectional laminates. There are burrs, splits at the exit because of stress concentration. Besides there is delamination and the hole is prone to be smaller. Burrs are caused by poor sharpness of cutting edge, delamination, tearing, splitting are caused by the great stress caused by high thrust force. Poorer sharpness of cutting edge leads to lower cutting performance and higher drilling force at the same time. The present research focuses on the interrelation between rotation speed, feed, drill's geometry, drill life, cutting mode, tools material etc. and thrust force. At the same time, holes quantity and holes making difficulty of composites have also increased. It requires high performance drills which won't bring out defects and have long tool life. It has become a trend to develop super hard material tools and tools with special geometry for drilling

  5. Teaching Advanced ESL Composition with an Internet Courseware

    Institute of Scientific and Technical Information of China (English)

    James J. Kohn


    In the Spring of 1999, this writer experimented in the use of a software program as an adjunct to an advanced-level English composition class for international students at San Francisco State University. In this paper, he presents a summary of the results of the experiment, including a description of the courseware program which was used, some samples of the activities, and an evaluation of the class based in part on the students' own assessment of the program.

  6. Fluid Structure Interaction Effect on Sandwich Composite Structures (United States)


    14. SUBJECT TERMS Fluid Structure Interaction, FSI, composite, balsa, low velocity impact, sandwich composites, VARTM , Vacuum Assisted Resin Transfer...11 1. Vacuum Assisted Resin Transfer Molding ( VARTM ) ...................11 2. Procedure...required equipment for VARTM composite production. ..............10 Figure 4. VARTM Lay-up (From [8

  7. Annual Conference on Composites and Advanced Ceramic Materials, 11th, Cocoa Beach, FL, Jan. 18-23, 1987, Proceedings

    Energy Technology Data Exchange (ETDEWEB)


    The present conference on advanced ceramic materials discusses topics in the fields of NDE, coating/joining/tribology techniques, fracture and interface phenomena, whisker- and particulate-reinforced composites, fiber and whisker properties, SiC and Si/sub 3/N/sub 4/, glass/glass-ceramic matrix composites, alumina-matrix composites, ceramic materials for space structures, and SiC- and Si/sub 3/N/sub 4/-matrix composites. Attention is given to ceramic characterization by thermal wave imaging, an advanced ceramic-to-metal joining process, the fracture modes of brittle-matrix unidirectional composites, the oxidation of SiC-containing composites, particulate matter in SiC whiskers, corrosion reactions in SiC ceramics, melt-infiltrated ceramic-matrix composites, environmental effects in toughened ceramics, and a ceramic composite heat exchanger.

  8. Optimum lay-up design of variable stiffness composite structures



    Advancements in automated fibre-placement (AFP) technology make it possible to take laminate tailoring further than just stacking sequence optimisation; they enable the designer to vary the fibre orientation angle spatially within each ply. Spatial variation of fibre orientation angles results in a variable stiffness (VS) laminate. The work presented in this thesis constitutes a possible second step of a two-step design process for VS composite structures. The first step is to optimise a VS c...

  9. Intelligent composites and structures -- a review

    Energy Technology Data Exchange (ETDEWEB)

    Jang, B.Z. [Auburn Univ., AL (United States)


    Functionally responsive composites, as precursors to intelligent or smart material systems, are reviewed. These include composites containing a complex network of sensors that can monitor several parameters simultaneously over the entire lifetime of the structure. For instance, fiber optic sensors can be used for (1) monitoring the manufacturing process, (2) augmenting nondestructive evaluation technique, (3) enabling structure health monitoring and damage assessment systems, and (4) supporting control system. Significant progress has been made towards controlling structural radiated noise by active/adaptive means applied directly to the structure. By incorporating electrorheological (ER) fluids in composites, one can produce a new class of materials of which the mechanical properties can be changed in situ. By adjusting the rheological properties of the ER fluid through an electric field, both stiffness and damping capabilities can be altered. Active vibration control can also be achieved by incorporating a shape memory alloy (SMA, e.g. Nitinol) in a fiber reinforced composite as the embedded distributed actuators. The SMA embedded laminates have the capabilities to change their material properties, modify the stress and strain state of the structure, and possibly alter its configuration possibly in a controlled manner. The advantages and limitations of ER fluids, piezoelectric ceramics, and SMAs as the actuators for smart structures will be discussed. Also to be discussed are the theoretical basis, some fabrication techniques, and potential applications of piezoelectric composites and optical composites.

  10. On the structural analysis of textile composites (United States)

    Bogdanovich, Alexander E.; Pastore, Christopher M.

    The local structural inhomogeneities which distinguish textile composites from laminated materials are discussed. Techniques for quantifying these inhomogeneities through three dimensional geometric modelling are introduced and methods of translating them into elastic properties are presented. Some basic ideas on application of spline functions to the stress field analysis in textile composites are proposed. The significance of internal continuity conditions for these materials is emphasized. Several analytical techniques based on the concept of a meso-volume are discussed. An example is presented to demonstrate the application of the method to structural analysis of textile composites.

  11. Voids' System in the Woven Composite Structure

    Institute of Scientific and Technical Information of China (English)

    Pavla VOZKOVA


    Composites are common material constructions for high-tech use now. Mechanical properties of woven reinforced composites are influenced by voids inside the structure.Voids could be classified to the two sections. Long and thin cracks are more dangerous than pores. It is important to find relations between preparation and place of occurrence of voids. This paper classifies defects according to rise mechanism, point of occurrence, orientation, size and affect to the properties. Image analysis was used for observing samples. Future work would be oriented not only to observing real samples, but also to calculate mechanical properties from real and ideal structures in 3D woven reinforced composites.

  12. Integrated Design for Manufacturing of Braided Preforms for Advanced Composites Part I: 2D Braiding (United States)

    Gao, Yan Tao; Ko, Frank K.; Hu, Hong


    This paper presents a 2D braiding design system for advanced textile structural composites was based on dynamic models. A software package to assist in the design of braided preform manufacturing has been developed. The package allows design parameters (machine speeds, fiber volume fraction, tightness factor, etc.) to be easily obtained and the relationships between said parameters to be demonstrated graphically. The fabirc geometry model (FGM) method was adopted to evaluate the mechanical properties of the composites. Experimental evidence demonstrates the success of the use of dynamic models in the design software for the manufacture of braided fabric preforms.

  13. The homes of tomorrow: service composition and advanced user interfaces

    Directory of Open Access Journals (Sweden)

    Claudio Di Ciccio


    Full Text Available Home automation represents a growing market in the industrialized world. Today’s systems are mainly based on ad hoc and proprietary solutions, with little to no interoperability and smart integration. However, in a not so distant future, our homes will be equipped with many sensors, actuators and devices, which will collectively expose services, able to smartly interact and integrate, in order to offer complex services providing even richer functionalities. In this paper we present the approach and results of SM4ALL- Smart hoMes for All, a project investigating automatic service composition and advanced user interfaces applied to domotics.

  14. Ultrasonic and radiographic evaluation of advanced aerospace materials: Ceramic composites (United States)

    Generazio, Edward R.


    Two conventional nondestructive evaluation techniques were used to evaluate advanced ceramic composite materials. It was shown that neither ultrasonic C-scan nor radiographic imaging can individually provide sufficient data for an accurate nondestructive evaluation. Both ultrasonic C-scan and conventional radiographic imaging are required for preliminary evaluation of these complex systems. The material variations that were identified by these two techniques are porosity, delaminations, bond quality between laminae, fiber alignment, fiber registration, fiber parallelism, and processing density flaws. The degree of bonding between fiber and matrix cannot be determined by either of these methods. An alternative ultrasonic technique, angular power spectrum scanning (APSS) is recommended for quantification of this interfacial bond.

  15. Composites on the way to structural automotive applications

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, H.; Kopp, J.; Stieg, J. [Volkswagen AG, Wolfsburg (Germany)


    Against the background of a steady increase of the standards on comfort, passive safety and driving performance of vehicles as well as the commitment to reduce fuel consumption and carbon dioxide emissions, the demand for lightweight construction attains paramount importance. The use of aluminum, magnesium or new steel alloys in the body structure can lead to significant weight reduction compared with conventional steel concepts. Furthermore, maximum weight reduction will require an intensive use of advanced composites in primary structures. The paper deals with the potentials and the challenges coming along with the introduction of advanced composites into automotive series production. Presently, liquid composite molding and compression molding of high-performance SMC are the most promising technologies to achieve demanding composite parts with high fiber volume fraction, good surface quality and controlled mechanical properties. The performance of specific automotive application processed in these techniques is presented and discussed. On principle, the cost/benefit aspect is of decisive importance for larger volume applications. Considerable efforts are necessary to reduce material and semi-finished product costs and to provide manufacturing technologies which are capable of allowing large-volume automotive production of composite components. Especially concepts are desirable which do not only provide a basic material substitution but rather an intelligent design based on component and functional integration as one of the most effective strategies to exploit the advantages of advanced composites. These aspects will be regarded and a brief summary on some other remaining challenges like recycling, crash simulation or joining and assembly technologies for mixed material concepts will be given. (orig.)

  16. Multiscale carbon nanotube-carbon fiber reinforcement for advanced epoxy composites. (United States)

    Bekyarova, E; Thostenson, E T; Yu, A; Kim, H; Gao, J; Tang, J; Hahn, H T; Chou, T-W; Itkis, M E; Haddon, R C


    We report an approach to the development of advanced structural composites based on engineered multiscale carbon nanotube-carbon fiber reinforcement. Electrophoresis was utilized for the selective deposition of multi- and single-walled carbon nanotubes (CNTs) on woven carbon fabric. The CNT-coated carbon fabric panels were subsequently infiltrated with epoxy resin using vacuum-assisted resin transfer molding (VARTM) to fabricate multiscale hybrid composites in which the nanotubes were completely integrated into the fiber bundles and reinforced the matrix-rich regions. The carbon nanotube/carbon fabric/epoxy composites showed approximately 30% enhancement of the interlaminar shear strength as compared to that of carbon fiber/epoxy composites without carbon nanotubes and demonstrate significantly improved out-of-plane electrical conductivity.

  17. Lithographically defined microporous carbon-composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Burckel, David Bruce; Washburn, Cody M.; Lambert, Timothy N.; Finnegan, Patrick Sean; Wheeler, David R.


    A microporous carbon scaffold is produced by lithographically patterning a carbon-containing photoresist, followed by pyrolysis of the developed resist structure. Prior to exposure, the photoresist is loaded with a nanoparticulate material. After pyrolysis, the nanonparticulate material is dispersed in, and intimately mixed with, the carbonaceous material of the scaffold, thereby yielding a carbon composite structure.

  18. Production defects in marine composite structures

    DEFF Research Database (Denmark)

    Hayman, Brian; Berggreen, Christian; Tsouvalis, Nicholas G.


    Composite structures are often used when there is a requirement for low weight. Then a key aspect is to be able to take full advantage of the material and utilise it to its limits. To do this it is important to achieve as low a variability as possible in the manufacture of such structures...

  19. Fabrication and Structure Characterization of Alumina-Aluminum Interpenetrating Phase Composites (United States)

    Dolata, Anna J.


    Alumina-Aluminum composites with interpenetrating networks structure belong to advanced materials with potentially better properties when compared with composites reinforced by particles or fibers. The paper presents the experimental results of fabrication and structure characterization of Al matrix composites locally reinforced via Al2O3 ceramic foam. The composites were obtained using centrifugal infiltration of porous ceramics by liquid aluminum alloy. Both scanning electron microscopy (SEM + EDS) and x-ray tomography were used to determine the structure of foams and composites especially in reinforced areas. The quality of castings, degree of pore filling in ceramic foams by Al alloy, and microstructure in area of interface were assessed.

  20. Advanced computational aeroelasticity and multidisciplinary application for composite curved wing


    Kim, Dong-Hyun; Kim, Yu-Sung


    This article preferentially describes advanced computational aeroelasticity and its multidisciplinary applications based on the coupled CFD (Computational Fluid Dynamics) and CSD (Computational Structural Dynamics) method. A modal-based coupled nonlinear aeroelastic analysis system incorporated with unsteady Euler aerodynamics has been developed based on the high-speed parallel processing technique. It is clearly expected to give accurate and practical engineering data in the design fields of...

  1. The Compositional Structure of the Asteroid Belt

    CERN Document Server

    DeMeo, Francesca E; Walsh, Kevin J; Chapman, Clark R; Binzel, Richard P


    The past decade has brought major improvements in large-scale asteroid discovery and characterization with over half a million known asteroids and over 100,000 with some measurement of physical characterization. This explosion of data has allowed us to create a new global picture of the Main Asteroid Belt. Put in context with meteorite measurements and dynamical models, a new and more complete picture of Solar System evolution has emerged. The question has changed from "What was the original compositional gradient of the Asteroid Belt?" to "What was the original compositional gradient of small bodies across the entire Solar System?" No longer is the leading theory that two belts of planetesimals are primordial, but instead those belts were formed and sculpted through evolutionary processes after Solar System formation. This article reviews the advancements on the fronts of asteroid compositional characterization, meteorite measurements, and dynamical theories in the context of the heliocentric distribution of...

  2. Shock Wave Structure in Particulate Composites (United States)

    Rauls, Michael; Ravichandran, Guruswami


    Shock wave experiments are conducted on a particulate composite consisting of a polymethyl methacrylate (PMMA) matrix reinforced by glass beads. Such a composite with an impedance mismatch of 4.3 closely mimics heterogeneous solids of interest such as concrete and energetic materials. The composite samples are prepared using a compression molding process. The structure and particle velocity rise times of the shocks are examined using forward ballistic experiments. Reverse ballistic experiments are used to track how the interface density influences velocity overshoot above the steady state particle velocity. The effects of particle size (0.1 to 1 mm) and volume fraction of glass beads (30-40%) on the structure of the leading shock wave are investigated. It is observed that the rise time increases with increasing particle size and scales linearly for the range of particle sizes considered here. Results from numerical simulations using CTH are compared with experimental results to gain insights into wave propagation in heterogeneous particulate composites.

  3. Composite electrode/electrolyte structure (United States)

    Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.


    Provided is an electrode fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. Onto this electrode in the green state, a green ionic (e.g., electrolyte) film is deposited and the assembly is co-fired at a temperature suitable to fully densify the film while the substrate retains porosity. Subsequently, a catalytic material is added to the electrode structure by infiltration of a metal salt and subsequent low temperature firing. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems.

  4. Design of a robust SHM system for composite structures (United States)

    Beard, Shawn; Liu, Ching-Chao; Chang, Fu-Kuo


    Composites are becoming increasingly popular materials used in a wide range of applications on large-scale structures such as windmill blades, rocket motor cases, and aircraft fuselage and wings. For these large structures, using composites greatly enhances the operation and performance of the application, but also introduces extraordinary inspection challenges that push the limits of traditional NDE in terms of time and cost. Recent advances in Structural Health Monitoring (SHM) technologies offer a promising solution to these inspection challenges. But efficient design methodologies and implementation procedures are needed to ensure the reliability and robustness of SHM technologies for use in real-world applications. This paper introduces the essential elements of the design and implementation process by way of example. State-of-the-art techniques to optimize sensor placement, perform self-diagnostics, compensate for environmental conditions, and generate probability of detection (POD) curves for any application are discussed. The techniques are presented in relation to Acellent's recently developed SmartComposite System that is used to monitor the integrity of large composite structures. The system builds on the active sensor network technology of Acellent that is analogous to a built-in acousto-ultrasonic NDE system. Key features of the system include new miniaturized lightweight hardware, self-diagnostics and adaptive algorithm to automatically compensate for damaged sensors, reliable damage detection under different environmental conditions, and generation of POD curves. This paper will provide an overview of the system and demonstrate its key features.

  5. High-strain composites and dual-matrix composite structures (United States)

    Maqueda Jimenez, Ignacio

    Most space applications require deployable structures due to the limiting size of current launch vehicles. Specifically, payloads in nanosatellites such as CubeSats require very high compaction ratios due to the very limited space available in this typo of platform. Strain-energy-storing deployable structures can be suitable for these applications, but the curvature to which these structures can be folded is limited to the elastic range. Thanks to fiber microbuckling, high-strain composite materials can be folded into much higher curvatures without showing significant damage, which makes them suitable for very high compaction deployable structure applications. However, in applications that require carrying loads in compression, fiber microbuckling also dominates the strength of the material. A good understanding of the strength in compression of high-strain composites is then needed to determine how suitable they are for this type of application. The goal of this thesis is to investigate, experimentally and numerically, the microbuckling in compression of high-strain composites. Particularly, the behavior in compression of unidirectional carbon fiber reinforced silicone rods (CFRS) is studied. Experimental testing of the compression failure of CFRS rods showed a higher strength in compression than the strength estimated by analytical models, which is unusual in standard polymer composites. This effect, first discovered in the present research, was attributed to the variation in random carbon fiber angles respect to the nominal direction. This is an important effect, as it implies that microbuckling strength might be increased by controlling the fiber angles. With a higher microbuckling strength, high-strain materials could carry loads in compression without reaching microbuckling and therefore be suitable for several space applications. A finite element model was developed to predict the homogenized stiffness of the CFRS, and the homogenization results were used in

  6. Advanced Measurements of Silicon Carbide Ceramic Matrix Composites

    Energy Technology Data Exchange (ETDEWEB)

    Farhad Farzbod; Stephen J. Reese; Zilong Hua; Marat Khafizov; David H. Hurley


    Silicon carbide (SiC) is being considered as a fuel cladding material for accident tolerant fuel under the Light Water Reactor Sustainability (LWRS) Program sponsored by the Nuclear Energy Division of the Department of Energy. Silicon carbide has many potential advantages over traditional zirconium based cladding systems. These include high melting point, low susceptibility to corrosion, and low degradation of mechanical properties under neutron irradiation. In addition, ceramic matrix composites (CMCs) made from SiC have high mechanical toughness enabling these materials to withstand thermal and mechanical shock loading. However, many of the fundamental mechanical and thermal properties of SiC CMCs depend strongly on the fabrication process. As a result, extrapolating current materials science databases for these materials to nuclear applications is not possible. The “Advanced Measurements” work package under the LWRS fuels pathway is tasked with the development of measurement techniques that can characterize fundamental thermal and mechanical properties of SiC CMCs. An emphasis is being placed on development of characterization tools that can used for examination of fresh as well as irradiated samples. The work discuss in this report can be divided into two broad categories. The first involves the development of laser ultrasonic techniques to measure the elastic and yield properties and the second involves the development of laser-based techniques to measurement thermal transport properties. Emphasis has been placed on understanding the anisotropic and heterogeneous nature of SiC CMCs in regards to thermal and mechanical properties. The material properties characterized within this work package will be used as validation of advanced materials physics models of SiC CMCs developed under the LWRS fuels pathway. In addition, it is envisioned that similar measurement techniques can be used to provide process control and quality assurance as well as measurement of

  7. Life of structures of composite materials

    Energy Technology Data Exchange (ETDEWEB)

    Koznetsov, N.D.; Stepanenko, N.D.


    The introduction of composite materials in gas turbine engines is rationally done in stages. It is desirable to concentrate efforts on the use of them for production of vanes, sound deadening panes, the reverse rod, and other elements of the stator. The authors use compressor blades as an example of the basic principles of design, the selection of the reinforcing structure, and inspection of the quality of structures of composite materials. A method of determination of the elastodamping properties of polymer composite materials on specimens with free ends in high frequency flexural vibrations excited by a modulated jet of compressed air has been developed and standardized. With the use of this method such defects as separations, cracks, disorientation of the reinforcing, deviations in the order of alternation and the angular orientation of the layers are revealed.

  8. Bonded repair of composite aircraft structures: A review of scientific challenges and opportunities (United States)

    Katnam, K. B.; Da Silva, L. F. M.; Young, T. M.


    Advanced composite materials have gained popularity in high-performance structural designs such as aerospace applications that require lightweight components with superior mechanical properties in order to perform in demanding service conditions as well as provide energy efficiency. However, one of the major challenges that the aerospace industry faces with advanced composites - because of their inherent complex damage behaviour - is structural repair. Composite materials are primarily damaged by mechanical loads and/or environmental conditions. If material damage is not extensive, structural repair is the only feasible solution as replacing the entire component is not cost-effective in many cases. Bonded composite repairs (e.g. scarf patches) are generally preferred as they provide enhanced stress transfer mechanisms, joint efficiencies and aerodynamic performance. With an increased usage of advanced composites in primary and secondary aerospace structural components, it is thus essential to have robust, reliable and repeatable structural bonded repair procedures to restore damaged composite components. But structural bonded repairs, especially with primary structures, pose several scientific challenges with the current existing repair technologies. In this regard, the area of structural bonded repair of composites is broadly reviewed - starting from damage assessment to automation - to identify current scientific challenges and future opportunities.

  9. Structure-performance maps of polymeric, metal, and ceramic matrix composites (United States)

    Chou, Tsu-Wei; Yang, Jenn-Ming


    This paper presents the results of extensive analytical studies of the thermo-elastic properties of unidirectional laminated composites, as well as two-dimensional and three-dimensional textile structural composites with polymeric, metal, and ceramic matrices. Some comparisons of the theoretical predictions with experimental data have been made. By the construction of the structure-performance maps, the effective composite properties based upon various reinforcement forms and fiber and matrix combinations can be easily assessed. The uniqueness of various textile structural reinforcements also has been demonstrated. These comprehensive performance maps can provide the data base necessary for material selections and guidance for future investigations of advanced composites.

  10. The use of advanced materials in space structure applications (United States)

    Eaton, D. C. G.; Slachmuylders, E. J.

    The last decade has seen the Space applications of composite materials become almost commonplace in the construction of configurations requiring high stiffness and/or dimensional stability, particularly in the field of antennas. As experience has been accumulated, applications for load carrying structures utilizing the inherent high specific strength/stiffness of carbon fibres have become more frequent. Some typical examples of these and their design development criteria are reviewed. As these structures and the use of new plastic matrices emerge, considerable attention has to be given to establishing essential integrity control requirements from both safety and cost aspects. The advent of manned European space flight places greater emphasis on such requirements. Attention is given to developments in the fields of metallic structures with discussion of the advantages and disadvantages of their application. The design and development of hot structures, thermal protection systems and air-breathing engines for future launch vehicles necessitates the use of the emerging metal/matrix and other advanced materials. Some of their important features are outlined. Means of achieving such objectives by greater harmonization within Europe are emphasized. Typical examples of on-going activities to promote such collaboration are described.

  11. Advanced carbon materials/olivine LiFePO4 composites cathode for lithium ion batteries (United States)

    Gong, Chunli; Xue, Zhigang; Wen, Sheng; Ye, Yunsheng; Xie, Xiaolin


    In the past two decades, LiFePO4 has undoubtly become a competitive candidate for the cathode material of the next-generation LIBs due to its abundant resources, low toxicity and excellent thermal stability, etc. However, the poor electronic conductivity as well as low lithium ion diffusion rate are the two major drawbacks for the commercial applications of LiFePO4 especially in the power energy field. The introduction of highly graphitized advanced carbon materials, which also possess high electronic conductivity, superior specific surface area and excellent structural stability, into LiFePO4 offers a better way to resolve the issue of limited rate performance caused by the two obstacles when compared with traditional carbon materials. In this review, we focus on advanced carbon materials such as one-dimensional (1D) carbon (carbon nanotubes and carbon fibers), two-dimensional (2D) carbon (graphene, graphene oxide and reduced graphene oxide) and three-dimensional (3D) carbon (carbon nanotubes array and 3D graphene skeleton), modified LiFePO4 for high power lithium ion batteries. The preparation strategies, structure, and electrochemical performance of advanced carbon/LiFePO4 composite are summarized and discussed in detail. The problems encountered in its application and the future development of this composite are also discussed.

  12. A Nonlinear Theory for Smart Composite Structures (United States)

    Chattopadhyay, Aditi


    The paper discusses the following: (1) Development of a completely coupled thermo-piezoelectric-mechanical theory for the analysis of composite shells with segmented and distributed piezoelectric sensor/actuators and shape memory alloys. The higher order displacement theory will be used to capture the transverse shear effects in anisotropic composites. The original theory will be modified to satisfy the stress continuity at ply interfaces. (2) Development of a finite element technique to implement the mathematical model. (3) Investigation of the coupled structures/controls interaction problem to study the complex trade-offs associated with the coupled problem.

  13. Dynamic Failure of Composite and Sandwich Structures

    CERN Document Server

    Abrate, Serge; Rajapakse, Yapa D S


    This book presents a broad view of the current state of the art regarding the dynamic response of composite and sandwich structures subjected to impacts and explosions. Each chapter combines a thorough assessment of the literature with original contributions made by the authors.  The first section deals with fluid-structure interactions in marine structures.  The first chapter focuses on hull slamming and particularly cases in which the deformation of the structure affects the motion of the fluid during the water entry of flexible hulls. Chapter 2 presents an extensive series of tests underwater and in the air to determine the effects of explosions on composite and sandwich structures.  Full-scale structures were subjected to significant explosive charges, and such results are extremely rare in the open literature.  Chapter 3 describes a simple geometrical theory of diffraction for describing the interaction of an underwater blast wave with submerged structures. The second section addresses the problem of...

  14. Structural dynamic analysis of composite beams (United States)

    Suresh, J. K.; Venkatesan, C.; Ramamurti, V.


    In the treatment of the structural dynamic problem of composite materials, two alternate types of formulations, based on the elastic modulus and compliance quantities, exist in the literature. The definitions of the various rigidities are observed to differ in these two approaches. Following these two types of formulation, the structural dynamic characteristics of a composite beam are analyzed. The results of the analysis are compared with those available in the literature. Based on the comparison, the influence of the warping function in defining the coupling terms in the modulus approach and also on the natural frequencies of the beam has been identified. It is found from the analysis that, in certain cases, the difference between the results of the two approaches is appreciable. These differences may be attributed to the constraints imposed on the deformation and flexibility of the beam by the choice of the description of the warping behaviour. Finally, the influence of material properties on the structural dynamic characteristics of the beam is studied for different composites for various angles of orthotropy.

  15. Conceptual design study of advanced acoustic composite nacelle. [for achieving reductions in community noise and operating expense (United States)

    Goodall, R. G.; Painter, G. W.


    Conceptual nacelle designs for wide-bodied and for advanced-technology transports were studied with the objective of achieving significant reductions in community noise with minimum penalties in airplane weight, cost, and in operating expense by the application of advanced composite materials to nacelle structure and sound suppression elements. Nacelle concepts using advanced liners, annular splitters, radial splitters, translating centerbody inlets, and mixed-flow nozzles were evaluated and a preferred concept selected. A preliminary design study of the selected concept, a mixed flow nacelle with extended inlet and no splitters, was conducted and the effects on noise, direct operating cost, and return on investment determined.

  16. Advanced Ceramic Matrix Composites (CMCs) for High Temperature Applications (United States)

    Singh, M.


    Advanced ceramic matrix composites (CMCs) are enabling materials for a number of demanding applications in aerospace, energy, and nuclear industries. In the aerospace systems, these materials are being considered for applications in hot sections of jet engines such as the combustor liner, vanes, nozzle components, nose cones, leading edges of reentry vehicles, and space propulsion components. Applications in the energy and environmental industries include radiant heater tubes, heat exchangers, heat recuperators, gas and diesel particulate filters, and components for land based turbines for power generation. These materials are also being considered for use in the first wall and blanket components of fusion reactors. In the last few years, a number of CMC components have been developed and successfully tested for various aerospace and ground based applications. However, a number of challenges still remain slowing the wide scale implementation of these materials. They include robust fabrication and manufacturing, assembly and integration, coatings, property modeling and life prediction, design codes and databases, repair and refurbishment, and cost. Fabrication of net and complex shape components with high density and tailorable matrix properties is quite expensive, and even then various desirable properties are not achievable. In this presentation, a number of examples of successful CMC component development and testing will be provided. In addition, critical need for robust manufacturing, joining and assembly technologies in successful implementation of these systems will be discussed.

  17. Imperfection Insensitivity Analyses of Advanced Composite Tow-Steered Shells (United States)

    Wu, K. Chauncey; Farrokh, Babak; Stanford, Bret K.; Weaver, Paul M.


    Two advanced composite tow-steered shells, one with tow overlaps and another without overlaps, were previously designed, fabricated and tested in end compression, both without cutouts, and with small and large cutouts. In each case, good agreement was observed between experimental buckling loads and supporting linear bifurcation buckling analyses. However, previous buckling tests and analyses have shown historically poor correlation, perhaps due to the presence of geometric imperfections that serve as failure initiators. For the tow-steered shells, their circumferential variation in axial stiffness may have suppressed this sensitivity to imperfections, leading to the agreement noted between tests and analyses. To investigate this further, a numerical investigation was performed in this study using geometric imperfections measured from both shells. Finite element models of both shells were analyzed first without, and then, with measured imperfections that were then, superposed in different orientations around the shell longitudinal axis. Small variations in both the axial prebuckling stiffness and global buckling load were observed for the range of imperfections studied here, which suggests that the tow steering, and resulting circumferentially varying axial stiffness, may result in the test-analysis correlation observed for these shells.

  18. Advances in Ceramic Matrix Composite Blade Damping Characteristics for Aerospace Turbomachinery Applications (United States)

    Min, James B.; Harris, Donald L.; Ting, J. M.


    For advanced aerospace propulsion systems, development of ceramic matrix composite integrally-bladed turbine disk technology is attractive for a number of reasons. The high strength-to-weight ratio of ceramic composites helps to reduce engine weight and the one-piece construction of a blisk will result in fewer parts count, which should translate into reduced operational costs. One shortcoming with blisk construction, however, is that blisks may be prone to high cycle fatigue due to their structural response to high vibration environments. Use of ceramic composites is expected to provide some internal damping to reduce the vibratory stresses encountered due to unsteady flow loads through the bladed turbine regions. A goal of our research was to characterize the vibration viscous damping behavior of C/SiC composites. The vibration damping properties were measured and calculated. Damping appeared to decrease with an increase in the natural frequency. While the critical damping amount of approximately 2% is required for typical aerospace turbomachinery engines, the C/SiC damping at high frequencies was less than 0.2% from our study. The advanced high-performance aerospace propulsion systems almost certainly will require even more damping than what current vehicles require. A purpose of this paper is to review some work on C/SiC vibration damping by the authors for the NASA CMC turbine blisk development program and address an importance of the further investigation of the blade vibration damping characteristics on candidate CMC materials for the NASA s advanced aerospace turbomachinery engine systems.

  19. Development of a metal-clad advanced composite shear web design concept (United States)

    Laakso, J. H.


    An advanced composite web concept was developed for potential application to the Space Shuttle Orbiter main engine thrust structure. The program consisted of design synthesis, analysis, detail design, element testing, and large scale component testing. A concept was sought that offered significant weight saving by the use of Boron/Epoxy (B/E) reinforced titanium plate structure. The desired concept was one that was practical and that utilized metal to efficiently improve structural reliability. The resulting development of a unique titanium-clad B/E shear web design concept is described. Three large scale components were fabricated and tested to demonstrate the performance of the concept: a titanium-clad plus or minus 45 deg B/E web laminate stiffened with vertical B/E reinforced aluminum stiffeners.

  20. Predicting Career Advancement with Structural Equation Modelling (United States)

    Heimler, Ronald; Rosenberg, Stuart; Morote, Elsa-Sofia


    Purpose: The purpose of this paper is to use the authors' prior findings concerning basic employability skills in order to determine which skills best predict career advancement potential. Design/methodology/approach: Utilizing survey responses of human resource managers, the employability skills showing the largest relationships to career…

  1. Interfacial chemistry and structure in ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Jones, R.H.; Saenz, N.T.; Schilling, C.H.


    The interfacial chemistry and structure of ceramic matrix composites (CMCs) play a major role in the properties of these materials. Fiber-matrix interfaces chemistries are vitally important in the fracture strength, fracture toughness, and fracture resistance of ceramic composites because they influence fiber loading and fiber pullout. Elevated-temperature properties are also linked to the interfacial characteristics through the chemical stability of the interface in corrosive environments and the creep/pullout behavior of the interface. Physical properties such as electrical and thermal conductivity are also dependent on the interface. Fiber-matrix interfaces containing a 1-{mu}m-thick multilayered interface with amorphous and graphitic C to a 1-nm-thick SiO{sub 2} layer can result from sintering operations for some composite systems. Fibers coated with C, BN, C/BC/BN, and Si are also used to produce controlled interface chemistries and structures. Growth interfaces within the matrix resulting from processing of CMCs can also be crucial to the behavior of these materials. Evaluation of the interfacial chemistry and structure of CMCs requires the use of a variety of analytical tools, including optical microscopy, scanning electron microscopy, Auger electron spectroscopy, and transmission electron microscopy coupled with energy dispersive x-ray analysis. A review of the interfacial chemistry and structure of SiC whisker- and fiber-reinforced Si{sub 3}N{sub 4} and SiC/SiC materials is presented. Where possible, correlations with fracture properties and high-temperature stability are made. 94 refs., 10 figs.

  2. Thermography Inspection for Early Detection of Composite Damage in Structures During Fatigue Loading (United States)

    Zalameda, Joseph N.; Burke, Eric R.; Parker, F. Raymond; Seebo, Jeffrey P.; Wright, Christopher W.; Bly, James B.


    Advanced composite structures are commonly tested under controlled loading. Understanding the initiation and progression of composite damage under load is critical for validating design concepts and structural analysis tools. Thermal nondestructive evaluation (NDE) is used to detect and characterize damage in composite structures during fatigue loading. A difference image processing algorithm is demonstrated to enhance damage detection and characterization by removing thermal variations not associated with defects. In addition, a one-dimensional multilayered thermal model is used to characterize damage. Lastly, the thermography results are compared to other inspections such as non-immersion ultrasonic inspections and computed tomography X-ray.

  3. Monitoring of Structural Integrity of Composite Structures by Embedded Optical Fiber Sensors (United States)

    Osei, Albert J.


    advanced structural materials expected to become the mainstay of the current and future generation space structures. Since carbon-epoxy composites are the materials of choice for the current space structures, the initial study is concentrated on this type of composite. The goals of this activity are to use embedded FBG sensors for measuring strain and temperature of composite structures, and to investigate the effects of various parameters such as composite fiber orientation with respect to the optical sensor, unidirectional fiber composite, fabrication process etc., on the optical performance of the sensor. This paper describes an experiment to demonstrate the use of an embedded FBG for measuring strain in a composite material. The performance of the fiber optic sensor is determined by direct comparison with results from more conventional instrumentation.

  4. Manufacturing and NDE of Large Composite Aerospace Structures at MSFC (United States)

    Whitaker, Ann


    NASA's vision for transportation to orbit calls for new vehicles built with new materials technology. The goals of this new launch system development are to improve safety, dramatically reduce cost to orbit, and improve vehicle turn around time. Planned Space Shuttle upgrades include new reusable liquid propellant boosters to replace the solid propellant boosters. These boosters are to have wings and return to the launch site for a horizontal landing on an airport runway. New single and two stages to orbit concepts are being investigated. To reduce weight and improve performance composite materials are proposed for fuel and oxidizer tanks, fuel feedlines, valve bodies, aerostructures, turbomachinery components. For large composite structures new methods of fabrication are being proposed and developed. Containment of cryogenic fuel or oxidizer requires emphases on composite material densification and chemical compatibility. Ceramic matrix and fiber composites for hot rotating turbomachinery have been developed with new fabrication processes. The new requirements on the materials for launcher components are requiring development of new manufacturing and inspection methods. This talk will examine new and proposed manufacturing methods to fabricate the revolutionary components. New NDE methods under consideration include alternative X-ray methods, X-ray laminagraphy, advanced CT, Thermography, new ultrasonic methods, and imbedded sensors. The sizes, complexity, use environment, and contamination restrictions will challenge the inspection process. In flight self-diagnosis and rapid depot inspection are also goals of the NDE development.

  5. Structural Health Monitoring of Composite Structures Using Fiber Optic Sensors (United States)

    Whitaker, Anthony

    Structural health monitoring is the process of detecting damage to a structure, where damage can be characterized as changes to material/mechanical properties including but not limited to plastically deforming the material or the modification of connections. Fiber optic cables with fiber Bragg gratings have emerged as a reliable method of locally measuring strains within a structure. During the manufacturing of composite structures, the fiber optic cables can be embedded between lamina plies, allowing the ability to measure strain at discrete locations within the structure as opposed to electrical strain gauges, which must typically be applied to the surface only. The fiber optic sensors may be used to see if the local strain at the sensor location is beyond desired limits, or the array response may be mined to determine additional information about the loading applied to the structure. The work presented in this thesis is to present novel and potential applications of FBG sensors being used to assess the health of the structure. The first application is the dual application of the FBG sensor as a method to determine the strain around a bolt connection as well as the preload of the fastener using a single fiber optic sensor. The composite material around the bolted connections experience stress concentrations and are often the location of damage to the structure from operational cyclic loading over the lifetime of the structure. The degradation can occur more quickly if the fastener is insufficiently tight to transfer load properly. The second application is the ability to locate the impact location of a projectile with damaging and non-damaging energy. By locating and quantifying the damage, the sensor array provides the basis for a structural health monitoring system that has the potential to determine if the damage is extensive enough to replace, or if the part can be salvaged and retrofitted.

  6. Biomimetic Composite Structural T-joints

    Institute of Scientific and Technical Information of China (English)

    Vimal Kumar Thummalapalli; Steven L.Donaldson


    Biological structural fixed joints exhibit unique attributes,including highly optimized fiber paths which minimize stress concentrations.In addition,since the joints consist of continuous,uncut fiber architectures,the joints enable the organism to transport information and chemicals from one part of the body to the other.To the contrary,sections of man-made composite material structures are often joined using bolted or bonded joints,which involve low strength and high stress concentrations.These methods are also expensive to achieve.Additional functions such as fluid transport,electrical signal delivery,and thermal conductivity across the joints typically require parasitic tubes,wires,and attachment clips.By using the biomimetic methods,we seek to overcome the limitations which are present in the conventional methods. In the present work,biomimetic co-cured composite sandwich T-joints were constructed using unidirectional glass fiber,epoxy resin,and structural foam.The joints were fabricated using the wet lay-up vacuum bag resin infusion method.Foam sandwich T-joints with multiple continuous fiber architectures and sandwich foam thickness were prepared.The designs were tested in quasi-static bending using a mechanical load frame.The significantweight savings using the biomimetic approaches is discussed,as well as a comparison of failure modes versus architecture is described.

  7. Advanced Data Structure and Geographic Information Systems (United States)

    Peuquet, D. (Principal Investigator)


    The current state of the art in specified areas of Geographic Information Systems GIS technology is examined. Study of the question of very large, efficient, heterogeneous spatial databases is required in order to explore the potential application of remotely sensed data for studying the long term habitability of the Earth. Research includes a review of spatial data structures and storage, development of operations required by GIS, and preparation of a testbed system to compare Vaster data structure with NASA's Topological Raster Structure.

  8. Potential for Advanced Thermoplastic Composites in Space Systems (United States)


    in gages down to 125 fxm. (34). 43 Damping The intrinsic damping of polymer matrix composite is one of three decades greater than aluminum or...PROPERTIES BETWEEN POLYMER MATRIX COMPOSITE , ALUMINUM, AND BERYLLIUM Polymer Matrix Composite Aluminum Beryllium Density, mg/m3 1.7 2.7 1.7...0*, 0*. 0*, 0"], laminate that is directionally stiffened for beam and tube applications. bMinimum polymer matrix composite gage is for six plies

  9. Advanced analysis for structural steel building design

    Institute of Scientific and Technical Information of China (English)

    Wai Fah CHEN


    The 2005 AISC LRFD Specifications for Structural Steel Buildings are making it possible for designers to recognize explicitly the structural resistance provided within the elastic and inelastic ranges of beha-vior and up to the maximum load limit state. There is an increasing awareness of the need for practical second-order analysis approaches for a direct determination of overall structural system response. This paper attempts to present a simple, concise and reasonably comprehens-ive introduction to some of the theoretical and practical approaches which have been used in the traditional and modern processes of design of steel building structures.

  10. Predicting RNA structure: advances and limitations. (United States)

    Hofacker, Ivo L; Lorenz, Ronny


    RNA secondary structures can be predicted using efficient algorithms. A widely used software package implementing a large number of computational methods is the ViennaRNA Package. This chapter describes how to use programs from the ViennaRNA Package to perform common tasks such as prediction of minimum free-energy structures, suboptimal structures, or base pairing probabilities, and generating secondary structure plots with reliability annotation. Moreover, we present recent methods to assess the folding kinetics of an RNA via 2D projections of the energy landscape, identification of local minima and energy barriers, or simulation of RNA folding as a Markov process.

  11. C-SiC Honeycomb for Advanced Flight Structures Project (United States)

    National Aeronautics and Space Administration — The proposed project is to manufacture a C-SiC honeycomb structure to use as a high temperature material in advanced aircraft, spacecraft and industrial...

  12. Aromatic/aliphatic diamine derivatives for advanced compositions and polymers (United States)

    Delozier, Donovan M. (Inventor); Watson, Kent A. (Inventor); Connell, John W. (Inventor); Smith, Jr., Joseph G. (Inventor)


    Novel compositions of matter comprise certain derivatives of 9,9-dialkyl fluorene diamine (AFDA). The resultant compositions, whether compositions of matter or monomers that are subsequently incorporated into a polymer, are unique and useful in a variety of applications. Useful applications of AFDA-based material include heavy ion radiation shielding components and components of optical and electronic devices.

  13. Center for Advanced Electrical and Structural Polymers (United States)


    Kapton. Films of TPI, PEI ( Ultem 6000), and blends of these materials having 50 and 80 percent by weight of TPI were produced. These films were yellowish...when blended with PEI. The second year’s effort resulted in the following conclusions: " Blends of Aurum 450X. -v ith Ultem 6000 are miscible over...the composition range studied (up to 50% Ultem ). 0 Crystallization is inhibited in the 80/20 TPI/PEI blend and virtually absent in the 50/50 blend. The

  14. Advanced finite element method in structural engineering

    CERN Document Server

    Long, Yu-Qiu; Long, Zhi-Fei


    This book systematically introduces the research work on the Finite Element Method completed over the past 25 years. Original theoretical achievements and their applications in the fields of structural engineering and computational mechanics are discussed.

  15. Damage Detection in Composite Structures with Wavenumber Array Data Processing (United States)

    Tian, Zhenhua; Leckey, Cara; Yu, Lingyu


    Guided ultrasonic waves (GUW) have the potential to be an efficient and cost-effective method for rapid damage detection and quantification of large structures. Attractive features include sensitivity to a variety of damage types and the capability of traveling relatively long distances. They have proven to be an efficient approach for crack detection and localization in isotropic materials. However, techniques must be pushed beyond isotropic materials in order to be valid for composite aircraft components. This paper presents our study on GUW propagation and interaction with delamination damage in composite structures using wavenumber array data processing, together with advanced wave propagation simulations. Parallel elastodynamic finite integration technique (EFIT) is used for the example simulations. Multi-dimensional Fourier transform is used to convert time-space wavefield data into frequency-wavenumber domain. Wave propagation in the wavenumber-frequency domain shows clear distinction among the guided wave modes that are present. This allows for extracting a guided wave mode through filtering and reconstruction techniques. Presence of delamination causes spectral change accordingly. Results from 3D CFRP guided wave simulations with delamination damage in flat-plate specimens are used for wave interaction with structural defect study.

  16. Structural Health Monitoring for Impact Damage in Composite Structures.

    Energy Technology Data Exchange (ETDEWEB)

    Roach, Dennis P.; Raymond Bond (Purdue); Doug Adams (Purdue)


    Composite structures are increasing in prevalence throughout the aerospace, wind, defense, and transportation industries, but the many advantages of these materials come with unique challenges, particularly in inspecting and repairing these structures. Because composites of- ten undergo sub-surface damage mechanisms which compromise the structure without a clear visual indication, inspection of these components is critical to safely deploying composite re- placements to traditionally metallic structures. Impact damage to composites presents one of the most signi fi cant challenges because the area which is vulnerable to impact damage is generally large and sometimes very dif fi cult to access. This work seeks to further evolve iden- ti fi cation technology by developing a system which can detect the impact load location and magnitude in real time, while giving an assessment of the con fi dence in that estimate. Fur- thermore, we identify ways by which impact damage could be more effectively identi fi ed by leveraging impact load identi fi cation information to better characterize damage. The impact load identi fi cation algorithm was applied to a commercial scale wind turbine blade, and results show the capability to detect impact magnitude and location using a single accelerometer, re- gardless of sensor location. A technique for better evaluating the uncertainty of the impact estimates was developed by quantifying how well the impact force estimate meets the assump- tions underlying the force estimation technique. This uncertainty quanti fi cation technique was found to reduce the 95% con fi dence interval by more than a factor of two for impact force estimates showing the least uncertainty, and widening the 95% con fi dence interval by a fac- tor of two for the most uncertain force estimates, avoiding the possibility of understating the uncertainty associated with these estimates. Linear vibration based damage detection tech- niques were investigated in the

  17. Advances in Composite Reflectors: From X-Ray to Radio Wave Astronomy (United States)

    Connell, S. J.; Abusafieh, A. A.; Mehle, G. V.; Sheikh, D. A.; Giles, D. C.


    In recent years, Composite Optics, Inc. (COI) has made significant advances in the use of graphite fiber reinforced composite (GFRC) materials for astronomical instrument applications. The inherent low density, high stiffness, and thermal stability makes GFRC a natural candidate for many astronomy applications. In order to reap these inherent benefits in astronomical applications, basic research has focused on material and process improvement. This has been accompanied by the design, fabrication, and test of several prototype reflectors that cover a broad wavelength spectrum of astronomical interests. The results of, and applications for, these efforts are summarized in the following list. X-Ray Carrier Shell: Innovative composite process yields accuracy and moisture stability. Demonstrated by vacuum optical test of 6" Wolter-I shell. Applicable to Con-X, etc. Lightweight Mirror Substrate for Visible Astronomy: Composite/glass hybrid design. Areal density Glass-like coating applied to composite. Polishable by conventional methods. Multiple six-inch substrates polished to 20 angstroms. Technology will enable future 5 kg/m2 visible to UV optics. 10 kg/m2 Submillimeter Reflector: Apertures to 5m possible with economical, all-composite mirror design, diffraction limited at 80 microns. Demonstrated with cryo-optical test (to 70K) of FIRST 2-meter prototype mirror. Applicable to FIRST and other IR astronomy. Large, Ultra-Stable Optical Support Structure: Uniform and near-zero CTE over broad dimensions. Demonstrated with cryo-optical test of 2-meter FIRST prototype. Applicable to NGST, SIM, LISSA. Ground Based Radio Telescope Reflector: Low-cost, accurate, stable, durable all-composite design for support structure & reflective surface. Demonstrated via fab & test of 3m adjustable and 5m static prototypes. Applicable to LMT, ALMA, etc. These recent accomplishments represent new enabling technologies to meet the needs of numerous astronomical instrument concepts. COI will

  18. Linking advanced fracture models to structural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Chiesa, Matteo


    Shell structures with defects occur in many situations. The defects are usually introduced during the welding process necessary for joining different parts of the structure. Higher utilization of structural materials leads to a need for accurate numerical tools for reliable prediction of structural response. The direct discretization of the cracked shell structure with solid finite elements in order to perform an integrity assessment of the structure in question leads to large size problems, and makes such analysis infeasible in structural application. In this study a link between local material models and structural analysis is outlined. An ''ad hoc'' element formulation is used in order to connect complex material models to the finite element framework used for structural analysis. An improved elasto-plastic line spring finite element formulation, used in order to take cracks into account, is linked to shell elements which are further linked to beam elements. In this way one obtain a global model of the shell structure that also accounts for local flexibilities and fractures due to defects. An important advantage with such an approach is a direct fracture mechanics assessment e.g. via computed J-integral or CTOD. A recent development in this approach is the notion of two-parameter fracture assessment. This means that the crack tip stress tri-axiality (constraint) is employed in determining the corresponding fracture toughness, giving a much more realistic capacity of cracked structures. The present thesis is organized in six research articles and an introductory chapter that reviews important background literature related to this work. Paper I and II address the performance of shell and line spring finite elements as a cost effective tool for performing the numerical calculation needed to perform a fracture assessment. In Paper II a failure assessment, based on the testing of a constraint-corrected fracture mechanics specimen under tension, is

  19. Advances on surface structural determination by LEED. (United States)

    Soares, Edmar A; de Castilho, Caio M C; de Carvalho, Vagner E


    In the last 40 years, low energy electron diffraction (LEED) has proved to be the most reliable quantitative technique for surface structural determination. In this review, recent developments related to the theory that gives support to LEED structural determination are discussed under a critical analysis of the main theoretical approximation-the muffin-tin calculation. The search methodologies aimed at identifying the best matches between theoretical and experimental intensity versus voltage curves are also considered, with the most recent procedures being reviewed in detail.

  20. Advances on surface structural determination by LEED

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Edmar A; De Carvalho, Vagner E [Departamento de Fisica, ICEX, Universidade Federal de Minas Gerais, 31270-090, Belo Horizonte, MG (Brazil); De Castilho, Caio M C, E-mail: [Grupo de Fisica de SuperfIcies e Materiais, Instituto de Fisica and Instituto Nacional de Ciencia e Tecnologia em Energia e Ambiente (CIENAM)INCT-E and A, Universidade Federal da Bahia, Campus Universitario da Federacao, 40170-115, Salvador, BA (Brazil)


    In the last 40 years, low energy electron diffraction (LEED) has proved to be the most reliable quantitative technique for surface structural determination. In this review, recent developments related to the theory that gives support to LEED structural determination are discussed under a critical analysis of the main theoretical approximation-the muffin-tin calculation. The search methodologies aimed at identifying the best matches between theoretical and experimental intensity versus voltage curves are also considered, with the most recent procedures being reviewed in detail. (topical review)

  1. AVHRR Composites = Advanced Very High Resolution Radiometer U.S. Alaska: 1989 - Present (United States)

    U.S. Geological Survey, Department of the Interior — Normalized Difference Vegetation Index (NDVI) Composites are produced from multiple Advanced Very High Resolution Radiometer (AVHRR) daily observations that have...

  2. Low-Cost Innovative Hi-Temp Fiber Coating Process for Advanced Ceramic Matrix Composites Project (United States)

    National Aeronautics and Space Administration — MATECH GSM (MG) proposes 1) to demonstrate a low-cost innovative Hi-Temp Si-doped in-situ BN fiber coating process for advanced ceramic matrix composites in order to...

  3. Comparison of Blepharoptosis Correction Using Müller-aponeurosis Composite Flap Advancement and Frontalis Muscle Transfer

    Directory of Open Access Journals (Sweden)

    David Dae Hawan Park, MD, PhD


    Conclusions: In our study, we confirmed that Müller aponeurosis composite flap advancement and the frontalis transfer technique are both effective in the correction of severe blepharoptosis; our results showed no significant differences between the 2 techniques.

  4. Advanced SiC-Matrix Composites with Improved Oxidation Resistance and Life Project (United States)

    National Aeronautics and Space Administration — The objective of this proposed effort is to demonstrate the promise of advanced C/SiC and SiC/SiC composites having improved environmental durability and longer life...

  5. Advanced Composite Bipolar Plate for Unitized Regenerative Fuel Cell/Electrolyzer Systems Project (United States)

    National Aeronautics and Space Administration — Development of an advanced composite bipolar plate is proposed for a unitized regenerative fuel cell and electrolyzer system that operates on pure feed streams...

  6. Advanced SiC composites for fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Snead, L.L.; Schwarz, O.J. [Oak Ridge National Lab., TN (United States)


    This is a short review of the motivation for and progress in the development of ceramic matrix composites for fusion. Chemically vapor infiltrated silicon carbide (SiC) composites have been fabricated from continuous fibers of either SiC or graphite and tested for strength and thermal conductivity. Of significance is the the Hi-Nicalon{trademark} SiC based fiber composite has superior unirradiated properties as compared to the standard Nicalon grade. Based on previous results on the stability of the Hi-Nicalon fiber, this system should prove more resistant to neutron irradiation. A graphite fiber composite has been fabricated with very good mechnical properties and thermal conductivity an order of magnitude higher than typical SiC/SiC composites.

  7. Advances in Seabed Liquefaction and its Implications for Marine Structures

    DEFF Research Database (Denmark)

    Sumer, B. Mutlu


    A review is presented of recent advances in seabed liquefaction and its implications for marine structures. The review is organized in seven sections: Residual liquefaction, including the sequence of liquefaction, mathematical modelling, centrifuge modelling and comparison with standard wave-flum......-flume results; Momentary liquefaction; Floatation of buried pipelines; Sinking of pipelines and marine objects; Liquefaction at gravity structures; Stability of rock berms in liquefied soils; and Impact of seismic-induced liquefaction.......A review is presented of recent advances in seabed liquefaction and its implications for marine structures. The review is organized in seven sections: Residual liquefaction, including the sequence of liquefaction, mathematical modelling, centrifuge modelling and comparison with standard wave...

  8. Advanced Sprayable Composite Coating for Cryogenic Insulation Project (United States)

    National Aeronautics and Space Administration — Advanced Materials Technology, Inc (AMTI) responds to the NASA solicitation X10 "Cryogenic Propellant Storage and Transfer" under subtopic X.01 "Cryogenic Fluid...

  9. Materials and structural aspects of advanced gas-turbine helicopter engines (United States)

    Freche, J. C.; Acurio, J.


    The key to improved helicopter gas turbine engine performance lies in the development of advanced materials and advanced structural and design concepts. The modification of the low temperature components of helicopter engines (such as the inlet particle separator), the introduction of composites for use in the engine front frame, the development of advanced materials with increased use-temperature capability for the engine hot section, can result in improved performance and/or decreased engine maintenance cost. A major emphasis in helicopter engine design is the ability to design to meet a required lifetime. This, in turn, requires that the interrelated aspects of higher operating temperatures and pressures, cooling concepts, and environmental protection schemes be integrated into component design. The major material advances, coatings, and design life-prediction techniques pertinent to helicopter engines are reviewed; the current state-of-the-art is identified; and when appropriate, progress, problems, and future directions are assessed.

  10. Multiscale Modeling of Advanced Materials for Damage Prediction and Structural Health Monitoring (United States)

    Borkowski, Luke

    Advanced aerospace materials, including fiber reinforced polymer and ceramic matrix composites, are increasingly being used in critical and demanding applications, challenging the current damage prediction, detection, and quantification methodologies. Multiscale computational models offer key advantages over traditional analysis techniques and can provide the necessary capabilities for the development of a comprehensive virtual structural health monitoring (SHM) framework. Virtual SHM has the potential to drastically improve the design and analysis of aerospace components through coupling the complementary capabilities of models able to predict the initiation and propagation of damage under a wide range of loading and environmental scenarios, simulate interrogation methods for damage detection and quantification, and assess the health of a structure. A major component of the virtual SHM framework involves having micromechanics-based multiscale composite models that can provide the elastic, inelastic, and damage behavior of composite material systems under mechanical and thermal loading conditions and in the presence of microstructural complexity and variability. Quantification of the role geometric and architectural variability in the composite microstructure plays in the local and global composite behavior is essential to the development of appropriate scale-dependent unit cells and boundary conditions for the multiscale model. Once the composite behavior is predicted and variability effects assessed, wave-based SHM simulation models serve to provide knowledge on the probability of detection and characterization accuracy of damage present in the composite. The research presented in this dissertation provides the foundation for a comprehensive SHM framework for advanced aerospace materials. The developed models enhance the prediction of damage formation as a result of ceramic matrix composite processing, improve the understanding of the effects of architectural and

  11. Progress in patch repair of aerospace composite structures (United States)

    Hou, Weiguo; Zhang, Weifang; Tang, Qingyun


    With the rapid application of the composite structure in the aerospace industry, more load-bearing structures and components are used with composites instead of conventional engineering materials. However, the composite structures are inevitably suffered damages in the complex environment, the composites structures repair become more important in the airplane maintenance. This paper describes the composites patch repair progress. Firstly, the flaws and damages concerned to composite structures are concluded, and also the repair principles are presented. Secondly, the advantages and disadvantages for different repair methods are analyzed, as well as the different bonded repair and their applicability to different structures is discussed. According the recent research in theory and experiment, the scarf repair effects under different parameters are analyzed. Finally, the failure mechanisms of repair structure are discussed, and some prospects are put forward.

  12. Advances in hadronic structure from Lattice QCD (United States)

    Constantinou, Martha


    Understanding nucleon structure is considered a milestone of hadronic physics and new facilities are planned devoted to its study. A future Electron-Ion-Collider proposed by the scientific community will greatly deepen our knowledge on the fundamental constituents of the visible world. To achieve this goal, a synergy between the experimental and theoretical sectors is imperative, and Lattice QCD is in a unique position to provide input from first principle calculations. In this talk we will discuss recent progress in nucleon structure from Lattice QCD, focusing on the evaluation of matrix elements using state-of-the-art simulations with pion masses at their physical value. The axial form factors, electromagnetic radii, the quark momentum fraction and the spin content of the nucleon will be discussed. We will also highlight quantities that may guide New Physics searches, such as the scalar and tensor charges. Finally, we will give updates on a new direct approach to compute quark parton distributions functions on the lattice.

  13. Influence of aromatic amine hardeners in the cure kinetics of an epoxy resin used in advanced composites

    Directory of Open Access Journals (Sweden)

    Michelle Leali Costa


    Full Text Available Composite structures for aerospace applications are mainly made by the well-known prepreg technology. In order to achieve adequate prepreg processing schedules, and consequently maximum fiber strength utilization, one has to know in deep the cure kinetics of matrix, which held the fibers together. This work describes a procedure to study the cure kinetic and has as example how aromatic amine hardeners influence the cure kinetics of an epoxy resin used in advanced composites. The investigation was carried out by using the DSC technique and it was found that depending on the system used the cure kinetics of the formulation obeys order n or autocatalytic order.

  14. Metal Matrix Composite Feedstock for Advanced Fiber Placement Process Project (United States)

    National Aeronautics and Space Administration — The proposed research pursues a path for reducing structural weight, increasing structural performance, and reducing fabrication cost while also minimizing...

  15. Advanced Composite Wind Turbine Blade Design Based on Durability and Damage Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Abumeri, Galib [AlphaSTAR Corporation, Long Beach, CA (United States); Abdi, Frank [AlphaSTAR Corporation, Long Beach, CA (United States)


    ). The use of nanoparticles lead to a delay in the onset of delamination. Load-displacement relationships obtained from testing of the blade with baseline neat material were compared to the ones from analytical simulation using neat resin and using silica nanoparticles in the resin. Multi-scale PFA results for the neat material construction matched closely those from test for both load displacement and location and type of damage and failure. AlphaSTAR demonstrated that wind blade structures made from advanced composite materials can be certified with multi-scale progressive failure analysis by following building block verification approach.


    Energy Technology Data Exchange (ETDEWEB)

    Galib Abumeri; Frank Abdi (PhD)


    ). The use of nanoparticles lead to a delay in the onset of delamination. Load-displacement relationships obtained from testing of the blade with baseline neat material were compared to the ones from analytical simulation using neat resin and using silica nanoparticles in the resin. Multi-scale PFA results for the neat material construction matched closely those from test for both load displacement and location and type of damage and failure. AlphaSTAR demonstrated that wind blade structures made from advanced composite materials can be certified with multi-scale progressive failure analysis by following building block verification approach.

  17. Composite structure of auxin response elements. (United States)

    Ulmasov, T; Liu, Z B; Hagen, G; Guilfoyle, T J


    The auxin-responsive soybean GH3 gene promoter is composed of multiple auxin response elements (AuxREs), and each AuxRE contributes incrementally to the strong auxin inducibility to the promoter. Two independent AuxREs of 25 bp (D1) and 32 bp (D4) contain the sequence TGTCTC. Results presented here show that the TGTCTC element in D1 and D4 is required but not sufficient for auxin inducibility in carrot protoplast transient expression assays. Additional nucleotides upstream of TGTCTC are also required for auxin inducibility. These upstream sequences showed constitutive activity and no auxin inducibility when part or all of the TGTCTC element was mutated or deleted. In D1, the constitutive element overlaps the 5' portion of TGTCTC; in D4, the constitutive element is separated from TGTCTC. An 11-bp element in D1, CCTCGTGTCTC, conferred auxin inducibility to a minimal cauliflower mosaic virus 35S promoter in transgenic tobacco seedlings as well as in carrot protoplasts (i.e., transient expression assays). Both constitutive elements bound specifically to plant nuclear proteins, and the constitutive element in D1 bound to a recombinant soybean basic leucine zipper transcription factor with G-box specificity. To demonstrate further the composite nature of AuxREs and the ability of the TGTCTC element to confer auxin inducibility, we created a novel AuxRE by placing a yeast GAL4 DNA binding site adjacent to the TGTCTC element. Expression of a GAL4-c-Rel transactivator in the presence of this novel AuxRE resulted in auxin-inducible expression. Our results indicate that at least some AuxREs have a composite structure consisting of a constitutive element adjacent to a conserved TGTCTC element that confers auxin inducibility.

  18. Summary of recent design studies of advanced acoustic-composite nacelles (United States)

    Norton, H. T., Jr.


    The results are summarized of recent NASA-sponsored studies of advanced acoustic-composite nacelles. Conceptual nacelle designs for current wide-bodied transports and for advanced technology transports, intended for operational use in the mid-1980's, were studied by Lockheed-California Company and the Douglas Aircraft Company. These studies were conducted with the objective of achieving significant reductions in community noise and/or fuel consumption with minimum penalties in airplane weights, cost, and operating expense. The results indicate that the use of advanced composite materials offer significant potential weight and cost savings and result in reduced fuel consumption and noise when applied to nacelles. The most promising concept for realizing all of these benefits was a long duct, mixed flow acoustic composite nacelle with advanced acoustic liners.

  19. Maximizing Student Alternatives: A Variable-Credit Advanced Composition Course. (United States)

    Laban, Lawrence F.

    This paper describes a variable-credit advanced writing course that allows non-English majors to set their own goals for writing and to develop specific writing skills that apply to their major fields. The course is a unitized sequence of three five-week sessions. The first session discusses the theoretical product model and process model for the…

  20. Study on voids of epoxy matrix composites sandwich structure parts (United States)

    He, Simin; Wen, Youyi; Yu, Wenjun; Liu, Hong; Yue, Cheng; Bao, Jing


    Void is the most common tiny defect of composite materials. Porosity is closely related to composite structure property. The voids forming behaviour in the composites sandwich structural parts with the carbon fiber reinforced epoxy resin skins was researched by adjusting the manufacturing process parameters. The composites laminate with different porosities were prepared with the different process parameter. The ultrasonic non-destructive measurement method for the porosity was developed and verified through microscopic examination. The analysis results show that compaction pressure during the manufacturing process had influence on the porosity in the laminate area. Increasing the compaction pressure and compaction time will reduce the porosity of the laminates. The bond-line between honeycomb core and carbon fiber reinforced epoxy resin skins were also analyzed through microscopic examination. The mechanical properties of sandwich structure composites were studied. The optimization process parameters and porosity ultrasonic measurement method for composites sandwich structure have been applied to the production of the composite parts.

  1. Recent advances and developments in composite dental restorative materials. (United States)

    Cramer, N B; Stansbury, J W; Bowman, C N


    Composite dental restorations represent a unique class of biomaterials with severe restrictions on biocompatibility, curing behavior, esthetics, and ultimate material properties. These materials are presently limited by shrinkage and polymerization-induced shrinkage stress, limited toughness, the presence of unreacted monomer that remains following the polymerization, and several other factors. Fortunately, these materials have been the focus of a great deal of research in recent years with the goal of improving restoration performance by changing the initiation system, monomers, and fillers and their coupling agents, and by developing novel polymerization strategies. Here, we review the general characteristics of the polymerization reaction and recent approaches that have been taken to improve composite restorative performance.

  2. Predictive Modeling of Complex Contoured Composite Structures Project (United States)

    National Aeronautics and Space Administration — The existing HDWLT (pictured) contoured composite structure design, its analyses and manufacturing tools, will be used to validate key analyses inputs through...

  3. Multi-material Preforming of Structural Composites

    Energy Technology Data Exchange (ETDEWEB)

    Norris, Robert E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Eberle, Cliff C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Pastore, Christopher M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sudbury, Thomas Z. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Xiong, Fue [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hartman, David [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)


    Fiber-reinforced composites offer significant weight reduction potential, with glass fiber composites already widely adopted. Carbon fiber composites deliver the greatest performance benefits, but their high cost has inhibited widespread adoption. This project demonstrates that hybrid carbon-glass solutions can realize most of the benefits of carbon fiber composites at much lower cost. ORNL and Owens Corning Reinforcements along with program participants at the ORISE collaborated to demonstrate methods for produce hybrid composites along with techniques to predict performance and economic tradeoffs. These predictions were then verified in testing coupons and more complex demonstration articles.

  4. Code qualification of structural materials for AFCI advanced recycling reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Li, M.; Majumdar, S.; Nanstad, R.K.; Sham, T.-L. (Nuclear Engineering Division); (ORNL)


    This report summarizes the further findings from the assessments of current status and future needs in code qualification and licensing of reference structural materials and new advanced alloys for advanced recycling reactors (ARRs) in support of Advanced Fuel Cycle Initiative (AFCI). The work is a combined effort between Argonne National Laboratory (ANL) and Oak Ridge National Laboratory (ORNL) with ANL as the technical lead, as part of Advanced Structural Materials Program for AFCI Reactor Campaign. The report is the second deliverable in FY08 (M505011401) under the work package 'Advanced Materials Code Qualification'. The overall objective of the Advanced Materials Code Qualification project is to evaluate key requirements for the ASME Code qualification and the Nuclear Regulatory Commission (NRC) approval of structural materials in support of the design and licensing of the ARR. Advanced materials are a critical element in the development of sodium reactor technologies. Enhanced materials performance not only improves safety margins and provides design flexibility, but also is essential for the economics of future advanced sodium reactors. Code qualification and licensing of advanced materials are prominent needs for developing and implementing advanced sodium reactor technologies. Nuclear structural component design in the U.S. must comply with the ASME Boiler and Pressure Vessel Code Section III (Rules for Construction of Nuclear Facility Components) and the NRC grants the operational license. As the ARR will operate at higher temperatures than the current light water reactors (LWRs), the design of elevated-temperature components must comply with ASME Subsection NH (Class 1 Components in Elevated Temperature Service). However, the NRC has not approved the use of Subsection NH for reactor components, and this puts additional burdens on materials qualification of the ARR. In the past licensing review for the Clinch River Breeder Reactor Project (CRBRP

  5. Damage Threshold Characterization in Structural Composite Materials and Composite Joints (United States)


    polyester, vinyl ester and epoxy, as reported earlier [1-3], the differences between resins are significant. The Vectorply ELT 5500 fabric (D) contains a...Delamination Testing,” AIAA Journal , vol. 28, 1990, pp. 1270-1276. 15. Agastra, P., "Mixed Mode Delamination of Glass Fiber/Polymer Matrix Composite

  6. Piezoelectric and mechanical properties of structured PZT-epoxy composites

    NARCIS (Netherlands)

    James, N.K.; Ende, D.A. van den; Lafont, U.; Zwaag, S. van der; Groen, W.A.


    Structured lead zirconium titanate (PZT)-epoxy composites are prepared by dielectrophoresis. The piezoelectric and dielectric properties of the composites as a function of PZT volume fraction are investigated and compared with the corresponding unstructured composites. The effect of poling voltage o

  7. Piezoelectric and mechanical properties of structured PZT–epoxy composites

    NARCIS (Netherlands)

    Kunnamkuzhakkal James, N.; Van den Ende, D.; Lafont, U.; Van der Zwaag, S.; Groen, W.A.


    Structured lead zirconium titanate (PZT)–epoxy composites are prepared by dielectrophoresis. The piezoelectric and dielectric properties of the composites as a function of PZT volume fraction are investigated and compared with the corresponding unstructured composites. The effect of poling voltage o

  8. Advanced accelerator and mm-wave structure research at LANL

    Energy Technology Data Exchange (ETDEWEB)

    Simakov, Evgenya Ivanovna [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    This document outlines acceleration projects and mm-wave structure research performed at LANL. The motivation for PBG research is described first, with reference to couplers for superconducting accelerators and structures for room-temperature accelerators and W-band TWTs. These topics are then taken up in greater detail: PBG structures and the MIT PBG accelerator; SRF PBG cavities at LANL; X-band PBG cavities at LANL; and W-band PBG TWT at LANL. The presentation concludes by describing other advanced accelerator projects: beam shaping with an Emittance Exchanger, diamond field emitter array cathodes, and additive manufacturing of novel accelerator structures.

  9. Mechanism Design and Testing of a Self-Deploying Structure Using Flexible Composite Tape Springs (United States)

    Footdale, Joseph N.; Murphey, Thomas W.


    The detailed mechanical design of a novel deployable support structure that positions and tensions a membrane optic for space imagining applications is presented. This is a complex three-dimensional deployment using freely deploying rollable composite tape spring booms that become load bearing structural members at full deployment. The deployment tests successfully demonstrate a new architecture based on rolled and freely deployed composite tape spring members that achieve simultaneous deployment without mechanical synchronization. Proper design of the flexible component mounting interface and constraint systems, which were critical in achieving a functioning unit, are described. These flexible composite components have much potential for advancing the state of the art in deployable structures, but have yet to be widely adopted. This paper demonstrates the feasibility and advantages of implementing flexible composite components, including the design details on how to integrate with required traditional mechanisms.

  10. Advances and trends in structural and solid mechanics; Proceedings of the Symposium, Washington, DC, October 4-7, 1982 (United States)

    Noor, A. K. (Editor); Housner, J. M.


    The mechanics of materials and material characterization are considered, taking into account micromechanics, the behavior of steel structures at elevated temperatures, and an anisotropic plasticity model for inelastic multiaxial cyclic deformation. Other topics explored are related to advances and trends in finite element technology, classical analytical techniques and their computer implementation, interactive computing and computational strategies for nonlinear problems, advances and trends in numerical analysis, database management systems and CAD/CAM, space structures and vehicle crashworthiness, beams, plates and fibrous composite structures, design-oriented analysis, artificial intelligence and optimization, contact problems, random waves, and lifetime prediction. Earthquake-resistant structures and other advanced structural applications are also discussed, giving attention to cumulative damage in steel structures subjected to earthquake ground motions, and a mixed domain analysis of nuclear containment structures using impulse functions.

  11. Peridynamics for analysis of failure in advanced composite materials

    KAUST Repository

    Askari, A.


    Peridynamics has been recently introduced as a way to simulate the initiation and propagation of multiple discontinuities (e.g. cracks). It is an alternative to classical continuum damage mechanics and fracture mechanics and is based on a nonlocal rewriting of the equilibrium equation. This new technique is particularly promising in the case of composite materials, in which very complex mechanisms of degradation must be described. We present here some fundamental aspects of peridynamics models for composite materials, and especially laminates. We also propose an approach to couple peridynamics domains with classical continuum mechanics (which relies on the concept of contact forces) by the use of a recently introduced coupling technique: the morphing technique, that appears to be a very versatile and powerful tool for coupling local to nonlocal descriptions.

  12. Composites structures for bone tissue reconstruction

    Energy Technology Data Exchange (ETDEWEB)

    Neto, W.; Santos, João [Universidade Federal de São Carlos, Departament of Materials Engineering - Rd. Washington Luis, Km 235, 13565-905, São Carlos-SP (Brazil); Avérous, L.; Schlatter, G.; Bretas, Rosario, E-mail: [Université de Strasbourg, ECPM-LIPHT - 25 rue Becquerel, 67087, Strasbourg (France)


    The search for new biomaterials in the bone reconstitution field is growing continuously as humane life expectation and bone fractures increase. For this purpose, composite materials with biodegradable polymers and hydroxyapatite (HA) have been used. A composite material formed by a film, nanofibers and HA has been made. Both, the films and the non-woven mats of nanofibers were formed by nanocomposites made of butylene adipate-co-terephthalate (PBAT) and HA. The techniques used to produce the films and nanofibers were spin coating and electrospinning, respectively. The composite production and morphology were evaluated. The composite showed an adequate morphology and fibers size to be used as scaffold for cell growth.

  13. Advanced analysis and design for fire safety of steel structures

    CERN Document Server

    Li, Guoqiang


    Advanced Analysis and Design for Fire Safety of Steel Structures systematically presents the latest findings on behaviours of steel structural components in a fire, such as the catenary actions of restrained steel beams, the design methods for restrained steel columns, and the membrane actions of concrete floor slabs with steel decks. Using a systematic description of structural fire safety engineering principles, the authors illustrate the important difference between behaviours of an isolated structural element and the restrained component in a complete structure under fire conditions. The book will be an essential resource for structural engineers who wish to improve their understanding of steel buildings exposed to fires. It is also an ideal textbook for introductory courses in fire safety for master’s degree programs in structural engineering, and is excellent reading material for final-year undergraduate students in civil engineering and fire safety engineering. Furthermore, it successfully bridges th...

  14. Advances in the Lightweight Air-Liquid Composite Heat Exchanger Development for Space Exploration Applications (United States)

    Shin, E. Eugene; Johnston, J. Chris; Haas, Daniel


    An advanced, lightweight composite modular Air/Liquid (A/L) Heat Exchanger (HX) Prototype for potential space exploration thermal management applications was successfully designed, manufactured, and tested. This full-scale Prototype consisting of 19 modules, based on recommendations from its predecessor Engineering Development unit (EDU) but with improved thermal characteristics and manufacturability, was 11.2 % lighter than the EDU and achieves potentially a 42.7% weight reduction from the existing state-of-the-art metallic HX demonstrator. However, its higher pressure drop (0.58 psid vs. 0.16 psid of the metal HX) has to be mitigated by foam material optimizations and design modifications including a more systematic air channel design. Scalability of the Prototype design was validated experimentally by comparing manufacturability and performance between the 2-module coupon and the 19-module Prototype. The Prototype utilized the thermally conductive open-cell carbon foam material but with lower density and adopted a novel high-efficiency cooling system with significantly increased heat transfer contact surface areas, improved fabricability and manufacturability compared to the EDU. Even though the Prototype was required to meet both the thermal and the structural specifications, accomplishing the thermal requirement was a higher priority goal for this first version. Overall, the Prototype outperformed both the EDU and the corresponding metal HX, particularly in terms of specific heat transfer, but achieved 93.4% of the target. The next generation Prototype to achieve the specification target, 3,450W would need 24 core modules based on the simple scaling factor. The scale-up Prototype will weigh about 14.7 Kg vs. 21.6 Kg for the metal counterpart. The advancement of this lightweight composite HX development from the original feasibility test coupons to EDU to Prototype is discussed in this paper.

  15. Advancing the Use of Secondary Inputs in Geopolymer Binders for Sustainable Cementitious Composites: A Review

    Directory of Open Access Journals (Sweden)

    Esther Obonyo


    Full Text Available Because of concerns over the construction industry‘s heavy use of cement and the general dissatisfaction with the performance of building envelopes with respect to durability, there is a growing demand for a novel class of ―green‖ binders. Geopolymer binders have re-emerged as binders that can be used as a replacement for Portland cement given their numerous advantages over the latter including lower carbon dioxide emissions, greater chemical and thermal resistance, combined with enhanced mechanical properties at both normal and extreme exposure conditions. The paper focuses on the use of geopolymer binders in building applications. It discusses the various options for starting materials and describes key engineering properties associated with geopolymer compositions that are ideal for structural applications. Specific properties, such as compressive strength, density, pore size distribution, cumulative water absorption, and acid resistance, are comparable to the specifications for structures incorporating conventional binders. This paper presents geopolymer binders, with their three dimensional microstructure, as material for structural elements that can be used to advance the realization of sustainable building systems.

  16. Scoring with composites : high performance sports technology harnessed to develop advanced oilpatch products

    Energy Technology Data Exchange (ETDEWEB)

    Smith, M.


    Fiberspar Corporation, a producer of high performance sporting goods, formed a partnership with Calgary-based Thread Tech Energy Systems Ltd. to launch a new advanced composite materials technology into the Canadian market. In 1986 Fiberspar developed its LinePipe product, a high-pressure, corrosion resistant pipe made in continuous lengths of up to eight kilometres. LinePipe consists of an inner thermoplastic pressure layer reinforced with high-strength glass or carbon fibres embedded in an epoxy matrix. It can be used for surface installations in production gathering and injection or disposal applications. A newly developed fibre-reinforced spoolable pipe is currently under development and undergoing field-testing as production tubing and coiled tubing to determine it s feasibility for permanent down-hole installations for completion orf corrosive production or injection wells, or for secondary completion of existing wells for gas-lift or velocity strings. In addition, another product called SmartPipe is also undergoing field trials. The SmartPipe incorporates fiber optics, copper signal wires, power cables and capillary tubes directly into the structural wall of the composite tubing during manufacturing. This intelligent wire provides real-time reservoir monitoring and data communication while moving oil and gas from downhole or on the surface for optimal reservoir treatments. 2 figs.

  17. Conceptual study on a new generation of the high-innovative advanced porous and composite nanostructural functional materials with nanofibers

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański


    Full Text Available Purpose: The purpose of the paper is to analyse theoretically the possibilities of the development of a new generation of the high-innovative advanced porous and composite nanostructural functional materials with nanofibers and to study into the material science grounds of synthesis and/or production and formulation of such materials’ structure and properties and to characterise and model their structure and properties depending on the compositional, phase and chemical composition and the applied synthesis and/or production and/or processing processes, without the attitude towards any direct practical application or use, but with confirming the highly probable future application areas, using the unexpected effects of formulating such materials’ functional properties.Design/methodology/approach: In general, the study is of priority cognitive importance as theoretical considerations and the author’s initial analyses related to technology foresight concerning this group of issues as well as sporadical results of research provided in the literature, usually in its incipient phase, indicating a great need to intensify scientific research, to develop the new groups of materials with quite unexpected predictable effects, resulting from the use of nanofibers for fabricating super advanced composite and porous materials.Findings: The description of the state of the art for the subject of the study has been limited to the issues initially selected with an analysis with the method of weighted scores.Practical implications: The outcoming materials may have direct influence on the development of electronics and photonics, medicine and pharmacy, environmental protection, automotive industry, space industry, machine industry, textile and clothing industry, cosmetic industry, agriculture and food sector.Originality/value: The value of this paper lies in the fact that it proposes a new generation of the high-innovative advanced porous and composite

  18. Hybrid Composite Structures: Multifunctionality through Metal Fibres

    NARCIS (Netherlands)

    Ahmed, T.


    The introduction of fibre reinforced polymer composites into the wings and fuselages of the newest aircraft are changing the design and manufacturing approach. Composites provide greater freedom to designers who want to improve aircraft performance in an affordable way. In this quest, researchers ar

  19. The structural damping of composite beams with tapered boundaries (United States)

    Coni, M.; Benchekchou, B.; White, R. G.


    Most metallic and composite structures of conventional construction are lightly damped. It is obviously advantageous, in terms of response to in-service dynamic loading, if damping can be increased with minimal weight addition. This report describes finite element analyses and complementary experiments carried out on composite, carbon fiber reinforced plastic, beams with tapered boundaries composed of layers of highly damped composite material. It is shown that modal damping of the structure may be significantly increased by this method.

  20. Recent Advances In Optimization Of Aerospace Structures And Engines (United States)

    Rao*, J. S.

    Optimization theories have been well advanced during the last few decades; however when it came to handle real life engineering structures it has been always time consuming and approximate when the structure geometry is highly complex. Design of Experiments has helped in understanding the influence of size and shape parameters on achieving a specified objective function with required constraints and a suitable analysis platform, but has its limitations in arriving at the final optimal solution. There are several commercial codes that addressed this need to handle large size structures subjected to dynamic loads. Most advanced tools in this category are Altair OptiStruct and Altair HyperStudy available in Altair HyperWorks suite. Application of these tools in achieving optimum solutions for linear advanced aircraft structures for minimization of weight are first explained. The application of these tools for globally elastic and locally plastic nonlinear structures to reduce local plastic strains and achieve higher life under dynamic loads will then be discussed.

  1. Advances in PAS-2 thermoplastic prepregs and composites

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.M.; Register, D.F.; Lindstrom, M.R.; Campbell, R.W.


    A family of polyarylene sulfide polymers is being developed as thermoplastic engineering resins. These resins have high temperature mechanical performance, good mechanical strength, and good solvent resistance. The newest member of this family of resins is PAS-2 amorphous polyarylene sulfide. One potential application for this amorphous resin is as a matrix for high performance composites. The amorphous polyarylene sulfide resin has been formed into unidirectional prepreg tapes. These tapes have been molded into laminates of excellent quality. Recently, new levels of performance in mechanical properties and processing have been achieved.

  2. Braided Composite Technologies for Rotorcraft Structures Project (United States)

    National Aeronautics and Space Administration — The Phase 2 effort will be used to advance the material and design technologies that were explored in the Phase 1 study of hybrid gears. In this hybrid approach, the...

  3. Braided Composite Technologies for Rotorcraft Structures Project (United States)

    National Aeronautics and Space Administration — The proposed program will focus on the development of a new generation of advanced technology for rotorcraft transmission systems. This program will evaluate the...

  4. Progressive fracture of polymer matrix composite structures: A new approach (United States)

    Chamis, C. C.; Murthy, P. L. N.; Minnetyan, L.


    A new approach independent of stress intensity factors and fracture toughness parameters has been developed and is described for the computational simulation of progressive fracture of polymer matrix composite structures. The damage stages are quantified based on physics via composite mechanics while the degradation of the structural behavior is quantified via the finite element method. The approach account for all types of composite behavior, structures, load conditions, and fracture processes starting from damage initiation, to unstable propagation and to global structural collapse. Results of structural fracture in composite beams, panels, plates, and shells are presented to demonstrate the effectiveness and versatility of this new approach. Parameters and guidelines are identified which can be used as criteria for structural fracture, inspection intervals, and retirement for cause. Generalization to structures made of monolithic metallic materials are outlined and lessons learned in undertaking the development of new approaches, in general, are summarized.

  5. The use of advanced computer simulation in structural design

    Energy Technology Data Exchange (ETDEWEB)

    Field, C.J.; Mole, A. [Arup, San Fransisco, CA (United States); Arkinstall, M. [Arup, Sydney (Australia)


    The benefits that can be gained from the application of advanced numerical simulation in building design were discussed. A review of current practices in structural engineering was presented along with an illustration of a range of international project case studies. Structural engineers use analytical methods to evaluate both static and dynamic loads. Structural design is prescribed by a range of building codes, depending on location, building type and loading, but often, buildings do not fit well within the codes, particularly if one wants to take advantage of new technologies and developments in design that are not covered by the code. Advanced simulation refers to the use of mathematical modeling to complex problems to allow a wider consideration of building types and conditions that can be designed reliably using standard practices. Advanced simulation is used to address virtual testing and prototyping, verifying innovative design ideas, forensic engineering, and design optimization. The benefits of advanced simulation include enhanced creativity, improved performance, cost savings, risk management, sustainable design solutions, and better communication. The following 5 case studies illustrated the value gained by using advanced simulation as an integral part of the design process: the earthquake resistant Maison Hermes in Tokyo; the seismic resistant braces known as the Unbonded Brace for use in the United States; a simulation of the existing Disney Museum to evaluate its capacity to resist earthquakes; simulation of the MIT Brain and Cognitive Science Project to evaluate the effect of different foundation types on the vibration entering the building; and, the Beijing Aquatic Center whose design was streamlined by optimized structural analysis. It was suggested that industry should encourage the transfer of technology from other professions and should try to collaborate towards a global building model to construct buildings in a more efficient manner. 7 refs

  6. Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components (United States)

    Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna; Kiser, Doug; Wiesner, Valerie L.


    This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiCSiC Ceramic Matrix Composite (CMC) components for next generation turbine engines. The emphasis has been placed on the current design challenges of the 2700F environmental barrier coatings; coating processing and integration with SiCSiC CMCs and component systems; and performance evaluation and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements through advanced compositions and architecture designs, as shown in recent simulated engine high heat flux, combustion environment, in conjunction with mechanical creep and fatigue loading testing conditions.

  7. Differently Structured Advance Organizers Lead to Different Initial Schemata and Learning Outcomes (United States)

    Gurlitt, Johannes; Dummel, Sebastian; Schuster, Silvia; Nuckles, Matthias


    Does the specific structure of advance organizers influence learning outcomes? In the first experiment, 48 psychology students were randomly assigned to three differently structured advance organizers: a well-structured, a well-structured and key-concept emphasizing, and a less structured advance organizer. These were followed by a sorting task, a…

  8. Development of Biobased Composites of Structural Quality (United States)

    Taylor, Christopher Alan

    Highly biobased composites with properties and costs rivaling those consisting of synthetic constituents are a goal of much current research. The obvious material choices, vegetable oil based resins and natural fibers, present the challenges of poor resin properties and weak fiber/matrix bonding, respectively. Conventional methods of overcoming poor resin quality involve the incorporation of additives, which dilutes the resulting composite's bio-content and increases cost. To overcome these limitations while maintaining high bio-content and low cost, epoxidized sucrose soyate is combined with surface-treated flax fiber to produce biocomposites. These composites are fabricated using methods emphasizing scalability and efficiency, for cost effectiveness of the final product. This approach resulted in the successful production of biocomposites having properties that meet or exceed those of conventional pultruded members. These properties, such as tensile and flexural strengths of 223 and 253 MPa, respectively, were achieved by composites having around 85% bio-content.

  9. Structural Composites Corrosive Management by Computational Simulation (United States)

    Chamis, Christos C.; Minnetyan, Levon


    A simulation of corrosive management on polymer composites durability is presented. The corrosive environment is assumed to manage the polymer composite degradation on a ply-by-ply basis. The degradation is correlated with a measured Ph factor and is represented by voids, temperature, and moisture which vary parabolically for voids and linearly for temperature and moisture through the laminate thickness. The simulation is performed by a computational composite mechanics computer code which includes micro, macro, combined stress failure, and laminate theories. This accounts for starting the simulation from constitutive material properties and up to the laminate scale which exposes the laminate to the corrosive environment. Results obtained for one laminate indicate that the ply-by-ply managed degradation degrades the laminate to the last one or the last several plies. Results also demonstrate that the simulation is applicable to other polymer composite systems as well.

  10. Lightweight, Composite Cryogenic Tank Structures Project (United States)

    National Aeronautics and Space Administration — Microcosm has developed and qualified strong, all-composite LOX tanks for launch vehicles. Our new 42-inch diameter tank design weighs 486 lbs and burst without...

  11. In situ cure monitoring of advanced fiber reinforced composites (United States)

    Powell, Graham R.; Crosby, Peter A.; Fernando, Gerard F.; France, Chris M.; Spooncer, Ronald C.; Waters, David N.


    This paper describes a comparative study of in-situ cure monitoring and cure modelling by three methods: (a) evanescent wave spectroscopy, (b) refractive index change, (c) near- infrared spectroscopy. Optical fibers were embedded into aerospace epoxy resins during the manufacturing process of the composite. The cure characteristics were then tracked in real- time during the processing of the material via evanescent wave interaction. This technique is based upon monitoring of characteristic infrared absorption bands of the resin system to find the concentration of the epoxy and amine hardener as a function of cure time. Hence this technique is suitable for on-line process monitoring and optimization. Results obtained from the optical fiber sensors were used to model the curing behavior of the resin system. The results were compared with near-infrared spectroscopy and differential scanning calorimetry experiments carried out under similar conditions. The feasibility of utilizing refractive index changes to monitor the extent of cure has also been demonstrated.

  12. Damage Prediction Models for Advanced Materials and Composites (United States)

    Xie, Ming; Ahmad, Jalees; Grady, Joseph E. (Technical Monitor)


    In the present study, the assessment and evaluation of various acoustic tile designs were conducted using three-dimensional finite element analysis, which included static analysis, thermal analysis and modal analysis of integral and non-integral tile design options. Various benchmark specimens for acoustic tile designs, including CMC integral T-joint and notched CMC plate, were tested in both room and elevated temperature environment. Various candidate ceramic matrix composite materials were used in the numerical modeling and experimental study. The research effort in this program evolved from numerical modeling and concept design to a combined numerical analysis and experimental study. Many subjects associated with the design and performance of the acoustic tile in jet engine exhaust nozzle have been investigated.

  13. Composite Materials and Sandwich Structures - A Primer (United States)


    quality and protects prepreg from handling damage. Non - woven unidirectional tapes can otherwise split between fibers. Clean, white lint-free cotton ...applications and S glass fibers are used in strength critical situations. S glass fibers are sometimes woven in composite materials to increase toughness...A woven form of the reinforcements (Figure 1b) is also used in certain cases, depending on the application of the composite. Figure 1a- Fiber

  14. Research on Composite Materials for Structural Design. (United States)


    Residual Stresses in Composite Laminates", (August 1983); the M.Sc. thesis of E.J. Porth , titled "Effect of an External Stress on Moisture Diffusion in...Rates in OUnidirectional Double Cantilevered Beam Fracture Toughness Specimens", December 1982. 4. Porth , E.J., "Effect of an External Stress on...Composite Materials (December 1983) Edward John Porth , B.S., University of Colorado Chairman of Advisory Committee: Dr. Y. Weitsman This work concerns

  15. Photo-excited terahertz switch based on composite metamaterial structure (United States)

    Wang, Guocui; Zhang, Jianna; Zhang, Bo; He, Ting; He, Yanan; Shen, Jingling


    A photo-excited terahertz switch based on a composite metamaterial structure was designed by integration of photoconductive silicon into the gaps of split-ring resonators. The conductivity of the silicon that was used to fill the gaps in the split-ring resonators was tuned dynamically as a function of the incident pump power using laser excitation, leading to a change in the composite metamaterial structure's properties. We studied the transmission characteristics of the composite metamaterial structure for various silicon conductivities, and the results indicated that this type of composite metamaterial structure could be used as a resonance frequency tunable terahertz metamaterial switch. We also designed other structures by filling different gaps with silicon, and proved that these structures could be used as terahertz metamaterial switches can change the working mode from a single frequency to multiple frequencies.

  16. NATO Advanced Research Workshop on Vectorization of Advanced Methods for Molecular Electronic Structure

    CERN Document Server


    That there have been remarkable advances in the field of molecular electronic structure during the last decade is clear not only to those working in the field but also to anyone else who has used quantum chemical results to guide their own investiga­ tions. The progress in calculating the electronic structures of molecules has occurred through the truly ingenious theoretical and methodological developments that have made computationally tractable the underlying physics of electron distributions around a collection of nuclei. At the same time there has been consider­ able benefit from the great advances in computer technology. The growing sophistication, declining costs and increasing accessibi­ lity of computers have let theorists apply their methods to prob­ lems in virtually all areas of molecular science. Consequently, each year witnesses calculations on larger molecules than in the year before and calculations with greater accuracy and more com­ plete information on molecular properties. We can surel...

  17. Woven Structures from Natural Fibres for Reinforcing Composites


    Maniņš, M; Bernava, A; Strazds, G.


    The increase of production of woven structures from natural fibres for reinforced composites can be noticed in different sectors of economy. This can be explained by limited sources of raw materials and different environmental issues, as well as European Union guidelines for car manufacture [4]. This research produced 2D textile structures of hemp yarn and polypropylene yarn and tested the impact of added glass fibre yarn on the mechanical properties of the woven structures and the composites...

  18. Composition-structure-property relation of oxide glasses

    DEFF Research Database (Denmark)

    Hermansen, Christian

    The composition of glass can be varied continuously within their glass-forming regions. This compositional flexibility makes it possible to tailor the properties of a glass for a variety of specific uses. In the industry such tailoring is done on a trial-and-error basis with only the intuition...... also increases such properties. Yet, these rules are not strictly followed even for the simplest binary oxide glasses, such as alkali silicates, borates and phosphates. In this thesis it is argued that the missing link between composition and properties is the glass structure. Structural models...... capable of ab initio prediction of the oxide glass properties from composition....

  19. Impact of leachate composition on the advanced oxidation treatment. (United States)

    Oulego, Paula; Collado, Sergio; Laca, Adriana; Díaz, Mario


    Advanced oxidation processes (AOPs) are gaining importance as an alternative to the biological or physicochemical treatments for the management of leachates. In this work, it has been studied the effect of the characteristics of the leachate (content in humic acids, landfill age and degree of stabilization) on the wet oxidation process and final quality of the treated effluent. A high concentration of humic acids in the leachate had a positive effect on the COD removal because this fraction is more easily oxidizable. Additionally, it has been demonstrated that the simultaneous presence of humic acid and the intermediates generated during the oxidation process improved the degradation of this acid, since such intermediates are stronger initiators of free radicals than the humic acid itself. Similar values of COD removals (49% and 51%) and biodegradability indices (0.30 and 0.35) were observed, after 8 h of wet oxidation, for the stabilised leachate (biologically pretreated) and the raw one, respectively. Nevertheless, final colour removal was much higher for the stabilised leachate, achieving values up to 91%, whereas for the raw one only 56% removal was attained for the same reaction time. Besides, wet oxidation treatment was more efficient for the young leachate than for the old one, with final COD conversions of 60% and 37%, respectively. Eventually, a triangular "three-lump" kinetic model, which considered direct oxidation to CO2 and partial oxidation through intermediate compounds, was here proposed.

  20. Structural Ceramic Composites for Nuclear Applications

    Energy Technology Data Exchange (ETDEWEB)

    William Windes; P.A. Lessing; Y. Katoh; L. L. Snead; E. Lara-Curzio; J. Klett; C. Henager, Jr.; R. J. Shinavski


    A research program has been established to investigate fiber reinforced ceramic composites to be used as control rod components within a Very High Temperature Reactor. Two candidate systems have been identified, carbon fiber reinforced carbon (Cf/C) and silicon carbide fiber reinforced silicon carbide (SiCf/SiC) composites. Initial irradiation stability studies to determine the maximum dose for each composite type have been initiated within the High Flux Isotope Reactor at Oak Ridge National Laboratory. Test samples exposed to 10 dpa irradiation dose have been completed with future samples to dose levels of 20 and 30 dpa scheduled for completion in following years. Mechanical and environmental testing is being conducted concurrently at the Idaho National Laboratory and at Pacific Northwest National Laboratory. High temperature test equipment, testing methodologies, and test samples for high temperature (up to 1600º C) tensile strength and long duration creep studies have been established. Specific attention was paid to the architectural fiber preform design as well as the materials used in construction of the composites. Actual testing of both tubular and flat, "dog-bone" shaped tensile composite specimens will begin next year. Since there is no precedence for using ceramic composites within a nuclear reactor, ASTM standard test procedures will be established from these mechanical and environmental tests. Close collaborations between the U.S. national laboratories and international collaborators (i.e. France and Japan) are being forged to establish both national and international test standards to be used to qualify ceramic composites for nuclear reactor applications.

  1. Three-axis distributed fiber optic strain measurement in 3D woven composite structures (United States)

    Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David


    Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading.

  2. Three-Axis Distributed Fiber Optic Strain Measurement in 3D Woven Composite Structures (United States)

    Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David


    Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading. Keywords: fiber optic, distributed strain sensing, Rayleigh scatter, optical frequency domain reflectometry

  3. Metallic Functionally Graded Materials: A Specific Class of Advanced Composites

    Institute of Scientific and Technical Information of China (English)

    Jerzy J.Sobczak; Ludmil Drenchev


    Functionally graded materials,including their characterization,properties and production methods are a new rapidly developing field of materials science.The aims of this review are to systematize the basic production techniques for manufacturing functionally graded materials.Attention is paid to the principles for obtaining graded structure mainly in the metal based functionally graded materials.Several unpublished results obtained by the authors have been discussed briefly.Experimental methods and theoretical analysis for qualitative and quantitative estimation of graded properties have also been presented.The article can be useful for people who work in the field of functionally graded structures and materials,and who need a compact informative review of recent experimental and theoretical activity in this area.

  4. Advanced composite elevator for Boeing 727 aircraft, volume 2 (United States)

    Chovil, D. V.; Grant, W. D.; Jamison, E. S.; Syder, H.; Desper, O. E.; Harvey, S. T.; Mccarty, J. E.


    Preliminary design activity consisted of developing and analyzing alternate design concepts and selecting the optimum elevator configuration. This included trade studies in which durability, inspectability, producibility, repairability, and customer acceptance were evaluated. Preliminary development efforts consisted of evaluating and selecting material, identifying ancillary structural development test requirements, and defining full scale ground and flight test requirements necessary to obtain Federal Aviation Administration (FAA) certification. After selection of the optimum elevator configuration, detail design was begun and included basic configuration design improvements resulting from manufacturing verification hardware, the ancillary test program, weight analysis, and structural analysis. Detail and assembly tools were designed and fabricated to support a full-scope production program, rather than a limited run. The producibility development programs were used to verify tooling approaches, fabrication processes, and inspection methods for the production mode. Quality parts were readily fabricated and assembled with a minimum rejection rate, using prior inspection methods.

  5. Engineering Effects of Advanced Composite Materials on Avionics. (United States)


    Keywords: Antennas, Structures Article (1979) Prepared by H. L. Staubs , G. G. Chadwick, A. A. Woods Company: USAF/Lockheed (Presented at the National...Schulte, 67 Freeman, 58 Sidwell, 7 Furktow, 17 Siegel, 56 Gajda, 19, 61, 64 Skouby, 33, 66 Greenwell, 84, 85, 86, 88 Smithers, 63 Harder, 84, 87 Staubs ...potential of the building with respect to the earth may fluc- faults constitute personnel, fire, and explosion hazards which tuate widely. The

  6. Properties of fiber composites for advanced flywheel energy storage devices

    Energy Technology Data Exchange (ETDEWEB)

    DeTeresa, S J; Groves, S E


    The performance of commercial high-performance fibers is examined for application to flywheel power supplies. It is shown that actual delivered performance depends on multiple factors such as inherent fiber strength, strength translation and stress-rupture lifetime. Experimental results for recent stress-rupture studies of carbon fibers will be presented and compared with other candidate reinforcement materials. Based on an evaluation of all of the performance factors, it is concluded that carbon fibers are preferred for highest performance and E-glass fibers for lowest cost. The inferior performance of the low-cost E-glass fibers can be improved to some extent by retarding the stress-corrosion of the material due to moisture and practical approaches to mitigating this corrosion are discussed. Many flywheel designs are limited not by fiber failure, but by matrix-dominated failure modes. Unfortunately, very few experimental results for stress-rupture under transverse tensile loading are available. As a consequence, significant efforts are made in flywheel design to avoid generating any transverse tensile stresses. Recent results for stress-rupture of a carbon fiber/epoxy composite under transverse tensile load reveal that these materials are surprisingly durable under the transverse loading condition and that some radial tensile stress could be tolerated in flywheel applications.

  7. Overview of an Advanced Hypersonic Structural Concept Test Program (United States)

    Stephens, Craig A.; Hudson, Larry D.; Piazza, Anthony


    This viewgraph presentation provides an overview of hypersonics M&S advanced structural concepts development and experimental methods. The discussion on concepts development includes the background, task objectives, test plan, and current status of the C/SiC Ruddervator Subcomponent Test Article (RSTA). The discussion of experimental methods examines instrumentation needs, sensors of interest, and examples of ongoing efforts in the development of extreme environment sensors.

  8. A formal structure for advanced automatic flight-control systems (United States)

    Meyer, G.; Cicolani, L. S.


    Techniques were developed for the unified design of multimode, variable authority automatic flight-control systems for powered-lift STOL and VTOL aircraft. A structure for such systems is developed to deal with the strong nonlinearities inherent in this class of aircraft, to admit automatic coupling with advanced air traffic control, and to admit a variety of active control tasks. The aircraft being considered is the augmentor wing jet STOL research aircraft.

  9. Preface: Advanced Thin Film Developments and Nano Structures

    Institute of Scientific and Technical Information of China (English)

    Ray Y.Lin


    @@ In this special issue, we invited a few leading materials researchers to present topics in thin films, coatings, and nano structures. Readers will find most recent developments in topics, including recent advances in hard, tough, and low friction nanocomposite coatings; thin films for coating nanomaterials; electroless plating of silver thin films on porous Al2O3 substrate; CrN/Nano Cr interlayer coatings; nano-structured carbide derived carbon (CDC) films and their tribology; predicting interdiffusion in high-temperature coatings; gallium-catalyzed silica nanowire growth; and corrosion protection properties of organofunctional silanes. Authors are from both national laboratories and academia.

  10. Advanced modeling of thermal NDT problems: from buried landmines to defects in composites (United States)

    Vavilov, Vladimir P.; Burleigh, Douglas D.; Klimov, Alexey G.


    Advanced thermal models that can be used in the detection of buried landmines and the TNDT (thermographic nondestructive testing) of composites are discussed. The interdependence between surface temperature signals and various complex parameters, such as surface and volumetric moisture, the shape of a heat pulse, material anisotropy, etc., is demonstrated.

  11. Variation in Content Coverage by Classroom Composition: An Analysis of Advanced Math Course Content (United States)

    Covay, Elizabeth


    Everyone knows that there is racial inequality in achievement returns from advanced math; however, they do not know why black students and white students taking the same level of math courses are not leaving with the same or comparable skill levels. To find out, the author examines variation in course coverage by the racial composition of the…

  12. The Irony and the Ecstasy: How Holden Caulfield Helped My Advanced Composition Students Find Their Voices. (United States)

    Huff, Linda

    An instructor of an advanced composition course (adapted from one taught by James Seitz at the University of Pittsburgh) at the University of California Riverside took her students through a series of reading and writing assignments that asked them to "engage in a wide variety of prose styles and...consider what style suggests about language,…

  13. Detection of disbonds in a honeycomb composite structure using guided waves (United States)

    Baid, Harsh; Banerjee, Sauvik; Joshi, Shiv; Mal, Siddhartha


    Advanced composites are being used increasingly in state-of-the-art aircraft and aerospace structures. In spite of their many advantages composite materials are highly susceptible to hidden flaws that may occur at any time during the life cycle of a structure and if undetected, may cause sudden and catastrophic failure of the entire structure. An example of such a defects critical structural component is the "honeycomb composite" in which thin composite skins are bonded with adhesives to the two faces of extremely lightweight and relatively thick metallic honeycombs. These components are often used in aircraft and aerospace structures due to their high strength to weight ratio. Unfortunately, the bond between the honeycomb and the skin may degrade with age and service loads leading to separation of the load-bearing skin from the honeycomb (called "disbonds") and compromising the safety of the structure. This paper is concerned with the noninvasive detection of disbonds using ultrasonic guided waves. Laboratory experiments are carried out on a composite honeycomb specimen containing localized disbonded regions. Ultrasonic waves are launched into the specimen using a broadband PZT transducer and are detected by a distributed array of identical transducers located on the surface of the specimen. The guided wave components of the signals are shown to be very strongly influenced by the presence of a disbond. The experimentally observed results are being used to develop an autonomous scheme to locate the disbonds and to estimate their size.

  14. Active Structural Fibers for Multifunctional Composite Materials (United States)


    31, 2012 X - ray Diffraction of BST Coatings • BaxSr1-xTiO3 films can be grown with stoichiometry control • Process allows for control of the film...thickness from ~500nm to 20mm •Other perovskite compositions can be synthesized 2q Henry A Sodano – AFOSR Mech. of Multifunctional and

  15. Nano-structured polymer composites and process for preparing same (United States)

    Hillmyer, Marc; Chen, Liang


    A process for preparing a polymer composite that includes reacting (a) a multi-functional monomer and (b) a block copolymer comprising (i) a first block and (ii) a second block that includes a functional group capable of reacting with the multi-functional monomer, to form a crosslinked, nano-structured, bi-continuous composite. The composite includes a continuous matrix phase and a second continuous phase comprising the first block of the block copolymer.

  16. Code qualification of structural materials for AFCI advanced recycling reactors.

    Energy Technology Data Exchange (ETDEWEB)

    Natesan, K.; Li, M.; Majumdar, S.; Nanstad, R.K.; Sham, T.-L. (Nuclear Engineering Division); (ORNL)


    This report summarizes the further findings from the assessments of current status and future needs in code qualification and licensing of reference structural materials and new advanced alloys for advanced recycling reactors (ARRs) in support of Advanced Fuel Cycle Initiative (AFCI). The work is a combined effort between Argonne National Laboratory (ANL) and Oak Ridge National Laboratory (ORNL) with ANL as the technical lead, as part of Advanced Structural Materials Program for AFCI Reactor Campaign. The report is the second deliverable in FY08 (M505011401) under the work package 'Advanced Materials Code Qualification'. The overall objective of the Advanced Materials Code Qualification project is to evaluate key requirements for the ASME Code qualification and the Nuclear Regulatory Commission (NRC) approval of structural materials in support of the design and licensing of the ARR. Advanced materials are a critical element in the development of sodium reactor technologies. Enhanced materials performance not only improves safety margins and provides design flexibility, but also is essential for the economics of future advanced sodium reactors. Code qualification and licensing of advanced materials are prominent needs for developing and implementing advanced sodium reactor technologies. Nuclear structural component design in the U.S. must comply with the ASME Boiler and Pressure Vessel Code Section III (Rules for Construction of Nuclear Facility Components) and the NRC grants the operational license. As the ARR will operate at higher temperatures than the current light water reactors (LWRs), the design of elevated-temperature components must comply with ASME Subsection NH (Class 1 Components in Elevated Temperature Service). However, the NRC has not approved the use of Subsection NH for reactor components, and this puts additional burdens on materials qualification of the ARR. In the past licensing review for the Clinch River Breeder Reactor Project (CRBRP

  17. Stiff, Strong Splice For A Composite Sandwich Structure (United States)

    Schmaling, D.


    New type of splice for composite sandwich structure reduces peak shear stress in structure. Layers of alternating fiber orientation interposed between thin ears in adhesive joint. Developed for structural joint in spar of helicopter rotor blade, increases precision of control over thickness of adhesive at joint. Joint easy to make, requires no additional pieces, and adds little weight.

  18. Advanced topics on rotor blade full-scale structural fatigue testing and requirements

    DEFF Research Database (Denmark)

    Berring, Peter; Fedorov, Vladimir; Belloni, Federico

    further developed since then. Structures in composite materials are generally difficult and time consuming to test for fatigue resistance. Therefore, several methods for testing of blades have been developed and exist today. Those methods are presented in [1]. This report deals with more advanced topics...... for fatigue testing of wind turbine blades. One challenge is how to fatigue test blades under realistic conditions. In order to study this topic a finite element based multibody formulation using the floating frame of reference approach is used to study fatigue loading under different external conditions...

  19. Structural arrangement trade study. Volume 3: Reusable Hydrogen Composite Tank System (RHCTS) and Graphite Composite Primary Structures (GCPS). Addendum (United States)


    This volume is the third of a 3 volume set that addresses the structural trade study plan that will identify the most suitable structural configuration for an SSTO winged vehicle capable of delivering 25,000 lbs to a 220 nm circular orbit at 51.6 deg inclination. The most suitable Reusable Hydrogen Composite Tank System (RHCTS), and Graphite Composite Tank System (GCPS) composite materials for intertank, wing and thrust structures are identified. Vehicle resizing charts, selection criteria and back-up charts, parametric costing approach and the finite element method analysis are discussed.

  20. Composite Structure Monitoring using Direct Write Sensors Project (United States)

    National Aeronautics and Space Administration — This NASA SBIR Phase II project seeks to develop and demonstrate a suite of sensor products to monitor the health of composite structures. Sensors will be made using...

  1. Inside-Out Manufacturing of Composite Structures Project (United States)

    National Aeronautics and Space Administration — Demonstrate the inside-out manufacturing process by manufacturing a complex shaped composite structure with imbedded wiring and fluid handling without the use of a...

  2. Composite materials applied to the E-ELT structure (United States)

    Pajuelo, Eugenio; Gómez, José Ramón; Ronquillo, Bernardo; Brunetto, Enzo; Koch, Fran


    The upper part of the European Extremely Large Telescope (E-ELT) altitude structure is one of the most critical areas of the telescope's structure. This part hosts sensitive optical elements of the telescope. Its structural performance has a major impact on the whole system. The most critical requirements are low optical path obscuration, high static and dynamic performance (high specific modulus), high mechanical safety (high specific strength), low wind cross section and low weight. Composite materials are ideally suited to meet these requirements. This study is carried out in order to quantify the relative advantage of composite material over mild steel, in terms of performance and costs. The mechanical behavior of the steel structure can be easily improved with a structure manufactured with composite materials. This structure is significantly lighter than the steel one and reduces relative displacements between primary and secondary mirror. Consequently, optical performance is improved, assembly process is simplified and transport cost is reduced.

  3. Freshman Students‟ Attitudes and Behavior towards Advanced Grammar and Composition Teaching

    Directory of Open Access Journals (Sweden)

    Romel M. Aceron


    Full Text Available Teaching English advanced grammar and composition to college students is important as it provides them with high level of understanding and competence in the language. It guides them in putting words together into sentences and makes them orally produce sounds clearly and effectively. This paper aims to determine the attitudes and behavior towards advanced grammar and composition teaching among freshman college students of Batangas State University. Descriptive method of research has been used to analyze and interpret data. The following instruments such as self-made questionnaire, focus group discussion, data analysis, interview guide, have been utilized to gather data. To analyze and interpret data, mean scores have been used. Pearson’s (r Product Moment Correlation Method has been utilized to treat the null hypothesis with regard to the attitudes and behavior of the students towards advanced grammar and composition teaching. Based on the findings of the study, the students sometimes understand and feel the subject matters, i.e., morphology, phonology, grammar and usage, and mechanics and composition writing. They are also sometimes ready in particular lesson and activity which are given to them in class. The study also reveals that there is no significant relationship between the students’ attitudes and behavior towards AGCT. In this regard, college students taking advanced grammar and composition course must be well-motivated to understand, and must have the readiness to perform the activities entail in the subject areas of morphology, phonology, grammar and usage, and mechanics and composition writing through teacher’s varied approaches, strategies, researches, and integration.

  4. Active Structural Fibers for Multifunctional Composite Materials (United States)


    Sebald [3] used extrusion methods to produce fibers with a platinum core surrounded by a PNN-PZT/ polymer binder which was fired to leave a platinum/PNN...researchers have developed composite piezoelectric devices consisting of an active piezoceramic fiber embedded in a polymer matrix. The polymer matrix fibers are embedded in a polymer matrix, the rule of mixtures can be applied again a second time by taking the piezoelectric shell to be an

  5. Structural Composites with Intrinsic Multifunctionality Project (United States)

    National Aeronautics and Space Administration — Development of multifunctional, structural materials for applications in terrestrial and space-based platforms is proposed. The principle innovation is the...

  6. Structural Composites with Intrinsic Multifunctionality Project (United States)

    National Aeronautics and Space Administration — Development of a multifunctional, structural material for applications in terrestrial and space-based platforms used for instrumentation in earth observation is...

  7. Self-healing sandwich composite structures (United States)

    Fugon, D.; Chen, C.; Peters, K.


    Previous research demonstrated that a thin self-healing layer is effective in recovering partial sandwich composite performance after an impact event. Many studies have been conducted that show the possibility of using Fiber Bragg Grating (FBG) sensors to monitor the cure of a resin through strain and temperature monitoring. For this experiment, FBG sensors were used to monitor the curing process of a self-healing layer within a twelve-layer fiberglass laminate after impact. First, five self-healing sandwich composite specimens were manufactured. FBG sensors were embedded between the fiberglass and foam core. Then the fiberglass laminate was impacted with the use of a drop tower and the curing process was monitored. The collected data was used to compare the cure of the resin and fiberglass alone to the cure of the resin from a self-healing specimen. For the low viscosity resin system tested, these changes were not sufficiently large to identify different polymerization states in the resin as it cured. These results indicate that applying different resin systems might increase the efficiency of the self-healing in the sandwich composites.

  8. Structural evolution of chitosan–palygorskite composites and removal of aqueous lead by composite beads

    Energy Technology Data Exchange (ETDEWEB)

    Rusmin, Ruhaida, E-mail: [CERAR – Centre for Environmental Risk Assessment and Remediation, Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); Faculty of Applied Sciences, Universiti Teknologi MARA Negeri Sembilan, Kuala Pilah 72000 (Malaysia); Sarkar, Binoy, E-mail: [CERAR – Centre for Environmental Risk Assessment and Remediation, Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); CRC CARE – Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, P.O. Box 486, Salisbury, SA 5106 (Australia); Liu, Yanju [CERAR – Centre for Environmental Risk Assessment and Remediation, Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); CRC CARE – Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, P.O. Box 486, Salisbury, SA 5106 (Australia); McClure, Stuart [CERAR – Centre for Environmental Risk Assessment and Remediation, Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); Naidu, Ravi, E-mail: [CERAR – Centre for Environmental Risk Assessment and Remediation, Building X, University of South Australia, Mawson Lakes, SA 5095 (Australia); CRC CARE – Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, P.O. Box 486, Salisbury, SA 5106 (Australia)


    Graphical abstract: - Highlights: • Facile preparation of chitosan–palygorskite composite beads demonstrated. • Components’ mass ratio impacted structural characteristics of composites. • Mechanism of composite formation and structure of composite beads proposed. • Composite beads adsorbed significantly greater amount of Pb than pristine materials. • In-depth investigation done on Pb adsorption mechanisms. - Abstract: This paper investigates the structural evolution of chitosan–palygorskite (CP) composites in relation to variable mass ratios of their individual components. The composite beads’ performance in lead (Pb) adsorption from aqueous solution was also examined. The composite beads were prepared through direct dispersion of chitosan and palygorskite at 1:1, 1:2 and 2:1 mass ratios (CP1, CP2 and C2P, respectively). Analyses by Fourier transform Infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller (BET) surface area, X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the dependence of the composites’ structural characteristics on their composition mass ratio. The chitosan–palygorskite composite beads exhibited a better Pb adsorption performance than the pristine materials (201.5, 154.5, 147.1, 27.7 and 9.3 mg g{sup −1} for CP1, C2P, CP2, chitosan and palygorskite, respectively). Adsorption of Pb by CP1 and CP2 followed Freundlich isothermal model, while C2P fitted to Langmuir model. Kinetic studies showed that adsorption by all the composites fitted to the pseudo-second order model with pore diffusion also acting as a major rate governing step. The surface properties and specific interaction between chitosan and palygorskite in the composites were the most critical factors that influenced their capabilities in removing toxic metals from water.

  9. Composite Sandwich Structures for Shock Mitigation and Energy Absorption (United States)


    June 29, 2016 Grant Title: Composite Sandwich Structures for Shock Mitigation and Energy Absorption Grant Number: NOOO 14-11-1-0485 Principal...NUMBER Composite Sandwich Structures for Shock Mitigation and Energy Absorption Sb. GRANT NUMBER N00014-11 -1-0485 Sc. PROGRAM ELEMENT NUMBER 6...foam cores offered greater blast resistance and energy absorption than the heavier and stronger foam cores. This was found to be the case even on an

  10. Fatigue Behavior of an Advanced SiC/SiC Composite at Elevated Temperature in Air and in Steam (United States)


    dispersion and failure modes in the final composite [3:460; 4:1]. The use of composite materials dates to ancient Egypt where straw reinforced the clay ...are divisible into two classes: traditional and advanced. Traditional ceramics are items such as bricks, pottery , or tiles. Advanced ceramics are

  11. Development of Zero Coefficient of Thermal Expansion composite tubes for stable space structures (United States)

    Strock, John D.


    Advanced composite materials are well suited for stable space structures due to their low Coefficient of Thermal Expansion (CTE), high stiffness and light weight. For a given design application, composite hardware can be tailored for strength, stiffness, CTE, and Coefficient of Moisture Expansion (CME). Computer modeling and laminate testing of high modulus graphite/epoxy tubes were evaluated for compressive strength, stiffness, CTE, CME and microcracking. Thermal cycling and microcracking effects on CTE were evaluated. Thin graphite/epoxy plies exhibited reduced microcracking. A zero CTE thin wall tube design resulted from the development program. Recent work on low moisture absorption resin systems is also discussed.

  12. CFRP composites for optics and structures in telescope applications (United States)

    Romeo, Robert C.


    The use of continuous fiber reinforced plastic, CFRP, composite materials is introduced here as a viable material for optical telescopes. The thermal characteristics of CFRPs make them attractive as dimensionally stable materials for all-composite telescope structures and mirrors. Composite mirrors have only recently shown promise as replacements for heavier and more fragile glass mirrors. The areal density of a CFRP mirror can be as much as 10 times less than that of a glass mirror. Optical test results show CFRP composite mirrors can be fabricated with an average surface roughness of less than 10 angstroms. Concept models of scope and CFRP optics with associated figure and roughness data are presented.


    Institute of Scientific and Technical Information of China (English)

    赵晓兵; 薛大为; 赵玉祥


    In selecting rational types of underground structures resisting explosion, in order to improve stress states of the structural section and make full use of material strength of each part of the section, the research method of composite structures is presented. Adopting the analysis method of micro-section free body, equilibrium equations, constraint equations and deformation coordination equations are given. Making use of the concept of generalized work and directly introducing Lagrange multiplier specific in physical meaning, the validity of the constructed generalized functional is proved by using variation method. The rational rigidity matching relationship of composite structure section is presented through example calculations.

  14. Composite chronicles: A study of the lessons learned in the development, production, and service of composite structures (United States)

    Vosteen, Louis F.; Hadcock, Richard N.


    A study of past composite aircraft structures programs was conducted to determine the lessons learned during the programs. The study focused on finding major underlying principles and practices that experience showed have significant effects on the development process and should be recognized and understood by those responsible for using of composites. Published information on programs was reviewed and interviews were conducted with personnel associated with current and past major development programs. In all, interviews were conducted with about 56 people representing 32 organizations. Most of the people interviewed have been involved in the engineering and manufacturing development of composites for the past 20 to 25 years. Although composites technology has made great advances over the past 30 years, the effective application of composites to aircraft is still a complex problem that requires experienced personnel with special knowledge. All disciplines involved in the development process must work together in real time to minimize risk and assure total product quality and performance at acceptable costs. The most successful programs have made effective use of integrated, collocated, concurrent engineering teams, and most often used well-planned, systematic development efforts wherein the design and manufacturing processes are validated in a step-by-step or 'building block' approach. Such approaches reduce program risk and are cost effective.

  15. Processing, structure and flexural strength of CNT and carbon fibre reinforced, epoxy-matrix hybrid composite

    Indian Academy of Sciences (India)

    K Chandra Shekar; M Sai Priya; P K Subramanian; Anil Kumar; B Anjaneya Prasad; N Eswara Prasad


    Advanced materials such as continuous fibre-reinforced polymer matrix composites offer significant enhancements in variety of properties, as compared to their bulk, monolithic counterparts. These properties include primarily the tensile stress, flexural stress and fracture parameters. However, till date, there are hardly any scientific studies reported on carbon fibre (Cf) and carbon nanotube (CNT) reinforced hybrid epoxy matrix composites (unidirectional). The present work is an attempt to bring out the flexural strength properties along with a detailed investigation in the synthesis of reinforced hybrid composite. In this present study, the importance of alignment of fibre is comprehensively evaluated and reported. The results obtained are discussed in terms of material characteristics, microstructure and mode of failure under flexural (3-point bend) loading. The study reveals the material exhibiting exceptionally high strength values and declaring itself as a material with high strength to weight ratio when compared to other competing polymer matrix composites (PMCs); as a novel structural material for aeronautical and aerospace applications.

  16. VARTM Process Modeling of Aerospace Composite Structures (United States)

    Song, Xiao-Lan; Grimsley, Brian W.; Hubert, Pascal; Cano, Roberto J.; Loos, Alfred C.


    A three-dimensional model was developed to simulate the VARTM composite manufacturing process. The model considers the two important mechanisms that occur during the process: resin flow, and compaction and relaxation of the preform. The model was used to simulate infiltration of a carbon preform with an epoxy resin by the VARTM process. The model predicted flow patterns and preform thickness changes agreed qualitatively with the measured values. However, the predicted total infiltration times were much longer than measured most likely due to the inaccurate preform permeability values used in the simulation.

  17. Blast Testing and Modelling of Composite Structures

    DEFF Research Database (Denmark)

    Giversen, Søren

    The motivation for this work is based on a desire for finding light weight alternatives to high strength steel as the material to use for armouring in military vehicles. With the use of high strength steel, an increase in the level of armouring has a significant impact on the vehicle weight......, affecting for example the manoeuvrability and top speed negatively, which ultimately affects the safety of the personal in the vehicle. Strong and light materials, such as fibre reinforced composites, could therefore act as substitutes for the high strength steel, and minimize the impact on the vehicle...

  18. Composite timber-concrete road bridge structure

    Directory of Open Access Journals (Sweden)

    Stojić Dragoslav


    Full Text Available This work presents preliminary design of the road bridge made of laminated timber. The supporting system of the main bearing elements is made of the laminated timber in the system of arch with three joints; the bridge slab is designed as continuous slab, made of nine equal fields; each pair is made as composite timber-concrete beam, where the road slab is made of concrete and the needle pieces are made of timber. Fundament is based on HW piles. All the elements are designed to Eurocode.

  19. Advances and trends in structures and dynamics; Proceedings of the Symposium, Washington, DC, October 22-25, 1984 (United States)

    Noor, A. K. (Editor); Hayduk, R. J. (Editor)


    Among the topics discussed are developments in structural engineering hardware and software, computation for fracture mechanics, trends in numerical analysis and parallel algorithms, mechanics of materials, advances in finite element methods, composite materials and structures, determinations of random motion and dynamic response, optimization theory, automotive tire modeling methods and contact problems, the damping and control of aircraft structures, and advanced structural applications. Specific topics covered include structural design expert systems, the evaluation of finite element system architectures, systolic arrays for finite element analyses, nonlinear finite element computations, hierarchical boundary elements, adaptive substructuring techniques in elastoplastic finite element analyses, automatic tracking of crack propagation, a theory of rate-dependent plasticity, the torsional stability of nonlinear eccentric structures, a computation method for fluid-structure interaction, the seismic analysis of three-dimensional soil-structure interaction, a stress analysis for a composite sandwich panel, toughness criterion identification for unidirectional composite laminates, the modeling of submerged cable dynamics, and damping synthesis for flexible spacecraft structures.

  20. Modeling of composite piezoelectric structures with the finite volume method. (United States)

    Bolborici, Valentin; Dawson, Francis P; Pugh, Mary C


    Piezoelectric devices, such as piezoelectric traveling- wave rotary ultrasonic motors, have composite piezoelectric structures. A composite piezoelectric structure consists of a combination of two or more bonded materials, at least one of which is a piezoelectric transducer. Piezoelectric structures have mainly been numerically modeled using the finite element method. An alternative approach based on the finite volume method offers the following advantages: 1) the ordinary differential equations resulting from the discretization process can be interpreted directly as corresponding circuits; and 2) phenomena occurring at boundaries can be treated exactly. This paper presents a method for implementing the boundary conditions between the bonded materials in composite piezoelectric structures modeled with the finite volume method. The paper concludes with a modeling example of a unimorph structure.

  1. Intrinsic manufacture of hollow thermoplastic composite/metal structures (United States)

    Barfuss, Daniel; Grützner, Raik; Garthaus, Christian; Gude, Maik; Müller, Roland; Langrebe, Dirk


    In contrast to common and classical joining technologies for composite/metal hybrid structures such as bonding and riveting, profile and contour joints offer a promising potential for novel lightweight hybrid structures. First and foremost, joining systems with a form closure function enable to pass very high loads into rod- and tube-shaped fibre reinforced structures and achieve high degrees of material utilization for the composite part. This paper demonstrates the theoretical and technological principals for a resource efficient design and production of highly loaded thermoplastic composite profile structures with integrated metallic load introduction elements and a multi scale form closure. The hybrid structures are produced in an integral blow moulding process in which a braided tape-preform is simultaneously consolidated and formed into the metallic load introduction element. These metallic load introduction elements are manufactured in a two-stage process of external and internal hydroforming, after forming simulations have assured process stability for consistent quality.

  2. Structural Abort Trigger for Ares Composites Project (United States)

    National Aeronautics and Space Administration — Structural health monitoring (SHM) methods have been limited for wide-area applications due to the implied infrastructure, including sensors, power/communication...

  3. Research Developments in Nondestructive Evaluation and Structural Health Monitoring for the Sustainment of Composite Aerospace Structures at NASA (United States)

    Cramer, K. Elliott


    The use of composite materials continues to increase in the aerospace community due to the potential benefits of reduced weight, increased strength, and manufacturability. Ongoing work at NASA involves the use of the large-scale composite structures for spacecraft (payload shrouds, cryotanks, crew modules, etc). NASA is also working to enable both the use and sustainment of composites in commercial aircraft structures. One key to the sustainment of these large composite structures is the rapid, in-situ characterization of a wide range of potential defects that may occur during the vehicle's life. Additionally, in many applications it is necessary to monitor changes in these materials over their lifetime. Quantitative characterization through Nondestructive Evaluation (NDE) of defects such as reduced bond strength, microcracking, and delamination damage due to impact, are of particular interest. This paper will present an overview of NASA's applications of NDE technologies being developed for the characterization and sustainment of advanced aerospace composites. The approaches presented include investigation of conventional, guided wave, and phase sensitive ultrasonic methods and infrared thermography techniques for NDE. Finally, the use of simulation tools for optimizing and validating these techniques will also be discussed.

  4. Subscale Development of Advanced ABM Graphite/Epoxy Composite Structure (United States)


    formulation. A statement on the prepreg certifi- cation as to the type resin employed is required. 4.10.3 Uncured Prepreg Tests Nonfiber...visible through the clear, moisture proof, plastic sealing bag: A-24 (1) Manufacturers name, symbol (2) Material type ; resin , resin/catalyst lot number

  5. High Temperature Advanced Structural Composites. Volume 3. Mechanics (United States)


    of Mechanics Associaqao Brasileira de CiUncias MecAnicas Hosted by Departamento de Engenharia Civil Pontiffcia Universidade Cat61ica do Rio de Janeiro...must conclude that regardless of their apparent popularity in the micromechanics literature, the self-consistent, Mori-Tanaka or other procedures

  6. CISM International Advanced School on Stability Problems of Steel Structures

    CERN Document Server

    Skaloud, M


    This volume strives to give complete information about the main aspect of the stability behaviour of steel structures and their members. In following this objective, the volume presents a complete scientific background (profiting from the fact that the authors of the individual parts of the publication have personally been very active in the corresponding field of research for an extended period of time now), but also establishes recommendations, procedures and formulae for practical design. The significance of the volume may be seen in its challenging current concepts of stability analysis, encouraging progress in the field and thereby establishing an advanced basis for more reliable and economical design.

  7. Computational modeling and impact analysis of textile composite structures (United States)

    Hur, Hae-Kyu

    This study is devoted to the development of an integrated numerical modeling enabling one to investigate the static and the dynamic behaviors and failures of 2-D textile composite as well as 3-D orthogonal woven composite structures weakened by cracks and subjected to static-, impact- and ballistic-type loads. As more complicated modeling about textile composite structures is introduced, some of homogenization schemes, geometrical modeling and crack propagations become more difficult problems to solve. To overcome these problems, this study presents effective mesh-generation schemes, homogenization modeling based on a repeating unit cell and sinusoidal functions, and also a cohesive element to study micro-crack shapes. This proposed research has two: (1) studying behavior of textile composites under static loads, (2) studying dynamic responses of these textile composite structures subjected to the transient/ballistic loading. In the first part, efficient homogenization schemes are suggested to show the influence of textile architectures on mechanical characteristics considering the micro modeling of repeating unit cell. Furthermore, the structures of multi-layered or multi-phase composites combined with different laminar such as a sub-laminate, are considered to find the mechanical characteristics. A simple progressive failure mechanism for the textile composites is also presented. In the second part, this study focuses on three main phenomena to solve the dynamic problems: micro-crack shapes, textile architectures and textile effective moduli. To obtain a good solutions of the dynamic problems, this research attempts to use four approaches: (I) determination of governing equations via a three-level hierarchy: micro-mechanical unit cell analysis, layer-wise analysis accounting for transverse strains and stresses, and structural analysis based on anisotropic plate layers, (II) development of an efficient computational approach enabling one to perform transient

  8. Structural Composites With Tuned EM Chirality (United States)


    ray -­‐ tracing   analysis.   A   composite  is  created  using  coils  of... MATLAB   code  directly  computes  the  group  velocity  and  pass  bands  for  a  given  set  of  wave  vectors   and...the  input  frequency  and  angle   of   incidence.    A   MATLAB  code  directly  computes   the  group

  9. High-Temperature Structures, Adhesives, and Advanced Thermal Protection Materials for Next-Generation Aeroshell Design (United States)

    Collins, Timothy J.; Congdon, William M.; Smeltzer, Stanley S.; Whitley, Karen S.


    The next generation of planetary exploration vehicles will rely heavily on robust aero-assist technologies, especially those that include aerocapture. This paper provides an overview of an ongoing development program, led by NASA Langley Research Center (LaRC) and aimed at introducing high-temperature structures, adhesives, and advanced thermal protection system (TPS) materials into the aeroshell design process. The purpose of this work is to demonstrate TPS materials that can withstand the higher heating rates of NASA's next generation planetary missions, and to validate high-temperature structures and adhesives that can reduce required TPS thickness and total aeroshell mass, thus allowing for larger science payloads. The effort described consists of parallel work in several advanced aeroshell technology areas. The areas of work include high-temperature adhesives, high-temperature composite materials, advanced ablator (TPS) materials, sub-scale demonstration test articles, and aeroshell modeling and analysis. The status of screening test results for a broad selection of available higher-temperature adhesives is presented. It appears that at least one (and perhaps a few) adhesives have working temperatures ranging from 315-400 C (600-750 F), and are suitable for TPS-to-structure bondline temperatures that are significantly above the traditional allowable of 250 C (482 F). The status of mechanical testing of advanced high-temperature composite materials is also summarized. To date, these tests indicate the potential for good material performance at temperatures of at least 600 F. Application of these materials and adhesives to aeroshell systems that incorporate advanced TPS materials may reduce aeroshell TPS mass by 15% - 30%. A brief outline is given of work scheduled for completion in 2006 that will include fabrication and testing of large panels and subscale aeroshell test articles at the Solar-Tower Test Facility located at Kirtland AFB and operated by Sandia

  10. Advanced Multifunctional Properties of Aligned Carbon Nanotube-Epoxy Composites from Carbon Nanotube Aerogel Method (United States)

    Tran, Thang; Liu, Peng; Fan, Zeng; Ngern, Nigel; Duong, Hai


    Unlike previous methods of making carbon nanotube (CNT) thin films, aligned CNT thin films in this work are synthesized directly from CNT aerogels in a CVD process. CH4/H2/He gases and ferrocene/thiophene catalysts are mixed and reacted in the reactor at 1200 °C to form CNT aerogel socks. By pulling out the socks with a metal rod, CNT thin films with 15-nm diameter MWNTs are aligned and produced continuously at a speed of a few meters per minute. The number of the aligned CNT thin film layers/ thickness can also be controlled well. The as-synthesized aligned CNT films are further condensed by acetone spray and post-treated by UV light. The aligned CNT films without any above post-treatment have a high electrical conductivity of 400S/cm. We also develop aligned CNT-epoxy composites by infiltrating epoxy into the above aligned CNT thin films using Vacuum Assisted Resin Transfer Molding (VARTM) method. Our cost-effective fabrication method of the aligned CNT films is more advanced for developing the composites having CNT orientation control. The mechanical, electrical and optical properties of the aligned CNT epoxy composites are measured. About 2% of the aligned CNTs can enhance significantly the electrical conductivity and hardness of aligned CNT-epoxy composite films. Effects of morphologies, volume fraction, and alignment of the CNTs on the advanced multifunctional properties of the aligned CNT-epoxy composites are also quantified.

  11. Blast and Impact Resistant Composite Structures for Navy Ships (United States)


    Journal of Composite Materials, 40: 1511-1575. 4. Schmidt, D., Shah , D. and Giannelis, E. P. (2002). New Advances in Polymer/Layered Silicate...Instruments: New Castle, DE, 2004. 10. Shah , V. Handbook of Plastics Testing Technology; Wiley: New York, 1984. 11. Khan, A. S.; Lopez-Pamies, O.; Kazmi...peak pressure testing in the subsequent 120 psi peak pressure testing. $$& VB . asmm 2? 20 -I IS 10 -Eß& -*-*xjterijaentiü pPurg^iuyl ester U

  12. Advanced structural design for precision radial velocity instruments (United States)

    Baldwin, Dan; Szentgyorgyi, Andrew; Barnes, Stuart; Bean, Jacob; Ben-Ami, Sagi; Brennan, Patricia; Budynkiewicz, Jamie; Chun, Moo-Young; Conroy, Charlie; Crane, Jeffrey D.; Epps, Harland; Evans, Ian; Evans, Janet; Foster, Jeff; Frebel, Anna; Gauron, Thomas; Guzman, Dani; Hare, Tyson; Jang, Bi-Ho; Jang, Jeong-Gyun; Jordan, Andres; Kim, Jihun; Kim, Kang-Min; Mendes de Oliveira, Claudia; Lopez-Morales, Mercedes; McCracken, Kenneth; McMuldroch, Stuart; Miller, Joseph; Mueller, Mark; Oh, Jae Sok; Ordway, Mark; Park, Byeong-Gon; Park, Chan; Park, Sung-Joon; Paxson, Charles; Phillips, David; Plummer, David; Podgorski, William; Seifahrt, Andreas; Stark, Daniel; Steiner, Joao; Uomoto, Alan; Walsworth, Ronald; Yu, Young-Sam


    The GMT-Consortium Large Earth Finder (G-CLEF) is an echelle spectrograph with precision radial velocity (PRV) capability that will be a first light instrument for the Giant Magellan Telescope (GMT). G-CLEF has a PRV precision goal of 40 cm/sec (10 cm/s for multiple measurements) to enable detection of Earth-like exoplanets in the habitable zones of sun-like stars1. This precision is a primary driver of G-CLEF's structural design. Extreme stability is necessary to minimize image motions at the CCD detectors. Minute changes in temperature, pressure, and acceleration environments cause structural deformations, inducing image motions which degrade PRV precision. The instrument's structural design will ensure that the PRV goal is achieved under the environments G-CLEF will be subjected to as installed on the GMT azimuth platform, including: Millikelvin (0.001 °K) thermal soaks and gradients 10 millibar changes in ambient pressure Changes in acceleration due to instrument tip/tilt and telescope slewing Carbon fiber/cyanate composite was selected for the optical bench structure in order to meet performance goals. Low coefficient of thermal expansion (CTE) and high stiffness-to-weight are key features of the composite optical bench design. Manufacturability and serviceability of the instrument are also drivers of the design. In this paper, we discuss analyses leading to technical choices made to minimize G-CLEF's sensitivity to changing environments. Finite element analysis (FEA) and image motion sensitivity studies were conducted to determine PRV performance under operational environments. We discuss the design of the optical bench structure to optimize stiffness-to-weight and minimize deformations due to inertial and pressure effects. We also discuss quasi-kinematic mounting of optical elements and assemblies, and optimization of these to ensure minimal image motion under thermal, pressure, and inertial loads expected during PRV observations.

  13. Displaying Composite and Archived Soundings in the Advanced Weather Interactive Processing System (United States)

    Barrett, Joe H., III; Volkmer, Matthew R.; Blottman, Peter F.; Sharp, David W.


    This presentation describes work done by the Applied Meteorology Unit (AMU) to add composite soundings to the Advanced Weather Interactive Processing System (AWIPS). This allows National Weather Service (NWS) forecasters to compare the current atmospheric state with climatology. In a previous task, the AMU created composite soundings for four rawinsonde observation stations in Florida, for each of eight flow regimes. The composite soundings were delivered to the NWS Melbourne (MLB) office for display using the NSHARP software program. NWS MLB requested that the AMU make the composite soundings available for display in AWIPS. The AMU first created a procedure to customize AWIPS so composite soundings could be displayed. A unique four-character identifier was created for each of the 32 composite soundings. The AMIU wrote a Tool Command Language/Tool Kit (TclITk) software program to convert the composite soundings from NSHARP to Network Common Data Form (NetCDF) format. The NetCDF files were then displayable by AWIPS.

  14. Ink composition for making a conductive silver structure (United States)

    Walker, Steven B.; Lewis, Jennifer A.


    An ink composition for making a conductive silver structure comprises a silver salt and a complex of (a) a complexing agent and a short chain carboxylic acid or (b) a complexing agent and a salt of a short chain carboxylic acid, according to one embodiment. A method for making a silver structure entails combining a silver salt and a complexing agent, and then adding a short chain carboxylic acid or a salt of the short chain carboxylic acid to the combined silver salt and a complexing agent to form an ink composition. A concentration of the complexing agent in the ink composition is reduced to form a concentrated formulation, and the silver salt is reduced to form a conductive silver structure, where the concentrated formulation and the conductive silver structure are formed at a temperature of about C. or less.

  15. Composition Structure of Interplanetary Coronal Mass Ejections From Multispacecraft Observations, Modeling, and Comparison with Numerical Simulations

    CERN Document Server

    Reinard, Alysha; Mulligan, Tamitha


    We present an analysis of the ionic composition of iron for two interplanetary coronal mass ejections observed in May 21-23 2007 by the ACE and STEREO spacecraft in the context of the magnetic structure of the ejecta flux rope, sheath region, and surrounding solar wind flow. This analysis is made possible due to recent advances in multispacecraft data interpolation, reconstruction, and visualization as well as results from recent modeling of ionic charge states in MHD simulations of magnetic breakout and flux cancellation CME initiation. We use these advances to interpret specific features of the ICME plasma composition resulting from the magnetic topology and evolution of the CME. We find that in both the data and our MHD simulations, the flux ropes centers are relatively cool, while charge state enhancements surround and trail the flux ropes. The magnetic orientation of the ICMEs are suggestive of magnetic breakout-like reconnection during the eruption process which could explain the spatial location of the...

  16. Advanced composite elevator for Boeing 727 aircraft. Volume 1: Technical summary (United States)

    Chovil, D. V.; Harvey, S. T.; Mccarty, J. E.; Desper, O. E.; Jamison, E. S.; Syder, H.


    The design, development, analysis, and testing activities and results that were required to produce five and one-half shipsets of advanced composite elevators for Boeing 727 aircraft are summarized. During the preliminary design period, alternative concepts were developed. After selection of the best design, detail design and basic configuration improvements were evaluated. Five and one-half shipsets were manufactured. All program goals (except competitive cost demonstration) were accomplished when our design met or exceeded all requirements, criteria, and objectives.

  17. High Thermal Conductivity NARloy-Z-Diamond Composite Combustion Chamber Liner For Advanced Rocket Engines (United States)

    Bhat, Biliyar N.; Ellis, David; Singh, Jogender


    Advanced high thermal conductivity materials research conducted at NASA Marshall Space Flight Center (MSFC) with state of the art combustion chamber liner material NARloy-Z showed that its thermal conductivity can be increased significantly by adding diamond particles and sintering it at high temperatures. For instance, NARloy-Z containing 40 vol. percent diamond particles, sintered at 975C to full density by using the Field assisted Sintering Technology (FAST) showed 69 percent higher thermal conductivity than baseline NARloy-Z. Furthermore, NARloy-Z-40vol. percent D is 30 percent lighter than NARloy-Z and hence the density normalized thermal conductivity is 140 percent better. These attributes will improve the performance and life of the advanced rocket engines significantly. By one estimate, increased thermal conductivity will directly translate into increased turbopump power up to 2X and increased chamber pressure for improved thrust and ISP, resulting in an expected 20 percent improvement in engine performance. Follow on research is now being conducted to demonstrate the benefits of this high thermal conductivity NARloy-Z-D composite for combustion chamber liner applications in advanced rocket engines. The work consists of a) Optimizing the chemistry and heat treatment for NARloy-Z-D composite, b) Developing design properties (thermal and mechanical) for the optimized NARloy-Z-D, c) Fabrication of net shape subscale combustion chamber liner, and d) Hot fire testing of the liner for performance. FAST is used for consolidating and sintering NARlo-Z-D. The subscale cylindrical liner with built in channels for coolant flow is also fabricated near net shape using the FAST process. The liner will be assembled into a test rig and hot fire tested in the MSFC test facility to determine performance. This paper describes the development of this novel high thermal conductivity NARloy-Z-D composite material, and the advanced net shape technology to fabricate the combustion

  18. Stress analysis of advanced attack helicopter composite main rotor blade root end lug (United States)

    Baker, D. J.


    Stress analysis of the Advanced Attack Helicopter (AAH) composite main rotor blade root end lug is described. The stress concentration factor determined from a finite element analysis is compared to an empirical value used in the lug design. The analysis and test data indicate that the stress concentration is primarily a function of configuration and independent of the range of material properties typical of Kevlar-49/epoxy and glass epoxy.

  19. Fiber optic system for the real time detection, localization, and classification of damage in composite aircraft structures (United States)

    Mendoza, Edgar; Prohaska, John; Kempen, Connie; Esterkin, Yan; Sun, Sunjian; Krishnaswamy, Sridhar


    Acoustic emission is the leading structural health monitoring technique use for the early warning detection of structural damage in advanced composite structures associated with impacts, cracks, fracture, and delaminations. This paper describes progress towards the development of a fiber optic acoustic emission sensor (FAESense™) system based on the use of a novel two-wave mixing interferometer produced on a photonic integrated circuit (PIC) microchip.

  20. Influence of particle structure on electrochemical character of composite graphite

    Institute of Scientific and Technical Information of China (English)


    The natural graphite has been used as the anode material for Lithium-Ion batteries, because of its low cost, chemical stability and excellent reversibility for Li+ insertion. However, the slow diffusion rate of lithium ion and poor compatibility with electrolyte solutions make it difficult to use in some conditions. In order to solve these problems, an epoxy-coke/graphite composite has been manufactured. The particle of composite carbonaceous material coated on non-graphitizable (hard) carbon matrix. Due to the disordered structure,the diffusion rate of lithium species in the non-graphitzable carbon is remarkably fast and less anisotropic. The process for preparing a composite carbon powder provides a promising new anode material with superior electrochemical properties for Li-ion batteries. The unique structure of epoxy-coke/graphite composite electrodes results in much better kinetics, also better recharge ability and initial charge/discharge efficiency.

  1. Structural and functional characterization of barium zirconium titanate / epoxy composites

    Directory of Open Access Journals (Sweden)

    Filiberto González Garcia


    Full Text Available The dielectric behavior of composite materials (barium zirconium titanate / epoxy system was analyzed as a function of ceramic concentration. Structure and morphologic behavior of the composites was investigated by X-ray Diffraction (XRD, Fourier transformed infrared spectroscopy (FT-IR, Raman spectroscopy, field emission scanning electron microscopy (FE-SEM and transmission electron microscopy (TEM analyses. Composites were prepared by mixing the components and pouring them into suitable moulds. It was demonstrated that the amount of inorganic phase affects the morphology of the presented composites. XRD revealed the presence of a single phase while Raman scattering confirmed structural transitions as a function of ceramic concentration. Changes in the ceramic concentration affected Raman modes and the distribution of particles along into in epoxy matrix. Dielectric permittivity and dielectric losses were influenced by filler concentration.

  2. Structural design of composite sealing systems for automotive applications

    Energy Technology Data Exchange (ETDEWEB)

    Tarnowski, T. [Dow Chemical Co., Southfield, MI (United States)


    New applications for composites in under-the-hood closure systems such as engine valve covers, transmission side covers, oil pans, and timing chain covers are developing rapidly. The primary driving forces are lighter weight of finished components, integrated designs, improved isolation of engine noise, improved materials systems, and matured manufacturing processes for composite materials. Thermoset-based composite materials, especially those based on high-temperature resistant epoxy vinylester matrices, offer improved elevated-temperature performance with respect to thermoplastic composites. This paper presents the current state-of-the-art design, engineering and optimization techniques for engine closure systems. The performance requirements of systems such as valve covers and oil pans are explained in detail. Techniques for long-term structural stiffness evaluation, vibration performance assessment and noise transmission estimation are described. The material characterization required to develop design allowables for long-term, high-temperature composite applications are also included.

  3. The evolution of composite materials in submarine structures.


    Lemiere, Y


    Since the sixties, the amount of composite structures on submarines has increased continuously. The main reasons are their low apparent weight in water, good behaviour in a marine environment, excellent mechanical properties and acoustic transparency. The new applications required the use of prepreg. Relevant processes had to be adapted to the large dimensions and thickness of the structures. Future applications will be concerned with both structures and internal equipment. A lively debate is...

  4. Structural Arrangement Trade Study. Volume 1: Reusable Hydrogen Composite Tank System (RHCTS) and Graphite Composite Primary Structures (GCPS). Executive summary (United States)


    This volume is the first of a three volume set that discusses the structural arrangement trade study plan that will identify the most suitable configuration for an SSTO winged vehicle capable of delivering 25,000 lbs to a 220 nm circular orbit at 51.6 deg inclination. The Reusable Hydrogen Composite Tank System (RHCTS), and Graphite Composite Primary Structures most suitable for intertank, wing and thrust structures are identified. This executive summary presents the trade study process, the selection process, requirements used, analysis performed and data generated. Conclusions and recommendations are also presented.

  5. Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Miao Yi [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Jiang, Xiaohong, E-mail: [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Piliptsou, D.G., E-mail: [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Zhuang, Yuzhao; Rogachev, A.V.; Rudenkov, A.S. [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Balmakou, A. [Faculty of Material Science and Technology, Slovak University of Technology, Trnava 91724 (Slovakia)


    Highlights: • Influence of the chromium interlayer on the structure and mechanical properties of a-C:Cr films. • Residual stress and wear of a-C:Cr and Cr/a-C varies due to their phase and surface morphology. • Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics. - Abstract: To improve structural, mechanical and chemical properties of diamond-like carbon films, we developed amorphous carbon chromium-modified composite films fabricated by means of cathode magnetic filtered arc deposition. The properties were analyzed by Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy for the purpose of the structure characterization, elemental analysis and topology examination. Moreover, we also assessed residual stress, the coefficient of friction, hardness, the elastic modulus and corrosion parameters through X-ray double-crystal surface profilometry, tribo-testing, nanoindenter-testing, as well as contact angle measurements and potentiodynamic polarization analysis. As a result of a comparative analysis, we revealed a substantial improvement in the characteristics of developed composite films in comparison with amorphous carbon films. For example, Cr-modification is resulted, in greater integrated performance, toughness and corrosion resistance; the residual stress was reduced substantially.

  6. Study of the costs and benefits of composite materials in advanced turbofan engines (United States)

    Steinhagen, C. A.; Stotler, C. L.; Neitzel, R. E.


    Composite component designs were developed for a number of applicable engine parts and functions. The cost and weight of each detail component was determined and its effect on the total engine cost to the aircraft manufacturer was ascertained. The economic benefits of engine or nacelle composite or eutectic turbine alloy substitutions was then calculated. Two time periods of engine certification were considered for this investigation, namely 1979 and 1985. Two methods of applying composites to these engines were employed. The first method just considered replacing an existing metal part with a composite part with no other change to the engine. The other method involved major engine redesign so that more efficient composite designs could be employed. Utilization of polymeric composites wherever payoffs were available indicated that a total improvement in Direct Operating Cost (DOC) of 2.82 to 4.64 percent, depending on the engine considered, could be attained. In addition, the percent fuel saving ranged from 1.91 to 3.53 percent. The advantages of using advanced materials in the turbine are more difficult to quantify but could go as high as an improvement in DOC of 2.33 percent and a fuel savings of 2.62 percent. Typically, based on a fleet of one hundred aircraft, a percent savings in DOC represents a savings of four million dollars per year and a percent of fuel savings equals 23,000 cu m (7,000,000 gallons) per year.

  7. Topologically ordered magnesium-biopolymer hybrid composite structures. (United States)

    Oosterbeek, Reece N; Seal, Christopher K; Staiger, Mark P; Hyland, Margaret M


    Magnesium and its alloys are intriguing as possible biodegradable biomaterials due to their unique combination of biodegradability and high specific mechanical properties. However, uncontrolled biodegradation of magnesium during implantation remains a major challenge in spite of the use of alloying and protective coatings. In this study, a hybrid composite structure of magnesium metal and a biopolymer was fabricated as an alternative approach to control the corrosion rate of magnesium. A multistep process that combines metal foam production and injection molding was developed to create a hybrid composite structure that is topologically ordered in all three dimensions. Preliminary investigations of the mechanical properties and corrosion behavior exhibited by the hybrid Mg-polymer composite structures suggest a new potential approach to the development of Mg-based biomedical devices.

  8. Well-formedness and typing rules for UML Composite Structures

    CERN Document Server

    Dragomir, Iulia


    Starting from version 2.0, UML introduced hierarchical composite structures, which are an expressive way of defining complex software architectures, but which have a very loosely defined semantics in the standard. In this paper we propose a set of consistency rules that disambiguate the meaning of UML composite structures. Our primary goal was to have an operational model of composite structures for the OMEGA UML profile, an executable profile dedicated to the formal specification and validation of real-time systems, developed in a past project to which we contributed. However, the rules and principles stated here are applicable to other hierarchical component models based on the same concepts, such as SysML. The presented ruleset is supported by an OCL formalization which is described in this report. This formalization was applied on different complex models for the evaluation and validation of the proposed principles.

  9. Use of lightweight composites for GAS payload structures (United States)

    Spencer, Mark B.


    A key element in the design of a small self-contained payload is the supporting structure. This structure must support the experiments and other components while using as little space and weight as possible. Hence, the structure material must have characteristics of being both strong and light. Aluminum was used for the structure on the first Purdue University payload, but consumed a relatively large percentage of the total payload weight. The current payload has a larger power supply requirement than did the previous payload. To allow additional weight for the batteries, a composite material has been chosen for the structure which has the required strength while being considerably lighter than aluminum. A radial fin design has been chosen for ease of composite material lay-up and its overall strength of design. A composite plate will connect the free ends of the fins and add strength and reduce vibration. The physical characteristics of the composite material and the method of open lay-up construction is described. Also discussed are the testing, modifications, and problems encountered during assembly of the experiments to the structure.

  10. Structure Change of the Insulating Composite

    Directory of Open Access Journals (Sweden)

    Vaclav Mentlik


    Full Text Available Modern power electric drives brought advantages in induction motor control. In the same time appeared problems with high frequency square waveform voltage (pulse stress produced by the voltage converters. Voltage converters produce repetitive pulses with high level of voltage rise fronts (slew rates. Rise fronts attained values of up to tens kilovolts per microsecond and voltage pulse repetition frequency up to some tens of kilohertz. This technology is an advantage for a drive control. Significant is the impact of these voltage waveforms on the motor insulations. Degradation of the main wall insulation can reduce the reliability of the electric motor and whole drive. In this paper is discussed one possible solution. The promising modification in the insulation material structure is presented in the paper.

  11. Design and analysis of composite structures with applications to aerospace structures

    CERN Document Server

    Kassapoglou, Christos


    Design and Analysis of Composite Structures enables graduate students and engineers to generate meaningful and robust designs of complex composite structures. Combining analysis and design methods for structural components, the book begins with simple topics such as skins and stiffeners and progresses through to entire components of fuselages and wings. Starting with basic mathematical derivation followed by simplifications used in real-world design, Design and Analysis of Composite Structures presents the level of accuracy and range of applicability of each method. Examples taken from ac

  12. In situ compositional control of advanced HgCdTe-based IR detectors (United States)

    Almeida, L. A.; Dinan, J. H.


    The application of a feedback control system for maintaining a desired compositional profile during Hg 1- xCd xTe epitaxy is reported. A spectroscopic ellipsometer monitored the optical properties of Hg 1- xCd xTe films during deposition by molecular beam epitaxy. A library of optical constants was established from in situ measurements of multiple layers of varying composition. The compositions were subsequently determined ex situ using Fourier transform infrared spectroscopy. This work represents an extension of the compositional range of this control system to measure the x-values of Hg 1- xCd xTe sensitive to long-, mid-, and short-wavelength infrared (LWIR, MWIR, and SWIR) radiation (0.16CdTe effusion cell. The application of this control system is demonstrated by measuring the compositional profile of a three layer Hg 1- xCd xTe structure suitable for use as an MWIR/SWIR detector.

  13. Reduced toxicity polyester resins and microvascular pre-preg tapes for advanced composites manufacturing (United States)

    Poillucci, Richard

    Advanced composites manufacturing broadly encapsulates topics ranging from matrix chemistries to automated machines that lay-up fiber-reinforced materials. Environmental regulations are stimulating research to reduce matrix resin formulation toxicity. At present, composites fabricated with polyester resins expose workers to the risk of contact with and inhalation of styrene monomer, which is a potential carcinogen, neurotoxin, and respiratory irritant. The first primary goal of this thesis is to reduce the toxicity associated with polyester resins by: (1) identification of potential monomers to replace styrene, (2) determination of monomer solubility within the polyester, and (3) investigation of approaches to rapidly screen a large resin composition parameter space. Monomers are identified based on their ability to react with polyester and their toxicity as determined by the Globally Harmonized System (GHS) and a green screen method. Solubilities were determined by the Hoftyzer -- Van Krevelen method, Hansen solubility parameter database, and experimental mixing of monomers. A combinatorial microfluidic mixing device is designed and tested to obtain distinct resin compositions from two input chemistries. The push for safer materials is complemented by a thrust for multifunctional composites. The second primary goal of this thesis is to design and implement the manufacture of sacrificial fiber materials suitable for use in automated fiber placement of microvascaular multifunctional composites. Two key advancements are required to achieve this goal: (1) development of a roll-to-roll method to place sacrificial fibers onto carbon fiber pre-preg tape; and (2) demonstration of feasible manufacture of microvascular carbon fiber plates with automated fiber placement. An automated method for placing sacrificial fibers onto carbon fiber tapes is designed and a prototype implemented. Carbon fiber tows with manual placement of sacrificial fibers is implemented within an

  14. Modelling of advanced structural materials for GEN IV reactors (United States)

    Samaras, M.; Hoffelner, W.; Victoria, M.


    The choice of suitable materials and the assessment of long-term materials damage are key issues that need to be addressed for the safe and reliable performance of nuclear power plants. Operating conditions such as high temperatures, irradiation and a corrosive environment degrade materials properties, posing the risk of very expensive or even catastrophic plant damage. Materials scientists are faced with the scientific challenge to determine the long-term damage evolution of materials under service exposure in advanced plants. A higher confidence in life-time assessments of these materials requires an understanding of the related physical phenomena on a range of scales from the microscopic level of single defect damage effects all the way up to macroscopic effects. To overcome lengthy and expensive trial-and-error experiments, the multiscale modelling of materials behaviour is a promising tool, bringing new insights into the fundamental understanding of basic mechanisms. This paper presents the multiscale modelling methodology which is taking root internationally to address the issues of advanced structural materials for Gen IV reactors.

  15. Composition-Structure-Property Relationships in Boroaluminosilicate Glasses

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Potuzak, M.; Mauro, J.C.


    The complicated structural speciation in boroaluminosilicate glasses leads to a mixed network former effect yielding nonlinear variation in many macroscopic properties as a function of chemical composition. Here we study the composition–structure–property relationships in a series of sodium...... boroaluminosilicate glasses from peralkaline to peraluminous compositions by substituting Al2O3 for SiO2. Our results reveal a pronounced change in all the measured physical properties (density, elastic moduli, hardness, glass transition temperature, and liquid fragility) around [Al2O3]–[Na2O]=0. The structural...

  16. Boreal Forests of Kamchatka: Structure and Composition

    Directory of Open Access Journals (Sweden)

    Markus P. Eichhorn


    Full Text Available Central Kamchatka abounds in virgin old-growth boreal forest, formed primarily by Larix cajanderi and Betula platyphylla in varying proportions. A series of eight 0.25–0.30 ha plots captured the range of forests present in this region and their structure is described. Overall trends in both uplands and lowlands are for higher sites to be dominated by L. cajanderi with an increasing component of B. platyphylla with decreasing altitude. The tree line on wet sites is commonly formed by mono-dominant B. ermanii forests. Basal area ranged from 7.8–38.1 m2/ha and average tree height from 8.3–24.7 m, both being greater in lowland forests. Size distributions varied considerably among plots, though they were consistently more even for L. cajanderi than B. platyphylla. Upland sites also contained a dense subcanopy of Pinus pumila averaging 38% of ground area. Soil characteristics differed among plots, with upland soils being of lower pH and containing more carbon. Comparisons are drawn with boreal forests elsewhere and the main current threats assessed. These forests provide a potential baseline to contrast with more disturbed regions elsewhere in the world and therefore may be used as a target for restoration efforts or to assess the effects of climate change independent of human impacts.

  17. Advances in biomimetic regeneration of elastic matrix structures. (United States)

    Sivaraman, Balakrishnan; Bashur, Chris A; Ramamurthi, Anand


    Elastin is a vital component of the extracellular matrix, providing soft connective tissues with the property of elastic recoil following deformation and regulating the cellular response via biomechanical transduction to maintain tissue homeostasis. The limited ability of most adult cells to synthesize elastin precursors and assemble them into mature crosslinked structures has hindered the development of functional tissue-engineered constructs that exhibit the structure and biomechanics of normal native elastic tissues in the body. In diseased tissues, the chronic overexpression of proteolytic enzymes can cause significant matrix degradation, to further limit the accumulation and quality (e.g., fiber formation) of newly deposited elastic matrix. This review provides an overview of the role and importance of elastin and elastic matrix in soft tissues, the challenges to elastic matrix generation in vitro and to regenerative elastic matrix repair in vivo, current biomolecular strategies to enhance elastin deposition and matrix assembly, and the need to concurrently inhibit proteolytic matrix disruption for improving the quantity and quality of elastogenesis. The review further presents biomaterial-based options using scaffolds and nanocarriers for spatio-temporal control over the presentation and release of these biomolecules, to enable biomimetic assembly of clinically relevant native elastic matrix-like superstructures. Finally, this review provides an overview of recent advances and prospects for the application of these strategies to regenerating tissue-type specific elastic matrix structures and superstructures.

  18. Analytical challenges of determining composition and structure in small volumes with applications to semiconductor technology, nanostructures and solid state science (United States)

    Ma, Zhiyong; Kuhn, Markus; Johnson, David C.


    Determining the structure and composition of small volumes is vital to the ability to understand and control nanoscale properties and critical for advancing both fundamental science and applications, such as semiconductor device manufacturing. While metrology of nanoscale materials (nanoparticles, nanocomposites) and nanoscale semiconductor structures is challenging, both basic research and cutting edge technology benefit from new and enhanced analytical techniques. This focus issue contains articles describing approaches to overcome the challenges in obtaining statistically significant atomic-scale quantification of structure and composition in a variety of materials and devices using electron microscopy and atom probe tomography.


    Energy Technology Data Exchange (ETDEWEB)



    OAK A271 COMPOSITION AND STRUCTURAL STUDIES OF STRONG GLOW DISCHARGE POLYMER COATINGS. An investigation of the chemical composition and structure of strong glow discharge (GDP) polymer shells made for cryogenic experiments at OMEGA is described. The investigation was carried out using combustion and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The strongest coatings were observed to have the lowest hydrogen content or hydrogen/carbon H/C ratio, whereas the weakest coatings had the highest hydrogen content or H/C ratio. Chemical composition results from combustion were used to complement FTIR analysis to determine the relative hydrogen content of as-fabricated coatings. Good agreement was observed between composition results obtained from combustion and FTIR analysis. FTIR analysis of coating structures showed the strongest coatings to have less terminal methyl groups and a more double bond or olefinic structure. Strong GDP coatings that were aged in air react more with oxygen and moisture than standard GDP coatings. In addition to a more olefinic structure, there may also be more free-radial sites present in strong GDP coatings, which leads to greater oxygen uptake.

  20. Microstructure, chemistry, and electronic structure of natural hybrid composites in abalone shell. (United States)

    Srot, Vesna; Wegst, Ulrike G K; Salzberger, Ute; Koch, Christoph T; Hahn, Kersten; Kopold, Peter; van Aken, Peter A


    The crystal structure and chemical composition at the inorganic/inorganic and inorganic/organic interfaces in abalone shell (genus Haliotis) were investigated using advanced analytical transmission electron microscopy (TEM) methods. Electron energy-loss near-edge structures (ELNES) of Ca-M2,3, C-K, Ca-L2,3, O-K and low-loss EEL spectra acquired from aragonite and calcite are distinctly different. When comparing biogenic with inorganic material for aragonite, only minor differences in C-K fine structures could be detected. The crystal structure of the mineral bridges was confirmed by ELNES experiments. ELNES and energy-filtered TEM (EFTEM) experiments of regular and self-healed interfaces between nacreous aragonite and prismatic calcite reveal relatively rough transitions. In this work, the importance of TEM specimen preparation and specimen damage on structural features is discussed.

  1. Carbon Nanotube Enhanced Aerospace Composite Materials A New Generation of Multifunctional Hybrid Structural Composites

    CERN Document Server

    Kostopoulos, V


    The well documented increase in the use of high performance composites as structural materials in aerospace components is continuously raising the demands in terms of dynamic performance, structural integrity, reliable life monitoring systems and adaptive actuating abilities. Current technologies address the above issues separately; material property tailoring and custom design practices aim to the enhancement of dynamic and damage tolerance characteristics, whereas life monitoring and actuation is performed with embedded sensors that may be detrimental to the structural integrity of the component. This publication explores the unique properties of carbon nanotubes (CNT) as an additive in the matrix of Fibre Reinforced Plastics (FRP), for producing structural composites with improved mechanical performance as well as sensing/actuating capabilities. The successful combination of the CNT properties and existing sensing actuating technologies leads to the realization of a multifunctional FRP structure. The curre...

  2. An Overview of Combustion Mechanisms and Flame Structures for Advanced Solid Propellants (United States)

    Beckstead, M. W.


    Ammonium perchlorate (AP) and cyclotretamethylenetetranitramine (HMX) are two solid ingredients often used in modern solid propellants. Although these two ingredients have very similar burning rates as monopropellants, they lead to significantly different characteristics when combined with binders to form propellants. Part of the purpose of this paper is to relate the observed combustion characteristics to the postulated flame structures and mechanisms for AP and HMX propellants that apparently lead to these similarities and differences. For AP composite, the primary diffusion flame is more energetic than the monopropellant flame, leading to an increase in burning rate over the monopropellant rate. In contrast the HMX primary diffusion flame is less energetic than the HMX monopropellant flame and ultimately leads to a propellant rate significantly less than the monopropellant rate in composite propellants. During the past decade the search for more energetic propellants and more environmentally acceptable propellants is leading to the development of propellants based on ingredients other than AP and HMX. The objective of this paper is to utilize the more familiar combustion characteristics of AP and HMX containing propellants to project the combustion characteristics of propellants made up of more advanced ingredients. The principal conclusion reached is that most advanced ingredients appear to burn by combustion mechanisms similar to HMX containing propellants rather than AP propellants.

  3. Net-Shape Tailored Fabrics For Complex Composite Structures (United States)

    Farley, Gary L.


    Proposed novel looms used to make fabric preforms for complex structural elements, both stiffening elements and skin, from continuous fiber-reinforced composite material. Components of looms include custom reed and differential fabric takeup system. Structural parts made best explained by reference to curved "I" cross-section frame. Technology not limited to these fiber orientations or geometry; fiber angles, frame radius of curvature, frame height, and flange width changed along length of structure. Weaving technology equally applicable to structural skins, such as wing of fuselage skins.

  4. Automated web service composition supporting conditional branch structures (United States)

    Wang, Pengwei; Ding, Zhijun; Jiang, Changjun; Zhou, Mengchu


    The creation of value-added services by automatic composition of existing ones is gaining a significant momentum as the potential silver bullet in service-oriented architecture. However, service composition faces two aspects of difficulties. First, users' needs present such characteristics as diversity, uncertainty and personalisation; second, the existing services run in a real-world environment that is highly complex and dynamically changing. These difficulties may cause the emergence of nondeterministic choices in the process of service composition, which has gone beyond what the existing automated service composition techniques can handle. According to most of the existing methods, the process model of composite service includes sequence constructs only. This article presents a method to introduce conditional branch structures into the process model of composite service when needed, in order to satisfy users' diverse and personalised needs and adapt to the dynamic changes of real-world environment. UML activity diagrams are used to represent dependencies in composite service. Two types of user preferences are considered in this article, which have been ignored by the previous work and a simple programming language style expression is adopted to describe them. Two different algorithms are presented to deal with different situations. A real-life case is provided to illustrate the proposed concepts and methods.

  5. Application of the self-diagnosis composite into concrete structure (United States)

    Matsubara, Hideaki; Shin, Soon-Gi; Okuhara, Yoshiki; Nomura, Hiroshi; Yanagida, Hiroaki


    The function and performance of the self-diagnosis composites embedded in mortar/concrete blocks and concrete piles were investigated by bending tests and electrical resistance measurements. Carbon powder (CP) and carbon fiber (CF) were introduced in glass fiber reinforced plastics composites to obtain electrical conductivity. The CP composite has commonly good performances in various bending tests of block and pile specimens, comparing to the CF composite. The electrical resistance of the CP composite increases in a small strain to response remarkably micro-crack formation at about 200 (mu) strain and to detect well to smaller deformations before the crack formation. The CP composite possesses a continuous resistance change up to a large strain level near the final fracture of concrete structures reinforced by steel bars. The cyclic bending tests showed that the micro crack closed at unloading state was able to be evaluated from the measurement of residual resistance. It has been concluded that the self- diagnosis composite is fairly useful for the measurement of damage and fracture in concrete blocks and piles.

  6. Studies on structural properties of clay magnesium ferrite nano composite

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Manpreet, E-mail:; Singh, Mandeep [Department of Chemistry, Punjab Agricultural University, Ludhiana-141004 (India); Jeet, Kiran, E-mail:; Kaur, Rajdeep [Electron Microscopy and Nanoscience Laboratory, Punjab Agricultural University, Ludhiana-141004 (India)


    Magnesium ferrite-bentonite clay composite was prepared by sol-gel combustion method employing citric acid as complexing agent and fuel. The effect of clay on the structural properties was studied with X-ray diffraction (XRD), Fourier transform infrared (FT-IR) Spectroscopy, Scanning electron microscopy (SEM), SEM- Energy dispersive Spectroscope (EDS) and BET surface area analyzer. Decrease in particle size and density was observed on addition of bentonite clay. The BET surface area of nano composite containing just 5 percent clay was 74.86 m{sup 2}/g. Whereas porosity increased from 40.5 per cent for the pure magnesium ferrite to 81.0 percent in the composite showing that nano-composite has potential application as an adsorbent.

  7. Structural Analysis of Novel Lignin-derived Carbon Composite Anodes

    Energy Technology Data Exchange (ETDEWEB)

    McNutt, Nicholas W [ORNL; Rios, Orlando [ORNL; Feygenson, Mikhail [ORNL; Proffen, Thomas E [ORNL; Keffer, David J [ORNL


    The development of novel lignin-based carbon composite anodes consisting of nanocrystalline and amorphous domains motivates the understanding of a relationship of the structural properties characterizing these materials, such as crystallite size, intracrystallite dspacing, crystalline volume fraction and composite density, with their pair distribution functions (PDF), obtained from both molecular dynamics simulation and neutron scattering. A model for these composite materials is developed as a function of experimentally measurable parameters and realized in fifteen composite systems, three of which directly match all parameters of their experimental counterparts. The accurate reproduction of the experimental PDFs using the model systems validates the model. The decomposition of the simulated PDFs provides an understanding of each feature in the PDF and allows for the development of a mapping between the defining characteristics of the PDF and the material properties of interest.

  8. Structure-Composition-Property Relationships in Polymeric Amorphous Calcium Phosphate-Based Dental Composites

    Directory of Open Access Journals (Sweden)

    Drago Skrtic


    Full Text Available Our studies of amorphous calcium phosphate (ACP-based materials over the last decade have yielded bioactive polymeric composites capable of protecting teeth from demineralization or even regenerating lost tooth mineral. The anti-cariogenic/remineralizing potential of these ACP composites originates from their propensity, when exposed to the oral environment, to release in a sustained manner sufficient levels of mineral-forming calcium and phosphate ions to promote formation of stable apatitic tooth mineral. However, the less than optimal ACP filler/resin matrix cohesion, excessive polymerization shrinkage and water sorption of these experimental materials can adversely affect their physicochemical and mechanical properties, and, ultimately, limit their lifespan. This study demonstrates the effects of chemical structure and composition of the methacrylate monomers used to form the matrix phase of composites on degree of vinyl conversion (DVC and water sorption of both copolymers and composites and the release of mineral ions from the composites. Modification of ACP surface via introducing cations and/or polymers ab initio during filler synthesis failed to yield mechanically improved composites. However, moderate improvement in composite’s mechanical stability without compromising its remineralization potential was achieved by silanization and/or milling of ACP filler. Using ethoxylated bisphenol A dimethacrylate or urethane dimethacrylate as base monomers and adding moderate amounts of hydrophilic 2-hydroxyethyl methacrylate or its isomer ethyl-α-hydroxymethacrylate appears to be a promising route to maximize the remineralizing ability of the filler while maintaining high DVC. Exploration of the structure/composition/property relationships of ACP fillers and polymer matrices is complex but essential for achieving a better understanding of the fundamental mechanisms that govern dissolution/re-precipitation of bioactive ACP fillers, and

  9. Novel 3D C-SiC Composites for Hot Structures Project (United States)

    National Aeronautics and Space Administration — Future NASA hypersonic vehicles offer a potential to incorporate advanced ceramic matrix composites (CMC). The key characteristics include excellent mechanical...

  10. Joining and Integration of Advanced Carbon-Carbon Composites to Metallic Systems for Thermal Management Applications (United States)

    Singh, M.; Asthana, R.


    Recent research and development activities in joining and integration of carbon-carbon (C/C) composites to metals such as Ti and Cu-clad-Mo for thermal management applications are presented with focus on advanced brazing techniques. A wide variety of carbon-carbon composites with CVI and resin-derived matrices were joined to Ti and Cu-clad Mo using a number of active braze alloys. The brazed joints revealed good interfacial bonding, preferential precipitation of active elements (e.g., Ti) at the composite/braze interface. Extensive braze penetration of the inter-fiber channels in the CVI C/C composites was observed. The chemical and thermomechanical compatibility between C/C and metals at elevated temperatures is assessed. The role of residual stresses and thermal conduction in brazed C/C joints is discussed. Theoretical predictions of the effective thermal resistance suggest that composite-to-metal brazed joints may be promising for lightweight thermal management applications.

  11. A critical review of nanotechnologies for composite aerospace structures (United States)

    Kostopoulos, Vassilis; Masouras, Athanasios; Baltopoulos, Athanasios; Vavouliotis, Antonios; Sotiriadis, George; Pambaguian, Laurent


    The past decade extensive efforts have been invested in understanding the nano-scale and revealing the capabilities offered by nanotechnology products to structural materials. Integration of nano-particles into fiber composites concludes to multi-scale reinforced composites and has opened a new wide range of multi-functional materials in industry. In this direction, a variety of carbon based nano-fillers has been proposed and employed, individually or in combination in hybrid forms, to approach the desired performance. Nevertheless, a major issue faced lately more seriously due to the interest of industry is on how to incorporate these nano-species into the final composite structure through existing manufacturing processes and infrastructure. This interest originates from several industrial applications needs that request the development of new multi-functional materials which combine enhanced mechanical, electrical and thermal properties. In this work, an attempt is performed to review the most representative processes and related performances reported in literature and the experience obtained on nano-enabling technologies of fiber composite materials. This review focuses on the two main composite manufacturing technologies used by the aerospace industry; Prepreg/Autoclave and Resin Transfer technologies. It addresses several approaches for nano-enabling of composites for these two routes and reports latest achieved results focusing on performance of nano-enabled fiber reinforced composites extracted from literature. Finally, this review work identifies the gap between available nano-technology integration routes and the established industrial composite manufacturing techniques and the challenges to increase the Technology Readiness Level to reach the demands for aerospace industry applications.

  12. Adhesive bonding of composite aircraft structures: Challenges and recent developments (United States)

    Pantelakis, Sp.; Tserpes, K. I.


    In this review paper, the challenges and some recent developments of adhesive bonding technology in composite aircraft structures are discussed. The durability of bonded joints is defined and presented for parameters that may influence bonding quality. Presented is also, a numerical design approach for composite joining profiles used to realize adhesive bonding. It is shown that environmental ageing and pre-bond contamination of bonding surfaces may degrade significantly fracture toughness of bonded joints. Moreover, it is obvious that additional research is needed in order to design joining profiles that will enable load transfer through shearing of the bondline. These findings, together with the limited capabilities of existing non-destructive testing techniques, can partially explain the confined use of adhesive bonding in primary composite aircraft structural parts.

  13. Structural characterization and lipid composition of acquired cholesteatoma

    DEFF Research Database (Denmark)

    Bloksgaard, Maria; Svane-Knudsen, Viggo; Sørensen, Jens A


    along a depth of more than 200 μm and resembles the stratum corneum of hyperorthokeratotic skin. Lipid compositional analyses of the cholesteatoma show the presence of all major lipid classes found in normal skin stratum corneum (ceramides, long chain fatty acids, and cholesterol). Consistent with this......HYPOTHESIS: The goal of this work is to characterize the morphology and lipid composition of acquired cholesteatoma. We hypothesize that constitutive lipid membranes are present in the cholesteatoma and resemble those found in human skin stratum corneum. METHODS: We performed a comparative...... noninvasive structural and lipid compositional study of acquired cholesteatoma and control human skin using multiphoton excitation fluorescence microscopy-related techniques and high-performance thin-layer chromatography. RESULTS: The structural arrangement of the cholesteatoma is morphologically invariant...

  14. Mechanical properties of Composite Engineering Structures by Multivolume Micromechanical Modelling

    Directory of Open Access Journals (Sweden)

    B. Novotný


    Full Text Available Engineering structures often consist of elements having the character of a periodically repeated composite structure. A multivolume micromechanical model based on a representative cell division into r1 × r2 × r3 subcells with different elastic material properties has been used in this paper to derive macromechanical characteristics of the composite construction response to applied load and temperature changes. The multivolume method is based on ensuring the equilibrium of the considered volume on an average basis. In the same (average way, the continuity conditions of displacements and tractions at the interfaces between subcells and between neighboring representative elements are imposed, resulting in a homogenization procedure that eliminates the discrete nature of the composite model. The details of the method are shown for the case of a concrete block pavement. A parametric study is presented illustrating the influence of joint thickness, joint filling material properties and the quality of bonding between block and filler elements.

  15. Characterization of the structure and composition of gecko adhesive setae


    Rizzo, N. W.; Gardner, K.H.; Walls, D.J; Keiper-Hrynko, N.M; Ganzke, T.S; Hallahan, D.L


    The ability of certain reptiles to adhere to vertical (and hang from horizontal) surfaces has been attributed to the presence of specialized adhesive setae on their feet. Structural and compositional studies of such adhesive setae will contribute significantly towards the design of biomimetic fibrillar adhesive materials. The results of electron microscopy analyses of the structure of such setae are presented, indicating their formation from aggregates of proteinaceous fibrils held together b...

  16. Better Finite-Element Analysis of Composite Shell Structures (United States)

    Clarke, Gregory


    A computer program implements a finite-element-based method of predicting the deformations of thin aerospace structures made of isotropic materials or anisotropic fiber-reinforced composite materials. The technique and corresponding software are applicable to thin shell structures in general and are particularly useful for analysis of thin beamlike members having open cross-sections (e.g. I-beams and C-channels) in which significant warping can occur.

  17. Advanced Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: NASA's Perspectives (United States)

    Zhu, Dongming


    This presentation reviews NASA environmental barrier coating (EBC) system development programs and the coating materials evolutions for protecting the SiC/SiC Ceramic Matrix Composites in order to meet the next generation engine performance requirements. The presentation focuses on several generations of NASA EBC systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. The current EBC development emphasis is placed on advanced NASA 2700F candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance are described. The research and development opportunities for advanced turbine airfoil environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling are discussed.

  18. Materials research at Stanford University. [composite materials, crystal structure, acoustics (United States)


    Research activity related to the science of materials is described. The following areas are included: elastic and thermal properties of composite materials, acoustic waves and devices, amorphous materials, crystal structure, synthesis of metal-metal bonds, interactions of solids with solutions, electrochemistry, fatigue damage, superconductivity and molecular physics and phase transition kinetics.

  19. Extended propagation model for interfacial crack in composite material structure

    Institute of Scientific and Technical Information of China (English)

    闫相桥; 冯希金


    An interfacial crack is a common damage in a composite material structure . An extended propaga-tion model has been established for an interfacial crack to study the dependence of crack growth on the relativesizes of energy release rates at left and right crack tips and the properties of interfacial material characterize thegrowth of interfacial crack better.

  20. Fracture toughness of advanced alumina ceramics and alumina matrix composites used for cutting tool edges

    Directory of Open Access Journals (Sweden)

    M. Szutkowska


    Full Text Available Purpose: Specific characteristics in fracture toughness measurements of advanced alumina ceramics and alumina matrix composites with particular reference to α-Al2O3, Al2O3-ZrO2, Al2O3-ZrO2-TiC and Al2O3-Ti(C,N has been presented.Design/methodology/approach: The present study reports fracture toughness obtained by means of the conventional method and direct measurements of the Vickers crack length (DCM method of selected tool ceramics based on alumina: pure alumina, alumina-zirconia composite with unstabilized and stabilized zirconia, alumina–zirconia composite with addition of TiC and alumina–nitride-carbide titanium composite with 2wt% of zirconia. Specimens were prepared from submicro-scale trade powders. Vicker’s hardness (HV1, fracture toughness (KIC at room temperature, the indentation fracture toughness, Young’s modulus and apparent density were also evaluated. The microstructure was observed by means of scanning electron microscopy (SEM.Findings: The lowest value of KIC is revealed by pure alumina ceramics. The addition of (10 wt% unstabilized zirconia to alumina or a small amount (5 wt% of TiC to alumina–zirconia composite improve fracture toughness of these ceramics in comparison to alumina ceramics. Alumina ceramics and alumina-zirconia ceramics reveal the pronounced character of R-curve because of an increasing dependence on crack growth resistance with crack extension as opposed to the titanium carbide-nitride reinforced composite based on alumina. R-curve has not been observed for this composite.Practical implications: The results show the method of fracture toughness improvement of alumina tool ceramics.Originality/value: Taking into account the values of fracture toughness a rational use of existing ceramic tools should be expected.

  1. Light Water Reactor Sustainability Program Advanced Seismic Soil Structure Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Bolisetti, Chandrakanth [Idaho National Lab. (INL), Idaho Falls, ID (United States); Coleman, Justin Leigh [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    Risk calculations should focus on providing best estimate results, and associated insights, for evaluation and decision-making. Specifically, seismic probabilistic risk assessments (SPRAs) are intended to provide best estimates of the various combinations of structural and equipment failures that can lead to a seismic induced core damage event. However, in some instances the current SPRA approach has large uncertainties, and potentially masks other important events (for instance, it was not the seismic motions that caused the Fukushima core melt events, but the tsunami ingress into the facility). SPRA’s are performed by convolving the seismic hazard (this is the estimate of all likely damaging earthquakes at the site of interest) with the seismic fragility (the conditional probability of failure of a structure, system, or component given the occurrence of earthquake ground motion). In this calculation, there are three main pieces to seismic risk quantification, 1) seismic hazard and nuclear power plants (NPPs) response to the hazard, 2) fragility or capacity of structures, systems and components (SSC), and 3) systems analysis. Two areas where NLSSI effects may be important in SPRA calculations are, 1) when calculating in-structure response at the area of interest, and 2) calculation of seismic fragilities (current fragility calculations assume a lognormal distribution for probability of failure of components). Some important effects when using NLSSI in the SPRA calculation process include, 1) gapping and sliding, 2) inclined seismic waves coupled with gapping and sliding of foundations atop soil, 3) inclined seismic waves coupled with gapping and sliding of deeply embedded structures, 4) soil dilatancy, 5) soil liquefaction, 6) surface waves, 7) buoyancy, 8) concrete cracking and 9) seismic isolation The focus of the research task presented here-in is on implementation of NLSSI into the SPRA calculation process when calculating in-structure response at the area

  2. Super-hybrid composites - An emerging structural material (United States)

    Chamis, C. C.; Lark, R. F.; Sullivan, T. L.


    Specimens of super-hybrids and advanced fiber composites were subjected to extensive tests to determine their mechanical properties, including impact and thermal fatigue. The super-hybrids were fabricated by a procedure similar to that reported by Chamis et al., (1975). Super-hybrids subjected to 1000 cycles of thermal fatigue from -100 to 300 F retained over 90% of their longitudinal flexural strength and over 75% of their transverse flexural strength; their transverse flexural strength may be as high as 8 times that of a commercially supplied boron/1100-Al composite. The thin specimen Izod longitudinal impact resistance of the super-hybrids was twice that of the boron/110-Al material. Super-hybrids subjected to transverse tensile loads exhibited nonlinear stress-strain relationships. The experimentally determined initial membrane (in-plane) and bending elastic properties of super-hybrids were predicted adequately by linear laminate analysis.

  3. Smart Manufacture Process and Structure for Composite Materials

    Institute of Scientific and Technical Information of China (English)


    It is difficult to ensure the manufacturing process of composites for the reason that there are complicated processes during curing process of composites. The cure cycle has a significant effect on the quality of the finished part. The traditional cure cycle based on empirical approach could not ensure the quality of cured products because of unstabilized performance, high cost of production and low efficiency. As complex intelligent manufacturing systems are developed increasingly in industry, the necessity of more userfriendly operation system is becoming progressively importance for their utilization and market value. This paper introduces some of the recent technological advances in the intelligent manufacturing systems that will influence the design and development of relevant industry.

  4. Innovative Structural Materials and Sections with Strain Hardening Cementitious Composites (United States)

    Dey, Vikram

    The motivation of this work is based on development of new construction products with strain hardening cementitious composites (SHCC) geared towards sustainable residential applications. The proposed research has three main objectives: automation of existing manufacturing systems for SHCC laminates; multi-level characterization of mechanical properties of fiber, matrix, interface and composites phases using servo-hydraulic and digital image correlation techniques. Structural behavior of these systems were predicted using ductility based design procedures using classical laminate theory and structural mechanics. SHCC sections are made up of thin sections of matrix with Portland cement based binder and fine aggregates impregnating continuous one-dimensional fibers in individual or bundle form or two/three dimensional woven, bonded or knitted textiles. Traditional fiber reinforced concrete (FRC) use random dispersed chopped fibers in the matrix at a low volume fractions, typically 1-2% to avoid to avoid fiber agglomeration and balling. In conventional FRC, fracture localization occurs immediately after the first crack, resulting in only minor improvement in toughness and tensile strength. However in SHCC systems, distribution of cracking throughout the specimen is facilitated by the fiber bridging mechanism. Influence of material properties of yarn, composition, geometry and weave patterns of textile in the behavior of laminated SHCC skin composites were investigated. Contribution of the cementitious matrix in the early age and long-term performance of laminated composites was studied with supplementary cementitious materials such as fly ash, silica fume, and wollastonite. A closed form model with classical laminate theory and ply discount method, coupled with a damage evolution model was utilized to simulate the non-linear tensile response of these composite materials. A constitutive material model developed earlier in the group was utilized to characterize and

  5. Erosion Coatings for High-Temperature Polymer Composites: A Collaborative Project With Allison Advanced Development Company (United States)

    Sutter, James K.


    The advantages of replacing metals in aircraft turbine engines with high-temperature polymer matrix composites (PMC's) include weight savings accompanied by strength improvements, reduced part count, and lower manufacturing costs. Successfully integrating high-temperature PMC's into turbine engines requires several long-term characteristics. Resistance to surface erosion is one rarely reported property of PMC's in engine applications because PMC's are generally softer than metals and their erosion resistance suffers. Airflow rates in stationary turbine engine components typically exceed 2.3 kg/sec at elevated temperatures and pressures. In engine applications, as shown in the following photos, the survivability of PMC components is clearly a concern, especially when engine and component life-cycle requirements become longer. Although very few publications regarding the performance of erosion coatings on PMC's are available particularly in high-temperature applications the use of erosion-resistant coatings to significantly reduce wear on metallic substrates is well documented. In this study initiated by the NASA Glenn Research Center at Lewis Field, a low-cost (less than $140/kg) graphite-fiber-reinforced T650 35/PMR 15 sheet-molding compound was investigated with various coatings. This sheet-molding compound has been compression molded into many structurally complicated components, such as shrouds for gas turbine inlet housings and gearboxes. Erosion coatings developed for PMC s in this study consisted of a two-layered system: a bondcoat sprayed onto a cleaned PMC surface, followed by an erosion-resistant, hard topcoat sprayed onto the bondcoat as shown in following photomicrograph. Six erosion coating systems were evaluated for their ability to withstand harsh thermal cycles, erosion resistance (ASTM G76 83 "Standard Practice for Conducting Erosion Tests by Solid Particle Impingement Using Gas Jets") using Al2O3, and adhesion to the graphite fiber polyimide

  6. A Study of Flexible Composites for Expandable Space Structures (United States)

    Scotti, Stephen J.


    Payload volume for launch vehicles is a critical constraint that impacts spacecraft design. Deployment mechanisms, such as those used for solar arrays and antennas, are approaches that have successfully accommodated this constraint, however, providing pressurized volumes that can be packaged compactly at launch and expanded in space is still a challenge. One approach that has been under development for many years is to utilize softgoods - woven fabric for straps, cloth, and with appropriate coatings, bladders - to provide this expandable pressure vessel capability. The mechanics of woven structure is complicated by a response that is nonlinear and often nonrepeatable due to the discrete nature of the woven fiber architecture. This complexity reduces engineering confidence to reliably design and certify these structures, which increases costs due to increased requirements for system testing. The present study explores flexible composite materials systems as an alternative to the heritage softgoods approach. Materials were obtained from vendors who utilize flexible composites for non-aerospace products to determine some initial physical and mechanical properties of the materials. Uniaxial mechanical testing was performed to obtain the stress-strain response of the flexible composites and the failure behavior. A failure criterion was developed from the data, and a space habitat application was used to provide an estimate of the relative performance of flexible composites compared to the heritage softgoods approach. Initial results are promising with a 25% mass savings estimated for the flexible composite solution.

  7. Natural Kenaf Fiber Reinforced Composites as Engineered Structural Materials (United States)

    Dittenber, David B.

    The objective of this work was to provide a comprehensive evaluation of natural fiber reinforced polymer (NFRP)'s ability to act as a structural material. As a chemical treatment, aligned kenaf fibers were treated with sodium hydroxide (alkalization) in different concentrations and durations and then manufactured into kenaf fiber / vinyl ester composite plates. Single fiber tensile properties and composite flexural properties, both in dry and saturated environments, were assessed. Based on ASTM standard testing, a comparison of flexural, tensile, compressive, and shear mechanical properties was also made between an untreated kenaf fiber reinforced composite, a chemically treated kenaf fiber reinforced composite, a glass fiber reinforced composite, and oriented strand board (OSB). The mechanical properties were evaluated for dry samples, samples immersed in water for 50 hours, and samples immersed in water until saturation (~2700 hours). Since NFRPs are more vulnerable to environmental effects than synthetic fiber composites, a series of weathering and environmental tests were conducted on the kenaf fiber composites. The environmental conditions studied include real-time outdoor weathering, elevated temperatures, immersion in different pH solutions, and UV exposure. In all of these tests, degradation was found to be more pronounced in the NFRPs than in the glass FRPs; however, in nearly every case the degradation was less than 50% of the flexural strength or stiffness. Using a method of overlapping and meshing discontinuous fiber ends, large mats of fiber bundles were manufactured into composite facesheets for structural insulated panels (SIPs). The polyisocyanurate foam cores proved to be poorly matched to the strength and stiffness of the NFRP facesheets, leading to premature core shear or delamination failures in both flexure and compressive testing. The NFRPs were found to match well with the theoretical stiffness prediction methods of classical lamination

  8. Structure of metal matrix composites with an addition of tuff

    Directory of Open Access Journals (Sweden)

    M. Łach


    Full Text Available The article presents preliminary results of tests of metal matrix composites structure which was modified by an addition of powderedvolcanic tuff. Distribution and shape of ceramic particles as well as the quality of the bonding along the tuff- metal matrix interface werestudied. Depth of tuff element diffusion in the matrix as well as diffusion in tuff particles were checked. Micro-hardness and porosity of the composites were also tested. The tuff from Filipowice near the town of Krzeszowice was used for the tests. Powder metallurgy wasapplied to obtain the composites and the matrix materials were copper and 316L steel powders. The tuff was introduced in 2, 5 and 10 %by weight. To remove water from the channels of aluminosilicates, the tuff was baked at 850 oC for 4 hours and then cooled together withthe oven. The tests revealed good quality of the bonding of the tuff particles and the matrix and their even distribution. The addition of tuff improved the hardness of the composites and reduced their porosity which has great significance because of possible applications of this kind of materials in general and copper composites in particular. This gives grounds for further studies on volcanic tuff use in metal composites

  9. Hybrid Composites for LH2 Fuel Tank Structure (United States)

    Grimsley, Brian W.; Cano, Roberto J.; Johnston, Norman J.; Loos, Alfred C.; McMahon, William M.


    The application of lightweight carbon fiber reinforced plastics (CFRP) as structure for cryogenic fuel tanks is critical to the success of the next generation of Reusable Launch Vehicles (RLV). The recent failure of the X-33 composite fuel tank occurred in part due to microcracking of the polymer matrix, which allowed cryogen to permeate through the inner skin to the honeycomb core. As part of an approach to solve these problems, NASA Langley Research Center (LaRC) and Marshall Space Flight Center (MSFC) are working to develop and investigate polymer films that will act as a barrier to the permeation of LH2 through the composite laminate. In this study two commercially available films and eleven novel LaRC films were tested in an existing cryogenics laboratory at MSFC to determine the permeance of argon at room temperature. Several of these films were introduced as a layer in the composite to form an interleaved, or hybrid, composite to determine the effects on permeability. In addition, the effects of the interleaved layer thickness, number, and location on the mechanical properties of the composite laminate were investigated. In this initial screening process, several of the films were found to exhibit lower permeability to argon than the composite panels tested.

  10. Composites for Cryotank Structures. Present and Future: MSFC Perspective (United States)

    Vaughn, Timothy P.


    The development of reusable launch vehicle systems for a single stage to orbit vehicle requires vehicles at liftoff with 85% to 94% of its mass consisting exclusively of propellants. These dry mass requirements drive designs to utilize stronger, lighter weight materials for structures. This technology development focus has allowed the introduction of composite materials in lieu of conventional metallic materials due to their higher specific strengths. Composite materials were successfully used for the liquid hydrogen tanks for the DC-XA, and a multi-lobed liquid hydrogen tank will be employed for the X-33. Another potential non-traditional application for composite materials is for liquid oxygen tanks, which is still being investigated. Traditionally, organic materials have been avoided wherever possible, due the potential fire hazard and the fact that composites fail conventional oxygen compatibility requirements. However, the potential weight savings warrant the investigation of the use of polymeric composite materials in oxygen environments. Since composites fail the conventional, time-proven test methods because they are considered flammable by test, we have embarked on an innovative approach to oxygen compatibility testing and evaluation focused on the use environments and attempts to eliminate or "design away" all potential ignition sources. Oxygen compatibility is defined as the ability of a material to coexist with oxygen and potential ignition sources with an acceptable, manageable degree of risk.

  11. Local structure, composition, and crystallization mechanism of a model two-phase "composite nanoglass" (United States)

    Chattopadhyay, Soma; Kelly, S. D.; Shibata, Tomohiro; Balasubramanian, M.; Srinivasan, S. G.; Du, Jincheng; Banerjee, Rajarshi; Ayyub, Pushan


    We report a detailed study of the local composition and structure of a model, bi-phasic nanoglass with nominal stoichiometry Cu55Nb45. Three dimensional atom probe data suggest a nanoscale-phase-separated glassy structure having well defined Cu-rich and Nb-rich regions with a characteristic length scale of ≈3 nm. However, extended x-ray absorption fine structure analysis indicates subtle differences in the local environments of Cu and Nb. While the Cu atoms displayed a strong tendency to cluster and negligible structural order beyond the first coordination shell, the Nb atoms had a larger fraction of unlike neighbors (higher chemical order) and a distinctly better-ordered structural environment (higher topological order). This provides the first experimental indication that metallic glass formation may occur due to frustration arising from the competition between chemical ordering and clustering. These observations are complemented by classical as well as ab initio molecular dynamics simulations. Our study indicates that these nanoscale phase-separated glasses are quite distinct from the single phase nanoglasses (studied by Gleiter and others) in the following three respects: (i) they contain at least two structurally and compositionally distinct, nanodispersed, glassy phases, (ii) these phases are separated by comparatively sharp inter-phase boundaries, and (iii) thermally induced crystallization occurs via a complex, multi-step mechanism. Such materials, therefore, appear to constitute a new class of disordered systems that may be called a composite nanoglass.

  12. Local structure, composition, and crystallization mechanism of a model two-phase “composite nanoglass”

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, Soma; Shibata, Tomohiro [CSRRI-IIT, MRCAT, Sector 10, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kelly, S. D. [EXAFS Analysis, Bolingbrook, Illinois 60440 (United States); Balasubramanian, M. [Sector 20 XOR, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Srinivasan, S. G.; Du, Jincheng; Banerjee, Rajarshi [Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76203-5017 (United States); Ayyub, Pushan, E-mail: [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005 (India)


    We report a detailed study of the local composition and structure of a model, bi-phasic nanoglass with nominal stoichiometry Cu{sub 55}Nb{sub 45}. Three dimensional atom probe data suggest a nanoscale-phase-separated glassy structure having well defined Cu-rich and Nb-rich regions with a characteristic length scale of ≈3 nm. However, extended x-ray absorption fine structure analysis indicates subtle differences in the local environments of Cu and Nb. While the Cu atoms displayed a strong tendency to cluster and negligible structural order beyond the first coordination shell, the Nb atoms had a larger fraction of unlike neighbors (higher chemical order) and a distinctly better-ordered structural environment (higher topological order). This provides the first experimental indication that metallic glass formation may occur due to frustration arising from the competition between chemical ordering and clustering. These observations are complemented by classical as well as ab initio molecular dynamics simulations. Our study indicates that these nanoscale phase-separated glasses are quite distinct from the single phase nanoglasses (studied by Gleiter and others) in the following three respects: (i) they contain at least two structurally and compositionally distinct, nanodispersed, glassy phases, (ii) these phases are separated by comparatively sharp inter-phase boundaries, and (iii) thermally induced crystallization occurs via a complex, multi-step mechanism. Such materials, therefore, appear to constitute a new class of disordered systems that may be called a composite nanoglass.

  13. Structural efficiency study of composite wing rib structures (United States)

    Swanson, Gary D.; Gurdal, Zafer; Starnes, James H., Jr.


    A series of short stiffened panel designs which may be applied to a preliminary design assessment of an aircraft wing rib is presented. The computer program PASCO is used as the primary design and analysis tool to assess the structural efficiency and geometry of a tailored corrugated panel, a corrugated panel with a continuous laminate, a hat stiffened panel, a blade stiffened panel, and an unstiffened flat plate. To correct some of the shortcomings in the PASCO analysis when shear is present, a two step iterative process using the computer program VICON is used. The loadings considered include combinations of axial compression, shear, and lateral pressure. The loading ranges considered are broad enough such that the designs presented may be applied to other stiffened panel applications. An assessment is made of laminate variations, increased spacing, and nonoptimum geometric variations, including a beaded panel, on the design of the panels.

  14. Post-Buckling, Damage Tolerance and Manufacturing Techniques for Advanced Composite Materials. (United States)


    ADVAN. J DUGUNDJI ET AL. UNCLASSIFIED AuG 96 TELA-96-23 RMRIL-TR-87-4006 F/G 11/4 MI L2.5 11111 . L6 5 8Wo1 ~E 13.2 12 LooI 1111 1111.4 11.6...MANUFACTURING TECHNIQUES FOR ADVANCED COMPOSITE MATERIALS 00 NN John Dugundji , Paul A. Lagace, James W. Mar, Theodore H.H. Pian CO Massachusetts Institute...describing the experimental results and correlations is in preparation: Wang, Pian, Dugundji and Lagace [5]. 8 - N ~N - - --~ 4 - :)AMAGE. T111H - FPIRURJD

  15. Recent advancements in the electromechanical (E/M) impedance method for structural health monitoring and NDE (United States)

    Giurgiutiu, Victor; Rogers, Craig A.


    The emerging electro-mechanical impedance technology has high potential for in-situ health monitoring and NDE of structural systems and complex machinery. At first, the fundamental principles of the electro-mechanical impedance method are briefly reviewed and ways for practical implementation are highlighted. The equations of piezo- electric material response are given, and the coupled electro-mechanical impedance of a piezo-electric wafer transducer as affixed to the monitored structure is discussed. Due to the high frequency operation of this NDE method, wave propagation phenomena are identified as the primary coupling method between the structural substrate and the piezo-electric wafer transducer. Attention is then focused on several recent advancements that have extended the electro-mechanical impedance method into new areas of applications and/or have developed its underlying principles. US Army Construction Engineering Research Laboratory used the electro-mechanical impedance method to monitor damage development in composite overlaid civil infrastructure specimens under full-scale static testing. A simplified E/M impedance measuring technique was employed at the Polytechnic University of Madrid, Spain, to detect damage in GFRP composite specimens. The development of miniaturized `bare-bones' impedance analyzer equipment that could be easily packaged into transponder-size dimensions is being studied at the University of South Carolina. US Army Research Laboratory developed novel piezo-composite film transducers for embedment into composite structures. Disbond gauges for monitoring the structural joints of adhesively bonded rotor blades have been studies in the Mechanical Engineering Department at the University of South Carolina. These recent developments accentuate the importance and benefits of using the electro-mechanical impedance method for on-line health monitoring and damage detection in a variety of applications. Further investigation of the electro

  16. Advanced new lightweight materials: Hollow-sphere composites (HSCs) for mechanical engineering applications

    Energy Technology Data Exchange (ETDEWEB)

    Baumeister, E.; Klaeger, S. [Otto-von-Guerike-Universitaet, IFQ, Postfach 4120, D-39016 Magdeburg (Germany)


    ''Lightweight'' is a major trend in machine tool design to ensure higher speed and higher acceleration of elements, which results from state-of-the-art technology, such as the new linear drive and the control system.{sup [1]} Research is being carried out in institutes worldwide into lightweight construction by either design and/or choice of material. One type of advanced lightweight engineering material to reduce the mass of the moving parts of machine tools is hollow-sphere composites. Investigations of their thermal and mechanical properties show the superior quality of HSCs compared with alternative materials. Example applications of hollow-sphere composites include the table of a milling machine and robot arms. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  17. Structural level characterization of base oils using advanced analytical techniques

    KAUST Repository

    Hourani, Nadim


    Base oils, blended for finished lubricant formulations, are classified by the American Petroleum Institute into five groups, viz., groups I-V. Groups I-III consist of petroleum based hydrocarbons whereas groups IV and V are made of synthetic polymers. In the present study, five base oil samples belonging to groups I and III were extensively characterized using high performance liquid chromatography (HPLC), comprehensive two-dimensional gas chromatography (GC×GC), and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) equipped with atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) sources. First, the capabilities and limitations of each analytical technique were evaluated, and then the availed information was combined to reveal compositional details on the base oil samples studied. HPLC showed the overwhelming presence of saturated over aromatic compounds in all five base oils. A similar trend was further corroborated using GC×GC, which yielded semiquantitative information on the compound classes present in the samples and provided further details on the carbon number distributions within these classes. In addition to chromatography methods, FT-ICR MS supplemented the compositional information on the base oil samples by resolving the aromatics compounds into alkyl- and naphtheno-subtituted families. APCI proved more effective for the ionization of the highly saturated base oil components compared to APPI. Furthermore, for the detailed information on hydrocarbon molecules FT-ICR MS revealed the presence of saturated and aromatic sulfur species in all base oil samples. The results presented herein offer a unique perspective into the detailed molecular structure of base oils typically used to formulate lubricants. © 2015 American Chemical Society.

  18. Optimization of SMA layers in composite structures to enhance damping (United States)

    Haghdoust, P.; Cinquemani, S.; Lecis, N.; Bassani, P.


    The performance of lightweight structures can be severely affected by vibration. New design concepts leading to lightweight, slender structural components can increase the vulnerability of the components to failure due to excessive vibration. The intelligent approach to address the problem would be the use of materials which are more capable in dissipating the energy due to their high value of loss factor. Among the different materials available to achieve damping, much attention has been attached to the use of shape memory alloys (SMAs) because of their unique microstructure, leading to good damping capacity. This work describes the design and optimization of a hybrid layered composite structure for the passive suppression of flexural vibrations in slender and light structures. Embedding the SMA layers in composite structure allows to combine different properties: the lightness of the base composite (e.g. fiber glass), the mechanical strength of the insert of metallic material and the relevant damping properties of SMA, in the martensitic phase. In particular, we put our attention on embedding the CuZnAl in the form of thin sheet in a layered composite made by glass fiber reinforced epoxy. By appropriately positioning of the SMA sheets so that they are subjected to the maximum curvature, the damping of the hybrid system can be considerably enhanced. Accordingly analytical method for evaluating the energy dissipation of the thin sheets with different shapes and patterns is developed and is followed by a shape optimization based on genetic algorithm. Eventually different configurations of the hybrid beam structure with different patterns of SMA layer are proposed and compared in the term of damping capacity.

  19. Composite modelling of interactions between beaches and structures

    DEFF Research Database (Denmark)

    Gerritsen, Herman; Sutherland, James; Deigaard, Rolf


    An overview of Composite Modelling (CM) is presented, as elaborated in the EU/HYDRALAB joint research project Composite Modelling of the Interactions Between Beaches and Structures. An introduction and a review of the main literature on CM in the hydraulic community are given. In Section 3...... in the various case studies. The related subject of Good Modelling Practice is summarized in Section 5. Then guidelines are given on how to decide if CM may be beneficial, and how to set up a CM experiment. It is concluded that CM in the hydraulic community is still in its infancy but involves challenging...... research with significant potential....

  20. Laminated Ti-Al composites: Processing, structure and strength

    DEFF Research Database (Denmark)

    Du, Yan; Fan, Guohua; Yu, Tianbo


    . The mechanical properties of the composites with different volume fractions of Al from 10% to 67% show a good combination of strength and ductility. A constraint strain in the hot-rolled laminated structure between the hard and soft phases introduces an elastic-plastic deformation stage, which becomes more...... pronounced as the volume fraction of Al decreases. Moreover, the thin intermetallic interface layer may also contribute to the strength of the composites, and this effect increases with increasing volume fraction of the interface layer....

  1. Vanadium-spinel composites for structural applications in hostile environments

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, R.B.; Wetteland, C.J.; Shen, T.D. [and others


    Vanadium-spinel composites are promising materials for structural applications in radiation environments. Powders of two Vanadium-spinel composites, 20/80 vol. %, were prepared by (a) ball milling mixtures of vanadium and spinel powders (alloy VSLP) and (b) through a self-sustained reaction synthesis of vanadium, MgO, and Al powders (alloy VSHP). These powders were consolidated by hot isostatic pressing. Most of the V and spinel domains in the the compacts are sub-micron in size. The compacts have K{sub c} toughness values of 3.9, about three times the toughness obtained by hipping mixtures of commercial powders.

  2. Robust Joining and Integration Technologies for Advanced Metallic, Ceramic, and Composite Systems (United States)

    Singh, M.; Shpargel, Tarah; Morscher, Gregory N.; Halbig, Michael H.; Asthana, Rajiv


    Robust integration and assembly technologies are critical for the successful implementation of advanced metallic, ceramic, carbon-carbon, and ceramic matrix composite components in a wide variety of aerospace, space exploration, and ground based systems. Typically, the operating temperature of these components varies from few hundred to few thousand Kelvin with different working times (few minutes to years). The wide ranging system performance requirements necessitate the use of different integration technologies which includes adhesive bonding, low temperature soldering, active metal brazing, diffusion bonding, ARCJoinT, and ultra high temperature joining technologies. In this presentation, a number of joining examples and test results will be provided related to the adhesive bonding and active metal brazing of titanium to C/C composites, diffusion bonding of silicon carbide to silicon carbide using titanium interlayer, titanium and hastelloy brazing to silicon carbide matrix composites, and ARCJoinT joining of SiC ceramics and SiC matrix composites. Various issues in the joining of metal-ceramic systems including thermal expansion mismatch and resulting residual stresses generated during joining will be discussed. In addition, joint design and testing issues for a wide variety of joints will be presented.

  3. Biomechanical properties of an advanced new carbon/flax/epoxy composite material for bone plate applications. (United States)

    Bagheri, Zahra S; El Sawi, Ihab; Schemitsch, Emil H; Zdero, Rad; Bougherara, Habiba


    This work is part of an ongoing program to develop a new carbon fiber/flax/epoxy (CF/flax/epoxy) hybrid composite material for use as an orthopaedic long bone fracture plate, instead of a metal plate. The purpose of this study was to evaluate the mechanical properties of this new novel composite material. The composite material had a "sandwich structure", in which two thin sheets of CF/epoxy were attached to each outer surface of the flax/epoxy core, which resulted in a unique structure compared to other composite plates for bone plate applications. Mechanical properties were determined using tension, three-point bending, and Rockwell hardness tests. Also, scanning electron microscopy (SEM) was used to characterize the failure mechanism of specimens in tension and three-point bending tests. The results of mechanical tests revealed a considerably high ultimate strength in both tension (399.8MPa) and flexural loading (510.6MPa), with a higher elastic modulus in bending tests (57.4GPa) compared to tension tests (41.7GPa). The composite material experienced brittle catastrophic failure in both tension and bending tests. The SEM images, consistent with brittle failure, showed mostly fiber breakage and fiber pull-out at the fractured surfaces with perfect bonding at carbon fibers and flax plies. Compared to clinically-used orthopaedic metal plates, current CF/flax/epoxy results were closer to human cortical bone, making the material a potential candidate for use in long bone fracture fixation.

  4. Mechanistic Studies of Combustion and Structure Formation During Synthesis of Advanced Materials (United States)

    Varma, A.; Lau, C.; Mukasyan, A. S.


    Combustion in a variety of heterogeneous systems, leading to the synthesis of advanced materials, is characterized by high temperatures (2000-3500 K) and heating rates (up to 10(exp 6) K/s) at and ahead of the reaction front. These high temperatures generate liquids and gases which are subject to gravity-driven flow. The removal of such gravitational effects is likely to provide increased control of the reaction front, with a consequent improvement in control of the microstructure of the synthesized products. Thus, microgravity (mu-g) experiments lead to major advances in the understanding of fundamental aspects of combustion and structure formation under the extreme conditions of the combustion synthesis (CS) wave. In addition, the specific features of microgravity environment allow one to produce unique materials, which cannot be obtained under terrestrial conditions. The current research is a logic continuation of our previous work on investigations of the fundamental phenomena of combustion and structure formation that occur at the high temperatures achieved in a CS wave. Our research is being conducted in three main directions: 1) Microstructural Transformations during Combustion Synthesis of Metal-Ceramic Composites. The studies are devoted to the investigation of particle growth during CS of intermetallic-ceramic composites, synthesized from nickel, aluminum, titanium, and boron metal reactants. To determine the mechanisms of particle growth, the investigation varies the relative amount of components in the initial mixture to yield combustion wave products with different ratios of solid and liquid phases, under 1g and mu-g conditions; 2) Mechanisms of Heat Transfer during Reactions in Heterogeneous Media. Specifically, new phenomena of gasless combustion wave propagation in heterogeneous media with porosity higher than that achievable in normal gravity conditions, are being studied. Two types of mixtures are investigated: clad powders, where contact between

  5. Uncertainty Quantification in Experimental Structural Dynamics Identification of Composite Material Structures

    DEFF Research Database (Denmark)

    Luczak, Marcin; Peeters, Bart; Kahsin, Maciej


    Aerospace and wind energy structures are extensively using components made of composite materials. Since these structures are subjected to dynamic environments with time-varying loading conditions, it is important to model their dynamic behavior and validate these models by means of vibration...... for uncertainty evaluation in experimentally estimated models. Investigated structures are plates, fuselage panels and helicopter main rotor blades as they represent different complexity levels ranging from coupon, through sub-component up to fully assembled structures made of composite materials. To evaluate...

  6. Galerkin finite element scheme for magnetostrictive structures and composites (United States)

    Kannan, Kidambi Srinivasan

    The ever increasing-role of magnetostrictives in actuation and sensing applications is an indication of their importance in the emerging field of smart structures technology. As newer, and more complex, applications are developed, there is a growing need for a reliable computational tool that can effectively address the magneto-mechanical interactions and other nonlinearities in these materials and in structures incorporating them. This thesis presents a continuum level quasi-static, three-dimensional finite element computational scheme for modeling the nonlinear behavior of bulk magnetostrictive materials and particulate magnetostrictive composites. Models for magnetostriction must deal with two sources of nonlinearities-nonlinear body forces/moments in equilibrium equations governing magneto-mechanical interactions in deformable and magnetized bodies; and nonlinear coupled magneto-mechanical constitutive models for the material of interest. In the present work, classical differential formulations for nonlinear magneto-mechanical interactions are recast in integral form using the weighted-residual method. A discretized finite element form is obtained by applying the Galerkin technique. The finite element formulation is based upon three dimensional eight-noded (isoparametric) brick element interpolation functions and magnetostatic infinite elements at the boundary. Two alternative possibilities are explored for establishing the nonlinear incremental constitutive model-characterization in terms of magnetic field or in terms of magnetization. The former methodology is the one most commonly used in the literature. In this work, a detailed comparative study of both methodologies is carried out. The computational scheme is validated, qualitatively and quantitatively, against experimental measurements published in the literature on structures incorporating the magnetostrictive material Terfenol-D. The influence of nonlinear body forces and body moments of magnetic origin

  7. Use of microfasteners to produce damage tolerant composite structures. (United States)

    Partridge, Ivana K; Hallett, Stephen R


    The paper concerns the mechanical performance of continuous fibre/thermosetting polymer matrix composites reinforced in the through-thickness direction with fibrous or metallic rods or threads in order to mitigate against low delamination resistance. Specific illustrations of the effects of microfasteners in reducing delamination crack growth are made for Z-pinned and tufted composites. Response to loading in such 'structured materials' is subject to multiple parameters defining their in-plane and out-of-plane properties. Single microfastener mechanical tests are well suited to establish the crack bridging laws under a range of loading modes, from simple delamination crack opening to shear, and provide the basis for predicting the corresponding response of microfastener arrays, within a given material environment. The fundamental experiments on microfasteners can be used to derive analytical expressions to describe the crack bridging behaviour in a general sense, to cover all possible loadings. These expressions can be built into cohesive element constitutive laws in a finite-element framework for modelling the effects of microfastener arrays on the out-of-plane mechanical response of reinforced structural elements, including the effects of known manufacturing imperfections. Such predictive behaviour can then be used to assess structural integrity under complex loading, as part of the component design process. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

  8. Structure - property relations of high-temperature composite polymer matrices

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, R.J.; Jurek, R.J.; Larive, D.E. [Michigan Molecular Institute, Midland, MI (United States); Tung, C.M. [Northrop Corp., Hawthorne, CA (United States); Donnellan, T. [Naval Air Development Center, Warminster, PA (United States)


    The structure-deformation-failure mode-mechanical property relations of high-temperature thermoplastic polyimide and thermoset bismaleimide (BMI) polymeric matrices and their composites will be discussed. In the case of polyimides, the effects of test temperature, thermal history, strain rate, type of filler, and filler volume fraction on structure - property relations will be discussed. For BMIs we report systematic Fourier transform infrared spectroscopy and differential scanning calorimetry studies of the cure reactions as a function of chemical composition and time - temperature cure conditions and then describe the resultant cross-linked network structure based on our understanding of the cure reactions. The optimization of the BMI matrix toughness will be considered in terms of network structure and process-induced matrix microcracking. We also describe optimization of composite prepreg, lamination and postcure conditions based on cure kinetics, and their relationship to the BMI viscosity-time-temperature profiles. The critical processing-performance limitations of high-temperature polymer matrices will be critically discussed, and toughening approaches to address these limitations, such as toughness over a wide temperature range, will be presented. 7 refs., 2 figs., 1 tab.

  9. Activation and micropore structure of carbon-fiber composites

    Energy Technology Data Exchange (ETDEWEB)

    Jagtoyen, M.; Derbyshire, F.; Kimber, G. [Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research


    Rigid, high surface area activated carbon fiber composites have been produced with high permeabilities for environmental applications in gas and water purification. The project involves a collaboration between the Oak Ridge National Laboratory (ORNL) and the Center for Applied Energy Research (CAER), University of Kentucky. The main focus of recent work has been to find a satisfactory means to uniformly activate large samples of carbon fiber composites to produce controlled pore structures. Processes have been developed using activation in steam and CO{sub 2}, and a less conventional method involving oxygen chemisorption and subsequent heat treatment. Another objective has been to explore applications for the activated composites in environmental applications related to fossil energy production.

  10. Polyurethane structural adhesives applied in automotive composite joints

    Directory of Open Access Journals (Sweden)

    Josue Garcia Quini


    Full Text Available In recent years structural adhesives technology has demonstrated great potential for application due to its capacity to transform complex structures into solid unitary and monolithic assemblies using different materials. Thus, seams or joints integrate these structures providing, besides a reduction in weight, a considerable increase in the mechanical resistance and stiffness. The increase in the industrial use of structural adhesives is mainly due to their ability to efficiently bond different materials in an irreversible manner, even replacing systems involving mechanical joints. In the automobile industry structural adhesives have been widely used for the bonding of metal substrates, thermoplastics and composites, frequently employing these in combination, particularly glass fiber and polyester resin composites molded using RTM and SMC processes. However, the use of urethane structural adhesives in applications involving composites and thermoplastics has been the subject of few investigations. In this study the effects of temperature and time on the shear strength of RTM, SMC and ABS joints, applying temperatures of -40, 25, 80, 120 and 177 °C and times of 20 minutes and 500 hours, were determined. The objective was to evaluate the performance under extreme conditions of use in order to assess whether these joints could be used in passenger or off-road vehicles. The results showed that the urethane structural adhesive promoted the efficient bonding of these materials, considering that due to the high adhesive strength the failures occurred in the substrates without adversely affecting the bonded area. For each test condition the joint failure modes were also determined.

  11. Improve the performance of coated cemented hip stem through the advanced composite materials. (United States)

    Hedia, H S; Fouda, N


    Design of hip joint implant using functionally graded material (FGM) (advanced composite material) has been used before through few researches. It gives great results regarding the stress distribution along the implant and bone interfaces. However, coating of orthopaedic implants has been widely investigated through many researches. The effect of using advanced composite stem material, which mean by functionally graded stem material, in the total hip replacement coated with the most common coated materials has not been studied yet. Therefore, this study investigates the effect of utilizing these two concepts together; FGM and coating, in designing new stem material. It is concluded that the optimal FGM cemented stem is consisting from titanium at the upper stem layers graded to collagen at a lower stem layers. This optimal graded stem coated with hydroxyapatite found to reduce stress shielding by 57% compared to homogenous titanium stem coated with hydroxyapatite. However, the optimal functionally graded stem coated with collagen reduced the stress shielding by 51% compared to homogenous titanium stem coated with collagen.

  12. Microscopic structure and properties of wood-based foaming composites

    Institute of Scientific and Technical Information of China (English)

    Zheng WANG; Li GAO; Guilan ZHANG; Liang CHANG


    In order to reduce the density of wood-based composites without causing a deterioration of their mech-anical properties, we studied the process of manufacturing wood-based composites. A combination of polymer foaming technology and flat hot-pressing technology was used. The microscopic structure of the various wood-based composites was analyzed with a scanning electron microscope (SEM). Modulus of rupture (MOR), modulus of elasticity (MOE), impact strength, and thickness expansion rate of water sorption (TS) were all measured. The results showed that fibers loosely inter-weave, and fibers had been connected by micropore. They also showed that spaces between fibers had big micropore structure. MOR, MOE and impact strength were the high-est among three levels of ratio. When the total content of resin and foaming agent were 20% by weight, TS was higher. A hot-pressing temperature of 120℃ was optimal. At the low temperatures of 80℃, the foaming process was uncompleted. At a higher temperature, micropores burst at a certain pressure. Based on the variance analysis and maximum difference analysis, a significance test shows that the optimum conditions for the total content of resin and foaming agent is 20% by weight, with a hot pressing temperature of 120℃ for 15 min. Under these conditions, the properties of wood-based foaming composites all achieved the industry standard.

  13. Large Area Nondestructive Evaluation of a Fatigue Loaded Composite Structure (United States)

    Zalameda, Joseph N.; Burke, Eric R.; Horne, Michael R.; Madaras, Eric I.


    Large area nondestructive evaluation (NDE) inspections are required for fatigue testing of composite structures to track damage initiation and growth. Of particular interest is the progression of damage leading to ultimate failure to validate damage progression models. In this work, passive thermography and acoustic emission NDE were used to track damage growth up to failure of a composite three-stringer panel. Fourteen acoustic emission sensors were placed on the composite panel. The signals from the array were acquired simultaneously and allowed for acoustic emission location. In addition, real time thermal data of the composite structure were acquired during loading. Details are presented on the mapping of the acoustic emission locations directly onto the thermal imagery to confirm areas of damage growth leading to ultimate failure. This required synchronizing the acoustic emission and thermal data with the applied loading. In addition, processing of the thermal imagery which included contrast enhancement, removal of optical barrel distortion and correction of angular rotation before mapping the acoustic event locations are discussed.

  14. Structural and biological properties of carbon nanotube composite films

    Energy Technology Data Exchange (ETDEWEB)

    Narayan, Roger J. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)]. E-mail:; Berry, C.J. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States); Brigmon, R.L. [Environmental Biotechnology Section, Savannah River National Laboratory, Aiken, SC 29808 (United States)


    Carbon nanotube composite films have been developed that exhibit unusual structural and biological properties. These novel materials have been created by pulsed laser ablation of graphite and bombardment of nitrogen ions at temperatures between 600 and 700 deg. C. High-resolution transmission electron microscopy and radial distribution function analysis demonstrate that this material consists of sp{sup 2}-bonded concentric ribbons that are wrapped approximately 15 deg. normal to the silicon substrate. The interlayer order in this material extends to approximately 15-30 A. X-ray photoelectron spectroscopy and Raman spectroscopy data suggest that this material is predominantly trigonally coordinated. The carbon nanotube composite structure results from the use of energetic ions, which allow for non-equilibrium growth of graphitic planes. In vitro testing has revealed significant antimicrobial activity of carbon nanotube composite films against Staphylococcus aureus and Staphylococcus warneri colonization. Carbon nanotube composite films may be useful for inhibiting microorganism attachment and biofilm formation in hemodialysis catheters and other medical devices.

  15. Composite failure prediction of π-joint structures under bending

    Institute of Scientific and Technical Information of China (English)

    HUANG Hong-me; YUAN Shen-fang


    In this article,the composite π-joint is investigated under bending loads.The "L" preform is the critical component regarding composite π-joint failure.The study is presented in the failure detection of a carbon fiber composite π-joint structure under bending loads using fiber Bragg grating (FBG) sensor.Firstly,based on the general finite element method (FEM)software,the 3-D finite element (FE) model of composite π-joint is established,and the failure process and every lamina failure load of composite π-joint are investigated by maximum stress criteria.Then,strain distributions along the length of FBG are extracted,and the reflection spectra of FBG are calculated according to the strain distribution.Finally,to verify the numerical results,a test scheme is performed and the experimental spectra of FBG are recorded.The experimental results indicate that the failure sequence and the corresponding critical loads of failure are consistent with the numerical predictions,and the computational error of failure load is less than 6.4%.Furthermore,it also verifies the feasibility of the damage detection system.

  16. Composite Technology for Exploration (United States)

    Fikes, John


    The CTE (Composite Technology for Exploration) Project will develop and demonstrate critical composites technologies with a focus on joints that utilize NASA expertise and capabilities. The project will advance composite technologies providing lightweight structures to support future NASA exploration missions. The CTE project will demonstrate weight-saving, performance-enhancing bonded joint technology for Space Launch System (SLS)-scale composite hardware.

  17. Exposure to nanoscale particles and fibers during machining of hybrid advanced composites containing carbon nanotubes (United States)

    Bello, Dhimiter; Wardle, Brian L.; Yamamoto, Namiko; Guzman deVilloria, Roberto; Garcia, Enrique J.; Hart, Anastasios J.; Ahn, Kwangseog; Ellenbecker, Michael J.; Hallock, Marilyn


    This study investigated airborne exposures to nanoscale particles and fibers generated during dry and wet abrasive machining of two three-phase advanced composite systems containing carbon nanotubes (CNTs), micron-diameter continuous fibers (carbon or alumina), and thermoset polymer matrices. Exposures were evaluated with a suite of complementary instruments, including real-time particle number concentration and size distribution (0.005-20 μm), electron microscopy, and integrated sampling for fibers and respirable particulate at the source and breathing zone of the operator. Wet cutting, the usual procedure for such composites, did not produce exposures significantly different than background whereas dry cutting, without any emissions controls, provided a worst-case exposure and this article focuses here. Overall particle release levels, peaks in the size distribution of the particles, and surface area of released particles (including size distribution) were not significantly different for composites with and without CNTs. The majority of released particle surface area originated from the respirable (1-10 μm) fraction, whereas the nano fraction contributed 10% of the surface area. CNTs, either individual or in bundles, were not observed in extensive electron microscopy of collected samples. The mean number concentration of peaks for dry cutting was composite dependent and varied over an order of magnitude with highest values for thicker laminates at the source being >1 × 106 particles cm-3. Concentration of respirable fibers for dry cutting at the source ranged from 2 to 4 fibers cm-3 depending on the composite type. Further investigation is required and underway to determine the effects of various exposure determinants, such as specimen and tool geometry, on particle release and effectiveness of controls.

  18. Body composition, symptoms, and survival in advanced cancer patients referred to a phase I service.

    Directory of Open Access Journals (Sweden)

    Henrique A Parsons

    Full Text Available BACKGROUND: Body weight and body composition are relevant to the outcomes of cancer and antineoplastic therapy. However, their role in Phase I clinical trial patients is unknown. METHODS: We reviewed symptom burden, body composition, and survival in 104 patients with advanced cancer referred to a Phase I oncology service. Symptom burden was analyzed using the MD Anderson Symptom Assessment Inventory(MDASI; body composition was evaluated utilizing computerized tomography(CT images. A body mass index (BMI≥25 kg/m² was considered overweight. Sarcopenia, severe muscle depletion, was assessed using CT-based criteria. RESULTS: Most patients were overweight (n = 65, 63%; 53 patients were sarcopenic (51%, including 79% of patients with a BMI<25 kg/m² and 34% of those with BMI≥25 kg/m². Sarcopenic patients were older and less frequently African-American. Symptom burden did not differ among patients classified according to BMI and presence of sarcopenia. Median (95% confidence interval survival (days varied according to body composition: 215 (71-358 (BMI<25 kg/m²; sarcopenic, 271 (99-443 (BMI<25 kg/m²; non-sarcopenic, 484 (286-681 (BMI≥25 kg/m²; sarcopenic; 501 d (309-693 (BMI≥25 kg/m²; non-sarcopenic. Higher muscle index and gastrointestinal cancer diagnosis predicted longer survival in multivariate analysis after controlling for age, gender, performance status, and fat index. CONCLUSIONS: Patients referred to a Phase I clinic had a high frequency of sarcopenia and a BMI≥25 kg/m², independent of symptom burden. Body composition variables were predictive of clinically relevant survival differences, which is potentially important in developing Phase I studies.

  19. Unambiguous UML Composite Structures: The OMEGA2 Experience (United States)

    Ober, Iulian; Dragomir, Iulia

    Starting from version 2.0, UML introduced hierarchical composite structures, which are a very expressive way of defining complex software architectures, but which have a very loosely defined semantics in the standard. In this paper we propose a set of consistency rules that ensure UML composite structures are unambiguous and can be given a precise semantics. Our primary application of the static consistency rules defined in this paper is within the OMEGA UML profile [6], but these rules are general and applicable to other hierarchical component models based on the same concepts, such as MARTE GCM or SysML. The rule set has been formalized in OCL and is currently used in the OMEGA UML compiler.

  20. Structural Intensity Characterization of Composite Laminates Subjected to Impact Load

    Institute of Scientific and Technical Information of China (English)

    WANG Dong-fang; HE Peng-fei; LIU Zi-shun


    Structural intensity (SI) characterization of composite laminates subjected to impact load was dis-cussed. The SI pattern of the laminates which have different fiber orientations and boundary conditions wasanalyzed. The resultant forces and velocities of the laminates were calculated, and the structural intensity wasevaluated. The SI streamlines of carbon fiber reinforced epoxy composite laminates and the steel plates werediscussed. The results show that the SI streamlines of the graphite/epoxy laminates are different from that ofthe steel plates, and the SI streamlines are influenced by the boundaries, the stacking sequence of the compositelaminates. The change of the historical central displacement of the graphite/epoxy laminates is fasten thanthat of the steel plates.

  1. Freeform fabrication of polymer-matrix composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Kaufman, S.G.; Spletzer, B.L.; Guess, T.L.


    The authors have developed, prototyped, and demonstrated the feasibility of a novel robotic technique for rapid fabrication of composite structures. Its chief innovation is that, unlike all other available fabrication methods, it does not require a mold. Instead, the structure is built patch by patch, using a rapidly reconfigurable forming surface, and a robot to position the evolving part. Both of these components are programmable, so only the control software needs to be changed to produce a new shape. Hence it should be possible to automatically program the system to produce a shape directly from an electronic model of it. It is therefore likely that the method will enable faster and less expensive fabrication of composites.

  2. Properties and Structure of Microcrystal Muscovite Composite Superabsorbent

    Institute of Scientific and Technical Information of China (English)

    WAN Tao; XIONG Lei; HUANG Runqiu; SUN Mengmeng; QIN Lili; TAN Xuemei; HU Junyan


    Microcrystal muscovite composite superabsorbents (MMCSA) were prepared by water solution polymerization using acrylic acid, acrylamide and itaconic acid as comonomers and microcrystal muscovite as an inorganic additive. Properties, such as water absorbency, salt absorbency, gel strength, water retention capacity and structure of MMCSA characterized by SEM and XRD, were investigated. Water absorbency, salt absorbency, gel strength, water retention capacity and thermostability were enhanced by incorporation of suitable amount of microcrystal muscovite. Water absorption of MMCSA was rapid, requiring 24.55 min to reach 63% of equilibrium absorbency (1218 g/g). Microcrystal muscovite was physically combined into the polymeric network without destroying its polycrystalline structure and microcrystal muscovite composite superabsorbent had some irregular, undulant, and small microporous holes with sheet-like microcrystal muscovite distributed in the polymeric matrix.


    Energy Technology Data Exchange (ETDEWEB)

    Reinard, Alysha A. [University of Colorado/Cooperative Institute for Research in Environmental Sciences and National Oceanic and Atmospheric Administration/Space Weather Prediction Center, Boulder, CO 80505 (United States); Lynch, Benjamin J. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Mulligan, Tamitha, E-mail:, E-mail:, E-mail: [Space Sciences Department, Aerospace Corporation, Los Angeles, CA 90009 (United States)


    We present an analysis of the ionic composition of iron for two interplanetary coronal mass ejections (ICMEs) observed on 2007 May 21-23 by the ACE and STEREO spacecraft in the context of the magnetic structure of the ejecta flux rope, sheath region, and surrounding solar wind flow. This analysis is made possible due to recent advances in multispacecraft data interpolation, reconstruction, and visualization as well as results from recent modeling of ionic charge states in MHD simulations of magnetic breakout and flux cancellation coronal mass ejection (CME) initiation. We use these advances to interpret specific features of the ICME plasma composition resulting from the magnetic topology and evolution of the CME. We find that, in both the data and our MHD simulations, the flux ropes centers are relatively cool, while charge state enhancements surround and trail the flux ropes. The magnetic orientations of the ICMEs are suggestive of magnetic breakout-like reconnection during the eruption process, which could explain the spatial location of the observed iron enhancements just outside the traditional flux rope magnetic signatures and between the two ICMEs. Detailed comparisons between the simulations and data were more complicated, but a sharp increase in high iron charge states in the ACE and STEREO-A data during the second flux rope corresponds well to similar features in the flux cancellation results. We discuss the prospects of this integrated in situ data analysis and modeling approach to advancing our understanding of the unified CME-to-ICME evolution.

  4. Certification Testing Methodology for Composite Structure. Volume 2. Methodology Development (United States)


    regime. The lesson learned from these experiences is that composite structures are much more sensitive to secondary load induced hot spots than metals...unexpected hot spot failures from secondary out-of-plane loads. A room temperature enviroment is therefore recommended for full scale static test...static strength data. The reliability depends on the maximum spectrum load, the spectrum characteris- tics , SRV and the static failure load. 5. Determine

  5. Health monitoring studies on composite structures for aerospace applications

    Energy Technology Data Exchange (ETDEWEB)

    James, G.; Roach, D.; Hansche, B.; Meza, R.; Robinson, N.


    This paper discusses ongoing work to develop structural health monitoring techniques for composite aerospace structures such as aircraft control surfaces, fuselage sections or repairs, and reusable launch vehicle fuel tanks. The overall project is divided into four tasks: Operational evaluation, diagnostic measurements, information condensation, and damage detection. Five composite plates were constructed to study delaminations, disbonds, and fluid retention issues as the initial step in creating an operational system. These four square feet plates were graphite-epoxy with nomex honeycomb cores. The diagnostic measurements are composed of modal tests with a scanning laser vibrometer at over 500 scan points per plate covering the frequency range up to 2000 Hz. This data has been reduced into experimental dynamics matrices using a generic, software package developed at the University of Colorado at Boulder. The continuing effort will entail performing a series of damage identification studies to detect, localize, and determine the extent of the damage. This work is providing understanding and algorithm development for a global NDE technique for composite aerospace structures.

  6. Recent developments of discrete material optimization of laminated composite structures

    DEFF Research Database (Denmark)

    Lund, Erik; Sørensen, Rene


    This work will give a quick summary of recent developments of the Discrete Material Optimization approach for structural optimization of laminated composite structures. This approach can be seen as a multi-material topology optimization approach for selecting the best ply material and number....... The different interpolation schemes used are described, and it is briefly outlined how design rules/manufacturing constraints can be included in the optimization. The approach has been demonstrated for a number of global design criteria like mass, compliance, buckling load factors, etc., but recent work makes...

  7. Deterministic aperiodic composite lattice-structured silicon thin films for photon management

    CERN Document Server

    Xavier, Jolly; Becker, Christiane


    Exotic manipulation of the flow of photons in nanoengineered semiconductor materials with an aperiodic distribution of nanostructures plays a key role in efficiency-enhanced and industrially viable broadband photonic technologies. Through a generic deterministic nanotechnological route, in addition to periodic, transversely quasicrystallographic or disordered random photonic lattices, here we show scalable nanostructured semiconductor thin films on large area nanoimprinted substrates up to 4cm^2 with advanced functional features of aperiodic composite nanophotonic lattices having tailorable supercell tiles. The richer Fourier spectra of the presented artificially nanostructured materials with well-defined lattice point morphologies are designed functionally akin to two-dimensional incommensurate intergrowth aperiodic lattices-comprising periodic photonic crystals and in-plane quasicrystals as subgroups. The composite photonic lattice-structured crystalline silicon thin films with tapered nanoholes or nanocone...

  8. Nonlinear damage detection in composite structures using bispectral analysis (United States)

    Ciampa, Francesco; Pickering, Simon; Scarselli, Gennaro; Meo, Michele


    Literature offers a quantitative number of diagnostic methods that can continuously provide detailed information of the material defects and damages in aerospace and civil engineering applications. Indeed, low velocity impact damages can considerably degrade the integrity of structural components and, if not detected, they can result in catastrophic failure conditions. This paper presents a nonlinear Structural Health Monitoring (SHM) method, based on ultrasonic guided waves (GW), for the detection of the nonlinear signature in a damaged composite structure. The proposed technique, based on a bispectral analysis of ultrasonic input waveforms, allows for the evaluation of the nonlinear response due to the presence of cracks and delaminations. Indeed, such a methodology was used to characterize the nonlinear behaviour of the structure, by exploiting the frequency mixing of the original waveform acquired from a sparse array of sensors. The robustness of bispectral analysis was experimentally demonstrated on a damaged carbon fibre reinforce plastic (CFRP) composite panel, and the nonlinear source was retrieved with a high level of accuracy. Unlike other linear and nonlinear ultrasonic methods for damage detection, this methodology does not require any baseline with the undamaged structure for the evaluation of the nonlinear source, nor a priori knowledge of the mechanical properties of the specimen. Moreover, bispectral analysis can be considered as a nonlinear elastic wave spectroscopy (NEWS) technique for materials showing either classical or non-classical nonlinear behaviour.

  9. Structural integrity of engineering composite materials: a cracking good yarn. (United States)

    Beaumont, Peter W R; Soutis, Costas


    Predicting precisely where a crack will develop in a material under stress and exactly when in time catastrophic fracture of the component will occur is one the oldest unsolved mysteries in the design and building of large-scale engineering structures. Where human life depends upon engineering ingenuity, the burden of testing to prove a 'fracture safe design' is immense. Fitness considerations for long-life implementation of large composite structures include understanding phenomena such as impact, fatigue, creep and stress corrosion cracking that affect reliability, life expectancy and durability of structure. Structural integrity analysis treats the design, the materials used, and figures out how best components and parts can be joined, and takes service duty into account. However, there are conflicting aims in the complete design process of designing simultaneously for high efficiency and safety assurance throughout an economically viable lifetime with an acceptable level of risk. This article is part of the themed issue 'Multiscale modelling of the structural integrity of composite materials'.

  10. Plasma-modified graphene nanoplatelets and multiwalled carbon nanotubes as fillers for advanced rubber composites (United States)

    Sicinski, M.; Gozdek, T.; Bielinski, D. M.; Szymanowski, H.; Kleczewska, J.; Piatkowska, A.


    In modern rubber industry, there still is a room for new fillers, which can improve the mechanical properties of the composites, or introduce a new function to the material. Modern fillers like carbon nanotubes or graphene nanoplatelets (GnP), are increasingly applied in advanced polymer composites technology. However, it might be hard to obtain a well dispersed system for such systems. The polymer matrix often exhibits higher surface free energy (SFE) level with the filler, which can cause problems with polymer-filler interphase adhesion. Filler particles are not wet properly by the polymer, and thus are easier to agglomerate. As a consequence, improvement in the mechanical properties is lower than expected. In this work, multi-walled carbon nanotubes (MWCNT) and GnP surface were modified with low-temperature plasma. Attempts were made to graft some functionalizing species on plasma-activated filler surface. The analysis of virgin and modified fillers’ SFE was carried out. MWCNT and GnP rubber composites were produced, and ultimately, their morphology and mechanical properties were studied.

  11. Selection process for trade study: Graphite Composite Primary Structure (GCPS) (United States)

    Greenberg, H. S.


    This TA 2 document describes the selection process that will be used to identify the most suitable structural configuration for an SSTO winged vehicle capable of delivering 25,000 lbs to a 220 nm circular orbit at 51.6 degree inclination. The most suitable unpressurized graphite composite structures and material selections is within this configuration and will be the prototype design for subsequent design and analysis and the basis for the design and fabrication of payload bay, wing, and thrust structure full scale test articles representing segments of the prototype structures. The selection process for this TA 2 trade study is the same as that for the TA 1 trade study. As the trade study progresses additional insight may result in modifications to the selection criteria within this process. Such modifications will result in an update of this document as appropriate.

  12. CARAPACE: a novel composite advanced robotic actuator powering assistive compliant exoskeleton: preliminary design. (United States)

    Masia, Lorenzo; Cappello, Leonardo; Morasso, Pietro; Lachenal, Xavier; Pirrera, Alberto; Weaver, Paul; Mattioni, Filippo


    A novel actuator is introduced that combines an elastically compliant composite structure with conventional electromechanical elements. The proposed design is analogous to that used in Series Elastic Actuators, its distinctive feature being that the compliant composite part offers different stable configurations. In other words, its elastic potential presents points of local minima that correspond to robust stable positions (multistability). This potential is known a priori as a function of the structural geometry, thus providing tremendous benefits in terms of control implementation. Such knowledge enables the complexities arising from the additional degrees of freedom associated with link deformations to be overcome and uncover challenges that extends beyond those posed by standard rigidlink robot dynamics. It is thought that integrating a multistable elastic element in a robotic transmission can provide new scenarios in the field of assistive robotics, as the system may help a subject to stand or carry a load without the need for an active control effort by the actuators.

  13. Damage Assessment of Composite Structures Using Digital Image Correlation (United States)

    Caminero, M. A.; Lopez-Pedrosa, M.; Pinna, C.; Soutis, C.


    The steady increase of Carbon-Fiber Reinforced Polymer (CFRP) Structures in modern aircraft will reach a new dimension with the entry into service of the Boeing 787 and Airbus 350. Replacement of damaged parts will not be a preferable solution due to the high level of integration and the large size of the components involved. Consequently the need to develop repair techniques and processes for composite components is readily apparent. Bonded patch repair technologies provide an alternative to mechanically fastened repairs with significantly higher performance, especially for relatively thin skins. Carefully designed adhesively bonded patches can lead to cost effective and highly efficient repairs in comparison with conventional riveted patch repairs that cut fibers and introduce highly strained regions. In this work, the assessment of the damage process taking place in notched (open-hole) specimens under uniaxial tensile loading was studied. Two-dimensional (2D) and three-dimensional (3D) Digital Image Correlation (DIC) techniques were employed to obtain full-field surface strain measurements in carbon-fiber/epoxy T700/M21 composite plates with different stacking sequences in the presence of an open circular hole. Penetrant enhanced X-ray radiographs were taken to identify damage location and extent after loading around the hole. DIC strain fields were compared to finite element predictions. In addition, DIC techniques were used to characterise damage and performance of adhesively bonded patch repairs in composite panels under tensile loading. This part of work relates to strength/stiffness restoration of damaged composite aircraft that becomes more important as composites are used more extensively in the construction of modern jet airliners. The behaviour of bonded patches under loading was monitored using DIC full-field strain measurements. Location and extent of damage identified by X-ray radiography correlates well with DIC strain results giving confidence to

  14. Advancement of Compositional and Microstructural Design of Intermetallic γ-TiAl Based Alloys Determined by Atom Probe Tomography

    Directory of Open Access Journals (Sweden)

    Thomas Klein


    Full Text Available Advanced intermetallic alloys based on the γ-TiAl phase have become widely regarded as most promising candidates to replace heavier Ni-base superalloys as materials for high-temperature structural components, due to their facilitating properties of high creep and oxidation resistance in combination with a low density. Particularly, recently developed alloying concepts based on a β-solidification pathway, such as the so-called TNM alloy, which are already incorporated in aircraft engines, have emerged offering the advantage of being processible using near-conventional methods and the option to attain balanced mechanical properties via subsequent heat-treatment. Development trends for the improvement of alloying concepts, especially dealing with issues regarding alloying element distribution, nano-scale phase characterization, phase stability, and phase formation mechanisms demand the utilization of high-resolution techniques, mainly due to the multi-phase nature of advanced TiAl alloys. Atom probe tomography (APT offers unique possibilities of characterizing chemical compositions with a high spatial resolution and has, therefore, been widely used in recent years with the aim of understanding the materials constitution and appearing basic phenomena on the atomic scale and applying these findings to alloy development. This review, thus, aims at summarizing scientific works regarding the application of atom probe tomography towards the understanding and further development of intermetallic TiAl alloys.

  15. Comparative Study of 3-Dimensional Woven Joint Architectures for Composite Spacecraft Structures (United States)

    Jones, Justin S.; Polis, Daniel L.; Rowles, Russell R.; Segal, Kenneth N.


    The National Aeronautics and Space Administration (NASA) Exploration Systems Mission Directorate initiated an Advanced Composite Technology (ACT) Project through the Exploration Technology Development Program in order to support the polymer composite needs for future heavy lift launch architectures. As an example, the large composite structural applications on Ares V inspired the evaluation of advanced joining technologies, specifically 3D woven composite joints, which could be applied to segmented barrel structures needed for autoclave cured barrel segments due to autoclave size constraints. Implementation of these 3D woven joint technologies may offer enhancements in damage tolerance without sacrificing weight. However, baseline mechanical performance data is needed to properly analyze the joint stresses and subsequently design/down-select a preform architecture. Six different configurations were designed and prepared for this study; each consisting of a different combination of warp/fill fiber volume ratio and preform interlocking method (Z-fiber, fully interlocked, or hybrid). Tensile testing was performed for this study with the enhancement of a dual camera Digital Image Correlation (DIC) system which provides the capability to measure full-field strains and three dimensional displacements of objects under load. As expected, the ratio of warp/fill fiber has a direct influence on strength and modulus, with higher values measured in the direction of higher fiber volume bias. When comparing the Z-fiber weave to a fully interlocked weave with comparable fiber bias, the Z-fiber weave demonstrated the best performance in two different comparisons. We report the measured tensile strengths and moduli for test coupons from the 6 different weave configurations under study.

  16. Multi-physics damage sensing in nano-engineered structural composites. (United States)

    de Villoria, Roberto Guzmán; Yamamoto, Namiko; Miravete, Antonio; Wardle, Brian L


    Non-destructive evaluation techniques can offer viable diagnostic and prognostic routes to mitigating failures in engineered structures such as bridges, buildings and vehicles. However, existing techniques have significant drawbacks, including poor spatial resolution and limited in situ capabilities. We report here a novel approach where structural advanced composites containing electrically conductive aligned carbon nanotubes (CNTs) are ohmically heated via simple electrical contacts, and damage is visualized via thermographic imaging. Damage, in the form of cracks and other discontinuities, usefully increases resistance to both electrical and thermal transport in these materials, which enables tomographic full-field damage assessment in many cases. Characteristics of the technique include the ability for real-time measurement of the damage state during loading, low-power operation (e.g. 15 °C rise at 1 W), and beyond state-of-the-art spatial resolution for sensing damage in composites. The enhanced thermographic technique is a novel and practical approach for in situ monitoring to ascertain structural health and to prevent structural failures in engineered structures such as aerospace and automotive vehicles and wind turbine blades, among others.

  17. Multi-physics damage sensing in nano-engineered structural composites (United States)

    Guzmán de Villoria, Roberto; Yamamoto, Namiko; Miravete, Antonio; Wardle, Brian L.


    Non-destructive evaluation techniques can offer viable diagnostic and prognostic routes to mitigating failures in engineered structures such as bridges, buildings and vehicles. However, existing techniques have significant drawbacks, including poor spatial resolution and limited in situ capabilities. We report here a novel approach where structural advanced composites containing electrically conductive aligned carbon nanotubes (CNTs) are ohmically heated via simple electrical contacts, and damage is visualized via thermographic imaging. Damage, in the form of cracks and other discontinuities, usefully increases resistance to both electrical and thermal transport in these materials, which enables tomographic full-field damage assessment in many cases. Characteristics of the technique include the ability for real-time measurement of the damage state during loading, low-power operation (e.g. 15 °C rise at 1 W), and beyond state-of-the-art spatial resolution for sensing damage in composites. The enhanced thermographic technique is a novel and practical approach for in situ monitoring to ascertain structural health and to prevent structural failures in engineered structures such as aerospace and automotive vehicles and wind turbine blades, among others.

  18. Design and Optimization of a Composite Canard Control Surface of an Advanced Fighter Aircraft under Static Loading

    Directory of Open Access Journals (Sweden)

    Shrivastava Sachin


    Full Text Available The minimization of weight and maximization of payload is an ever challenging design procedure for air vehicles. The present study has been carried out with an objective to redesign control surface of an advanced all-metallic fighter aircraft. In this study, the structure made up of high strength aluminum, titanium and ferrous alloys has been attempted to replace by carbon fiber composite (CFC skin, ribs and stiffeners. This study presents an approach towards development of a methodology for optimization of first-ply failure index (FI in unidirectional fibrous laminates using Genetic-Algorithms (GA under quasi-static loading. The GAs, by the application of its operators like reproduction, cross-over, mutation and elitist strategy, optimize the ply-orientations in laminates so as to have minimum FI of Tsai-Wu first-ply failure criterion. The GA optimization procedure has been implemented in MATLAB and interfaced with commercial software ABAQUS using python scripting. FI calculations have been carried out in ABAQUS with user material subroutine (UMAT. The GA's application gave reasonably well-optimized ply-orientations combination at a faster convergence rate. However, the final optimized sequence of ply-orientations is obtained by tweaking the sequences given by GA's based on industrial practices and experience, whenever needed. The present study of conversion of an all metallic structure to partial CFC structure has led to 12% of weight reduction. Therefore, the approach proposed here motivates designer to use CFC with a confidence.

  19. Advanced methods of continuum mechanics for materials and structures

    CERN Document Server

    Aßmus, Marcus


    This volume presents a collection of contributions on advanced approaches of continuum mechanics, which were written to celebrate the 60th birthday of Prof. Holm Altenbach. The contributions are on topics related to the theoretical foundations for the analysis of rods, shells and three-dimensional solids, formulation of constitutive models for advanced materials, as well as development of new approaches to the modeling of damage and fractures.

  20. Nepheline structural and chemical dependence on melt composition

    Energy Technology Data Exchange (ETDEWEB)

    Marcial, José; Crum, Jarrod; Neill, Owen; McCloy, John


    Nepheline crystallizes upon slow-cooling in some melts concentrated in Na2O and Al2O3, which can result in a residual glass phase of low chemical durability. Nepheline can incorporate many components often found in high-level waste radioactive borosilicate glass, including glass network ions (e.g., Si, Al, Fe), alkali metals (e.g., Cs, K, Na, and possibly Li), alkaline-earth metals (e.g., Ba, Sr, Ca, Mg), and transition metals (e.g., Mn, and possibly Cr, Zn, Ni). When crystallized from melts of different compositions, nepheline chemistry varies as a function of starting glass composition. Five simulated high level nuclear waste borosilicate glasses shown to crystallize large fractions of nepheline on slow cooling, were selected for study. These melts constituted a range of Al2O3, B2O3, CaO, Na2O, K2O, Fe2O3, and SiO2 compositions. Compositional analyses of nepheline crystals in glass by electron probe micro-analysis (EPMA) indicate that boron is unlikely to be present in any significant concentration, if at all, in nepheline. Also, several models are presented for calculating the fraction of vacancies in the nepheline structure.

  1. Asymptotic Analysis of Fiber-Reinforced Composites of Hexagonal Structure (United States)

    Kalamkarov, Alexander L.; Andrianov, Igor V.; Pacheco, Pedro M. C. L.; Savi, Marcelo A.; Starushenko, Galina A.


    The fiber-reinforced composite materials with periodic cylindrical inclusions of a circular cross-section arranged in a hexagonal array are analyzed. The governing analytical relations of the thermal conductivity problem for such composites are obtained using the asymptotic homogenization method. The lubrication theory is applied for the asymptotic solution of the unit cell problems in the cases of inclusions of large and close to limit diameters, and for inclusions with high conductivity. The lubrication method is further generalized to the cases of finite values of the physical properties of inclusions, as well as for the cases of medium-sized inclusions. The analytical formulas for the effective coefficient of thermal conductivity of the fiber-reinforced composite materials of a hexagonal structure are derived in the cases of small conductivity of inclusions, as well as in the cases of extremely low conductivity of inclusions. The three-phase composite model (TPhM) is applied for solving the unit cell problems in the cases of the inclusions with small diameters, and the asymptotic analysis of the obtained solutions is performed for inclusions of small sizes. The obtained results are analyzed and illustrated graphically, and the limits of their applicability are evaluated. They are compared with the known numerical and asymptotic data in some particular cases, and very good agreement is demonstrated.

  2. Integration of fluidic jet actuators in composite structures (United States)

    Schueller, Martin; Lipowski, Mathias; Schirmer, Eckart; Walther, Marco; Otto, Thomas; Geßner, Thomas; Kroll, Lothar


    Fluidic Actuated Flow Control (FAFC) has been introduced as a technology that influences the boundary layer by actively blowing air through slots or holes in the aircraft skin or wind turbine rotor blade. Modern wing structures are or will be manufactured using composite materials. In these state of the art systems, AFC actuators are integrated in a hybrid approach. The new idea is to directly integrate the active fluidic elements (such as SJAs and PJAs) and their components in the structure of the airfoil. Consequently, the integration of such fluidic devices must fit the manufacturing process and the material properties of the composite structure. The challenge is to integrate temperature-sensitive active elements and to realize fluidic cavities at the same time. The transducer elements will be provided for the manufacturing steps using roll-to-roll processes. The fluidic parts of the actuators will be manufactured using the MuCell® process that provides on the one hand the defined reproduction of the fluidic structures and, on the other hand, a high light weight index. Based on the first design concept, a demonstrator was developed in order to proof the design approach. The output velocity on the exit was measured using a hot-wire anemometer.

  3. Active structural health monitoring of composite plates and sandwiches

    Directory of Open Access Journals (Sweden)

    Sadílek P.


    Full Text Available The aim of presented work is to design, assemble and test a functional system, that is able to reveal damage from impact loading. This is done by monitoring of change of spectral characteristics on a damaged structure that is caused by change of mechanical properties of material or by change of structure’s geometry. Excitation and monitoring of structures was done using piezoelectric patches. Unidirectional composite plate was tested for eigenfrequencies using chirp signal. The eigenfrequencies were compared to results from experiments with an impact hammer and consequently with results from finite element method. Same method of finding eigenfrequencies was used on a different unidirectional composite specimen. Series of impacts were performed. Spectrum of eigenfrequencies was measured on undamaged plate and then after each impact. Measurements of the plate with different level of damage were compared. Following experiments were performed on sandwich materials where more different failures may happen. Set of sandwich beams (cut out from one plate made of two outer composite layers and a foam core was investigated and subjected to several impacts. Several samples were impacted in the same manner to get comparable results. The impacts were performed with growing impact energy.


    Directory of Open Access Journals (Sweden)

    Romashova Olga Vladimirovna


    Full Text Available The article deals with the compositional and substantial structure of the ambulatory medical record, or "case history", which has being formed for a long time. The author allocates the three main periods in the formation of this medical document: the first period (the beginning of the 19th century – 1920s is connected with the origin and formation; the second period (1920-1980s is marked by emergence of the normative legal acts regulating registration and maintaining; the third period (1980s – up to the present is associated with the cancellation of regulations and the introduction of the new order of the Ministry of Health of the USSR that changed the document's form and name. It is determined that the composition of the case history consists of the title page and the main part. The following processes take place in the course of ambulatory medical record's formation: strengthening formalization, increase in the number of pattern text fragments, increase in the text's volume, and the implementation of bigger number of functions. The author reveals the main (informative and cumulative, accounting and additional (scientific, controlling, legal, financial functions of the document. The implementation of these functions is reflected in the compositional and substantial structure of the document text and is conditioned by a number of extralinguistic factors.

  5. Composition, structure and mechanical properties of several natural cellular materials

    Institute of Scientific and Technical Information of China (English)


    The stem piths of sunflower, kaoliang and corn are natural cellular materials. In this paper, the contents of the compositions of these piths are determined and their cell shapes and structures are examined through scanning electron microscope (SEM) and optical microscope. Further research is conducted in the effects of the compositions and structures of the piths on the mechanical properties after testing the partial mechanical properties. The results show that the total cellulose, hemicelluloses and lignin content of each sample approaches 75% of the dry mass of its primary cell walls. With the fall of R value, a parameter relative to the contents of the main compositions, the flexibilities of the cellular piths descend while their stresses and rigidities increase. The basic cell shape making up the sunflower pith is approximately a tetrakaidehedron. The stem piths of kaoliang and corn are made up of cells close to hexangular prisms and a few tubular ones which can observably reinforce their mechanical properties in the axial directions.

  6. Caul and method for bonding and curing intricate composite structures (United States)

    Willden, Kurtis S. (Inventor); Goodno, Kenneth N. (Inventor)


    The invention disclosed here is a method for forming and curing an intricate structure of criss-crossing composite stringers and frames that are bonded to a skin panel. A structure constructed in accordance with the invention would be well-suited for use as a portion of an aircraft fuselage, a boat hull, or the like. The method is preferably practiced by applying uncured composite stringers to an uncured composite sheet panel. This is followed by placing cured frames crosswise over the stringers. The frames have openings at the locations where they intersect with the stringers which enables the frames to come into direct contact with the skin along most of their length. During the forming and curing process, the stringers are covered with a plurality of cauls, and the entire assembly of skin panel, stringers, frames and cauls is subjected to a vacuum bagging and curing process. The cauls serve to maintain both part shape and to control the flow of resin within the stringers as they are cured. Further, they probably eliminate the need for intermediate protective materials between the vacuum bag and the stringers.

  7. Durability-Based Design Guide for an Automotive Structural Composite: Part 2. Background Data and Models

    Energy Technology Data Exchange (ETDEWEB)

    Corum, J.M. [ORNL; Battiste, R.L. [ORNL; Brinkman, C.R. [ORNL; Ren, W. [ORNL; Ruggles, M.B. [ORNL; Weitsman, Y.J. [ORNL; Yahr, G.T. [ORNL


    This background report is a companion to the document entitled ''Durability-Based Design Criteria for an Automotive Structural Composite: Part 1. Design Rules'' (ORNL-6930). The rules and the supporting material characterization and modeling efforts described here are the result of a U.S. Department of Energy Advanced Automotive Materials project entitled ''Durability of Lightweight Composite Structures.'' The overall goal of the project is to develop experimentally based, durability-driven design guidelines for automotive structural composites. The project is closely coordinated with the Automotive Composites Consortium (ACC). The initial reference material addressed by the rules and this background report was chosen and supplied by ACC. The material is a structural reaction injection-molded isocyanurate (urethane), reinforced with continuous-strand, swirl-mat, E-glass fibers. This report consists of 16 position papers, each summarizing the observations and results of a key area of investigation carried out to provide the basis for the durability-based design guide. The durability issues addressed include the effects of cyclic and sustained loadings, temperature, automotive fluids, vibrations, and low-energy impacts (e.g., tool drops and roadway kickups) on deformation, strength, and stiffness. The position papers cover these durability issues. Topics include (1) tensile, compressive, shear, and flexural properties; (2) creep and creep rupture; (3) cyclic fatigue; (4) the effects of temperature, environment, and prior loadings; (5) a multiaxial strength criterion; (6) impact damage and damage tolerance design; (7) stress concentrations; (8) a damage-based predictive model for time-dependent deformations; (9) confirmatory subscale component tests; and (10) damage development and growth observations.

  8. Fiber Bragg Grating Sensor System for Monitoring Smart Composite Aerospace Structures (United States)

    Moslehi, Behzad; Black, Richard J.; Gowayed, Yasser


    Lightweight, electromagnetic interference (EMI) immune, fiber-optic, sensor- based structural health monitoring (SHM) will play an increasing role in aerospace structures ranging from aircraft wings to jet engine vanes. Fiber Bragg Grating (FBG) sensors for SHM include advanced signal processing, system and damage identification, and location and quantification algorithms. Potentially, the solution could be developed into an autonomous onboard system to inspect and perform non-destructive evaluation and SHM. A novel method has been developed to massively multiplex FBG sensors, supported by a parallel processing interrogator, which enables high sampling rates combined with highly distributed sensing (up to 96 sensors per system). The interrogation system comprises several subsystems. A broadband optical source subsystem (BOSS) and routing and interface module (RIM) send light from the interrogation system to a composite embedded FBG sensor matrix, which returns measurand-dependent wavelengths back to the interrogation system for measurement with subpicometer resolution. In particular, the returned wavelengths are channeled by the RIM to a photonic signal processing subsystem based on powerful optical chips, then passed through an optoelectronic interface to an analog post-detection electronics subsystem, digital post-detection electronics subsystem, and finally via a data interface to a computer. A range of composite structures has been fabricated with FBGs embedded. Stress tensile, bending, and dynamic strain tests were performed. The experimental work proved that the FBG sensors have a good level of accuracy in measuring the static response of the tested composite coupons (down to submicrostrain levels), the capability to detect and monitor dynamic loads, and the ability to detect defects in composites by a variety of methods including monitoring the decay time under different dynamic loading conditions. In addition to quasi-static and dynamic load monitoring, the

  9. Polymer sol-gel composite inverse opal structures. (United States)

    Zhang, Xiaoran; Blanchard, G J


    We report on the formation of composite inverse opal structures where the matrix used to form the inverse opal contains both silica, formed using sol-gel chemistry, and poly(ethylene glycol), PEG. We find that the morphology of the inverse opal structure depends on both the amount of PEG incorporated into the matrix and its molecular weight. The extent of organization in the inverse opal structure, which is characterized by scanning electron microscopy and optical reflectance data, is mediated by the chemical bonding interactions between the silica and PEG constituents in the hybrid matrix. Both polymer chain terminus Si-O-C bonding and hydrogen bonding between the polymer backbone oxygens and silanol functionalities can contribute, with the polymer mediating the extent to which Si-O-Si bonds can form within the silica regions of the matrix due to hydrogen-bonding interactions.

  10. Trade study plan for Graphite Composite Primary Structure (GCPS) (United States)

    Greenberg, H. S.


    This TA 2 document (with support from TA 1) describes the trade study plan that will identify the most suitable structural configuration for an SSTO winged vehicle capable of delivering 25,000 lbs to a 220 nm circular orbit at 51.6 degree inclination For this most suitable configuration the structural attachment of the wing, and the most suitable GCPS composite materials for intertank, wing, tail and thrust structure are identified. This trade study analysis uses extensive information derived in the TA 1 trade study plan and is identified within the study plan. In view of this, for convenience, the TA 1 study plan is included as an appendix to this document.

  11. Structural Acoustic Response of Shape Memory Alloy Hybrid Composite Panels (United States)

    Turner, Travis L.


    A method has been developed to predict the structural acoustic response of shape memory alloy hybrid composite panels subjected to acoustic excitation. The panel is modeled by a finite element analysis and the radiated field is predicted using Rayleigh's integral. Transmission loss predictions for the case of an aluminum panel excited by a harmonic acoustic pressure are shown to compare very well with a classical analysis. Predictions of the normal velocity response and transmitted acoustic pressure for a clamped aluminum panel show excellent agreement with experimental measurements. Predicted transmission loss performance for a composite panel with and without shape memory alloy reinforcement are also presented. The preliminary results demonstrate that the transmission loss can be significantly increased with shape memory alloy reinforcement.

  12. How Muscle Structure and Composition Influence Meat and Flesh Quality

    Directory of Open Access Journals (Sweden)

    Anne Listrat


    Full Text Available Skeletal muscle consists of several tissues, such as muscle fibers and connective and adipose tissues. This review aims to describe the features of these various muscle components and their relationships with the technological, nutritional, and sensory properties of meat/flesh from different livestock and fish species. Thus, the contractile and metabolic types, size and number of muscle fibers, the content, composition and distribution of the connective tissue, and the content and lipid composition of intramuscular fat play a role in the determination of meat/flesh appearance, color, tenderness, juiciness, flavor, and technological value. Interestingly, the biochemical and structural characteristics of muscle fibers, intramuscular connective tissue, and intramuscular fat appear to play independent role, which suggests that the properties of these various muscle components can be independently modulated by genetics or environmental factors to achieve production efficiency and improve meat/flesh quality.

  13. Structural and Compositional Transformations of Biomass Chars during Fast Pyrolysis

    DEFF Research Database (Denmark)

    Trubetskaya, Anna; Steibel, Markus; Spliethoff, Hartmut

    In this work the physical and chemical transformations of biomass chars during fast pyrolysis, considered as a 2nd stage of combustion, has been investigated. Seven biomasses containing different amount of ash and organic components were reacted at up to 1673 K with high heating rates in a wire......-mesh reactor and the resulting chars were retrieved. In order to obtain information on the structural and compositional transformations of the biomass chars, samples were subjected to elemental analysis, scanning electron microcopy with EDX and Raman spectrometry. The results show that there are significant...... changes in both the organic and inorganic constituents of the chars.Under high heating rates (> 100 K/s) char particles underwent different types of melting and pores of different size were developed in dependency on the temperature and biomass composition. The Si-rich rice husks char did not show any...

  14. Structural mechanics and helical geometry of thin elastic composites. (United States)

    Wada, Hirofumi


    Helices are ubiquitous in nature, and helical shape transition is often observed in residually stressed bodies, such as composites, wherein materials with different mechanical properties are glued firmly together to form a whole body. Inspired by a variety of biological examples, the basic physical mechanism responsible for the emergence of twisting and bending in such thin composite structures has been extensively studied. Here, we propose a simplified analytical model wherein a slender membrane tube undergoes a helical transition driven by the contraction of an elastic ribbon bound to the membrane surface. We analytically predict the curvature and twist of an emergent helix as functions of differential strains and elastic moduli, which are confirmed by our numerical simulations. Our results may help understand shapes observed in different biological systems, such as spiral bacteria, and could be applied to novel designs of soft machines and robots.

  15. Structure of Al-CF composites obtained by infiltration methods

    Directory of Open Access Journals (Sweden)

    A. Dolata-Grosz


    Full Text Available The structure of the composites obtained in infiltration processes 2D and 3D carbon preform by liquid Al alloy have been presented in thispaper. An aluminum alloy with silicon and manganese AlSi9Mn (trimal 37-TR37 was applied in the researches. As the reinforcementused carbon perform prepared with various protective barriers such as the nickel coating, the coating of silicon carbide and pyrolyticcarbon coating. Carbon preforms was prepared at the Institute for Lightweight Structures and Polymer Technology (ILK TU Dresden andat the Institute of Technology and Ceramic Systems (Fraunhofer-IKTS. The process of infiltration of carbon perform by liquid aluminiumalloy was carried out using a pressure-vacuum infiltration on the Degussa press and gas-pressure infiltration (GPI in an autoclavedesigned and built at the Department of Materials Technology at the Silesian University of Technology. The obtained composites werecharacterized by a regular shape, with no surface casting defects. The best connection of components was observed in AlSi9Mn/Cf(Nicomposite, obtained by gas-pressure infiltration method (GPI. On metallographic specimens, good interface between fibres and thealuminium matrix were observed. The obtained research results justify the application of nickel coatings on the fibres. During the failurecrack propagated across fiber. There was no presence of aluminum carbide on the fiber-matrix. It can be assumed that the composite willbe characterized by the good mechanical properties. However, this requires further experimental verification planned in the next stage of research, in the project realized within the DFG program: "3D textile reinforced aluminium matrix composites for complex loadingsituations in lightweight automobile and machine parts".

  16. Structural, spectral and dielectric properties of piezoelectric-piezomagnetic composites

    Energy Technology Data Exchange (ETDEWEB)

    Hemeda, O.M., E-mail: [Physics Department, Faculty of Science, Taif University, Al-Hawiah, P.O. Box 888, Taif 21974 (Saudi Arabia); Physics Department, Faculty of Science, Tanta University (Egypt); Tawfik, A.; Amer, M.A. [Physics Department, Faculty of Science, Tanta University (Egypt); Kamal, B.M.; El Refaay, D.E. [Physics Department, Faculty of Science, Suez Canal University (Egypt)


    Composite materials of spinel ferrite (SF) NiZnFe{sub 2}O{sub 4} (NZF) and barium titanate (BT) BaTiO{sub 3} were prepared by double sintering ceramic technique. X-ray diffraction patterns for the composite system (1-x) NZF+x BT, showed the presence of mainly of 2 phases, hence confirming the successful preparation of the composite. Some structural and microstructural parameters like porosity, X-ray density, particle size and lattice constant were deduced from the analysis of X-ray data for both phases. Scan electron microscope (SEM) analysis shows nearly a homogeneous microstructure with good dispersion of BT grains as well as the presence of some pores. There was also an enlargement of BT grains with increasing its content. Infra red (IR) spectra of the composite system indicate that BT content affects the intermolecular character of the SF phase. A rise in the dielectric constant occurred at high temperature which was attributed to the effect of space change resulting from the increase of the change carriers in the paramagnetic region. The dielectric loss (tan {delta}) decreased by increasing BT content. - Highlights: Black-Right-Pointing-Pointer Double phase NZF-BT composite has a high magnetoelectric coefficient compared with other materials. Black-Right-Pointing-Pointer This makes it strongly candidates for electromagnetic wave sensors. Black-Right-Pointing-Pointer Addition of BT phase enhance dielectric constant which make it very useful for capacitor industry. Black-Right-Pointing-Pointer Ni ferrite shifts the transition temperature of BT from 120 Degree-Sign C near room temperature. Black-Right-Pointing-Pointer Decrease of dielectric loss which supply with good material with law eddy current loss for cores of t ransformers at microwave frequency.

  17. Surface flow structure of the Gulf Stream from composite imagery and satellite-tracked drifters

    Directory of Open Access Journals (Sweden)

    C. P. Mullen


    Full Text Available A unique set of coutemporaneous satellite-tracked drifters and five-day composite Advanced Very High Resolution Radionmeter (AVHRR satellite imagery of the North Atlantic has been analyzed to examine the surface flow structure of the Gulf Stream. The study region was divided into two sections, greater than 37° N and less than 37° N, in order to answer the question of geographic variability. Fractal and spectral analyses methods were applied to the data. Fractal analysis of the Lagrangian trajectories showed a fractal dimension of 1.21 + 0.02 with a scaling range of 83 - 343 km. The fractal dimension of the temperature fronts of the composite imagery is similar for the two regions with D = 1.11 + 0.01 over a scaling range of 4 - 44 km. Spectral analysis also reports a fairly consistent value for the spectral slope and its scaling range. Therefore, we conclude there is no geographic variability in the data set. A suitable scaling range for this contemporaneous data set is 80 - 200 km which is consistent with the expected physical conditions in the region. Finally, we address the idea of using five-day composite imagery to infer the surface flow of the Gulf Stream. Close analyses of the composite thermal fronts and the Lagrangian drifter trajectories show that the former is not a good indicator of the latter.

  18. Antwerp Advanced Study Institute on Electronic Structure, Dynamics and Quantum Structural Properties of Condensed Matter

    CERN Document Server

    Camp, Piet


    The 1984 Advanced Study Institute on "Electronic Structure, Dynamics and Quantum Structural Properties of Condensed Matter" took place at the Corsendonk Conference Center, close to the City of Antwerpen, from July 16 till 27, 1984. This NATO Advanced Study Institute was motivated by the research in my Institute, where, in 1971, a project was started on "ab-initio" phonon calculations in Silicon. I~ is my pleasure to thank several instances and people who made this ASI possible. First of all, the sponsor of the Institute, the NATO Scientific Committee. Next, the co-sponsors: Agfa-Gevaert, Bell Telephone Mfg. Co. N.V., C & A, Esso Belgium·, CDC Belgium, Janssens Pharmaceutica, Kredietbank and the Scientific Office of the U.S. Army. Special thanks are due to Dr. P. Van Camp and Drs. H. Nachtegaele, who, over several months, prepared the practical aspects of the ASI with the secretarial help of Mrs. R.-M. Vandekerkhof. I also like to. thank Mrs. M. Cuyvers who prepared and organized the subject and material ...

  19. Radiological study on newly developed composite corn advance lines in Malaysia (United States)

    Adekunle Olatunji, Michael; Bemigho Uwatse, Onosohwo; Uddin Khandaker, Mayeen; Amin, Y. M.; Faruq, G.


    Owing to population growth, there has been high demand for food across the world, and hence, different agricultural activities such as use of phosphate fertilizers, recycling of organic matters, etc, have been deployed to increase crop yields. In Malaysia, a total of nine composite corn advance lines have been developed at the Institute of Biological Sciences, University of Malaya and are being grown under different conditions with a bid to meet the average daily human need for energy and fiber intake. To this end, the knowledge of radioactivity levels in these corn advance lines are of paramount importance for the estimation of possible radiological hazards due to its consumption. Hence, the radioactivity concentrations of 226Ra, 228Ra and 40K in the corn have been determined using HPGe γ-ray spectrometry. The activity concentrations in the corn ranged from 0.05 to 19.18 Bq kg-1 for 226Ra, from 0.10 to 3.22 Bq kg-1 for 228Ra and from 26.4 to 129 Bq kg-1 for 40K. In order to ascertain the radiological safety of the population regarding maize consumption, the daily intakes of these radionuclides as well as the annual effective dose were estimated. The total effective dose obtained due to the ingestion of radionuclides via maize consumption is 15.39 μSv y-1, which is less than the international recommendations.

  20. Melt Infiltrated Ceramic Matrix Composites for Shrouds and Combustor Liners of Advanced Industrial Gas Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Corman; Krishan Luthra; Jill Jonkowski; Joseph Mavec; Paul Bakke; Debbie Haught; Merrill Smith


    This report covers work performed under the Advanced Materials for Advanced Industrial Gas Turbines (AMAIGT) program by GE Global Research and its collaborators from 2000 through 2010. A first stage shroud for a 7FA-class gas turbine engine utilizing HiPerComp{reg_sign}* ceramic matrix composite (CMC) material was developed. The design, fabrication, rig testing and engine testing of this shroud system are described. Through two field engine tests, the latter of which is still in progress at a Jacksonville Electric Authority generating station, the robustness of the CMC material and the shroud system in general were demonstrated, with shrouds having accumulated nearly 7,000 hours of field engine testing at the conclusion of the program. During the latter test the engine performance benefits from utilizing CMC shrouds were verified. Similar development of a CMC combustor liner design for a 7FA-class engine is also described. The feasibility of using the HiPerComp{reg_sign} CMC material for combustor liner applications was demonstrated in a Solar Turbines Ceramic Stationary Gas Turbine (CSGT) engine test where the liner performed without incident for 12,822 hours. The deposition processes for applying environmental barrier coatings to the CMC components were also developed, and the performance of the coatings in the rig and engine tests is described.


    Directory of Open Access Journals (Sweden)

    Andrew R. Rutledge


    Full Text Available The production of microporous carbon foams from renewable starch microcellular foam-fiber (SMCF-Fiber composites is described. Carbon foams are used in applications such as thermal insulation, battery electrodes, filters, fuel cells, and medical devices. SMCF-Fiber compos-ites were created from an aquagel. The water in the aquagel was exchanged with ethanol and then dried and carbonized. Higher amylose content starches and fiber contents of up to 4% improved the processability of the foam. The SMCF structure revealed agglomerates of swollen starch granules connected by a web of starch with pores in the 50-200 nanometer range. Heating the SMCF-fiber in a nitrogen atmosphere to temperatures between 350-700˚C produced carbon foams with a three-dimensional closed cell foam structure with cell diameters around 50 microns and pore walls around 1-3 microns. The stress versus strain compression data for carbonized samples displayed a linear elastic region and a plateau indicative of brittle crushing, typical of an elastic-brittle foam. The carbon foam products from these renew-able precursors are promising carbon structures with moderate strength and low density.

  2. Buckling and Post-buckling Performance of Advanced Composite Stiffened Panel Under Compression

    Directory of Open Access Journals (Sweden)

    ZHANG Haoyu


    Full Text Available The axial compressive experiment was conducted on the domestic advanced composite stiffened panel, and its buckling and post-buckling performance was analyzed by monitoring strain and out-of-plane displacement of typical positions. The initial buckling load and buckling mode of panels were calculated by engineering methods to direct the follow-up axial compressive experiment. The experimental results show that the buckling patterns are mainly local buckling of panels between stiffeners, the second buckling of few positions of panels and cylindrical buckling of all 4 stiffeners successively; after local buckling of panels, part of load bearded by panels before is transferred to stiffeners and then stiffeners become the main bearing part; after fracture failure of stiffeners, the specimen is destroyed rapidly; the average value of failure load is 482.67 kN, which is 2.37 times of 204 kN of the average value of buckling load; the composite stiffened panel can bear more load after buckling.

  3. Preparing GMAT for Operational Maneuver Planning of the Advanced Composition Explorer (ACE) (United States)

    Qureshi, Rizwan Hamid; Hughes, Steven P.


    The General Mission Analysis Tool (GMAT) is an open-source space mission design, analysis and trajectory optimization tool. GMAT is developed by a team of NASA, private industry, public and private contributors. GMAT is designed to model, optimize and estimate spacecraft trajectories in flight regimes ranging from low Earth orbit to lunar applications, interplanetary trajectories and other deep space missions. GMAT has also been flight qualified to support operational maneuver planning for the Advanced Composition Explorer (ACE) mission. ACE was launched in August, 1997 and is orbiting the Sun-Earth L1 libration point. The primary science objective of ACE is to study the composition of both the solar wind and the galactic cosmic rays. Operational orbit determination, maneuver operations and product generation for ACE are conducted by NASA Goddard Space Flight Center (GSFC) Flight Dynamics Facility (FDF). This paper discusses the entire engineering lifecycle and major operational certification milestones that GMAT successfully completed to obtain operational certification for the ACE mission. Operational certification milestones such as gathering of the requirements for ACE operational maneuver planning, gap analysis, test plans and procedures development, system design, pre-shadow operations, training to FDF ACE maneuver planners, shadow operations, Test Readiness Review (TRR) and finally Operational Readiness Review (ORR) are discussed. These efforts have demonstrated that GMAT is flight quality software ready to support ACE mission operations in the FDF.

  4. Impact localization for a composite plate using the spatial focusing properties of advanced signal processing techniques

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hyunjo; Cho, Sungjong [Wonkwang Univ., Iksan (Korea, Republic of)


    A structural health monitoring technique for locating impact position in a composite plate is presented in this paper. The method employs a single sensor and spatial focusing properties of time reversal(TR) and inverse filtering(IF). We first examine the spatial focusing efficiency of both approaches at the impact position and its surroundings through impact experiments. The imaging results of impact localization show that the impact location can be accurately estimated in any position of the plate. Compared to existing techniques for locating impact or acoustic emission source, the proposed method has the benefits of using a single sensor and not requiring knowledge of anisotropic material properties and geometry of structures. Furthermore, it does not depend on a particular mode of dispersive Lamb waves that is frequently used in other ultrasonic testing of plate like structures.

  5. Structural and functional polymer-matrix composites for electromagnetic applications (United States)

    Wu, Junhua

    This dissertation addresses the science and technology of functional and structural polymer-matrix composite materials for electromagnetic applications, which include electromagnetic interference (EMI) shielding and low observability (Stealth). The structural composites are continuous carbon fiber epoxy-matrix composites, which are widely used for airframes. The functional composites are composites with discontinuous fillers and in both bulk and coating forms. Through composite structure variation, attractive electromagnetic properties have been achieved. With no degradation of the tensile strength or modulus, the shielding effectiveness of the structural composites has been improved by enhancing multiple reflections through light activation of the carbon fiber. The multiple reflections loss of the electromagnetic wave increases from 1.1 to 10.2 dB at 1.0 GHz due to the activation. Such a large effect of multiple reflections has not been previously reported in any material. The observability of these composites has been lowered by decreasing the electrical conductivity (and hence decreasing the reflection loss) through carbon fiber coating. The incorporation of mumetal, a magnetic alloy particulate filler (28-40 mum size), in a latex paint has been found to be effective for enhancing the shielding only if the electrical resistivity of the resulting composite coating is below 10, as rendered by a conductive particulate filler, such as nickel flake (14-20 mum size). This effectiveness (39 dB at 1.0 GHz) is attributed to the absorption of the electromagnetic wave by the mumetal and the nickel flake, with the high conductivity rendered by the presence of the nickel flake resulting in a relatively high reflection loss of 15.5 dB. Without the nickel flake, the mumetal gives only 3 dB of shielding and 1.5 dB of reflection loss at 1.0 GHz. Nickel powder (0.3-0.5 mum size) has been found to be an effective filler for improving the shielding of polyethersulfone (PES

  6. A Damage Model for the Simulation of Delamination in Advanced Composites under Variable-Mode Loading (United States)

    Turon, A.; Camanho, P. P.; Costa, J.; Davila, C. G.


    A thermodynamically consistent damage model is proposed for the simulation of progressive delamination in composite materials under variable-mode ratio. The model is formulated in the context of Damage Mechanics. A novel constitutive equation is developed to model the initiation and propagation of delamination. A delamination initiation criterion is proposed to assure that the formulation can account for changes in the loading mode in a thermodynamically consistent way. The formulation accounts for crack closure effects to avoid interfacial penetration of two adjacent layers after complete decohesion. The model is implemented in a finite element formulation, and the numerical predictions are compared with experimental results obtained in both composite test specimens and structural components.

  7. Measuring Moisture Levels in Graphite Epoxy Composite Sandwich Structures (United States)

    Nurge, Mark; Youngquist, Robert; Starr, Stanley


    Graphite epoxy composite (GEC) materials are used in the construction of rocket fairings, nose cones, interstage adapters, and heat shields due to their high strength and light weight. However, they absorb moisture depending on the environmental conditions they are exposed to prior to launch. Too much moisture absorption can become a problem when temperature and pressure changes experienced during launch cause the water to vaporize. The rapid state change of the water can result in structural failure of the material. In addition, heat and moisture combine to weaken GEC structures. Diffusion models that predict the total accumulated moisture content based on the environmental conditions are one accepted method of determining if the material strength has been reduced to an unacceptable level. However, there currently doesn t exist any field measurement technique to estimate the actual moisture content of a composite structure. A multi-layer diffusion model was constructed with Mathematica to predict moisture absorption and desorption from the GEC sandwich structure. This model is used in conjunction with relative humidity/temperature sensors both on the inside and outside of the material to determine the moisture levels in the structure. Because the core materials have much higher diffusivity than the face sheets, a single relative humidity measurement will accurately reflect the moisture levels in the core. When combined with an external relative humidity measurement, the model can be used to determine the moisture levels in the face sheets. Since diffusion is temperaturedependent, the temperature measurements are used to determine the diffusivity of the face sheets for the model computations.

  8. Innovative design of composite structures: The use of curvilinear fiber format in composite structure design (United States)

    Hyer, M. W.; Charette, R. F.


    The gains in structural efficiency are investigated that can be achieved by aligning the fibers in some or all of the layers in a laminate with the principal stress directions in those layers. The name curvilinear fiber format is given to this idea. The problem studied is a plate with a central circular hole subjected to a uniaxial tensile load. An iteration scheme is used to find the fiber directions at each point in the laminate. Two failure criteria are used to evaluate the tensile load capacity of the plates with a curvilinear format, and for comparison, counterpart plates with a conventional straightline fiber format. The curvilinear designs for improved tensile capacity are then checked for buckling resistance. It is concluded that gains in efficiency can be realized with the curvilinear format.

  9. Exploring hierarchical FeS2/C composite nanotubes arrays as advanced cathode for lithium ion batteries (United States)

    Pan, G. X.; Cao, F.; Xia, X. H.; Zhang, Y. J.


    Rational construction of advanced FeS2 cathode is one of research hotspots, and of great importance for developing high-performance lithium ion batteries (LIBs). Herein we report a facile hydrolysis-sulfurization method for fabrication of FeS2/C nanotubes arrays with the help of sacrificial Co2(OH)2CO3 nanowires template and glucose carbonization. Self-supported FeS2/C nanotubes consist of interconnected nanoburrs of 5-20 nm, and show hierarchical porous structure. The FeS2/C nanotubes arrays are demonstrated with enhanced cycling life and noticeable high-rate capability with capacities ranging from 735 mAh g-1 at 0.25 C to 482 mAh g-1 at 1.5 C, superior to those FeS2 counterparts in the literature. The composite nanotubes arrays architecture plays positive roles in the electrochemical enhancement due to combined advantages of large electrode-electrolyte contact area, good strain accommodation, improved electrical conductivity, and enhanced structural stability.


    Directory of Open Access Journals (Sweden)

    F. G. Lovshenko


    Full Text Available The paper presents investigation results pertaining to  ascertainment of formation regularities of phase composition and structure during mechanical alloying of binary aluminium composites/substances. The invetigations have been executed while applying a wide range of methods, devices and equipment used in modern material science. The obtained data complement each other. It has been established that presence of oxide and hydro-oxide films on aluminium powder  and introduction of surface-active substance in the composite have significant effect on mechanically and thermally activated phase transformations and properties of semi-finished products.  Higher fatty acids have been used as a surface active substance.The mechanism of mechanically activated solid solution formation has been identified. Its essence is  a formation of  specific quasi-solutions at the initial stage of processing. Mechanical and chemical interaction between components during formation of other phases has taken place along with dissolution  in aluminium while processing powder composites. Granule basis is formed according to the dynamic recrystallization mechanism and possess submicrocrystal structural type with the granule dimension basis less than 100 nm and the grains are divided in block size of not more than 20 nm with oxide inclusions of 10–20 nm size.All the compounds  with the addition of  surface-active substances including aluminium powder without alloying elements obtained by processing in mechanic reactor are disperse hardened. In some cases disperse hardening is accompanied by dispersive and solid solution hardnening process. Complex hardening predetermines a high temperature of recrystallization in mechanically alloyed compounds,  its value exceeds 400 °C.

  11. Dynamics Assessment of Advanced Single-Phase PLL Structures

    DEFF Research Database (Denmark)

    Golestan, Saeed; Monfarad, Mohammad; Freijedo, Francisco D.;


    , and desired performance under frequency-varying and harmonically distorted grid conditions. Despite the wide acceptance and use of these two advanced PLLs, no comprehensive design guidelines to fine-tune their parameters have been reported yet. Through a detailed mathematical analysis it is shown...

  12. Investigation of Structural Properties of Carbon-Epoxy Composites Using Embedded Fiber-Optic Bragg Gratings (United States)

    Osei, Albert J.


    coupled into the optical fiber sensor, a reflection peak will be obtained centered around a wavelength called Bragg-wavelength. The Bragg-wavelength depends on the refractive index and the period of the grating, which both change due to mechanical and thermal strain applied to the sensor. The shift in the Bragg-wavelength is directly proportional to the strain. Researchers at NASA MSFC are currently developing techniques for using FBGs for monitoring the integrity of advanced structural materials expected to become the mainstay of the current and future generation space structures. Since carbon-epoxy composites are the materials of choice for the current space structures, the initial study is concentrated on this type of composite. The goals of this activity are to use embedded FBG sensors for measuring strain and temperature of composite structures, and to investigate the effects of various parameters such as composite fiber orientation with respect to the optical sensor, unidirectional fiber composite, fabrication process etc., on the optical performance of the sensor. This paper describes an experiment to demonstrate the use of an embedded FBG for measuring strain in a composite material. The performance of the fiber optic sensor is determined by direct comparison with results from more conventional instrumentation.

  13. Certification of Discontinuous Composite Material Forms for Aircraft Structures (United States)

    Arce, Michael Roger

    New, high performance chopped, discontinuous, or short fiber composites (DFCs), DFCs, such as HexMC and Lytex, made by compression molding of randomly oriented pre-impregnated unidirectional tape, can be formed into complex geometry while retaining mechanical properties suitable for structural use. These DFCs provide the performance benefits of Continuous Fiber Composites (CFCs) in form factors that were previously unavailable. These materials demonstrate some notably different properties from continuous fiber composites, especially with respect to damage tolerance and failure behavior. These behaviors are not very well understood, and fundamental research efforts are ongoing to better characterize the material and to ease certification for future uses. Despite this, these new DFCs show such promise that they are already in service in the aerospace industry, for instance in the Boeing 787. Unfortunately, the relative novelty of these parts means that they needed to be certified by “point design”, an excess of physical testing, rather than by a mix of physical testing and finite element analysis, which would be the case for CFCs or metals. In this study, one particular approach to characterizing both linear-elastic and failure behaviors are considered. The Stochastic Laminate Analogy, which represents a novel approach to modeling DFCs, and its combination with a Ply Discount scheme. Owing to limited available computational resources, only preliminary results are available, but those results are quite promising and warrant further investigation.

  14. Possible Internal Structures and Compositions of Proxima Centauri b (United States)

    Brugger, B.; Mousis, O.; Deleuil, M.; Lunine, J. I.


    We explore the possible interiors of Proxima Centauri b, assuming that the planet belongs to the class of dense solid planets (rocky with possible addition of water) and derive the corresponding radii. To do so, we use an internal structure model that computes the radius of the planet along with the locations of the different layers of materials, assuming that its mass and bulk composition are known. Lacking detailed elementary abundances of the host star to constrain the planet’s composition, we base our model on solar system values. We restrained the simulations to the case of solid planets without massive atmospheres. With these assumptions, the possible radius of Proxima Centauri b spans the 0.94-1.40 R ⊕ range. The minimum value is obtained considering a 1.10 M ⊕ Mercury-like planet with a 65% core mass fraction, whereas the highest radius is reached for 1.46 M ⊕ with 50% water in mass, constituting an ocean planet. Although this range of radii still allows for very different planet compositions, it helps to characterize many aspects of Proxima Centauri b, such as the formation conditions of the system or the current amount of water on the planet. This work can also help rule out future measurements of the planet’s radius that would be physically incompatible with a solid planetary body.

  15. Structure recognition from high resolution images of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela; Perciano, Talita; Krishnan, Harinarayan; Loring, Burlen; Bale, Hrishikesh; Parkinson, Dilworth; Sethian, James


    Fibers provide exceptional strength-to-weight ratio capabilities when woven into ceramic composites, transforming them into materials with exceptional resistance to high temperature, and high strength combined with improved fracture toughness. Microcracks are inevitable when the material is under strain, which can be imaged using synchrotron X-ray computed micro-tomography (mu-CT) for assessment of material mechanical toughness variation. An important part of this analysis is to recognize fibrillar features. This paper presents algorithms for detecting and quantifying composite cracks and fiber breaks from high-resolution image stacks. First, we propose recognition algorithms to identify the different structures of the composite, including matrix cracks and fibers breaks. Second, we introduce our package F3D for fast filtering of large 3D imagery, implemented in OpenCL to take advantage of graphic cards. Results show that our algorithms automatically identify micro-damage and that the GPU-based implementation introduced here takes minutes, being 17x faster than similar tools on a typical image file.

  16. Crystal structure, magnetic properties and advances in hexaferrites: A brief review (United States)

    Jotania, Rajshree


    Hexaferrites are hard magnetic materials and specifically ferri-magnetic oxides with hexagonal magnetoplumbite type crystallographic structure. Hexagonal ferrites are used as permanent magnets, high-density perpendicular and magneto-optical recording media, and microwave devices like resonance isolators, filters, circulators, phase shifters because of their high magnetic permeability, high electrical resistivity and moderable permittivity. In addition to these; hexagonal ferrites have excellent chemical stability, mechanical hardness and low eddy current loss at high frequencies. The preparation of hexaferrites is a complicated process. Various experimental techniques like standard ceramic techniques, solvent free synthesis route, co precipitation, salt-melt, ion exchange, sol-gel, citrate synthesis, hydrothermal synthesis, spray drying, water-in-oil microemulsion, reverse micelle etc are used to prepare hexaferrite materials. Structural, dielectric and magnetic properties, crystallite size of hexaferrites depend upon nature of substituted ions, method of preparation, sintering temperature and time. The recent interest is nanotechnology, the development of hexaferrite fibres and composites with carbon nano tubes (CNT). Magnetic properties of some doped and un-doped hexaferrites are discussed here. Recent advances in hexaferrites also highlighted in present paper.

  17. Composition and structure of Ti-C/DLC graded composite films

    Institute of Scientific and Technical Information of China (English)

    孙明仁; 夏立芳


    The Ti-C→DLC gradient composite films were characterized systematically.The elemental depth profile and elemental chemical state evolution were determined by X-ray photoelectron spectroscopy (XPS).The transmission electron microscope (TEM) and high-resolution transmission electron microscopy (HRTEM) were used to study the structure of interfacial zone between DLC film and Ti-C layers.Results show that there are composition transition zone between DLC film and either Ti-C layer or steel substrate on condition that pre-deposited Ti layers on the steel substrate then plasma based bias deposited DLC films.In Ti-C graded layer,the chemical state of titanium and carbon are changed gradually.The structures of zone in Ti-C layer near the DLC film is consisted of random oriented nanocrystallines TiC dispersed in amorphous DLC matrix.The structure of the zone between DLC film and Ti-C graded layer is gradually changed too.

  18. Open-structure composite mirrors for the Cherenkov Telescope Array

    CERN Document Server

    Dyrda, Michal; Niemiec, Jacek; Stodulski, Marek


    The Cherenkov Telescope Array (CTA) Observatory for high-energy gamma-ray astronomy will comprise several tens of imaging atmospheric Cherenkov telescopes (IACTs) of different size with a total reflective area of about 10,000 m$^2$. Here we present a new technology for the production of IACT mirrors that has been developed in the Institute of Nuclear Physics PAS in Krakow, Poland. An open-structure composite mirror consists of a rigid flat sandwich support structure and cast-in-mould spherical epoxy resin layer. To this layer a thin glass sheet complete with optical coating is cold-slumped to provide the spherical reflective layer of the mirror. The main components of the sandwich support structure are two flat float glass panels inter spaced with V-shape aluminum spacers of equal length. The sandwich support structure is open, thus enabling good cooling and ventilation of the mirror. A special arrangement of the aluminum spacers also prohibits water being trapped inside. The open-structure technology thus re...


    Institute of Scientific and Technical Information of China (English)

    Xian-feng Li; Chang-fa Xiao


    Composite polyurethane (PU)-SiO2 hollow fiber membranes were successfully prepared via optimizing the technique of dry-jet wet spinning, and their pressure-responsibilities were confirmed by the relationships of pure water fluxtransmembrane pressure (PWF-TP) for the first time. The origin for this phenomenon was analyzed on the basis of membrane structure and material characteristics. The effects of SiO2 content on the structure and properties of membrane were investigated. The experimental results indicated that SiO2 in membrane created a great many interfacial micro-voids and played an important role in pressure-responsibility, PWF and rejection of membrane: with the increase of SiO2 content, the ability of membrane recovery weakened, PWF increased, and rejection decreased slightly.

  20. Laser Surface Preparation and Bonding of Aerospace Structural Composites (United States)

    Belcher, M. A.; Wohl, C. J.; Hopkins, J. W.; Connell, J. W.


    Adhesive bonds are critical to the integrity of built-up structures. Disbonds can often be detected but the strength of adhesion between surfaces in contact is not obtainable without destructive testing. Typically the number one problem in a bonded structure is surface contamination, and by extension, surface preparation. Standard surface preparation techniques, including grit blasting, manual abrasion, and peel ply, are not ideal because of variations in their application. Etching of carbon fiber reinforced plastic (CFRP) panels using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser appears to be a highly precise and promising way to both clean a composite surface prior to bonding and provide a bond-promoting patterned surface akin to peel ply without the inherent drawbacks from the same (i.e., debris and curvature). CFRP surfaces prepared using laser patterns conducive to adhesive bonding were compared to typical prebonding surface treatments through optical microscopy, contact angle goniometry, and post-bonding mechanical testing.

  1. Advanced vectorial simulation of VCSELs with nano structures invited paper

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper


    The single-mode properties and design issues of three vertical-cavity surface-emitting laser (VCSEL) structures incorporating nano structures are rigorously investigated. Nano structuring enables to deliver selective pumping or loss to the fundamental mode as well as stabilizing the output...... polarization state. Comparison of three vectorial simulation methods reveals that the modal expansion method is suitable for treating the nano structured VCSEL designs....

  2. Structure and antibacterial properties of polyethylene/organo-vermiculite composites (United States)

    Hundáková, Marianna; Tokarský, Jonáš; Valášková, Marta; Slobodian, Petr; Pazdziora, Erich; Kimmer, Dušan


    Vermiculite (VER) was modified by cation exchange with hexadecyltrimethylammonium (HDTMA+) bromide in three concentrations and used as organo-VER clay mineral nanofillers (denoted as HDTMA+1-VER, HDTMA+2-VER, and HDTMA+3-VER) in polyethylene (PE). PE/organo-VER composites were prepared via a melt compounding technique and pressed into thin plates. The organo-VER nanofillers and composite plates were characterized by X-ray diffraction analysis which in combination with molecular modeling confirmed the intercalation of HDTMA+ molecules. It was found that alkyl tails of HDTMA+ molecules create a non-polar, water-free area which may help the PE chains to enter the VER interlayer space. The nanocomposite structure was confirmed for PE/HDTMA+3-VER. PE/organo-VER composites were also studied by scanning electron microscopy and light microscopy and by creep testing. Antibacterial activity of powder organo-VER nanofillers was tested on Gram-positive (G+) (Staphylococcus aureus, Enterococcus faecalis) and Gram-negative (G-) (Escherichia coli) bacterial strains. The most sensitive G+ bacteria responded by stopping their bacterial growth after 24 h with a minimum inhibitory concentration (MIC) 0.014% (w/v) at all samples. Growth of G- bacteria was inhibited after 24 h with higher MIC value 0.041-10% (w/v) in relation to the content of HDTMA+ in samples. The surfaces of PE/organo-VER composites are very active against G+ bacterial strain E. faecalis. The number of bacterial colonies forming units (cfu) on surfaces of samples was reduced by approximately several orders. The number of bacterial colonies after 48 h was 0 cfu on the surface of PE/HDTMA+3-VER nanocomposite.

  3. Continuation of tailored composite structures of ordered staple thermoplastic material (United States)

    Santare, Michael H.; Pipes, R. Byron


    The search for the cost effective composite structure has motivated the investigation of several approaches to develop composite structure from innovative material forms. Among the promising approaches is the conversion of a planar sheet to components of complex curvature through sheet forming or stretch forming. In both cases, the potential for material stretch in the fiber direction appears to offer a clear advantage in formability over continuous fiber systems. A framework was established which allows the simulation of the anisotropic mechanisms of deformation of long discontinuous fiber laminates wherein the matrix phase is a viscous fluid. Predictions for the effective viscosities of a hyper-anisotropic medium consisting of collimated, discontinuous fibers suspended in viscous matrix were extended to capture the characteristics of typical polymers including non-Newtonian behavior and temperature dependence. In addition, the influence of fiber misorientation was also modeled by compliance averaging to determine ensemble properties for a given orientation distribution. A design tool is presented for predicting the effect of material heterogeneity on the performance of curved composite beams such as those used in aircraft fuselage structures. Material heterogeneity can be induced during manufacturing processes such as sheet forming and stretch forming of thermoplastic composites. This heterogeneity can be introduced in the form of fiber realignment and spreading during the manufacturing process causing radial and tangential gradients in material properties. Two analysis procedures are used to solve the beam problems. The first method uses separate two-dimensional elasticity solutions for the stresses in the flange and web sections of the beam. The separate solutions are coupled by requiring that forces and displacements match section boundaries. The second method uses an approximate Rayleigh-Ritz technique to find the solutions for more complex beams. Analyses

  4. Flux balance analysis of plant metabolism: the effect of biomass composition and model structure on model predictions

    Directory of Open Access Journals (Sweden)

    Huili eYuan


    Full Text Available The biomass composition represented in constraint-based metabolic models is a key component for predicting cellular metabolism using flux balance analysis (FBA. Despite major advances in analytical technologies, it is often challenging to obtain a detailed composition of all major biomass components experimentally. Studies examining the influence of the biomass composition on the predictions of metabolic models have so far mostly been done on models of microorganisms. Little is known about the impact of varying biomass composition on flux prediction in FBA models of plants, whose metabolism is very versatile and complex because of the presence of multiple subcellular compartments. Also, the published metabolic models of plants differ in size and complexity. In this study, we examined the sensitivity of the predicted fluxes of plant metabolic models to biomass composition and model structure. These questions were addressed by evaluating the sensitivity of predictions of growth rates and central carbon metabolic fluxes to varying biomass compositions in three different genome-/large-scale metabolic models of Arabidopsis thaliana. Our results showed that fluxes through the central carbon metabolism were robust to changes in biomass composition. Nevertheless, comparisons between the predictions from three models using identical modelling constraints and objective function showed that model predictions were sensitive to the structure of the models, highlighting large discrepancies between the published models.

  5. Self-Healing Concept for Damaged Composite Structure of Automobile Bonnet

    Directory of Open Access Journals (Sweden)

    Park Hyunbum


    Full Text Available In this work, a structural design and analysis on automobile bonnet using natural flax fiber composite is performed. Through the structural analyses using commercial FEM software, it is confirmed that the designed automobile bonnet using natural composite is acceptable for structural safety. And also, the damage is a critical problem in composites during their service in structural applications. Therefore, study on self-healing concept of bonnet structure was performed.

  6. Structural and electrical measurements of CdZnSe composite

    Indian Academy of Sciences (India)

    V Kishore; Vibhav K Saraswat; N S Saxena; T P Sharma


    The – characterization and the electrical resistivity of selenium rich Se85Cd15–Zn ( = 0, 3, 7, 11 and 15) system at room temperature have been studied. Samples were obtained using melt cooling technique. So prepared samples were then characterized in terms of their crystal structure and lattice parameter using X-ray diffraction method. The materials were found to be polycrystalline in nature, having zinc blend structure over the whole range of zinc concentration. The measurements of – characteristics have been carried out at different temperatures from room to 140°C. The electrical resistivity of the samples with composition at room temperature has been found to vary between maximum 2.7 × 108 m and minimum 7.3 × 105 m and shows a maximum at 3 at. wt.% of Zn. The carrier activation energy of the samples with composition has also been determined and found to vary from 0.026 eV to 0.111 eV.

  7. Optimization Design System for Composite Structures Based on Grid Technology

    Institute of Scientific and Technical Information of China (English)

    CHENG Wen-yuan; CHANG Yan; CUI De-gang; XIE Xiang-hui


    To solve the topology optimization of complicated multi-objective continuous/discrete design variables in aircraft structure design, a Parallel Pareto Genetic Algorithm (PPGA) is presented based on grid platform in this paper. In the algorithm, the commercial finite element analysis (FEA) software is integrated as the calculating tool for analyzing the objective functions and the filter of Pareto solution set based on weight information is introduced to deal with the relationships among all objectives. Grid technology is utilized in PPGA to realize the distributed computations and the user interface is developed to realize the job submission and job management locally/remotely. Taking the aero-elastic tailoring of a composite wing for optimization as an example, a set of Pareto solutions are obtained for the decision-maker. The numerical results show that the aileron reversal problem can be solved by adding the limited skin weight in this system. The algorithm can be used to solve complicated topology optimization for composite structures in engineering and the computation efficiency can be improved greatly by using the grid platform that aggregates numerous idle resources.

  8. Analysis of SMA Hybrid Composite Structures using Commercial Codes (United States)

    Turner, Travis L.; Patel, Hemant D.


    A thermomechanical model for shape memory alloy (SMA) actuators and SMA hybrid composite (SMAHC) structures has been recently implemented in the commercial finite element codes MSC.Nastran and ABAQUS. The model may be easily implemented in any code that has the capability for analysis of laminated composite structures with temperature dependent material properties. The model is also relatively easy to use and requires input of only fundamental engineering properties. A brief description of the model is presented, followed by discussion of implementation and usage in the commercial codes. Results are presented from static and dynamic analysis of SMAHC beams of two types; a beam clamped at each end and a cantilevered beam. Nonlinear static (post-buckling) and random response analyses are demonstrated for the first specimen. Static deflection (shape) control is demonstrated for the cantilevered beam. Approaches for modeling SMAHC material systems with embedded SMA in ribbon and small round wire product forms are demonstrated and compared. The results from the commercial codes are compared to those from a research code as validation of the commercial implementations; excellent correlation is achieved in all cases.

  9. Structure and composition of the continental crust in East China

    Institute of Scientific and Technical Information of China (English)

    高山; 骆庭川; 张本仁; 张宏飞; 韩吟文; 赵志丹; KERN; Hartmut


    Crustal structures of nine broad tectonic units in China, except the Tarim craton, are derived from 18 seismic refraction profiles including 12 geoscience transects. Abundances of 63 major, trace and rare earth elements in the upper crust in East China are estimated. The estimates are based on sampling of 11 451 individual rock samples over an area of 950 000 km~2, from which 905 large composite samples are prepared and analyzed by 13 methods. The middle, lower and total crust compositions of East China are also estimated from studies of exposed crustal cross sections and granulite xenoliths and by correlation of seismic data with lithologies. All the tectonic units except the Tarim craton and the Qinling orogen show a four-layered crustal structure, consisting of the upper, middle, upper lower, and lowermost crusts. P-wave velocities of the bulk lower crust and total crust are 6.8—7.0 and 6.4—6.5 km/s, respectively. They are slower by 0.2—0.4 km/s than the global averages. The bulk lower crust is su

  10. Autonomous stimulus triggered self-healing in smart structural composites (United States)

    Norris, C. J.; White, J. A. P.; McCombe, G.; Chatterjee, P.; Bond, I. P.; Trask, R. S.


    Inspired by the ability of biological systems to sense and autonomously heal damage, this research has successfully demonstrated the first autonomous, stimulus triggered, self-healing system in a structural composite material. Both the sensing and healing mechanisms are reliant on microvascular channels incorporated within a laminated composite material. For the triggering mechanism, a single air filled vessel was pressurized, sealed and monitored. Upon drop weight impact (10 J), delamination and microcrack connectivity between the pressurized vessel and those open to ambient led to a pressure loss which, with the use of a suitable sensor, triggered a pump to deliver a healing agent to the damage zone. Using this autonomous healing approach, near full recovery of post-impact compression strength was achieved (94% on average). A simplified alternative system with healing agent continuously flowing through the vessels, akin to blood flow, was found to offer 100% recovery of the material’s virgin strength. Optical microscopy and ultrasonic C-scanning provided further evidence of large-scale infusion of matrix damage with the healing agent. The successful implementation of this bioinspired technology could substantially enhance the integrity and reliability of aerospace structures, whilst offering benefits through improved performance/weight ratios and extended lifetimes.

  11. Four-dimensional space groups for pedestrians: composite structures. (United States)

    Sun, Junliang; Lee, Stephen; Lin, Jianhua


    Higher-dimensional crystals have been studied for the last thirty years. However, most practicing chemists, materials scientists, and crystallographers continue to eschew the use of higher-dimensional crystallography in their work. Yet it has become increasingly clear in recent years that the number of higher-dimensional systems continues to grow from hundreds to as many as a thousand different compounds. Part of the problem has to do with the somewhat opaque language that has developed over the past decades to describe higher-dimensional systems. This language, while well-suited to the specialist, is too sophisticated for the neophyte wishing to enter the field, and as such can be an impediment. This Focus Review hopes to address this issue. The goal of this article is to show the regular chemist or materials scientist that knowledge of regular 3D crystallography is all that is really necessary to understand 4D crystal systems. To this end, we have couched higher-dimensional composite structures in the language of ordinary 3D crystals. In particular, we developed the principle of complementarity, which allows one to identify correctly 4D space groups solely from examination of the two 3D components that make up a typical 4D composite structure.

  12. Towards composite spheres as building blocks for structured molecules (United States)

    Lee, Lloyd L.; Pellicane, Giuseppe


    In order to design a flexible molecular model that mimics the chemical moieties of a polyatomic molecule, we propose the ‘composite-sphere’ model that can assemble the essential elements to produce the structure of the target molecule. This is likened to the polymerization process where monomers assemble to form the polymer. The assemblage is built into the pair interaction potentials which can ‘react’ (figuratively) with selective pieces into various bonds. In addition, we preserve the spherical symmetries of the individual pair potentials so that the isotropic Ornstein-Zernike equation (OZ) for multi-component mixtures can be used as a theoretical framework. We first test our approach on generating a dumbbell molecule. An equimolar binary mixture of hard spheres and square-well spheres are allowed to react to form a dimer. As the bond length shrinks to zero, we create a site-site model of a Janus-like molecule with a repulsive moiety and an attractive moiety. We employ the zero-separation (ZSEP) closure to solve the OZ equations. The structure and thermodynamic properties are calculated at three isotherms and at several densities and the results are compared with Monte Carlo simulations. The close agreement achieved demonstrates that the ZSEP closure is a reliable theory for this composite-sphere fluid model. Contribution to the George Stell Memorial Issue.

  13. Increased complexity of gene structure and base composition in vertebrates

    Institute of Scientific and Technical Information of China (English)

    Ying Wu; Huizhong Yuan; Shengjun Tan; Jian-Qun Chen; Dacheng Tian; Haiwang Yang


    How the structure and base composition of genes changed with the evolution of vertebrates remains a puzzling question. Here we analyzed 895 orthologous protein-coding genes in six multicellular animals: human, chicken, zebrafish, sea squirt, fruit fly, and worm. Our analyses reveal that many gene regions, particularly intron and 3' UTR, gradually expanded throughout the evolution of vertebrates from their invertebrate ancestors, and that the number of exons per gene increased. Studies based on all protein-coding genes in each genome provide consistent results.We also find that GC-content increased in many gene regions (especially 5' UTR) in the evolution of endotherms, except in coding-exons.Analysis of individual genomes shows that 3′ UTR demonstrated stronger length and CC-content correlation with intron than 5' UTR, and gene with large intron in all six species demonstrated relatively similar GC-content. Our data indicates a great increase in complexity in vertebrate genes and we propose that the requirement for morphological and functional changes is probably the driving force behind the evolution of structure and base composition complexity in multicellular animal genes.

  14. Vibration based structural health monitoring of composite skin-stiffener structures

    NARCIS (Netherlands)

    Ooijevaar, T.H.


    Composite materials combine a high strength and stiffness with a relatively low density. These materials can, however, exhibit complex types of damage, like transverse cracks and delaminations. These damage scenarios can severely influence the structural performance of a component. Periodic inspecti

  15. Composition and structure of whey protein/gum arabic coacervates. (United States)

    Weinbreck, F; Tromp, R H; de Kruif, C G


    Complex coacervation in whey protein/gum arabic (WP/GA) mixtures was studied as a function of three main key parameters: pH, initial protein to polysaccharide mixing ratio (Pr:Ps)(ini), and ionic strength. Previous studies had already revealed under which conditions a coacervate phase was obtained. This study is aimed at understanding how these parameters influence the phase separation kinetics, the coacervate composition, and the internal coacervate structure. At a defined (Pr:Ps)(ini), an optimum pH of complex coacervation was found (pH(opt)), at which the strength of electrostatic interaction was maximum. For (Pr:Ps)(ini) = 2:1, the phase separation occurred the fastest and the final coacervate volume was the largest at pH(opt) = 4.0. The composition of the coacervate phase was determined after 48 h of phase separation and revealed that, at pH(opt), the coacervate phase was the most concentrated. Varying the (Pr:Ps)(ini) shifted the pH(opt) to higher values when (Pr:Ps)(ini) was increased and to lower values when (Pr:Ps)(ini) was decreased. This phenomenon was due to the level of charge compensation of the WP/GA complexes. Finally, the structure of the coacervate phase was studied with small-angle X-ray scattering (SAXS). SAXS data confirmed that at pH(opt) the coacervate phase was dense and structured. Model calculations revealed that the structure factor of WP induced a peak at Q = 0.7 nm(-1), illustrating that the coacervate phase was more structured, inducing the stronger correlation length of WP molecules. When the pH was changed to more acidic values, the correlation peak faded away, due to a more open structure of the coacervate. A shoulder in the scattering pattern of the coacervates was visible at small Q. This peak was attributed to the presence of residual charges on the GA. The peak intensity was reduced when the strength of interaction was increased, highlighting a greater charge compensation of the polyelectrolyte. Finally, increasing the ionic

  16. Advanced Technologies for Structural and Functional Optical Coherence Tomography (United States)


    bidirectional laser Doppler velocimetry (BLDV) combined with fundus photography is one of the most well suited methods for quantitative TRBF measurement...interventions or predict treatment outcomes. In another set of studies, we continued advancing the state of the art of the endoscopic OCT technology by...visualization by means of single-exposure speckle photography ," Optics Communications, vol. 37, pp. 326-330, 1981. [127] R. Bonner and R. Nossal, "Model for

  17. Guided wave diagnosis in composite grid structure with embedded FBG sensors (United States)

    Amano, Masataro; Arai, Takeo; Takeda, Nobuo


    The authors tried to construct a structural health monitoring (SHM) system to identify damage in composite grid structure called Advanced Grid Structure (AGS) by using two types of guided waves, compressional and flexural waves, propagating along ribs of AGS. Fiber Bragg grating (FBG) sensors network embedded in AGS is utilized as their receivers. AGS is defined as trussed structures whose ribs are made of Carbon fiber reinforced plastic (CFRP). AGS has often been applied to aerospace structures because it is structurally effective and redundant. The authors had reported one possible method of SHM of AGS by monitoring of static strain distribution with embedded FBG sensors network in AGS. In this paper, we propose another possible method of SHM of AGS. We utilized two types of guided waves, compressional and flexural waves, for damage diagnosis. First, we verified our proposed system experimentally. The results confirmed that FBG sensors could measure both elastic waves and two types of guided waves were generated with the proposed system. Then, some basic characteristics of compressional and flexural wave propagations were clarified experimentally to find that compressional wave has directionality and flexural wave has isotropy. Based on the characteristics, the authors proposed two types of damage diagnosis methods with compressional and flexural waves, respectively. Moreover, those proposed methods were applied to two specific damage types, rib crack and debonding between ribs and skin. The specific damage diagnosis methods were verified experimentally to find that damages could be detected by those methods.

  18. Relating performance of thin-film composite forward osmosis membranes to support layer formation and structure

    KAUST Repository

    Tiraferri, Alberto


    Osmotically driven membrane processes have the potential to treat impaired water sources, desalinate sea/brackish waters, and sustainably produce energy. The development of a membrane tailored for these processes is essential to advance the technology to the point that it is commercially viable. Here, a systematic investigation of the influence of thin-film composite membrane support layer structure on forward osmosis performance is conducted. The membranes consist of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation. By systematically varying the conditions used during the casting of the polysulfone layer, an array of support layers with differing structures was produced. The role that solvent quality, dope polymer concentration, fabric layer wetting, and casting blade gate height play in the support layer structure formation was investigated. Using a 1M NaCl draw solution and a deionized water feed, water fluxes ranging from 4 to 25Lm-2h-1 with consistently high salt rejection (>95.5%) were produced. The relationship between membrane structure and performance was analyzed. This study confirms the hypothesis that the optimal forward osmosis membrane consists of a mixed-structure support layer, where a thin sponge-like layer sits on top of highly porous macrovoids. Both the active layer transport properties and the support layer structural characteristics need to be optimized in order to fabricate a high performance forward osmosis membrane. © 2010 Elsevier B.V.

  19. Online Damage Detection on Metal and Composite Space Structures by Active and Passive Acoustic Methods (United States)

    Scheerer, M.; Cardone, T.; Rapisarda, A.; Ottaviano, S.; Ftancesconi, D.


    In the frame of ESA funded programme Future Launcher Preparatory Programme Period 1 “Preparatory Activities on M&S”, Aerospace & Advanced Composites and Thales Alenia Space-Italia, have conceived and tested a structural health monitoring approach based on integrated Acoustic Emission - Active Ultrasound Damage Identification. The monitoring methods implemented in the study are both passive and active methods and the purpose is to cover large areas with a sufficient damage size detection capability. Two representative space sub-structures have been built and tested: a composite overwrapped pressure vessel (COPV) and a curved, stiffened Al-Li panel. In each structure, typical critical damages have been introduced: delaminations caused by impacts in the COPV and a crack in the stiffener of the Al-Li panel which was grown during a fatigue test campaign. The location and severity of both types of damages have been successfully assessed online using two commercially available systems: one 6 channel AE system from Vallen and one 64 channel AU system from Acellent.

  20. Application of Percolation Theory to Complex Interconnected Networks in Advanced Functional Composites (United States)

    Hing, P.


    Percolation theory deals with the behaviour of connected clusters in a system. Originally developed for studying the flow of liquid in a porous body, the percolation theory has been extended to quantum computation and communication, entanglement percolation in quantum networks, cosmology, chaotic situations, properties of disordered solids, pandemics, petroleum industry, finance, control of traffic and so on. In this paper, the application of various models of the percolation theory to predict and explain the properties of a specially developed family of dense sintered and highly refractory Al2O3-W composites for potential application in high intensity discharge light sources such as high pressure sodium lamps and ceramic metal halide lamps are presented and discussed. The low cost, core-shell concept can be extended to develop functional composite materials with unusual dielectric, electrical, magnetic, superconducting, and piezoelectric properties starting from a classical insulator. The core shell concept can also be applied to develop catalysts with high specific surface areas with minimal amount of expensive platinium, palladium or rare earth nano structured materials for light harvesting, replicating natural photosynthesis, in synthetic zeolite composites for the cracking and separation of crude oil. There is also possibility of developing micron and nanosize Faraday cages for quantum devices, nano electronics and spintronics. The possibilities are limitless.

  1. New Materials for Structural Composites and Protective Coatings (United States)


    The objective of this Phase I project was to create novel conductive materials that are lightweight and strong enough for multiple ground support equipment and Exploration applications. The long-term goal is to combine these materials within specially designed devices to create composites or coatings with diagnostic capabilities, increased strength, and tunable properties such as transparency, electroluminescence, and fire resistance. One such technology application is a smart windows system. In such a system, the transmission of light through a window is controlled by electrical power. In the future, these materials may also be able to absorb sunlight and convert it into electrical energy to produce light, thereby creating a self-sufficient lighting system. This experiment, conducted in collaboration with the Georgia Institute of Technology, demonstrated enhancements in fabricating fiber materials from carbon nanotubes (CNT). These nanotubes were grown as forests in an ultra-high-purity chemical vapor deposition (CVD) furnace and then drawn, using novel processing techniques, into fibers and yarns that would be turned into filaments. This work was submitted to the Journal of Advanced Functional Materials. The CNT fibers were initially tested as filament materials at atmospheric pressure; however, even under high current loads, the filaments produced only random sparking. The CNT fibers were also converted into transparent, hydrophobic, and conductive sheets. Filament testing at low vacuum pressures is in progress, and the technology will be enhanced in 2008. As initial proof of the smart-windows application concept, the use of CNT sheets as composites/ protective coatings was demonstrated in collaboration with Nanocomp Technologies of Concord, New Hampshire.

  2. Preface: Special Topic Section on Advanced Electronic Structure Methods for Solids and Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Michaelides, Angelos, E-mail: [London Centre for Nanotechnology and Department of Chemistry, University College London, London (United Kingdom); Martinez, Todd J. [Department of Chemistry and the PULSE Institute, Stanford University, Stanford, California 94305, USA and SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Alavi, Ali [Max Planck Institute for Solid State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany and Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Kresse, Georg [Faculty of Physics and Center for Computational Materials Science, Department of Physics, University of Vienna, Sensengasse 8/12, A-1090 Vienna (Austria); Manby, Frederick R. [Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom)


    This Special Topic section on Advanced Electronic Structure Methods for Solids and Surfaces contains a collection of research papers that showcase recent advances in the high accuracy prediction of materials and surface properties. It provides a timely snapshot of a growing field that is of broad importance to chemistry, physics, and materials science.

  3. Automated laser-based barely visible impact damage detection in honeycomb sandwich composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Girolamo, D., E-mail:; Yuan, F. G. [National Institute of Aerospace, Integrated Structural Health Management Laboratory, Hampton, VA 23666 and North Carolina State University, Department of Mechanical and Aerospace Engineering, Raleigh, NC 27695 (United States); Girolamo, L. [North Carolina State University, Department of Mechanical and Aerospace Engineering, Raleigh, NC 27695 (United States)


    Nondestructive evaluation (NDE) for detection and quantification of damage in composite materials is fundamental in the assessment of the overall structural integrity of modern aerospace systems. Conventional NDE systems have been extensively used to detect the location and size of damages by propagating ultrasonic waves normal to the surface. However they usually require physical contact with the structure and are time consuming and labor intensive. An automated, contactless laser ultrasonic imaging system for barely visible impact damage (BVID) detection in advanced composite structures has been developed to overcome these limitations. Lamb waves are generated by a Q-switched Nd:YAG laser, raster scanned by a set of galvano-mirrors over the damaged area. The out-of-plane vibrations are measured through a laser Doppler Vibrometer (LDV) that is stationary at a point on the corner of the grid. The ultrasonic wave field of the scanned area is reconstructed in polar coordinates and analyzed for high resolution characterization of impact damage in the composite honeycomb panel. Two methodologies are used for ultrasonic wave-field analysis: scattered wave field analysis (SWA) and standing wave energy analysis (SWEA) in the frequency domain. The SWA is employed for processing the wave field and estimate spatially dependent wavenumber values, related to discontinuities in the structural domain. The SWEA algorithm extracts standing waves trapped within damaged areas and, by studying the spectrum of the standing wave field, returns high fidelity damage imaging. While the SWA can be used to locate the impact damage in the honeycomb panel, the SWEA produces damage images in good agreement with X-ray computed tomographic (X-ray CT) scans. The results obtained prove that the laser-based nondestructive system is an effective alternative to overcome limitations of conventional NDI technologies.

  4. [Compositions and structure characterizations of coal tar refined soft pitch]. (United States)

    Gao, Li-Juan; Zhao, Xue-Fei; Lai, Shi-Quan; Cheng, Jun-Xia; Lu, Yi-Qiang


    High temperature coal tar was used as raw materials, and was distilled to 280 degrees C for getting coal tar soft pitch. Then refined soft pitch was obtained by solvent extracting and subsequent settlement method. Its soft point was 32 degrees C; the group compositions consisted of 53.67% heptane soluble, 39.47% heptane insoluble but toluene soluble, 6.86% toluene insoluble and 0.06% quinoline insoluble. The relative average molecular weight was about 292. Its average molecular formula was C22.22 H16.32 N0.12 S0.06 O0.33; the total content of heteroatom was less than 1. IR analytic results showed that its heteroatom O existed in the R-O-R and Ar-O-R structure; its heteroatom N existed in the R-NH-R and -N=, with the latter being primary. Its average structure was obtained by improved Brown-Lander model: five-membered condensed rings. UV analysis indicated that the majority was linear arrangement, and the minority was surface arrangement; namely, the chemical structure of the samples was mainly the cata-condensed structure, while the minority was peri-condensation.

  5. Composite structure of wood cells in petrified wood

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, Jakub [Department of Chemistry, Catholic University of Lublin, 20-718 Lublin (Poland); Florek, Marek [Department of Chemistry, Catholic University of Lublin, 20-718 Lublin (Poland); Kwiatek, Wojciech [Institute of Nuclear Physics, Department of Nuclear Spectroscopy, 31-342 Cracow (Poland); Lekki, Janusz [Institute of Nuclear Physics, Department of Nuclear Spectroscopy, 31-342 Cracow (Poland); Chevallier, Pierre [LPS, CEN Saclay et LURE, Universite Paris-Sud, Bat 209D, F-91405 Orsay (France); Zieba, Emil [Department of Chemistry, Catholic University of Lublin, 20-718 Lublin (Poland); Mestres, Narcis [Institut de Ciencia de Materials de Barcelona (ICMAB), Campus de la UAB, E-08193-Bellaterra (Spain); Dutkiewicz, E.M. [Institute of Nuclear Physics, Department of Nuclear Spectroscopy, 31-342 Cracow (Poland); Kuczumow, Andrzej [Department of Chemistry, Catholic University of Lublin, 20-718 Lublin (Poland)


    Special kinds of petrified wood of complex structure were investigated. All the samples were composed of at least two different inorganic substances. The original cell structure was preserved in each case. The remnants of the original biological material were detected in some locations, especially in the cell walls. The complex inorganic structure was superimposed on the remnant organic network. The first inorganic component was located in the lumena (l.) of the cells while another one in the walls (w.) of the cells. The investigated arrangements were as follows: calcite (l.)-goethite-hematite (w.)-wood from Dunarobba, Italy; pyrite (l.)-calcite (w.)-wood from Lukow, Poland; goethite (l.)-silica (w.)-wood from Kwaczala, Poland. The inorganic composition was analysed and spatially located by the use of three spectral methods: electron microprobe, X-ray synchrotron-based microprobe, {mu}-PIXE microprobe. The accurate mappings presenting 2D distribution of the chemical species were presented for each case. Trace elements were detected and correlated with the distribution of the main elements. In addition, the identification of phases was done by the use of {mu}-Raman and {mu}-XRD techniques for selected and representative points. The possible mechanisms of the described arrangements are considered. The potential synthesis of similar structures and their possible applications are suggested.

  6. PREFACE: International Conference on Structural Nano Composites (NANOSTRUC 2012) (United States)

    Njuguna, James


    Dear Colleagues It is a great pleasure to welcome you to NanoStruc2012 at Cranfield University. The purpose of the 2012 International Conference on Structural Nano Composites (NanoStruc2012) is to promote activities in various areas of materials and structures by providing a forum for exchange of ideas, presentation of technical achievements and discussion of future directions. NanoStruc brings together an international community of experts to discuss the state-of-the-art, new research results, perspectives of future developments, and innovative applications relevant to structural materials, engineering structures, nanocomposites, modelling and simulations, and their related application areas. The conference is split in 7 panel sessions, Metallic Nanocomposites and Coatings, Silica based Nanocomposites, safty of Nanomaterials, Carboin based Nanocomposites, Multscale Modelling, Bio materials and Application of Nanomaterials. All accepted Papers will be published in the IOP Conference Series: Materials Science and Engineering (MSE), and included in the NanoStruc online digital library. The abstracts will be indexed in Scopus, Compedex, Inspec, INIS (International Nuclear Information System), Chemical Abstracts, NASA Astrophysics Data System and Polymer Library. Before ending this message, I would like to acknowledge the hard work, professional skills and efficiency of the team which ensured the general organisation. As a conclusion, I would like to Welcome you to the Nanostruc2012 and wish you a stimulating Conference and a wonderful time. On behalf of the scientific committee, Signature James Njuguna Conference Chair The PDF of this preface also contains committee listings and associates logos.

  7. Compositions comprising enhanced graphene oxide structures and related methods

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Priyank Vijaya; Bardhan, Neelkanth M.; Belcher, Angela; Grossman, Jeffrey


    Embodiments described herein generally relate to compositions comprising a graphene oxide species. In some embodiments, the compositions advantageously have relatively high oxygen content, even after annealing.

  8. High Thermal Conductivity Polymer Matrix Composites (PMC) for Advanced Space Radiators (United States)

    Shin, E. Eugene; Bowman, Cheryl; Beach, Duane


    High temperature polymer matrix composites (PMC) reinforced with high thermal conductivity (approx. 1000 W/mK) pitch-based carbon fibers are evaluated for a facesheet/fin structure of large space radiator systems. Significant weight reductions along with improved thermal performance, structural integrity and space durability toward its metallic counterparts were envisioned. Candidate commercial resin systems including Cyanate Esters, BMIs, and polyimide were selected based on thermal capabilities and processability. PMC laminates were designed to match the thermal expansion coefficient of various metal heat pipes or tubes. Large, but thin composite panels were successfully fabricated after optimizing cure conditions. Space durability of PMC with potential degradation mechanisms was assessed by simulated thermal aging tests in high vacuum, 1-3 x 10(exp -6) torr, at three temperatures, 227 C, 277 C, and 316 C for up to one year. Nanocomposites with vapor-grown carbon nano-fibers and exfoliated graphite flakes were attempted to improve thermal conductivity (TC) and microcracking resistance. Good quality nanocomposites were fabricated and evaluated for TC and durability including radiation resistance. TC was measured in both in-plan and thru-the-thickness directions, and the effects of microcracks on TC are also being evaluated. This paper will discuss the systematic experimental approaches, various performance-durability evaluations, and current subcomponent design and fabrication/manufacturing efforts.

  9. FAA/NASA International Symposium on Advanced Structural Integrity Methods for Airframe Durability and Damage Tolerance (United States)

    Harris, Charles E. (Editor)


    International technical experts in durability and damage tolerance of metallic airframe structures were assembled to present and discuss recent research findings and the development of advanced design and analysis methods, structural concepts, and advanced materials. The symposium focused on the dissemination of new knowledge and the peer-review of progress on the development of advanced methodologies. Papers were presented on: structural concepts for enhanced durability, damage tolerance, and maintainability; new metallic alloys and processing technology; fatigue crack initiation and small crack effects; fatigue crack growth models; fracture mechanics failure, criteria for ductile materials; structural mechanics methodology for residual strength and life prediction; development of flight load spectra for design and testing; and advanced approaches to resist corrosion and environmentally assisted fatigue.

  10. Unit cell geometry of multiaxial preforms for structural composites (United States)

    Ko, Frank; Lei, Charles; Rahman, Anisur; Du, G. W.; Cai, Yun-Jia


    The objective of this study is to investigate the yarn geometry of multiaxial preforms. The importance of multiaxial preforms for structural composites is well recognized by the industry but, to exploit their full potential, engineering design rules must be established. This study is a step in that direction. In this work the preform geometry for knitted and braided preforms was studied by making a range of well designed samples and studying them by photo microscopy. The structural geometry of the preforms is related to the processing parameters. Based on solid modeling and B-spline methodology a software package is developed. This computer code enables real time structural representations of complex fiber architecture based on the rule of preform manufacturing. The code has the capability of zooming and section plotting. These capabilities provide a powerful means to study the effect of processing variables on the preform geometry. the code also can be extended to an auto mesh generator for downstream structural analysis using finite element method. This report is organized into six sections. In the first section the scope and background of this work is elaborated. In section two the unit cell geometries of braided and multi-axial warp knitted preforms is discussed. The theoretical frame work of yarn path modeling and solid modeling is presented in section three. The thin section microscopy carried out to observe the structural geometry of the preforms is the subject in section four. The structural geometry is related to the processing parameters in section five. Section six documents the implementation of the modeling techniques into the computer code MP-CAD. A user manual for the software is also presented here. The source codes and published papers are listed in the Appendices.

  11. Strength of Composite Joints in Structural Components and Articles

    Directory of Open Access Journals (Sweden)

    A. A. Bakulin


    Full Text Available Currently, the composite materials (CM are widely used in the aerospace technology and mechanical engineering where the key parameters characterizing structural components and articles are related to their weight characteristics as well as their performance under high temperatures.For the experimental investigation of composite-based threaded items, the rod-based 3Dreinforced carbon-carbon composite material (CCCM was chosen.The subject of the research was the metric thread. The test samples were cut of the aforesaid material along one of the reinforcement direction. The following thread sizes were analyzed: М24×1.5; М24×2; М24×3.Dependence of the thread strength on the number of thread turns was determined within the range of 1 to 10 thread turns for М24×2 thread size. The remaining test samples were used to obtain the relationship between the thread load bearing capacity and the thread pitch.The obtained dependence of the thread load bearing capacity on the number of thread turns showed the following:a An increment in the thread load bearing capacity decreases with increasing number of thread turns. However, this effect is less pronounced than that observed for the metal ‘screw/nut’ pair.b With the CCCM material under study, it proved to be impossible to test configurations having only 1 or 2 thread turns.c The wide confidence range (CR of the failure load can be explained by the fact that the material under study features an apparent structural heterogeneity, with a different probability of hitting a unit cell of the matrix and filler of the material. Nevertheless, the confidence range is stable, thus indicating indirectly the possibility of using this test method for further study of composite-based threaded items.There is an explicit correlation between the thread load bearing capacity and the thread pitch. Increase in the thread strength with increasing thread pitch depends on the relationship between the pitch size and the

  12. Damage prognosis of adhesively-bonded joints in laminated composite structural components of unmanned aerial vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, Charles R [Los Alamos National Laboratory; Gobbato, Maurizio [UCSD; Conte, Joel [UCSD; Kosmatke, John [UCSD; Oliver, Joseph A [UCSD


    The extensive use of lightweight advanced composite materials in unmanned aerial vehicles (UAVs) drastically increases the sensitivity to both fatigue- and impact-induced damage of their critical structural components (e.g., wings and tail stabilizers) during service life. The spar-to-skin adhesive joints are considered one of the most fatigue sensitive subcomponents of a lightweight UAV composite wing with damage progressively evolving from the wing root. This paper presents a comprehensive probabilistic methodology for predicting the remaining service life of adhesively-bonded joints in laminated composite structural components of UAVs. Non-destructive evaluation techniques and Bayesian inference are used to (i) assess the current state of damage of the system and, (ii) update the probability distribution of the damage extent at various locations. A probabilistic model for future loads and a mechanics-based damage model are then used to stochastically propagate damage through the joint. Combined local (e.g., exceedance of a critical damage size) and global (e.g.. flutter instability) failure criteria are finally used to compute the probability of component failure at future times. The applicability and the partial validation of the proposed methodology are then briefly discussed by analyzing the debonding propagation, along a pre-defined adhesive interface, in a simply supported laminated composite beam with solid rectangular cross section, subjected to a concentrated load applied at mid-span. A specially developed Eliler-Bernoulli beam finite element with interlaminar slip along the damageable interface is used in combination with a cohesive zone model to study the fatigue-induced degradation in the adhesive material. The preliminary numerical results presented are promising for the future validation of the methodology.

  13. Cladding and Structural Materials for Advanced Nuclear Energy Systems

    Energy Technology Data Exchange (ETDEWEB)

    Was, G S; Allen, T R; Ila, D; C,; Levi,; Morgan, D; Motta, A; Wang, L; Wirth, B


    The goal of this consortium is to address key materials issues in the most promising advanced reactor concepts that have yet to be resolved or that are beyond the existing experience base of dose or burnup. The research program consists of three major thrusts: 1) high-dose radiation stability of advanced fast reactor fuel cladding alloys, 2) irradiation creep at high temperature, and 3) innovative cladding concepts embodying functionally-graded barrier materials. This NERI-Consortium final report represents the collective efforts of a large number of individuals over a period of three and a half years and included 9 PIs, 4 scientists, 3 post-docs and 12 students from the seven participating institutions and 8 partners from 5 national laboratories and 3 industrial institutions (see table). University participants met semi-annually and participants and partners met annually for meetings lasting 2-3 days and designed to disseminate and discuss results, update partners, address outstanding issues and maintain focus and direction toward achieving the objectives of the program. The participants felt that this was a highly successful program to address broader issues that can only be done by the assembly of a range of talent and capabilities at a more substantial funding level than the traditional NERI or NEUP grant. As evidence of the success, this group, collectively, has published 20 articles in archival journals and made 57 presentations at international conferences on the results of this consortium.

  14. Structural Dynamics Testing of Advanced Stirling Convertor Components (United States)

    Oriti, Salvatore M.; Williams, Zachary Douglas


    NASA Glenn Research Center has been supporting the development of Stirling energy conversion for use in space. Lockheed Martin has been contracted by the Department of Energy to design and fabricate flight-unit Advanced Stirling Radioisotope Generators, which utilize Sunpower, Inc., free-piston Advanced Stirling Convertors. The engineering unit generator has demonstrated conversion efficiency in excess of 20 percent, offering a significant improvement over existing radioisotope-fueled power systems. NASA Glenn has been supporting the development of this generator by developing the convertors through a technology development contract with Sunpower, and conducting research and experiments in a multitude of areas, such as high-temperature material properties, organics testing, and convertor-level extended operation. Since the generator must undergo launch, several launch simulation tests have also been performed at the convertor level. The standard test sequence for launch vibration exposure has consisted of workmanship and flight acceptance levels. Together, these exposures simulate what a flight convertor will experience. Recently, two supplementary tests were added to the launch vibration simulation activity. First was a vibration durability test of the convertor, intended to quantify the effect of vibration levels up to qualification level in both the lateral and axial directions. Second was qualification-level vibration of several heater heads with small oxide inclusions in the material. The goal of this test was to ascertain the effect of the inclusions on launch survivability to determine if the heater heads were suitable for flight.

  15. Material Distribution Optimization for the Shell Aircraft Composite Structure (United States)

    Shevtsov, S.; Zhilyaev, I.; Oganesyan, P.; Axenov, V.


    One of the main goal in aircraft structures designing isweight decreasing and stiffness increasing. Composite structures recently became popular in aircraft because of their mechanical properties and wide range of optimization possibilities.Weight distribution and lay-up are keys to creating lightweight stiff strictures. In this paperwe discuss optimization of specific structure that undergoes the non-uniform air pressure at the different flight conditions and reduce a level of noise caused by the airflowinduced vibrations at the constrained weight of the part. Initial model was created with CAD tool Siemens NX, finite element analysis and post processing were performed with COMSOL Multiphysicsr and MATLABr. Numerical solutions of the Reynolds averaged Navier-Stokes (RANS) equations supplemented by k-w turbulence model provide the spatial distributions of air pressure applied to the shell surface. At the formulation of optimization problem the global strain energy calculated within the optimized shell was assumed as the objective. Wall thickness has been changed using parametric approach by an initiation of auxiliary sphere with varied radius and coordinates of the center, which were the design variables. To avoid a local stress concentration, wall thickness increment was defined as smooth function on the shell surface dependent of auxiliary sphere position and size. Our study consists of multiple steps: CAD/CAE transformation of the model, determining wind pressure for different flow angles, optimizing wall thickness distribution for specific flow angles, designing a lay-up for optimal material distribution. The studied structure was improved in terms of maximum and average strain energy at the constrained expense ofweight growth. Developed methods and tools can be applied to wide range of shell-like structures made of multilayered quasi-isotropic laminates.

  16. Structural advances for the major facilitator superfamily (MFS) transporters. (United States)

    Yan, Nieng


    The major facilitator superfamily (MFS) is one of the largest groups of secondary active transporters conserved from bacteria to humans. MFS proteins selectively transport a wide spectrum of substrates across biomembranes and play a pivotal role in multiple physiological processes. Despite intense investigation, only seven MFS proteins from six subfamilies have been structurally elucidated. These structures were captured in distinct states during a transport cycle involving alternating access to binding sites from either side of the membrane. This review discusses recent progress in MFS structure analysis and focuses on the molecular basis for substrate binding, co-transport coupling, and alternating access.

  17. Characterization of the structure and composition of gecko adhesive setae. (United States)

    Rizzo, N W; Gardner, K H; Walls, D J; Keiper-Hrynko, N M; Ganzke, T S; Hallahan, D L


    The ability of certain reptiles to adhere to vertical (and hang from horizontal) surfaces has been attributed to the presence of specialized adhesive setae on their feet. Structural and compositional studies of such adhesive setae will contribute significantly towards the design of biomimetic fibrillar adhesive materials. The results of electron microscopy analyses of the structure of such setae are presented, indicating their formation from aggregates of proteinaceous fibrils held together by a matrix and potentially surrounded by a limiting proteinaceous sheath. Microbeam X-ray diffraction analysis has shown conclusively that the only ordered protein constituent in these structures exhibits a diffraction pattern characteristic of beta-keratin. Raman microscopy of individual setae, however, clearly shows the presence of additional protein constituents, some of which may be identified as alpha-keratins. Electrophoretic analysis of solubilized setal proteins supports these conclusions, indicating the presence of a group of low-molecular-weight beta-keratins (14-20 kDa), together with alpha-keratins, and this interpretation is supported by immunological analyses.

  18. Smart aircraft composite structures with embedded small-diameter optical fiber sensors (United States)

    Takeda, Nobuo; Minakuchi, Shu


    This talk describes the embedded optical fiber sensor systems for smart aircraft composite structures. First, a summary of the current Japanese national project on structural integrity diagnosis of aircraft composite structures is described with special emphasis on the use of embedded small-diameter optical fiber sensors including FBG sensors. Then, some examples of life-cycle monitoring of aircraft composite structures are presented using embedded small-diameter optical fiber sensors for low-cost and reliable manufacturing merits.

  19. Resin infusion of large composite structures modeling and manufacturing process

    Energy Technology Data Exchange (ETDEWEB)

    Loos, A.C. [Michigan State Univ., Dept. of Mechanical Engineering, East Lansing, MI (United States)


    The resin infusion processes resin transfer molding (RTM), resin film infusion (RFI) and vacuum assisted resin transfer molding (VARTM) are cost effective techniques for the fabrication of complex shaped composite structures. The dry fibrous preform is placed in the mold, consolidated, resin impregnated and cured in a single step process. The fibrous performs are often constructed near net shape using highly automated textile processes such as knitting, weaving and braiding. In this paper, the infusion processes RTM, RFI and VARTM are discussed along with the advantages of each technique compared with traditional composite fabrication methods such as prepreg tape lay up and autoclave cure. The large number of processing variables and the complex material behavior during infiltration and cure make experimental optimization of the infusion processes costly and inefficient. Numerical models have been developed which can be used to simulate the resin infusion processes. The model formulation and solution procedures for the VARTM process are presented. A VARTM process simulation of a carbon fiber preform was presented to demonstrate the type of information that can be generated by the model and to compare the model predictions with experimental measurements. Overall, the predicted flow front positions, resin pressures and preform thicknesses agree well with the measured values. The results of the simulation show the potential cost and performance benefits that can be realized by using a simulation model as part of the development process. (au)

  20. On the Deflexion of Anisotropic Structural Composite Aerodynamic Components

    Directory of Open Access Journals (Sweden)

    J. Whitty


    Full Text Available This paper presents closed form solutions to the classical beam elasticity differential equation in order to effectively model the displacement of standard aerodynamic geometries used throughout a number of industries. The models assume that the components are constructed from in-plane generally anisotropic (though shown to be quasi-isotropic composite materials. Exact solutions for the displacement and strains for elliptical and FX66-S-196 and NACA 63-621 aerofoil approximations thin wall composite material shell structures, with and without a stiffening rib (shear-web, are presented for the first time. Each of the models developed is rigorously validated via numerical (Runge-Kutta solutions of an identical differential equation used to derive the analytical models presented. The resulting calculated displacement and material strain fields are shown to be in excellent agreement with simulations using the ANSYS and CATIA commercial finite element (FE codes as well as experimental data evident in the literature. One major implication of the theoretical treatment is that these solutions can now be used in design codes to limit the required displacement and strains in similar components used in the aerospace and most notably renewable energy sectors.

  1. Health monitoring of composite structures throughout the life cycle (United States)

    Chilles, James; Croxford, Anthony; Bond, Ian


    This study demonstrates the capability of inductively coupled piezoelectric sensors to monitor the state of health throughout the lifetime of composite structures. A single sensor which generated guided elastic waves was embedded into the stacking sequence of a large glass fiber reinforced plastic plate. The progress of cure was monitored by measuring variations in the amplitude and velocity of the waveforms reflected from the plate's edges. Baseline subtraction techniques were then implemented to detect barely visible impact damage (BVID) created by a 10 Joule impact, at a distance of 350 mm from the sensor embedded in the cured plate. To investigate the influence of mechanical loading on sensor performance, a single sensor was embedded within a glass fiber panel and subjected to tensile load. The panel was loaded up to a maximum strain of 1%, in increments of 0.1% strain. Guided wave measurements were recorded by the embedded sensor before testing, when the panel was under load, and after testing. The ultrasonic measurements showed a strong dependence on the applied load. Upon removal of the mechanical load the guided wave measurements returned to their original values recorded before testing. The results in this work show that embedded piezoelectric sensors can be used to monitor the state of health throughout the life-cycle of composite parts, even when subjected to relatively large strains. However the influence of load on guided wave measurements has implications for online monitoring using embedded piezoelectric transducers.

  2. Mechanistic Effects of Porosity on Structural Composite Materials (United States)

    Siver, Andrew

    As fiber reinforced composites continue to gain popularity as primary structures in aerospace, automotive, and powersports industries, quality control becomes an extremely important aspect of materials and mechanical engineering. The ability to recognize and control manufacturing induced defects can greatly reduce the likelihood of unexpected catastrophic failure. Porosity is the result of trapped volatiles or air bubbles during the layup process and can significantly compromise the strength of fiber reinforced composites. A comprehensive study was performed on an AS4C-UF3352 TCR carbon fiber-epoxy prepreg system to determine the effect of porosity on flexural, shear, low-velocity impact, and damage residual strength properties. Autoclave cure pressure was controlled to induce varying levels of porosity to construct six laminates with porosity concentrations between 0-40%. Porosity concentrations were measured using several destructive and nondestructive techniques including resin burnoff, sectioning and optical analysis, and X-ray computed tomography (CT) scanning. Ultrasonic transmission, thermography, and CT scanning provided nondestructive imaging to evaluate impact damage. A bilinear relationship accurately characterizes the change in mechanical properties with increasing porosity. Strength properties are relatively unaffected when porosity concentrations are below approximately 2.25% and decrease linearly by up to 40% in high porosity specimens.

  3. Possible Internal Structures and Compositions of Proxima Centauri b

    CERN Document Server

    Brugger, B; Deleuil, M; Lunine, J I


    We explore the possible Proxima Centauri b's interiors assuming the planet belongs to the class of dense solid planets (rocky with possible addition of water) and derive the corresponding radii. To do so, we use an internal structure model that computes the radius of the planet along with the locations of the different layers of materials, assuming that its mass and bulk composition are known. Lacking detailed elementary abundances of the host star to constrain the planet's composition, we base our model on solar system values. We restrained the simulations to the case of solid planets without massive atmospheres. With these assumptions, the possible radius of Proxima Centauri b spans the 0.94--1.40 $R_\\oplus$ range. The minimum value is obtained considering a 1.10 $M_\\oplus$ Mercury-like planet with a 65% core mass fraction, whereas the highest radius is reached for 1.46 $M_\\oplus$ with 50% water in mass, constituting an ocean planet. Although this range of radii still allows very different planet compositio...

  4. Modeling Forced Flow Chemical Vapor Infiltration Fabrication of SiC-SiC Composites for Advanced Nuclear Reactors

    Directory of Open Access Journals (Sweden)

    Christian P. Deck


    Full Text Available Silicon carbide fiber/silicon carbide matrix (SiC-SiC composites exhibit remarkable material properties, including high temperature strength and stability under irradiation. These qualities have made SiC-SiC composites extremely desirable for use in advanced nuclear reactor concepts, where higher operating temperatures and longer lives require performance improvements over conventional metal alloys. However, fabrication efficiency advances need to be achieved. SiC composites are typically produced using chemical vapor infiltration (CVI, where gas phase precursors flow into the fiber preform and react to form a solid SiC matrix. Forced flow CVI utilizes a pressure gradient to more effectively transport reactants into the composite, reducing fabrication time. The fabrication parameters must be well understood to ensure that the resulting composite has a high density and good performance. To help optimize this process, a computer model was developed. This model simulates the transport of the SiC precursors, the deposition of SiC matrix on the fiber surfaces, and the effects of byproducts on the process. Critical process parameters, such as the temperature and reactant concentration, were simulated to identify infiltration conditions which maximize composite density while minimizing the fabrication time.

  5. Application of Advanced Radiation Shielding Materials to Inflatable Structures Project (United States)

    National Aeronautics and Space Administration — This innovation is a weight-optimized, inflatable structure that incorporates radiation shielding materials into its construction, for use as a habitation module or...

  6. The entrance system laboratory prototype for an advanced mass and ionic charge composition experiment. (United States)

    Allegrini, F; Desai, M I; Livi, R; Livi, S; McComas, D J; Randol, B


    Electrostatic analyzers (ESA) have been used extensively for the characterization of plasmas in a variety of space environments. They vary in shape, geometry, and size and are adapted to the specific particle population to be measured and the configuration of the spacecraft. Their main function is to select the energy per charge of the particles within a passband. An energy-per-charge range larger than that of the passband can be sampled by varying the voltage difference between the ESA electrodes. The voltage sweep takes time and reduces the duty cycle for a particular energy-per-charge passband. Our design approach for an advanced mass and ionic charge composition experiment (AMICCE) has a novel electrostatic analyzer that essentially serves as a spectrograph and selects ions simultaneously over a broad range of energy-per-charge (E/q). Only three voltage settings are required to cover the entire range from approximately 10 to 270 keV/q, thus dramatically increasing the product of the geometric factor times the duty cycle when compared with other instruments. In this paper, we describe the AMICCE concept with particular emphasis on the prototype of the entrance system (ESA and collimator), which we designed, developed, and tested. We also present comparisons of the laboratory results with electrostatic simulations.

  7. Recent Advances in the Composition and Heterogeneity of the Arabidopsis Mitochondrial Proteome

    Directory of Open Access Journals (Sweden)

    Chun Pong eLee


    Full Text Available Mitochondria are important organelles for providing the ATP and carbon skeletons required to sustain cell growth. While these organelles also participate in other key metabolic functions across species, they have a specialized role in plants of optimizing photosynthesis through participating in photorespiration. It is therefore critical to map the protein composition of mitochondria in plants to gain a better understanding of their regulation and define the uniqueness of their metabolic networks. To date, less than 30% of the predicted number of mitochondrial proteins has been verified experimentally by proteomics and/or GFP localization studies. In this mini-review, we will provide an overview of the advances in mitochondrial proteomics in the model plant Arabidopsis thaliana over the past five years. The ultimate goal of mapping the mitochondrial proteome in Arabidopsis is to discover novel mitochondrial components that are critical during development in plants as well as genes involved in developmental abnormalities, such as those implicated in mitochondrial-linked cytoplasmic male sterility.

  8. Breakthrough and future: nanoscale controls of compositions, morphologies, and mesochannel orientations toward advanced mesoporous materials. (United States)

    Yamauchi, Yusuke; Suzuki, Norihiro; Radhakrishnan, Logudurai; Wang, Liang


    Currently, ordered mesoporous materials prepared through the self-assembly of surfactants have attracted growing interests owing to their special properties, including uniform mesopores and a high specific surface area. Here we focus on fine controls of compositions, morphologies, mesochannel orientations which are important factors for design of mesoporous materials with new functionalities. This Review describes our recent progress toward advanced mesoporous materials. Mesoporous materials now include a variety of inorganic-based materials, for example, transition-metal oxides, carbons, inorganic-organic hybrid materials, polymers, and even metals. Mesoporous metals with metallic frameworks can be produced by using surfactant-based synthesis with electrochemical methods. Owing to their metallic frameworks, mesoporous metals with high electroconductivity and high surface areas hold promise for a wide range of potential applications, such as electronic devices, magnetic recording media, and metal catalysts. Fabrication of mesoporous materials with controllable morphologies is also one of the main subjects in this rapidly developing research field. Mesoporous materials in the form of films, spheres, fibers, and tubes have been obtained by various synthetic processes such as evaporation-mediated direct templating (EDIT), spray-dried techniques, and collaboration with hard-templates such as porous anodic alumina and polymer membranes. Furthermore, we have developed several approaches for orientation controls of 1D mesochannels. The macroscopic-scale controls of mesochannels are important for innovative applications such as molecular-scale devices and electrodes with enhanced diffusions of guest species.

  9. Fuel Distribution Estimate via Spin Period to Precession Period Ratio for the Advanced Composition Explorer (United States)

    DeHart, Russell; Smith, Eric; Lakin, John


    The spin period to precession period ratio of a non-axisymmetric spin-stabilized spacecraft, the Advanced Composition Explorer (ACE), was used to estimate the remaining mass and distribution of fuel within its propulsion system. This analysis was undertaken once telemetry suggested that two of the four fuel tanks had no propellant remaining, contrary to pre-launch expectations of the propulsion system performance. Numerical integration of possible fuel distributions was used to calculate moments of inertia for the spinning spacecraft. A Fast Fourier Transform (FFT) of output from a dynamics simulation was employed to relate calculated moments of inertia to spin and precession periods. The resulting modeled ratios were compared to the actual spin period to precession period ratio derived from the effect of post-maneuver nutation angle on sun sensor measurements. A Monte Carlo search was performed to tune free parameters using the observed spin period to precession period ratio over the life of the mission. This novel analysis of spin and precession periods indicates that at the time of launch, propellant was distributed unevenly between the two pairs of fuel tanks, with one pair having approximately 20% more propellant than the other pair. Furthermore, it indicates the pair of the tanks with less fuel expelled all of its propellant by 2014 and that approximately 46 kg of propellant remains in the other two tanks, an amount that closely matches the operational fuel accounting estimate. Keywords: Fuel Distribution, Moments of Inertia, Precession, Spin, Nutation

  10. Macroparticle Movement Velocity in Dusty Structures of Various Compositions

    CERN Document Server

    Khakhaev, A D; Podryadchikov, S F


    The results of experimental investigations of the movement velocity of a macroparticle in the dusty structures of various physicalchemical compositions formed in a stratified column of a dc glow discharge, are presented. The macroparticle substances are alumina (r = 10 - 35 microns), polydisperse Zn (r = 1 - 20 microns) and Zn0 (r = 20 - 35 microns). Plasma-forming gases are inert gases (Ne, Ar). The inverse relation between the velocity and the gas pressure (in the range 40-400 Pa) is found and, for the same material of macroparticles in different gas plasmas, is confirmed by theory and does not contradict observations. But, to explain a difference of quantitative data for macroparticles made from different materials in Ar plasma, the additional research is required.

  11. Optimal Design of Composite Structures Under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Marmaras, Konstantinos

    mixed integer 0–1 programming problems. The manufacturing constraints have been treated by developing explicit models with favorable properties. In this thesis we have developed and implemented special purpose global optimization methods and heuristic techniques for solving this class of problems......This thesis considers discrete multi material and thickness optimization of laminated composite structures including local failure criteria and manufacturing constraints. Our models closely follow an immediate extension of the Discrete Material Optimization scheme, which allows simultaneous....... The continuous relaxation of the mixed integer programming problems is being solved by an implementation of a primal–dual interior point method for nonlinear programming that updates the barrier parameter adaptively. The method is chosen for its excellent convergence properties and the ability of the method...

  12. Advanced Computational Dynamics Simulation of Protective Structures Research (United States)


    conditions. The earliest in-depth investigation of the arching action theory of unreinforced masonry walls was carried out by McDowell et al...Arching Action Theory of Masonry Walls”, Journal of Structural Division, Proceedings of ASCE, Paper 915, 1-18. Moradi, L. (2003). “Constitutive...E.L., McKee, K.E., ASCE, A.M., Sevin, E. (1956). “Arching Action Theory of Masonry Walls”, Journal of Structural Division, Proceedings of ASCE

  13. Finite element model updating of natural fibre reinforced composite structure in structural dynamics

    Directory of Open Access Journals (Sweden)

    Sani M.S.M.


    Full Text Available Model updating is a process of making adjustment of certain parameters of finite element model in order to reduce discrepancy between analytical predictions of finite element (FE and experimental results. Finite element model updating is considered as an important field of study as practical application of finite element method often shows discrepancy to the test result. The aim of this research is to perform model updating procedure on a composite structure as well as trying improving the presumed geometrical and material properties of tested composite structure in finite element prediction. The composite structure concerned in this study is a plate of reinforced kenaf fiber with epoxy. Modal properties (natural frequency, mode shapes, and damping ratio of the kenaf fiber structure will be determined using both experimental modal analysis (EMA and finite element analysis (FEA. In EMA, modal testing will be carried out using impact hammer test while normal mode analysis using FEA will be carried out using MSC. Nastran/Patran software. Correlation of the data will be carried out before optimizing the data from FEA. Several parameters will be considered and selected for the model updating procedure.

  14. Metallic layered composite materials produced by explosion welding: Structure, properties, and structure of the transition zone (United States)

    Mal'tseva, L. A.; Tyushlyaeva, D. S.; Mal'tseva, T. V.; Pastukhov, M. V.; Lozhkin, N. N.; Inyakin, D. V.; Marshuk, L. A.


    The structure, morphology, and microhardness of the transition zone in multilayer metallic composite joints are studied, and the cohesion strength of the plates to be joined, the mechanical properties of the formed composite materials, and fracture surfaces are analyzed. The materials to be joined are plates (0.1-1 mm thick) made of D16 aluminum alloy, high-strength maraging ZI90-VI (03Kh12N9K4M2YuT) steel, BrB2 beryllium bronze, and OT4-1 titanium alloy. Composite materials made of different materials are shown to be produced by explosion welding. The dependence of the interface shape (smooth or wavelike) on the physicomechanical properties of the materials to be joined is found. The formation of a wavelike interface is shown to result in the formation of intense-mixing regions in transition zones. Possible mechanisms of layer adhesion are discussed.

  15. Electron beam melting of advanced materials and structures (United States)

    Mahale, Tushar Ramkrishna

    Layered manufacturing has for long been used for the fabrication of non-functional parts using polymer-based processes. Developments in laser beam and electron beam welding technologies and their adoption to layered manufacturing has made it possible to fabricate high-density functional parts in metal irrespective of the level of complexity. The Electron Beam Melting (EBM) process by Arcam AB is one such layered manufacturing process that utilizes a focused electron beam to process metal powder, layer by layer, in a vacuum environment. Research conducted as part of this body of work looks into the development of both bulk materials in the form of metal alloys and ceramic metal-matrix composites as well as the development of tunable mechanical & thermal metamaterials. Simulation models to approximate electron beam melting were suggested using commercial finite element analysis packages. A framework was developed based on the finite difference method to simulate layered manufacturing using Arcam AB's electron beam melting process. The outputs from the simulation data could be used to better understand the local melting, grain evolution, composition and internal stresses within freeform-fabricated metal parts.

  16. Additive technology of soluble mold tooling for embedded devices in composite structures: A study on manufactured tolerances (United States)

    Roy, Madhuparna

    Composite textiles have found widespread use and advantages in various industries and applications. The constant demand for high quality products and services requires companies to minimize their manufacturing costs, and delivery time in order to compete in general and niche marketplaces. Advanced manufacturing methods aim to provide economical methods of mold production. Creation of molding and tooling options for advanced composites encompasses a large portion of the fabrication time, making it a costly process and restraining factor. This research discusses a preliminary investigation into the use of soluble polymer compounds and additive manufacturing to fabricate soluble molds. These molds suffer from dimensional errors due to several factors, which have also been characterized. The basic soluble mold of a composite is 3D printed to meet the desired dimensions and geometry of holistic structures or spliced components. The time taken to dissolve the mold depends on the rate of agitation of the solvent. This process is steered towards enabling the implantation of optoelectronic devices within the composite to provide sensing capability for structural health monitoring. The shape deviation of the 3D printed mold is also studied and compared to its original dimensions to optimize the dimensional quality to produce dimensionally accurate parts. Mechanical tests were performed on compact tension (CT) resin samples prepared from these 3D printed molds and revealed crack propagation towards an embedded intact optical fiber.

  17. Cyanate ester-nanoparticle composites as multifunctional structural capacitors (United States)

    De Leon, J. Eliseo

    An important goal of engineering is to increase the energy density of electrical energy storage devices used to deliver power onboard mobile platforms. Equally important is the goal to reduce the overall mass of the vehicles transporting these devices to achieve increased fuel and cost efficiency. One approach to meeting both these objectives is to develop multifunctional systems that serve as both energy storage and load bearing structural devices. Multifunctional devices consist of constituents that individually perform a subset of the overall desired functions. However, the synergy achieved by the combination of each constituent's characteristics allows for system-level benefits that cannot be achieved by simply optimizing the separate subsystems. We investigated multifunctional systems consisting of light weight polymer matrix and high dielectric constant fillers to achieve these objectives. The monomer of bisphenol E cyanate ester exhibited excellent processing ability because of its low room temperature viscosity. Additionally, the fully cured thermoset demonstrated excellent thermal stability, specific strength and stiffness. Fillers, including multi-walled carbon nanotubes, nanometer scale barium titanate and nanometer scale calcium copper titanate, offer high dielectric constants that raised the effective dielectric constant of the polymer matrix composite. The combination of high epsilon'and high dielectric strength produce high energy density components exhibiting increased electrical energy storage. Mechanical (load bearing) improvements of the PMCs were attributed to covalently bonded nanometer and micrometer sized filler particles, as well as the continuous glass fiber, integrated into the resin systems which increased the structural characteristics of the cured composites. Breakdown voltage tests and dynamic mechanical analysis were employed to demonstrate that precise combinations of these constituents, under the proper processing conditions, can

  18. Building Block Approach' for Structural Analysis of Thermoplastic Composite Components for Automotive Applications (United States)

    Carello, M.; Amirth, N.; Airale, A. G.; Monti, M.; Romeo, A.


    Advanced thermoplastic prepreg composite materials stand out with regard to their ability to allow complex designs with high specific strength and stiffness. This makes them an excellent choice for lightweight automotive components to reduce mass and increase fuel efficiency, while maintaining the functionality of traditional thermosetting prepreg (and mechanical characteristics) and with a production cycle time and recyclability suited to mass production manufacturing. Currently, the aerospace and automotive sectors struggle to carry out accurate Finite Elements (FE) component analyses and in some cases are unable to validate the obtained results. In this study, structural Finite Elements Analysis (FEA) has been done on a thermoplastic fiber reinforced component designed and manufactured through an integrated injection molding process, which consists in thermoforming the prepreg laminate and overmolding the other parts. This process is usually referred to as hybrid molding, and has the provision to reinforce the zones subjected to additional stresses with thermoformed themoplastic prepreg as required and overmolded with a shortfiber thermoplastic resin in single process. This paper aims to establish an accurate predictive model on a rational basis and an innovative methodology for the structural analysis of thermoplastic composite components by comparison with the experimental tests results.

  19. Advances in structural mechanics of Chinese ancient architectures

    Institute of Scientific and Technical Information of China (English)

    Maohong YU; Yoshiya ODA; Dongping FANG; Junhai ZHAO


    Chinese ancient architectures are valuable heritage of ancient culture of China. Many historical building have been preserved up to now. The researches on the structural mechanics of ancient architectures show the different aspects of structure and mechanics. Systematical studies on the structural mechanics of ancient architectures have been carried out at Xi'an Jiaotong University since 1982. It is related with the need of repair of some national preservation relics in Xi'an. These studies include: 1) Ancient wooden structures including three national preservation relics Arrow Tower at North City Gate, City Tower at East City Gate, and Baogao Temple in Ningbao, Zhejiang province. 2) Ancient tall masonry building, the Big Goose Pagoda and Small Goose Pagoda in Xi'an. 3) Mechanical characteristics of ancient soil under foundation and city wall; the influence of caves in and under the ancient City Wall on the stability of the wall. 4) The typical Chinese ancient building at the center of city: the Bell Tower and Drum tower. 5) The behavior of Dou-Gong and Joggle joint of Chinese ancient wooden structure. 6) The mechanical behavior of ancient soils under complex stress state. A new systematical strength theory, the unified strength theory, is used to analyze the stability of ancient city wall in Xi'an and foundation of tall pagoda built in Tang dynasty. These researches also concern differential settlements of Arrow Tower and resistance to earthquake of these historical architecture heritages. Some other studies are also introduced. This paper gives a summary of these researches. Preservation and research are nowadays an essential requirement for the famous monuments, buildings, towers and others. Our society is more and more conscious of this necessity, which involves increasing activities of restoration, and then sometimes also of repair, mechanical strengthening and seismic retrofitting. Many historical buildings have in fact problems of structural strength and

  20. Thermal and compositional structure of the upper mantle (United States)

    Gilbert, Hersh Joseph

    Constraints for models of the convective, thermal, and mineralogical structure within the mantle depend heavily on seismic observations of the deep, and otherwise inaccessible, Earth. Studies presented within this dissertation focus primarily on the upper mantle discontinuities that bound the transition zone between the upper and lower mantle at the nominal depths of 410 and 660 km. These discontinuities are attributed to phase transitions of the mantle mineral olivine to denser configurations. Additionally, they may demark compositional layers within the mantle. This region figures prominently in the convective style of the planet. I address the questions of whether the 660-km discontinuity in some way inhibits flow from crossing between the upper and lower mantle and, more specifically, if it coincides with a compositional barrier in the mantle. Thermal variations associated with warm-rising and cool-sinking material in the mantle produce observable variations in the depths of the discontinuities. If rising or sinking materials cross the entire extent of the mantle, then the transition zone should respond to its associated thermal perturbations in a correlated manner. If instead, convection were divided between the upper and lower mantle, then thermal perturbations in the transition zone need not be spatially correlated. Observations presented in this dissertation display regions in which both the 410- and 660-km discontinuities possess greater than 20 km of peak-to-peak topography that is not correlated between the two. Studying the upper mantle below the western United States, I find no correlation between the upper mantle and the surface tectonics of the region. The topography on both discontinuities in this region is nearly as pronounced as that found where the cold subducting Tonga slab interacts with the upper mantle, suggesting the presence of a similar thermal anomaly. Additionally, amplitudes of the velocity jumps associated with the discontinuities