WorldWideScience

Sample records for internal structure composition

  1. Atomic structures and compositions of internal interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Seidman, D.N. (Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering); Merkle, K.L. (Argonne National Lab., IL (United States))

    1992-03-01

    This research program addresses fundamental questions concerning the relationships between atomic structures and chemical compositions of metal/ceramic heterophase interfaces. The chemical composition profile across a Cu/MgO {l brace}111{r brace}-type heterophase interface, produced by the internal oxidation of a Cu(Mg) single phase alloy, is measured via atom-probe field-ion microscopy with a spatial resolution of 0.121 nm; this resolution is equal to the interplanar space of the {l brace}222{r brace} MgO planes. In particular, we demonstrate for the first time that the bonding across a Cu/MgO {l brace}111{r brace}-type heterophase interface, along a <111> direction common to both the Cu matrix and an MgO precipitate, has the sequence Cu{vert bar}O{vert bar}Mg{hor ellipsis} and not Cu{vert bar}Mg{vert bar}O{hor ellipsis}; this result is achieved without any deconvolution of the experimental data. Before determining this chemical sequence it was established, via high resolution electron microscopy, that the morphology of an MgO precipitate in a Cu matrix is an octahedron faceted on {l brace}111{r brace} planes with a cube-on-cube relationship between a precipitate and the matrix. First results are also presented for the Ni/Cr{sub 2}O{sub 4} interface; for this system selected area atom probe microscopy was used to analyze this interface; Cr{sub 2}O{sub 4} precipitates are located in a field-ion microscope tip and a precipitate is brought into the tip region via a highly controlled electropolishing technique.

  2. PREFACE: International Conference on Structural Nano Composites (NANOSTRUC 2012)

    Science.gov (United States)

    Njuguna, James

    2012-09-01

    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.

  3. The Evolution and Internal Structure of Jupiter and Saturn with Compositional Gradients

    NARCIS (Netherlands)

    Vazan, A.; Helled, R.; Podolak, M.; Kovetz, A.

    2016-01-01

    The internal structure of gas giant planets may be more complex than the commonly assumed core-envelope structure with an adiabatic temperature profile. Different primordial internal structures as well as various physical processes can lead to non-homogenous compositional distributions. A

  4. Atomic structures and compositions of internal interfaces. Progress report, September 1, 1991--August 31, 1992

    Energy Technology Data Exchange (ETDEWEB)

    Seidman, D.N. [Northwestern Univ., Evanston, IL (United States). Dept. of Materials Science and Engineering; Merkle, K.L. [Argonne National Lab., IL (United States)

    1992-03-01

    This research program addresses fundamental questions concerning the relationships between atomic structures and chemical compositions of metal/ceramic heterophase interfaces. The chemical composition profile across a Cu/MgO {l_brace}111{r_brace}-type heterophase interface, produced by the internal oxidation of a Cu(Mg) single phase alloy, is measured via atom-probe field-ion microscopy with a spatial resolution of 0.121 nm; this resolution is equal to the interplanar space of the {l_brace}222{r_brace} MgO planes. In particular, we demonstrate for the first time that the bonding across a Cu/MgO {l_brace}111{r_brace}-type heterophase interface, along a <111> direction common to both the Cu matrix and an MgO precipitate, has the sequence Cu{vert_bar}O{vert_bar}Mg{hor_ellipsis} and not Cu{vert_bar}Mg{vert_bar}O{hor_ellipsis}; this result is achieved without any deconvolution of the experimental data. Before determining this chemical sequence it was established, via high resolution electron microscopy, that the morphology of an MgO precipitate in a Cu matrix is an octahedron faceted on {l_brace}111{r_brace} planes with a cube-on-cube relationship between a precipitate and the matrix. First results are also presented for the Ni/Cr{sub 2}O{sub 4} interface; for this system selected area atom probe microscopy was used to analyze this interface; Cr{sub 2}O{sub 4} precipitates are located in a field-ion microscope tip and a precipitate is brought into the tip region via a highly controlled electropolishing technique.

  5. Self-Supporting Nanoclay as Internal Scaffold Material for Direct Printing of Soft Hydrogel Composite Structures in Air.

    Science.gov (United States)

    Jin, Yifei; Liu, Chengcheng; Chai, Wenxuan; Compaan, Ashley; Huang, Yong

    2017-05-24

    Three dimensional (3D) bioprinting technology enables the freeform fabrication of complex constructs from various hydrogels and is receiving increasing attention in tissue engineering. The objective of this study is to develop a novel self-supporting direct hydrogel printing approach to extrude complex 3D hydrogel composite structures in air without the help of a support bath. Laponite, a member of the smectite mineral family, is investigated to serve as an internal scaffold material for the direct printing of hydrogel composite structures in air. In the proposed printing approach, due to its yield-stress property, Laponite nanoclay can be easily extruded through a nozzle as a liquid and self-supported after extrusion as a solid. Its unique crystal structure with positive and negative charges enables it to be mixed with many chemically and physically cross-linked hydrogels, which makes it an ideal internal scaffold material for the fabrication of various hydrogel structures. By mixing Laponite nanoclay with various hydrogel precursors, the hydrogel composites retain their self-supporting capacity and can be printed into 3D structures directly in air and retain their shapes before cross-linking. Then, the whole structures are solidified in situ by applying suitable cross-linking stimuli. The addition of Laponite nanoclay can effectively improve the mechanical and biological properties of hydrogel composites. Specifically, the addition of Laponite nanoclay results in a significant increase in the Young's modulus of each hydrogel-Laponite composite: 1.9-fold increase for the poly(ethylene glycol) diacrylate (PEGDA)-Laponite composite, 7.4-fold increase for the alginate-Laponite composite, and 3.3-fold increase for the gelatin-Laponite composite.

  6. Preface: 2nd International Conference on Structural Nano Composites (NANOSTRUC2014)

    International Nuclear Information System (INIS)

    Njuguna, J; Verdejo, R

    2014-01-01

    The NANOSTRUC 2014 took place at CSIC, Madrid, Spain. The conference theme on 'Nanosciences and Nanotechnologies – Recent Advances towards Nanoproducts and Applications'. The conference aimed 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 conferences 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

  7. Influence of electron irradiation on internal friction and structure evolution of polymer composites

    International Nuclear Information System (INIS)

    Ismailova, G.A.

    2007-01-01

    Full text: Important qualitative information on structural evolution and radiation alterations in polymer materials under the action of ionizing radiation can be obtained from the analysis of the temperature dependences of internal friction. Changing of internal friction parameters of relax maxima during irradiation is qualitative degree parameter of radiation scission-cross linking of the polymer molecules. In this work, the general phenomenological approach is realized by introduction of the effective 'observed' parameters into the simple kinetic equations. The applicability of such approach is justified by the fact that kinetics of both internal friction and scission-cross linking processes can be characterized by the same effective parameters. Temperature dependences of internal friction are experimentally studied in epoxy irradiated by 2.5 MeV pulse electron beam to different doses (D=3 MGy, 6 MGy and 9 MGy). Time dependences of internal friction characteristics associated with radiation-induced processes of polymer scission and cross-linking are analyzed and discussed. Experimental data on kinetics of structural transformations in epoxy are interpreted on the base of analytical solutions of differential equations for free radical accumulation during and after irradiation subject to the arbitrary effective order of radical recombination. It is shown that in the range of doses and dose rates under study radiation-induced scission predominates during polymer irradiation but in a certain period of time after irradiation scission changes to cross-linking. Characteristics of the kinetic curves obtained essentially depend on the dose

  8. Composite Structures Manufacturing Facility

    Data.gov (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...

  9. Grain boundaries of nanocrystalline materials - their widths, compositions, and internal structures

    International Nuclear Information System (INIS)

    Fultz, B.; Frase, H.N.

    2000-01-01

    Nanocrystalline materials contain many atoms at and near grain boundaries. Sufficient numbers of Moessbauer probe atoms can be situated in grain boundary environments to make a clear contribution to the measured Moessbauer spectrum. Three types of measurements on nanocrystalline materials are reported here, all using Moessbauer spectrometry in conjunction with X-ray diffractometry, transmission electron microscopy, or small angle neutron scattering. By measuring the fraction of atoms contributing to the grain boundary component in a Moessbauer spectrum, and by knowing the grain size of the material, it is possible to deduce the average width of grain boundaries in metallic alloys. It is found that these widths are approximately 0.5 nm for fcc alloys and slightly larger than 1.0 nm for bcc alloys.Chemical segregation to grain boundaries can be measured by Moessbauer spectrometry, especially in conjunction with small angle neutron scattering. Such measurements on Fe-Cu and Fe 3 Si-Nb were used to study how nanocrystalline materials could be stabilized against grain growth by the segregation of Cu and Nb to grain boundaries. The segregation of Cu to grain boundaries did not stabilize the Fe-Cu alloys against grain growth, since the grain boundaries were found to widen and accept more Cu atoms during annealing. The Nb additions to Fe 3 Si did suppress grain growth, perhaps because of the low mobility of Nb atoms, but also perhaps because Nb atoms altered the chemical ordering in the alloy.The internal structure of grain boundaries in nanocrystalline materials prepared by high-energy ball milling is found to be unstable against internal relaxations at low temperatures. The Moessbauer spectra of the nanocrystalline samples showed changes in the hyperfine fields attributable to movements of grain boundary atoms. In conjunction with SANS measurements, the changes in grain boundary structure induced by cryogenic exposure and annealing at low temperature were found to be

  10. Material toughness, internal structure, and caldera-collapse frequencies in basaltic and composite edifices

    Energy Technology Data Exchange (ETDEWEB)

    Gudmundsson, Agust [Department of Earth Sciences, Queen' s Building, Royal Holloway University of London, Egham TW20 OEX (United Kingdom)], E-mail: a.gudmundsson@es.rhul.ac.uk

    2008-10-01

    Formation of, and slip on existing, collapse calderas is much more common in basaltic edifices than in composite edifices. I suggest that this difference is partly due to the composite edifices being tougher and more resistant to ring-fault formation than a basaltic edifices. The high matieral toughness of composite edifices is related to their being composed of rock layers with widely different elastic properties, the elastic mismatch promoting deflection and/or arrest of potential ring faults at layer contacts.

  11. Use of SiCf/SiC ceramic composites as structure material of a fusion reactor toroid internal components

    International Nuclear Information System (INIS)

    Aiello, G.

    2001-01-01

    The use of low neutron-induced activation structural materials seems necessary in order to improve safety in future fusion power reactors. Among them, SiC f /SiC composites appear as a very promising solution because of their low activation characteristics coupled with excellent mechanical properties at high temperatures. With the main objective of evaluating the limit of present-day composites, a tritium breeding blanket using SiC f /SiC as structural material (the TAURO blanket) has been developed in the last years by the Commissariat a l'Energie Atomique (CEA). The purpose of this thesis was to modify the available design tools (computer codes, design criteria), normally used for the analyses of metallic structures, in order to better take into account the mechanical behaviour of SiC f /SiC. Alter a preliminary improvement of the calculation methods, two main topics of study could be identified: the modelling of the mechanical behaviour of the composite and the assessment of appropriate design criteria. The different behavioural models available in literature were analysed in order to find the one that was the best suited to the specific problems met in the field of fusion power. The selected model was then implemented in the finite elements code CASTEM 2000 used within the CEA for the thermo-mechanical analyses of the TAURO blanket. For the design of the blanket, we proposed a new resistance criterion whose main advantage, with respect to the other examined, lies in the easiness of identification. The suggested solutions were then applied in the design studies of the TAURO blanket. We then could show that the use of appropriate calculation methodologies is necessary in order to achieve a correct design of the blanket and a more realistic estimate of the limits of present day composites. The obtained results can also be extended to all nuclear components making use of SiC f /SiC structures. (author) [fr

  12. Process Modelling of Curing Process-Induced Internal Stress and Deformation of Composite Laminate Structure with Elastic and Viscoelastic Models

    Science.gov (United States)

    Li, Dongna; Li, Xudong; Dai, Jianfeng

    2018-06-01

    In this paper, two kinds of transient models, the viscoelastic model and the linear elastic model, are established to analyze the curing deformation of the thermosetting resin composites, and are calculated by COMSOL Multiphysics software. The two models consider the complicated coupling between physical and chemical changes during curing process of the composites and the time-variant characteristic of material performance parameters. Subsequently, the two proposed models are implemented respectively in a three-dimensional composite laminate structure, and a simple and convenient method of local coordinate system is used to calculate the development of residual stresses, curing shrinkage and curing deformation for the composite laminate. Researches show that the temperature, degree of curing (DOC) and residual stresses during curing process are consistent with the study in literature, so the curing shrinkage and curing deformation obtained on these basis have a certain referential value. Compared the differences between the two numerical results, it indicates that the residual stress and deformation calculated by the viscoelastic model are more close to the reference value than the linear elastic model.

  13. Size-confined fixed-composition and composition-dependent engineered band gap alloying induces different internal structures in L-cysteine-capped alloyed quaternary CdZnTeS quantum dots

    Science.gov (United States)

    Adegoke, Oluwasesan; Park, Enoch Y.

    2016-06-01

    The development of alloyed quantum dot (QD) nanocrystals with attractive optical properties for a wide array of chemical and biological applications is a growing research field. In this work, size-tunable engineered band gap composition-dependent alloying and fixed-composition alloying were employed to fabricate new L-cysteine-capped alloyed quaternary CdZnTeS QDs exhibiting different internal structures. Lattice parameters simulated based on powder X-ray diffraction (PXRD) revealed the internal structure of the composition-dependent alloyed CdxZnyTeS QDs to have a gradient nature, whereas the fixed-composition alloyed QDs exhibited a homogenous internal structure. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis confirmed the size-confined nature and monodispersity of the alloyed nanocrystals. The zeta potential values were within the accepted range of colloidal stability. Circular dichroism (CD) analysis showed that the surface-capped L-cysteine ligand induced electronic and conformational chiroptical changes in the alloyed nanocrystals. The photoluminescence (PL) quantum yield (QY) values of the gradient alloyed QDs were 27-61%, whereas for the homogenous alloyed QDs, the PL QY values were spectacularly high (72-93%). Our work demonstrates that engineered fixed alloying produces homogenous QD nanocrystals with higher PL QY than composition-dependent alloying.

  14. Effects of the composition and crystal structure of zinc-nickel alloy deposits on the internal strain

    Energy Technology Data Exchange (ETDEWEB)

    Tsuru, Y.; Tanaka, M. [Kyushu Inst. of Technology, Kitakyushu (Japan). Faculty of Engineering

    1996-02-05

    An average internal strain in the electrodeposited Zn-Ni alloy films was in-situ measured using the resistance wire type strain gauge setup on the reverse side of the copper substrate. The Ni content of the Zn-Ni alloy coatings utilized for the steel frame of automobiles and for the plastic coated steel sheets is around at 15% and the dominant structure is the {gamma}-phase. Such Zn-Ni alloy coatings are favorable for the protection of steel against corrosion. The internal stress in these deposits is always compressive during electroplating. However, upon turning off the current, the internal stress sharply changes from compressive to tensile. The tensile stress seems to simultaneously result in many cracks on the surface of the deposits. In this study, a resistance wire type strain gauge meter was used for successive measurement of the internal strain in the deposits during electroplating and solid-state stripping voltammetry was applied for the anodic dissolution of the deposits. And the effects concerning the partial electroleaching of Zn from the deposits on the internal strain in the deposits under periodic reverse plating. 15 refs., 8 figs., 3 tabs.

  15. EDITORIAL Smart materials, multifunctional composites, and morphing structures: selected papers from the 20th International Conference on Adaptive Structures and Technologies (ICAST 2009) Smart materials, multifunctional composites, and morphing structures: selected papers from the 20th International Conference on Adaptive Structures and Technologies (ICAST 2009)

    Science.gov (United States)

    Liao, Wei-Hsin

    2010-12-01

    The 20th International Conference on Adaptive Structures and Technologies (ICAST) was held on 20-22 October 2009 in Hong Kong. This special section of Smart Materials and Structures is derived from the research papers presented at the conference. Of the 106 papers presented at the conference, 11 papers were reviewed and accepted for this special section, following the regular review procedures of the journal. This special section is focused on smart materials, multifunctional composites, and applications on morphing structures. Smart materials. Smart materials are the foundation of adaptive structures and intelligent systems. The development of new materials will lead to significant improvement in various applications. Three articles are focused on the fabrication of new materials and investigation of their behaviors: Barium strontium zirconate titanate ((Ba1-xSrx)(ZrxTi1-x)O3; BSZT, x = 0.25 and 0.75) ceramics with a highly crystalline structure were fabricated using the combustion technique. The microstructure of BSZT powders exhibited an almost-spherical morphology and had a porous agglomerated form. Polyaniline (PANI)/clay nanoparticles with unique core-shell structure were synthesized via Pickering emulsion polymerization. By dispersing PANI/clay nanoparticles in silicone oil, the ER fluid was made. Magnetic field effects were investigated on the deposition rate and surface morphology of chromium nitride coatings deposited by magnetron sputtering for superior hardness, excellent wear and oxidation resistance. The surface morphology of chromium nitride films was also examined by a scanning electron microscope (SEM). Multifunctional composites. Composites are made from two or more constituent materials so they can combine the best properties of different materials. Five papers deal with fabrication, testing, and modeling of various multifunctional composites: A new active structural fiber (ASF) was fabricated by coating a single carbon fiber with a concentric

  16. Heterogeneous dissipative composite structures

    Science.gov (United States)

    Ryabov, Victor; Yartsev, Boris; Parshina, Ludmila

    2018-05-01

    The paper suggests mathematical models of decaying vibrations in layered anisotropic plates and orthotropic rods based on Hamilton variation principle, first-order shear deformation laminated plate theory (FSDT), as well as on the viscous-elastic correspondence principle of the linear viscoelasticity theory. In the description of the physical relationships between the materials of the layers forming stiff polymeric composites, the effect of vibration frequency and ambient temperature is assumed as negligible, whereas for the viscous-elastic polymer layer, temperature-frequency relationship of elastic dissipation and stiffness properties is considered by means of the experimentally determined generalized curves. Mitigation of Hamilton functional makes it possible to describe decaying vibration of anisotropic structures by an algebraic problem of complex eigenvalues. The system of algebraic equation is generated through Ritz method using Legendre polynomials as coordinate functions. First, real solutions are found. To find complex natural frequencies of the system, the obtained real natural frequencies are taken as input values, and then, by means of the 3rd order iteration method, complex natural frequencies are calculated. The paper provides convergence estimates for the numerical procedures. Reliability of the obtained results is confirmed by a good correlation between analytical and experimental values of natural frequencies and loss factors in the lower vibration tones for the two series of unsupported orthotropic rods formed by stiff GRP and CRP layers and a viscoelastic polymer layer. Analysis of the numerical test data has shown the dissipation & stiffness properties of heterogeneous composite plates and rods to considerably depend on relative thickness of the viscoelastic polymer layer, orientation of stiff composite layers, vibration frequency and ambient temperature.

  17. Thermomechanics of composite structures under high temperatures

    CERN Document Server

    Dimitrienko, Yu I

    2016-01-01

    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...

  18. Radiation curable adhesive compositions and composite structures

    International Nuclear Information System (INIS)

    Brenner, W.

    1984-01-01

    This disclosure relates to novel adhesive compositions and composite structures utilizing the same, wherein said adhesive compositions contain an elastomer, a chemically compatible ethylenically unsaturated monomer, a tackifier, an adhesion promoter, and optionally, pigments, fillers, thickeners and flow control agents which are converted from the liquid to the solid state by exposure to high energy ionizing radiation such as electron beam. A particularly useful application for such adhesive compositions comprises the assembly of certain composite structures or laminates consisting of, for example, a fiber flocked rubber sheet and a metal base with the adhesive fulfilling the multiple functions of adhering the flocked fiber to the rubber sheet as well as adhering the rubber sheet to the metal base. Optionally, the rubber sheet itself may also be cured at the same time as the adhesive composition with all operations being carried out at ambient temperatures and in the presence of air, with exposure of said assembly to selected dosages of high energy ionizing radiation. These adhesive compositions contain no solvents thereby almost eliminating air pollution or solvent toxicity problems, and offer substantial savings in energy and labor as they are capable of curing in very short time periods without the use of external heat which might damage the substrate

  19. Composite materials for aircraft structures

    National Research Council Canada - National Science Library

    Baker, A. A; Dutton, Stuart; Kelly, Donald

    2004-01-01

    ... materials for aircraft structures / Alan Baker, Stuart Dutton, and Donald Kelly- 2nd ed. p. cm. - (Education series) Rev. ed. of: Composite materials for aircraft structures / edited by B. C. Hos...

  20. Combustible structural composites and methods of forming combustible structural composites

    Science.gov (United States)

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

    2013-04-02

    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.

  1. Advanced technology composite aircraft structures

    Science.gov (United States)

    Ilcewicz, Larry B.; Walker, Thomas H.

    1991-01-01

    Work performed during the 25th month on NAS1-18889, Advanced Technology Composite Aircraft Structures, is summarized. The main objective of this program is to develop an integrated technology and demonstrate a confidence level that permits the cost- and weight-effective use of advanced composite materials in primary structures of future aircraft with the emphasis on pressurized fuselages. The period from 1-31 May 1991 is covered.

  2. Deformation Characteristics of Composite Structures

    Directory of Open Access Journals (Sweden)

    Theddeus T. AKANO

    2016-08-01

    Full Text Available The composites provide design flexibility because many of them can be moulded into complex shapes. The carbon fibre-reinforced epoxy composites exhibit excellent fatigue tolerance and high specific strength and stiffness which have led to numerous advanced applications ranging from the military and civil aircraft structures to the consumer products. However, the modelling of the beams undergoing the arbitrarily large displacements and rotations, but small strains, is a common problem in the application of these engineering composite systems. This paper presents a nonlinear finite element model which is able to estimate the deformations of the fibre-reinforced epoxy composite beams. The governing equations are based on the Euler-Bernoulli beam theory (EBBT with a von Kármán type of kinematic nonlinearity. The anisotropic elasticity is employed for the material model of the composite material. Moreover, the characterization of the mechanical properties of the composite material is achieved through a tensile test, while a simple laboratory experiment is used to validate the model. The results reveal that the composite fibre orientation, the type of applied load and boundary condition, affect the deformation characteristics of the composite structures. The nonlinearity is an important factor that should be taken into consideration in the analysis of the fibre-reinforced epoxy composites.

  3. Optimization of Laminated Composite Structures

    DEFF Research Database (Denmark)

    Henrichsen, Søren Randrup

    of the contributions of the PhD project are included in the second part of the thesis. Paper A presents a framework for free material optimization where commercially available finite element analysis software is used as analysis tool. Robust buckling optimization of laminated composite structures by including...... 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...... nonlinear analysis of structures, buckling and post-buckling analysis of structures, and formulations for optimization of structures considering stiffness, buckling, and post-buckling criteria. Lastly, descriptions, main findings, and conclusions of the papers are presented. The papers forming the basis...

  4. Advanced composite structures. [metal matrix composites - structural design criteria for spacecraft construction materials

    Science.gov (United States)

    1974-01-01

    A monograph is presented which establishes structural design criteria and recommends practices to ensure the design of sound composite structures, including composite-reinforced metal structures. (It does not discuss design criteria for fiber-glass composites and such advanced composite materials as beryllium wire or sapphire whiskers in a matrix material.) Although the criteria were developed for aircraft applications, they are general enough to be applicable to space vehicles and missiles as well. The monograph covers four broad areas: (1) materials, (2) design, (3) fracture control, and (4) design verification. The materials portion deals with such subjects as material system design, material design levels, and material characterization. The design portion includes panel, shell, and joint design, applied loads, internal loads, design factors, reliability, and maintainability. Fracture control includes such items as stress concentrations, service-life philosophy, and the management plan for control of fracture-related aspects of structural design using composite materials. Design verification discusses ways to prove flightworthiness.

  5. Hydrodynamic Forces on Composite Structures

    Science.gov (United States)

    2014-06-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited HYDRODYNAMIC ...Thesis 4. TITLE AND SUBTITLE HYDRODYNAMIC FORCES ON COMPOSITE STRUCTURES 5. FUNDING NUMBERS 6. AUTHOR(S) Scott C. Millhouse 7. PERFORMING...angles yields different free surface effects including vortices and the onset of cavitation . 14. SUBJECT TERMS Fluid structure interaction, FSI, finite

  6. Structural biological composites: An overview

    Science.gov (United States)

    Meyers, Marc A.; Lin, Albert Y. M.; Seki, Yasuaki; Chen, Po-Yu; Kad, Bimal K.; Bodde, Sara

    2006-07-01

    Biological materials are complex composites that are hierarchically structured and multifunctional. Their mechanical properties are often outstanding, considering the weak constituents from which they are assembled. They are for the most part composed of brittle (often, mineral) and ductile (organic) components. These complex structures, which have risen from millions of years of evolution, are inspiring materials scientists in the design of novel materials. This paper discusses the overall design principles in biological structural composites and illustrates them for five examples; sea spicules, the abalone shell, the conch shell, the toucan and hornbill beaks, and the sheep crab exoskeleton.

  7. Composite materials for cryogenic structures

    International Nuclear Information System (INIS)

    Kasen, M.B.

    1978-01-01

    The paper is concerned with the composition, mechanical properties and capabilities of various types of composite materials for cryogenic structures. Attention is given to high-pressure plastic laminates, low-pressure plastic laminates, metal-matrix laminates, and aggregates (low-temperature concretes). The ability of these materials to match the strength and modulus of stainless steels suggests that their usage will substantially increase as alloying elements become scarce and more expensive

  8. Commercial transport aircraft composite structures

    Science.gov (United States)

    Mccarty, J. E.

    1983-01-01

    The role that analysis plays in the development, production, and substantiation of aircraft structures is discussed. The types, elements, and applications of failure that are used and needed; the current application of analysis methods to commercial aircraft advanced composite structures, along with a projection of future needs; and some personal thoughts on analysis development goals and the elements of an approach to analysis development are discussed.

  9. Internal spin structure of the nucleon

    International Nuclear Information System (INIS)

    Hughes, V.W.; Kuti, J.

    1983-01-01

    The study of the structure of the proton and neutron through deep inelastic scattering, initially with electrons but subsequently with muons and neutrinos as well, has played a central role in establishing the quark-parton theory of the composition of hadrons and of quantum chromodynamics (QCD). One important aspect of these theoretical and experimental developments is the two spin-dependent structure functions, which are independent of the two spin-averaged structure functions and define the internal spin structure of the nucleon. Since both quarks and gluons possess spin and the forces between them are spin dependent, we can expect important information on these forces and on nucleon structure to be obtained through the study of the spindependent aspects of the nucleon wave function, as has been the case before in atomic and nuclear physics

  10. Impact source localisation in aerospace composite structures

    Science.gov (United States)

    De Simone, Mario Emanuele; Ciampa, Francesco; Boccardi, Salvatore; Meo, Michele

    2017-12-01

    The most commonly encountered type of damage in aircraft composite structures is caused by low-velocity impacts due to foreign objects such as hail stones, tool drops and bird strikes. Often these events can cause severe internal material damage that is difficult to detect and may lead to a significant reduction of the structure’s strength and fatigue life. For this reason there is an urgent need to develop structural health monitoring systems able to localise low-velocity impacts in both metallic and composite components as they occur. This article proposes a novel monitoring system for impact localisation in aluminium and composite structures, which is able to determine the impact location in real-time without a-priori knowledge of the mechanical properties of the material. This method relies on an optimal configuration of receiving sensors, which allows linearization of well-known nonlinear systems of equations for the estimation of the impact location. The proposed algorithm is based on the time of arrival identification of the elastic waves generated by the impact source using the Akaike Information Criterion. The proposed approach was demonstrated successfully on both isotropic and orthotropic materials by using a network of closely spaced surface-bonded piezoelectric transducers. The results obtained show the validity of the proposed algorithm, since the impact sources were detected with a high level of accuracy. The proposed impact detection system overcomes current limitations of other methods and can be retrofitted easily on existing aerospace structures allowing timely detection of an impact event.

  11. Internal structure of magnetic endosomes

    Science.gov (United States)

    Rivière, C.; Wilhelm, C.; Cousin, F.; Dupuis, V.; Gazeau, F.; Perzynski, R.

    2007-01-01

    The internal structure of biological vesicles filled with magnetic nanoparticles is investigated using the following complementary analyses: electronic transmission microscopy, dynamic probing by magneto-optical birefringence and structural probing by Small Angle Neutron Scattering (SANS). These magnetic vesicles are magnetic endosomes obtained via a non-specific interaction between cells and anionic magnetic iron oxide nanoparticles. Thanks to a magnetic purification process, they are probed at two different stages of their formation within HeLa cells: (i) adsorption of nanoparticles onto the cellular membrane and (ii) their subsequent internalisation within endosomes. Differences in the microenvironment of the magnetic nanoparticles at those two different stages are highlighted here. The dynamics of magnetic nanoparticles adsorbed onto cellular membranes and confined within endosomes is respectively 3 and 5 orders of magnitude slower than for isolated magnetic nanoparticles in aqueous media. Interestingly, SANS experiments show that magnetic endosomes have an internal structure close to decorated vesicles, with magnetic nanoparticles locally decorating the endosome membrane, inside their inner-sphere. These results, important for future biomedical applications, suggest that multiple fusions of decorated vesicles are the biological processes underlying the endocytosis of that kind of nanometric materials.

  12. Structural Health Monitoring: Numerical Damage Predictor for Composite Structures

    National Research Council Canada - National Science Library

    Lannamann, Daniel

    2001-01-01

    .... Wide use of composites is found in aircraft, armored vehicles, ships and civil structures This present research demonstrates the ability to numerically detect damage in a composite sandwich structure...

  13. Internal structure of black holes

    International Nuclear Information System (INIS)

    Cvetic, Mirjam

    2013-01-01

    Full text: We review recent progress that sheds light on the internal structure of general black holes. We first summarize properties of general multi-charged rotating black holes both in four and five dimensions. We show that the asymptotic boundary conditions of these general asymptotically flat black holes can be modified such that a conformal symmetry emerges. These subtracted geometries preserve the thermodynamic properties of the original black holes and are of the Lifshitz type, thus describing 'a black hole in the asymptotically conical box'. Recent efforts employ solution generating techniques to construct interpolating geometries between the original black hole and their subtracted geometries. Upon lift to one dimension higher, these geometries lift to AdS 3 times a sphere, and thus provide a microscopic interpretation of the black hole entropy in terms of dual two-dimensional conformal field theory. (author)

  14. Inside-Out Manufacturing of Composite Structures

    Data.gov (United States)

    National Aeronautics and Space Administration — Tooling for the manufacture of large structures from composite materials often costs much more than individual parts, rendering the processes unattractive for...

  15. Spinor Structure and Internal Symmetries

    Science.gov (United States)

    Varlamov, V. V.

    2015-10-01

    Spinor structure and internal symmetries are considered within one theoretical framework based on the generalized spin and abstract Hilbert space. Complex momentum is understood as a generating kernel of the underlying spinor structure. It is shown that tensor products of biquaternion algebras are associated with the each irreducible representation of the Lorentz group. Space-time discrete symmetries P, T and their combination PT are generated by the fundamental automorphisms of this algebraic background (Clifford algebras). Charge conjugation C is presented by a pseudoautomorphism of the complex Clifford algebra. This description of the operation C allows one to distinguish charged and neutral particles including particle-antiparticle interchange and truly neutral particles. Spin and charge multiplets, based on the interlocking representations of the Lorentz group, are introduced. A central point of the work is a correspondence between Wigner definition of elementary particle as an irreducible representation of the Poincaré group and SU(3)-description (quark scheme) of the particle as a vector of the supermultiplet (irreducible representation of SU(3)). This correspondence is realized on the ground of a spin-charge Hilbert space. Basic hadron supermultiplets of SU(3)-theory (baryon octet and two meson octets) are studied in this framework. It is shown that quark phenomenologies are naturally incorporated into presented scheme. The relationship between mass and spin is established. The introduced spin-mass formula and its combination with Gell-Mann-Okubo mass formula allows one to take a new look at the problem of mass spectrum of elementary particles.

  16. Impact analysis of composite aircraft structures

    Science.gov (United States)

    Pifko, Allan B.; Kushner, Alan S.

    1993-01-01

    The impact analysis of composite aircraft structures is discussed. Topics discussed include: background remarks on aircraft crashworthiness; comments on modeling strategies for crashworthiness simulation; initial study of simulation of progressive failure of an aircraft component constructed of composite material; and research direction in composite characterization for impact analysis.

  17. Composite Dry Structure Cost Improvement Approach

    Science.gov (United States)

    Nettles, Alan; Nettles, Mindy

    2015-01-01

    This effort demonstrates that by focusing only on properties of relevance, composite interstage and shroud structures can be placed on the Space Launch System vehicle that simultaneously reduces cost, improves reliability, and maximizes performance, thus providing the Advanced Development Group with a new methodology of how to utilize composites to reduce weight for composite structures on launch vehicles. Interstage and shroud structures were chosen since both of these structures are simple in configuration and do not experience extreme environments (such as cryogenic or hot gas temperatures) and should represent a good starting point for flying composites on a 'man-rated' vehicle. They are used as an example only. The project involves using polymer matrix composites for launch vehicle structures, and the logic and rationale behind the proposed new methodology.

  18. Multi-functional composite structures

    Science.gov (United States)

    Mulligan, Anthony C.; Halloran, John; Popovich, Dragan; Rigali, Mark J.; Sutaria, Manish P.; Vaidyanathan, K. Ranji; Fulcher, Michael L.; Knittel, Kenneth L.

    2004-10-19

    Fibrous monolith processing techniques to fabricate multifunctional structures capable of performing more than one discrete function such as structures capable of bearing structural loads and mechanical stresses in service and also capable of performing at least one additional non-structural function.

  19. 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

    2013-07-01

    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.

  20. Market structures in international telecommunications

    DEFF Research Database (Denmark)

    Henten, Anders

    1998-01-01

    Paper dealing with the internationalisation of telecommunications and the developing market structures.......Paper dealing with the internationalisation of telecommunications and the developing market structures....

  1. Forming of shape memory composite structures

    DEFF Research Database (Denmark)

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

    2013-01-01

    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...... of a two-layer unidirectional thermoplastic composite (glass filled polypropylene). Skins were joined to the foamed core by hot compression without any adhesive: a very good adhesion was obtained as experimental tests confirmed. The structure of the foam core was investigated by means of computer axial...... tomography. Final shape memory composite panels were mechanically tested by three point bending before and after a shape memory step. This step consisted of a compression to reduce the panel thickness up to 60%. At the end of the bending test the panel shape was recovered by heating and a new memory step...

  2. Mechanical Model Development for Composite Structural Supercapacitors

    Science.gov (United States)

    Ricks, Trenton M.; Lacy, Thomas E., Jr.; Santiago, Diana; Bednarcyk, Brett A.

    2016-01-01

    Novel composite structural supercapacitor concepts have recently been developed as a means both to store electrical charge and to provide modest mechanical load carrying capability. Double-layer composite supercapacitors are often fabricated by impregnating a woven carbon fiber fabric, which serves as the electrodes, with a structural polymer electrolyte. Polypropylene or a glass fabric is often used as the separator material. Recent research has been primarily limited to evaluating these composites experimentally. In this study, mechanical models based on the Multiscale Generalized Method of Cells (MSGMC) were developed and used to calculate the shear and tensile properties and response of two composite structural supercapacitors from the literature. The modeling approach was first validated against traditional composite laminate data. MSGMC models for composite supercapacitors were developed, and accurate elastic shear/tensile properties were obtained. It is envisioned that further development of the models presented in this work will facilitate the design of composite components for aerospace and automotive applications and can be used to screen candidate constituent materials for inclusion in future composite structural supercapacitor concepts.

  3. Design and Processing of Structural Composite Batteries

    National Research Council Canada - National Science Library

    Wong, E. L; Baechle, D. M; Xu, K; Carter, R. H; Snyder, J. F; Wetzel, E. D

    2007-01-01

    ...) 2007 Symposium and Exhibition held in Baltimore, MD, on 3-7 June 2007. Multifunctional structural composites are being developed to simultaneously bear mechanical loads and store electrochemical energy...

  4. Vegetation composition and structure influences bird species ...

    African Journals Online (AJOL)

    Vegetation composition and structure influences bird species community ... variables on bird species diversity and richness of respective foraging guilds, and ... of the species assessed: (1) increasing closed cover due to woody plant density, ...

  5. Organizational Structures that Support Internal Program Evaluation

    Science.gov (United States)

    Lambur, Michael T.

    2008-01-01

    This chapter explores how the structure of large complex organizations such as Cooperative Extension affects their ability to support internal evaluation of their programs and activities. Following a literature review of organizational structure and its relation to internal evaluation capacity, the chapter presents the results of interviews with…

  6. High Thermal Conductivity Composite Structures

    National Research Council Canada - National Science Library

    Bootle, John

    1999-01-01

    ... applications and space based radiators. The advantage of this material compared to competing materials that it can be used to fabricate high strength, high thermal conductivity, relatively thin structures less than 0.050" thick...

  7. Composite Structure with Origami Core

    Science.gov (United States)

    2016-07-19

    spherical linkages using the mechanism theory . Precise motions of origami were identified. In the second case, we identified a link between thick panel...operating reversibly by a coupled tension-to-torsion actuation mechanism . Using theory , we quantitatively explain the complementary effects of an increase in...structures. Our research has paved the way for much broader utilization of such structures in aeronautics and aerospace industries. 15. SUBJECT TERMS

  8. Anisotropic magnetism in field-structured composites

    International Nuclear Information System (INIS)

    Martin, James E.; Venturini, Eugene; Odinek, Judy; Anderson, Robert A.

    2000-01-01

    Magnetic field-structured composites (FSCs) are made by structuring magnetic particle suspensions in uniaxial or biaxial (e.g., rotating) magnetic fields, while polymerizing the suspending resin. A uniaxial field produces chainlike particle structures, and a biaxial field produces sheetlike particle structures. In either case, these anisotropic structures affect the measured magnetic hysteresis loops, with the magnetic remanence and susceptibility increased significantly along the axis of the structuring field, and decreased slightly orthogonal to the structuring field, relative to the unstructured particle composite. The coercivity is essentially unaffected by structuring. We present data for FSCs of magnetically soft particles, and demonstrate that the altered magnetism can be accounted for by considering the large local fields that occur in FSCs. FSCs of magnetically hard particles show unexpectedly large anisotropies in the remanence, and this is due to the local field effects in combination with the large crystalline anisotropy of this material. (c) 2000 The American Physical Society

  9. Adaptive, tolerant and efficient composite structures

    CERN Document Server

    Sinapius, Michael

    2013-01-01

    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 ...

  10. Structural modeling for multicell composite rotor blades

    Science.gov (United States)

    Rehfield, Lawrence W.; Atilgan, Ali R.

    1987-01-01

    Composite material systems are currently good candidates for aerospace structures, primarily for the design flexibility they offer, i.e., it is possible to tailor the material and manufacturing approach to the application. A working definition of elastic or structural tailoring is the use of structural concept, fiber orientation, ply stacking sequence, and a blend of materials to achieve specific performance goals. In the design process, choices of materials and dimensions are made which produce specific response characteristics, and which permit the selected goals to be achieved. Common choices for tailoring goals are preventing instabilities or vibration resonances or enhancing damage tolerance. An essential, enabling factor in the design of tailored composite structures is structural modeling that accurately, but simply, characterizes response. The objective of this paper is to present a new multicell beam model for composite rotor blades and to validate predictions based on the new model by comparison with a finite element simulation in three benchmark static load cases.

  11. Impact damages modeling in laminated composite structures

    Directory of Open Access Journals (Sweden)

    Kreculj Dragan D.

    2014-01-01

    Full Text Available Laminated composites have an important application in modern engineering structures. They are characterized by extraordinary properties, such as: high strength and stiffness and lightweight. Nevertheless, a serious obstacle to more widespread use of those materials is their sensitivity to the impact loads. Impacts cause initiation and development of certain types of damages. Failures that occur in laminated composite structures can be intralaminar and interlaminar. To date it was developed a lot of simulation models for impact damages analysis in laminates. Those models can replace real and expensive testing in laminated structures with a certain accuracy. By using specialized software the damage parameters and distributions can be determined (at certain conditions on laminate structures. With performing numerical simulation of impact on composite laminates there are corresponding results valid for the analysis of these structures.

  12. Effect of barrier height and indium composition on the internal quantum efficiency of (In)AlGaN multiple quantum well structures

    Energy Technology Data Exchange (ETDEWEB)

    Ledentsov, Nikolay Jr.; Reich, Christoph; Mehnke, Frank; Kuhn, Christian; Wernicke, Tim; Kolbe, Tim; Lobo Ploch, Neysha; Rass, Jens [Institute of Solid State Physics, Technische Universitaet Berlin (Germany); Kueller, Viola [Ferdinand-Braun-Institut, Berlin (Germany); Kneissl, Michael [Institute of Solid State Physics, Technische Universitaet Berlin (Germany); Ferdinand-Braun-Institut, Berlin (Germany)

    2013-07-01

    We studied (In)AlGaN multiple quantum wells (MQWs) emitting in the UV-B spectral region with photoluminescence and electroluminescence spectroscopy. The internal quantum efficiency (IQE) was determined by temperature dependent measurements (5 K-300 K). The quantum confined Stark effect (QCSE) was investigated by studying the shift of the emission energy with increasing excitation power density. In the first series, Al{sub 0.27}Ga{sub 0.73}N MQWs with different Al{sub x}Ga{sub 1-x}N barriers (0.32

  13. Crustal structure and composition to the S of the Spanish Central System: Effect of Alpine reactivation in an internal Variscan domain

    Science.gov (United States)

    Ayarza, Puy; Carbonell, Ramón; Ehsan, Siddique; Martí, David; Palomeras, Immaculada; Martínez Poyatos, David

    2016-04-01

    The ALCUDIA Project has acquired vertical incidence and wide-angle reflection seismic data in the Variscan Central Iberian Zone of Spain. The NE-SW, ~300 km long profiles sample an area going from the suture between the Variscan Central Iberian and the Ossa-Morena Zones in the S to the boundary between the former and the Alpine Central System to the N. Although crustal thickness appears to be fairly constant along most of the Central Iberian Zone, a gradual increase of 3-5 km in the northern half of the profile is clearly imaged by the wide-angle data. This increase in the Moho depth is accompanied by a decrease in the thickness of the layered lower crust from the Toledo Anatectic Complex to the N. Right in this area, the amount of Variscan metasediments diminish and the surface geology is characterized by granites, migmatites and by the Madrid Basin, a foreland basin of the Alpine Central System that is part of the bigger Tagus Basin. The increase in crustal thickness identified in the neighborhood of the Central System is also accompanied by a slight increase in the Poisson ratio values, which even though still below 0.25, they are higher than those observed in the southern part of the profile, far from the influence of the late Variscan melting episode and of that of the Alpine tectonics. Two scenarios are considered to take part in the Moho deepening near the Central System: Firstly, the Alpine reactivation causing this mountain belt has increased the crustal load giving rise to a foreland basin and a moderate crustal thickening. Also, a gradual change in crustal composition to the N, incorporating denser and more basic rocks, might also play a role in the average crustal density and contribute to Moho deepening by isostatic readjustment. The importance of each of these process is, as yet, unknown. However, the next acquisition of the CIMDEF project wide-angle reflection dataset across the central part of the Iberian Peninsula, crossing the Central System, will

  14. Quantitative NDE of Composite Structures at NASA

    Science.gov (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.

    2015-01-01

    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.

  15. Production defects in marine composite structures

    DEFF Research Database (Denmark)

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

    2007-01-01

    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...

  16. An investigation of structural design methodology for HTGR reactor internals with ceramic materials (Contract research)

    International Nuclear Information System (INIS)

    Sumita, Junya; Shibata, Taiju; Nakagawa, Shigeaki; Iyoku, Tatsuo; Sawa, Kazuhiro

    2008-03-01

    To advance the performance and safety of HTGR, heat-resistant ceramic materials are expected to be used as reactor internals of HTGR. C/C composite and superplastic zirconia are the promising materials for this purpose. In order to use these new materials as reactor internals in HTGR, it is necessary to establish a structure design method to guarantee the structural integrity under environmental and load conditions. Therefore, C/C composite expected as reactor internals of VHTR is focused and an investigation on the structural design method applicable to the C/C composite and a basic applicability of the C/C composite to representative structures of HTGR were carried out in this report. As the results, it is found that the competing risk theory for the strength evaluation of the C/C composite is applicable to design method and C/C composite is expected to be used as reactor internals of HTGR. (author)

  17. International conference on design, fabrication and economy of metal structures

    CERN Document Server

    Farkas, József

    2013-01-01

    These are the proceedings of the International Conference on Design, Fabrication and Economy of Metal Structures held on 24-26 April 2013 in Miskolc, Hungary which contain 99 papers covering: Structural optimization Thin-walled structures Stability Fatigue Frames Fire Fabrication Welding technology Applications Steel-concrete composite Special problems The authors are from 23 different countries, ensuring that the themes covered are of worldwide interest and importance. The International Institute of Welding (IIW), the International Society of Structural and Multidisciplinary Optimization (ISSMO), the TÁMOP 4.2.1.B-10/2/KONV-2010-0001 project entitled “Increasing the quality of higher education through the development of research - development and innovation program at the University of Miskolc supported by the European Union, co-financed by the European Social Fund” and many other sponsors helped organizers to collect these valuable studies, the results of which will provoke discussion, and provide an i...

  18. Hybrid Simulation of Composite Structures

    DEFF Research Database (Denmark)

    Høgh, Jacob Herold

    experiment. The technique has primarily been used within earthquake engineering but many other fields of engineering have utilized the method with benefit. However, these previous efforts have focused on structures with a simple boundary between the numerical and physical substructure i.e. few degrees...... the transfer system and the control and monitoring techniques in the shared boundary is therefore a key issue in this type of hybrid simulation. During the research, hybrid simulation platforms have been programmed capable of running on different time scales with advanced control and monitoring techniques...

  19. Monitoring on internal temperature of composite insulator with embedding fiber Bragg grating for early diagnosis

    Science.gov (United States)

    Chen, Wen; Tang, Ming

    2017-04-01

    The abnormal temperature rise is the precursor of the defective composite insulator in power transmission line. However no consolidated techniques or methodologies can on line monitor its internal temperature now. Thus a new method using embedding fiber Bragg grating (FBG) in fiber reinforced polymer (FRP) rod is adopted to monitor its internal temperature. To correctly demodulate the internal temperature of FRP rod from the Bragg wavelength shift of FBG, the conversion coefficient between them is deduced theoretically based on comprehensive investigation on the thermal stresses of the metal-composite joint, as well as its material and structural properties. Theoretical model shows that the conversion coefficients of FBG embedded in different positions will be different because of non-uniform thermal stress distribution, which is verified by an experiment. This work lays the theoretical foundation of monitoring the internal temperature of composite insulator with embedding FBG, which is of great importance to its health structural monitoring, especially early diagnosis.

  20. Silver Matrix Composites - Structure and Properties

    Directory of Open Access Journals (Sweden)

    Wieczorek J.

    2016-03-01

    Full Text Available Phase compositions of composite materials determine their performance as well as physical and mechanical properties. Depending on the type of applied matrix and the kind, amount and morphology of the matrix reinforcement, it is possible to shape the material properties so that they meet specific operational requirements. In the paper, results of investigations on silver alloy matrix composites reinforced with ceramic particles are presented. The investigations enabled evaluation of hardness, tribological and mechanical properties as well as the structure of produced materials. The matrix of composite material was an alloy of silver and aluminium, magnesium and silicon. As the reinforcing phase, 20-60 μm ceramic particles (SiC, SiO2, Al2O3 and Cs were applied. The volume fraction of the reinforcing phase in the composites was 10%. The composites were produced using the liquid phase (casting technology, followed by plastic work (the KOBO method. The mechanical and tribological properties were analysed for plastic work-subjected composites. The mechanical properties were assessed based on a static tensile and hardness tests. The tribological properties were investigated under dry sliding conditions. The analysis of results led to determination of effects of the composite production technology on their performance. Moreover, a relationship between the type of reinforcing phase and the mechanical and tribological properties was established.

  1. Biomimetic mineral-organic composite scaffolds with controlled internal architecture.

    Science.gov (United States)

    Manjubala, I; Woesz, Alexander; Pilz, Christine; Rumpler, Monika; Fratzl-Zelman, Nadja; Roschger, Paul; Stampfl, Juergen; Fratzl, Peter

    2005-12-01

    Bone and cartilage generation by three-dimensional scaffolds is one of the promising techniques in tissue engineering. One approach is to generate histologically and functionally normal tissue by delivering healthy cells in biocompatible scaffolds. These scaffolds provide the necessary support for cells to proliferate and maintain their differentiated function, and their architecture defines the ultimate shape. Rapid prototyping (RP) is a technology by which a complex 3-dimensional (3D) structure can be produced indirectly from computer aided design (CAD). The present study aims at developing a 3D organic-inorganic composite scaffold with defined internal architecture by a RP method utilizing a 3D printer to produce wax molds. The composite scaffolds consisting of chitosan and hydroxyapatite were prepared using soluble wax molds. The behaviour and response of MC3T3-E1 pre-osteoblast cells on the scaffolds was studied. During a culture period of two and three weeks, cell proliferation and in-growth were observed by phase contrast light microscopy, histological staining and electron microscopy. The Giemsa and Gömöri staining of the cells cultured on scaffolds showed that the cells proliferated not only on the surface, but also filled the micro pores of the scaffolds and produced extracellular matrix within the pores. The electron micrographs showed that the cells covering the surface of the struts were flattened and grew from the periphery into the middle region of the pores.

  2. Structure of molecules and internal rotation

    CERN Document Server

    Mizushima, San-Ichiro

    1954-01-01

    Structure of Molecules and Internal Rotation reviews early studies on dihalogenoethanes. This book is organized into two parts encompassing 8 chapters that evaluate the Raman effect in ethane derivatives, the energy difference between rotational isomers, and the infrared absorption of ethane derivatives. Some of the topics covered in the book are the potential barrier to internal rotation; nature of the hindering potential; entropy difference between the rotational isomers; internal rotation in butane, pentane, and hexane; and internal rotation in long chain n-paraffins. Other chapters deal wi

  3. Literature Reviews on Modeling Internal Geometry of Textile Composites and Rate-Independent Continuum Damage

    Science.gov (United States)

    Su-Yuen, Hsu

    2011-01-01

    Textile composite materials have good potential for constructing composite structures where the effects of three-dimensional stresses are critical or geometric complexity is a manufacturing concern. There is a recent interest in advancing competence within Langley Research Center for modeling the degradation of mechanical properties of textile composites. In an initial effort, two critical areas are identified to pursue: (1) Construction of internal geometry of textile composites, and (2) Rate-independent continuum damage mechanics. This report documents reviews on the two subjects. Various reviewed approaches are categorized, their assumptions, methods, and progress are briefed, and then critiques are presented. Each review ends with recommended research.

  4. Lightning Protection for Composite Aircraft Structures

    Science.gov (United States)

    Olson, G. O.

    1985-01-01

    Lightning protection system consisting of two layers of aluminum foil separated by layer of dielectric material protects graphite/epoxy composite structures on aircraft. Protective layer is secondarily applied lightning protection system, prime advantage of which is nullification of thermal and right angle effect of lightning arc attachment to graphite/epoxy laminate.

  5. Improved Internal Reference Oxygen Sensors with Composite Ceramic Electrodes

    DEFF Research Database (Denmark)

    Hu, Qiang; Jacobsen, Torben; Hansen, Karin Vels

    2012-01-01

    Potentiometric oxygen sensors with an internal reference electrode, which uses the equilibrium pO2 of the binary mixture of Ni/NiO as the reference, are demonstrated. The cells employ Pt or composite ceramics as the sensing electrode. The cells are fabricated by a flexible and potentially low cost...... and performance are highly reproducible. The composite ceramics, based on strontium doped manganite and yttria doped zirconia, are proven superior over Pt to serve as the electrode material....

  6. Tooling Foam for Structural Composite Applications

    Science.gov (United States)

    DeLay, Tom; Smith, Brett H.; Ely, Kevin; MacArthur, Doug

    1998-01-01

    Tooling technology applications for composite structures fabrication have been expanded at MSFC's Productivity Enhancement Complex (PEC). Engineers from NASA/MSFC and Lockheed Martin Corporation have developed a tooling foam for use in composite materials processing and manufacturing that exhibits superior thermal and mechanical properties in comparison with other tooling foam materials. This tooling foam is also compatible with most preimpregnated composite resins such as epoxy, bismaleimide, phenolic and their associated cure cycles. MARCORE tooling foam has excellent processability for applications requiring either integral or removable tooling. It can also be tailored to meet the requirements for composite processing of parts with unlimited cross sectional area. A shelf life of at least six months is easily maintained when components are stored between 50F - 70F. The MARCORE tooling foam system is a two component urethane-modified polyisocyanurate, high density rigid foam with zero ozone depletion potential. This readily machineable, lightweight tooling foam is ideal for composite structures fabrication and is dimensionally stable at temperatures up to 350F and pressures of 100 psi.

  7. The International Standards Organisation offshore structures standard

    International Nuclear Information System (INIS)

    Snell, R.O.

    1994-01-01

    The International Standards Organisation has initiated a program to develop a suite of ISO Codes and Standards for the Oil Industry. The Offshore Structures Standard is one of seven topics being addressed. The scope of the standard will encompass fixed steel and concrete structures, floating structures, Arctic structures and the site specific assessment of mobile drilling and accommodation units. The standard will use as base documents the existing recommended practices and standards most frequently used for each type of structure, and will develop them to incorporate best published and recognized practice and knowledge where it provides a significant improvement on the base document. Work on the Code has commenced under the direction of an internationally constituted sub-committee comprising representatives from most of the countries with a substantial offshore oil and gas industry. This paper outlines the background to the code and the format, content and work program

  8. Analysis of Smart Composite Structures Including Debonding

    Science.gov (United States)

    Chattopadhyay, Aditi; Seeley, Charles E.

    1997-01-01

    Smart composite structures with distributed sensors and actuators have the capability to actively respond to a changing environment while offering significant weight savings and additional passive controllability through ply tailoring. Piezoelectric sensing and actuation of composite laminates is the most promising concept due to the static and dynamic control capabilities. Essential to the implementation of these smart composites are the development of accurate and efficient modeling techniques and experimental validation. This research addresses each of these important topics. A refined higher order theory is developed to model composite structures with surface bonded or embedded piezoelectric transducers. These transducers are used as both sensors and actuators for closed loop control. The theory accurately captures the transverse shear deformation through the thickness of the smart composite laminate while satisfying stress free boundary conditions on the free surfaces. The theory is extended to include the effect of debonding at the actuator-laminate interface. The developed analytical model is implemented using the finite element method utilizing an induced strain approach for computational efficiency. This allows general laminate geometries and boundary conditions to be analyzed. The state space control equations are developed to allow flexibility in the design of the control system. Circuit concepts are also discussed. Static and dynamic results of smart composite structures, obtained using the higher order theory, are correlated with available analytical data. Comparisons, including debonded laminates, are also made with a general purpose finite element code and available experimental data. Overall, very good agreement is observed. Convergence of the finite element implementation of the higher order theory is shown with exact solutions. Additional results demonstrate the utility of the developed theory to study piezoelectric actuation of composite

  9. Dynamic Failure of Composite and Sandwich Structures

    CERN Document Server

    Abrate, Serge; Rajapakse, Yapa D S

    2013-01-01

    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...

  10. Elastic constants and internal friction of fiber-reinforced composites

    International Nuclear Information System (INIS)

    Ledbetter, H.M.

    1982-01-01

    We review recent experimental studies at NBS on the anisotropic elastic constants and internal friction of fiber-reinforced composites. Materials that were studied include: boron-aluminum, boron-epoxy, graphite-epoxy, glass-epoxy, and aramid-epoxy. In all cases, elastic-constant direction dependence could be described by relationships developed for single crystals of homogeneous materials. Elastic stiffness and internal friction were found to vary inversely

  11. International Reserves and the Composition of Equity Capital Inflows

    OpenAIRE

    Xingwang Qian; Andreas Steiner

    2012-01-01

    We study the effect of central banks' international reserve hoardings on the composition of equity capital inflows, namely the ratio of portfolio equity investment (PEI) to foreign direct investment (FDI). Foreign investors' decisions regarding the location and the type of equity capital investment might be influenced by a country's level of international reserves. In a simple theoretical model, we show that higher reserves, thanks to their ability to lower exchange rate risk, reduce the risk...

  12. Particle compositions with a pre-selected cell internalization mode

    Science.gov (United States)

    Decuzzi, Paolo (Inventor); Ferrari, Mauro (Inventor)

    2012-01-01

    A method of formulating a particle composition having a pre-selected cell internalization mode involves selecting a target cell having surface receptors and obtaining particles that have i) surface moieties, that have an affinity for or are capable of binding to the surface receptors of the cell and ii) a preselected shape, where a surface distribution of the surface moieties on the particles and the shape of the particles are effective for the pre-selected cell internalization mode.

  13. 6th International Workshop on Compositional Data Analysis

    CERN Document Server

    Thió-Henestrosa, Santiago

    2016-01-01

    The authoritative contributions gathered in this volume reflect the state of the art in compositional data analysis (CoDa). The respective chapters cover all aspects of CoDa, ranging from mathematical theory, statistical methods and techniques to its broad range of applications in geochemistry, the life sciences and other disciplines. The selected and peer-reviewed papers were originally presented at the 6th International Workshop on Compositional Data Analysis, CoDaWork 2015, held in L’Escala (Girona), Spain. Compositional data is defined as vectors of positive components and constant sum, and, more generally, all those vectors representing parts of a whole which only carry relative information. Examples of compositional data can be found in many different fields such as geology, chemistry, economics, medicine, ecology and sociology. As most of the classical statistical techniques are incoherent on compositions, in the 1980s John Aitchison proposed the log-ratio approach to CoDa. This became the foundation...

  14. Studies on muon tomography for archaeological internal structures scanning

    Science.gov (United States)

    Gómez, H.; Carloganu, C.; Gibert, D.; Jacquemier, J.; Karyotakis, Y.; Marteau, J.; Niess, V.; Katsanevas, S.; Tonazzo, A.

    2016-05-01

    Muon tomography is a potential non-invasive technique for internal structure scanning. It has already interesting applications in geophysics and can be used for archaeological purposes. Muon tomography is based on the measurement of the muon flux after crossing the structure studied. Differences on the mean density of these structures imply differences on the detected muon rate for a given direction. Based on this principle, Monte Carlo simulations represent a useful tool to provide a model of the expected muon rate and angular distribution depending on the composition of the studied object, being useful to estimate the expected detected muons and to better understand the experimental results. These simulations are mainly dependent on the geometry and composition of the studied object and on the modelling of the initial muon flux at surface. In this work, the potential of muon tomography in archaeology is presented and evaluated with Monte Carlo simulations by estimating the differences on the muon rate due to the presence of internal structures and its composition. The influence of the chosen muon model at surface in terms of energy and angular distributions in the final result has been also studied.

  15. Deployable structures using bistable reeled composites

    Science.gov (United States)

    Daton-Lovett, Andrew J.; Compton-Bishop, Quentin M.; Curry, Richard G.

    2000-06-01

    This paper describes an innovative, patented use of composite materials developed by RolaTube Technology Ltd. to make smart deployable structures. Bi-stable reeled composites (BRCs) can alternate between two stable forms; that of a strong, rigid structure and that of a compact coil of flat-wound material. Bi-stability arises as a result of the manipulation of Poisson's ratio and isotropy in the various layers of the material. BRCs are made of fiber- reinforced composite materials, most often with a thermoplastic matrix. A range of fibers and polymer matrices can be used according to the requirements of the operating environment. Samples of a BRC structure were constructed using layers of unidirectional, fiber-reinforced thermoplastic sheet with the layers at different angles. The whole assembly was then consolidated under conditions of elevated temperature and pressure. The properties of the BRC are described and the result of a series of experiments performed on the sample to determine the tensile strength of the BRC structure are reported. A full analysis using finite element methods is being undertaken in collaboration with the University of Cambridge, England. The first commercial use has been to fabricate boom and drive mechanisms for the remote inspection of industrial plant.

  16. Structure and Properties of LENRA/ Silica Composite

    International Nuclear Information System (INIS)

    Mahathir Mohamed; Dahlan Mohd

    2010-01-01

    The sol-gel reaction using tetra ethoxysilane (TEOS) was conducted for modified natural rubber (NR) matrix to obtain in situ generated NR/ silica composite. The present of acrylate group in the modified NR chain turns the composite into radiation-curable. The maximum amount of silica generated in the matrix was 50 p hr by weight. During the sol-gel process the inorganic mineral was deposited in the rubber matrix forming hydrogen bonding between organic and inorganic phases. The composites obtained were characterized by various techniques including thermogravimetric analysis and infrared spectrometry to study their molecular structure. The increase in mechanical properties was observed for low silica contents ( 30 p hr) where more silica were generated, agglomerations were observed at the expense of the mechanical properties. From the DMTA data, it shows an increase of the interaction between the rubber and silica phases up to 30 p hr TEOS. Structure and morphology of the heterogeneous system were analyzed by transmission electron microscopy. The average particle sizes of between 150 nm to 300 nm were achieved for the composites that contain less than 20 p hr of TEOS. (author)

  17. Composites as structural materials in fusion reactors

    International Nuclear Information System (INIS)

    Megusar, J.

    1989-01-01

    In fusion reactors, materials are used under extreme conditions of temperature, stress, irradiation, and chemical environment. The absence of adequate materials will seriously impede the development of fusion reactors and might ultimately be one of the major difficulties. Some of the current materials problems can be solved by proper design features. For others, the solution will have to rely on materials development. A parallel and balanced effort between the research in plasma physics and fusion-related technology and in materials research is, therefore, the best strategy to ultimately achieve economic, safe, and environmentally acceptable fusion. The essential steps in developing composites for structural components of fusion reactors include optimization of mechanical properties followed by testing under fusion-reactor-relevant conditions. In optimizing the mechanical behavior of composite materials, a wealth of experience can be drawn from the research on ceramic matrix and metal matrix composite materials sponsored by the Department of Defense. The particular aspects of this research relevant to fusion materials development are methodology of the composite materials design and studies of new processing routes to develop composite materials with specific properties. Most notable examples are the synthesis of fibers, coatings, and ceramic materials in their final shapes form polymeric precursors and the infiltration of fibrous preforms by molten metals

  18. Transforming Internal Activities of Business Process Models to Services Compositions

    NARCIS (Netherlands)

    Dirgahayu, Teduh; Quartel, Dick; van Sinderen, Marten J.; Mostefaoui, S.K.; Maamar, Z.; Ferreira Pires, L.; Hammoudi, S.; Rinderle-Ma, S.; Sadiq, S.; Schulz, K.

    As a service composition language, BPEL imposes as constraint that a business process model should consist only of activities for interacting with other business processes. BPEL provides limited support for implementing internal activities, i.e. activities that are performed by a single business

  19. Thermally Conductive Structural 2D Composite Materials

    Science.gov (United States)

    2012-08-14

    Dimensional Pitch Polyimide Composite Micrographs ........ 27 Figure 23. 4-Ply Silver Polyimide Laminate ...through-thickness thermal conductivity of up to 20 W/m.K. This novel structural prepreg material will be developed through engineering of an optimal fiber...with an EPON 862/Epikure W epoxy resin system to form unidirectional prepreg tapes. Each prepreg was then cut to 6 inch by 6 inch plies and

  20. Bioinspired twisted composites based on Bouligand structures

    Science.gov (United States)

    Pinto, F.; Iervolino, O.; Scarselli, G.; Ginzburg, D.; Meo, M.

    2016-04-01

    The coupling between structural support and protection makes biological systems an important source of inspiration for the development of advanced smart composite structures. In particular, some particular material configurations can be implemented into traditional composites in order to improve their impact resistance and the out-of-plane properties, which represents one of the major weakness of commercial carbon fibres reinforced polymers (CFRP) structures. Based on this premise, a three-dimensional twisted arrangement shown in a vast multitude of biological systems (such as the armoured cuticles of Scarabei, the scales of Arapaima Gigas and the smashing club of Odontodactylus Scyllarus) has been replicated to develop an improved structural material characterised by a high level of in-plane isotropy and a higher interfacial strength generated by the smooth stiffness transition between each layer of fibrils. Indeed, due to their intrinsic layered nature, interlaminar stresses are one of the major causes of failure of traditional CFRP and are generated by the mismatch of the elastic properties between plies in a traditional laminate. Since the energy required to open a crack or a delamination between two adjacent plies is due to the difference between their orientations, the gradual angle variation obtained by mimicking the Bouligand Structures could improve energy absorption and the residual properties of carbon laminates when they are subjected to low velocity impact event. Two different bioinspired laminates were manufactured following a double helicoidal approach and a rotational one and were subjected to a complete test campaign including low velocity impact loading and compared to a traditional quasi-isotropic panel. Fractography analysis via X-Ray tomography was used to understand the mechanical behaviour of the different laminates and the residual properties were evaluated via Compression After Impact (CAI) tests. Results confirmed that the biological

  1. OOA composite structures applicable in railway industry

    Directory of Open Access Journals (Sweden)

    Rusnáková Soňa

    2017-01-01

    Full Text Available Composite sandwich structures offers several advantages over conventional structural materials such as lightweight, high bending and torsional stiffness, superior thermal insulation and excellent acoustic damping. In the aerospace industry, sandwich composites are commonly manufactured using the autoclave process which is associated with high operating cost. Out-of-autoclave (OOA manufacturing has been shown to be capable of producing low cost and high performance composites. In this paper we present results of experimental testing of various sandwich materials according various standards and actual requirements in transport industry. We compared the different types of surface and paint systems, because these layers are the most important in contact with the surrounding environment and load conditions. In the experimental measurements were used various materials. For the core of the sandwich structure were selected aluminium honeycomb, aramid honeycomb and PET (Polyethylene terephthalate foam core. Support layers were chosen two kinds of predimpregnated materials. The conditions of measurements were requirements for strength and rigidity, safety - flame resistance and reflectivity resistance. The samples were tested at the 3 - point bending test according to standard EN ISO 178, by modified test to determine the force required to rapture threaded insert, by test of reflectivity according to UIC CODE 844-4 R and according to standard EN 45545-2 fire protection of railway vehicles.

  2. Development of thermoplastic composite aircraft structures

    Science.gov (United States)

    Renieri, Michael P.; Burpo, Steven J.; Roundy, Lance M.; Todd, Stephanie A.; Kim, H. J.

    1992-01-01

    Efforts focused on the use of thermoplastic composite materials in the development of structural details associated with an advanced fighter fuselage section with applicability to transport design. In support of these designs, mechanics developments were conducted in two areas. First, a dissipative strain energy approach to material characterization and failure prediction, developed at the Naval Research Laboratory, was evaluated as a design/analysis tool. Second, a finite element formulation for thick composites was developed and incorporated into a lug analysis method which incorporates pin bending effects. Manufacturing concepts were developed for an upper fuel cell cover. A detailed trade study produced two promising concepts: fiber placement and single-step diaphragm forming. Based on the innovative design/manufacturing concepts for the fuselage section primary structure, elements were designed, fabricated, and structurally tested. These elements focused on key issues such as thick composite lugs and low cost forming of fastenerless, stiffener/moldine concepts. Manufacturing techniques included autoclave consolidation, single diaphragm consolidation (SDCC) and roll-forming.

  3. Multiphase composite coatings: structure and properties

    International Nuclear Information System (INIS)

    Yurov, V M; Guchenko, S A; Platonova, E S; Syzdykova, A Sh; Lysenko, E N

    2015-01-01

    The paper discusses the results of the research into the formation of ion-plasma multiphase coatings. The types of the formed structures are found to be not so diverse, as those formed, for example, in alloy crystallization. The structures observed are basically of globular type and, more rarely, of unclosed dissipative and cellular structures. It is shown that the properties of the coating formed in deposition are largely determined by its surface energy or surface tension. Since the magnitude of the surface tension (surface energy) in most cases is an additive quantity, each of the elements of the coating composition contributes to the total surface energy. In case of simultaneous sputtering of multiphase cathodes, high entropy coatings with an ordered cellular structure and improved mechanical properties are formed. (paper)

  4. Cooled Ceramic Matrix Composite Propulsion Structures Demonstrated

    Science.gov (United States)

    Jaskowiak, Martha H.; Dickens, Kevin W.

    2005-01-01

    NASA's Next Generation Launch Technology (NGLT) Program has successfully demonstrated cooled ceramic matrix composite (CMC) technology in a scramjet engine test. This demonstration represented the world s largest cooled nonmetallic matrix composite panel fabricated for a scramjet engine and the first cooled nonmetallic composite to be tested in a scramjet facility. Lightweight, high-temperature, actively cooled structures have been identified as a key technology for enabling reliable and low-cost space access. Tradeoff studies have shown this to be the case for a variety of launch platforms, including rockets and hypersonic cruise vehicles. Actively cooled carbon and CMC structures may meet high-performance goals at significantly lower weight, while improving safety by operating with a higher margin between the design temperature and material upper-use temperature. Studies have shown that using actively cooled CMCs can reduce the weight of the cooled flow-path component from 4.5 to 1.6 lb/sq ft and the weight of the propulsion system s cooled surface area by more than 50 percent. This weight savings enables advanced concepts, increased payload, and increased range. The ability of the cooled CMC flow-path components to operate over 1000 F hotter than the state-of-the-art metallic concept adds system design flexibility to space-access vehicle concepts. Other potential system-level benefits include smaller fuel pumps, lower part count, lower cost, and increased operating margin.

  5. Studies in stellar evolution. 3. The internal structure constants

    International Nuclear Information System (INIS)

    Hejlesen, P.M.

    1987-01-01

    This is the third paper in a series describing the results of extensive stellar evolution calculations. The internal structure constants k j (j = 2, 3, 4) have been computed for a fine grid of stellar models covering the HR-diagram from the zero-age main sequence to the subgiant region. These constants represent the influence of the internal structure on the disturbing potentials of stars, and they are needed for prediction of theoretical apsidal motion rates in close eccentric binaries as well as for other tidal effects. Results for four different initial chemical compositions are presented. The opacity tables by Cox and Stewart (1969) have been adopted, and a mixing length parameter of l/H p = 2.0 has been used throughout. The results are compared with previous calculations. A comparison with observational data for eclipsing binaries will be published elsewhere

  6. Wood-based composite materials : panel products, glued-laminated timber, structural composite lumber, and wood-nonwood composite materials

    Science.gov (United States)

    Nicole M. Stark; Zhiyong Cai; Charles Carll

    2010-01-01

    This chapter gives an overview of the general types and composition of wood-based composite products and the materials and processes used to manufacture them. It describes conventional wood-based composite panels and structural composite materials intended for general construction, interior use, or both. This chapter also describes wood–nonwood composites. Mechanical...

  7. Composite foods: from structure to sensory perception.

    Science.gov (United States)

    Scholten, Elke

    2017-02-22

    An understanding of the effect of structural features of foods in terms of specific sensory attributes is necessary to design foods with specific functionalities, such as reduced fat or increased protein content, and increased feeling of satiety or liking. Although the bulk rheological properties of both liquid and solid foods can be related to textural attributes such as thickness and firmness, they do not always correlate to more complex sensory attributes, such as creamy and smooth. These attributes are often a result of different contributions, including lubrication aspects and interactions between food and components present in the oral cavity. In this review, the different contributions for a variety of composite foods, such as dispersions, emulsions and emulsion-filled gels, are discussed. The rheological properties are discussed in relation to specific structural characteristics of the foods, which are then linked to lubrication aspects and sensory perception.

  8. Carbon composites in space vehicle structures

    Science.gov (United States)

    Mayer, N. J.

    1974-01-01

    Recent developments in the technology of carbon or graphite filaments now provide the designer with greatly improved materials offering high specific strength and modulus. Besides these advantages are properties which are distinctly useful for space applications and which provide feasibility for missions not obtainable by other means. Current applications include major and secondary structures of communications satellites. A number of R & D projects are exploring carbon-fiber application to rocket engine motor cases, advanced antenna systems, and space shuttle components. Future system studies are being made, based on the successful application of carbon fibers for orbiting space telescope assemblies, orbital transfer vehicles, and very large deployable energy generation systems. Continued technology development is needed in analysis, material standards, and advanced structural concepts to exploit the full potential of carbon filaments in composite materials.

  9. Fibre Reinforced Polymer Composites as Internal and External Reinforcements for Building Elements

    Directory of Open Access Journals (Sweden)

    Cătălin Banu

    2008-01-01

    Full Text Available During the latest decades fibre reinforced polymer (FRP composite materials have proven valuable properties and suitable to be used in construction of new buildings and in upgrading the existing ones. These materials have covered the road from research laboratory and demonstration projects to implementation in actual structures. Nowadays the civil and structural engineering communities are about to commence the stage in which the use of FRP composites is becoming a routine similar to that of traditional material such as concrete, masonry and wood. Two main issues are presented in this paper, the use of FRP composite materials for new structural members (internal reinforcements and strengthening of existing members (externally bonded reinforcements. The advantages and disadvantages as well as the problems and constraints associated with both issues are discussed in detail mainly related to concrete members.

  10. Critical joints in large composite aircraft structure

    Science.gov (United States)

    Nelson, W. D.; Bunin, B. L.; Hart-Smith, L. J.

    1983-01-01

    A program was conducted at Douglas Aircraft Company to develop the technology for critical structural joints of composite wing structure that meets design requirements for a 1990 commercial transport aircraft. The prime objective of the program was to demonstrate the ability to reliably predict the strength of large bolted composite joints. Ancillary testing of 180 specimens generated data on strength and load-deflection characteristics which provided input to the joint analysis. Load-sharing between fasteners in multirow bolted joints was computed by the nonlinear analysis program A4EJ. This program was used to predict strengths of 20 additional large subcomponents representing strips from a wing root chordwise splice. In most cases, the predictions were accurate to within a few percent of the test results. In some cases, the observed mode of failure was different than anticipated. The highlight of the subcomponent testing was the consistent ability to achieve gross-section failure strains close to 0.005. That represents a considerable improvement over the state of the art.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-01

    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

  12. Delamination Assessment Tool for Spacecraft Composite Structures

    Science.gov (United States)

    Portela, Pedro; Preller, Fabian; Wittke, Henrik; Sinnema, Gerben; Camanho, Pedro; Turon, Albert

    2012-07-01

    Fortunately only few cases are known where failure of spacecraft structures due to undetected damage has resulted in a loss of spacecraft and launcher mission. However, several problems related to damage tolerance and in particular delamination of composite materials have been encountered during structure development of various ESA projects and qualification testing. To avoid such costly failures during development, launch or service of spacecraft, launcher and reusable launch vehicles structures a comprehensive damage tolerance verification approach is needed. In 2009, the European Space Agency (ESA) initiated an activity called “Delamination Assessment Tool” which is led by the Portuguese company HPS Lda and includes academic and industrial partners. The goal of this study is the development of a comprehensive damage tolerance verification approach for launcher and reusable launch vehicles (RLV) structures, addressing analytical and numerical methodologies, material-, subcomponent- and component testing, as well as non-destructive inspection. The study includes a comprehensive review of current industrial damage tolerance practice resulting from ECSS and NASA standards, the development of new Best Practice Guidelines for analysis, test and inspection methods and the validation of these with a real industrial case study. The paper describes the main findings of this activity so far and presents a first iteration of a Damage Tolerance Verification Approach, which includes the introduction of novel analytical and numerical tools at an industrial level. This new approach is being put to the test using real industrial case studies provided by the industrial partners, MT Aerospace, RUAG Space and INVENT GmbH

  13. Chemical compositions, methods of making the chemical compositions, and structures made from the chemical compositions

    Science.gov (United States)

    Yang, Lei; Cheng, Zhe; Liu, Ze; Liu, Meilin

    2015-01-13

    Embodiments of the present disclosure include chemical compositions, structures, anodes, cathodes, electrolytes for solid oxide fuel cells, solid oxide fuel cells, fuel cells, fuel cell membranes, separation membranes, catalytic membranes, sensors, coatings for electrolytes, electrodes, membranes, and catalysts, and the like, are disclosed.

  14. 4th International Conference on Structural Nonlinear Dynamics and Diagnosis

    CERN Document Server

    2018-01-01

    This book presents contributions on the most active lines of recent advanced research in the field of nonlinear mechanics and physics selected from the 4th International Conference on Structural Nonlinear Dynamics and Diagnosis. It includes fifteen chapters by outstanding scientists, covering various aspects of applications, including road tanker dynamics and stability, simulation of abrasive wear, energy harvesting, modeling and analysis of flexoelectric nanoactuator, periodic Fermi–Pasta–Ulam problems, nonlinear stability in Hamiltonian systems, nonlinear dynamics of rotating composites, nonlinear vibrations of a shallow arch, extreme pulse dynamics in mode-locked lasers, localized structures in a photonic crystal fiber resonator, nonlinear stochastic dynamics, linearization of nonlinear resonances, treatment of a linear delay differential equation, and fractional nonlinear damping. It appeals to a wide range of experts in the field of structural nonlinear dynamics and offers researchers and engineers a...

  15. The international uranium market - structure and outlook

    International Nuclear Information System (INIS)

    Noreng, Oe.

    1978-01-01

    It is pointed out that the international uranium market is immature and is subject to factors of a political, rather than economic nature. This is due largely to potential military exploitation, which has led USA, Canada and Australia to adopt a restrictive export policy. South Africa and France, on the other hand have a more liberal attitude. The history of the market, and the development of U308 prices are then discussed and related to the phases in the commercial exploitation of nuclear power. The present market structure is described, both international and within Canada, USA, Australia, South Africa and France. The future demand is then discussed, assuming three levels of demand and various price categories. It is shown that the demand will be only slightly influenced by moderate to large increases in price, assuming price rises for coal and oil. It is concluded that the price can rise to $400-500/pound U308. (JIW)

  16. Maxwell-Higgs vortices with internal structure

    Science.gov (United States)

    Bazeia, D.; Marques, M. A.; Menezes, R.

    2018-05-01

    Vortices are considered in relativistic Maxwell-Higgs systems in interaction with a neutral scalar field. The gauge field interacts with the neutral field via the presence of generalized permeability, and the charged and neutral scalar fields interact in a way dictated by the presence of first order differential equations that solve the equations of motion. The neutral field may be seen as the source field of the vortex, and we study some possibilities, which modify the standard Maxwell-Higgs solution and include internal structure to the vortex.

  17. Direct experimental determination of the atomic structure at internal interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Browning, N.D. [Oak Ridge National Lab., TN (United States)]|[Illinois Univ., Chicago, IL (United States); Pennycook, S.J. [Oak Ridge National Lab., TN (United States)

    1995-07-01

    A crucial first step in understanding the effect that internal interfaces have on the properties of materials is the ability to determine the atomic structure at the interface. As interfaces can contain atomic disorder, dislocations, segregated impurities and interphases, sensitivity to all of these features is essential for complete experimental characterization. By combining Z-contrast imaging and electron energy loss spectroscopy (EELS) in a dedicated scanning transmission electron microscope (STEM), the ability to probe the structure, bonding and composition at interfaces with the necessary atomic resolution has been obtained. Experimental conditions can be controlled to provide, simultaneously, both incoherent imaging and spectroscopy. This enables interface structures observed in the image to be interpreted intuitively and the bonding in a specified atomic column to be probed directly by EELS. The bonding and structure information can then be correlated using bond-valence sum analysis to produce structural models. This technique is demonstrated for 25{degrees}, 36{degrees} and 67{degrees} symmetric and 45{degrees} and 25{degrees} asymmetric [001] tilt grain boundaries in SrTiO{sub 3} The structures of both types of boundary were found to contain partially occupied columns in the boundary plane. From these experimental results, a series of structural units were identified which could be combined, using continuity of gain boundary structure principles, to construct all [001] tilt boundaries in SrTiO{sub 3}. Using these models, the ability of this technique to address the issues of vacancies and dopant segregation at grain boundaries in electroceramics is discussed.

  18. The Structure and Composition of Io's Atmosphere

    Science.gov (United States)

    Smyth, W. H.; Marconi, M. L.

    2011-12-01

    Io's atmosphere is thought to be generated principally by sublimation on the dayside and by multiple volcanoes scattered throughout its surface and more concentrated near the equator. While SO2 seems to be the principle product of these sources, many other chemical species are placed into the atmosphere by these sources, including substantial amounts of SO and S2 as well as smaller but observationally significant amounts of Na bearing molecules. These species in turn interact strongly with the torus plasma generating additional species such as O2, S, O, and Na. The strong interaction of the torus plasma with the neutral atmosphere not only exerts a profound effect on the composition of Io's atmosphere but also strongly affects the dynamics and thermodynamics of Io's atmosphere, particularly at higher altitudes. In addition, as Io orbits Jupiter, the change in location of the sublimation region and the eclipse of Io as it passes through Jupiter's shadow result in substantial variation in the atmosphere. A complex time-dependent three-dimensional atmosphere with strong spatial compositional variation is created. Here we extend the two-dimensional multispecies Navier-Stokes model of Smyth and Wong (2004) to three-dimensions, include two volcanic sources similar to Pele and Loki, and include the effect of Io's movement around Jupiter on sublimation. The effects of the torus plasma are also included as in Smyth and Wong. We will present the overall composition and structure of the atmosphere, O to S ratios in the upper atmosphere, and discuss a potential issue with the O2 abundance. Smyth, W.H. and M.C. Wong, Icarus 171, 171-182, 2004.

  19. Advances in Computational Stability Analysis of Composite Aerospace Structures

    International Nuclear Information System (INIS)

    Degenhardt, R.; Araujo, F. C. de

    2010-01-01

    European aircraft industry demands for reduced development and operating costs. Structural weight reduction by exploitation of structural reserves in composite aerospace structures contributes to this aim, however, it requires accurate and experimentally validated stability analysis of real structures under realistic loading conditions. This paper presents different advances from the area of computational stability analysis of composite aerospace structures which contribute to that field. For stringer stiffened panels main results of the finished EU project COCOMAT are given. It investigated the exploitation of reserves in primary fibre composite fuselage structures through an accurate and reliable simulation of postbuckling and collapse. For unstiffened cylindrical composite shells a proposal for a new design method is presented.

  20. Structural design of a composite bicycle fork

    International Nuclear Information System (INIS)

    Baldissera, Paolo; Delprete, Cristiana

    2014-01-01

    Highlights: • Case study about composite bicycle fork design. • Special requirements for a Student Team project. • FE model to evaluate stiffness, strength and potential failure modes. • Comparison of two manufacturing approaches. • FE model stiffness validation on the manufactured fork. - Abstract: Despite the wide literature on the mechanical behaviour of carbon/epoxy composites, it is rare to find practical methodological approaches in finite element design of structural components made by laminate layup. Through the case study of a special bicycle fork needed in a Student Team prototype, this paper proposes a simplified methodology as starting point for educational and manufacturing purposes. In order to compare two manufacturing solutions in terms of stiffness, strength and failure mode, a numerical model was implemented. Since the project requirements imposed to avoid standard destructive testing, the model validation was based on a posteriori linear stiffness comparison with the manufactured component. The slight discrepancies between experimental and numerical results were discussed in order to check their origin and to assess the reliability of the model. The overall methodology, even if complain with only a part of the safety standard requirements, shows to be reliable enough and can be the basis for further extension and refinement

  1. Improved Internal Reference Oxygen Sensors Using Composite Oxides as Electrodes

    DEFF Research Database (Denmark)

    Hu, Qiang

    The thesis describes the research on and development of an internal reference oxygen sensor (IROS). The IROS is potentiometric and uses the equilibrium pO2of the binary mixture of Ni/NiO as the reference pO2. The sensing electrode of the IROS are made from metallic Pt or the composite of (La0.75S...... the application of IROSes are provided. Based on the concepts and fundamentals of the IROS, internal reference sensors that detect other gas species such as hydrogen, chlorine and bromine may be developed.......The thesis describes the research on and development of an internal reference oxygen sensor (IROS). The IROS is potentiometric and uses the equilibrium pO2of the binary mixture of Ni/NiO as the reference pO2. The sensing electrode of the IROS are made from metallic Pt or the composite of (La0.75Sr0...... from 8YSZ is evaluated quantitatively and figures that may be used to design the depletion period of an IROS due to the electronic leak of 8YSZ are provided. One dimensional numerical simulations are performed to study the variation in cell voltage during the process of gas mixing, and the asymmetric...

  2. Braided reinforced composite rods for the internal reinforcement of concrete

    Science.gov (United States)

    Gonilho Pereira, C.; Fangueiro, R.; Jalali, S.; Araujo, M.; Marques, P.

    2008-05-01

    This paper reports on the development of braided reinforced composite rods as a substitute for the steel reinforcement in concrete. The research work aims at understanding the mechanical behaviour of core-reinforced braided fabrics and braided reinforced composite rods, namely concerning the influence of the braiding angle, the type of core reinforcement fibre, and preloading and postloading conditions. The core-reinforced braided fabrics were made from polyester fibres for producing braided structures, and E-glass, carbon, HT polyethylene, and sisal fibres were used for the core reinforcement. The braided reinforced composite rods were obtained by impregnating the core-reinforced braided fabric with a vinyl ester resin. The preloading of the core-reinforced braided fabrics and the postloading of the braided reinforced composite rods were performed in three and two stages, respectively. The results of tensile tests carried out on different samples of core-reinforced braided fabrics are presented and discussed. The tensile and bending properties of the braided reinforced composite rods have been evaluated, and the results obtained are presented, discussed, and compared with those of conventional materials, such as steel.

  3. Internal friction in a new kind of metal matrix composites

    International Nuclear Information System (INIS)

    San Juan, J.; No, M.L.

    2006-01-01

    We have developed a new kind of metal matrix composites, based on powders of Cu-Al-Ni shape memory alloys (SMAs) surrounded by an indium matrix, specifically designed to exhibit high mechanical damping. The damping properties have been characterized by mechanical spectroscopy as a function of temperature between 150 and 400 K, frequency between 3 x 10 -3 and 3 Hz, and strain amplitude between 5 x 10 -6 and 10 -4 . The material exhibits, in some range of temperature, internal friction as high as 0.54. The extremely high damping is discussed in the light of the microstructure of the material, which has been characterized in parallel

  4. Combined use of polymer composites and metals in engineering structures

    International Nuclear Information System (INIS)

    Hoa, S.V.

    2002-01-01

    Polymer matrix composites have found many applications in the construction of light weight structures such as those in aircrafts, automobiles, sports equipment etc. This is because these materials possess high stiffness, high strength and low densities. In applications of polymer matrix composites in the light weight structures, the polymer composites are however, not used by themselves alone in most cases. Usually the polymer composites are used in conjunction with some metal components. The metal components are used either to provide means for joining the composite components or the composites are used to repair the cracked metal structures. The synergistic effect of both metals and composites can provide excellent performance with good economy. This paper presents a few applications where polymer composites are used in conjunction with metals in engineering structures. (author)

  5. An Improved Design Methodology for Modeling Thick-Section Composite Structures Using a Multiscale Approach

    Science.gov (United States)

    2012-09-01

    case study no. 2. The multiaxial loading combined with XZ and YZ Poisson ratio effects contributes to strains in the Z-direction of the sample. The...E. A Continuum Damage Model for Fiber Reinforced Laminates Based on Ply Failure Mechanisms, Composite Structures. Fifteenth International...output parameters, stiffness ratios , to analyze the nonlinear response and progressive failure of the composite structure is developed. These new

  6. A reexamination and extension of international strategy-structure theory

    OpenAIRE

    Wolf, Joachim; Egelhoff, William G.

    2001-01-01

    Using a sample of 95 German firms, the study finds general support for the traditional fits of international strategy-structure theory. Employing an information-processing perspective, the study conceptually and empirically extends existing theory (1) to address strategy-structure fit for various types of matrix structure, and (2) by adding two new elements of international strategy to the existing international strategy-structure model: the level of international transfers and level of forei...

  7. RILEM International Symposium on Materials and Joints in Timber Structures

    CERN Document Server

    Reinhardt, H-W; Garrecht, Harald

    2014-01-01

    This book contains the contributions from the RILEM International Symposium on Materials and Joints in Timber Structures that was held in Stuttgart, Germany from October 8 to 10, 2013. It covers recent developments in the materials and the joints used in modern timber structures. Regarding basic wooden materials, the contributions highlight the widened spectrum of products comprising cross-laminated timber, glulam and LVL from hardwoods and block glued elements. Timber concrete compounds, cement bonded wood composites and innovative light-weight constructions represent increasingly employed alternatives for floors, bridges and facades. With regard to jointing technologies, considerable advances in both mechanical connections and glued joints are presented. Self-tapping screws have created unprecedented options for reliable, strong as well as ductile joints and reinforcement technologies. Regarding adhesives, which constitute the basis of the jointing/laminating technology of modern timber products, extended o...

  8. Braided Composite Technologies for Rotorcraft Structures

    Science.gov (United States)

    Jessie, Nathan

    2015-01-01

    A&P Technology has developed a braided material approach for fabricating lightweight, high-strength hybrid gears for aerospace drive systems. The conventional metallic web was replaced with a composite element made from A&P's quasi-isotropic braid. The 0deg, +/-60deg braid architecture was chosen so that inplane stiffness properties and strength would be nearly equal in all directions. The test results from the Phase I Small Spur Gear program demonstrated satisfactory endurance and strength while providing a 20 percent weight savings. (Greater weight savings is anticipated with structural optimization.) The hybrid gears were subjected to a proof-of-concept test of 1 billion cycles in a gearbox at 10,000 revolutions per minute and 490 in-lb torque with no detectable damage to the gears. After this test the maximum torque capability was also tested, and the static strength capability of the gears was 7x the maximum operating condition. Additional proof-of-concept tests are in progress using a higher oil temperature, and a loss-of-oil test is planned. The success of Phase I led to a Phase II program to develop, fabricate, and optimize full-scale gears, specifically Bull Gears. The design of these Bull Gears will be refined using topology optimization, and the full-scale Bull Gears will be tested in a full-scale gear rig. The testing will quantify benefits of weight savings, as well as noise and vibration reduction. The expectation is that vibration and noise will be reduced through the introduction of composite material in the vibration transmission path between the contacting gear teeth and the shaft-and-bearing system.

  9. Self-force as probe of internal structure

    International Nuclear Information System (INIS)

    Isoyama, Soichiro; Poisson, Eric

    2012-01-01

    The self-force acting on a (scalar or electric) charge held in place outside a massive body contains information about the body's composition, and can therefore be used as a probe of internal structure. We explore this theme by computing the (scalar or electromagnetic) self-force when the body is a spherical ball of perfect fluid in hydrostatic equilibrium, under the assumption that its rest-mass density and pressure are related by a polytropic equation of state. The body is strongly self-gravitating, and all computations are performed in exact general relativity. The dependence on internal structure is best revealed by expanding the self-force in powers of r -1 0 , with r 0 denoting the radial position of the charge outside the body. To the leading order, the self-force scales as r -3 0 and depends only on the square of the charge and the body's mass; the leading self-force is universal. The dependence on internal structure is seen at the next order, r -5 0 , through a structure factor that depends on the equation of state. We compute this structure factor for relativistic polytropes, and show that for a fixed mass, it increases linearly with the body's radius in the case of the scalar self-force, and quadratically with the body's radius in the case of the electromagnetic self-force. In both cases we find that for a fixed mass and radius, the self-force is smaller if the body is more centrally dense, and larger if the mass density is more uniformly distributed. (paper)

  10. Internal energy relaxation in shock wave structure

    International Nuclear Information System (INIS)

    Josyula, Eswar; Suchyta, Casimir J.; Boyd, Iain D.; Vedula, Prakash

    2013-01-01

    The Wang Chang-Uhlenbeck (WCU) equation is numerically integrated to characterize the internal structure of Mach 3 and Mach 5 shock waves in a gas with excitation in the internal energy states for the treatment of inelastic collisions. Elastic collisions are modeled with the hard sphere collision model and the transition rates for the inelastic collisions modified appropriately using probabilities based on relative velocities of the colliding particles. The collision integral is evaluated by the conservative discrete ordinate method [F. Tcheremissine, “Solution of the Boltzmann kinetic equation for high-speed flows,” Comput. Math. Math. Phys. 46, 315–329 (2006); F. Cheremisin, “Solution of the Wang Chang-Uhlenbeck equation,” Dokl. Phys. 47, 487–490 (2002)] developed for the Boltzmann equation. For the treatment of the diatomic molecules, the internal energy modes in the Boltzmann equation are described quantum mechanically given by the WCU equation. As a first step in the treatment of the inelastic collisions by the WCU equation, a two- and three-quantum system is considered to study the effect of the varying of (1) the inelastic cross section and (2) the energy gap between the quantum energy states. An alternative method, the direct simulation Monte Carlo method, is used for the Mach 3 shock wave to ensure the consistency of implementation in the two methods and there is an excellent agreement between the two methods. The results from the WCU implementation showed consistent trends for the Mach 3 and Mach5 standing shock waves simulations. Inelastic contributions change the downstream equilibrium state and allow the flow to transition to the equilibrium state further upstream

  11. CHANGES IN STRUCTURE OF ROMANIA'S INTERNATIONAL TRADE

    Directory of Open Access Journals (Sweden)

    CECILIA IRINA RABONTU

    2014-05-01

    Full Text Available Evolution of structural changes in Romanian trade is somewhat interesting if you look at it from the perspective of mutations that occurred in the categories of goods and services subject to international trade. After the Revolution of 1989, the Romanian economy has gone through dramatic changes that had determinate a total reconfiguration of foreign trade. At the same time, the economic instability has had further repercussions on the Romanian economy manifested through higher prices, reduced wages or earnings, reduced employment and rising unemployment, increasing interest rates on loans due to the devaluation of the national currency, increase value-added tax, consumption reduction etc. We proposed in this paper an analyze for a significant period of time evolution of international trade in goods and services of Romania in order to establish the main categories of goods traded but Romania's main trading partners, too. In order to achieve the central goal of this paper we will use statistical data found in the databases provided by the WTO, Eurostat and the National Statistical Institutes and statistical methods to support our initiative.

  12. 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)

    2015-05-01

    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.

  13. Internal wave structures in abyssal cataract flows

    Science.gov (United States)

    Makarenko, Nikolay; Liapidevskii, Valery; Morozov, Eugene; Tarakanov, Roman

    2014-05-01

    We discuss some theoretical approaches, experimental results and field data concerning wave phenomena in ocean near-bottom stratified flows. Such strong flows of cold water form everywhere in the Atlantic abyssal channels, and these currents play significant role in the global water exchange. Most interesting wave structures arise in a powerful cataract flows near orographic obstacles which disturb gravity currents by forced lee waves, attached hydraulic jumps, mixing layers etc. All these effects were observed by the authors in the Romanche and Chain fracture zones of Atlantic Ocean during recent cruises of the R/V Akademik Ioffe and R/V Akademik Sergei Vavilov (Morozov et al., Dokl. Earth Sci., 2012, 446(2)). In a general way, deep-water cataract flows down the slope are similar to the stratified flows examined in laboratory experiments. Strong mixing in the sill region leads to the splitting of the gravity current into the layers having the fluids with different densities. Another peculiarity is the presence of critical layers in shear flows sustained over the sill. In the case under consideration, this critical level separates the flow of near-bottom cold water from opposite overflow. In accordance with known theoretical models and laboratory measurements, the critical layer can absorb and reflect internal waves generated by the topography, so the upward propagation of these perturbations is blocked from above. High velocity gradients were registered downstream in the vicinity of cataract and it indicates the existence of developed wave structures beyond the sill formed by intense internal waves. This work was supported by RFBR (grants No 12-01-00671-a, 12-08-10001-k and 13-08-10001-k).

  14. Modeling Bistable Composite Laminates for Piezoelectric Morphing Structures

    OpenAIRE

    Darryl V. Murray; Oliver J. Myers

    2013-01-01

    A sequential modeling effort for bistable composite laminates for piezoelectric morphing structures is presented. Thin unsymmetric carbon fiber composite laminates are examined for use of morphing structures using piezoelectric actuation. When cooling from the elevated cure temperature to room temperature, these unsymmetric composite laminates will deform. These postcure room temperature deformation shapes can be used as morphing structures. Applying a force to these deformed laminates will c...

  15. Composite corrugated structures for morphing wing skin applications

    International Nuclear Information System (INIS)

    Thill, C; Etches, J A; Bond, I P; Potter, K D; Weaver, P M

    2010-01-01

    Composite corrugated structures are known for their anisotropic properties. They exhibit relatively high stiffness parallel (longitudinal) to the corrugation direction and are relatively compliant in the direction perpendicular (transverse) to the corrugation. Thus, they offer a potential solution for morphing skin panels (MSPs) in the trailing edge region of a wing as a morphing control surface. In this paper, an overview of the work carried out by the present authors over the last few years on corrugated structures for morphing skin applications is first given. The second part of the paper presents recent work on the application of corrugated sandwich structures. Panels made from multiple unit cells of corrugated sandwich structures are used as MSPs in the trailing edge region of a scaled morphing aerofoil section. The aerofoil section features an internal actuation mechanism that allows chordwise length and camber change of the trailing edge region (aft 35% chord). Wind tunnel testing was carried out to demonstrate the MSP concept but also to explore its limitations. Suggestions for improvements arising from this study were deduced, one of which includes an investigation of a segmented skin. The overall results of this study show that the MSP concept exploiting corrugated sandwich structures offers a potential solution for local morphing wing skins for low speed and small air vehicles

  16. Internal structure of reactor building for Madras Atomic Power Project

    International Nuclear Information System (INIS)

    Pandit, D.P.

    1975-01-01

    The structural configuration and analysis of structural elements of the internal structure of reactor building for the Madras Atomic Power Project has been presented. Two methods of analysis of the internal structure, viz. Equivalent Plane Frame and Finite Element Method, are explained and compared with the use of bending moments obtained. (author)

  17. Composites structures for bone tissue reconstruction

    International Nuclear Information System (INIS)

    Neto, W.; Santos, João; Avérous, L.; Schlatter, G.; Bretas, Rosario

    2015-01-01

    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

  18. Composites structures for bone tissue reconstruction

    Science.gov (United States)

    Neto, W.; Santos, João.; Avérous, L.; Schlatter, G.; Bretas, Rosario.

    2015-05-01

    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.

  19. 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.

    2013-01-01

    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

  20. 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.

    2013-01-01

    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

  1. Hybrid Composite Structures : Multifunctionality through Metal Fibres

    NARCIS (Netherlands)

    Ahmed, T.

    2009-01-01

    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

  2. Floristic Composition and Structure of Yegof Mountain Forest, South ...

    African Journals Online (AJOL)

    Floristic Composition and Structure of Yegof Mountain Forest, South Wollo, Ethiopia. S Mohammed, B Abraha. Abstract. In this study, Floristic composition, diversity, population structure and regeneration status of woody plant species of Yegof Forest in South Wollo Zone, Amhara Regional State, Ethiopia were analyzed.

  3. The crack energy absorptive capacity of composites with fractal structure

    International Nuclear Information System (INIS)

    Lung, C.W.

    1990-11-01

    This paper discusses the energy absorptive capacity of composites with fibers of fractal structures. It is found that this kind of structure may increase the absorption energy during the crack propagation and hence the fracture toughness of composites. (author). 10 refs, 6 figs, 2 tabs

  4. Progressive fracture of polymer matrix composite structures: A new approach

    Science.gov (United States)

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

    1992-01-01

    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. Structural and failure mechanics of sandwich composites

    CERN Document Server

    Carlsson, LA; Carlsson, Leif A

    2011-01-01

    Focusing on important deformation and failure modes of sandwich structures, this volume describes the mechanics behind fracture processes. The text also reviews test methods developed for the cr, structural integrity, and failure mechanisms of sandwich structures.

  6. Nonlinear Analysis and Scaling Laws for Noncircular Composite Structures Subjected to Combined Loads

    Science.gov (United States)

    Hilburger, Mark W.; Rose, Cheryl A.; Starnes, James H., Jr.

    2001-01-01

    Results from an analytical study of the response of a built-up, multi-cell noncircular composite structure subjected to combined internal pressure and mechanical loads are presented. Nondimensional parameters and scaling laws based on a first-order shear-deformation plate theory are derived for this noncircular composite structure. The scaling laws are used to design sub-scale structural models for predicting the structural response of a full-scale structure representative of a portion of a blended-wing-body transport aircraft. Because of the complexity of the full-scale structure, some of the similitude conditions are relaxed for the sub-scale structural models. Results from a systematic parametric study are used to determine the effects of relaxing selected similitude conditions on the sensitivity of the effectiveness of using the sub-scale structural model response characteristics for predicting the full-scale structure response characteristics.

  7. Lightweight, Composite Cryogenic Tank Structures, Phase I

    Data.gov (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...

  8. Flame-Resistant Composite Materials For Structural Members

    Science.gov (United States)

    Spears, Richard K.

    1995-01-01

    Matrix-fiber composite materials developed for structural members occasionally exposed to hot, corrosive gases. Integral ceramic fabric surface layer essential for resistance to flames and chemicals. Endures high temperature, impedes flame from penetrating to interior, inhibits diffusion of oxygen to interior where it degrades matrix resin, resists attack by chemicals, helps resist erosion, and provides additional strength. In original intended application, composite members replace steel structural members of rocket-launching structures that deteriorate under combined influences of atmosphere, spilled propellants, and rocket exhaust. Composites also attractive for other applications in which corrosion- and fire-resistant structural members needed.

  9. Numerical Study of the Thermal Behaviour of a Thermo-Structural Aeronautical Composite under Fire Stress

    OpenAIRE

    Grange , N; Chetehouna , K; Gascoin , Nicolas; Senave , S

    2015-01-01

    International audience; The use of composite materials for aeronautical applications has been growing since several years because of the opportunity to produce lightweight structures reducing the fuel bills and emissions. The need for fireproof certification imposes costly and time consuming experiments that might be replaced or complemented in the years to come by numerical calculations. The present work creates a CFD numerical model of a fireproof test. As an example, a composite part (plen...

  10. Durability of commercial aircraft and helicopter composite structures

    International Nuclear Information System (INIS)

    Dexter, H.B.

    1982-01-01

    The development of advanced composite technology during the past decade is discussed. Both secondary and primary components fabricated with boron, graphite, and Kevlar composites are evaluated. Included are spoilers, rudders, and fairings on commercial transports, boron/epoxy reinforced wing structure on C-130 military transports, and doors, fairings, tail rotors, vertical fins, and horizontal stabilizers on commercial helicopters. The development of composite structures resulted in advances in design and manufacturing technology for secondary and primary composite structures for commercial transports. Design concepts and inspection and maintenance results for the components in service are reported. The flight, outdoor ground, and controlled laboratory environmental effects on composites were also determined. Effects of moisture absorption, ultraviolet radiation, aircraft fuels and fluids, and sustained tensile stress are included. Critical parameters affecting the long term durability of composite materials are identified

  11. Durability of commercial aircraft and helicopter composite structures

    Science.gov (United States)

    Dexter, H. B.

    1982-01-01

    The development of advanced composite technology during the past decade is discussed. Both secondary and primary components fabricated with boron, graphite, and Kevlar composites are evaluated. Included are spoilers, rudders, and fairings on commercial transports, boron/epoxy reinforced wing structure on C-130 military transports, and doors, fairings, tail rotors, vertical fins, and horizontal stabilizers on commercial helicopters. The development of composite structures resulted in advances in design and manufacturing technology for secondary and primary composite structures for commercial transports. Design concepts and inspection and maintenance results for the components in service are reported. The flight, outdoor ground, and controlled laboratory environmental effects on composites were also determined. Effects of moisture absorption, ultraviolet radiation, aircraft fuels and fluids, and sustained tensile stress are included. Critical parameters affecting the long term durability of composite materials are identified.

  12. Ultimate internal pressure capacity assessment of SC structure

    International Nuclear Information System (INIS)

    Park, Hyungkui; Choi, Inkil

    2013-01-01

    An SC structure applied to a containment building can be quite effective. However, an SC structure cannot be applied to a containment building, because its internal pressure resistance performance has not been verified. The containment building, which undergoes ultimate internal pressure, resists the internal pressure through a pre-stress tendon. It is hard to apply a tendon to an SC structure because of its structural characteristics. Therefore, the internal pressure resistance performance of the SC structure itself should be ensured to apply it to a structure with internal pressure resistance. In this study, the suitability of an SC structure as a substitution for the tendon of a pressure resistant structure was evaluated. A containment structure model was used in this study, because it was representative structures that resistance of ultimate internal pressure be required. In this study, a nonlinear analysis was performed to evaluate and compare the behaviors of tendon model and SC structure model. By comparing the internal pressure-displacement according to the structure type, the stability of SC structure model was assessed

  13. The Effects of Changing Membrane Compositions and Internal Electrolytes on the Respon of Potassium Ion Sensor

    OpenAIRE

    Ulianas, Alizar; Heng, Lee Yook

    2015-01-01

    A study on the changing of membrane compositions and internal solution towards the response potassium ion sensor was carried out. Potassium ion sensor based on photocured cross linking poly(n-butyl acrylate) membranes with varying composition of valinomycin (val), sodium tetrakis [3.5-bis(trifluoro-methyl) phenyl] borat (NaTFPB), types ion of internal solution were investigated. Effects of varying composition of val, NaTFPB, types and concentration of internal solution were observed on potass...

  14. 3D flexible NiTi-braided elastomer composites for smart structure applications

    International Nuclear Information System (INIS)

    Heller, L; Vokoun, D; Šittner, P; Finckh, H

    2012-01-01

    While outstanding functional properties of thin NiTi wires are nowadays well recognized and beneficially utilized in medical NiTi devices, development of 2D/3D wire structures made out of these NiTi wires remains challenging and mostly unexplored. The research is driven by the idea of creating novel 2D/3D smart structures which inherit the functional properties of NiTi wires and actively utilize geometrical deformations within the structure to create new/improved functional properties. Generally, textile technology provides attractive processing methods for manufacturing 2D/3D smart structures made out of NiTi wires. Such structures may be beneficially combined with soft elastomers to create smart deformable composites. Following this route, we carried out experimental work focused on development of 3D flexible NiTi-braided elastomer composites involving their design, laboratory manufacture and thermomechanical testing. We describe the manufacturing technology and structural properties of these composites; and perform thermomechanical tests on the composites, focusing particularly on quasistatic tensile properties, energy absorption, damping and actuation under tensile loading. Functional thermomechanical properties of the composites are discussed with regard to the mechanical properties of the components and architecture of the composites. It is found that the composites indeed inherit all important features of the thermomechanical behavior of NiTi wires but, due to their internal architecture, outperform single NiTi wires in some features such as the magnitude of recoverable strain, superelastic damping capacity and thermally induced actuation strain. (paper)

  15. Developing organizational structures for international marketing

    OpenAIRE

    Ioan Cucu

    2002-01-01

    International marketing represents marketing activities performed across national boundaries. The level of involvement in international marketing can range from casual exporting to globalization of markets. Although most firms adjust their marketing mixes for differences in target markets, some firms are able to standardize their marketing efforts worldwide

  16. Multifunctional Composite Nanofibers for Smart Structures

    Science.gov (United States)

    2011-10-13

    such as the Shape Memory Alloy (SMA) and/or shape memory polymer (SMP) and other hybrid systems. We specifically attempt to answer the following...stress induced from SiNP expansion upon alloying with Li ions. The cycling performance of core-shell CNF/SiNP composite is compared with that of non...Ayranci, Frank Ko, Tucker Howie, MinoruTaya, “Shape memory effect of a thermoset polymer and its fiber reinforced composites, submitted to the 18th

  17. Diamond structures grown from polymer composite nanofibers

    Czech Academy of Sciences Publication Activity Database

    Potocký, Štěpán; Kromka, Alexander; Babchenko, Oleg; Rezek, Bohuslav; Martinová, L.; Pokorný, P.

    2013-01-01

    Roč. 5, č. 6 (2013), s. 519-521 ISSN 2164-6627 R&D Projects: GA ČR GAP108/12/0910; GA ČR GAP205/12/0908 Institutional support: RVO:68378271 Keywords : chemical vapour deposition * composite polymer * nanocrystalline diamond * nanofiber sheet * SEM Subject RIV: BM - Solid Matter Physics ; Magnetism

  18. A Review of Structural Performance of Oil Palm Empty Fruit Bunch Fiber in Polymer Composites

    Directory of Open Access Journals (Sweden)

    Reza Mahjoub

    2013-01-01

    Full Text Available According to environmental concerns and financial problems, natural fibers have become interesting and fascinating nowadays to be used as an industrial material and structural material for rehabilitating of structures. Oil palm empty fruit bunch fiber (OPF is a natural fiber which is found a lot in tropical areas. Scientists have used OPF fiber with many types of resins such as epoxy, polypropylene, polyester, and phenol formaldehyde. Therefore, this paper focused on the properties of OPF fiber and gathered mechanical properties of OPF composites (OPF as reinforcement of polymer reported by other researchers in terms of tensile and flexural properties. Furthermore, the chemical surface modification methods to solve the interfacial bonding of fiber and polymer were mentioned. In addition, the results of hybrid composites of OPF were also discussed in this paper. Meanwhile, the results of composites were compared to pure resin properties and also the stress-strain diagram and internal strain energy of composites were considered. Besides, the effects of adding OPF to other composites to make a new hybrid composite were indicated. Finally, it is clear that the use of oil palm fiber composites for structural elements for bearing loads is not recommended but the usage of OPF composites for secondary structural elements may be recommended due to future researches.

  19. Composite materials application on FORMOSAT-5 remote sensing instrument structure

    Directory of Open Access Journals (Sweden)

    Jen-Chueh Kuo

    2017-01-01

    Full Text Available Composite material has been widely applied in space vehicle structures due to its light weight and designed stiffness modulus. Some special mechanical properties that cannot be changed in general metal materials, such as low CTE (coefficient of thermal expansion and directional material stiffness can be artificially adjusted in composite materials to meet the user’s requirements. Space-qualified Carbon Fiber Reinforced Plastic (CFRP composite materials are applied In the FORMOSAT-5 Remote Sensing (RSI structure because of its light weight and low CTE characteristics. The RSI structural elements include the primary mirror supporting plate, secondary mirror supporting ring, and supporting frame. These elements are designed, manufactured, and verified using composite materials to meet specifications. The structure manufacturing process, detailed material properties, and CFRP structural element validation methods are introduced in this paper.

  20. Simulating the structure of gypsum composites using pulverized basalt waste

    Directory of Open Access Journals (Sweden)

    Buryanov Аleksandr

    2017-01-01

    Full Text Available This paper examines the possibility of simulating the structure of gypsum composite modified with basalt dust waste to make materials and products based on it. Structural simulating of the topological space in gypsum modified composite by optimizing its grain-size composition highly improves its physical and mechanical properties. Strength and density tests have confirmed the results of the simulation. The properties of modified gypsum materials are improved by obtaining of denser particle packing in the presence of hemihydrate of finely dispersed basalt and plasticizer particles in the system, and by engaging basalt waste in the structuring process of modified gypsum stone.

  1. Advanced organic composite materials for aircraft structures: Future program

    Science.gov (United States)

    1987-01-01

    Revolutionary advances in structural materials have been responsible for revolutionary changes in all fields of engineering. These advances have had and are still having a significant impact on aircraft design and performance. Composites are engineered materials. Their properties are tailored through the use of a mix or blend of different constituents to maximize selected properties of strength and/or stiffness at reduced weights. More than 20 years have passed since the potentials of filamentary composite materials were identified. During the 1970s much lower cost carbon filaments became a reality and gradually designers turned from boron to carbon composites. Despite progress in this field, filamentary composites still have significant unfulfilled potential for increasing aircraft productivity; the rendering of advanced organic composite materials into production aircraft structures was disappointingly slow. Why this is and research and technology development actions that will assist in accelerating the application of advanced organic composites to production aircraft is discussed.

  2. The International Registry on Hand and Composite Tissue Transplantation.

    Science.gov (United States)

    Petruzzo, Palmina; Lanzetta, Marco; Dubernard, Jean-Michel; Landin, Luis; Cavadas, Pedro; Margreiter, Raimund; Schneeberger, Stephan; Breidenbach, Warren; Kaufman, Christina; Jablecki, Jerzy; Schuind, Frédéric; Dumontier, Christian

    2010-12-27

    The International Registry on Hand and Composite Tissue Transplantation was founded in May 2002, and the analysis of all cases with follow-up information up to July 2010 is presented here. From September 1998 to July 2010, 49 hands (17 unilateral and 16 bilateral hand transplantations, including 1 case of bilateral arm transplantation) have been reported, for a total of 33 patients. They were 31 men and 2 women (median age 32 years). Time since hand loss ranged from 2 months to 34 years, and in 46% of cases, the level of amputation was at wrist. Immunosuppressive therapy included tacrolimus, mycophenolate mofetil, sirolimus, and steroids; polyclonal or monoclonal antibodies were used for induction. Topical immunosuppression was also used in several cases. Follow-up ranges from 1 month to 11 years. One patient died on day 65. Three patients transplanted in the Western countries have lost their graft, whereas until September 2009, seven hand grafts were removed for noncompliance to the immunosuppressive therapy in China. Eighty-five percent of recipients experienced at least one episode of acute rejection within the first year, and they were reversible when promptly treated. Side effects included opportunistic infections, metabolic complications, and malignancies. All patients developed protective sensibility, 90% of them developed tactile sensibility, and 82.3% also developed a discriminative sensibility. Motor recovery enabled patients to perform most daily activities. Hand transplantation is a complex procedure, and its success is based on patient's compliance and his or her careful evaluation before and after transplantation.

  3. Nano-structured polymer composites and process for preparing same

    Science.gov (United States)

    Hillmyer, Marc; Chen, Liang

    2013-04-16

    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.

  4. Kinetics of radiation-induced structural alterations in electron-irradiated polymer-based composites

    International Nuclear Information System (INIS)

    Zaikin, Yu.A.; Potanin, A.S.; Koztaeva, U.P.

    2002-01-01

    Complete text of publication follows. In our previous studies measurements of internal friction temperature dependence were used for characterization of thermally activated and radiation-induced structural evolution in different types of polymer-based composites. This paper supplements these measurements with kinetic studies of internal friction (IF) parameters and EPR signals in a glass-cloth epoxy-filled laminate ST-ETF after electron irradiation up to doses of 1-10 MGy. Experiment have shown that the lifetime of free radicals in this composite considerably exceeds the characteristic time of molecular structural rearrangement due to scission and cross-linking after irradiation, as determined from IF measurements. This result is explained by slow proceeding of sterically hindered disproportionation reactions that stabilize the end groups of the macro-chain disrupt during irradiation and finally fix the act of scission. A mathematical model is formulated for description of structural evolution and alterations of IF parameters in polymer-based composites during and after electron irradiation. The description is based on the track model of radiation damage in polymers and phenomenological theory of radiation-induced structural transformations. General description does not give details of radiation-chemical conversion in different structural components of composites but indicates the direction of their structural evolution. In the model considered a composite material was divided into three parts (binder, filler, and a boundary layer). It was supposed that after primary distribution of radiation energy radiation-chemical conversion proceeds independently in each of these regions. It was also suggested that all the radical reactions were of the second order. On the example of glass-cloth laminate ST-ETF it is shown that this model allows to describe alterations in composite structural characteristics during irradiation and in the course of their self-organization after

  5. Analyzing the Structure of the International Business Curriculum in India

    Science.gov (United States)

    Srivastava, Deepak K.

    2012-01-01

    This article analyzes the structure of the international business curriculum through a questionnaire-based survey among current students and young managers who are studying or have studied international business courses in one of the top B-Schools of India. Respondents have the opinion that international business is more than internationalization…

  6. Casein micelles and their internal structure

    NARCIS (Netherlands)

    de Kruif, C.G.; Huppertz, T.; Urban, V.S.; Petukhov, A.V.

    2012-01-01

    The internalstructure of caseinmicelles was studied by calculating the small-angle neutron and X-ray scattering and static light scattering spectrum (SANS, SAXS, SLS) as a function of the scattering contrast and composition. We predicted experimental SANS, SAXS, SLS spectra self consistently using

  7. Stiff, Strong Splice For A Composite Sandwich Structure

    Science.gov (United States)

    Schmaling, D.

    1991-01-01

    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.

  8. Structured Piezoelectric Composites: Materials and Applications

    OpenAIRE

    Van den Ende, D.A.

    2012-01-01

    The piezoelectric effect, which causes a material to generate a voltage when it deforms, is very suitable for making integrated sensors, and (micro-) generators. However, conventional piezoelectric materials are either brittle ceramics or certain polymers with a low thermal stability, which limits their practical application to certain specific fields. Piezoelectric composites, which contain an active piezoelectric (ceramic) phase in a robust polymer matrix, can potentially have better proper...

  9. Flexible Nanocellulose - Nanoparticle Composites: Structures and Properties

    OpenAIRE

    UTHPALA MANAVI GARUSINGHE

    2018-01-01

    Nanocellulose is biodegradable and renewable and has many attractive properties of technological interest. Therefore, nanocellulose can be converted into thin films, which is used in wide range of applications. However, the property range achievable with nanocellulose by itself still has limitations. This thesis focuses on the production of nanocellulose-inorganic nanoparticle composites to combine the advantage associated with both individual components together to extend the range of proper...

  10. Structure and properties of compositions based on petroleum sulfonic acids

    Energy Technology Data Exchange (ETDEWEB)

    Tutorskii, I.A.; Sultanova, A.S.; Belkina, E.V.; Fomin, A.G. [Lomonosov Academy of Fine Chemical Technology, Moscow (Russian Federation)

    1995-03-01

    Colloidal characteristics of compositions based on petroleum sulfonic acids were studied. Neutralized heavy oil residue exhibits surface-active properties and contains an ultradisperse filler. Analysis of the compositions by size-exclusion-chromatography shows deep structural changes in the heavy acid residue upon neutralization with calcium carbonate.

  11. Carbon Fiber Reinforced Carbon Composite Valve for an Internal Combustion Engine

    Science.gov (United States)

    Rivers, H. Kevin (Inventor); Ransone, Philip O. (Inventor); Northam, G. Burton (Inventor)

    1999-01-01

    A carbon fiber reinforced carbon composite valve for internal combustion engines and the like formed of continuous carbon fibers throughout the valve's stem and head is disclosed. The valve includes braided carbon fiber material over axially aligned unidirectional carbon fibers forming a valve stem; the braided and unidirectional carbon fibers being broomed out at one end of the valve stem forming the shape of the valve head; the valve-shaped structure being densified and rigidized with a matrix of carbon containing discontinuous carbon fibers: and the finished valve being treated to resist oxidation. Also disclosed is a carbon matrix plug containing continuous and discontinuous carbon fibers and forming a net-shape valve head acting as a mandrel over which the unidirectional and braided carbon fibers are formed according to textile processes. Also disclosed are various preform valves and processes for making finished and preform carbon fiber reinforced carbon composite valves.

  12. Structural experiments with ice (composite) shells

    NARCIS (Netherlands)

    Belis, J.; Martens, K.; Van Lancker, B.; Pronk, A.; Zingoni, Alphose

    2016-01-01

    ABSTRACT: Ice can be a very suitable building material for temporary structures in a freezing environment. When water, mixed with small fibre reinforcements, is sprayed onto an inflatable membrane structure in suitable cold outdoor conditions, a thin shell is formed which increases thickness layer

  13. Composite Structure Monitoring using Direct Write Sensors, Phase II

    Data.gov (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...

  14. Band Structure Characteristics of Nacreous Composite Materials with Various Defects

    Science.gov (United States)

    Yin, J.; Zhang, S.; Zhang, H. W.; Chen, B. S.

    2016-06-01

    Nacreous composite materials have excellent mechanical properties, such as high strength, high toughness, and wide phononic band gap. In order to research band structure characteristics of nacreous composite materials with various defects, supercell models with the Brick-and-Mortar microstructure are considered. An efficient multi-level substructure algorithm is employed to discuss the band structure. Furthermore, two common systems with point and line defects and varied material parameters are discussed. In addition, band structures concerning straight and deflected crack defects are calculated by changing the shear modulus of the mortar. Finally, the sensitivity of band structures to the random material distribution is presented by considering different volume ratios of the brick. The results reveal that the first band gap of a nacreous composite material is insensitive to defects under certain conditions. It will be of great value to the design and synthesis of new nacreous composite materials for better dynamic properties.

  15. floristic composition and structure of the dry afromontane forest at ...

    African Journals Online (AJOL)

    ADMIN

    Key words/phrases: Bale Mountains, floristic composition, plant community, vegetation structure. INTRODUCTION .... from ground was estimated for each tree and shrub species by ...... and environmental factors characterizing coffee forests in ...

  16. Composites

    International Nuclear Information System (INIS)

    Kasen, M.B.

    1983-01-01

    This chapter discusses the roles of composite laminates and aggregates in cryogenic technology. Filamentary-reinforced composites are emphasized because they are the most widely used composite materials. Topics considered include composite systems and terminology, design and fabrication, composite failure, high-pressure reinforced plastic laminates, low-pressure reinforced plastics, reinforced metals, selectively reinforced structures, the effect of cryogenic temperatures, woven-fabric and random-mat composites, uniaxial fiber-reinforced composites, composite joints in cryogenic structures, joining techniques at room temperature, radiation effects, testing laminates at cryogenic temperatures, static and cyclic tensile testing, static and cyclic compression testing, interlaminar shear testing, secondary property tests, and concrete aggregates. It is suggested that cryogenic composite technology would benefit from the development of a fracture mechanics model for predicting the fitness-for-purpose of polymer-matrix composite structures

  17. Structural Acoustic Physics Based Modeling of Curved Composite Shells

    Science.gov (United States)

    2017-09-19

    NUWC-NPT Technical Report 12,236 19 September 2017 Structural Acoustic Physics -Based Modeling of Curved Composite Shells Rachel E. Hesse...SUBTITLE Structural Acoustic Physics -Based Modeling of Curved Composite Shells 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...study was to use physics -based modeling (PBM) to investigate wave propagations through curved shells that are subjected to acoustic excitation. An

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

    International Nuclear Information System (INIS)

    Rusmin, Ruhaida; Sarkar, Binoy; Liu, Yanju; McClure, Stuart; Naidu, Ravi

    2015-01-01

    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"−"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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rusmin, Ruhaida, E-mail: ruhaida.rusmin@mymail.unisa.edu.au [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: binoy.sarkar@unisa.edu.au [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: Ravi.Naidu@newcastle.edu.au [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)

    2015-10-30

    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.

  20. Effects of host cell sterol composition upon internalization of Yersinia pseudotuberculosis and clustered β1 integrin.

    Science.gov (United States)

    Kim, JiHyun; Fukuto, Hana S; Brown, Deborah A; Bliska, James B; London, Erwin

    2018-01-26

    Yersinia pseudotuberculosis is a foodborne pathogenic bacterium that causes acute gastrointestinal illness, but its mechanisms of infection are incompletely described. We examined how host cell sterol composition affected Y. pseudotuberculosis uptake. To do this, we depleted or substituted cholesterol in human MDA-MB-231 epithelial cells with various alternative sterols. Decreasing host cell cholesterol significantly reduced pathogen internalization. When host cell cholesterol was substituted with various sterols, only desmosterol and 7-dehydrocholesterol supported internalization. This specificity was not due to sterol dependence of bacterial attachment to host cells, which was similar with all sterols studied. Because a key step in Y. pseudotuberculosis internalization is interaction of the bacterial adhesins invasin and YadA with host cell β1 integrin, we compared the sterol dependence of wildtype Y. pseudotuberculosis internalization with that of Δ inv , Δ yadA , and Δ inv Δ yadA mutant strains. YadA deletion decreased bacterial adherence to host cells, whereas invasin deletion had no effect. Nevertheless, host cell sterol substitution had a similar effect on internalization of these bacterial deletion strains as on the wildtype bacteria. The Δ inv Δ yadA double mutant adhered least to cells and so was not significantly internalized. The sterol structure dependence of Y. pseudotuberculosis internalization differed from that of endocytosis, as monitored using antibody-clustered β1 integrin and previous studies on other proteins, which had a more permissive sterol dependence. This study suggests that agents could be designed to interfere with internalization of Yersinia without disturbing endocytosis. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Foundations of compositional models: structural properties

    Czech Academy of Sciences Publication Activity Database

    Jiroušek, Radim; Kratochvíl, Václav

    2015-01-01

    Roč. 44, č. 1 (2015), s. 2-25 ISSN 0308-1079 R&D Projects: GA ČR GA13-20012S Grant - others:GA ČR(CZ) GAP403/12/2175 Program:GA Institutional support: RVO:67985556 Keywords : multidimensional distribution * conditional independence * composition * semigraphoid properties * running intersection property Subject RIV: BA - General Mathematics Impact factor: 1.677, year: 2015 http://library.utia.cas.cz/separaty/2015/MTR/jirousek-0442412.pdf

  2. Graphites and composites irradiations for gas cooled reactor core structures

    International Nuclear Information System (INIS)

    Van der Laan, J.G.; Vreeling, J.A.; Buckthorpe, D.E.; Reed, J.

    2008-01-01

    Full text of publication follows. Material investigations are undertaken as part of the European Commission 6. Framework Programme for helium-cooled fission reactors under development like HTR, VHTR, GCFR. The work comprises a range of activities, from (pre-)qualification to screening of newly designed materials. The High Flux Reactor at Petten is the main test bed for the irradiation test programmes of the HTRM/M1, RAPHAEL and ExtreMat Integrated Projects. These projects are supported by the European Commission 5. and 6. Framework Programmes. To a large extent they form the European contribution to the Generation-IV International Forum. NRG is also performing a Materials Test Reactor project to support British Energy in preparing extended operation of their Advanced Gas-cooled Reactors (AGR). Irradiations of commercial and developmental graphite grades for HTR core structures are undertaken in the range of 650 to 950 deg C, with a view to get data on physical and mechanical properties that enable engineering design. Various C- and SiC-based composite materials are considered for support structures or specific components like control rods. Irradiation test matrices are chosen to cover commercial materials, and to provide insight on the behaviour of various fibre and matrix types, and the effects of architecture and manufacturing process. The programme is connected with modelling activities to support data trending, and improve understanding of the material behaviour and micro-structural evolution. The irradiation programme involves products from a large variety of industrial and research partners, and there is strong interaction with other high technology areas with extreme environments like space, electronics and fusion. The project on AGR core structures graphite focuses on the effects of high dose neutron irradiation and simultaneous radiolytic oxidation in a range of 350 to 450 deg C. It is aimed to provide data on graphite properties into the parameter space

  3. Use of a perfume composition as a fuel for internal combustion engines

    NARCIS (Netherlands)

    2013-01-01

    The present invention relates to fuel compositions containing perfume fractions, that is to say compositions of fragrance materials, and to the use of such perfume fractions containing fuel compositions to provide a fuel for internal combustion engines and burners. According to the present fuel

  4. Structures and Performance of Graphene/Polyimide Composite Graphite Fibers

    Directory of Open Access Journals (Sweden)

    LI Na

    2017-09-01

    Full Text Available Dry-wet spinning process was used to gain graphene oxide/polyimide composite fibers, then graphene/polyimide composite carbon and graphite fibers were obtained through carbonized and graphitized. Different graphene oxide contents of the composite carbon and graphite fibers were measured by thermal gravimetric analysis, Raman, mechanical properties, electrical properties,SEM and so on. The results show that when the GO content is 0.3%(mass fraction,the same below, the thermal property of the graphene oxide/polyimide composite fibers is the best. The mechanical and electrical properties are obriously improved by the addition of GO, graphitization degree also increases. When the composite carbon fibers are treated at 2800℃, GO content increases to 2.0%, the thermal conductivity of the composite graphite fibers reaches 435.57W·m-1·K-1 and cross-section structures of carbon fibers are more compact.

  5. Versatile Micromechanics Model for Multiscale Analysis of Composite Structures

    Science.gov (United States)

    Kwon, Y. W.; Park, M. S.

    2013-08-01

    A general-purpose micromechanics model was developed so that the model could be applied to various composite materials such as reinforced by particles, long fibers and short fibers as well as those containing micro voids. Additionally, the model can be used with hierarchical composite materials. The micromechanics model can be used to compute effective material properties like elastic moduli, shear moduli, Poisson's ratios, and coefficients of thermal expansion for the various composite materials. The model can also calculate the strains and stresses at the constituent material level such as fibers, particles, and whiskers from the composite level stresses and strains. The model was implemented into ABAQUS using the UMAT option for multiscale analysis. An extensive set of examples are presented to demonstrate the reliability and accuracy of the developed micromechanics model for different kinds of composite materials. Another set of examples is provided to study the multiscale analysis of composite structures.

  6. In-service inspection guidelines for composite aerospace structures

    International Nuclear Information System (INIS)

    Heida, Jaap H.; Platenkamp, Derk J.

    2012-01-01

    The in-service inspection of composite aerospace structures is reviewed, using the results of a evaluation of promising, mobile non-destructive inspection (NDI) methods. The evaluation made use of carbon fibre reinforced specimens representative for primary composite aerospace structures, including relevant damage types such as impact damage, delaminations and disbonds. A range of NDI methods were evaluated such as visual inspection, vibration analysis, phased array ultrasonic inspection, shearography and thermography inspection. Important aspects of the evaluation were the capability for defect detection and characterization, portability of equipment, field of view, couplant requirements, speed of inspection, level of training required and the cost of equipment. The paper reviews the damage tolerance design approach for composites, and concludes with guidelines for the in-service inspection of composite aerospace structures.

  7. 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...... work this set-up should be improved such that the modelled pressure can be validated. For tests performed with a 250g charge load comparisons with model data showed poor agreement. This was found to be due to improper design of the modelled laminate panels, where the layer interface delamination...

  8. Structural characterization of degradation of ODS composite using SEM and XRM techniques

    Directory of Open Access Journals (Sweden)

    Oladayo OLANIRAN

    2017-07-01

    Full Text Available The structural characteristics and mechanisms of corrosion and wear of oxide dispersion strengthened stainless steel composite were investigated. Insitu synchrotron x-ray tomography was used as experimental technique for degradation analysis from the corrosion and tribology studies. Corrosion study was carried out using potential dynamic techniques while the tribology experiments were conducted using a tribometer with ball on disc method. The x-ray micro tomography data gave chronological description of crack initiation and propagation in 3D and revealed that pitting did not result from the oxide inclusion. The results also revealed the surface imaging capacity of SEM and XRM’s capability for imaging internal structures. Taber index measurement was used as a complimenting tool for tribology measurements. Tribological behaviour of the sinter Oxide Dispersion Strengthened (ODS steel composite depends on both the composition of the composite and the loading system.

  9. On the Mechanical Behavior of Advanced Composite Material Structures

    Science.gov (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.

  10. Failure Analysis of Composite Structure Materials.

    Science.gov (United States)

    1987-05-27

    cracking intersected the trailing edge of the skin at a radius for a runout of an overhanging tab. Extensive delamination was evident or each side of...structure with an abrasive cutoff wheel to minimize artifacts. Detailed crack mapping of the delamination surfaces was performed by optical microscopy

  11. 75 FR 793 - Damage Tolerance and Fatigue Evaluation of Composite Rotorcraft Structures

    Science.gov (United States)

    2010-01-06

    ... metal structures are different. Composites are complex materials that have unique advantages in fatigue... stiffness, dynamic behavior, loads, and functional performance of composite structures. In the existing rule... and Fatigue Evaluation of Composite Rotorcraft Structures AGENCY: Federal Aviation Administration (FAA...

  12. Project in fiscal 2000 of developing international standards for supporting new industries. Standardization of method for evaluating mechanical stress of composite structures for aerospace use; 2000 nendo shinki sangyo shiengata kokusai hyojun kaihatsu jigyo seika hokokusho. Koku uchuyo sentan fukugozai no kyodo hyoka hoho no hyojunka

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    R and D has been performed on methods to repair composite structures used in aerospace application, and on stress evaluation on repaired portions, targeting at establishment of international standardization. This paper summarizes the achievements in fiscal 2000. The current fiscal year has executed surveys on repair methods, selection of the repair methods, evaluation on the repairing processes, and compression strength evaluation on test samples given repairs. The method for repairing the sandwich-structure composite members was selected as a result surveys and discussions on published literatures. For the evaluation test on the repairing processes, specific repairing processes were established with reference to the result of surveys on the repair methods, which were applied to test samples having been given damages. In addition, discussions were given also on non-destructive inspection methods for sandwich panels. Regarding the strength test for repaired portions, a compression strength test was performed on test samples repaired by using adhesive after having been given damages, wherein data related to compression strength were obtained. Furthermore, a system was developed to analyze the scarf-like adhesive-repaired potions by using the two-dimensional finite element method model. (NEDO)

  13. Transition from glass to graphite in manufacture of composite aircraft structure

    Science.gov (United States)

    Buffum, H. E.; Thompson, V. S.

    1978-01-01

    The transition from fiberglass reinforced plastic composites to graphite reinforced plastic composites is described. Structural fiberglass design and manufacturing background are summarized. How this experience provides a technology base for moving into graphite composite secondary structure and then to composite primary structure is considered. The technical requirements that must be fulfilled in the transition from glass to graphite composite structure are also included.

  14. Characterization and manufacture of braided composites for large commercial aircraft structures

    Science.gov (United States)

    Fedro, Mark J.; Willden, Kurtis

    1992-01-01

    Braided composite materials, one of the advanced material forms which is under investigation in Boeing's ATCAS program, have been recognized as a potential cost-effective material form for fuselage structural elements. Consequently, there is a strong need for more knowledge in the design, manufacture, test, and analysis of textile structural composites. The overall objective of this work is to advance braided composite technology towards applications to a large commercial transport fuselage. This paper summarizes the mechanics of materials and manufacturing demonstration results which have been obtained in order to acquire an understanding of how braided composites can be applied to a commercial fuselage. Textile composites consisting of 1D, 2D triaxial, and 3D braid patterns with thermoplastic and two RTM resin systems were investigated. The structural performance of braided composites was evaluated through an extensive mechanical test program. Analytical methods were also developed and applied to predict the following: internal fiber architectures, stiffnesses, fiber stresses, failure mechanisms, notch effects, and the entire history of failure of the braided composites specimens. The applicability of braided composites to a commercial transport fuselage was further assessed through a manufacturing demonstration. Three foot fuselage circumferential hoop frames were manufactured to demonstrate the feasibility of consistently producing high quality braided/RTM composite primary structures. The manufacturing issues (tooling requirements, processing requirements, and process/quality control) addressed during the demonstration are summarized. The manufacturing demonstration in conjunction with the mechanical test results and developed analytical methods increased the confidence in the ATCAS approach to the design, manufacture, test, and analysis of braided composites.

  15. Vegetation structure and floristic composition of Gergeda Anfillo ...

    African Journals Online (AJOL)

    Vegetation structure and floristic composition of Gergeda Anfillo Forest, West Ethiopia. ... Moreover, the forest housed 10 of the 24 national priority tree species and four plant communities were identified by cluster analysis. Structural analysis revealed that the forest is dominated by small sized trees and shrubs.

  16. Structure, composition and mechanical properties of the silk fibres of ...

    Indian Academy of Sciences (India)

    The silk egg case and orb web of spiders are elaborate structures that are assembled from a number of components. We analysed the structure, the amino acid and fibre compositions, and the tensile properties of the silk fibres of the egg case of Nephila clavata. SEM shows that the outer and inner covers of the egg case ...

  17. Fluid Structure Interaction Effect on Sandwich Composite Structures

    Science.gov (United States)

    2011-09-01

    far back as ancient Egyptian times in the use of straw and bricks, or more recently in the last century with the use of steel rebar in concrete ...construction of sandwich composites; however, this particular material was selected for its uniform pattern and translucent qualities after it is wetted out...excellent fire retardant and corrosion resistant qualities making it a natural selection for shipboard applications. The same translucent qualities

  18. Study of Comets Composition and Structure

    Science.gov (United States)

    Khalaf, S. Z.; Selman, A. A.; Ali, H. S.

    2008-12-01

    The present paper focuses on the nature of the different interactions between cometary nucleus and tail with solar wind. The dynamics of the comet will impose many features that provide unique behavior of the comet when entering the solar system. These features are reviewed in this paper and few investigations are made. The calculations made in this work represent the analysis and interpretation of the different features of the comet, such as perihelion and eccentricity dependence on the gas production rate, and the dependence of the latter on the composition of the comet nucleus. The dependences of the heliocentric, bow shock, contact surface, and stand-off distances with gas production rate for many types of comets that cover linear and non-linear types are studied in this work. Important results are obtained which indicated the different physical interactions between cometary ions and solar wind. Furthermore, the important relation between mean molecular weight and gas production rate are analyzed and studied in this work and a conclusion is made that, as the gas production rate increases, the mean molecular weight will decrease exponentially. A detailed discussion for this unique relation is given.

  19. Recent developments of discrete material optimization of laminated composite structures

    DEFF Research Database (Denmark)

    Lund, Erik; Sørensen, Rene

    2015-01-01

    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...... of plies in a laminated composite structure. The conceptual combinatorial design problem is relaxed to a continuous problem such that well-established gradient based optimization techniques can be applied, and the optimization problem is solved on basis of interpolation schemes with penalization...

  20. Ink composition for making a conductive silver structure

    Science.gov (United States)

    Walker, Steven B.; Lewis, Jennifer A.

    2016-10-18

    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 120.degree. C. or less.

  1. Irradiation-induced structure and property changes in tokamak plasma-facing, carbon-carbon composites

    International Nuclear Information System (INIS)

    Burchell, T.D.

    1994-01-01

    Carbon-carbon composites are an attractive choice for fusion reactor plasma-facing components because of their low atomic number, superior thermal shock resistance, and low neutron activation. Next generation plasma fusion reactors, such as the International Thermonuclear Experimental Reactor (ITER), will require advanced carbon-carbon composite materials possessing high thermal conductivity to manage the anticipated severe heat loads. Moreover, ignition machines such as ITER will produce large neutron fluxes. Consequently, the influence of neutron damage on the structure and properties of carbon-carbon composite materials must be evaluated. Data from two irradiation experiments are reported and discussed here. Carbon-carbon composite materials were irradiated in target capsules in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). A peak damage dose of 4.7 displacements per atom (dpa) at 600 degree C was attained. The carbon materials irradiated included uni-directional, two-directional, and three-directional carbon-carbon composites. Dimensional changes are reported for the composite materials and are related to single crystal dimensional changes through fiber and composite structural models. Moreover, the irradiation-induced dimensional changes are reported and discussed in terms of their architecture, fiber type, and graphitization temperature. The effect of neutron irradiation on thermal conductivity of two three-directional, carbon-carbon composites is reported and the recovery of thermal conductivity due to thermal annealing is discussed

  2. Relativistic Processes and the Internal Structure of Neutron Stars

    International Nuclear Information System (INIS)

    Alvarez-Castillo, D. E.; Kubis, S.

    2011-01-01

    Models for the internal composition of Dense Compact Stars are reviewed as well as macroscopic properties derived by observations of relativistic processes. Modeling of pure neutron matter Neutron Stars is presented and crust properties are studied by means of a two fluid model.

  3. In-situ poling and structurization of piezoelectric particulate composites.

    Science.gov (United States)

    Khanbareh, H; van der Zwaag, S; Groen, W A

    2017-11-01

    Composites of lead zirconate titanate particles in an epoxy matrix are prepared in the form of 0-3 and quasi 1-3 with different ceramic volume contents from 10% to 50%. Two different processing routes are tested. Firstly a conventional dielectrophoretic structuring is used to induce a chain-like particle configuration, followed by curing the matrix and poling at a high temperature and under a high voltage. Secondly a simultaneous combination of dielectrophoresis and poling is applied at room temperature while the polymer is in the liquid state followed by subsequent curing. This new processing route is practiced in an uncured thermoset system while the polymer matrix still possess a relatively high electrical conductivity. Composites with different degrees of alignment are produced by altering the magnitude of the applied electric field. A significant improvement in piezoelectric properties of quasi 1-3 composites can be achieved by a combination of dielectrophoretic alignment of the ceramic particles and poling process. It has been observed that the degree of structuring as well as the functional properties of the in-situ structured and poled composites enhance significantly compared to those of the conventionally manufactured structured composites. Improving the alignment quality enhances the piezoelectric properties of the particulate composites.

  4. Present status of SiCf/SiC composites as low-activation structural materials of fusion reactor in Japan

    International Nuclear Information System (INIS)

    Kohyama, A.; Katoh, Y.; Hasegawa, A.; Noda, T.

    2001-01-01

    The outline of research subjects on SiCf/SiC composites to apply to the structural components of fusion reactors are described and present status on material development of SiCf/SiC composites in Japan is reviewed. Irradiation experiments of the composites using fission reactors conducted by international collaborations to clarify their radiation response and to optimize the fabrication processes are introduced. (author)

  5. Boreal Forests of Kamchatka: Structure and Composition

    OpenAIRE

    Eichhorn, Markus P.

    2010-01-01

    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-domi...

  6. Structurally integrated fiber optic damage assessment system for composite materials.

    Science.gov (United States)

    Measures, R M; Glossop, N D; Lymer, J; Leblanc, M; West, J; Dubois, S; Tsaw, W; Tennyson, R C

    1989-07-01

    Progress toward the development of a fiber optic damage assessment system for composite materials is reported. This system, based on the fracture of embedded optical fibers, has been characterized with respect to the orientation and location of the optical fibers in the composite. Together with a special treatment, these parameters have been tailored to yield a system capable of detecting the threshold of damage for various impacted Kevlar/epoxy panels. The technique has been extended to measure the growth of a damage region which could arise from either impact, manufacturing flaws, or static overloading. The mechanism of optical fiber fracture has also been investigated. In addition, the influence of embedded optical fibers on the tensile and compressive strength of the composite material has been studied. Image enhanced backlighting has been shown to be a powerful and convenient method of assessing internal damage to translucent composite materials.

  7. Versatile hydrothermal synthesis of one-dimensional composite structures

    Science.gov (United States)

    Luo, Yonglan

    2008-12-01

    In this paper we report on a versatile hydrothermal approach developed to fabricate one-dimensional (1D) composite structures. Sulfur and selenium formed liquid and adsorbed onto microrods as droplets and subsequently reacted with metallic ion in solution to produce nanoparticles-decorated composite microrods. 1D composites including ZnO/CdS, ZnO/MnS, ZnO/CuS, ZnO/CdSe, and FeOOH/CdS were successfully made using this hydrothermal strategy and the growth mechanism was also discussed. This hydrothermal strategy is simple and green, and can be extended to the synthesis of various 1D composite structures. Moreover, the interaction between the shell nanoparticles and the one-dimensional nanomaterials were confirmed by photoluminescence investigation of ZnO/CdS.

  8. Hybrid Bridge Structures Made of Frp Composite and Concrete

    Science.gov (United States)

    Rajchel, Mateusz; Siwowski, Tomasz

    2017-09-01

    Despite many advantages over the conventional construction materials, the contemporary development of FRP composites in bridge engineering is limited due to high initial cost, low stiffness (in case of glass fibers) and sudden composite failure mode. In order to reduce the given limitations, mixed (hybrid) solutions connecting the FRP composites and conventional construction materials, including concrete, have been tested in many countries for 20 years. Shaping the hybrid structures based on the attributes of particular materials, aims to increase stiffness and reduce cost without losing the carrying capacity, lightness and easiness of bridges that includes such hybrid girders, and to avoid the sudden dangerous failure mode. In the following article, the authors described examples of hybrid road bridges made of FRP composite and concrete within the time of 20 years and presented the first Polish hybrid FRP-concrete road bridge. Also, the directions of further research, necessary to spread these innovative, advanced and sustainable bridge structures were indicated.

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

    Directory of Open Access Journals (Sweden)

    Filiberto González Garcia

    2011-12-01

    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.

  10. International Good Market Segmentation and Financial Market Structure

    OpenAIRE

    Basak, Suleyman; Croitoru, Benjamin

    2003-01-01

    While financial markets have recently become more complete and international capital flows well liberalized, markets for goods remain segmented. To investigate how more complete security markets may relieve the effects of this segmentation, we examine a series of two-country economies with internationally segmented good markets, distinguished by the available financial securities. We show that, under heterogeneity within countries, the financial structure matters: even with internationally co...

  11. 22 CFR 96.32 - Internal structure and oversight.

    Science.gov (United States)

    2010-04-01

    ... Accreditation and Approval Licensing and Corporate Governance § 96.32 Internal structure and oversight. (a) The... number of such other provider; and (3) The name, address, and phone number of any entity it uses or...

  12. Electronic structure and physical properties of 13C carbon composite

    OpenAIRE

    Zhmurikov, Evgenij

    2015-01-01

    This review is devoted to the application of graphite and graphite composites in science and technology. Structure and electrical properties, as so technological aspects of producing of high-strength artificial graphite and dynamics of its destruction are considered. These type of graphite are traditionally used in the nuclear industry. Author was focused on the properties of graphite composites based on carbon isotope 13C. Generally, the review relies on the original results and concentrates...

  13. Low Velocity Impact Properties of Aluminum Foam Sandwich Structural Composite

    Directory of Open Access Journals (Sweden)

    ZHAO Jin-hua

    2018-01-01

    Full Text Available Sandwich structural composites were prepared by aluminum foam as core materials with basalt fiber(BF and ultra-high molecular weight polyethylene(UHMWPE fiber composite as faceplate. The effect of factors of different fiber type faceplates, fabric layer design and the thickness of the corematerials on the impact properties and damage mode of aluminum foam sandwich structure was studied. The impact properties were also analyzed to compare with aluminum honeycomb sandwich structure. The results show that BF/aluminum foam sandwich structural composites has bigger impact damage load than UHMWPE/aluminum foam sandwich structure, but less impact displacement and energy absorption. The inter-layer hybrid fabric design of BF and UHMWPE has higher impact load and energy absorption than the overlay hybrid fabric design faceplate sandwich structure. With the increase of the thickness of aluminum foam,the impact load of the sandwich structure decreases, but the energy absorption increases. Aluminum foam sandwich structure has higher impact load than the aluminum honeycomb sandwich structure, but smaller damage energy absorption; the damage mode of aluminum foam core material is mainly the fracture at the impact area, while aluminum honeycomb core has obvious overall compression failure.

  14. Radiation damage in carbon-carbon composites: Structure and property effects

    International Nuclear Information System (INIS)

    Burchell, T.D.

    1995-01-01

    Carbon-carbon composites are an attractive choice for fusion reactor plasma facing components because of their low atomic number, superior thermal shock resistance, and low neutron activation. Next generation tokamak reactors such as the International Thermonuclear Experimental Reactor (ITER), will require high thermal conductivity carbon-carbon composites and other materials, such as beryllium, to protect their plasma facing components from the anticipated high heat fluxes. Moreover, ignition machines such as ITER will produce a large neutron flux. Consequently, the influence of neutron damage on the structure and properties of carbon-carbon composite materials must be evaluated. Data from two irradiation experiments are reported and discussed here. Carbon-carbon composite materials were irradiated in target capsules in the High Flux Isotope Reactor (HAIR) at Oak Ridge National Laboratory (ORAL). A peak damage dose of 4.7 displacements per atom (da) at an irradiation temperature of ∼600 degrees C was attained. The carbon materials irradiated here included unidirectional, two- directional, and three-directional carbon-carbon composites. Irradiation induced dimensional changes are reported for the materials and related to single crystal dimensional changes through fiber and composite structural models. Moreover, carbon-carbon composite material dimensional changes are discussed in terms of their architecture, fiber type, and graphitization temperature. Neutron irradiation induced reductions in the thermal conductivity of two, three-directional carbon-carbon composites are reported, and the recovery of thermal conductivity due to thermal annealing is demonstrated. Irradiation induced strength changes are reported for several carbon-carbon composite materials and are explained in terms of in-crystal and composite structural effects

  15. Boreal Forests of Kamchatka: Structure and Composition

    Directory of Open Access Journals (Sweden)

    Markus P. Eichhorn

    2010-09-01

    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.

  16. Shear wave propagation in piezoelectric-piezoelectric composite layered structure

    Directory of Open Access Journals (Sweden)

    Anshu Mli Gaur

    Full Text Available The propagation behavior of shear wave in piezoelectric composite structure is investigated by two layer model presented in this approach. The composite structure comprises of piezoelectric layers of two different materials bonded alternatively. Dispersion equations are derived for propagation along the direction normal to the layering and in direction of layering. It has been revealed that thickness and elastic constants have significant influence on propagation behavior of shear wave. The phase velocity and wave number is numerically calculated for alternative layer of Polyvinylidene Difluoride (PVDF and Lead Zirconate Titanate (PZT-5H in composite layered structure. The analysis carried out in this paper evaluates the effect of volume fraction on the phase velocity of shear wave.

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

    CERN Document Server

    Kassapoglou, Christos

    2010-01-01

    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

  18. Composition-Structure-Property Relationships in Boroaluminosilicate Glasses

    DEFF Research Database (Denmark)

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

    2012-01-01

    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......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...

  19. Fracture mechanisms and fracture control in composite structures

    Science.gov (United States)

    Kim, Wone-Chul

    Four basic failure modes--delamination, delamination buckling of composite sandwich panels, first-ply failure in cross-ply laminates, and compression failure--are analyzed using linear elastic fracture mechanics (LEFM) and the J-integral method. Structural failures, including those at the micromechanical level, are investigated with the aid of the models developed, and the critical strains for crack propagation for each mode are obtained. In the structural fracture analyses area, the fracture control schemes for delamination in a composite rib stiffener and delamination buckling in composite sandwich panels subjected to in-plane compression are determined. The critical fracture strains were predicted with the aid of LEFM for delamination and the J-integral method for delamination buckling. The use of toughened matrix systems has been recommended for improved damage tolerant design for delamination crack propagation. An experimental study was conducted to determine the onset of delamination buckling in composite sandwich panel containing flaws. The critical fracture loads computed using the proposed theoretical model and a numerical computational scheme closely followed the experimental measurements made on sandwich panel specimens of graphite/epoxy faceskins and aluminum honeycomb core with varying faceskin thicknesses and core sizes. Micromechanical models of fracture in composites are explored to predict transverse cracking of cross-ply laminates and compression fracture of unidirectional composites. A modified shear lag model which takes into account the important role of interlaminar shear zones between the 0 degree and 90 degree piles in cross-ply laminate is proposed and criteria for transverse cracking have been developed. For compressive failure of unidirectional composites, pre-existing defects play an important role. Using anisotropic elasticity, the stress state around a defect under a remotely applied compressive load is obtained. The experimentally

  20. International conference on composite materials and energy: Proceedings. Enercomp 95

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    World demand for composite materials is continuously increasing. High strength and rigidity, associated with light weight, are the key factors for composites' success. These materials find numerous applications in all sectors of industry. Presently, a sector of particular interest in terms of demand for composite materials is the energy industry. More and more applications are found in the field of the forms of energy: electrical, petroleum, gas, nuclear, solar and wind. The topics addressed in various sessions of the conference cover potential applications of the entire range of polymer, metal and ceramic composites in all sectors of energy. Papers are divided into sessions covering the following topics: properties; design and analysis; fracture; fatigue and long-term performance; new materials; innovative processing; liquid molding; joining and repairs; radiation curing; recycling; development in ceramic materials; innovations in metallic materials; metal-matrix composites; nondestructive evaluation; energy savings in transportation; pressure vessels and piping; wind energy applications; electrical components; concrete applications; power plant applications; and new materials in the energy field. Most of the papers have been processed separately for inclusion on the data base

  1. Development of Textile Reinforced Composites for Aircraft Structures

    Science.gov (United States)

    Dexter, H. Benson

    1998-01-01

    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.

  2. Experimental identification of smart material coupling effects in composite structures

    International Nuclear Information System (INIS)

    Chesne, S; Jean-Mistral, C; Gaudiller, L

    2013-01-01

    Smart composite structures have an enormous potential for industrial applications, in terms of mass reduction, high material resistance and flexibility. The correct characterization of these complex structures is essential for active vibration control or structural health monitoring applications. The identification process generally calls for the determination of a generalized electromechanical coupling coefficient. As this process can in practice be difficult to implement, an original approach, presented in this paper, has been developed for the identification of the coupling effects of a smart material used in a composite curved beam. The accuracy of the proposed identification technique is tested by applying active modal control to the beam, using a reduced model based on this identification. The studied structure was as close to reality as possible, and made use of integrated transducers, low-cost sensors, clamped boundary conditions and substantial, complex excitation sources. PVDF (polyvinylidene fluoride) and MFC (macrofiber composite) transducers were integrated into the composite structure, to ensure their protection from environmental damage. The experimental identification described here was based on a curve fitting approach combined with the reduced model. It allowed a reliable, powerful modal control system to be built, controlling two modes of the structure. A linear quadratic Gaussian algorithm was used to determine the modal controller–observer gains. The selected modes were found to have an attenuation as strong as −13 dB in experiments, revealing the effectiveness of this method. In this study a generalized approach is proposed, which can be extended to most complex or composite industrial structures when they are subjected to vibration. (paper)

  3. Composite Structure Modeling and Analysis of Advanced Aircraft Fuselage Concepts

    Science.gov (United States)

    Mukhopadhyay, Vivek; Sorokach, Michael R.

    2015-01-01

    NASA Environmentally Responsible Aviation (ERA) project and the Boeing Company are collabrating to advance the unitized damage arresting composite airframe technology with application to the Hybrid-Wing-Body (HWB) aircraft. The testing of a HWB fuselage section with Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) construction is presently being conducted at NASA Langley. Based on lessons learned from previous HWB structural design studies, improved finite-element models (FEM) of the HWB multi-bay and bulkhead assembly are developed to evaluate the performance of the PRSEUS construction. In order to assess the comparative weight reduction benefits of the PRSEUS technology, conventional cylindrical skin-stringer-frame models of a cylindrical and a double-bubble section fuselage concepts are developed. Stress analysis with design cabin-pressure load and scenario based case studies are conducted for design improvement in each case. Alternate analysis with stitched composite hat-stringers and C-frames are also presented, in addition to the foam-core sandwich frame and pultruded rod-stringer construction. The FEM structural stress, strain and weights are computed and compared for relative weight/strength benefit assessment. The structural analysis and specific weight comparison of these stitched composite advanced aircraft fuselage concepts demonstrated that the pressurized HWB fuselage section assembly can be structurally as efficient as the conventional cylindrical fuselage section with composite stringer-frame and PRSEUS construction, and significantly better than the conventional aluminum construction and the double-bubble section concept.

  4. Damping Analysis of Cylindrical Composite Structures with Enhanced Viscoelastic Properties

    Science.gov (United States)

    Kliem, Mathias; Høgsberg, Jan; Vanwalleghem, Joachim; Filippatos, Angelos; Hoschützky, Stefan; Fotsing, Edith-Roland; Berggreen, Christian

    2018-04-01

    Constrained layer damping treatments are widely used in mechanical structures to damp acoustic noise and mechanical vibrations. A viscoelastic layer is thereby applied to a structure and covered by a stiff constraining layer. When the structure vibrates in a bending mode, the viscoelastic layer is forced to deform in shear mode. Thus, the vibration energy is dissipated as low grade frictional heat. This paper documents the efficiency of passive constrained layer damping treatments for low frequency vibrations of cylindrical composite specimens made of glass fibre-reinforced plastics. Different cross section geometries with shear webs have been investigated in order to study a beneficial effect on the damping characteristics of the cylinder. The viscoelastic damping layers are placed at different locations within the composite cylinder e.g. circumferential and along the neutral plane to evaluate the location-dependent efficiency of constrained layer damping treatments. The results of the study provide a thorough understanding of constrained layer damping treatments and an improved damping design of the cylindrical composite structure. The highest damping is achieved when placing the damping layer in the neutral plane perpendicular to the bending load. The results are based on free decay tests of the composite structure.

  5. International symposium on in vivo body composition studies: Program and abstracts

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    This booklet contains the program and individual abstracts for papers presented at the International symposium on in vivo body composition studies. The presentations were divided into five sessions. Individual abstracts were indexed for the Energy Data Base. (DT)

  6. DEVELOPMENT AND VALIDATION OF NUMERICAL METHOD FOR STRENGTH ANALYSIS OF LATTICE COMPOSITE FUSELAGE STRUCTURES

    Directory of Open Access Journals (Sweden)

    2016-01-01

    Full Text Available Lattice composite fuselage structures are developed as an alternative to conventional composite structures based on laminated skin and stiffeners. Structure layout of lattice structures allows to realize advantages of current composite materials to a maximal extent, at the same time minimizing their main shortcomings, that allows to provide higher weight efficiency for these structures in comparison with conventional analogues.Development and creation of lattice composite structures requires development of novel methods of strength anal- ysis, as conventional methods, as a rule, are aiming to strength analysis of thin-walled elements and do not allow to get confident estimation of local strength of high-loaded unidirectional composite ribs.In the present work the method of operative strength analysis of lattice composite structure is presented, based onspecialized FE-models of unidirectional composite ribs and their intersections. In the frames of the method, every rib is modeled by a caisson structure, consisting of arbitrary number of flanges and webs, modeled by membrane finite elements. Parameters of flanges and webs are calculated automatically from the condition of stiffness characteristics equality of real rib and the model. This method allows to perform local strength analysis of high-loaded ribs of lattice structure without use of here-dimensional finite elements, that allows to shorten time of calculations and sufficiently simplify the procedure of analysis of results of calculations.For validation of the suggested method, the results of experimental investigations of full-scale prototype of shell of lattice composite fuselage section have been used. The prototype of the lattice section was manufactured in CRISM and tested in TsAGI within the frames of a number of Russian and International scientific projects. The results of validation have shown that the suggested method allows to provide high operability of strength analysis, keeping

  7. International seminar on structural investigations on pulsed neutron sources. Proceedings

    International Nuclear Information System (INIS)

    Aksenov, V.L.; Balagurov, A.M.; Taran, Yu.V.

    1993-01-01

    The proceedings of the International seminar on structural investigations using pulsed neutron sources are presented. The seminar is dedicated to the memory of Dr. Yu.M. Ostanevich, a world acknowledged physicist. The problems of structural analysis using pulsed neutron source at the IBR-2 reactor are discussed

  8. Self-learning health monitoring algorithm in composite structures

    Science.gov (United States)

    Grassia, Luigi; Iannone, Michele; Califano, America; D'Amore, Alberto

    2018-02-01

    The paper describes a system that it is able of monitoring the health state of a composite structure in real time. The hardware of the system consists of a wire of strain sensors connected to a control unit. The software of the system elaborates the strain data and in real time is able to detect the presence of an eventual damage of the structures monitored with the strain sensors. The algorithm requires as input only the strains of the monitored structured measured on real time, i.e. those strains coming from the deformations of the composite structure due to the working loads. The health monitoring system does not require any additional device to interrogate the structure as often used in the literature, instead it is based on a self-learning procedure. The strain data acquired when the structure is healthy are used to set up the correlations between the strain in different positions of structure by means of neural network. Once the correlations between the strains in different position have been set up, these correlations act as a fingerprint of the healthy structure. In case of damage the correlation between the strains in the position of the structure near the damage will change due to the change of the stiffness of the structure caused by the damage. The developed software is able to recognize the change of the transfer function between the strains and consequently is able to detect the damage.

  9. Permeability and flammability study of composite sandwich structures for cryogenic applications

    Science.gov (United States)

    Bubacz, Monika

    Fiber reinforced plastics offer advantageous specific strength and stiffness compared to metals and has been identified as candidates for the reusable space transportation systems primary structures including cryogenic tanks. A number of carbon and aramid fiber reinforced plastics have been considered for the liquid hydrogen tanks. Materials selection is based upon mechanical properties and containment performance (long and short term) and upon manufacturing considerations. The liquid hydrogen tank carries shear, torque, end load, and bending moment due to gusts, maneuver, take-off, landing, lift, drag, and fuel sloshing. The tank is pressurized to about 1.5 atmosphere (14.6psi or 0.1 MPa) differential pressure and on ascent maintains the liquid hydrogen at a temperature of 20K. The objective of the research effort into lay the foundation for developing the technology required for reliable prediction of the effects of various design, manufacturing, and service parameters on the susceptibility of composite tanks to develop excessive permeability to cryogenic fuels. Efforts will be expended on developing the materials and structural concepts for the cryogenic tanks that can meet the functional requirements. This will include consideration for double wall composite sandwich structures, with inner wall to meet the cryogenic requirements. The structure will incorporate nanoparticles for properties modifications and developing barriers. The main effort will be extended to tank wall's internal skin design. The main requirements for internal composite stack are: (1) introduction of barrier film (e.g. honeycomb material paper sheet) to reduce the wall permeability to hydrogen, (2) introduction of nanoparticles into laminate resin to prevent micro-cracking or crack propagation. There is a need to characterize and analyze composite sandwich structural damage due to burning and explosion. Better understanding of the flammability and blast resistance of the composite structures

  10. Application of Composite Structures in Bridge Engineering. Problems of Construction Process and Strength Analysis

    Science.gov (United States)

    Flaga, Kazimierz; Furtak, Kazimierz

    2015-03-01

    Steel-concrete composite structures have been used in bridge engineering from decades. This is due to rational utilisation of the strength properties of the two materials. At the same time, the reinforced concrete (or prestressed) deck slab is more favourable than the orthotropic steel plate used in steel bridges (higher mass, better vibration damping, longer life). The most commonly found in practice are composite girder bridges, particularly in highway bridges of small and medium spans, but the spans may reach over 200 m. In larger spans steel truss girders are applied. Bridge composite structures are also employed in cable-stayed bridge decks of the main girder spans of the order of 600, 800 m. The aim of the article is to present the cionstruction process and strength analysis problems concerning of this type of structures. Much attention is paid to the design and calculation of the shear connectors characteristic for the discussed objects. The authors focused mainly on the issues of single composite structures. The effect of assembly states on the stresses and strains in composite members are highlighted. A separate part of problems is devoted to the influence of rheological factors, i.e. concrete shrinkage and creep, as well as thermal factors on the stresses and strains and redistribution of internal forces.

  11. Low-Cost Composite Materials and Structures for Aircraft Applications

    Science.gov (United States)

    Deo, Ravi B.; Starnes, James H., Jr.; Holzwarth, Richard C.

    2003-01-01

    A survey of current applications of composite materials and structures in military, transport and General Aviation aircraft is presented to assess the maturity of composites technology, and the payoffs realized. The results of the survey show that performance requirements and the potential to reduce life cycle costs for military aircraft and direct operating costs for transport aircraft are the main reasons for the selection of composite materials for current aircraft applications. Initial acquisition costs of composite airframe components are affected by high material costs and complex certification tests which appear to discourage the widespread use of composite materials for aircraft applications. Material suppliers have performed very well to date in developing resin matrix and fiber systems for improved mechanical, durability and damage tolerance performance. The next challenge for material suppliers is to reduce material costs and to develop materials that are suitable for simplified and inexpensive manufacturing processes. The focus of airframe manufacturers should be on the development of structural designs that reduce assembly costs by the use of large-scale integration of airframe components with unitized structures and manufacturing processes that minimize excessive manual labor.

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

    CERN Document Server

    Kostopoulos, V

    2013-01-01

    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...

  13. Structural investigation of composite wind turbine blade considering various load cases and fatigue life

    International Nuclear Information System (INIS)

    Kong, C.; Bang, J.; Sugiyama, Y.

    2005-01-01

    This study proposes a structural design for developing a medium scale composite wind turbine blade made of E-glass/epoxy for a 750 kW class horizontal axis wind turbine system. The design loads were determined from various load cases specified at the IEC61400-1 international specification and GL regulations for the wind energy conversion system. A specific composite structure configuration, which can effectively endure various loads such as aerodynamic loads and loads due to accumulation of ice, hygro-thermal and mechanical loads, was proposed. To evaluate the proposed composite wind turbine blade, structural analysis was performed by using the finite element method. Parametric studies were carried out to determine an acceptable blade structural design, and the most dominant design parameters were confirmed. In this study, the proposed blade structure was confirmed to be safe and stable under various load conditions, including the extreme load conditions. Moreover, the blade adapted a new blade root joint with insert bolts, and its safety was verified at design loads including fatigue loads. The fatigue life of a blade that has to endure for more than 20 years was estimated by using the well-known S-N linear damage theory, the service load spectrum, and the Spera's empirical equations. With the results obtained from all the structural design and analysis, prototype composite blades were manufactured. A specific construction process including the lay-up molding method was applied to manufacturing blades. Full-scale static structural test was performed with the simulated aerodynamic loads. From the experimental results, it was found that the designed blade had structural integrity. In addition, the measured results of deflections, strains, mass, and radial center of gravity agreed well with the analytical results. The prototype blade was successfully certified by an international certification institute, GL (Germanisher Lloyd) in Germany

  14. Young modulus and internal friction of a fiber-reinforced composite

    International Nuclear Information System (INIS)

    Ledbetter, H.M.; Lei, M.; Austin, M.W.

    1986-01-01

    By a kilohertz-frequency resonance method we determined the Young modulus and internal friction of a uniaxially fiber-reinforced composite. The composite comprised glass fibers in an epoxy-resin matrix. We studied three fiber contents: 0, 41, and 49 vol %. The Young modulus fit a linear rule of mixture. The internal friction fit a classical free-damped-oscillator model where one assumes a linear rule of mixture for three quantities: mass, force constant, and mechanical-resistance constant

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-08-28

    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.

  16. Structure and content of competitive group compositions in sports aerobics

    Directory of Open Access Journals (Sweden)

    Tetiana Moshenska

    2017-02-01

    Full Text Available Purpose: to make the analysis of modern competitive group compositions in sports aerobics. Material & Methods: pedagogical, sociological and methods of mathematical statistics were used. 10 coaches took part in the experimental part; analysis of protocols and video records of competitions of the aged category of children of 9–11 years old, who perform in the nomination of triplets and quintuples (group exercises, is carried out. Results: the content of competitive compositions and the allocated indicators are studied which defined it. Conclusions: the basic structural elements, which characterize competitive compositions, are allocated. Their components, quantity and time of performance are defined. It is established that variety of aerobic contents, spaces, and means of registration, musical compliance and logicality of creation of the whole competitive composition at high quality of performance characterizes teams – winners.

  17. Application of the self-diagnosis composite into concrete structure

    Science.gov (United States)

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

    2001-04-01

    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.

  18. Ceramic matrix composites -- Advanced high-temperature structural materials

    International Nuclear Information System (INIS)

    Lowden, R.A.; Ferber, M.K.; DiPietro, S.G.

    1995-01-01

    This symposium on Ceramic Matrix Composites: Advanced High-Temperature Structural Materials was held at the 1994 MRS Fall Meeting in Boston, Massachusetts on November 28--December 2. The symposium was sponsored by the Department of Energy's Office of Industrial Technology's Continuous Fiber Ceramic Composites Program, the Air Force Office of Scientific Research, and NASA Lewis Research Center. Among the competing materials for advanced, high-temperature applications, ceramic matrix composites are leading candidates. The symposium was organized such that papers concerning constituents--fibers and matrices--were presented first, followed by composite processing, modeling of mechanical behavior, and thermomechanical testing. More stable reinforcements are necessary to enhance the performance and life of fiber-reinforced ceramic composites, and to ensure final acceptance of these materials for high-temperature applications. Encouraging results in the areas of polymer-derived SiC fibers and single crystal oxide filaments were given, suggesting composites with improved thermomechanical properties and stability will be realized in the near future. The significance of the fiber-matrix interface in the design and performance of these materials is evident. Numerous mechanical models to relate interface properties to composite behavior, and interpret test methods and data, were enthusiastically discussed. One issue of great concern for any advanced material for use in extreme environments is stability. This theme arose frequently throughout the symposium and was the topic of focus on the final day. Fifty nine papers have been processed separately for inclusion on the data base

  19. A critical review of nanotechnologies for composite aerospace structures

    Science.gov (United States)

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

    2017-03-01

    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.

  20. Structural characterization and lipid composition of acquired cholesteatoma

    DEFF Research Database (Denmark)

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

    2012-01-01

    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...... 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...

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

    Directory of Open Access Journals (Sweden)

    B. Novotný

    2000-01-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Drago Skrtic

    2009-11-01

    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

  3. International society of sports nutrition position stand: diets and body composition

    OpenAIRE

    Aragon, Alan A.; Schoenfeld, Brad J.; Wildman, Robert; Kleiner, Susan; VanDusseldorp, Trisha; Taylor, Lem; Earnest, Conrad P.; Arciero, Paul J.; Wilborn, Colin; Kalman, Douglas S.; Stout, Jeffrey R.; Willoughby, Darryn S.; Campbell, Bill; Arent, Shawn M.; Bannock, Laurent

    2017-01-01

    Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on a critical analysis of the literature regarding the effects of diet types (macronutrient composition; eating styles) and their influence on body composition. The ISSN has concluded the following. 1) There is a multitude of diet types and eating styles, whereby numerous subtypes fall under each major dietary archetype. 2) All body composition assessment methods have strengths and limi...

  4. Variability in Parasites' Community Structure and Composition in Cat ...

    African Journals Online (AJOL)

    This study investigated the composition and structure of the parasite communities in Cat fish with respect to levels of water pollution in Lake Victoria. A total of 1071 Clarias gariepinus with mean TL range of 19 to 27 cm were analyzed from three localities in Mwanza Gulf (Kirumba, 298 fish infected with 15 parasite species), ...

  5. The influence of compositional and structural diversity on forest productivity

    Science.gov (United States)

    James N. Long; John D. Shaw

    2010-01-01

    Data from ~1500 ponderosa pine (Pinus ponderosa C. Lawson) stands in the western United States were used to examine the potential influence of compositional and structural diversity on forest productivity. Relative density, height and site quality were combined in a conceptually sound expression of the relationship between growth and growing stock for ponderosa pine-...

  6. Floristic Composition and Vegetation Structure of The KNUST ...

    African Journals Online (AJOL)

    The diversity, relative importance, canopy height and cover of plant species in the Kwame Nkrumah University of Science and Technology (KNUST) Botanic Garden were evaluated in five 1-ha plots using a stratified random sampling technique in order to build an understanding of its floristic composition and structure in two ...

  7. Resin transfer molding for advanced composite primary aircraft structures

    Science.gov (United States)

    Markus, Alan; Palmer, Ray

    1991-01-01

    Resin Transfer Molding (RTM) has been identified by Douglas Aircraft Company (DAC) and industry to be one of the promising processes being developed today which can break the cost barrier of implementing composite primary structures into a commercial aircraft production environment. The RTM process developments and scale-up plans Douglas Aircrart will be conducting under the NASA ACT contract are discussed.

  8. ALL NATURAL COMPOSITE SANDWICH BEAMS FOR STRUCTURAL APPLICATIONS. (R829576)

    Science.gov (United States)

    As part of developing an all natural composite roof for housing application,structural panels and unit beams were manufactured out of soybean oil based resinand natural fibers (flax, cellulose, pulp, recycled paper, chicken feathers)using vacuum assisted resin tran...

  9. Plant species composition and structure of the Mana Angetu moist ...

    African Journals Online (AJOL)

    A floristic composition and structure study of the Mana Angetu Forest was carried out between July 2003 and June 2004 at four sites of the forest with an altitudinal range of 1533-2431 m. Three transects, 750 ... Analysis of Importance Value Index indicated that Vepris dainellii had the highest value (79). The population ...

  10. Structural evolution of ZTA composites during synthesis and processing

    Czech Academy of Sciences Publication Activity Database

    Exare, C.; Kiat, J. M.; Guiblin, N.; Porcher, F.; Petříček, Václav

    2015-01-01

    Roč. 35, č. 4 (2015), s. 1273-1283 ISSN 0955-2219 R&D Projects: GA ČR(CZ) GA14-03276S Institutional support: RVO:68378271 Keywords : ceramic s * alumina–zirconia composites * structural properties * strain effect * size effect Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.933, year: 2015

  11. Innovative Structural Materials and Sections with Strain Hardening Cementitious Composites

    Science.gov (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

  12. Photoelastic Studies of Internal Stress Distributions of Unidirectional Composites.

    Science.gov (United States)

    1980-12-01

    34 verre a, If t nece, e.ry and Identify by block number) ..... ’Io-dimensional phutoelastli, models were used to determine internal taading-. and...Secretary of Defense for Research and Engineering, le Pe, ,tagon,, Uashington, D.C. 10301 ]2 Commandr, T)efens. lecn, ical Information Center, Cameron

  13. A Study of Flexible Composites for Expandable Space Structures

    Science.gov (United States)

    Scotti, Stephen J.

    2016-01-01

    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.

  14. Coplanar capacitance sensors for detecting water intrusion in composite structures

    International Nuclear Information System (INIS)

    Nassr, Amr A; El-Dakhakhni, Wael W; Ahmed, Wael H

    2008-01-01

    Composite materials are becoming more affordable and widely used for retrofitting, rehabilitating and repairing reinforced concrete structures designed and constructed under older specifications. However, the mechanical properties and long-term durability of composite materials may degrade severely in the presence of water intrusion. This study presents a new non-destructive evaluation (NDE) technique for detecting the water intrusion in composite structures by evaluating the dielectric properties of different composite system constituent materials. The variation in the dielectric signatures was employed to design a coplanar capacitance sensor with high sensitivity to detect such defects. An analytical model was used to study the effect of the sensor geometry on the output signal and to optimize sensor design. A finite element model was developed to validate analytical results and to evaluate other sensor design-related parameters. Experimental testing of a concrete specimen wrapped with composite laminate and containing a series of pre-induced water intrusion defects was conducted in order to validate the concept of the new technique. Experimental data showed excellent agreement with the finite element model predictions and confirmed sensor performance

  15. Natural Kenaf Fiber Reinforced Composites as Engineered Structural Materials

    Science.gov (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

  16. Health Monitoring of Composite Material Structures using a Vibrometry Technique

    Science.gov (United States)

    Schulz, Mark J.

    1997-01-01

    Large composite material structures such as aircraft and Reusable Launch Vehicles (RLVS) operate in severe environments comprised of vehicle dynamic loads, aerodynamic loads, engine vibration, foreign object impact, lightning strikes, corrosion, and moisture absorption. These structures are susceptible to damage such as delamination, fiber breaking/pullout, matrix cracking, and hygrothermal strain. To ensure human safety and load-bearing integrity, these structures must be inspected to detect and locate often invisible damage and faults before becoming catastrophic. Moreover, nearly all future structures will need some type of in-service inspection technique to increase their useful life and reduce maintenance and overall costs. Possible techniques for monitoring the health and indicating damage on composite structures include: c-scan, thermography, acoustic emissions using piezoceramic actuators or fiber-optic wires with gratings, laser ultrasound, shearography, holography, x-ray, and others. These techniques have limitations in detecting damage that is beneath the surface of the structure, far away from a sensor location, or during operation of the vehicle. The objective of this project is to develop a more global method for damage detection that is based on structural dynamics principles, and can inspect for damage when the structure is subjected to vibratory loads to expose faults that may not be evident by static inspection. A Transmittance Function Monitoring (TFM) method is being developed in this project for ground-based inspection and operational health monitoring of large composite structures as a RLV. A comparison of the features of existing health monitoring approaches and the proposed TFM method is given.

  17. Structural reasons for vertical integration in the international oil industry

    International Nuclear Information System (INIS)

    Luciani, G.

    1991-01-01

    Once upon a time, the international oil industry was vertically integrated. A small group of companies controlled a very substantial share of international oil flows, extending their operations from the oil well to the gas pump, and relying on intracorporate transfers for most in-between transactions. The historical reasons for vertical disintegration, the market role, and structural reasons for vertical reintegration are examined. (author)

  18. A structural model for composite rotor blades and lifting surfaces

    Science.gov (United States)

    Rehfield, Lawrence W.; Atilgan, Ali R.

    1987-01-01

    Composite material systems are currently candidates for aerospace structures, primarily for the design flexibiity they offer i.e., it is possible to tailor the material and manufacturing approach to the application. Two notable examples are the wing of the Grumman/USAF/DARPA X-29 and rotor blades under development by the U.S.A. Aerostructures Directorate (AVSCOM), Langley Research Center. A working definition of elastic or structural tailoring is the use of structural concept, fiber orientation, ply stacking sequence, and a blend of materials to achieve specific performance goals. In the design process, choices of materials and dimensions are made which produce specific response characteristics which permit the selected goals to be achieved. Common choices for tailoring goals are preventing instabilities or vibration resonances or enhancing damage tolerance. An essential, enabling factor in the design of tailored composite structures is structural modeling that accurately, but simply, characterizes response. The objective of this paper is to improve the single-cell beam model for composite rotor blades or lifting surfaces and to demonstrate its usefullness in applications.

  19. Superelastic SMA–FRP composite reinforcement for concrete structures

    International Nuclear Information System (INIS)

    Wierschem, Nicholas; Andrawes, Bassem

    2010-01-01

    For many years there has been interest in using fiber-reinforced polymers (FRPs) as reinforcement in concrete structures. Unfortunately, due to their linear elastic behavior, FRP reinforcing bars are never considered for structural damping or dynamic applications. With the aim of improving the ductility and damping capability of concrete structures reinforced with FRP reinforcement, this paper studies the application of SMA–FRP, a relatively novel type of composite reinforced with superelastic shape memory alloy (SMA) wires. The cyclic tensile behavior of SMA–FRP composites are studied experimentally and analytically. Tests of SMA–FRP composite coupons are conducted to determine their constitutive behavior. The experimental results are used to develop and calibrate a uniaxial SMA–FRP analytical model. Parametric and case studies are performed to determine the efficacy of the SMA–FRP reinforcement in concrete structures and the key factors governing its behavior. The results show significant potential for SMA–FRP reinforcement to improve the ductility and damping of concrete structures while still maintaining its elastic characteristic, typical of FRP reinforcement

  20. Hybrid Composites for LH2 Fuel Tank Structure

    Science.gov (United States)

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

    2001-01-01

    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.

  1. Progress In Developing an Impermeable, High Temperature Ceramic Composite for Advanced Reactor Clad And Structural Applications

    International Nuclear Information System (INIS)

    Feinroth, Herbert; Hao, Bernard; Fehrenbacher, Larry; Patterson, Mark

    2002-01-01

    Most Advanced Reactors for Energy and Space Applications require higher temperature materials for fuel cladding and core internal structures. For temperatures above 500 deg. C, metal alloys do not retain sufficient strength or long term corrosion resistance for use in either water, liquid metal or gas cooled systems. In the case of water cooled systems, such metals react exo-thermically with water during core overheating accidents, thus requiring extensive and expensive emergency systems to protect against major releases. Past efforts to apply ceramic composites (oxide, carbide or nitride based) having passive safety characteristics, good strength properties at high temperatures, and reasonable resistance to crack growth, have not been successful, either because of irradiation induced effects, or lack of impermeability to fission gases. Under a Phase 1 SBIR (Small Business Innovative Research) project sponsored by DOE's Office of Nuclear Energy, the authors have developed a new material system that may solve these problems. A hybrid tubular structure (0.6 inches in outside diameter) consisting of an inner layer of monolithic silicon carbide (SiC) and outer layers of SiC-SiC composite, bonded to the inner layer, has been fabricated in small lengths. Room temperature permeability tests demonstrate zero gas leakage at pressures up to 120 psig internal pressure. Four point flexural bending tests on these hybrid tubular specimens demonstrate a 'graceful' failure mode: i.e. - the outer composite structure sustains a failure mode under stress that is similar to the yield vs. stress characteristics of metal structures. (authors)

  2. Composition-structure-property relation of oxide glasses

    DEFF Research Database (Denmark)

    Hermansen, Christian

    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...... are proposed based on topological selection rules and experimentally verified. The relation between structure and properties is evaluated using topological constraint theory, which in its essence is a theory that quantifies the two intuitions of the glass scientist. The end result is a quantitative model...

  3. High temperature resin matrix composites for aerospace structures

    Science.gov (United States)

    Davis, J. G., Jr.

    1980-01-01

    Accomplishments and the outlook for graphite-polyimide composite structures are briefly outlined. Laminates, skin-stiffened and honeycomb sandwich panels, chopped fiber moldings, and structural components were fabricated with Celion/LARC-160 and Celion/PMR-15 composite materials. Interlaminar shear and flexure strength data obtained on as-fabricated specimens and specimens that were exposed for 125 hours at 589 K indicate that epoxy sized and polyimide sized Celion graphite fibers exhibit essentially the same behavior in a PMR-15 matrix composite. Analyses and tests of graphite-polyimide compression and shear panels indicate that utilization in moderately loaded applications offers the potential for achieving a 30 to 50 percent reduction in structural mass compared to conventional aluminum panels. Data on effects of moisture, temperature, thermal cycling, and shuttle fluids on mechanical properties indicate that both LARC-160 and PMR-15 are suitable matrix materials for a graphite-polyimide aft body flap. No technical road blocks to building a graphite-polyimide composite aft body flap are identified.

  4. 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: pushan@tifr.res.in [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005 (India)

    2016-02-14

    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.

  5. Optimization of SMA layers in composite structures to enhance damping

    Science.gov (United States)

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

    2016-04-01

    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.

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

    DEFF Research Database (Denmark)

    Du, Yan; Fan, Guohua; Yu, Tianbo

    2016-01-01

    Laminated Ti-Al composite sheets with different layer thickness ratios have been fabricated through hot pressing followed by multi-pass hot rolling at 500 °C.The laminated sheets show strong bonding with intermetallic interface layers of nanoscale thickness between the layers of Ti and Al....... 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...

  7. Rotational characterization of methyl methacrylate: Internal dynamics and structure determination

    Science.gov (United States)

    Herbers, Sven; Wachsmuth, Dennis; Obenchain, Daniel A.; Grabow, Jens-Uwe

    2018-01-01

    Rotational constants, Watson's S centrifugal distortion coefficients, and internal rotation parameters of the two most stable conformers of methyl methacrylate were retrieved from the microwave spectrum. Splittings of rotational energy levels were caused by two non equivalent methyl tops. Constraining the centrifugal distortion coefficients and internal rotation parameters to the values of the main isotopologues, the rotational constants of all single substituted 13C and 18O isotopologues were determined. From these rotational constants the substitution structures and semi-empirical zero point structures of both conformers were precisely determined.

  8. Structural and Infrastructural Underpinnings of International R&D Networks

    DEFF Research Database (Denmark)

    Niang, Mohamed; Sørensen, Brian Vejrum

    2009-01-01

    This paper explores the process of globally distributing R&D activities with an emphasis on the effects of network maturity. It discusses emerging configurations by asking how the structure and infrastructure of international R&D networks evolve along with the move from a strong R&D center...... to dispersed development. Drawing from case studies of two international R&D networks, it presents a capability maturity model and argues that understanding the interaction between new structures and infrastructures of the dispersed networks has become a key requirement for developing organizational...

  9. Fabricating Composite-Material Structures Containing SMA Ribbons

    Science.gov (United States)

    Turner, Travis L.; Cano, Roberto J.; Lach, Cynthia L.

    2003-01-01

    An improved method of designing and fabricating laminated composite-material (matrix/fiber) structures containing embedded shape-memory-alloy (SMA) actuators has been devised. Structures made by this method have repeatable, predictable properties, and fabrication processes can readily be automated. Such structures, denoted as shape-memory-alloy hybrid composite (SMAHC) structures, have been investigated for their potential to satisfy requirements to control the shapes or thermoelastic responses of themselves or of other structures into which they might be incorporated, or to control noise and vibrations. Much of the prior work on SMAHC structures has involved the use SMA wires embedded within matrices or within sleeves through parent structures. The disadvantages of using SMA wires as the embedded actuators include (1) complexity of fabrication procedures because of the relatively large numbers of actuators usually needed; (2) sensitivity to actuator/ matrix interface flaws because voids can be of significant size, relative to wires; (3) relatively high rates of breakage of actuators during curing of matrix materials because of sensitivity to stress concentrations at mechanical restraints; and (4) difficulty of achieving desirable overall volume fractions of SMA wires when trying to optimize the integration of the wires by placing them in selected layers only.

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

    DEFF Research Database (Denmark)

    Luczak, Marcin; Peeters, Bart; Kahsin, Maciej

    2014-01-01

    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......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...

  11. Stability analysis of internally damped rotating composite shafts using a finite element formulation

    Science.gov (United States)

    Ben Arab, Safa; Rodrigues, José Dias; Bouaziz, Slim; Haddar, Mohamed

    2018-04-01

    This paper deals with the stability analysis of internally damped rotating composite shafts. An Euler-Bernoulli shaft finite element formulation based on Equivalent Single Layer Theory (ESLT), including the hysteretic internal damping of composite material and transverse shear effects, is introduced and then used to evaluate the influence of various parameters: stacking sequences, fiber orientations and bearing properties on natural frequencies, critical speeds, and instability thresholds. The obtained results are compared with those available in the literature using different theories. The agreement in the obtained results show that the developed Euler-Bernoulli finite element based on ESLT including hysteretic internal damping and shear transverse effects can be effectively used for the stability analysis of internally damped rotating composite shafts. Furthermore, the results revealed that rotor stability is sensitive to the laminate parameters and to the properties of the bearings.

  12. Global assemblages and structural models of International Relations

    DEFF Research Database (Denmark)

    Corry, Olaf

    2014-01-01

    -category of assemblages – those constructed as malleable and governable which I call ‘governance-objects’ – is central to structure in international relations. The chapter begins with standard definitions of what structures are – patterns of interaction between elements – and briefly covers the range of models currently...... used to simplify different structures. Next the chapter points to the blindness of most structural theories of IR to the role of assemblages in general and governance-objects in particular. Thirdly, the idea that a polity is constituted precisely by the assemblage of a governance...

  13. Computational simulation of acoustic fatigue for hot composite structures

    Science.gov (United States)

    Singhal, S. N.; Nagpal, V. K.; Murthy, P. L. N.; Chamis, C. C.

    1991-01-01

    This paper presents predictive methods/codes for computational simulation of acoustic fatigue resistance of hot composite structures subjected to acoustic excitation emanating from an adjacent vibrating component. Select codes developed over the past two decades at the NASA Lewis Research Center are used. The codes include computation of (1) acoustic noise generated from a vibrating component, (2) degradation in material properties of the composite laminate at use temperature, (3) dynamic response of acoustically excited hot multilayered composite structure, (4) degradation in the first-ply strength of the excited structure due to acoustic loading, and (5) acoustic fatigue resistance of the excited structure, including propulsion environment. Effects of the laminate lay-up and environment on the acoustic fatigue life are evaluated. The results show that, by keeping the angled plies on the outer surface of the laminate, a substantial increase in the acoustic fatigue life is obtained. The effect of environment (temperature and moisure) is to relieve the residual stresses leading to an increase in the acoustic fatigue life of the excited panel.

  14. Concurrent Probabilistic Simulation of High Temperature Composite Structural Response

    Science.gov (United States)

    Abdi, Frank

    1996-01-01

    A computational structural/material analysis and design tool which would meet industry's future demand for expedience and reduced cost is presented. This unique software 'GENOA' is dedicated to parallel and high speed analysis to perform probabilistic evaluation of high temperature composite response of aerospace systems. The development is based on detailed integration and modification of diverse fields of specialized analysis techniques and mathematical models to combine their latest innovative capabilities into a commercially viable software package. The technique is specifically designed to exploit the availability of processors to perform computationally intense probabilistic analysis assessing uncertainties in structural reliability analysis and composite micromechanics. The primary objectives which were achieved in performing the development were: (1) Utilization of the power of parallel processing and static/dynamic load balancing optimization to make the complex simulation of structure, material and processing of high temperature composite affordable; (2) Computational integration and synchronization of probabilistic mathematics, structural/material mechanics and parallel computing; (3) Implementation of an innovative multi-level domain decomposition technique to identify the inherent parallelism, and increasing convergence rates through high- and low-level processor assignment; (4) Creating the framework for Portable Paralleled architecture for the machine independent Multi Instruction Multi Data, (MIMD), Single Instruction Multi Data (SIMD), hybrid and distributed workstation type of computers; and (5) Market evaluation. The results of Phase-2 effort provides a good basis for continuation and warrants Phase-3 government, and industry partnership.

  15. 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

    1997-12-01

    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.

  16. Damping analysis of cylindrical composite structures with enhanced viscoelastic properties

    DEFF Research Database (Denmark)

    Kliem, Mathias; Høgsberg, Jan Becker; Vanwalleghem, Joachim

    2018-01-01

    is forced to deform in shear mode. Thus, the vibration energy is dissipated as low grade frictional heat. This paper documents the efficiency of passive constrained layer damping treatments for low frequency vibrations of cylindrical composite specimens made of glass fibre-reinforced plastics. Different cross...... section geometries with shear webs have been investigated in order to study a beneficial effect on the damping characteristics of the cylinder. The viscoelastic damping layers are placed at different locations within the composite cylinder e.g. circumferential and along the neutral plane to evaluate...... in the neutral plane perpendicular to the bending load. The results are based on free decay tests of the composite structure....

  17. Ferrocement: A versatile composite structural material - A Review

    International Nuclear Information System (INIS)

    Memon, N. A.; Sumadi, S. R.

    2006-01-01

    The use of-based composites for structural application is becoming more popular with the introduction of new high performance materials. Ferrocement as a structural material has evolved from an appropriate technology applied for rural development to high performance and high durability construction material. The efficient use of ferrocement technology as per the requirements of the structures must be studied and developed in order to assist all the concerned parties concerned with structural activities. This paper is aimed to present the research made continuously to improve the ferrocement properties and performance and its uses in the different application and to encourage practical application of ferrocement especially in developing countries like Pakistan. This paper covers the theoretical, experimental and numerical studies conducted by several researchers to investigate the mechanical and structural properties of ferrocement. Also the efforts made to develop the design code offerrocement have been reviewed. (author)

  18. Polyurethane structural adhesives applied in automotive composite joints

    Directory of Open Access Journals (Sweden)

    Josue Garcia Quini

    2012-06-01

    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.

  19. Damage Evaluation and Analysis of Composite Pressure Vessels Using Fiber Bragg Gratings to Determine Structural Health

    National Research Council Canada - National Science Library

    Kunzler, Marley; Udd, Eric; Kreger, Stephen; Johnson, Mont; Henrie, Vaughn

    2005-01-01

    .... Using fiber Bragg gratings embedded into the weave structure of carbon fiber epoxy composites allow the capability to monitor these composites during manufacture, cure, general aging, and damage...

  20. Advanced Ceramic Matrix Composites with Multifunctional and Hybrid Structures

    Science.gov (United States)

    Singh, Mrityunjay; Morscher, Gregory N.

    2004-01-01

    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.

  1. Polycaprolactone/starch composite: Fabrication, structure, properties, and applications.

    Science.gov (United States)

    Ali Akbari Ghavimi, Soheila; Ebrahimzadeh, Mohammad H; Solati-Hashjin, Mehran; Abu Osman, Noor Azuan

    2015-07-01

    Interests in the use of biodegradable polymers as biomaterials have grown. Among the different polymeric composites currently available, the blend of starch and polycaprolactone (PCL) has received the most attention since the 1980s. Novamont is the first company that manufactured a PCL/starch (SPCL) composite under the trademark Mater-Bi®. The properties of PCL (a synthetic, hydrophobic, flexible, expensive polymer with a low degradation rate) and starch (a natural, hydrophilic, stiff, abundant polymer with a high degradation rate) blends are interesting because of the composite components have completely different structures and characteristics. PCL can adjust humidity sensitivity of starch as a biomaterial; while starch can enhance the low biodegradation rate of PCL. Thus, by appropriate blending, SPCL can overcome important limitations of both PCL and starch components and promote controllable behavior in terms of mechanical properties and degradation which make it suitable for many biomedical applications. This article reviewed the different fabrication and modification methods of the SPCL composite; different properties such as structural, physical, and chemical as well as degradation behavior; and different applications as biomaterials. © 2014 Wiley Periodicals, Inc.

  2. Multifunctional Composites for Future Energy Storage in Aerospace Structures

    Directory of Open Access Journals (Sweden)

    Till Julian Adam

    2018-02-01

    Full Text Available Multifunctionalization of fiber-reinforced composites, especially by adding energy storage capabilities, is a promising approach to realize lightweight structural energy storages for future transport vehicles. Compared to conventional energy storage systems, energy density can be increased by reducing parasitic masses of non-energy-storing components and by benefitting from the composite meso- and microarchitectures. In this paper, the most relevant existing approaches towards multifunctional energy storages are reviewed and subdivided into five groups by distinguishing their degree of integration and their scale of multifunctionalization. By introducing a modified range equation for battery-powered electric aircrafts, possible range extensions enabled by multifunctionalization are estimated. Furthermore, general and aerospace specific potentials of multifunctional energy storages are discussed. Representing an intermediate degree of structural integration, experimental results for a multifunctional energy-storing glass fiber-reinforced composite based on the ceramic electrolyte Li1.4Al0.4Ti1.6(PO43 are presented. Cyclic voltammetry tests are used to characterize the double-layer behavior combined with galvanostatic charge–discharge measurements for capacitance calculation. The capacitance is observed to be unchanged after 1500 charge–discharge cycles revealing a promising potential for future applications. Furthermore, the mechanical properties are assessed by means of four-point bending and tensile tests. Additionally, the influence of mechanical loads on the electrical properties is also investigated, demonstrating the storage stability of the composites.

  3. COMPUTER MODELING OF STRUCTURAL - CONCENTRATION CHARACTERISTICS OF BUILDING COMPOSITE MATERIALS

    Directory of Open Access Journals (Sweden)

    I. I. Zaripova

    2015-09-01

    Full Text Available In the article the computer modeling of structural and concentration characteristics of the building composite material on the basis of the theory of the package. The main provisions of the algorithmon the basis of which it was possible to get the package with a significant number of packaged elements, making it more representative in comparison with existing analogues modeling. We describe the modeled area related areas, the presence of which determines the possibility of a percolation process, which in turn makes it possible to study and management of individual properties of the composite material of construction. As an example of the construction of a composite material is considered concrete that does not exclude the possibility of using algorithms and modeling results of similar studies for composite matrix type (matrix of the same material and distributed in a certain way by volume particles of another substance. Based on modeling results can be manufactured parts and construction elementsfor various purposes with improved technical characteristics (by controlling the concentration composition substance.

  4. Oxidation resistance coating for niobium base structural composites

    International Nuclear Information System (INIS)

    Tabaru, T.; Shobu, K.; Kim, J.H.; Hirai, H.; Hanada, S.

    2003-01-01

    Oxidation behavior of Al-rich Mo(Si,Al) 2 base alloys, which is a candidate material for the oxidation resistance coating on Nb base structural composites, were investigated by thermogravimetry. The Mo(Si,Al) 2 base alloys containing Mo 5 (Si,Al) 3 up to about 10 vol% exhibits excellent oxidation resistance at temperatures ranging from 780 to 1580 K, particularly at 1580 K due to continuous Al 2 O 3 layer development. To evaluate the applicability of the Mo(Si,Al) 2 base coating, plasma spraying on Nb base composites were undertaken. However, interface reaction layer was found to form during the following heat treatment. Preparation of Mo(Si,Al) 2 /Al 2 O 3 /Nb layered structures via powder metallurgical process was attempted to preclude diffusion reaction between coating and substrate. (orig.)

  5. Advanced composites structural concepts and materials technologies for primary aircraft structures: Structural response and failure analysis

    Science.gov (United States)

    Dorris, William J.; Hairr, John W.; Huang, Jui-Tien; Ingram, J. Edward; Shah, Bharat M.

    1992-01-01

    Non-linear analysis methods were adapted and incorporated in a finite element based DIAL code. These methods are necessary to evaluate the global response of a stiffened structure under combined in-plane and out-of-plane loading. These methods include the Arc Length method and target point analysis procedure. A new interface material model was implemented that can model elastic-plastic behavior of the bond adhesive. Direct application of this method is in skin/stiffener interface failure assessment. Addition of the AML (angle minus longitudinal or load) failure procedure and Hasin's failure criteria provides added capability in the failure predictions. Interactive Stiffened Panel Analysis modules were developed as interactive pre-and post-processors. Each module provides the means of performing self-initiated finite elements based analysis of primary structures such as a flat or curved stiffened panel; a corrugated flat sandwich panel; and a curved geodesic fuselage panel. This module brings finite element analysis into the design of composite structures without the requirement for the user to know much about the techniques and procedures needed to actually perform a finite element analysis from scratch. An interactive finite element code was developed to predict bolted joint strength considering material and geometrical non-linearity. The developed method conducts an ultimate strength failure analysis using a set of material degradation models.

  6. Nanomembrane structures having mixed crystalline orientations and compositions

    Science.gov (United States)

    Lagally, Max G.; Scott, Shelley A.; Savage, Donald E.

    2014-08-12

    The present nanomembrane structures include a multilayer film comprising a single-crystalline layer of semiconductor material disposed between two other single-crystalline layers of semiconductor material. A plurality of holes extending through the nanomembrane are at least partially, and preferably entirely, filled with a filler material which is also a semiconductor, but which differs from the nanomembrane semiconductor materials in composition, crystal orientation, or both.

  7. Structural studies on an internal loop from a hairpin ribozyme

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Z.; SantaLucia, J. Jr.; Tinoco, I. Jr. [Univ. of California, Berkeley, CA (United States)

    1994-12-01

    Ribozymes, RNA enzymes, catalyze site-specific RNA cleavage and ligation reactions. We are studying the three-dimensional structure of a hairpin ribozyme derived from the minus strand of tobacco ring spot virus satellite RNA ((-)sTRSV), which has been engineering to specifically cleave the HIV-1 RNA. The minimum structure for the catalytic reaction involves a 50-nucleotide ribozyme and a 14-nucleotide substrate. The proposed secondary structure of the ribozyme-substrate complex consists of four short helices separated by two internal loops. The relatively large size (64-nucleotide) of the ribozyme-substrate complex presents formidable problems in solving the structure using NMR. Therefore we are studying smaller structural subunits of the complex. We are determining the high resolution structure of the symmetric internal loop involving the cleavage site and the flanking helices. One strand of the internal loop was selectively {sup 13}C-labeled at C8 of each purine and C6 of each pyrimidine. By using {sup 13}C-edited two-dimensional NMR, the proton NOESY spectrum was greatly simplified. This allowed unambiguous sequential proton resonance assignments along each strand. Three-dimensional {sup 1}-{sup 13}C HMQC-NOESY was used to further facilitate resonance assignments. We are also enzymatically synthesizing the entire 50-nucleotide ribozyme and will combine it with the {sup 13}C-labeled substrate. Through comparison of the NOE connectivities of the labeled nucleotides from the internal loop alone with those from the entire complex, the differences between the two structures can be elucidated.

  8. Structural health monitoring in composite materials using frequency response methods

    Science.gov (United States)

    Kessler, Seth S.; Spearing, S. Mark; Atalla, Mauro J.; Cesnik, Carlos E. S.; Soutis, Constantinos

    2001-08-01

    Cost effective and reliable damage detection is critical for the utilization of composite materials in structural applications. Non-destructive evaluation techniques (e.g. ultrasound, radiography, infra-red imaging) are available for use during standard repair and maintenance cycles, however by comparison to the techniques used for metals these are relatively expensive and time consuming. This paper presents part of an experimental and analytical survey of candidate methods for the detection of damage in composite materials. The experimental results are presented for the application of modal analysis techniques applied to rectangular laminated graphite/epoxy specimens containing representative damage modes, including delamination, transverse ply cracks and through-holes. Changes in natural frequencies and modes were then found using a scanning laser vibrometer, and 2-D finite element models were created for comparison with the experimental results. The models accurately predicted the response of the specimems at low frequencies, but the local excitation and coalescence of higher frequency modes make mode-dependent damage detection difficult and most likely impractical for structural applications. The frequency response method was found to be reliable for detecting even small amounts of damage in a simple composite structure, however the potentially important information about damage type, size, location and orientation were lost using this method since several combinations of these variables can yield identical response signatures.

  9. Modal identification of composite structures using Eigen realization method

    International Nuclear Information System (INIS)

    Hamidzadeh, H.R.; Afolabi, D.

    1996-01-01

    Experimental modal analysis has proved to be a useful tool to determine the vibration response of complex composite structures. An accurate method for extracting modal parameters of these type of structures are presented. The method used experimental impulse response of the system as input and provides natural frequencies and damping ratios of a dynamic system. The employed theories are Eigen Realization and Impulse Response methods. The adopted method is superior to other available methods in time and frequency domains. The presented method is proven to provide robustness with respect to measured noise

  10. The Candida albicans Biofilm Matrix: Composition, Structure and Function.

    Science.gov (United States)

    Pierce, Christopher G; Vila, Taissa; Romo, Jesus A; Montelongo-Jauregui, Daniel; Wall, Gina; Ramasubramanian, Anand; Lopez-Ribot, Jose L

    2017-03-01

    A majority of infections caused by Candida albicans -the most frequent fungal pathogen-are associated with biofilm formation. A salient feature of C. albicans biofilms is the presence of the biofilm matrix. This matrix is composed of exopolymeric materials secreted by sessile cells within the biofilm, in which all classes of macromolecules are represented, and provides protection against environmental challenges. In this review, we summarize the knowledge accumulated during the last two decades on the composition, structure, and function of the C. albicans biofilm matrix. Knowledge of the matrix components, its structure, and function will help pave the way to novel strategies to combat C. albicans biofilm infections.

  11. Airborne sound insulation of new composite wall structures

    Directory of Open Access Journals (Sweden)

    Ivanova Yonka

    2018-01-01

    Full Text Available Protection against noise is one of the essential requirements of the European Construction Product directive. In buildings, airborne sound insulation is used to define the acoustical quality between rooms. In order to develop wall structures with optimal sound insulation, an understanding of the physical origins of sound transmission is necessary. To develop a kind of knowledge that is applicable to the improvement of real walls and room barriers is the motive behind this study. The purpose of the work is to study the sound insulation of new composite wall structure.

  12. Nonlinear damage detection in composite structures using bispectral analysis

    Science.gov (United States)

    Ciampa, Francesco; Pickering, Simon; Scarselli, Gennaro; Meo, Michele

    2014-03-01

    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.

  13. Implementing optical fibres for the structural health monitoring of composite patch repaired structures

    DEFF Research Database (Denmark)

    Karatzas, Vasileios; Kotsidis, Elias A.; Tsouvalis, Nicholas G.

    2017-01-01

    Structural health monitoring is increasingly being implemented to improve the level of safety of structures and to reduce inspection and repair costs by allowing for correct planning of these actions, if needed. Composite patch repairing presents an appealing alternative to traditional repair...... methods as it enables the reduction of closedown time and the mitigation of complications associated with traditional repair methods. As reinforcement with the use of composite patches is predominantly performed at defected structures, the urge to monitor the performance of the repair becomes even greater...

  14. Elastic stability of biaxially loaded longitudinally stiffened composite structures.

    Science.gov (United States)

    Viswanathan, A. V.; Tamekuni, M.; Tripp, L. L.

    1973-01-01

    A linear analysis method is presented for the elastic stability of structures of uniform cross section, that may be idealized as an assemblage of laminated plate-strips, flat and curved, and beams. Each plate-strip and beam covers the entire length of the structure and is simply supported on the edges normal to the longitudinal axis. Arbitrary boundary conditions may be specified on any external longitudinal side of plate-strips. The structure or selected plate-strips may be loaded in any desired combination of inplane biaxial loads. The analysis simultaneously considers all modes of instability and is applicable for the buckling of laminated composite structures. Some numerical results are presented to indicate possible applications.

  15. Experimental study on beam for composite CES structural system

    Science.gov (United States)

    Matsui, Tomoya

    2017-10-01

    Development study on Concrete Encase Steel (CES) composite structure system has been continuously conducted toward the practical use. CES structure is composed of steel and fiber reinforced concrete. In previous study, it was found that CES structure has good seismic performance from experimental study of columns, beam - column joints, shear walls and a two story two span frame. However, as fundamental study on CES beam could be lacking, it is necessary to understand the structural performance of CES beam. In this study, static loading tests of CES beams were conducted with experimental valuable of steel size, the presence or absence of slab and thickness of slab. And restoring characteristics, failure behavior, deformation behavior, and strength evaluation method of CES beam were investigated. As the results, it was found that CES beam showed stable hysteresis behavior. Furthermore it was found that the flexural strength of the CES beam could be evaluated by superposition strength theory.

  16. Zirconia-hydroxyapatite composite material with micro porous structure.

    Science.gov (United States)

    Matsumoto, Takuya Junior; An, Sang-Hyun; Ishimoto, Takuya; Nakano, Takayoshi; Matsumoto, Takuya; Imazato, Satoshi

    2011-11-01

    Titanium plates and apatite blocks are commonly used for restoring large osseous defects in dental and orthopedic surgery. However, several cases of allergies against titanium have been recently reported. Also, sintered apatite block does not possess sufficient mechanical strength. In this study, we attempted to fabricate a composite material that has mechanical properties similar to biocortical bone and high bioaffinity by compounding hydroxyapatite (HAp) with the base material zirconia (ZrO(2)), which possesses high mechanical properties and low toxicity toward living organisms. After mixing the raw material powders at several different ZrO(2)/HAp mixing ratios, the material was compressed in a metal mold (8 mm in diameter) at 5 MPa. Subsequently, it was sintered for 5 h at 1500°C to obtain the ZrO(2)/HAp composite. The mechanical property and biocompatibility of materials were investigated. Furthermore, osteoconductivity of materials was investigated by animal studies. A composite material with a minute porous structure was successfully created using ZrO(2)/HAp powders, having different particle sizes, as the starting material. The material also showed high protein adsorption and a favorable cellular affinity. When the mixing ratio was ZrO(2)/HAp=70/30, the strength was equal to cortical bone. Furthermore, in vivo experiments confirmed its high osteoconductivity. The composite material had strength similar to biocortical bones with high cell and tissue affinities by compounding ZrO(2) and HAp. The ZrO(2)/HAp composite material having micro porous structure would be a promising bone restorative material. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Interface and internal compatibility in a copper fibre cement composite

    Directory of Open Access Journals (Sweden)

    Kittl, P.

    1993-09-01

    Full Text Available This paper presents the mechanical behaviour of a compacted composite formed by short ductile copper fibres randomly distributed in portland cement matrix. The samples, a half with fibres and the other without them, were subjected to compression fatigue. So, 1 hertz and the value of stress corresponding to the 1% of the probability of fracture by gradual load were used. Diagrams of cumulative probability of fracture against cycles are obtained for both types of samples. Scanning electron microscopy shows that the mechanisms of fracture are different in each case. Samples of compacted neat-cement paste finish their life with a catastrophic fracture whereas samples of composite behave like a pseudoductile material devoid of catastrophic failure. The results are discussed and compared with the ones obtained by thermal shock and by the interface brittleness theory, as well as with the statistical theory of time-dependent fracture for cementitious materials subjected to cyclic loading. So, in the thermal shock microcracks are generated in the interface matrix-fibre which simultaneously act as emmitings and sumps of cracks whereas this does not occur in mechanical fatigue.

    Este trabajo presenta el comportamiento mecánico de un compuesto fabricado por compactación y constituido por fibras de cobre distribuidas aleatoriamente en una matriz de cemento portland. Las muestras, la mitad con fibras y la otra sin ellas, se sometieron a fatiga por compresión. El ciclo de carga fue de 1 hertz y la carga aplicada aquella correspondiente a la tensión asociada a un 1% de probabilidad de fractura cuando la carga se aplica gradualmente. Para ambos tipos de muestras se graficaron los diagramas de probabilidad acumulativa de fractura en función del número de ciclos. Con microscopía electrónica de barrido se observó que el mecanismo de fractura es diferente para cada tipo de muestras. Aquellas de pasta pura de cemento compactada terminaron su ciclo de

  18. Fuel containment, lightning protection and damage tolerance in large composite primary aircraft structures

    Science.gov (United States)

    Griffin, Charles F.; James, Arthur M.

    1985-01-01

    The damage-tolerance characteristics of high strain-to-failure graphite fibers and toughened resins were evaluated. Test results show that conventional fuel tank sealing techniques are applicable to composite structures. Techniques were developed to prevent fuel leaks due to low-energy impact damage. For wing panels subjected to swept stroke lightning strikes, a surface protection of graphite/aluminum wire fabric and a fastener treatment proved effective in eliminating internal sparking and reducing structural damage. The technology features developed were incorporated and demonstrated in a test panel designed to meet the strength, stiffness, and damage tolerance requirements of a large commercial transport aircraft. The panel test results exceeded design requirements for all test conditions. Wing surfaces constructed with composites offer large weight savings if design allowable strains for compression can be increased from current levels.

  19. Structural design significance of tension-tension fatigue data on composites

    Science.gov (United States)

    Grimes, G. C.

    1977-01-01

    Constant cycle tension-tension fatigue and related static tension data have been generated on six single composite material/orientation combinations and twenty-one hybrid composite material/orientation combinations. Anomalies are related to the temperature rise and stopped interval creep, whereas endurance limit stresses (runouts) are associated with static proportional limit values, when they occur, and internal damage. The significance of these room temperature-dry data on the design allowables and weight of aerodynamic structueres is discussed. Such structures are helicopter rotor blades and wing and horizontal stabilizer lower surfaces. Typical criteria for turning these data into preliminary allowables are shown, as are examples of such allowables developed from the data. These values are then compared to those that might be used if the structures were made of metal.

  20. Sapphire/TiAl composites - structure and properties

    International Nuclear Information System (INIS)

    Povarova, K.B.; Antonova, A.V.; Mileiko, S.T.; Sarkissyan, N.S.

    2001-01-01

    Ti-Al-intermetallic-based alloys with lamellar microstructure, -γ(TiAl) +α 2 (Ti 3 Al) are characterized by a high melting point of 1460 o C, a low density of ∼3.9 g/cm 3 , a high gas corrosion resistance up to a temperature of about 900 o C, a high creep resistance up to a temperature of about 800 o C, and a sufficiently high fracture toughness at low temperatures, up to 30 Mpa x m 1/2 . Hence, they are considered as excellent matrices for fibres of high melting point. Unlike well-developed SiC/TiAl composites, which have an obvious upper limit for the usage temperature due to SiC/TiAl interaction, Sapphire/TiAl composites remain nearly unknown because fibres to be used in such composites have not been really available. At the present time, such fibres are developed in Solid State Physics Inst. of RAS. The results of preliminary creep tests of Al 2 O 3 /TiAl composites obtained by using pressure casting have shown that usage of such composite systems shifts the temperature limit for light structural materials in terms of creep resistance to, at least, 1050 o C: creep strength on 100 h time base reaches 120 MPa at that temperature. It occurs also that Sapphire-fibres/TiAl-matrix composite specimens have an increased gas corrosion resistance by more than one order of the magnitudes as compared with that of the matrix alloy. (author)

  1. Poling of PVDF matrix composites for integrated structural load sensing

    Science.gov (United States)

    Haghiashtiani, Ghazaleh; Greminger, Michael A.; Zhao, Ping

    2014-03-01

    The purpose of this study is to create and evaluate a smart composite structure that can be used for integrated load sensing and structural health monitoring. In this structure, PVDF films are used as the matrix material instead of epoxy resin or other thermoplastics. The reinforcements are two layers of carbon fiber with one layer of Kevlar separating them. Due to the electrical conductivity properties of carbon fiber and the dielectric effect of Kevlar, the structure acts as a capacitor. Furthermore, the piezoelectric properties of the PVDF matrix can be used to monitor the response of the structure under applied loads. In order to exploit the piezoelectric properties of PVDF, the PVDF material must be polarized to align the dipole moments of its crystalline structure. The optimal condition for poling the structure was found by performing a 23 factorial design of experiment (DoE). The factors that were studied in DoE were temperature, voltage, and duration of poling. Finally, the response of the poled structure was monitored by exposing the samples to an applied load.

  2. PEG-PE/clay composite carriers for doxorubicin: Effect of composite structure on release, cell interaction and cytotoxicity.

    Science.gov (United States)

    Kohay, Hagay; Sarisozen, Can; Sawant, Rupa; Jhaveri, Aditi; Torchilin, Vladimir P; Mishael, Yael G

    2017-06-01

    A novel drug delivery system for doxorubicin (DOX), based on organic-inorganic composites was developed. DOX was incorporated in micelles (M-DOX) of polyethylene glycol-phosphatidylethanolamine (PEG-PE) which in turn were adsorbed by the clay, montmorillonite (MMT). The nano-structures of the PEG-PE/MMT composites of LOW and HIGH polymer loadings were characterized by XRD, TGA, FTIR, size (DLS) and zeta measurements. These measurements suggest that for the LOW composite a single layer of polymer intercalates in the clay platelets and the polymer only partially covers the external surface, while for the HIGH composite two layers of polymer intercalate and a bilayer may form on the external surface. These nanostructures have a direct effect on formulation stability and on the rate of DOX release. The release rate was reversely correlated with the degree of DOX interaction with the clay and followed the sequence: M-DOX>HIGH formulation>LOW formulation>DOX/MMT. Despite the slower release from the HIGH formulation, its cytotoxicity effect on sensitive cells was as high as the "free" DOX. Surprisingly, the LOW formulation, with the slowest release, demonstrated the highest cytotoxicity in the case of Adriamycin (ADR) resistant cells. Confocal microscopy images and association tests provided an insight into the contribution of formulation-cell interactions vs. the contribution of DOX release rate. Internalization of the formulations was suggested as a mechanism that increases DOX efficiency, particularly in the ADR resistant cell line. The employment of organic-inorganic hybrid materials as drug delivery systems, has not reached its full potential, however, its functionality as an efficient tunable release system was demonstrated. DOX PEG-PE/clay formulations were design as an efficient drug delivery system. The main aim was to develop PEG-PE/clay formulations of different structures based on various PEG-PE/clay ratios in order to achieve tunable release rates, to control

  3. MOTIVATION INTERNALIZATION AND SIMPLEX STRUCTURE IN SELF-DETERMINATION THEORY.

    Science.gov (United States)

    Ünlü, Ali; Dettweiler, Ulrich

    2015-12-01

    Self-determination theory, as proposed by Deci and Ryan, postulated different types of motivation regulation. As to the introjected and identified regulation of extrinsic motivation, their internalizations were described as "somewhat external" and "somewhat internal" and remained undetermined in the theory. This paper introduces a constrained regression analysis that allows these vaguely expressed motivations to be estimated in an "optimal" manner, in any given empirical context. The approach was even generalized and applied for simplex structure analysis in self-determination theory. The technique was exemplified with an empirical study comparing science teaching in a classical school class versus an expeditionary outdoor program. Based on a sample of 84 German pupils (43 girls, 41 boys, 10 to 12 years old), data were collected using the German version of the Academic Self-Regulation Questionnaire. The science-teaching format was seen to not influence the pupils' internalization of identified regulation. The internalization of introjected regulation differed and shifted more toward the external pole in the outdoor teaching format. The quantification approach supported the simplex structure of self-determination theory, whereas correlations may disconfirm the simplex structure.

  4. Discrete Optimization of Internal Part Structure via SLM Unit Structure-Performance Database

    Directory of Open Access Journals (Sweden)

    Li Tang

    2018-01-01

    Full Text Available The structural optimization of the internal structure of parts based on three-dimensional (3D printing has been recognized as being important in the field of mechanical design. The purpose of this paper is to present a creation of a unit structure-performance database based on the selective laser melting (SLM, which contains various structural units with different functions and records their structure and performance characteristics so that we can optimize the internal structure of parts directly, according to the database. The method of creating the unit structure-performance database was introduced in this paper and several structural units of the unit structure-performance database were introduced. The bow structure unit was used to show how to create the structure-performance database of the unit as an example. Some samples of the bow structure unit were designed and manufactured by SLM. These samples were tested in the WDW-100 compression testing machine to obtain their performance characteristics. After this, the paper collected all data regarding unit structure parameters, weight, performance characteristics, and other data; and, established a complete set of data from the bow structure unit for the unit structure-performance database. Furthermore, an aircraft part was reconstructed conveniently to be more lightweight according to the unit structure-performance database. Its weight was reduced by 36.8% when compared with the original structure, while the strength far exceeded the requirements.

  5. Internal structure changes of eyelash induced by eye makeup.

    Science.gov (United States)

    Fukami, Ken-Ichi; Inoue, Takafumi; Kawai, Tomomitsu; Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio

    2014-01-01

    To investigate how eye makeup affects eyelash structure, internal structure of eyelashes were observed with a scanning X-ray microscopic tomography system using synchrotron radiation light source. Eyelash samples were obtained from 36 Japanese women aged 20-70 years and whose use of eye makeup differed. Reconstructed cross-sectional images showed that the structure of the eyelash closely resembled that of scalp hair. The eyelash structure is changed by use of eye makeup. There was a positive correlation between the frequency of mascara use and the degree of cracking in cuticle. The positive correlation was also found between the frequency of mascara use and the porosity of the cortex. By contrast, the use of eyelash curler did not affect the eyelash structure with statistical significance.

  6. Team locus-of-control composition, leadership structure, information acquisition, and financial performance: A business simulation study

    NARCIS (Netherlands)

    Boone, Christophe; Van Olffen, W; van Witteloostuijn, A

    2005-01-01

    We argue that team information acquisition mediates the effect of the relationship of team locus-of-control composition and leadership structure on team financial performance in a decision-making context. Hypotheses were tested on 44 teams participating in an elaborate and lengthy international

  7. Structural Behaviour of Strengthened Composite Materials. Experimental Studies

    Directory of Open Access Journals (Sweden)

    Vlad Munteanu

    2007-01-01

    Full Text Available Masonry represents one of the earliest structural materials used by mankind. A lot of the ancient building structures were made using masonry. A large number of these buildings have been stated historical monuments. Most commonly masonry elements which are able to cover large spans was masonry arches. The paper makes a detailed presentation on structural behaviour and failure mechanisms of a horizontally loaded masonry arch. The arch model was built at a 1 : 1 scale using solid bricks and M10Z mortar. It was firstly loaded with vertically acting dead loads and with horizontal load acting in its plane. In this loading hypothesis, a plastic hinge occurred leading to the failure of the arch and loss of load bearing capacity. In the next stage of the experimental program, the arch was strengthened using a composite material membrane at the upper face. The membrane consisted in a continuous, glass-fiber fabric and epoxy resin. After proper curing, the same loading hypothesis was used. The failure mechanisms changed and a larger horizontal loading level was noticed. Further on, the arch was rehabilitated using a different composite material layout, the membrane was applied both on upper and bottom faces as well as partially on the lateral faces of the arch. This new rehabilitation layout leads to a significant increase in the load bearing capacity of the arch. The failure mechanisms were changed causing a significantly better overall structural behaviour of the arch.

  8. Composition-Structure-Property Relations of Compressed Borosilicate Glasses

    Science.gov (United States)

    Svenson, Mouritz N.; Bechgaard, Tobias K.; Fuglsang, Søren D.; Pedersen, Rune H.; Tjell, Anders Ø.; Østergaard, Martin B.; Youngman, Randall E.; Mauro, John C.; Rzoska, Sylwester J.; Bockowski, Michal; Smedskjaer, Morten M.

    2014-08-01

    Hot isostatic compression is an interesting method for modifying the structure and properties of bulk inorganic glasses. However, the structural and topological origins of the pressure-induced changes in macroscopic properties are not yet well understood. In this study, we report on the pressure and composition dependences of density and micromechanical properties (hardness, crack resistance, and brittleness) of five soda-lime borosilicate glasses with constant modifier content, covering the extremes from Na-Ca borate to Na-Ca silicate end members. Compression experiments are performed at pressures ≤1.0 GPa at the glass transition temperature in order to allow processing of large samples with relevance for industrial applications. In line with previous reports, we find an increasing fraction of tetrahedral boron, density, and hardness but a decreasing crack resistance and brittleness upon isostatic compression. Interestingly, a strong linear correlation between plastic (irreversible) compressibility and initial trigonal boron content is demonstrated, as the trigonal boron units are the ones most disposed for structural and topological rearrangements upon network compaction. A linear correlation is also found between plastic compressibility and the relative change in hardness with pressure, which could indicate that the overall network densification is responsible for the increase in hardness. Finally, we find that the micromechanical properties exhibit significantly different composition dependences before and after pressurization. The findings have important implications for tailoring microscopic and macroscopic structures of glassy materials and thus their properties through the hot isostatic compression method.

  9. Neutron scattering analysis of rubber carbon black composite structure

    International Nuclear Information System (INIS)

    Hjelm, R.P. Jr.; Wampler, W.A.; Gerspacher, M.

    1994-01-01

    We explore the uses of small-angle neutron scattering to dissect component form, structure and distribution in carbon black-reinforced rubber by varying the contrast of the system relative to some fluid by changing the fluid scattering-length density. This is the method of contrast variation. Contrast variation allows us to separate scattering contributions from the different components. Here, we extend our studies on high surface area (HSA) carbon black suspended in cyclohexane/deuterocyclohexane to HSA mixed with polyisoprene as a gel of ''bound'' rubber swollen with the same solvent mixtures. Contrast variation of swollen composite gels shows that there are two length scales in the gel structure. Above 1 nm fluctuations in the carbon black predominate. Interactions with elastomer hold the HSA aggregates appart. Below 1 nm the scattering is largely from the elastomer. The smooth surface structure of the carbon black is unaltered by the interactions with elastomer and appears smooth over length scales above about 1 nm. These results show that contrast variation can provide information on composite structure that is not available by other means. This information relates to the reinforcement mechanism of elastomers by carbon blacks

  10. Integration of fluidic jet actuators in composite structures

    Science.gov (United States)

    Schueller, Martin; Lipowski, Mathias; Schirmer, Eckart; Walther, Marco; Otto, Thomas; Geßner, Thomas; Kroll, Lothar

    2015-04-01

    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.

  11. Constitutive modeling and control of 1D smart composite structures

    Science.gov (United States)

    Briggs, Jonathan P.; Ostrowski, James P.; Ponte-Castaneda, Pedro

    1998-07-01

    Homogenization techniques for determining effective properties of composite materials may provide advantages for control of stiffness and strain in systems using hysteretic smart actuators embedded in a soft matrix. In this paper, a homogenized model of a 1D composite structure comprised of shape memory alloys and a rubber-like matrix is presented. With proportional and proportional/integral feedback, using current as the input state and global strain as an error state, implementation scenarios include the use of tractions on the boundaries and a nonlinear constitutive law for the matrix. The result is a simple model which captures the nonlinear behavior of the smart composite material system and is amenable to experiments with various control paradigms. The success of this approach in the context of the 1D model suggests that the homogenization method may prove useful in investigating control of more general smart structures. Applications of such materials could include active rehabilitation aids, e.g. wrist braces, as well as swimming/undulating robots, or adaptive molds for manufacturing processes.

  12. Active structural health monitoring of composite plates and sandwiches

    Directory of Open Access Journals (Sweden)

    Sadílek P.

    2013-12-01

    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.

  13. COMPOSITIONAL AND SUBSTANTIAL STRUCTURE OF THE MEDICAL DOCUMENT: FORMATION STAGES

    Directory of Open Access Journals (Sweden)

    Romashova Olga Vladimirovna

    2015-03-01

    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.

  14. Thermal properties of composite materials with a complex fractal structure

    International Nuclear Information System (INIS)

    Cervantes-Álvarez, F; Reyes-Salgado, J J; Dossetti, V; Carrillo, J L

    2014-01-01

    In this work, we report the thermal characterization of platelike composite samples made of polyester resin and magnetite inclusions. By means of photoacoustic spectroscopy and thermal relaxation, the thermal diffusivity, conductivity and volumetric heat capacity of the samples were experimentally measured. The volume fraction of the inclusions was systematically varied in order to study the changes in the effective thermal conductivity of the composites. For some samples, a static magnetic field was applied during the polymerization process, resulting in anisotropic inclusion distributions. Our results show a decrease in the thermal conductivity of some of the anisotropic samples, compared to the isotropic randomly distributed ones. Our analysis indicates that the development of elongated inclusion structures leads to the formation of magnetite and resin domains, causing this effect. We correlate the complexity of the inclusion structure with the observed thermal response through a multifractal and lacunarity analysis. All the experimental data are contrasted with the well known Maxwell–Garnett effective media approximation for composite materials. (paper)

  15. Polymer sol-gel composite inverse opal structures.

    Science.gov (United States)

    Zhang, Xiaoran; Blanchard, G J

    2015-03-25

    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.

  16. Engineering method to build the composite structure ply database

    Directory of Open Access Journals (Sweden)

    Qinghua Shi

    Full Text Available In this paper, a new method to build a composite ply database with engineering design constraints is proposed. This method has two levels: the core stacking sequence design and the whole stacking sequence design. The core stacking sequences are obtained by the full permutation algorithm considering the ply ratio requirement and the dispersion character which characterizes the dispersion of ply angles. The whole stacking sequences are the combinations of the core stacking sequences. By excluding the ply sequences which do not meet the engineering requirements, the final ply database is obtained. One example with the constraints that the total layer number is 100 and the ply ratio is 30:60:10 is presented to validate the method. This method provides a new way to set up the ply database based on the engineering requirements without adopting intelligent optimization algorithms. Keywords: Composite ply database, VBA program, Structure design, Stacking sequence

  17. Local Structure Fixation in the Composite Manufacturing Chain

    Science.gov (United States)

    Girdauskaite, Lina; Krzywinski, Sybille; Rödel, Hartmut; Wildasin-Werner, Andrea; Böhme, Ralf; Jansen, Irene

    2010-12-01

    Compared to metal materials, textile reinforced composites show interesting features, but also higher production costs because of low automation rate in the manufacturing chain at this time. Their applicability is also limited due to quality problems, which restrict the production of complex shaped dry textile preforms. New technologies, design concepts, and cost-effective manufacturing methods are needed in order to establish further fields of application. This paper deals with possible ways to improve the textile deformation process by locally applying a fixative to the structure parallel to the cut. This hinders unwanted deformation in the textile stock during the subsequent stacking and formation steps. It is found that suitable thermoplastic binders, applied in the appropriate manner do not restrict formation of the textile and have no negative influence on the mechanical properties of the composite.

  18. Production and Structural Investigation of Polyethylene Composites with Modified Kaolin

    International Nuclear Information System (INIS)

    Domka, L.; Malicka, A.; Stachowiak, N.

    2008-01-01

    The study was undertaken to evaluate the effect of the filler (kaolin) modification with silane coupling agents on the properties of the polyethylene (HDPE Hostalen ACP 5831) composites. Powder mineral fillers are added to polymers to modify the properties of the latter and to reduce the cost of their production. A very important factor is the filler dispersion in the polymer matrix. Kaolin modified with 3-methacryloxypropyltrimethoxysilane and pure kaolin were characterised by surface area, pore size, water absorbing capacity, paraffin oil absorbing capacity, bulk density, scanning electron microscopy observations and X-ray diffraction measurements. Their performance was characterised by determination of the mechanical resistance upon static stretching and tearing, and their structure was observed in scanning electron microscopy images. The results were compared to those obtained for the composites with unmodified filler and pure HDPE. (authors)

  19. Production and Structural Investigation of Polyethylene Composites with Modified Kaolin

    Science.gov (United States)

    Domka, L.; Malicka, A.; Stachowiak, N.

    2008-08-01

    The study was undertaken to evaluate the effect of the filler (kaolin) modification with silane coupling agents on the properties of the polyethylene (HDPE Hostalen ACP 5831) composites. Powder mineral fillers are added to polymers to modify the properties of the latter and to reduce the cost of their production. A very important factor is the filler dispersion in the polymer matrix. Kaolin modified with 3-methacryloxypropyltrimethoxysilane and pure kaolin were characterised by surface area, pore size, water absorbing capacity, paraffin oil absorbing capacity, bulk density, scanning electron microscopy observations and X-ray diffraction measurements. Their performance was characterised by determination of the mechanical resistance upon static stretching and tearing, and their structure was observed in scanning electron microscopy images. The results were compared to those obtained for the composites with unmodified filler and pure HDPE.

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

    Science.gov (United States)

    Di Sante, Raffaella

    2015-01-01

    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. PMID:26263987

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

    Directory of Open Access Journals (Sweden)

    Raffaella Di Sante

    2015-07-01

    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.

  2. Structure of Al-CF composites obtained by infiltration methods

    Directory of Open Access Journals (Sweden)

    A. Dolata-Grosz

    2011-04-01

    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".

  3. Structural, spectral and dielectric properties of piezoelectric-piezomagnetic composites

    Energy Technology Data Exchange (ETDEWEB)

    Hemeda, O.M., E-mail: omhemeda@yahoo.co.uk [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)

    2012-10-15

    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.

  4. Structural, spectral and dielectric properties of piezoelectric–piezomagnetic composites

    International Nuclear Information System (INIS)

    Hemeda, O.M.; Tawfik, A.; Amer, M.A.; Kamal, B.M.; El Refaay, D.E.

    2012-01-01

    Composite materials of spinel ferrite (SF) NiZnFe 2 O 4 (NZF) and barium titanate (BT) BaTiO 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 δ) decreased by increasing BT content. - Highlights: ► Double phase NZF-BT composite has a high magnetoelectric coefficient compared with other materials. ► This makes it strongly candidates for electromagnetic wave sensors. ► Addition of BT phase enhance dielectric constant which make it very useful for capacitor industry. ► Ni ferrite shifts the transition temperature of BT from 120 °C near room temperature. ► Decrease of dielectric loss which supply with good material with law eddy current loss for cores of t ransformers at microwave frequency.

  5. The internal structure of magnetic nanoparticles determines the magnetic response

    Czech Academy of Sciences Publication Activity Database

    Pacáková, Barbara; Kubíčková, Simona; Salas, G.; Mantlíková, Alice; Marciello, M.; Morales, M.P.; Nižňanský, D.; Vejpravová, Jana

    2017-01-01

    Roč. 9, č. 16 (2017), s. 5129-5140 ISSN 2040-3364 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:68378271 Keywords : nanoparticles * single-domain * internal structure Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 7.367, year: 2016

  6. The effect of internal magnetic structure on the fishbone instability

    International Nuclear Information System (INIS)

    Roberts, D.W.; Powell, E.; Kaita, R.; Bell, R.; Chance, M.; Hatcher, R.; Holland, A.; Kaye, S.; Kessel, C.; Kugel, H.; LeBlanc, B.; Manickam, J.; Okabayashi, M.; Paul, S.; Pomphrey, N.; Sauthoff, N.; Sesnic, S.; Takahashi, H.; White, R.; Asakura, N.; Duperrex, P.; Gammel, G.

    1992-01-01

    Plasmas exhibiting the ''fishbone'' instability studied on the PBX-M tokamak show a distinct relationship between the plasma shape, the internal magnetic structure, and the presence or absence of fast ion losses associated with the fishbone mode. We have, for the first time, carried out measurements of the magnetic safety factor profile in fishbone-unstable plasmas, and used the knowledge of the associated experimental equilibria to compare the stability and fast ion loss properties of these plasmas with experimental observations

  7. Study of damping characteristics of fibre reinforced composite aerospace structure

    International Nuclear Information System (INIS)

    Khan, M.Z.; Saleh, S.; Munir, A.

    2006-01-01

    Composite materials are used in a variety of high demanding structural applications. Apart from their other preferable properties, they have high-energy dissipation characteristics, which is important aspect when we repeatedly wiggle the system back and forth. It is important to have thorough understanding of material damping behavior; in general materials damping tends to be complex nonlinear function of vibration amplitude, frequency of loading and material formulation. There are number of mathematical models available in literature to obtain hysteresis curves. One approach for identifying damping characteristics used mechanical hysteresis curves. In present work, a phenomenon was observed during testing of fibre reinforced composite beam of an aerospace structure, that for increase load in structure, the path of Force vs. Displacement curve is different than the path of unloading. A plot is generated which indicate the hysteresis loop representing the steady state dynamic behavior of material. The area enclosed by such curves is proportional to energy dissipation per cycle. However, the specific shape of the curve also has important implications for characterizing the specific functional form of the damping. Therefore, it is important to develop methods for accurately accounting for such effects. The current work explores the damping characteristics both theoretically and experimentally. (author)

  8. CARBONIZED STARCH MICROCELLULAR FOAM-CELLULOSE FIBER COMPOSITE STRUCTURES

    Directory of Open Access Journals (Sweden)

    Andrew R. Rutledge

    2008-11-01

    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.

  9. Energy density and rate limitations in structural composite supercapacitors

    Science.gov (United States)

    Snyder, J. F.; Gienger, E.; Wetzel, E. D.; Xu, K.

    2012-06-01

    The weight and volume of conventional energy storage technologies greatly limits their performance in mobile platforms. Traditional research efforts target improvements in energy density to reduce device size and mass. Enabling a device to perform additional functions, such as bearing mechanical load, is an alternative approach as long as the total mass efficiency exceeds that of the individual materials it replaces. Our research focuses on structural composites that function as batteries and supercapacitors. These multifunctional devices could be used to replace conventional structural components, such as vehicle frame elements, to provide significant system-level weight reductions and extend mission times. Our approach is to design structural properties directly into the electrolyte and electrode materials. Solid polymer electrolyte materials bind the system and transfer load to the fibers while conducting ions between the electrodes. Carbon fiber electrodes provide a route towards optimizing both energy storage and load-bearing capabilities, and may also obviate the need for a separate current collector. The components are being integrated using scalable, cost-effective composite processing techniques that are amenable to complex part shapes. Practical considerations of energy density and rate behavior are described here as they relate to materials used. Our results highlight the viability as well as the challenges of this multifunctional approach towards energy storage.

  10. Proceedings of the Third International Workshop on Jointed Structures.

    Energy Technology Data Exchange (ETDEWEB)

    Starr, Michael James; Brake, Matthew Robert; Segalman, Daniel Joseph; Bergman, Lawrence A.; Ewins, David J.

    2013-08-01

    The Third International Workshop on Jointed Structures was held from August 16th to 17th, 2012, in Chicago Illinois, following the ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. Thirty two researchers from both the United States and international locations convened to discuss the recent progress of mechanical joints related research and associated efforts in addition to developing a roadmap for the challenges to be addressed over the next five to ten years. These proceedings from the workshop include the minutes of the discussions and follow up from the 2009 workshop [1], presentations, and outcomes of the workshop. Specifically, twelve challenges were formulated from the discussions at the workshop, which focus on developing a better understanding of uncertainty and variability in jointed structures, incorporating high fidelity models of joints in simulations that are tractable/efficient, motivating a new generation of researchers and funding agents as to the importance of joint mechanics research, and developing new insights into the physical phenomena that give rise to energy dissipation in jointed structures. The ultimate goal of these research efforts is to develop a predictive model of joint mechanics.

  11. Structural and functional polymer-matrix composites for electromagnetic applications

    Science.gov (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 O.cm, 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

  12. Advanced composite structural concepts and material technologies for primary aircraft structures

    Science.gov (United States)

    Jackson, Anthony

    1991-01-01

    Structural weight savings using advanced composites have been demonstrated for many years. Most military aircraft today use these materials extensively and Europe has taken the lead in their use in commercial aircraft primary structures. A major inhibiter to the use of advanced composites in the United States is cost. Material costs are high and will remain high relative to aluminum. The key therefore lies in the significant reduction in fabrication and assembly costs. The largest cost in most structures today is assembly. As part of the NASA Advanced Composite Technology Program, Lockheed Aeronautical Systems Company has a contract to explore and develop advanced structural and manufacturing concepts using advanced composites for transport aircraft. Wing and fuselage concepts and related trade studies are discussed. These concepts are intended to lower cost and weight through the use of innovative material forms, processes, structural configurations and minimization of parts. The approach to the trade studies and the downselect to the primary wing and fuselage concepts is detailed. The expectations for the development of these concepts is reviewed.

  13. Influence of chemical structure on carbon isotope composition of lignite

    Science.gov (United States)

    Erdenetsogt, Bat-Orshikh; Lee, Insung; Ko, Yoon-Joo; Mungunchimeg, Batsaikhan

    2017-04-01

    During the last two decades, a number of studies on carbon isotopes in terrestrial organic matter (OM) have been carried out and used to determine changes in paleoatmospheric δ13C value as well as assisting in paleoclimate analysis. Coal is abundant terrestrial OM. However, application of its δ13C value is very limited, because the understanding of changes in isotopic composition during coalification is relatively insufficient. The purpose of this study was to examine the influence of the chemical structure on the carbon isotope composition of lignite. Generally, lignite has more complex chemical structures than other higher rank coal because of the existence of various types of oxygen-containing functional groups that are eliminated at higher rank level. A total of sixteen Lower Cretaceous lignite samples from Baganuur mine (Mongolia) were studied by ultimate, stable carbon isotope and solid-state 13C CP/MAS NMR analyses. The carbon contents of the samples increase with increase in depth, whereas oxygen content decreases continuously. This is undoubtedly due to normal coalification process and also consistent with solid state NMR results. The δ13C values of the samples range from -23.54‰ to -21.34‰ and are enriched in 13C towards the lowermost samples. Based on the deconvolution of the NMR spectra, the ratios between carbons bonded to oxygen (60-90 ppm and 135-220 ppm) over carbons bonded to carbon and hydrogen (0-50 ppm and 90-135 ppm) were calculated for the samples. These correlate well with δ13C values (R2 0.88). The results indicate that the δ13C values of lignite are controlled by two mechanisms: (i) depletion in 13C as a result of loss of isotopically heavy oxygen-bounded carbons and (ii) enrichment in 13C caused by a loss of isotopically light methane from aliphatic and aromatic carbons. At the rank of lignite, coal is enriched in 13C because the amount of isotopically heavy CO2 and CO, released from coal as a result of changes in the chemical

  14. Metal matrix composite fabrication processes for high performance aerospace structures

    Science.gov (United States)

    Ponzi, C.

    A survey is conducted of extant methods of metal matrix composite (MMC) production in order to serve as a basis for prospective MMC users' selection of a matrix/reinforcement combination, cost-effective primary fabrication methods, and secondary fabrication techniques for the achievement of desired performance levels. Attention is given to the illustrative cases of structural fittings, control-surface connecting rods, hypersonic aircraft air inlet ramps, helicopter swash plates, and turbine rotor disks. Methods for technical and cost analysis modeling useful in process optimization are noted.

  15. The effect of neutron irradiation on the structure and properties of carbon-carbon composite materials

    International Nuclear Information System (INIS)

    Burchell, T.D.; Eatherly, W.P.; Robbins, J.M.; Strizak, J.P.

    1991-01-01

    Carbon-based materials are an attractive choice for fusion reactor plasma facing components (PFCs) because of their low atomic number, superior thermal shock resistance, and low neutron activation. Next generation plasma fusion reactors, such as the International Thermonuclear Experimental Reactor (ITER), will require advanced carbon-carbon composite materials possessing extremely high thermal conductivity to manage the anticipated severe heat loads. Moreover, ignition machines such as ITER will produce high neutron fluxes. Consequently, the influence of neutron damage on the structure and properties of carbon-carbon composite materials must be evaluated. Data from an irradiation experiment are reported and discussed here. Fusion relevant graphite and carbon-carbon composites were irradiated in a target capsule in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). A peak damage dose of 1.59 dpa at 600 degrees C was attained. The carbon materials irradiated included nuclear graphite grade H-451 and one-, two-, and three-directional carbon-carbon composite materials. Dimensional changes, thermal conductivity and strength are reported for the materials examined. The influence of fiber type, architecture, and heat treatment temperature on properties and irradiation behavior are reported. Carbon-Carbon composite dimensional changes are interpreted in terms of simple microstructural models

  16. Structural Composite Supercapacitors: Electrical and Mechanical Impact of Separators and Processing Conditions

    Science.gov (United States)

    2013-09-01

    Structural Composite Supercapacitors : Electrical and Mechanical Impact of Separators and Processing Conditions by Edwin B. Gienger, James F...Proving Ground, MD 21005-5066 ARL-TR-6624 September 2013 Structural Composite Supercapacitors : Electrical and Mechanical Impact of...2012 4. TITLE AND SUBTITLE Structural Composite Supercapacitors : Electrical and Mechanical Impact of Separators and Processing Conditions 5a

  17. Challenges and Opportunities for Nanotechnology in Multi-Functional Composite Structures (Preprint)

    National Research Council Canada - National Science Library

    Baur, Jeff; Silverman, Edward

    2006-01-01

    .... Of the wide variety of structural applications, fiber-reinforced composites for aerospace structures have some of the most demanding applications with extreme requirements in physical, chemical...

  18. Effects of heat treatment on optical absorption properties of Ni-P/AAO nano-array composite structure

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi-Fan; Wang, Feng-Hua; Guo, Dong-Lai; Huang, Sheng-You; Zou, Xian-Wu [Wuhan University, Department of Physics, Wuhan (China); Sang, Jian-Ping [Wuhan University, Department of Physics, Wuhan (China); Jianghan University, Department of Physics, Wuhan (China)

    2009-11-15

    Ni-P/AAO nano-array composite structure assemblies with Ni and P grown in the pores of anodic aluminum oxide (AAO) membranes were prepared by electroless deposition. The results of SEM, TEM and SAED show that as-deposited Ni-P nanowires have an amorphous structure and a few nanocrystallites form after annealing. The optical absorption spectra reveal that, as the annealing temperature increases, the absorption band edge of the Ni-P/AAO composite structure is obviously blue shifted, which is attributed to a decrease of the internal pressure after heat treatment. Meanwhile, the annealed Ni-P/AAO nano-array composite structure exhibits the absorption behavior of a direct band gap semiconductor. Details of this behavior are discussed together with the implications for potential device applications. (orig.)

  19. FORMATION REGULARITIES OF PHASE COMPOSITION, STRUCTURE AND PROPERTIES DURING MECHANICAL ALLOYING OF BINARY ALUMINUM COMPOSITES

    Directory of Open Access Journals (Sweden)

    F. G. Lovshenko

    2015-01-01

    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.

  20. 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

    2015-01-05

    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.

  1. Design, fabrication and structural optimization of tubular carbon/Kevlar®/PMMA/graphene nanoplate composite for bone fixation prosthesis.

    Science.gov (United States)

    Nasiri, F; Ajeli, S; Semnani, D; Jahanshahi, M; Emadi, R

    2018-05-02

    The present work investigates the mechanical properties of tubular carbon/Kevlar ® composite coated with poly(methyl methacrylate)/graphene nanoplates as used in the internal fixation of bones. Carbon fibers are good candidates for developing high-strength biomaterials and due to better stress transfer and electrical properties, they can enhance tissue formation. In order to improve carbon brittleness, ductile Kevlar ® was added to the composite. The tubular carbon/Kevlar ® composites have been prepared with tailorable braiding technology by changing the fiber pattern and angle in the composite structure and the number of composite layers. Fuzzy analyses are used for optimizing the tailorable parameters of 80 prepared samples and then mechanical properties of selected samples are discussed from the viewpoint of mechanical properties required for a bone fixation device. Experimental results showed that with optimizing braiding parameters the desired composite structure with mechanical properties close to bone properties could be produced. Results showed that carbon/Kevlar ® braid's physical properties, fiber composite distribution and diameter uniformity resulted in matrix uniformity, which enhanced strength and modulus due to better ability for distributing stress on the composite. Finally, as graphene nanoplates demonstrated their potential properties to improve wound healing intended for bone replacement, so reinforcing the PMMA matrix with graphene nanoplates enhanced the composite quality, for use as an implant.

  2. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    Directory of Open Access Journals (Sweden)

    Ying Luo

    Full Text Available The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  3. Effect of Yeast Cell Morphology, Cell Wall Physical Structure and Chemical Composition on Patulin Adsorption.

    Science.gov (United States)

    Luo, Ying; Wang, Jianguo; Liu, Bin; Wang, Zhouli; Yuan, Yahong; Yue, Tianli

    2015-01-01

    The capability of yeast to adsorb patulin in fruit juice can aid in substantially reducing the patulin toxic effect on human health. This study aimed to investigate the capability of yeast cell morphology and cell wall internal structure and composition to adsorb patulin. To compare different yeast cell morphologies, cell wall internal structure and composition, scanning electron microscope, transmission electron microscope and ion chromatography were used. The results indicated that patulin adsorption capability of yeast was influenced by cell surface areas, volume, and cell wall thickness, as well as 1,3-β-glucan content. Among these factors, cell wall thickness and 1,3-β-glucan content serve significant functions. The investigation revealed that patulin adsorption capability was mainly affected by the three-dimensional network structure of the cell wall composed of 1,3-β-glucan. Finally, patulin adsorption in commercial kiwi fruit juice was investigated, and the results indicated that yeast cells could adsorb patulin from commercial kiwi fruit juice efficiently. This study can potentially simulate in vitro cell walls to enhance patulin adsorption capability and successfully apply to fruit juice industry.

  4. [Volunteer satisfaction: Internal structure and relationship with permanence in organizations].

    Science.gov (United States)

    Vecina Jiménez, M L; Chacón Fuertes, Fernando; Sueiro Abad, Manuel J

    2009-02-01

    Volunteer satisfaction: Internal structure and relationship with permanence in organizations. The concept of satisfaction is considered theoretically relevant in practically all the studies that have investigated the factors that influence the permanence of volunteer participation in organizations. However, the practical results are not conclusive, perhaps due to the wide range of ways in which the concept is understood and measured. The object of this study is: to analyse the internal structure of satisfaction and to verify its relationship with volunteer duration in organizations. The results of the factor analysis yield a three-factor structure: Satisfaction with the management of the organization, Satisfaction with the tasks, Satisfaction of motivations. The three factors allow us to differentiate between individuals who remain in the organization for a period of 12 consecutive months, and those who leave earlier. The results of structural equation model analysis show that the relationship between satisfaction and the length of time that volunteers stay with the organization is affected by the intention to remain.

  5. Optimal Design of Composite Structures Under Manufacturing Constraints

    DEFF Research Database (Denmark)

    Marmaras, Konstantinos

    algorithms to perform the global optimization. The efficiency of the proposed models is examined on a set of well–defined discrete multi material and thickness optimization problems originating from the literature. The inclusion of manufacturing limitations along with structural considerations in the early...... 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...

  6. Active control of structures using macro-fiber composite (MFC)

    Energy Technology Data Exchange (ETDEWEB)

    Kovalovs, A; Barkanov, E; Gluhihs, S [Institute of Materials and Structures, Riga Technical University, 16/20 Azenes Str., Riga, LV-1048 (Latvia)

    2007-12-15

    This paper presents the use of macro-fiber composites (MFC) for vibration reduces of structures. The MFC consist of polyimid films with IDE-electrodes that are glued on the top and the bottom of rectangular piezoceramic fibers. The interdigitated electrodes deliver the electric field required to activate the piezoelectric effect in the fibers and allows to invoke the stronger longitudinal piezoelectric effect along the length of the fibers. When this actuator embedded in a surface or attached to flexible structures, the MFC actuator provides distributed solid-state deflection and vibration control. The major advantages of the piezoelectric fibre composite actuators are their high performance, flexibility, and durability when compared with the traditional piezoceramic (PZT) actuators. In addition, the ability of MFC devices to couple the electrical and mechanical fields is larger than in monolithic PZT. In this study, we showed the experimental results that an MFC could be used as actuator to find modal parameters and reduce vibration for structures such as an aluminium beam and metal music plate. Two MFC actuators were attached to the surfaces of test subjects. First MFC actuator used to supply a signal as exciter of vibration and second MFC show his application for reduction of vibration in the range of resonance frequencies. Experimental results of aluminium beam with MFC actuators compared with finite element model which modelled in ANSYS software. The applied voltage is modelled as a thermal load according to thermal analogy for MFC. The experimental and numerical results presented in this paper confirm the potential of MFC for use in the vibration control of structures.

  7. Bamboo–Polylactic Acid (PLA) Composite Material for Structural Applications

    Science.gov (United States)

    Pozo Morales, Angel; Güemes, Alfredo; Fernandez-Lopez, Antonio; Carcelen Valero, Veronica; De La Rosa Llano, Sonia

    2017-01-01

    Developing an eco-friendly industry based on green materials, sustainable technologies, and optimum processes with low environmental impact is a general societal goal, but this remains a considerable challenge to achieve. Despite the large number of research on green structural composites, limited investigation into the most appropriate manufacturing methodology to develop a structural material at industrial level has taken place. Laboratory panels have been manufactured with different natural fibers but the methodologies and values obtained could not be extrapolated at industrial level. Bamboo industry panels have increased in the secondary structural sector such as building application, flooring and sport device, because it is one of the cheapest raw materials. At industrial level, the panels are manufactured with only the inner and intermediate region of the bamboo culm. However, it has been found that the mechanical properties of the external shells of bamboo culm are much better than the average cross-sectional properties. Thin strips of bamboo (1.5 mm thick and 1500 mm long) were machined and arranged with the desired lay-up and shape to obtain laminates with specific properties better than those of conventional E-Glass/Epoxy laminates in terms of both strength and stiffness. The strips of bamboo were bonded together by a natural thermoplastic polylactic acid (PLA) matrix to meet biodegradability requirements. The innovative mechanical extraction process developed in this study can extract natural strip reinforcements with high performance, low cost, and high rate, with no negative environmental impact, as no chemical treatments are used. The process can be performed at the industrial level. Furthermore, in order to validate the structural applications of the composite, the mechanical properties were analyzed under ageing conditions. This material could satisfy the requirements for adequate mechanical properties and life cycle costs at industrial sectors such

  8. Bamboo-Polylactic Acid (PLA) Composite Material for Structural Applications.

    Science.gov (United States)

    Pozo Morales, Angel; Güemes, Alfredo; Fernandez-Lopez, Antonio; Carcelen Valero, Veronica; De La Rosa Llano, Sonia

    2017-11-09

    Developing an eco-friendly industry based on green materials, sustainable technologies, and optimum processes with low environmental impact is a general societal goal, but this remains a considerable challenge to achieve. Despite the large number of research on green structural composites, limited investigation into the most appropriate manufacturing methodology to develop a structural material at industrial level has taken place. Laboratory panels have been manufactured with different natural fibers but the methodologies and values obtained could not be extrapolated at industrial level. Bamboo industry panels have increased in the secondary structural sector such as building application, flooring and sport device, because it is one of the cheapest raw materials. At industrial level, the panels are manufactured with only the inner and intermediate region of the bamboo culm. However, it has been found that the mechanical properties of the external shells of bamboo culm are much better than the average cross-sectional properties. Thin strips of bamboo (1.5 mm thick and 1500 mm long) were machined and arranged with the desired lay-up and shape to obtain laminates with specific properties better than those of conventional E-Glass/Epoxy laminates in terms of both strength and stiffness. The strips of bamboo were bonded together by a natural thermoplastic polylactic acid (PLA) matrix to meet biodegradability requirements. The innovative mechanical extraction process developed in this study can extract natural strip reinforcements with high performance, low cost, and high rate, with no negative environmental impact, as no chemical treatments are used. The process can be performed at the industrial level. Furthermore, in order to validate the structural applications of the composite, the mechanical properties were analyzed under ageing conditions. This material could satisfy the requirements for adequate mechanical properties and life cycle costs at industrial sectors such

  9. Bamboo–Polylactic Acid (PLA Composite Material for Structural Applications

    Directory of Open Access Journals (Sweden)

    Angel Pozo Morales

    2017-11-01

    Full Text Available Developing an eco-friendly industry based on green materials, sustainable technologies, and optimum processes with low environmental impact is a general societal goal, but this remains a considerable challenge to achieve. Despite the large number of research on green structural composites, limited investigation into the most appropriate manufacturing methodology to develop a structural material at industrial level has taken place. Laboratory panels have been manufactured with different natural fibers but the methodologies and values obtained could not be extrapolated at industrial level. Bamboo industry panels have increased in the secondary structural sector such as building application, flooring and sport device, because it is one of the cheapest raw materials. At industrial level, the panels are manufactured with only the inner and intermediate region of the bamboo culm. However, it has been found that the mechanical properties of the external shells of bamboo culm are much better than the average cross-sectional properties. Thin strips of bamboo (1.5 mm thick and 1500 mm long were machined and arranged with the desired lay-up and shape to obtain laminates with specific properties better than those of conventional E-Glass/Epoxy laminates in terms of both strength and stiffness. The strips of bamboo were bonded together by a natural thermoplastic polylactic acid (PLA matrix to meet biodegradability requirements. The innovative mechanical extraction process developed in this study can extract natural strip reinforcements with high performance, low cost, and high rate, with no negative environmental impact, as no chemical treatments are used. The process can be performed at the industrial level. Furthermore, in order to validate the structural applications of the composite, the mechanical properties were analyzed under ageing conditions. This material could satisfy the requirements for adequate mechanical properties and life cycle costs at

  10. Active control of structures using macro-fiber composite (MFC)

    International Nuclear Information System (INIS)

    Kovalovs, A; Barkanov, E; Gluhihs, S

    2007-01-01

    This paper presents the use of macro-fiber composites (MFC) for vibration reduces of structures. The MFC consist of polyimid films with IDE-electrodes that are glued on the top and the bottom of rectangular piezoceramic fibers. The interdigitated electrodes deliver the electric field required to activate the piezoelectric effect in the fibers and allows to invoke the stronger longitudinal piezoelectric effect along the length of the fibers. When this actuator embedded in a surface or attached to flexible structures, the MFC actuator provides distributed solid-state deflection and vibration control. The major advantages of the piezoelectric fibre composite actuators are their high performance, flexibility, and durability when compared with the traditional piezoceramic (PZT) actuators. In addition, the ability of MFC devices to couple the electrical and mechanical fields is larger than in monolithic PZT. In this study, we showed the experimental results that an MFC could be used as actuator to find modal parameters and reduce vibration for structures such as an aluminium beam and metal music plate. Two MFC actuators were attached to the surfaces of test subjects. First MFC actuator used to supply a signal as exciter of vibration and second MFC show his application for reduction of vibration in the range of resonance frequencies. Experimental results of aluminium beam with MFC actuators compared with finite element model which modelled in ANSYS software. The applied voltage is modelled as a thermal load according to thermal analogy for MFC. The experimental and numerical results presented in this paper confirm the potential of MFC for use in the vibration control of structures

  11. Metal–organic coordinated multilayer film formation: Quantitative analysis of composition and structure

    Energy Technology Data Exchange (ETDEWEB)

    Benson, Alexandra S.; Elinski, Meagan B.; Ohnsorg, Monica L.; Beaudoin, Christopher K.; Alexander, Kyle A.; Peaslee, Graham F.; DeYoung, Paul A.; Anderson, Mary E., E-mail: meanderson@hope.edu

    2015-09-01

    Metal–organic coordinated multilayers are self-assembled thin films fabricated by alternating solution–phase deposition of bifunctional organic molecules and metal ions. The multilayer film composed of α,ω-mercaptoalkanoic acid and Cu (II) has been the focus of fundamental and applied research with its robust reproducibility and seemingly simple hierarchical architecture. However, internal structure and composition have not been unambiguously established. The composition of films up to thirty layers thick was investigated using Rutherford backscattering spectrometry and particle induced X-ray emission. Findings show these films are copper enriched, elucidating a 2:1 ratio for the ion to molecule complexation at the metal–organic interface. Results also reveal that these films have an average layer density similar to literature values established for a self-assembled monolayer, indicating a robust and stable structure. The surface structures of multilayer films have been characterized by contact angle goniometry, ellipsometry, and scanning probe microscopy. A morphological transition is observed as film thickness increases from the first few foundational layers to films containing five or more layers. Surface roughness analysis quantifies this evolution as the film initially increases in roughness before obtaining a lower roughness comparable to the underlying gold substrate. Quantitative analysis of topographical structure and internal composition for metal–organic coordinated multilayers as a function of number of deposited layers has implications for their incorporation in the fields of photonics and nanolithography. - Highlights: • Layer-by-layer deposition is examined by scanning probe microscopy and ion beam analysis. • Film growth undergoes morphological evolution during foundational layer deposition. • Image analysis quantified surface features such as roughness, grain size, and coverage. • Molecular density of each film layer is found to

  12. Integration of Composite Structures in Modern Day Architecture: Case Study of City Business Centre, Timisoara, Romania

    Science.gov (United States)

    Vataman, Adina; Gaivoronschi, Vlad; Mosoarca, Marius

    2017-10-01

    In current day structural design the use of composite steel-concrete structures has become the norm; because of the advantages that each of these materials has to offer. Composite structures also have the benefit of a faster execution at a lower cost, compared to traditional structures. While the arguments in favour of designing composite structures are well-known and appreciated by civil engineers; there remains a question of integrating these structures in modern-day urban landscapes. Eastern European countries are welcoming a blossoming of culture, arts, economy and industry, which unavoidably and necessarily will lead to a change in urban landscapes. With an increasing amount of foreign companies opening offices in these areas, the need for modern office solutions has arisen. The current paper presents a case study of an office building complex situated in the western part of Romania, in the city of Timişoara. The complex consists of 5 office buildings; all designed in composite steel-concrete structure, an underground parking lot, multiple terraces and adjacent promenade areas. Within the context of rapid growth and development of the city, the City Business Centre has offered high quality office spaces in the heart of the city, while considering the needs of the community. A very important aspect in the successful completion of the project was the efficient and professional collaboration between the separate project teams, between the owner, represented by the project management team, the architect, the structural designer and the building company. The successful joining of seismic structural solutions with modern architectural aesthetics has led to a dynamic, vibrant environment, making the City Business Centre the core of the region’s business life, at the same time redefining Timisoara’s architectural landscape. A testimony to the success of the project was the Civil Engineering Structural Designers Associations’ (AICPS) 3rd Prize awarded for great

  13. Structural policy in the context of international competition aggravation

    Directory of Open Access Journals (Sweden)

    Volodymyr Bodrov

    2014-09-01

    Full Text Available This article researches the essence and peculiarities of the structural policy, performs classification of its models and determines possibilities of their use in the context of increasing international competition. It discovers the main components of the economic structure and trends of the state policy regarding their modernization. Measures on improvement of state regulation instruments are offered, factors of influence upon improvement of the Ukrainian economy structure are analyzed and priority goals are systematized which require urgent implementation in the terms of competitive struggle aggravation at the global markets. The article also researches the matter of importance of performing a complex of state functional and selective measures in the form of matrix policy for the purpose of protecting national interests of the country in the context of global challenges

  14. Autonomous stimulus triggered self-healing in smart structural composites

    International Nuclear Information System (INIS)

    Norris, C J; White, J A P; McCombe, G; Chatterjee, P; Bond, I P; Trask, R S

    2012-01-01

    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. (paper)

  15. Role of contamination on the bondline integrity of composite structures

    Energy Technology Data Exchange (ETDEWEB)

    Shang, Xu [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    Adhesively bonding composite structures have many applications in aerospace, automotive and submarine industries. The adhesive bonding joints have substantial advantage over the traditional metallic mechanical bonding joints, such as rivet and welding. However, the adhesive bonding joints require additional steps of surface preparation and cleaning to ensure consistent bond strength. In application, the adhesively bonded joints are exposed to environmental degradation and industrial solvent contaminates. Accordingly, the assurance of reliability of bonded composite structures requires detailed investigation of the role of contaminates on bondline integrity. This dissertation focuses on assessing the contaminates effect on the adhesive bondline integrity. A combined experimental and numerical framework is developed to study the contamination effect on the adhesive mechanical properties and adhesive joint strength. The bondline integrity were examined for a system of adhesive (EA9394) and the carbonfiber system (Hexply IM7/8552), after being subjected to different level of exposures to aviation hydraulic fluids and mold cleaning agents. A testing protocol based on nanoindentation for initial screening is used to predict the interfacial fracture characteristics after exposure to contamination. It is found the adhesive modulus and stiffness dropped by up to 10% for the hydraulic fluid contaminates, suggesting increase of the plastic dissipation within the bondline. However, the trend for the cleaning agent was not clear since the modulus drop while its hardness increased.

  16. Connectivity and propagule sources composition drive ditch plant metacommunity structure

    Science.gov (United States)

    Favre-Bac, Lisa; Ernoult, Aude; Mony, Cendrine; Rantier, Yann; Nabucet, Jean; Burel, Françoise

    2014-11-01

    The fragmentation of agricultural landscapes has a major impact on biodiversity. In addition to habitat loss, dispersal limitation increasingly appears as a significant driver of biodiversity decline. Landscape linear elements, like ditches, may reduce the negative impacts of fragmentation by enhancing connectivity for many organisms, in addition to providing refuge habitats. To characterize these effects, we investigated the respective roles of propagule source composition and connectivity at the landscape scale on hydrochorous and non-hydrochorous ditch bank plant metacommunities. Twenty-seven square sites (0.5 km2 each) were selected in an agricultural lowland of northern France. At each site, plant communities were sampled on nine ditch banks (totaling 243 ditches). Variables characterizing propagule sources composition and connectivity were calculated for landscape mosaic and ditch network models. The landscape mosaic influenced only non-hydrochorous species, while the ditch network impacted both hydrochorous and non-hydrochorous species. Non-hydrochorous metacommunities were dependent on a large set of land-use elements, either within the landscape mosaic or adjacent to the ditch network, whereas hydrochorous plant metacommunities were only impacted by the presence of ditches adjacent to crops and roads. Ditch network connectivity also influenced both hydrochorous and non-hydrochorous ditch bank plant metacommunity structure, suggesting that beyond favoring hydrochory, ditches may also enhance plant dispersal by acting on other dispersal vectors. Increasing propagule sources heterogeneity and connectivity appeared to decrease within-metacommunity similarity within landscapes. Altogether, our results suggest that the ditch network's composition and configuration impacts plant metacommunity structure by affecting propagule dispersal possibilities, with contrasted consequences depending on species' dispersal vectors.

  17. Use of geonics scientific positions for designing of building composites for protective (fortification) structures

    Science.gov (United States)

    Fediuk, R. S.; Yevdokimova, Yu G.; Smoliakov, A. K.; Stoyushko, N. Yu; Lesovik, V. S.

    2017-07-01

    The examples of the implementation of the geological (geomimetic) positions in construction materials science are given in the work. The wall materials obtained with this technology have a much more developed surface than traditional wall materials. The second example of using such approaches is the development of internal care systems that will create a more highly organized structure of cement stone at the macro-, micro- and nano-scale levels and concrete in general at all stages: the stage of mixing, hardening and exploitation of the material. The regularities of the structure formation processes are revealed and the principles for increasing the efficiency of non-autoclaved aerated concrete due to application of composite binders, process control in a three-phase disperse porous system and the development of technological methods for the production of protective (fortification) structures are developed.

  18. Application of ceramic short fiber reinforced Al alloy matrix composite on piston for internal combustion engines

    Directory of Open Access Journals (Sweden)

    Wu Shenqing

    2010-11-01

    Full Text Available The preparation and properties of ceramic short fiber reinforced Al-Si alloy matrix composite and it’s application on the piston for internal combustion engines are presented. Alumina or aluminosilicate fibers reinforced Al-Si alloy matrix composite has more excellent synthetical properties at elevated temperature than the matrix alloys. A partially reinforced Al-Si alloy matrix composite piston produced by squeeze casting technique has a firm interface between reinforced and unreinforced areas, low reject rate and good technical tolerance. As a new kind of piston material, it has been used for mass production of about 400,000 pieces of automobile engines piston. China has become one of a few countries in which aluminum alloy matrix composite materials have been used in automobile industry and attained industrialization.

  19. Laminated structure in internally oxidized Ru-Ta coatings

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yung-I, E-mail: yichen@mail.ntou.edu.tw

    2012-12-01

    During the development of refractory alloy coatings for protective purposes at high temperature under oxygen-containing atmospheres, previous studies noted and examined the internal oxidation phenomenon for Mo-Ru and Ru-Ta coatings. The internally oxidized zone shows a laminated structure, consisting of alternating oxygen-rich and deficient layers stacked with a general orientation. Previous studies proposed a forming mechanism. To investigate in detail, Ru-Ta coatings were prepared with various rotating speeds of a substrate-holder. The coatings were annealed at 600 Degree-Sign C in an atmosphere continuously purged with 1% O{sub 2}-99% Ar mixed gas for 30 min. Transmission electron microscopy was used to examine the laminated-layer periods. Auger electron spectroscopy depth profiles certified the periodical variation of the related constituents. X-ray photoelectron spectroscopy proved the valence variation of Ta in the near surface, accompanied by the introduction of oxygen ions. The inward diffusion of oxygen was dominated by lattice diffusion. - Highlights: Black-Right-Pointing-Pointer Laminated Ru-Ta coatings consisted of a cyclical gradient concentration. Black-Right-Pointing-Pointer The as-deposited coatings showed a laminated structure with a period of 4-34 nm. Black-Right-Pointing-Pointer Internal oxidation of Ru-Ta coatings executed after annealing in 1% O{sub 2}-Ar atmosphere. Black-Right-Pointing-Pointer Oxygen inward diffusion was dominated by lattice diffusion.

  20. S09 Symposium KK, Structure-Property Relationships in Biomineralized and Biomimetic Composites

    Energy Technology Data Exchange (ETDEWEB)

    David Kisailus; Lara Estroff; Himadri S. Gupta; William J. Landis; Pablo D. Zavattieri

    2010-06-07

    The technical presentations and discussions at this symposium disseminated and assessed current research and defined future directions in biomaterials research, with a focus on structure-function relationships in biological and biomimetic composites. The invited and contributed talks covered a diverse range of topics from fundamental biology, physics, chemistry, and materials science to potential applications in developing areas such as light-weight composites, multifunctional and smart materials, biomedical engineering, and nanoscaled sensors. The invited speakers were chosen to create a stimulating program with a mixture of established and junior faculty, industrial and academic researchers, and American and international experts in the field. This symposium served as an excellent introduction to the area for younger scientists (graduate students and post-doctoral researchers). Direct interactions between participants also helped to promote potential future collaborations involving multiple disciplines and institutions.

  1. Composite structure of wood cells in petrified wood

    International Nuclear Information System (INIS)

    Nowak, Jakub; Florek, Marek; Kwiatek, Wojciech; Lekki, Janusz; Chevallier, Pierre; Zieba, Emil; Mestres, Narcis; Dutkiewicz, E.M.; Kuczumow, Andrzej

    2005-01-01

    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, μ-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 μ-Raman and μ-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

  2. 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)

    2005-04-28

    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.

  3. Validity of Chinese Version of the Composite International Diagnostic Interview-3.0 in Psychiatric Settings

    Institute of Scientific and Technical Information of China (English)

    Jin Lu; Yue-Qin Huang; Zhao-Rui Liu; Xiao-Lan Cao

    2015-01-01

    Background:The Composite International Diagnostic Interview-3.0 (CIDI-3.0) is a fully structured lay-administered diagnostic interview for the assessment of mental disorders according to ICD-10 and Diagnostic and Statistical Manual of Mental Disorders,Fourth Edition (DSM-Ⅳ) criteria.The aim of the study was to investigate the concurrent validity of the Chinese CIDI in diagnosing mental disorders in psychiatric settings.Methods:We recruited 208 participants,of whom 148 were patients from two psychiatric hospitals and 60 healthy people from communities.These participants were administered with CIDI by six trained lay interviewers and the Structured Clinical Interview for DSM-Ⅳ Axis I Disorders (SCID-I,gold standard) by two psychiatrists.Agreement between CIDI and SCID-I was assessed with sensitivity,specificity,positive predictive value and negative predictive value.Individual-level CIDI-SCID diagnostic concordance was evaluated using the area under the receiver operator characteristic curve and Cohen's K.Results:Substantial to excellent CIDI to SCID concordance was found for any substance use disorder (area under the receiver operator characteristic curve [AUC] =0.926),any anxiety disorder (AUC =0.807) and any mood disorder (AUC =0.806).The concordance between the CIDI and the SCID for psychotic and eating disorders is moderate.However,for individual mental disorders,the CIDI-SCID concordance for bipolar disorders (AUC =0.55) and anorexia nervosa (AUC =0.50) was insufficient.Conclusions:Overall,the Chinese version of CIDI-3.0 has acceptable validity in diagnosing the substance use disorder,anxiety disorder and mood disorder among Chinese adult population.However,we should be cautious when using it for bipolar disorders and anorexia nervosa.

  4. Validity of Chinese Version of the Composite International Diagnostic Interview-3.0 in Psychiatric Settings

    Directory of Open Access Journals (Sweden)

    Jin Lu

    2015-01-01

    Full Text Available Background: The Composite International Diagnostic Interview-3.0 (CIDI-3.0 is a fully structured lay-administered diagnostic interview for the assessment of mental disorders according to ICD-10 and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV criteria. The aim of the study was to investigate the concurrent validity of the Chinese CIDI in diagnosing mental disorders in psychiatric settings. Methods: We recruited 208 participants, of whom 148 were patients from two psychiatric hospitals and 60 healthy people from communities. These participants were administered with CIDI by six trained lay interviewers and the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I, gold standard by two psychiatrists. Agreement between CIDI and SCID-I was assessed with sensitivity, specificity, positive predictive value and negative predictive value. Individual-level CIDI-SCID diagnostic concordance was evaluated using the area under the receiver operator characteristic curve and Cohen′s K. Results: Substantial to excellent CIDI to SCID concordance was found for any substance use disorder (area under the receiver operator characteristic curve [AUC] = 0.926, any anxiety disorder (AUC = 0.807 and any mood disorder (AUC = 0.806. The concordance between the CIDI and the SCID for psychotic and eating disorders is moderate. However, for individual mental disorders, the CIDI-SCID concordance for bipolar disorders (AUC = 0.55 and anorexia nervosa (AUC = 0.50 was insufficient. Conclusions: Overall, the Chinese version of CIDI-3.0 has acceptable validity in diagnosing the substance use disorder, anxiety disorder and mood disorder among Chinese adult population. However, we should be cautious when using it for bipolar disorders and anorexia nervosa.

  5. Institutional Structure and International Competitiveness Relationship in Developed Countries

    Directory of Open Access Journals (Sweden)

    Aynur Yıldırım

    2016-06-01

    Full Text Available This study analyzes the effects of institutional structure on the international competitiveness of developed countries econometrically by employing a “Panel Data Analysis” with a sample of 21 developed countries and 23 institutional variables for the period 2000-2011. The results of the analysis indicate that while judicial independence, protection of intellectual property rights, integrity of the juridical system, marginal tax, political freedoms, black market exchange rate, restrictions on foreign investment, private sector’s share in the banking system, hiring-minimum wage, and hiring-dismissal have a positive effect; the nature of legal arrangements, government spending, transfers and subsidies, civil liberties, tariffs, regulations regarding trade barriers, collective bargaining, and military tutelage have a negative effect on the international competitiveness of developed countries.

  6. STRUCTURAL ECONOMIC CHANGE AND INTERNATIONAL MIGRATION FROM MEXICO AND POLAND

    Science.gov (United States)

    Massey, Douglas S.; Kalter, Frank; Pren, Karen A.

    2010-01-01

    In this article we use uniquely comparable data sets from two very different settings to examine how exogenous economic transformations affect the likelihood and selectivity of international out-migration. Specifically, we use data from the Mexican Migration Project to construct event history files predicting first U.S. trips from seven communities in the state of Veracruz, which until recently sent very few migrants abroad. Similarly, using data from the Polish Migration Project, we derive comparable event history files predicting first trips to Germany from four Polish communities, which also sent few migrants abroad before the 1980s. Our analyses suggest that the onset of structural adjustment in both places had a significant effect in raising the probability of international migration, even when controlling for a set of standard variables specified by other theories to influence migration propensity, such as the size of the binational income gap and various indicators of human and social capital. PMID:21765550

  7. Project on strengthening of structures using advanced composites

    Directory of Open Access Journals (Sweden)

    Recuero, A.

    1997-12-01

    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

  8. Compositions comprising enhanced graphene oxide structures and related methods

    Science.gov (United States)

    Kumar, Priyank Vijaya; Bardhan, Neelkanth M.; Belcher, Angela; Grossman, Jeffrey

    2016-12-27

    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.

  9. Hierarchical Composites with Nanostructured Reinforcement for Multifunctional Aerospace Structures

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced nano-engineered composites hold great potential for augmenting aerospace composites material performance by reducing spacecraft weight, increasing payload...

  10. Fast flexible modeling of RNA structure using internal coordinates.

    Science.gov (United States)

    Flores, Samuel Coulbourn; Sherman, Michael A; Bruns, Christopher M; Eastman, Peter; Altman, Russ Biagio

    2011-01-01

    Modeling the structure and dynamics of large macromolecules remains a critical challenge. Molecular dynamics (MD) simulations are expensive because they model every atom independently, and are difficult to combine with experimentally derived knowledge. Assembly of molecules using fragments from libraries relies on the database of known structures and thus may not work for novel motifs. Coarse-grained modeling methods have yielded good results on large molecules but can suffer from difficulties in creating more detailed full atomic realizations. There is therefore a need for molecular modeling algorithms that remain chemically accurate and economical for large molecules, do not rely on fragment libraries, and can incorporate experimental information. RNABuilder works in the internal coordinate space of dihedral angles and thus has time requirements proportional to the number of moving parts rather than the number of atoms. It provides accurate physics-based response to applied forces, but also allows user-specified forces for incorporating experimental information. A particular strength of RNABuilder is that all Leontis-Westhof basepairs can be specified as primitives by the user to be satisfied during model construction. We apply RNABuilder to predict the structure of an RNA molecule with 160 bases from its secondary structure, as well as experimental information. Our model matches the known structure to 10.2 Angstroms RMSD and has low computational expense.

  11. 8th international conference on electronic spectroscopy and structure

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Art

    2000-10-16

    Gathering from 33 countries around the world, 408 registrants and a number of local drop-in participants descended on the Clark Kerr Campus of the University of California, Berkeley, from Monday, August 7 through Saturday, August 12, 2000 for the Eighth International Conference on Electronic Structure and Spectroscopy (ICESS8). At the conference, participants benefited from an extensive scientific program comprising more than 100 oral presentations (plenary lectures and invited and contributed talks) and 330 poster presentations, as well as ample time for socializing and a tour of the Advanced Light Source (ALS) at the nearby Lawrence Berkeley National Laboratory.

  12. Propagation of internal stresses in composite materials during heating and cooling according to thermal cycles of welding

    International Nuclear Information System (INIS)

    Gukasyan, L.E.; Belov, V.V.

    1977-01-01

    Investigations of free thermal expansion of a composite material, of fibre and matrix during welding thermal cycle make it possible to estimate mean internal strain and stress in the composite components, as well as the residual internal stress and strain present in the composite material after manufacturing. The samples investigated consisted of nickel-chromium EhI445 alloy, reinforced by tungsten-rhenium alloy fibres. As the composite material was cooled and heated in course of welding, the stress and strain changed their sign twice, the first time upon heating, the second time upon cooling. After complete cooling of the composite material residual stresses in the fibre stay at the proportionality level, while those in the matrix are lower. Experimental evidence of internal stress and strain appearing in the composite material during heating are fairly consistent with calculations in the elastic region, if account is taken of the temperature of internal residual stress relaxation upon heating

  13. Buckling optimization of steering stiffeners for grid-stiffened composite structures

    NARCIS (Netherlands)

    Wang, D.; Abdalla, M.M.

    2015-01-01

    Grid-stiffened composite structures, where the skin is stiffened by a lattice of stiffeners, not only allow for significant reduction in structural weight but are also competitive in terms of structural stability and damage tolerance compared with sandwich composite structures. As the development of

  14. Material Distribution Optimization for the Shell Aircraft Composite Structure

    Science.gov (United States)

    Shevtsov, S.; Zhilyaev, I.; Oganesyan, P.; Axenov, V.

    2016-09-01

    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.

  15. 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)

    2006-07-01

    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)

  16. Mechanistic Effects of Porosity on Structural Composite Materials

    Science.gov (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.

  17. Structural ceramic coatings in composite microtruss cellular materials

    Energy Technology Data Exchange (ETDEWEB)

    Bele, E.; Bouwhuis, B.A.; Codd, C. [Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario (Canada); Hibbard, G.D., E-mail: glenn.hibbard@utoronto.ca [Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario (Canada)

    2011-09-15

    Graphical abstract: The compressive strength increase per unit sleeve thickness of Al cores reinforced with Al{sub 2}O{sub 3} sleeves is lower than the corresponding strength increase when the same cores are reinforced with nanocrystalline Ni (n-Ni) sleeves (left). However, because anodizing is a transformative surface treatment, the Al{sub 2}O{sub 3} coating was able to achieve this performance increase with little overall weight penalty (right). Display Omitted Highlights: {yields} A new type of metal/ceramic microtruss cellular composite has been created. {yields} Reinforcing sleeves of Al{sub 2}O{sub 3} were deposited on low density Al microtruss cores. {yields} Significant compressive strength increases were seen at virtually no weight penalty. {yields} Failure mechanisms were studied by electron microscopy and finite element analysis. {yields} Buckling, sleeve wrinkling, and coating fracture dictated the compressive strength. - Abstract: In the present study, anodizing was used to produce Al{sub 2}O{sub 3} coatings in a conventional 3003 aluminum alloy microtruss core; a 38.5 {mu}m thick anodic coating provided a 143% increase in compressive strength. Finite-element analyses were used to illustrate the dependence of the compressive strength and failure mechanism on the thickness of the anodic coating. At low thicknesses the microtruss strength is dictated by global bucking of the internal struts. However, at higher thicknesses the compressive strength is controlled by coating fracture and local deformation in the hinge region of the struts. Regardless of the failure mechanism, the compressive strength of the composite microtruss increased with increasing anodic coating thickness, with very little corresponding weight penalty.

  18. Structural ceramic coatings in composite microtruss cellular materials

    International Nuclear Information System (INIS)

    Bele, E.; Bouwhuis, B.A.; Codd, C.; Hibbard, G.D.

    2011-01-01

    Graphical abstract: The compressive strength increase per unit sleeve thickness of Al cores reinforced with Al 2 O 3 sleeves is lower than the corresponding strength increase when the same cores are reinforced with nanocrystalline Ni (n-Ni) sleeves (left). However, because anodizing is a transformative surface treatment, the Al 2 O 3 coating was able to achieve this performance increase with little overall weight penalty (right). Display Omitted Highlights: → A new type of metal/ceramic microtruss cellular composite has been created. → Reinforcing sleeves of Al 2 O 3 were deposited on low density Al microtruss cores. → Significant compressive strength increases were seen at virtually no weight penalty. → Failure mechanisms were studied by electron microscopy and finite element analysis. → Buckling, sleeve wrinkling, and coating fracture dictated the compressive strength. - Abstract: In the present study, anodizing was used to produce Al 2 O 3 coatings in a conventional 3003 aluminum alloy microtruss core; a 38.5 μm thick anodic coating provided a 143% increase in compressive strength. Finite-element analyses were used to illustrate the dependence of the compressive strength and failure mechanism on the thickness of the anodic coating. At low thicknesses the microtruss strength is dictated by global bucking of the internal struts. However, at higher thicknesses the compressive strength is controlled by coating fracture and local deformation in the hinge region of the struts. Regardless of the failure mechanism, the compressive strength of the composite microtruss increased with increasing anodic coating thickness, with very little corresponding weight penalty.

  19. Design and Analysis of a Stiffened Composite Structure Repair Concept

    Science.gov (United States)

    Przekop, Adam

    2011-01-01

    A design and analysis of a repair concept applicable to a stiffened thin-skin composite panel based on the Pultruded Rod Stitched Efficient Unitized Structure is presented. Since the repair concept is a bolted repair using metal components, it can easily be applied in the operational environment. Initial analyses are aimed at validating the finite element modeling approach by comparing with available test data. Once confidence in the analysis approach is established several repair configurations are explored and the most efficient one presented. Repairs involving damage to the top of the stiffener alone are considered in addition to repairs involving a damaged stiffener, flange and underlying skin. High fidelity finite element modeling techniques such as mesh-independent definition of compliant fasteners, elastic-plastic metallic material properties and geometrically nonlinear analysis are utilized in the effort. The results of the analysis are presented and factors influencing the design are assessed and discussed.

  20. Giant Planets of Our Solar System Atmospheres, Composition, and Structure

    CERN Document Server

    Irwin, Patrick G. J

    2009-01-01

    This book reviews the current state of knowledge of the atmospheres of the giant gaseous planets: Jupiter, Saturn, Uranus, and Neptune. The current theories of their formation are reviewed and their recently observed temperature, composition and cloud structures are contrasted and compared with simple thermodynamic, radiative transfer and dynamical models. The instruments and techniques that have been used to remotely measure their atmospheric properties are also reviewed, and the likely development of outer planet observations over the next two decades is outlined. This second edition has been extensively updated following the Cassini mission results for Jupiter/Saturn and the newest ground-based measurements for Uranus/Neptune as well as on the latest development in the theories on planet formation.

  1. Constraints on Composition, Structure and Evolution of the Lithosphere

    Science.gov (United States)

    Bianchini, Gianluca; Bonadiman, Costanza; Aulbach, Sonja; Schutt, Derek

    2015-05-01

    The idea for this special issue was triggered at the Goldschmidt Conference held in Florence (August 25-30, 2013), where we convened a session titled "Integrated Geophysical-Geochemical Constraints on Composition and Structure of the Lithosphere". The invitation to contribute was extended not only to the session participants but also to a wider spectrum of colleagues working on related topics. Consequently, a diverse group of Earth scientists encompassing geophysicists, geodynamicists, geochemists and petrologists contributed to this Volume, providing a comprehensive overview on the nature and evolution of lithospheric mantle by combining studies that exploit different types of data and interpretative approaches. The integration of geochemical and geodynamic datasets and their interpretation represents the state of the art in our knowledge of the lithosphere and beyond, and could serve as a blueprint for future strategies in concept and methodology to advance our knowledge of this and other terrestrial reservoirs.

  2. Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design, volume 3

    Science.gov (United States)

    Soderquist, Joseph R. (Compiler); Neri, Lawrence M. (Compiler); Bohon, Herman L. (Compiler)

    1992-01-01

    This publication contains the proceedings of the Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design held at Lake Tahoe, Nevada, during 4-7 Nov. 1991. Presentations were made in the following areas of composite structural design: perspectives in composites, design methodology, design applications, design criteria, supporting technology, damage tolerance, and manufacturing.

  3. Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design, volume 1

    Science.gov (United States)

    Soderquist, Joseph R. (Compiler); Neri, Lawrence M. (Compiler); Bohon, Herman L. (Compiler)

    1992-01-01

    This publication contains the proceedings of the Ninth DOD/NASA/FAA conference on Fibrous Composites in structural Design. Presentations were made in the following areas of composite structural design: perspectives in composites; design methodology; design applications; design criteria; supporting technology; damage tolerance; and manufacturing.

  4. Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design, volume 2

    Science.gov (United States)

    Soderquist, Joseph R. (Compiler); Neri, Lawrence M. (Compiler); Bohon, Herman L. (Compiler)

    1992-01-01

    This publication contains the proceedings of the Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design held at Lake Tahoe, Nevada, during 4-7 Nov. 1991. Presentations were made in the following areas of composite structural design: perspectives in composites, design methodology, design applications, design criteria, supporting technology, damage tolerance, and manufacturing.

  5. Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design, volume 1

    Energy Technology Data Exchange (ETDEWEB)

    Soderquist, J.R.; Neri, L.M.; Bohon, H.L.

    1992-09-01

    This publication contains the proceedings of the Ninth DOD/NASA/FAA conference on Fibrous Composites in structural Design. Presentations were made in the following areas of composite structural design: perspectives in composites; design methodology; design applications; design criteria; supporting technology; damage tolerance; and manufacturing. Separate abstracts have been indexed into the database for articles from this report.

  6. Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design, volume 2

    Energy Technology Data Exchange (ETDEWEB)

    Soderquist, J.R.; Neri, L.M.; Bohon, H.L.

    1992-09-01

    This publication contains the proceedings of the Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design held at Lake Tahoe, Nevada, during 4-7 Nov. 1991. Presentations were made in the following areas of composite structural design: perspectives in composites, design methodology, design applications, design criteria, supporting technology, damage tolerance, and manufacturing.

  7. Finite element model updating of natural fibre reinforced composite structure in structural dynamics

    Directory of Open Access Journals (Sweden)

    Sani M.S.M.

    2016-01-01

    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.

  8. Characterization of adhesive from oysters: A structural and compositional study

    Science.gov (United States)

    Alberts, Erik

    The inability for man-made adhesives to set in wet or humid environments is an ongoing challenging the design of biomedical and marine adhesive materials. However, we see that nature has already overcome this challenge. Mussels, barnacles, oysters and sandcastle worms all have unique mechanisms by which they attach themselves to surfaces. By understanding what evolution has already spent millions of years perfecting, we can design novel adhesive materials inspired by nature's elegant designs. The well-studied mussel is currently the standard for design of marine inspired biomimetic polymers. In the work presented here, we aim to provide new insights into the adhesive produced by the eastern oyster, Crassostrea virginica. Unlike the mussel, which produces thread-like plaques comprised of DOPA containing-protein, the oyster secretes an organic-inorganic hybrid adhesive as it settles and grows onto a surface. This form of adhesion renders the oyster to be permanently fixed in place. Over time, hundreds of thousands of oyster grow and agglomerate to form extensive reef structures. These reefs are not only essential to survival of the oyster, but are also vital to intertidal ecosystems. While the shell of the oyster has been extensively studied, curiously, only a few conflicting insights have been made into the nature of the adhesive and contact zone between shell and substrate, and even lesfs information has been ascertained on organic and inorganic composition. In this work, we provide microscopy and histochemical studies to characterize the structure and composition of the adhesive, using oyster in the adult and juvenile stages of life. Preliminary work on extracting and characterizing organic components through collaborative help with solid-state NMR (SSNMR) and proteomics are also detailed here. We aim to provide a full, comprehensive characterization of oyster adhesive so that in the future, we may apply what we learn to the design of new materials.

  9. Vegetation composition and structure significantly influence green roof performance

    Energy Technology Data Exchange (ETDEWEB)

    Dunnett, N.; Nagase, A.; Booth, R.; Grime, P. [Sheffield Univ., Sheffield (United Kingdom). Dept. of Landscape Architecture

    2005-07-01

    The majority of published literature on green roofs contains little specific information on the contribution of plants to the various functions and properties of green roofs. This paper reviewed previously published material in an attempt to shed light on the role of vegetation composition in green roof systems, with specific reference to hydrology and biodiversity support. Two ongoing experiments at the University of Sheffield were then considered: (1) a comparison of quality and quantity of runoff from different types of vegetation; and (2) a comparison of flowering seasons and biodiversity support of different vegetation. Results of the studies showed that there was no general pattern of variation in runoff that could be related to vegetation complexity or taxonomic composition of the communities. During the winter months, high precipitation quickly saturated the soil and percolate losses were similar for all treatments. In the summer, throughflow losses differed between treatments in relation to the structure of the plant canopy. Differing mechanisms resulted in variations in the volume of percolate that was collected. Lower volumes of percolate were observed in herb-only monocultures of Leontdon hispidus, a species with a high water content. Tap-rooted species were seen to more effectively absorb soil moisture. The biodiversity support study focused on the study of Sedum species and Labiatae species, which suggested that mixed vegetation containing these species had a far greater likelihood of attracting wild bees to support pollination. Results of the studies indicated that green roof vegetation with greater structural and species diversity may provide different benefits than sedum-dominated roots. Further studies are needed to investigate the trade-offs between vegetation types, and green roof functions and performance in order to justify calls for a wider diversity of green roof types. 8 refs., 2 tabs., 1 fig.

  10. The effects of embedded piezoelectric fiber composite sensors on the structural integrity of glass-fiber–epoxy composite laminate

    International Nuclear Information System (INIS)

    Konka, Hari P; Wahab, M A; Lian, K

    2012-01-01

    Piezoelectric fiber composite sensors (PFCSs) made from micro-sized lead zirconate titanate (PZT) fibers have many advantages over the traditional bulk PZT sensors for embedded sensor applications. PFCSs as embedded sensors will be an ideal choice to continuously monitor the stress/strain levels and health conditions of composite structures. PFCSs are highly flexible, easily embeddable, have high compatibility with composite structures, and also provides manufacturing flexibility. This research is focused on examining the effects of embedding PFCS sensors (macro-fiber composite (MFC) and piezoelectric fiber composite (PFC)) on the structural integrity of glass-fiber–epoxy composite laminates. The strengths of composite materials with embedded PFCSs and conventional PZT sensors were compared, and the advantages of PFCS sensors over PZTs were demonstrated. Initially a numerical simulation study is performed to understand the local stress/strain field near the embedded sensor region inside a composite specimen. High stress concentration regions were observed near the embedded sensor corner edge. Using PFCS leads to a reduction of 56% in longitudinal stress concentration and 38% in transverse stress concentration, when compared to using the conventional PZTs as embedded sensors. In-plane tensile, in-plane tension–tension fatigue, and short beam strength tests are performed to evaluate the strengths/behavior of the composite specimens containing embedded PFCS. From the tensile test it is observed that embedding PFCS and PZT sensors in the composite structures leads to a reduction in ultimate strength by 3 and 6% respectively. From the fatigue test results it is concluded that both embedded PFCS and PZT sensors do not have a significant effect on the fatigue behavior of the composite specimens. From the short beam strength test it is found that embedding PFCS and PZT sensors leads to a reduction in shear strength by 7 and 15% respectively. Overall the pure PZT

  11. The effects of embedded piezoelectric fiber composite sensors on the structural integrity of glass-fiber-epoxy composite laminate

    Science.gov (United States)

    Konka, Hari P.; Wahab, M. A.; Lian, K.

    2012-01-01

    Piezoelectric fiber composite sensors (PFCSs) made from micro-sized lead zirconate titanate (PZT) fibers have many advantages over the traditional bulk PZT sensors for embedded sensor applications. PFCSs as embedded sensors will be an ideal choice to continuously monitor the stress/strain levels and health conditions of composite structures. PFCSs are highly flexible, easily embeddable, have high compatibility with composite structures, and also provides manufacturing flexibility. This research is focused on examining the effects of embedding PFCS sensors (macro-fiber composite (MFC) and piezoelectric fiber composite (PFC)) on the structural integrity of glass-fiber-epoxy composite laminates. The strengths of composite materials with embedded PFCSs and conventional PZT sensors were compared, and the advantages of PFCS sensors over PZTs were demonstrated. Initially a numerical simulation study is performed to understand the local stress/strain field near the embedded sensor region inside a composite specimen. High stress concentration regions were observed near the embedded sensor corner edge. Using PFCS leads to a reduction of 56% in longitudinal stress concentration and 38% in transverse stress concentration, when compared to using the conventional PZTs as embedded sensors. In-plane tensile, in-plane tension-tension fatigue, and short beam strength tests are performed to evaluate the strengths/behavior of the composite specimens containing embedded PFCS. From the tensile test it is observed that embedding PFCS and PZT sensors in the composite structures leads to a reduction in ultimate strength by 3 and 6% respectively. From the fatigue test results it is concluded that both embedded PFCS and PZT sensors do not have a significant effect on the fatigue behavior of the composite specimens. From the short beam strength test it is found that embedding PFCS and PZT sensors leads to a reduction in shear strength by 7 and 15% respectively. Overall the pure PZT sensors

  12. Darlington GS vacuum building - internal structures and foundation

    International Nuclear Information System (INIS)

    Huterer, J.; Brown, D.G.; Yanchula, S.

    1985-01-01

    This paper describes the evolution of the internal structure from initial concept to final design. Fundamental changes to the original configuration were precipitated by the action of large seismic forces acting on a top-heavy configuration. Prestressing was eliminated in deference to high humidity. Aspects of the elevated water tank's peripheral support beam are discussed vis-a-vis an adjacent slipforming operation, and practical construction limitations on steel placement. Also reviewed are the shortening of peripheral columns due to shrinkage and creep, and considerations of crack control for purposes of water-tightness. The authors justify the choice of stainless steel for fabrication of the siphon system's riser pipes. The foundation slab must resist the combined effects of vacuum pressure, hydrostatic uplift, and the seismic reactions of the internal structure and perimeter wall. The dependency of a key foundation component, the gallery roof slab, on the dome tendon layout is high-lighted; and aspects of its constructability are reviewed in light of congestion of vertical tendon anchorages, and of reinforcement. The design of the air-tight slab liner is reviewed, attention focusing on weld design under vacuum and accident temperature loads; on corrosion protection; and on the related construction access bulkhead - its ASME requirements and fabrication tolerances. (orig.)

  13. PIV measurement of internal structure of diesel fuel spray

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Z M [Ecotechnology System Lab., Yokohama National Univ. (Japan); Nishino, K [Div. of Artificial Environment and Systems, Yokohama National Univ. (Japan); Mizuno, S [Yokohama National Univ. (Japan); Torii, K [Dept. of Mechanical Engineering and Materials Science, Yokohama National Univ. (Japan)

    2000-12-01

    This paper reports particle image velocimetry (PIV) measurements of diesel fuel spray injected from a single-hole nozzle at injection pressures ranging from 30 to 70 MPa, which are comparable to partial-load operating conditions of commercial diesel engines. The fuel is injected into a non-combusting environment pressurized up to 2.0 MPa. A laser-induced fluorescent (LIF) technique is utilized to visualize internal structures of fuel sprays formed by densely-distributing droplets. A specially designed synchronization system is developed to acquire double-frame spray images at an arbitrary time delay after injection. A direct cross-correlation PIV technique is applied to measure instantaneous droplet velocity distribution. Unique large-scale structures in droplet concentration, called 'branch-like structures' by Azetsu et al. (1990), are observed and shown to be associated with active vortical motions, which appear to be responsible for the mixing between droplets and the surrounding gas. It is found that the droplets tend to move out of the vortical structures and accumulate in the regions of low vorticity. Some other interesting features concerning droplet velocity fields are also presented. (orig.)

  14. Ultimate internal pressure capacity of concrete containment structures

    International Nuclear Information System (INIS)

    Krishnaswamy, C.N.; Namperumal, R.; Al-Dabbagh, A.

    1983-01-01

    Lesson learned from the accident at Three-Mile Island nuclear plant has necessitated the computation of the ultimate internal pressure capacity of containment structures as a licensing requirement in the U.S. In general, a containment structure is designed to be essentially elastic under design accident pressure. However, as the containment pressure builds up beyond the design value due to a more severe postulated accident, the containment response turns nonlinear as it sequentially passes through cracking of concrete, yielding of linear plate, yielding of rebar, and yielding of post-tensioning tendon (if the containment concrete is prestressed). This paper reports on the determination of the ultimate internal pressure capacity and nonlinear behavior of typical reinforced and prestressed concrete BWR containments. The probable modes of failure, the criteria for ultimate pressure capacity, and the most critical sections are described. Simple equations to hand-calculate the ultimate pressure capacity and the nonlinear behavior at membrane sections of the containment shell are presented. A nonlinear finite element analysis performed to determine the nonlinear behavior of the entire shell including nonmembrane sections is briefly discribed. The analysis model consisted of laminated axisymmetric shell finite elements with nonlinear stress-strain properties for each material. Results presented for typical BWR concrete containments include nonlinear response plots of internal pressure versus containment deflection and strains in the liner, rebar, and post-tensioning tendons at the most stressed section in the shell. Leak-tightness of the containment liner and the effect of thermal loads on the ultimate capacity are discussed. (orig.)

  15. Control of internal and external short circuits in lithium batteries using a composite thermal switch

    Science.gov (United States)

    Mcdonald, Robert C.; Pickett, Jerome; Goebel, Franz

    1991-01-01

    A composite material has been developed, consisting of a blend of metal and fluorocarbon particles, which behaves as an electronic conductor at room temperature and which abruptly becomes an insulator at a predetermined temperature. This switching behavior results from the difference in thermal expansion coefficients between the conductive and non-conductive portions of the composite. This material was applied as a thin film between the carbon cathode in Li/SOCl2 cells, and the metallic cathode current collector. Using test articles incorporating this feature it was shown that lithium cells externally heated or internally heated during a short circuit lost rate capability and the ability to overheat well below the melting point of lithium (180 C). Thus, during an internal or external cell short circuit, the potential for thermal runaway involving reactions of molten lithium is avoided.

  16. Structural design and fabrication techniques of composite unmanned aerial vehicles

    Science.gov (United States)

    Hunt, Daniel Stephen

    Popularity of unmanned aerial vehicles has grown substantially in recent years both in the private sector, as well as for government functions. This growth can be attributed largely to the increased performance of the technology that controls these vehicles, as well as decreasing cost and size of this technology. What is sometimes forgotten though, is that the research and advancement of the airframes themselves are equally as important as what is done with them. With current computer-aided design programs, the limits of design optimization can be pushed further than ever before, resulting in lighter and faster airframes that can achieve longer endurances, higher altitudes, and more complex missions. However, realization of a paper design is still limited by the physical restrictions of the real world and the structural constraints associated with it. The purpose of this paper is to not only step through current design and manufacturing processes of composite UAVs at Oklahoma State University, but to also focus on composite spars, utilizing and relating both calculated and empirical data. Most of the experience gained for this thesis was from the Cessna Longitude project. The Longitude is a 1/8 scale, flying demonstrator Oklahoma State University constructed for Cessna. For the project, Cessna required dynamic flight data for their design process in order to make their 2017 release date. Oklahoma State University was privileged enough to assist Cessna with the mission of supporting the validation of design of their largest business jet to date. This paper will detail the steps of the fabrication process used in construction of the Longitude, as well as several other projects, beginning with structural design, machining, molding, skin layup, and ending with final assembly. Also, attention will be paid specifically towards spar design and testing in effort to ease the design phase. This document is intended to act not only as a further development of current

  17. Towards better description of solar activity variation in the International Reference Ionosphere topside ion composition model

    Czech Academy of Sciences Publication Activity Database

    Truhlík, Vladimír; Bilitza, D.; Třísková, Ludmila

    2015-01-01

    Roč. 55, č. 8 (2015), s. 2099-2105 ISSN 0273-1177 R&D Projects: GA MŠk(CZ) LH11123 Institutional support: RVO:68378289 Keywords : ion composition * topside ionosphere * solar activity * empirical model * International Reference Ionosphere Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.409, year: 2015 http://www.sciencedirect.com/science/article/pii/S027311771400489X

  18. Marginal and internal fit of nano-composite CAD/CAM restorations

    Directory of Open Access Journals (Sweden)

    So-Hyun Park

    2016-02-01

    Full Text Available Objectives The purpose of this study was to compare the marginal and internal fit of nano-composite CAD-CAM restorations. Materials and Methods A full veneer crown and an mesio-occluso-distal (MOD inlay cavity, which were prepared on extracted human molars, were used as templates of epoxy resin replicas. The prepared teeth were scanned and CAD-CAM restorations were milled using Lava Ultimate (LU and experimental nano-composite CAD/CAM blocks (EB under the same milling parameters. To assess the marginal and internal fit, the restorations were cemented to replicas and were embedded in an acrylic mold for sectioning at 0.5 mm intervals. The measured gap data were pooled according to the block types and measuring points for statistical analysis. Results Both the block type and measuring point significantly affected gap values, and their interaction was significant (p = 0.000. In crowns and inlays made from the two blocks, gap values were significantly larger in the occlusal area than in the axial area, while gap values in the marginal area were smallest (p < 0.001. Among the blocks, the restorations milled from EB had a significantly larger gap at all measuring points than those milled from LU (p = 0.000. Conclusions The marginal and internal gaps of the two nano-composite CAD/CAM blocks differed according to the measuring points. Among the internal area of the two nano-composite CAD/CAM restorations, occlusal gap data were significantly larger than axial gap data. The EB crowns and inlays had significantly larger gaps than LU restorations.

  19. SAFE-3D, Stress Analysis of 3-D Composite Structure by Finite Elements Method

    International Nuclear Information System (INIS)

    Cornell, D.C.; Jadhav, K.; Crowell, J.S.

    1969-01-01

    1 - Description of problem or function: SAFE-3D is a finite-element program for the three-dimensional elastic analysis of heterogeneous composite structures. The program uses the following types of finite elements - (1) tetrahedral elements to represent the continuum, (2) triangular plane stress membrane elements to represent inner liner or outer case, and (3) uniaxial tension-compression elements to represent internal reinforcement. The structure can be of arbitrary geometry and have any distribution of material properties, temperatures, surface loadings, and boundary conditions. 2 - Method of solution: The finite-element variational method is used. Equilibrium equations are solved by the alternating component iterative method. 3 - Restrictions on the complexity of the problem - Maxima of: 5000 nodes; 16000 elements. The program cannot be applied to incompressible solids and is not recommended for Poisson's ratio in the range of nu between 0.495 and 0.5

  20. Analysis of neutron diffraction peak broadening caused by internal stresses in composite materials

    International Nuclear Information System (INIS)

    Todd, R.I.; Borsa, C.; Derby, B.

    1994-01-01

    Neutron diffraction is an essential tool in the study of internal stresses in composite materials. In most work only the peak shifts caused by the related elastic strains are considered, but other valuable information exists in the form of peak shape changes. The conditions under which the pure diffraction profile of the composite (i.e. the profile when all sources of broadening not caused by the residual stresses are removed) represents the probability distribution of the peak shifts corresponding to the strains are examined. It is shown that in these conditions, the pure diffraction profile has no attributes of particle size broadening (and vice versa), thereby providing a test for the validity of results interpreted in this way. The experimental derivation of measured strain distributions in Al 2 O 3 /SiCp composites using neutron diffraction is described. No apparent particle size broadening was detected, demonstrating the validity of the results, which also satisfied other tests for consistency

  1. Effect of dielectrophoretic structuring on piezoelectric and pyroelectric properties of lead titanate-epoxy composites

    NARCIS (Netherlands)

    Khanbareh, H.; Zwaag, S. van der; Groen, W.A.

    2014-01-01

    Functional granular composites of lead titanate particles in an epoxy matrix prepared by dielectrophoresis show enhanced dielectric, piezoelectric and pyroelectric properties compared to 0-3 composites for different ceramic volume content from 10% to 50%. Two structuring parameters, the

  2. Internal Structure of Charged Particles in a GRT Gravitational Model

    Science.gov (United States)

    Khlestkov, Yu. A.; Sukhanova, L. A.

    2018-05-01

    With the help of an exact solution of the Einstein and Maxwell equations, the internal structure of a multiply connected space of wormhole type with two unclosed static throats leading out of it into two parallel vacuum spaces or into one space is investigated in GRT for a free electric field and dust-like matter. The given geometry is considered as a particle-antiparticle pair with fundamental constants arising in the form of first integrals in the solution of the Cauchy problem - electric charges ±e of opposite sign in the throats and rest mass m0 - the total gravitational mass of the inner world of the particle in the throat. With the help of the energy conservation law, the unremovable rotation of the internal structure is included and the projection of the angular momentum of which onto the rotation axis is identified with the z-projection of the spin of the charged particle. The radius of 2-Gaussian curvature of the throat R* is identified with the charge radius of the particle, and the z-projection of the magnetic moment and the g-factor are found. The feasibility of the given gravitational model is confirmed by the found condition of independence of the spin quantum number of the electron and the proton s = 1/2 of the charge radius R* and the relativistic rest mass m* of the rotating throat, which is reliably confirmed experimentally, and also by the coincidence with high accuracy of the proton radius calculated in the model R*p = 0.8412·10-13 cm with the value of the proton charge radius obtained experimentally by measuring the Lamb shift on muonic hydrogen. The electron in the given model also turns out to be a structured particle with radius R*e = 3.8617·10-11 cm.

  3. Evolution of the structure and the phase composition of a bainitic structural steel during plastic deformation

    Science.gov (United States)

    Nikitina, E. N.; Glezer, A. M.; Ivanov, Yu. F.; Aksenova, K. V.; Gromov, V. E.; Kazimirov, S. A.

    2017-10-01

    The evolution of the phase composition and the imperfect substructure of the 30Kh2N2MFA bainitic structural steel subjected to compressive deformation by 36% is quantitatively analyzed. It is shown that deformation is accompanied by an increase in the scalar dislocation density, a decrease in the longitudinal fragment sizes, an increase in the number of stress concentrators, the dissolution of cementite particles, and the transformation of retained austenite.

  4. IR thermography methods for evaluation of internal defects in light composite armours

    International Nuclear Information System (INIS)

    Swiderski, W.; Szabra, D.; Szudrowicz, M.

    2009-01-01

    Complete text of publication follows. Light composite armour is a preferred solution against military and paramilitary sources of present threats as the reducing mass of battle vehicles provides a possibility of their quick air-transport. The light armours of these vehicles should be resistant against: common and rifle bullets, grenades, anti-personal mines, IED - improvised explosive devices. The range of military applications anticipated for composite armours covers a broad spectrum of materials and designs. Materials of composite armours include graphite epoxy, glass epoxy and aramid fiber composites. The composites that have been examined can include a variety of defects, such as ballistic impacts, embedded defects, manufacturing defects, thermal damage, moisture ingress and other induced defects. Methods for testing ballistic protection of light armours are known and used. First of all they consist of checking armours resistance against the bullets where the bullet velocity is known. Moreover the V50 velocity is defined during the test. In this method the V 50 velocity of a round or standard fragment is defined (according to STANAG 2920) as the velocity at which armour is penetrated at the probability 50%. The distribution of points hit by bullets or fragments on the surface of an armour is also important. In fact, only correct distribution of these points provides a guaranty for an impartial assessment of tested designs. After hitting by a bullet, shape and size of an area of damage in composite armours depends on the type and design of armour, and type of reinforcing material is particularly important. Knowledge of damage characteristics allows to arrange hitting points to avoid overlapping of damaged areas. Nondestructive testing by using IR thermography methods is very useful in evaluation of internal defects. In the paper we present the dependence between the energy of fragments/or bullets and the dimension of internal defects. (author)

  5. Proceedings Second International Conference on Composite Science and Technology 9 - 11 June 1998 Durban South Africa

    Science.gov (United States)

    1998-06-01

    LARRODE E., CASAMAYOR M.J. .Design and Manufacturing of 3-D continuous composite structures. CONGRESO INTERNACIONAL DE MATERIALES COMPUESTOS (ICCM VIII...construction" Robert J. Scott. [4] "Los materiales compuestos de fibra de vidrio" P. Antequera, L. Jim6nez, A. Miravete. [5] "Hull structural design...34Absorci6n de energfa en vehfculos mediante materiales compuestos de matriz orginica". Actas del I Congreso Nacional de Materiales Compuestos - Sevilla

  6. Structure, composition and function of interfaces in ceramic fibre/matrix composites

    International Nuclear Information System (INIS)

    Pippel, E.

    1993-01-01

    Improving the properties of fibre reinforced ceramics and glasses by optimizing their microstructure requires the knowledge of this structure down to the atomic level. In these materials energy-dissipative processes during fracture particularly act within an interface layer or layer system between fibre and matrix which can either be produced by fibre coating, or which develops during the processing of the composites. Examples are presented of the microstructural phenomena of such layers revealed by HVEM and HREM and complemented by microchemical information via a nanoscale EDXS equipment. The investigations are carried out on Nicalon fibres in Duran glass as well as on Tyranno, Nicalon and carbon fibres in different SiC-matrices. Finally, a process is discussed which may control the important interface parameters. (orig.)

  7. On the composition of modal structures of Tuvan traditional songs

    Directory of Open Access Journals (Sweden)

    Ayasmaa D.-B. Baranmaa

    2017-06-01

    Full Text Available One of the most important aspects of musical language of song folklore of Tuvans – the scale – is as yet underinvestigated in contemporary Tuvan musicology. The author is studying the effect of structural principles in scale and sound gamut of Tuvan folk songs. The theory of monodic scales (S.P. Galitskaya, E.V. Gertsman, Yu.G. Kon, Kh.S. Kushnarev, etc. forms the methodological basis for the analysis. The object of our studies are manuscripts of traditional Tuvan songs published by Russian musicologists (A. N. Aksenov, Z. K. Kyrgys, etc. serves as material base for analysis. The analysis revealed that traditional Tuvan songs are usually based on two- or three-part composite gamut structures. This significantly enriched the substantial aspect of the process by complicating types of links between the sounds, making the medium more profound, compact and complete. Scale links and subscales were detected that can interconnect in four manners (discrete, monolithic, catenary, inclusive. Conjunction principles are illustrated by a few folk songs. Catenary and inclusive manners of conjunctions have been noticed to be dominating. A vast variety of different link combinations has been detected. This is a point where intonational abundance of folklore melos reveals its inexhaustibility.

  8. Spines of the porcupine fish: Structure, composition, and mechanical properties.

    Science.gov (United States)

    Su, Frances Y; Bushong, Eric A; Deerinck, Thomas J; Seo, Kyungah; Herrera, Steven; Graeve, Olivia A; Kisailus, David; Lubarda, Vlado A; McKittrick, Joanna

    2017-09-01

    This paper explores the structure, composition, and mechanical properties of porcupine fish spines for the first time. The spine was found to be composed of nanocrystalline hydroxyapatite, protein (collagen), and water using X-ray diffraction, energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. Microstructures have mineralized fibrillar sheets in the longitudinal direction and in a radial orientation in the transverse direction that were observed using light and electron microscopy. Based on the images, the hierarchical structure of the spine shows both concentric and radial reinforcement. Mechanical properties were obtained using cantilever beam and nanoindentation tests. A tapered cantilever beam model was developed and compared to that of a uniform cantilever beam. The tapered beam model showed that while the stresses experienced were similar to those of the uniform beam, the location of the maximum stress was near the distal region of the beam rather than at the base, which allows the porcupine fish to conserve energy and resources if the spine is fractured. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Radiation-induced structural transitions in composite materials with strong interaction of polymer components

    International Nuclear Information System (INIS)

    Zaikin, Yu.A.; Koztaeva, U.P.

    2002-01-01

    In earlier papers the internal friction (IF) method was applied to studies of structural relaxation in different types of polymer-based composite materials (glass-cloth, paper-based and foiled laminates impregnated by epoxy and phenolic resins) irradiated by 2 MeV electrons in the dose range of 0.1-50.0 MGy. Selectivity and high sensibility of the internal friction method allowed to distinguish glassy transitions in different structural components of the composites. The relaxation processes observed were identified and attributed to structural alterations in the polymer filler, the binder and the boundary layers. It was shown that changes in the parameters of relaxation maximums during irradiation can be considered as quantitative characteristics for the degree of radiation-induced degradation or cross-linking of polymer molecules. This paper deals with specific features of IF spectra in paper-based laminates where both the filler fibers and the binder are strongly interacting polymers. Anisotropy of viscous and elastic properties is very weak for this kind of materials, so that IF measurements give nearly the same result independently on the filler fiber orientation in the sample. The main reasons for it are the rigid chain structure of fillers (polyethylene-terephthalate and cellulose) and the good adhesion strengthened by diffusion of the epoxy or phenolic binder to defect regions of the filler.The IF temperature dependence observed in paper-based laminates is represented by superposition of two very broad relaxation maximums associated with transitions from glassy to high-elastic state in structural components, each based on one of the polymers. The inflection points characteristic for IF temperature dependence in paper-based laminates give a reason to treat them as a superposition of α-peaks associated with transitions from glassy to high-elastic state in structural components of a composite based on the binder and the filler, respectively. Another

  10. Structural analysis of the Upper Internals Structure for the Clinch River Breeder Reactor Plant

    International Nuclear Information System (INIS)

    Houtman, J.L.

    1979-01-01

    The Upper Internals Structure (UIS) of the Clinch River Breeder Reactor Plant (CRBRP) provides control of core outlet flow to prevent severe thermal transients from occuring at the reactor vessel and primary heat transport outlet piping, provides instrumentation to monitor core performance, provides support for the control rod drivelines, and provides secondary holddown of the core. All of the structural analysis aspects of assuring the UIS is structurally adequate are presented including simplified and rigorous inelastic analysis methods, elevated temperature criteria, environmental effects on material properties, design techniques, and manufacturing constraints

  11. Carbon nanotube embedded PVDF membranes: Effect of solvent composition on the structural morphology for membrane distillation

    Science.gov (United States)

    Mapunda, Edgar C.; Mamba, Bhekie B.; Msagati, Titus A. M.

    2017-08-01

    Rapid population increase, growth in industrial and agricultural sectors and global climate change have added significant pressure on conventional freshwater resources. Tapping freshwater from non-conventional water sources such as desalination and wastewater recycling is considered as sustainable alternative to the fundamental challenges of water scarcity. However, affordable and sustainable technologies need to be applied for the communities to benefit from the treatment of non-conventional water source. Membrane distillation is a potential desalination technology which can be used sustainably for this purpose. In this work multi-walled carbon nanotube embedded polyvinylidene fluoride membranes for application in membrane distillation desalination were prepared via non-solvent induced phase separation method. The casting solution was prepared using mixed solvents (N, N-dimethylacetamide and triethyl phosphate) at varying ratios to study the effect of solvent composition on membrane morphological structures. Membrane morphological features were studied using a number of techniques including scanning electron microscope, atomic force microscope, SAXSpace tensile strength analysis, membrane thickness, porosity and contact angle measurements. It was revealed that membrane hydrophobicity, thickness, tensile strength and surface roughness were increasing as the composition of N, N-dimethylacetamide in the solvent was increasing with maximum values obtained between 40 and 60% N, N-dimethylacetamide. Internal morphological structures were changing from cellular structures to short finger-like and sponge-like pores and finally to large macro void type of pores when the amount of N, N-dimethylacetamide in the solvent was changed from low to high respectively. Multi-walled carbon nanotube embedded polyvinylidene fluoride membranes of desired morphological structures and physical properties can be synthesized by regulating the composition of solvents used to prepare the

  12. Structural Health Monitoring of a Composite Panel Based on PZT Sensors and a Transfer Impedance Framework.

    Science.gov (United States)

    Dziendzikowski, Michal; Niedbala, Patryk; Kurnyta, Artur; Kowalczyk, Kamil; Dragan, Krzysztof

    2018-05-11

    One of the ideas for development of Structural Health Monitoring (SHM) systems is based on excitation of elastic waves by a network of PZT piezoelectric transducers integrated with the structure. In the paper, a variant of the so-called Transfer Impedance (TI) approach to SHM is followed. Signal characteristics, called the Damage Indices (DIs), were proposed for data presentation and analysis. The idea underlying the definition of DIs was to maintain most of the information carried by the voltage induced on PZT sensors by elastic waves. In particular, the DIs proposed in the paper should be sensitive to all types of damage which can influence the amplitude or the phase of the voltage induced on the sensor. Properties of the proposed DIs were investigated experimentally using a GFRP composite panel equipped with PZT networks attached to its surface and embedded into its internal structure. Repeatability and stability of DI indications under controlled conditions were verified in tests. Also, some performance indicators for surface-attached and structure-embedded sensors were obtained. The DIs' behavior was dependent mostly on the presence of a simulated damage in the structure. Anisotropy of mechanical properties of the specimen, geometrical properties of PZT network as well as, to some extent, the technology of sensor integration with the structure were irrelevant for damage indication. This property enables the method to be used for damage detection and classification.

  13. Tough and strong porous bioactive glass-PLA composites for structural bone repair.

    Science.gov (United States)

    Xiao, Wei; Zaeem, Mohsen Asle; Li, Guangda; Bal, B Sonny; Rahaman, Mohamed N

    2017-08-01

    Bioactive glass scaffolds have been used to heal small contained bone defects but their application to repairing structural bone is limited by concerns about their mechanical reliability. In the present study, the addition of an adherent polymer layer to the external surface of strong porous bioactive glass (13-93) scaffolds was investigated to improve their toughness. Finite element modeling (FEM) of the flexural mechanical response of beams composed of a porous glass and an adherent polymer layer predicted a reduction in the tensile stress in the glass with increasing thickness and elastic modulus of the polymer layer. Mechanical testing of composites with structures similar to the models, formed from 13-93 glass and polylactic acid (PLA), showed trends predicted by the FEM simulations but the observed effects were considerably more dramatic. A PLA layer of thickness -400 µm, equal to -12.5% of the scaffold thickness, increased the load-bearing capacity of the scaffold in four-point bending by ~50%. The work of fracture increased by more than 10,000%, resulting in a non-brittle mechanical response. These bioactive glass-PLA composites, combining bioactivity, high strength, high work of fracture and an internal architecture shown to be conducive to bone infiltration, could provide optimal implants for healing structural bone defects.

  14. Simulation Based Optimization of Complex Monolithic Composite Structures Using Cellular Core Technology

    Science.gov (United States)

    Hickmott, Curtis W.

    Cellular core tooling is a new technology which has the capability to manufacture complex integrated monolithic composite structures. This novel tooling method utilizes thermoplastic cellular cores as inner tooling. The semi-rigid nature of the cellular cores makes them convenient for lay-up, and under autoclave temperature and pressure they soften and expand providing uniform compaction on all surfaces including internal features such as ribs and spar tubes. This process has the capability of developing fully optimized aerospace structures by reducing or eliminating assembly using fasteners or bonded joints. The technology is studied in the context of evaluating its capabilities, advantages, and limitations in developing high quality structures. The complex nature of these parts has led to development of a model using the Finite Element Analysis (FEA) software Abaqus and the plug-in COMPRO Common Component Architecture (CCA) provided by Convergent Manufacturing Technologies. This model utilizes a "virtual autoclave" technique to simulate temperature profiles, resin flow paths, and ultimately deformation from residual stress. A model has been developed simulating the temperature profile during curing of composite parts made with the cellular core technology. While modeling of composites has been performed in the past, this project will look to take this existing knowledge and apply it to this new manufacturing method capable of building more complex parts and develop a model designed specifically for building large, complex components with a high degree of accuracy. The model development has been carried out in conjunction with experimental validation. A double box beam structure was chosen for analysis to determine the effects of the technology on internal ribs and joints. Double box beams were manufactured and sectioned into T-joints for characterization. Mechanical behavior of T-joints was performed using the T-joint pull-off test and compared to traditional

  15. Development of Stitched Composite Structure for Advanced Aircraft

    Science.gov (United States)

    Jegley, Dawn; Przekop, Adam; Rouse, Marshall; Lovejoy, Andrew; Velicki, Alex; Linton, Kim; Wu, Hsi-Yung; Baraja, Jaime; Thrash, Patrick; Hoffman, Krishna

    2015-01-01

    NASA has created the Environmentally Responsible Aviation Project to develop technologies which will reduce the impact of aviation on the environment. A critical aspect of this pursuit is the development of a lighter, more robust airframe that will enable the introduction of unconventional aircraft configurations. NASA and The Boeing Company are working together to develop a structural concept that is lightweight and an advancement beyond state-of-the-art composites. The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is an integrally stiffened panel design where elements are stitched together and designed to maintain residual load-carrying capabilities under a variety of damage scenarios. With the PRSEUS concept, through-the-thickness stitches are applied through dry fabric prior to resin infusion, and replace fasteners throughout each integral panel. Through-the-thickness reinforcement at discontinuities, such as along flange edges, has been shown to suppress delamination and turn cracks, which expands the design space and leads to lighter designs. The pultruded rod provides stiffening away from the more vulnerable skin surface and improves bending stiffness. A series of building blocks were evaluated to explore the fundamental assumptions related to the capability and advantages of PRSEUS panels. These building blocks addressed tension, compression, and pressure loading conditions. The emphasis of the development work has been to assess the loading capability, damage arrestment features, repairability, post-buckling behavior, and response of PRSEUS flat panels to out-of plane pressure loading. The results of this building-block program from coupons through an 80%-scale pressure box have demonstrated the viability of a PRSEUS center body for the Hybrid Wing Body (HWB) transport aircraft. This development program shows that the PRSEUS benefits are also applicable to traditional tube-andwing aircraft, those of advanced configurations, and other

  16. Energy Absorption Capacity in Natural Fiber Reinforcement Composites Structures

    Directory of Open Access Journals (Sweden)

    Elías López-Alba

    2018-03-01

    Full Text Available The study of natural fiber reinforcement composite structures has focused the attention of the automobile industry due to the new regulation in relation to the recyclability and the reusability of the materials preserving and/or improving the mechanical characteristics. The influence of different parameters on the material behavior of natural fiber reinforced plastic structures has been investigated, showing the potential for transport application in energy absorbing structures. Two different woven fabrics (twill and hopsack made of flax fibers as well as a non-woven mat made of a mixture of hemp and kenaf fibers were employed as reinforcing materials. These reinforcing textiles were impregnated with both HD-PE (high-density polyethylen and PLA (polylactic acid matrix, using a continuous compression molding press. The impregnated semi-finished laminates (so-called organic sheets were thermoformed in a second step to half-tubes that were assembled through vibration-welding process to cylindric crash absorbers. The specimens were loaded by compression to determine the specific energy absorption capacity. Quasi-static test results were compared to dynamic test data obtained on a catapult arrangement. The differences on the specific energies absorption (SEA as a function of different parameters, such as the wall thickness, the weave material type, the reinforced textiles, and the matrix used, depending on the velocity rate application were quantified. In the case of quasi-static analysis it is observed a 20% increment in the SEA value when wove Hopsack fabric reinforcement is employed. No velocity rate influence from the material was observed on the SEA evaluation at higher speeds used to perform the experiments. The influence of the weave configuration (Hopsack seems to be more stable against buckling effects at low loading rates with 10% higher SEA values. An increase of SEA level of up to 72% for PLA matrix was observed when compared with HD

  17. Sea urchin vault structure, composition, and differential localization during development

    Directory of Open Access Journals (Sweden)

    Dickey-Sims Carrie

    2005-02-01

    Full Text Available Abstract Background Vaults are intriguing ribonucleoprotein assemblies with an unknown function that are conserved among higher eukaryotes. The Pacific coast sea urchin, Strongylocentrotus purpuratus, is an invertebrate model organism that is evolutionarily closer to humans than Drosophila and C. elegans, neither of which possesses vaults. Here we compare the structures of sea urchin and mammalian vaults and analyze the subcellular distribution of vaults during sea urchin embryogenesis. Results The sequence of the sea urchin major vault protein (MVP was assembled from expressed sequence tags and genome traces, and the predicted protein was found to have 64% identity and 81% similarity to rat MVP. Sea urchin MVP includes seven ~50 residue repeats in the N-terminal half of the protein and a predicted coiled coil domain in the C-terminus, as does rat MVP. A cryoelectron microscopy (cryoEM reconstruction of isolated sea urchin vaults reveals the assembly to have a barrel-shaped external structure that is nearly identical to the rat vault structure. Analysis of the molecular composition of the sea urchin vault indicates that it contains components that may be homologs of the mammalian vault RNA component (vRNA and protein components (VPARP and TEP1. The sea urchin vault appears to have additional protein components in the molecular weight range of 14–55 kDa that might correspond to molecular contents. Confocal experiments indicate a dramatic relocalization of MVP from the cytoplasm to the nucleus during sea urchin embryogenesis. Conclusions These results are suggestive of a role for the vault in delivering macromolecules to the nucleus during development.

  18. Synthesis and structural characterization of polyaniline/cobalt chloride composites

    Energy Technology Data Exchange (ETDEWEB)

    Asha, E-mail: arana5752@gmail.com [Department of Basic and Applied Sciences, Bhagat Phool Singh Mahilla Vishwavidyalaya, Khanpur Kalan, Sonipat-131305 (India); Goyal, Sneh Lata; Kishore, Nawal [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar-125001 (India)

    2016-05-23

    Polyaniline (PANI) and PANI /cobalt chloride composites were synthesized by in situ chemical oxidative polymerization of aniline with CoCl{sub 2}.6H{sub 2}O using ammonium peroxidisulphate as an oxidant. These composites were characterized by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The XRD study reveals that both PANI and composites are amorphous. The XRD and SEM results confirm the presence of cobalt chloride in the composites.

  19. Antimicrobial Carvacrol-Containing Polypropylene Films: Composition, Structure and Function

    Directory of Open Access Journals (Sweden)

    Max Krepker

    2018-01-01

    Full Text Available Significant research has been directed toward the incorporation of bioactive plant extracts or essential oils (EOs into polymers to endow the latter with antimicrobial functionality. EOs offer a unique combination of having broad antimicrobial activity from a natural source, generally recognized as safe (GRAS recognition in the US, and a volatile nature. However, their volatility also presents a major challenge in their incorporation into polymers by conventional high-temperature-processing techniques. Herein, antimicrobial polypropylene (PP cast films were produced by incorporating carvacrol (a model EO or carvacrol, loaded into halloysite nanotubes (HNTs, via melt compounding. We studied the composition-structure-property relationships in these systems, focusing on the effect of carvacrol on the composition of the films, the PP crystalline phase and its morphology and the films’ mechanical and antimicrobial properties. For the first time, molecular dynamics simulations were applied to reveal the complex interactions between the components of these carvacrol-containing systems. We show that strong molecular interactions between PP and carvacrol minimize the loss of this highly-volatile EO during high-temperature polymer processing, enabling semi-industrial scale production. The resulting films exhibit outstanding antimicrobial properties against model microorganisms (Escherichia coli and Alternaria alternata. The PP/(HNTs-carvacrol nanocomposite films, containing the carvacrol-loaded HNTs, display a higher level of crystalline order, superior mechanical properties and prolonged release of carvacrol, in comparison to PP/carvacrol blends. These properties are ascribed to the role of HNTs in these nanocomposites and their effect on the PP matrix and retained carvacrol content.

  20. 77 FR 50576 - Damage Tolerance and Fatigue Evaluation of Composite Rotorcraft Structures; OMB Approval of...

    Science.gov (United States)

    2012-08-22

    ... Composite Rotorcraft Structures; OMB Approval of Information Collection AGENCY: Federal Aviation... Rotorcraft Structures,'' which was published on December 1, 2011. DATES: The rule published on December 1... and Fatigue Evaluation of Composite Rotorcraft Structures,'' published in the Federal Register (76 FR...

  1. 77 FR 4890 - Damage Tolerance and Fatigue Evaluation for Composite Rotorcraft Structures, and Damage Tolerance...

    Science.gov (United States)

    2012-02-01

    ...-AJ52, 2120-AJ51 Damage Tolerance and Fatigue Evaluation for Composite Rotorcraft Structures, and Damage Tolerance and Fatigue Evaluation for Metallic Structures; Correction AGENCY: Federal Aviation Administration... Tolerance and Fatigue Evaluation for Composite Rotorcraft Structures'' (76 FR 74655), published December 1...

  2. Molecular Diagnostics of the Internal Structure of Starspots and Sunspots

    Science.gov (United States)

    Afram, N.; Berdyugina, S. V.; Fluri, D. M.; Solanki, S. K.; Lagg, A.; Petit, P.; Arnaud, J.

    2006-12-01

    We have analyzed the usefulness of molecules as a diagnostic tool for studying solar and stellar magnetism with the molecular Zeeman and Paschen-Back effects. In the first part we concentrate on molecules that are observed in sunspots such as MgH and TiO. We present calculated molecular line profiles obtained by assuming magnetic fields of 2-3 kG and compare these synthetic Stokes profiles with spectro-polarimetric observations in sunspots. The good agreement between the theory and observations allows us to turn our attention in the second part to starspots to gain insight into their internal structure. We investigate the temperature range in which the selected molecules can serve as indicators for magnetic fields on highly active cool stars and compare synthetic Stokes profiles with our recent observations.

  3. Nonlocal transformation of the internal quantum particle structure

    Directory of Open Access Journals (Sweden)

    Alexey Yu. Samarin

    2016-09-01

    Full Text Available The analysis of the integral wave equation, having path integral kernel, has resulted, that collapse phenomenon is based on the nonlocal transformation of the internal structure of a quantum particle, considering in the form of the matter fields collection. This nonlocality allows to escape the contradiction between the reduction quantum mechanics postulate and special relativity. It is shown, that the wave function transformation, corresponding to von Neumann's reduction, has the deterministic nature and the quantum mechanics stochasticity is a consequence of a macroscopic measurer presence in the measuring process. Besides it is demonstrated, that the decogerence phenomenon has the same mechanism of the wave function transformation. EPR-type experiment is described in detail and the possibility of the faster-then light communication is proved, as well the possible rules of thumb of this communication are proposed.

  4. A proposed structure for an international convention on climate change

    International Nuclear Information System (INIS)

    Nitze, W.A.

    1991-01-01

    In this chapter, the author recommends a framework convention that will stimulate policy changes without expensive emission reductions in the short term. A central task for a climate convention will be to provide the international community with a permanent mechanism for coordinating its efforts to deal with climate change. The convention should go beyond organizational structure to establish a process for updating the parties' understanding of the science and potential impacts of climate change and for building consensus on policy responses. Each party must then be required to prepare and distribute its own national plan for reducing greenhouse gas emissions and for adapting to future change while achieving its development objectives. A set of targets and timetables for the reduction of greenhouse gas reductions is presented

  5. Imaging Internal Structure of Long Bones Using Wave Scattering Theory.

    Science.gov (United States)

    Zheng, Rui; Le, Lawrence H; Sacchi, Mauricio D; Lou, Edmond

    2015-11-01

    An ultrasonic wavefield imaging method is developed to reconstruct the internal geometric properties of long bones using zero-offset data acquired axially on the bone surface. The imaging algorithm based on Born scattering theory is implemented with the conjugate gradient iterative method to reconstruct an optimal image. In the case of a multilayered velocity model, ray tracing through a smooth medium is used to calculate the traveled distance and traveling time. The method has been applied to simulated and real data. The results indicate that the interfaces of the top cortex are accurately imaged and correspond favorably to the original model. The reconstructed bottom cortex below the marrow is less accurate mainly because of the low signal-to-noise ratio. The current imaging method has successfully recovered the top cortical layer, providing a potential tool to investigate the internal structures of long bone cortex for osteoporosis assessment. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  6. Structural, chemical and electrical characterisation of conductive graphene-polymer composite films

    Energy Technology Data Exchange (ETDEWEB)

    Brennan, Barry; Spencer, Steve J.; Belsey, Natalie A. [National Physical Laboratory, Teddington, TW11 0LW (United Kingdom); Faris, Tsegie [DZP Technologies Ltd., Future Business Centre, Cambridge, CB4 2HY (United Kingdom); Cronin, Harry [DZP Technologies Ltd., Future Business Centre, Cambridge, CB4 2HY (United Kingdom); Advanced Technology Institute (ATI), University of Surrey, Guildford, GU2 7XH (United Kingdom); Silva, S. Ravi P. [Advanced Technology Institute (ATI), University of Surrey, Guildford, GU2 7XH (United Kingdom); Sainsbury, Toby; Gilmore, Ian S. [National Physical Laboratory, Teddington, TW11 0LW (United Kingdom); Stoeva, Zlatka [DZP Technologies Ltd., Future Business Centre, Cambridge, CB4 2HY (United Kingdom); Pollard, Andrew J., E-mail: andrew.pollard@npl.co.uk [National Physical Laboratory, Teddington, TW11 0LW (United Kingdom)

    2017-05-01

    Graphical abstract: Secondary Ion Mass Spectrometry (SIMS) imaging of the dispersion of graphene within graphene-polymer composites using the Na{sup +} signal. - Highlights: • Relation of properties of graphene flakes with electrical properties of composite. • Standardised characterisation method for structural properties of graphene flakes. • Structural and chemical characterisation of commercial graphene flakes. • ToF-SIMS used to determine dispersion of graphene in polymer. - Abstract: Graphene poly-acrylic and PEDOT:PSS nanocomposite films were produced using two alternative commercial graphene powders to explore how the graphene flake dimensions and chemical composition affected the electrical performance of the film. A range of analytical techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), were employed to systematically analyse the initial graphene materials as well as the nanocomposite films. Electrical measurements indicated that the sheet resistance of the films was affected by the properties of the graphene flakes used. To further explore the composition of the films, ToF-SIMS mapping was employed and provided a direct means to elucidate the nature of the graphene dispersion in the films and to correlate this with the electrical analysis. These results reveal important implications for how the dispersion of the graphene material in films produced from printable inks can be affected by the type of graphene powder used and the corresponding effect on electrical performance of the nanocomposites. This work provides direct evidence for how accurate and comparable characterisation of the graphene material is required for real-world graphene materials to develop graphene enabled films and proposes a measurement protocol for comparing graphene materials that can be used for international

  7. Fibre reinforced composites '84; Proceedings of the International Conference, University of Liverpool, England, April 3-5, 1984

    Energy Technology Data Exchange (ETDEWEB)

    1984-01-01

    Among the topics discussed are phenolic resin matrix composites for high temperature and fire-exposure applications, novel resins for fiber-reinforced composite productivity improvement, the use of engineering textiles for mechanical property improvement in composites, the significance of aramid fiber reinforcement in composites, the energy absorption properties of Sheet Metal Compounds (SMCs) under crash conditions, and SMC impact behavior variations with temperature. Also covered are CFRP applications in high performance structures, composite helicopter main rotor blade technology, composite vehicular leaf springs, carbon fiber-reinforced thermoplastics, filament winding development status, the injection processing of fiber-reinforced thermoplastics, civil aircraft composite structure certification, composite radomes, design procedures for short fiber-reinforced thermoplastics, the strength limitations of mechanically fastened lap joints, environmental fatigue and creep in glass-reinforced materials, the effects of moisture on high performance laminates, the environmental behavior of SMC, and corrugated composites.

  8. FIBER-TEX 1991: The Fifth Conference on Advanced Engineering Fibers and Textile Structures for Composites

    International Nuclear Information System (INIS)

    Buckley, J.D.

    1992-10-01

    This document is a compilation of papers presented at a joint NASA/North Carolina State University/DoD/Clemson University/Drexel University conference on Fibers, Textile Technology, and Composites Structures held at the College of Textiles Building on Centennial Campus of North Carolina State University, Raleigh, North Carolina on October 15-17, 1991. Conference papers presented information on advanced engineering fibers, textile processes and structures, structural fabric production, mechanics and characteristics of woven composites, pultruded composites, and the latest requirements for the use of textiles in the production of composite materials and structures. Separate abstracts have been prepared for papers in this report

  9. A multiscale MD-FE model of diffusion in composite media with internal surface interaction based on numerical homogenization procedure.

    Science.gov (United States)

    Kojic, M; Milosevic, M; Kojic, N; Kim, K; Ferrari, M; Ziemys, A

    2014-02-01

    Mass transport by diffusion within composite materials may depend not only on internal microstructural geometry, but also on the chemical interactions between the transported substance and the material of the microstructure. Retrospectively, there is a gap in methods and theory to connect material microstructure properties with macroscale continuum diffusion characteristics. Here we present a new hierarchical multiscale model for diffusion within composite materials that couples material microstructural geometry and interactions between diffusing particles and the material matrix. This model, which bridges molecular dynamics (MD) and the finite element (FE) method, is employed to construct a continuum diffusion model based on a novel numerical homogenization procedure. The procedure is general and robust for evaluating constitutive material parameters of the continuum model. These parameters include the traditional bulk diffusion coefficients and, additionally, the distances from the solid surface accounting for surface interaction effects. We implemented our models to glucose diffusion through the following two geometrical/material configurations: tightly packed silica nanospheres, and a complex fibrous structure surrounding nanospheres. Then, rhodamine 6G diffusion analysis through an aga-rose gel network was performed, followed by a model validation using our experimental results. The microstructural model, numerical homogenization and continuum model offer a new platform for modeling and predicting mass diffusion through complex biological environment and within composite materials that are used in a wide range of applications, like drug delivery and nanoporous catalysts.

  10. A multiscale MD–FE model of diffusion in composite media with internal surface interaction based on numerical homogenization procedure

    Science.gov (United States)

    Kojic, M.; Milosevic, M.; Kojic, N.; Kim, K.; Ferrari, M.; Ziemys, A.

    2014-01-01

    Mass transport by diffusion within composite materials may depend not only on internal microstructural geometry, but also on the chemical interactions between the transported substance and the material of the microstructure. Retrospectively, there is a gap in methods and theory to connect material microstructure properties with macroscale continuum diffusion characteristics. Here we present a new hierarchical multiscale model for diffusion within composite materials that couples material microstructural geometry and interactions between diffusing particles and the material matrix. This model, which bridges molecular dynamics (MD) and the finite element (FE) method, is employed to construct a continuum diffusion model based on a novel numerical homogenization procedure. The procedure is general and robust for evaluating constitutive material parameters of the continuum model. These parameters include the traditional bulk diffusion coefficients and, additionally, the distances from the solid surface accounting for surface interaction effects. We implemented our models to glucose diffusion through the following two geometrical/material configurations: tightly packed silica nanospheres, and a complex fibrous structure surrounding nanospheres. Then, rhodamine 6G diffusion analysis through an aga-rose gel network was performed, followed by a model validation using our experimental results. The microstructural model, numerical homogenization and continuum model offer a new platform for modeling and predicting mass diffusion through complex biological environment and within composite materials that are used in a wide range of applications, like drug delivery and nanoporous catalysts. PMID:24578582

  11. Internal structure and swelling behaviour of in silico microgel particles

    Science.gov (United States)

    Rovigatti, Lorenzo; Gnan, Nicoletta; Zaccarelli, Emanuela

    2018-01-01

    Microgels are soft colloids that, by virtue of their polymeric nature, can react to external stimuli such as temperature or pH by changing their size. The resulting swelling/deswelling transition can be exploited in fundamental research as well as for many diverse practical applications, ranging from art restoration to medicine. Such an extraordinary versatility stems from the complex internal structure of the individual microgels, each of which is a crosslinked polymer network. Here we employ a recently-introduced computational method to generate realistic microgel configurations and look at their structural properties, both in real and Fourier space, for several temperatures across the volume phase transition as a function of the crosslinker concentration and of the confining radius employed during the ‘in-silico’ synthesis. We find that the chain-length distribution of the resulting networks can be analytically predicted by a simple theoretical argument. In addition, we find that our results are well-fitted to the fuzzy-sphere model, which correctly reproduces the density profile of the microgels under study.

  12. The Okhansk Meteorite: Specifics of Composition, Structure, and Genesis

    Directory of Open Access Journals (Sweden)

    A.I. Bakhtin

    2016-12-01

    Full Text Available The Okhansk meteorite fell on August 18, 1887 near the village of Tabor, about 15 km away from the town of Okhansk in Perm province and weighed 186.5 kg (the total weight of collected fragments, according to P.I. Krotov, was more than 245 kg. The shock wave from the meteorite entry knocked down animals and riders on horses. Despite the fact that it was significantly stronger than that caused by the Chelyabinsk meteorite of 2013, all information about this meteorite has completely erased from people's memory. It has been shown that the meteorite is an ordinary olivine-bronzite chondrite. Its main silicate minerals are olivine, bronzite, plagioclase, and diopside. The main ore minerals are kamacite and troilite. The meteorite contains silicate glass in large amounts. The analysis of the composition and structure of the Okhansk meteorite has demonstrated that it was formed at the early stages of accretion of the melted substance of the protosolar nebula without undergoing endogenous, temperature, or pressure changes.

  13. Composite Polymer Electrolytes: Nanoparticles Affect Structure and Properties

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2016-11-01

    Full Text Available Composite polymer electrolytes (CPEs can significantly improve the performance in electrochemical devices such as lithium-ion batteries. This review summarizes property/performance relationships in the case where nanoparticles are introduced to polymer electrolytes. It is the aim of this review to provide a knowledge network that elucidates the role of nano-additives in the CPEs. Central to the discussion is the impact on the CPE performance of properties such as crystalline/amorphous structure, dielectric behavior, and interactions within the CPE. The amorphous domains of semi-crystalline polymer facilitate the ion transport, while an enhanced mobility of polymer chains contributes to high ionic conductivity. Dielectric properties reflect the relaxation behavior of polymer chains as an important factor in ion conduction. Further, the dielectric constant (ε determines the capability of the polymer to dissolve salt. The atom/ion/nanoparticle interactions within CPEs suggest ways to enhance the CPE conductivity by generating more free lithium ions. Certain properties can be improved simultaneously by nanoparticle addition in order to optimize the overall performance of the electrolyte. The effects of nano-additives on thermal and mechanical properties of CPEs are also presented in order to evaluate the electrolyte competence for lithium-ion battery applications.

  14. Background and perspective on rapid progress and deepening of international development of nuclear industry-composition of international nuclear energy business 'cooperation and competition'

    International Nuclear Information System (INIS)

    Kano, Tokio; Kanda, Keji; Ishizuka, Nobuo

    2005-01-01

    Based on the recognition that international development of nuclear industry was important by a viewpoint of international cooperation to neighboring Asian area and also it was the trump that defeated a feeling of domestic confinement, the Japan Atomic Industrial Forum (JAIF) founded Nuclear energy international development gathering' in November 2004. On that occasion our magazine (March, 2005 issue) featured 'prospects and problem of the international development of nuclear energy use'. Slightly for half a year afterwards this nuclear energy international development has been rapidly deepened and become a close-up as a policy of an important strategy of the field of nuclear energy that the government and the private sector were united to make. Therefore the nuclear energy international development was secondly featured from multidirectional points of view such as a background of nuclear energy international development, composition of international nuclear energy business, a main strategy of three makers, approach of finance / a business firm. (T. Tanaka)

  15. Smoke composition and predicting relationships for international commercial cigarettes smoked with three machine-smoking conditions.

    Science.gov (United States)

    Counts, M E; Morton, M J; Laffoon, S W; Cox, R H; Lipowicz, P J

    2005-04-01

    The study objectives were to determine the effects of smoking machine puffing parameters on mainstream smoke composition and to express those effects as predicting relationships. Forty-eight commercial Philip Morris USA and Philip Morris International cigarettes from international markets and the 1R4F reference cigarette were machine-smoked using smoking conditions defined by the International Organization of Standardization (ISO), the Massachusetts Department of Public Health (MDPH), and Health Canada (HC). Cigarette tobacco fillers were analyzed for nitrate, nicotine, tobacco-specific nitrosamines (TSNA), and ammonia. Mainstream yields for tar and 44 individual smoke constituents and "smoke pH" were determined. Cigarette constituent yields typically increased in the order ISOrelationships were developed between ISO tar and ISO, MDPH, and HC constituent yields and between MDPH tar and HC tar and respective smoking condition yields. MDPH and HC constituent yields could be predicted with similar reliability using ISO tar or the corresponding smoking-condition tar. The reliability of the relationships varied from strong to weak, depending on particular constituents. Weak predicting relationships for nitrogen oxides and TSNA's, for example, were improved with inclusion of tobacco filler composition factors. "Smoke pH" was similar for all cigarettes at any one smoking condition, and overall marginally lower at HC conditions than at ISO or MDPH conditions.

  16. Structural and compositional analysis of a casting mold sherd from ancient China.

    Science.gov (United States)

    Zong, Yunbing; Yao, Shengkun; Lang, Jianfeng; Chen, Xuexiang; Fan, Jiadong; Sun, Zhibin; Duan, Xiulan; Li, Nannan; Fang, Hui; Zhou, Guangzhao; Xiao, Tiqiao; Li, Aiguo; Jiang, Huaidong

    2017-01-01

    Casting had symbolic significance and was strictly controlled in the Shang dynasty of ancient China. Vessel casting was mainly distributed around the Shang capital, Yin Ruins, which indicates a rigorous centralization of authority. Thus, for a casting mold to be excavated far from the capital region is rare. In addition to some bronze vessel molds excavated at the Buyao Village site, another key discovery of a bronze vessel mold occurred at Daxinzhuang. The Daxinzhuang site was a core area in the east of Shang state and is an important site to study the eastward expansion of the Shang. Here, combining synchrotron X-rays and other physicochemical analysis methods, nondestructive three-dimensional structure imaging and different elemental analyses were conducted on this mold sherd. Through high penetration X-ray tomography, we obtained insights on the internal structure and discovered some pores. We infer that the generation of pores inside the casting mold sherd was used to enhance air permeability during casting. Furthermore, we suppose that the decorative patterns on the surface were carved and not pasted onto it. Considering the previous compositional studies of bronze vessels, the copper and iron elements were analyzed by different methods. Unexpectedly, a larger amount of iron than of copper was detected on the surface. According to the data analysis and archaeological context, the source of iron on the casting mold sherd could be attributed to local soil contamination. A refined compositional analysis confirms that this casting mold was fabricated locally and used for bronze casting.

  17. Structural and thermophysical properties characterization of continuously reinforced cast Al matrix composite

    Directory of Open Access Journals (Sweden)

    Brian Gordon

    2010-11-01

    Full Text Available In this work the process of manufacturing a continuously reinforced cast Al matrix composite and its properties are presented. The described technology permits obtaining a structural material of competitive properties compared to either heat treatable aluminum alloys or polymer composites for several types of applications. The examined thermophysical properties and structural characterization, including material anisotropy, coupled with the results of previous measurements of the mechanical properties of both Al2O3 reinforcing filaments and metallic prepregs have proven the high quality of this material and the possibility of its operation under special loading modes and environmental conditions. Microscopic examinations (LM, SEM were carried out to reveal the range of morphological homogeneity of the microstructure, the anisotropy of the filament band distribution, and simultaneously the adhesive behavior of the metal/fiber interface. The 3D morphology of the chosen microstructure components was revealed by computed tomography. The obtained results indicate that special properties of the examined prepreg materials have been strongly influenced, on the one hand, by the geometry of its internal microstructure, i.e. spatial distribution and volume fraction of the Al2O3 reinforcing filaments and, on the other hand, by a very good compatibility obtained between the individual metal prepreg components.

  18. Correspondence Analysis of Soil around Micropile Composite Structures under Horizontal Load

    Directory of Open Access Journals (Sweden)

    Hai Shi

    2015-01-01

    Full Text Available The current approach, which is based on conformal transformation, is to map micropile holes in comparison with unit circle domain. The stress field of soil around a pile plane, as well as the plane strain solution to displacement field distribution, can be obtained by adopting complex variable functions of elastic mechanics. This paper proposes an approach based on Winkler Foundation Beam Model, with the assumption that the soil around the micropiles stemmed from a series of independent springs. The rigidity coefficient of the springs is to be obtained from the planar solution. Based on the deflection curve differential equation of Euler-Bernoulli beams, one can derive the pile deformation and internal force calculation method of micropile composite structures under horizontal load. In the end, we propose reinforcing highway landslides with micropile composite structure and conducting on-site pile pushing tests. The obtained results from the experiment were then compared with the theoretical approach. It has been indicated through validation analysis that the results obtained from the established theoretical approach display a reasonable degree of accuracy and reliability.

  19. Structural and compositional analysis of a casting mold sherd from ancient China.

    Directory of Open Access Journals (Sweden)

    Yunbing Zong

    Full Text Available Casting had symbolic significance and was strictly controlled in the Shang dynasty of ancient China. Vessel casting was mainly distributed around the Shang capital, Yin Ruins, which indicates a rigorous centralization of authority. Thus, for a casting mold to be excavated far from the capital region is rare. In addition to some bronze vessel molds excavated at the Buyao Village site, another key discovery of a bronze vessel mold occurred at Daxinzhuang. The Daxinzhuang site was a core area in the east of Shang state and is an important site to study the eastward expansion of the Shang. Here, combining synchrotron X-rays and other physicochemical analysis methods, nondestructive three-dimensional structure imaging and different elemental analyses were conducted on this mold sherd. Through high penetration X-ray tomography, we obtained insights on the internal structure and discovered some pores. We infer that the generation of pores inside the casting mold sherd was used to enhance air permeability during casting. Furthermore, we suppose that the decorative patterns on the surface were carved and not pasted onto it. Considering the previous compositional studies of bronze vessels, the copper and iron elements were analyzed by different methods. Unexpectedly, a larger amount of iron than of copper was detected on the surface. According to the data analysis and archaeological context, the source of iron on the casting mold sherd could be attributed to local soil contamination. A refined compositional analysis confirms that this casting mold was fabricated locally and used for bronze casting.

  20. Structure and properties of pregelatinized cassava starch/kaolin composites

    International Nuclear Information System (INIS)

    Kaewtatip, Kaewta; Tanrattanakul, Varaporn

    2012-01-01

    Highlights: ► Pregelatinized starch/kaolin composites were prepared using compression molding. ► The tensile strengths of the composites were higher than for thermoplastic starch. ► Degradation temperatures of the composites were higher than for thermoplastic starch. ► The retrogradation behavior of the composites was hindered by kaolin. -- Abstract: Pregelatinized cassava starch/kaolin composites were prepared using compression molding. The morphology of the fractured surfaces, retrogradation behavior, thermal decomposition temperatures and mechanical properties of the composites were investigated using scanning election microscopy (SEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA) and tensile testing, respectively. The tensile strengths and thermal degradation temperatures of the composites were higher than for thermoplastic starch (TPS). The retrogradation behavior of the composites was hindered by kaolin. The water absorption was measured after aging for 12 and 45 days at a relative humidity (RH) of 15% and 55%. It indicated that all the composites displayed lower water absorption values than TPS.

  1. Saturn's Internal Structure: A View through its Natural Seismograph

    Science.gov (United States)

    Mankovich, Christopher; Marley, Mark S.; Fortney, Jonathan J.; Movshovitz, Naor

    2017-10-01

    Saturn's nonradial oscillations perturb the orbits of ring particles. The C ring is fortuitous in that it spans several resonances with Saturn's fundamental acoustic (f-) modes, and its moderate optical depth allows the characterization of wave features using stellar occultations. The growing set of C-ring waves with precise pattern frequencies and azimuthal order m measured from Cassini stellar occultations (Hedman & Nicholson 2013, 2014; French et al. 2016) provides new constraints on Saturn's internal structure, with the potential to resolve long-standing questions about the planet's distribution of helium and heavier elements, its means of internal energy transport, and its rotation state.We construct Saturn interior models and calculate mode eigenfrequencies, mapping the planet mode frequencies to resonant locations in the rings to compare with the locations of observed spiral density and vertical bending waves in the C ring. While spiral density waves at low azimuthal order (m=2-3) appear strongly affected by resonant coupling between f-modes and deep g-modes (Fuller 2014), the locations of waves with higher azimuthal order can be fit reasonably well with a spectrum of pure f-modes for Saturn models with adiabatic envelopes and realistic equations of state. In particular, four observed bending waves (Nicholson et al., DPS 2016) align with outer vertical resonances for non-sectoral (m≠l) Saturn f-modes of relatively high angular degree, and we present preliminary identifications of these. We assess the range of resonance locations in the C and D rings allowed for the spectrum of f-modes given gravity field constraints and discuss what role a realistic helium distribution in the planet might play.

  2. Advanced composites structural concepts and materials technologies for primary aircraft structures: Design/manufacturing concept assessment

    Science.gov (United States)

    Chu, Robert L.; Bayha, Tom D.; Davis, HU; Ingram, J. ED; Shukla, Jay G.

    1992-01-01

    Composite Wing and Fuselage Structural Design/Manufacturing Concepts have been developed and evaluated. Trade studies were performed to determine how well the concepts satisfy the program goals of 25 percent cost savings, 40 percent weight savings with aircraft resizing, and 50 percent part count reduction as compared to the aluminum Lockheed L-1011 baseline. The concepts developed using emerging technologies such as large scale resin transfer molding (RTM), automatic tow placed (ATP), braiding, out-of-autoclave and automated manufacturing processes for both thermoset and thermoplastic materials were evaluated for possible application in the design concepts. Trade studies were used to determine which concepts carry into the detailed design development subtask.

  3. Application of Ultrasonic Phased Array Technology to the Detection of Defect in Composite Stiffened-structures

    Science.gov (United States)

    Zhou, Yuan-Qi; Zhan, Li-Hua

    2016-05-01

    Composite stiffened-structure consists of the skin and stringer has been widely used in aircraft fuselage and wings. The main purpose of the article is to detect the composite material reinforced structure accurately and explore the relationship between defect formation and structural elements or curing process. Based on ultrasonic phased array inspection technology, the regularity of defects in the manufacture of composite materials are obtained, the correlation model between actual defects and nondestructive testing are established. The article find that the forming quality of deltoid area in T-stiffened structure is obviously improved by pre-curing, the defects of hat-stiffened structure are affected by the mandrel. The results show that the ultrasonic phased array inspection technology can be an effectively way for the detection of composite stiffened-structures, which become an important means to control the defects of composite and improve the quality of the product.

  4. Nonlinear Dynamic Behavior of Impact Damage in a Composite Skin-Stiffener Structure

    Science.gov (United States)

    Ooijevaar, T. H.; Rogge, M. D.; Loendersloot, R.; Warnet, L.; Akkerman, R.; deBoer, A.

    2013-01-01

    One of the key issues in composite structures for aircraft applications is the early identification of damage. Often, service induced damage does not involve visible plastic deformation, but internal matrix related damage, like delaminations. A wide range of technologies, comprising global vibration and local wave propagation methods can be employed for health monitoring purposes. Traditional low frequency modal analysis based methods are linear methods. The effectiveness of these methods is often limited since they rely on a stationary and linear approximation of the system. The nonlinear interaction between a low frequency wave field and a local impact induced skin-stiffener failure is experimentally demonstrated in this paper. The different mechanisms that are responsible for the nonlinearities (opening, closing and contact) of the distorted harmonic waveforms are separated with the help of phase portraits. A basic analytical model is employed to support the observations.

  5. A Nanostructured Composites Thermal Switch Controls Internal and External Short Circuit in Lithium Ion Batteries

    Science.gov (United States)

    McDonald, Robert C.; VanBlarcom, Shelly L.; Kwasnik, Katherine E.

    2013-01-01

    A document discusses a thin layer of composite material, made from nano scale particles of nickel and Teflon, placed within a battery cell as a layer within the anode and/or the cathode. There it conducts electrons at room temperature, then switches to an insulator at an elevated temperature to prevent thermal runaway caused by internal short circuits. The material layer controls excess currents from metal-to-metal or metal-to-carbon shorts that might result from cell crush or a manufacturing defect

  6. Carbon Fiber Reinforced Carbon Composites Rotary Valves for Internal Combustion Engines

    Science.gov (United States)

    Northam, G. Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

    1999-01-01

    Carbon fiber reinforced carbon composite rotary, sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or warp-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties, do not present the sealing and lubrication problems that have prevented rotary, sleeve, and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  7. Carbon Fiber Reinforced Carbon Composite Rotary Valve for an Internal Combustion Engine

    Science.gov (United States)

    Northam, G.Burton (Inventor); Ransone, Philip O. (Inventor); Rivers, H. Kevin (Inventor)

    2000-01-01

    Carbon fiber reinforced carbon composite rotary sleeve, and disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or wrap-locked carbon fiber shapes. Also disclosed are valves fabricated from woven carbon fibers and from molded carbon matrix material. The valves of the present invention with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties do not present the sealing and lubrication problems that have prevented rotary sleeve and disc valves from operating efficiently and reliably in the past. Also disclosed are a sealing tang to further improve sealing capabilities and anti-oxidation treatments.

  8. Structural Analysis of Ciprofloxacin-Carbopol Polymeric Composites ...

    African Journals Online (AJOL)

    Purpose: To evaluate physicochemical changes in ciprofloxacin following incorporation in Carbopol polymeric composites. Methods: The ciprofloxacin and Carbopol were mixed in water in a drug:polymer ratio of 1:5 (w/w) and homogenized to produce uniform composites. X-ray powder diffraction analysis of the pure ...

  9. Simulating Dynamic Vehicle Maneuvers Using Finite Elements For Use In Design Of Integrated Composite Structure

    OpenAIRE

    Angelini, Nicholas Alexander

    2014-01-01

    Formula SAE (FSAE) chassis systems are increasing being manufactured with integrated composite structures in an effort to increase the performance of the system while decreasing weight. The increased use of composite structures requires more details of the loading conditions and evaluation metrics than the mild steel structures they are replacing. The prototypical FSAE steel space frame chassis designs are heavily structured around the mandated safety rules that doubled as mostly satisfactory...

  10. Mechanical Properties Of 3D-Structure Composites Based On Warp-Knitted Spacer Fabrics

    Directory of Open Access Journals (Sweden)

    Chen Si

    2015-06-01

    Full Text Available In this paper, the mechanical properties (compression and impact behaviours of three-dimension structure (3D-structure composites based on warp-knitted spacer fabrics have been thoroughly investigated. In order to discuss the effect of fabric structural parameters on the mechanical performance of composites, six different types of warp-knitted spacer fabrics having different structural parameters (such as outer layer structure, diameter of spacer yarn, spacer yarn inclination angle and thickness were involved for comparison study. The 3D-structure composites were fabricated based on a flexible polyurethane foam. The produced composites were characterised for compression and impact properties. The findings obtained indicate that the fabric structural parameters have strong influence on the compression and impact responses of 3D-structure composites. Additionally, the impact test carried out on the 3D-structure composites shows that the impact loads do not affect the integrity of composite structure. All the results reveal that the product exhibits promising mechanical performance and its service life can be sustained.

  11. Penetration effect in internal conversion and nuclear structure

    International Nuclear Information System (INIS)

    Listengarten, M.A.

    1978-01-01

    The conditions for the appearance of the anomalous internal conversion coefficients (ICC) are considered, when the contribution of the penetration matrix element (PME) is of the order of or larger than the main part of the conversion matrix element. The experimental magnitudes of the nuclear PME agree well with those calculated in the framework of simple nuclear models, provided the magnitude of PME is not decreased due to the model -dependent selection rules. The magnitude of the anomaly ( lanbda parameter ) is compared with the exclusion factor of γ-transition relative to the Weisskopf estimation. The better is the model of the nucleus the weaker is the dependence of the lambda magnitude on the exclusion factor. ICC coefficients might be anomalous for those γ-transitions for which the exclusion factor calculated in the framework of more rigorous model are of the order of unity. In the ''ideal'' model of nucleus completely adequate to the true nuclear structure the dependence of the lambda penetration parameter on the exclusion factor vanishes

  12. Eighth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design, part 2

    Energy Technology Data Exchange (ETDEWEB)

    Starnes, J.H. Jr.; Bohon, H.L.; Garzon, S.B.

    1990-09-01

    Papers presented at the conference are compiled. The conference provided a forum for the scientific community to exchange composite structures design information and an opportunity to observe recent progress in composite structures design and technology. Part 2 contains papers related to the following subject areas: the application in design; methodology in design; and reliability in design.

  13. Eighth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design, Part 2

    Science.gov (United States)

    Starnes, James H., Jr. (Compiler); Bohon, Herman L. (Compiler); Garzon, Sherry B. (Compiler)

    1990-01-01

    Papers presented at the conference are compiled. The conference provided a forum for the scientific community to exchange composite structures design information and an opportunity to observe recent progress in composite structures design and technology. Part 2 contains papers related to the following subject areas: the application in design; methodology in design; and reliability in design.

  14. Using thin metal layers on composite structures for shielding the electromagnetic pulse caused by nearby lightning

    NARCIS (Netherlands)

    Blaj, M.A.; Buesink, Frederik Johannes Karel; Damstra, G.C.; Leferink, Frank Bernardus Johannes

    2011-01-01

    Electronic systems in composite structures could be vulnerable to the (dominant magnetic) field caused by a lightning strike, because only thin layers of metal can be used on composite structures. Thin layers result in a very low shielding effectiveness against magnetic fields. Many experiments

  15. Lightning current tests to evaluate vulnerability of electronics in composite structures

    NARCIS (Netherlands)

    Blaj, M.A.; Buesink, Frederik Johannes Karel; Damstra, G.C.; Leferink, Frank Bernardus Johannes

    2010-01-01

    Protecting highly sensitive electronics housed inside composite structures against lightning is a real challenge. The direct strike represents the worst-case scenario for composite structures. The electromagnetic field generated by an indirect lightning strike in the vicinity of highly sensitive

  16. Structure and composition of woody vegetation in two important bird areas in southern Zimbabwe

    NARCIS (Netherlands)

    Gandiwa, P.; Chinoitezvi, E.; Gandiwa, E.

    2013-01-01

    This study assessed the status of woody vegetation structure and composition in two Important Bird Areas (IBA) i.e. Manjinji Pan and Save-Runde Junction located in southeastern Zimbabwe. The objectives of this study were to: (i) determine the woody vegetation structure and composition of the study

  17. Bioinspired engineering study of Plantae vascules for self-healing composite structures

    Science.gov (United States)

    Trask, R. S.; Bond, I. P.

    2010-01-01

    This paper presents the first conceptual study into creating a Plantae-inspired vascular network within a fibre-reinforced polymer composite laminate, which provides an ongoing self-healing functionality without incurring a mass penalty. Through the application of a ‘lost-wax’ technique, orthogonal hollow vascules, inspired by the ‘ray cell’ structures found in ring porous hardwoods, were successfully introduced within a carbon fibre-reinforced epoxy polymer composite laminate. The influence on fibre architecture and mechanical behaviour of single vascules (located on the laminate centreline) when aligned parallel and transverse to the local host ply was characterized experimentally using a compression-after-impact test methodology. Ultrasonic C-scanning and high-resolution micro-CT X-ray was undertaken to identify the influence of and interaction between the internal vasculature and impact damage. The results clearly show that damage morphology is influenced by vascule orientation and that a 10 J low-velocity impact damage event is sufficient to breach the vasculature; a prerequisite for any subsequent self-healing function. The residual compressive strength after a 10 J impact was found to be dependent upon vascule orientation. In general, residual compressive strength decreased to 70 per cent of undamaged strength when vasculature was aligned parallel to the local host ply and a value of 63 per cent when aligned transverse. This bioinspired engineering study has illustrated the potential that a vasculature concept has to offer in terms of providing a self-healing function with minimum mass penalty, without initiating premature failure within a composite structure. PMID:19955122

  18. Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design, volume 3

    Energy Technology Data Exchange (ETDEWEB)

    Soderquist, J.R.; Neri, L.M.; Bohon, H.L.

    1992-09-01

    This publication contains the proceedings of the Ninth DOD/NASA/FAA Conference on Fibrous Composites in Structural Design held at Lake Tahoe, Nevada, during 4-7 Nov. 1991. Presentations were made in the following areas of composite structural design: perspectives in composites, design methodology, design applications, design criteria, supporting technology, damage tolerance, and manufacturing. Separate abstracts have been prepared for articles from this report.

  19. Composite structures of steel and concrete beams, slabs, columns, and frames for buildings

    CERN Document Server

    Johnson, R P

    2008-01-01

    This book sets out the basic principles of composite construction with reference to beams, slabs, columns and frames, and their applications to building structures. It deals with the problems likely to arise in the design of composite members in buildings, and relates basic theory to the design approach of Eurocodes 2, 3 and 4.The new edition is based for the first time on the finalised Eurocode for steel/concrete composite structures.

  20. Durability-Based Design Criteria for a Chopped-Glass-Fiber Automotive Structural Composite; TOPICAL

    International Nuclear Information System (INIS)

    Battiste, R.L.; Corum, J.M.; Ren, W.; Ruggles, M.B.

    1999-01-01

    This report provides recommended durability-based design criteria for a chopped-glass-fiber reinforced polymeric composite for automotive structural applications. The criteria closely follow the framework of an earlier criteria document for a continuous-strand-mat (CSM) glass-fiber reference composite. Together these design criteria demonstrate a framework that can be adapted for future random-glass-fiber composites for automotive structural applications

  1. Constraints on Stress Components at the Internal Singular Point of an Elastic Compound Structure

    Science.gov (United States)

    Pestrenin, V. M.; Pestrenina, I. V.

    2017-03-01

    The classical analytical and numerical methods for investigating the stress-strain state (SSS) in the vicinity of a singular point consider the point as a mathematical one (having no linear dimensions). The reliability of the solution obtained by such methods is valid only outside a small vicinity of the singular point, because the macroscopic equations become incorrect and microscopic ones have to be used to describe the SSS in this vicinity. Also, it is impossible to set constraint or to formulate solutions in stress-strain terms for a mathematical point. These problems do not arise if the singular point is identified with the representative volume of material of the structure studied. In authors' opinion, this approach is consistent with the postulates of continuum mechanics. In this case, the formulation of constraints at a singular point and their investigation becomes an independent problem of mechanics for bodies with singularities. This method was used to explore constraints at an internal singular point (representative volume) of a compound wedge and a compound rib. It is shown that, in addition to the constraints given in the classical approach, there are also constraints depending on the macroscopic parameters of constituent materials. These constraints turn the problems of deformable bodies with an internal singular point into nonclassical ones. Combinations of material parameters determine the number of additional constraints and the critical stress state at the singular point. Results of this research can be used in the mechanics of composite materials and fracture mechanics and in studying stress concentrations in composite structural elements.

  2. Design and Manufacturing of Composite Tower Structure for Wind Turbine Equipment

    Science.gov (United States)

    Park, Hyunbum

    2018-02-01

    This study proposes the composite tower design process for large wind turbine equipment. In this work, structural design of tower and analysis using finite element method was performed. After structural design, prototype blade manufacturing and test was performed. The used material is a glass fiber and epoxy resin composite. And also, sand was used in the middle part. The optimized structural design and analysis was performed. The parameter for optimized structural design is weight reduction and safety of structure. Finally, structure of tower will be confirmed by structural test.

  3. International society of sports nutrition position stand: diets and body composition.

    Science.gov (United States)

    Aragon, Alan A; Schoenfeld, Brad J; Wildman, Robert; Kleiner, Susan; VanDusseldorp, Trisha; Taylor, Lem; Earnest, Conrad P; Arciero, Paul J; Wilborn, Colin; Kalman, Douglas S; Stout, Jeffrey R; Willoughby, Darryn S; Campbell, Bill; Arent, Shawn M; Bannock, Laurent; Smith-Ryan, Abbie E; Antonio, Jose

    2017-01-01

    Position Statement: The International Society of Sports Nutrition (ISSN) bases the following position stand on a critical analysis of the literature regarding the effects of diet types (macronutrient composition; eating styles) and their influence on body composition. The ISSN has concluded the following. 1) There is a multitude of diet types and eating styles, whereby numerous subtypes fall under each major dietary archetype. 2) All body composition assessment methods have strengths and limitations. 3) Diets primarily focused on fat loss are driven by a sustained caloric deficit. The higher the baseline body fat level, the more aggressively the caloric deficit may be imposed. Slower rates of weight loss can better preserve lean mass (LM) in leaner subjects. 4) Diets focused primarily on accruing LM are driven by a sustained caloric surplus to facilitate anabolic processes and support increasing resistance-training demands. The composition and magnitude of the surplus, as well as training status of the subjects can influence the nature of the gains. 5) A wide range of dietary approaches (low-fat to low-carbohydrate/ketogenic, and all points between) can be similarly effective for improving body composition. 6) Increasing dietary protein to levels significantly beyond current recommendations for athletic populations may result in improved body composition. Higher protein intakes (2.3-3.1 g/kg FFM) may be required to maximize muscle retention in lean, resistance-trained subjects under hypocaloric conditions. Emerging research on very high protein intakes (>3 g/kg) has demonstrated that the known thermic, satiating, and LM-preserving effects of dietary protein might be amplified in resistance-training subjects. 7) The collective body of intermittent caloric restriction research demonstrates no significant advantage over daily caloric restriction for improving body composition. 8) The long-term success of a diet depends upon compliance and suppression or

  4. Optimal Realtime Damage Identification in Composite Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Intelligent Fiber Optic Systems Corporation (IFOS) proposes to develop an effective real-time, in situ damage locating and growth monitoring system of composite...

  5. Structural Analysis of Ciprofloxacin-Carbopol Polymeric Composites ...

    African Journals Online (AJOL)

    Erah

    Methods: The ciprofloxacin and Carbopol were mixed in water in a drug:polymer ratio of 1:5 ... and the Carbopol polymeric composites of the drug were obtained using a powder diffractometer. .... 2950 cm-1 represented alkenes and aromatic.

  6. Reduced Cost Composite Hot Structures with Oxidation Protection, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Innovative, low cost high performance technologies are critical to the affordability of future space missions. Carbon/carbon (C/C) composites have significant...

  7. Novel, Nanotechnology Based CMC composites for Hot Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Very extensive R&D efforts over the past several decades resulted in several classes of high temperature composites offering potential for future hypersonic...

  8. Contribution of SELENE-2 geodetic measurements to constrain the lunar internal structure

    Science.gov (United States)

    Matsumoto, K.; Kikuchi, F.; Yamada, R.; Iwata, T.; Kono, Y.; Tsuruta, S.; Hanada, H.; Goossens, S. J.; Ishihara, Y.; Kamata, S.; Sasaki, S.

    2012-12-01

    Internal structure and composition of the Moon provide important clue and constraints on theories for how the Moon formed and evolved. The Apollo seismic network has contributed to the internal structure modeling. Efforts have been made to detect the lunar core from the noisy Apollo data (e.g., [1], [2]), but there is scant information about the structure below the deepest moonquakes at about 1000 km depth. On the other hand, there have been geodetic studies to infer the deep structure of the Moon. For example, LLR (Lunar Laser Ranging) data analyses detected a displacement of the lunar pole of rotation, indicating that dissipation is acting on the rotation arising from a fluid core [3]. Bayesian inversion using geodetic data (such as mass, moments of inertia, tidal Love numbers k2 and h2, and quality factor Q) also suggests a fluid core and partial melt in the lower mantle region [4]. Further improvements in determining the second-degree gravity coefficients (which will lead to better estimates of moments of inertia) and the Love number k2 will help us to better constrain the lunar internal structure. Differential VLBI (Very Long Baseline Interferometry) technique, which was used in the Japanese lunar exploration mission SELENE (Sept. 2007 - June 2009), is expected to contribute to better determining the second-degree potential Love number k2 and low-degree gravity coefficients. SELENE will be followed by the future lunar mission SELENE-2 which will carry both a lander and an orbiter. We propose to put the SELENE-type radio sources on these spacecraft in order to accurately estimate k2 and the low-degree gravity coefficients. By using the same-beam VLBI tracking technique, these parameters will be retrieved through precision orbit determination of the orbiter with respect to the lander which serves as a reference. The VLBI mission with the radio sources is currently one of the mission candidates for SELENE-2. We have conducted a preliminary simulation study on the

  9. Metal Matrix Composite Enchanced Aluminum Structures, Phase I

    Data.gov (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...

  10. Metal Matrix Composite Enchanced Aluminum Structures, Phase II

    Data.gov (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...

  11. Body Composition and Survival in Dialysis Patients: Results from an International Cohort Study

    Science.gov (United States)

    Usvyat, Len A.; Kotanko, Peter; Bayh, Inga; Canaud, Bernard; Etter, Michael; Gatti, Emanuele; Grassmann, Aileen; Wang, Yuedong; Marelli, Cristina; Scatizzi, Laura; Stopper, Andrea; van der Sande, Frank M.; Kooman, Jeroen

    2015-01-01

    Background and objectives High body mass index appears protective in hemodialysis patients, but uncertainty prevails regarding which components of body composition, fat or lean body mass, are primarily associated with survival. Design, setting, participants, & measurements Data between April 2006 and December 2012 were extracted from the Fresenius Medical Care Europe subset of the international MONitoring Dialysis Outcomes initiative. Fresenius Medical Care Europe archives a unique repository of predialysis body composition measurements determined by multifrequency bioimpedance (BCM Body Composition Monitor). The BCM Body Composition Monitor reports lean tissue indices (LTIs) and fat tissue indices (FTIs), which are the respective tissue masses normalized to height squared, relative to an age- and sex-matched healthy population. The relationship between LTI and FTI and all-cause mortality was studied by Kaplan–Meier analysis, multivariate Cox regression, and smoothing spline ANOVA logistic regression. Results In 37,345 hemodialysis patients, median (25th–75th percentile) LTI and FTI were 12.2 (10.3–14.5) and 9.8 (6.6–12.4) kg/m2, respectively. Median (25th–75th percentile) follow-up time was 266 (132–379) days; 3458 (9.2%) patients died during follow-up. Mortality was lowest with both LTI and FTI in the 10th–90th percentile (reference group) and significantly higher at the lower LTI and FTI extreme (hazard ratio [HR], 3.37; 95% confidence interval [95% CI], 2.94 to 3.87; P<0.001). Survival was best with LTI between 15 and 20 kg/m2 and FTI between 4 and 15 kg/m2 (probability of death during follow-up: <5%). When taking the relation between both compartments into account, the interaction was significant (P=0.01). Higher FTI appeared protective in patients with low LTI (HR, 3.37; 95% CI, 2.94 to 3.87; P<0.001 at low LTI–low FTI, decreasing to HR, 1.79; 95% CI, 1.47 to 2.17; P<0.001 at low LTI–high FTI). Conclusions This large international study

  12. Discrete Material Buckling Optimization of Laminated Composite Structures considering "Worst" Shape Imperfections

    DEFF Research Database (Denmark)

    Henrichsen, Søren Randrup; Lindgaard, Esben; Lund, Erik

    2015-01-01

    Robust design of laminated composite structures is considered in this work. Because laminated composite structures are often thin walled, buckling failure can occur prior to material failure, making it desirable to maximize the buckling load. However, as a structure always contains imperfections...... and “worst” shape imperfection optimizations to design robust composite structures. The approach is demonstrated on an U-profile where the imperfection sensitivity is monitored, and based on the example it can be concluded that robust designs can be obtained....

  13. Structural and physico-mechanical properties of natural rubber/GTR composites devulcanized by microwaves: influence of GTR source and irradiation time

    OpenAIRE

    Colom Fajula, Xavier; Marin-Genesca, Marc; Mujal Rosas, Ramón María; Formela, Krzysztof; Cañavate Ávila, Francisco Javier

    2018-01-01

    Ground tire rubber from car and truck was modified using microwave irradiation at variable time. The irradiated ground tire rubber was used as filler in composites based on natural rubber. The composites, with high content of ground tire rubber, were prepared using an internal batch mixer and subsequently cross-linked at 160¿. The influence of the ground tire rubber source (car/truck) and irradiation time on structure, physico-mechanical behaviour, thermal properties and morphology of natural...

  14. Template-free fabrication and morphology regulation of Ag@carbon composite structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenyan, E-mail: zhangwenyan8531@gmail.com [College of Material Engineering, Jinling Institute of Technology, Nanjing (China); Hao, Lingyun; Lin, Qin [College of Material Engineering, Jinling Institute of Technology, Nanjing (China); Lu, Chunhua; Xu, Zhongzi [College of Materials Science and Engineering, Nanjing Technology University, Nanjing (China); Chen, Xiaoyu [College of Material Engineering, Jinling Institute of Technology, Nanjing (China)

    2014-12-15

    Graphical abstract: - Highlights: • A simple and low-cost method to prepare Ag@C composite material. • AgNO{sub 3} plays an important role in tuning size and functional groups of products. • HTC reaction time is also a key factor for regulating the Ag@C structure. - Abstract: Ag–carbon composite materials were prepared without any template by hydrothermal carbonization of solvable starch. The composite materials are composed of Ag cores and carbonaceous shell to form a core–shell (Ag@carbon) structure. During the hydrothermal carbonization process, the aromatization and carbonization of solvable starch endowed the Ag@carbon composite structure with abundant aromatic, hydroxyl and carbonyl groups. The AgNO{sub 3} concentration and HTC reaction time are two important factors for regulating the size, morphology and functional groups of the composite material. With the increasing of AgNO{sub 3} concentration, morphologies of the composite material turned from spheres to wires.

  15. Glyceride structure and sterol composition of SOS-7 halophyte oil

    Directory of Open Access Journals (Sweden)

    El-Shami, S. M.

    1991-06-01

    Full Text Available Glyceride structure of SOS-7 halophyte oil was studied using the lipase hydrolysis technique. This halophyte sample was obtained from 1988 harvest planted in Ghardaka, on the border of the Red Sea, Egypt. The oilseed was ground and extracted for its oil using commercial hexane in Soxhlet extractor. The unsaturated fatty acids were found centralized in the 2-position of triglycerides, whereas oleic and linolenic acids showed more preference for this position. It was found that P3 was the major component of GS3, whereas P2L and PStL; PL2, POL and StL2 are predominating among GS2U and GSU3 respectively. L3 manifested itself as the principal constituent of GU3 type. Sterol composition of the halophyte oil was determined by GLC as TMS derivative. It was found that the oil contains campsterol, β-sitosterol, stigmasterol and 7-stigmasterol of which 7-stigmasterol is the major sterol and constitute 52.4%.

    Se ha estudiado usando la técnica de hidrólisis mediante lipasa la estructura glicerídica de aceite de halofito SOS-7. Esta muestra de halofito fue obtenida a partir de una cosecha de 1988 plantada en Ghardaka, en la orilla del Mar Rojo, Egipto. Para la extracción del aceite de la semilla molida se utilizó hexano comercial en extractor Soxhlet. Los ácidos grasos insaturados se encontraron centralizados en la posición 2 de los triglicéridos, siendo los ácidos oleico y linolénico los que mostraron mayor preferencia por esta posición. Se encontró que P3 fue el componente mayoritario de GS3, mientras que P2L y PStL; PL2 POL y StL2 son los predominantes para GS2U y GSU3 respectivamente. L3 se manifestó como el principal constituyente de los GU3. La composición esterólica del aceite de halofito se determinó por GLC como derivados del

  16. Development of an ultrasonic nondestructive inspection method for impact damage detection in composite aircraft structures

    Science.gov (United States)

    Capriotti, M.; Kim, H. E.; Lanza di Scalea, F.; Kim, H.

    2017-04-01

    High Energy Wide Area Blunt Impact (HEWABI) due to ground service equipment can often occur in aircraft structures causing major damages. These Wide Area Impact Damages (WAID) can affect the internal components of the structure, hence are usually not visible nor detectable by typical one-sided NDE techniques and can easily compromise the structural safety of the aircraft. In this study, the development of an NDI method is presented together with its application to impacted aircraft frames. The HEWABI from a typical ground service scenario has been previously tested and the desired type of damages have been generated, so that the aircraft panels could become representative study cases. The need of the aircraft industry for a rapid, ramp-friendly system to detect such WAID is here approached with guided ultrasonic waves (GUW) and a scanning tool that accesses the whole structure from the exterior side only. The wide coverage of the specimen provided by GUW has been coupled to a differential detection approach and is aided by an outlier statistical analysis to be able to inspect and detect faults in the challenging composite material and complex structure. The results will be presented and discussed with respect to the detection capability of the system and its response to the different damage types. Receiving Operating Characteristics curves (ROC) are also produced to quantify and assess the performance of the proposed method. Ongoing work is currently aimed at the penetration of the inner components of the structure, such as shear ties and C-frames, exploiting different frequency ranges and signal processing techniques. From the hardware and tool development side, different transducers and coupling methods, such as air-coupled transducers, are under investigation together with the design of a more suitable scanning technique.

  17. Dip-Test Internal Stress and the Composite Model of Creep Deformation

    Czech Academy of Sciences Publication Activity Database

    Dobeš, Ferdinand; Orlová, Alena

    2005-01-01

    Roč. 482, - (2005), s. 291-294 ISSN 0255-5476. [Materials Structure & Micromechanics of Fracture /4./. Brno, 23.06.2004-25.06.2004] R&D Pro jects: GA AV ČR(CZ) IAA2041202 Institutional research plan: CEZ:AV0Z20410507 Keywords : creep * internal stress * subgrain Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.399, year: 2005

  18. Mechanical properties and material characterization of polysialate structural composites

    Science.gov (United States)

    Foden, Andrew James

    One of the major concerns in using Fiber Reinforced Composites in applications that are subjected to fire is their resistance to high temperature. Some of the fabrics used in FRC, such as carbon, are fire resistant. However, almost all the resins used cannot withstand temperatures higher than 200°C. This dissertation deals with the development and use of a potassium aluminosilicate (GEOPOLYMER) resin that is inorganic and can sustain more than 1000°C. The results presented include the mechanical properties of the unreinforced polysialate matrix in tension, flexure, and compression as well as the strain capacities and surface energy. The mechanical properties of the matrix reinforced with several different fabrics were obtained in flexure, tension, compression and shear. The strength and stiffness of the composite was evaluated for each loading condition. Tests were conducted on unexposed samples as well as samples exposed to temperatures from 200 to 1000°C. Fatigue properties were determined using flexural loading. A study of the effect of several processing variables on the properties of the composite was undertaken to determine the optimum procedure for manufacturing composite plates. The processing variables studied were the curing temperature and pressure, and the post cure drying time required to remove any residual water. The optimum manufacturing conditions were determined using the void content, density, fiber volume fraction, and flexural strength. Analytical models are presented based on both micro and macro mechanical analysis of the composite. Classic laminate theory is used to evaluate the state of the composite as it is being loaded to determine the failure mechanisms. Several failure criteria theories are considered. The analysis is then used to explain the mechanical behavior of the composite that was observed during the experimental study.

  19. Impact damage response of natural stitched single lap-joint in composite structures

    International Nuclear Information System (INIS)

    Ghasemnejad, H.; Argentiero, Y.; Tez, T.A.; Barrington, P.E.

    2013-01-01

    Highlights: • To study the impact resistance of single lap-joints in composite structures. • To improve the impact resistance of stitched single lap joints using natural Flax yarn. • To investigate the effect of stitching on the damage process of composite materials. • To develop FE techniques to model the impact process of composite structures using LSDYNA. - Abstract: In this paper the damage behaviour of natural stitched composite single lap-joints are investigated under low velocity impact loading conditions. For this study, the laminated hybrid composite beams were pinned using Flax yarns before curing process. The Charpy impact test was chosen to study the energy absorbing capability of single lap composite joints. Composite beams were fabricated from combination of glass/epoxy and carbon/epoxy composites. It was shown that composite beams which are stitched through the thickness are able to absorb more energy in comparison with adhesive bonded composite joints in the hybrid composite beams. The Charpy impact test of stitched composite single lap joint was also simulated by finite element analysis using software LS-DYNA and the results verified with relevant experimental data

  20. Structure evaluation of cast dispersive AlSi-CrxCy composites

    OpenAIRE

    M. Cholewa

    2008-01-01

    In this work author showed the diversification of structure for cast dispersive AlSi-CrxCy composites. Wide possibilities of properties control and optimization were described, through microstructure of the matrix and the transition zone shaping. Utility castings were prepared with use of traditional casting techniques, ceramic and metal moulds. The influence of technological conditions and cooling rate ion the composite structure was studied. The main factor of structural changes was the dif...

  1. The Packaging Technology Study on Smart Composite Structure Based on The Embedded FBG Sensor

    Science.gov (United States)

    Zhang, Youhong; Chang, Xinlong; Zhang, Xiaojun; He, Xiangyong

    2018-03-01

    It is convenient to carry out the health monitoring of the solid rocket engine composite shell based on the embedded FBG sensor. In this paper, the packaging technology using one-way fiber layer of prepreg fiberglass/epoxy resin was proposed. The proposed packaging process is simple, and the packaged sensor structure size is flexible and convenient to use, at the mean time, the packaged structure has little effect on the pristine composite material structure.

  2. Structural and compositional features of high-rise buildings: experimental design in Yekaterinburg

    Science.gov (United States)

    Yankovskaya, Yulia; Lobanov, Yuriy; Temnov, Vladimir

    2018-03-01

    The study looks at the specifics of high-rise development in Yekaterinburg. High-rise buildings are considered in the context of their historical development, structural features, compositional and imaginative design techniques. Experience of Yekaterinburg architects in experimental design is considered and analyzed. Main issues and prospects of high-rise development within the Yekaterinburg structure are studied. The most interesting and significant conceptual approaches to the structural and compositional arrangement of high-rise buildings are discussed.

  3. A Fragment-Cloud Model for Breakup of Asteroids with Varied Internal Structures

    Science.gov (United States)

    Wheeler, Lorien; Mathias, Donovan; Stokan, Ed; Brown, Peter

    2016-01-01

    As an asteroid descends toward Earth, it deposits energy in the atmosphere through aerodynamic drag and ablation. Asteroid impact risk assessments rely on energy deposition estimates to predict blast overpressures and ground damage that may result from an airburst, such as the one that occurred over Chelyabinsk, Russia in 2013. The rates and altitudes at which energy is deposited along the entry trajectory depend upon how the bolide fragments, which in turn depends upon its internal structure and composition. In this work, we have developed an analytic asteroid fragmentation model to assess the atmospheric energy deposition of asteroids with a range of structures and compositions. The modeling approach combines successive fragmentation of larger independent pieces with aggregate debris clouds released with each fragmentation event. The model can vary the number and masses of fragments produced, the amount of mass released as debris clouds, the size-strength scaling used to increase the robustness of smaller fragments, and other parameters. The initial asteroid body can be seeded with a distribution of independent fragment sizes amid a remaining debris mass to represent loose rubble pile conglomerations, can be given an outer regolith later, or can be defined as a coherent or fractured monolith. This approach enables the model to represent a range of breakup behaviors and reproduce detailed energy deposition features such as multiple flares due to successive burst events, high-altitude regolith blow-off, or initial disruption of rubble piles followed by more energetic breakup of the constituent boulders. These capabilities provide a means to investigate sensitivities of ground damage to potential variations in asteroid structure.

  4. Development of Shear Connections in Steelconcrete Composite Structures

    Science.gov (United States)

    Biegus, Antoni; Lorenc, Wojciech

    2015-03-01

    Different types of shear connectors and modelling techniques are presented. Basic research conducted or presented after year 2000 is taken into consideration, following the idea of concrete dowel implemented in the form of perfobond strip at the beginning of the 1980s by F. Leonhardt. The latest research in the field of continuous shear connectors applied in bridges is highlited with special focus at the composite dowel shear connection, as it seems to be the most modern solution being strongly introduced to the industry. Final shape of composite dowel shear connection is presented.

  5. Structural and compositional gradients: basic idea, preparation, applications

    International Nuclear Information System (INIS)

    Ilschner, B.

    1993-01-01

    The term gradient materials refers to gradients of chemical composition and/or microstructural parameters which are intentionally introduced into components of any kind of homogeneous or heterogeneous materials, including metallic alloys, ceramics, glasses, polymers, and composites. After a short review of the development of the gradient materials technology since 1972, some fundamental aspects concerning the effects of such gradients on physical or mechanical properties are discussed. A selection of technical applications which have been discussed recently is presented. Finally, different methods for the preparation of gradients from gaseous, liquid or powder precursors are reviewed. (orig.)

  6. An investigation of sustainable and recyclable composites for structural applications

    Science.gov (United States)

    Moller, Johannes Paul

    Motivated by the need for more sustainable materials in general and the issues concerning the life cycle of wind turbine blades in particular, the focus of this research work is to better understand what is needed to create high-performance bio-epoxy composites, and to explore their repair and recycling. To further these ends, glass fiber reinforced composites were manufactured using an epoxidized linseed oil (ELO) based matrix cured with various anhydride curatives and catalysts. Based on mechanical properties measurements of these materials, ELO cured with methyltetrahydrophthalic anhydride (MTHPA) and catalyzed with 2-ethyl-4-methylimidazole (2E4MI) yielded the best performance among all fou iulations tested, and avoided the void foiniation issues associated with the use of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as a catalyst. In addition to the mechanical characterization of the composite, the applicability and processability of a range of bio-epoxy formulations was evaluated in the context of for vacuum-assisted resin transfer molding (VARTM). In particular, a new methodology for assessing the infusability of a resin was developed and the bioepoxy formulations were demonstrated to be more amenable to resin infusion than a conventional control. Having demonstrated the potential for bio-based resins to produce more sustainable high-performance composites, further studies were carried out to address end-of-life issues. Here different approaches for healing and recycling of epoxy vitrimers (epoxies rendered reworkable by the inclusion of a transesterification catalyst) and their composites were introduced and proof-of-concept experiments were performed. By exposing a fractured glass fiber epoxy vitrimer composite to elevated temperatures and pressure for times on the order often minutes, a healing efficiency of 55% was achieved. Additionally, two different recycling approaches were explored. First, mechnical recycling (grinding followed by reconsolidation via

  7. Structural Framework for Flight: NASA's Role in Development of Advanced Composite Materials for Aircraft and Space Structures

    Science.gov (United States)

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

    2011-01-01

    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.

  8. Hierarchical system for autonomous sensing-healing of delamination in large-scale composite structures

    International Nuclear Information System (INIS)

    Minakuchi, Shu; Sun, Denghao; Takeda, Nobuo

    2014-01-01

    This study combines our hierarchical fiber-optic-based delamination detection system with a microvascular self-healing material to develop the first autonomous sensing-healing system applicable to large-scale composite structures. In this combined system, embedded vascular modules are connected through check valves to a surface-mounted supply tube of a pressurized healing agent while fiber-optic-based sensors monitor the internal pressure of these vascular modules. When delamination occurs, the healing agent flows into the vascular modules breached by the delamination and infiltrates the damage for healing. At the same time, the pressure sensors identify the damaged modules by detecting internal pressure changes. This paper begins by describing the basic concept of the combined system and by discussing the advantages that arise from its hierarchical nature. The feasibility of the system is then confirmed through delamination infiltration tests. Finally, the hierarchical system is validated in a plate specimen by focusing on the detection and infiltration of the damage. Its self-diagnostic function is also demonstrated. (paper)

  9. Energy Finite Element Analysis Developments for Vibration Analysis of Composite Aircraft Structures

    Science.gov (United States)

    Vlahopoulos, Nickolas; Schiller, Noah H.

    2011-01-01

    The Energy Finite Element Analysis (EFEA) has been utilized successfully for modeling complex structural-acoustic systems with isotropic structural material properties. In this paper, a formulation for modeling structures made out of composite materials is presented. An approach based on spectral finite element analysis is utilized first for developing the equivalent material properties for the composite material. These equivalent properties are employed in the EFEA governing differential equations for representing the composite materials and deriving the element level matrices. The power transmission characteristics at connections between members made out of non-isotropic composite material are considered for deriving suitable power transmission coefficients at junctions of interconnected members. These coefficients are utilized for computing the joint matrix that is needed to assemble the global system of EFEA equations. The global system of EFEA equations is solved numerically and the vibration levels within the entire system can be computed. The new EFEA formulation for modeling composite laminate structures is validated through comparison to test data collected from a representative composite aircraft fuselage that is made out of a composite outer shell and composite frames and stiffeners. NASA Langley constructed the composite cylinder and conducted the test measurements utilized in this work.

  10. Nonlinear Finite Element Analysis of a Composite Non-Cylindrical Pressurized Aircraft Fuselage Structure

    Science.gov (United States)

    Przekop, Adam; Wu, Hsi-Yung T.; Shaw, Peter

    2014-01-01

    The Environmentally Responsible Aviation Project aims to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration are not sufficient to achieve the desired metrics. One of the airframe concepts that might dramatically improve aircraft performance is a composite-based hybrid wing body configuration. Such a concept, however, presents inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses a nonlinear finite element analysis of a large-scale test article being developed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. There are specific reasons why geometrically nonlinear analysis may be warranted for the hybrid wing body flat panel structure. In general, for sufficiently high internal pressure and/or mechanical loading, energy related to the in-plane strain may become significant relative to the bending strain energy, particularly in thin-walled areas such as the minimum gage skin extensively used in the structure under analysis. To account for this effect, a geometrically nonlinear strain-displacement relationship is needed to properly couple large out-of-plane and in-plane deformations. Depending on the loading, this nonlinear coupling mechanism manifests itself in a distinct manner in compression- and tension-dominated sections of the structure. Under significant compression, nonlinear analysis is needed to accurately predict loss of stability and postbuckled deformation. Under significant tension, the nonlinear effects account for suppression of the out-of-plane deformation due to in-plane stretching. By comparing the present results with the previously

  11. Interface structure and strength in model dental resin composites

    DEFF Research Database (Denmark)

    Nielsen, Mette Skovgaard

    . This will facilitate discoloration by colorants from e.g. coffee and red wine entering the crack, or even worse lead to secondary caries and infection of dental pulp due to bacteria. The aim of this study was to develop a low shrinkage dental composite based on an expandable metastable zirconia filler A metastable...

  12. Sustainable Use of Tepetate Composite in Earthen Structure

    Directory of Open Access Journals (Sweden)

    T. López-Lara

    2013-01-01

    Full Text Available One of the best indicators for construction sustainability is the use of earthy local materials which are completely recyclables and savers of energy during their life cycle. Tepetate is an underestimated earth-natural material, vast and economic, used only in a compacted form in backfills for layers of low resistance in pavements and platforms of buildings. This volcanic soil, named in different ways in several countries, is found in the central region of Mexico. Its resistance as compacted material is very low, of the order of 0.08 MPa. In this work, an improved sustainable-tepetate composite, using CaOH, is presented. This research includes the determination of mechanical properties as well as the physicochemical characterization of the sustainable-tepetate composite behavior. It can be concluded that the strength of the proposed composite increases significantly, immediately after treatment and with time. X-Ray Diffraction shows that all the mineralogical phases prevail in the natural tepetate and only a new phase appeared (calcite, which increases with time. This and the reaction of CaOH with clay content are very likely associated with the continuous strength increase of the composite.

  13. Optimal Design of Variable Stiffness Composite Structures using Lamination Parameters

    NARCIS (Netherlands)

    IJsselmuiden, S.T.

    2011-01-01

    Fiber reinforced composite materials have gained widespread acceptance for a multitude of applications in the aerospace, automotive, maritime and wind-energy industries. Automated fiber placement technologies have developed rapidly over the past two decades, driven primarily by a need to reduce

  14. Development of hybrid composite radar wave absorbing structure for ...

    Indian Academy of Sciences (India)

    epoxy composite and balsa wood instead of PVC foam as the two have low dielectric properties and the latter has greater mechanical strength. 2. Specification of the materials used. The plain weave E-glass fibre and epoxy resin is purchased.

  15. Damage assessment of composite plate structures with material and measurement uncertainty

    Science.gov (United States)

    Chandrashekhar, M.; Ganguli, Ranjan

    2016-06-01

    Composite materials are very useful in structural engineering particularly in weight sensitive applications. Two different test models of the same structure made from composite materials can display very different dynamic behavior due to large uncertainties associated with composite material properties. Also, composite structures can suffer from pre-existing imperfections like delaminations, voids or cracks during fabrication. In this paper, we show that modeling and material uncertainties in composite structures can cause considerable problem in damage assessment. A recently developed C0 shear deformable locking free refined composite plate element is employed in the numerical simulations to alleviate modeling uncertainty. A qualitative estimate of the impact of modeling uncertainty on the damage detection problem is made. A robust Fuzzy Logic System (FLS) with sliding window defuzzifier is used for delamination damage detection in composite plate type structures. The FLS is designed using variations in modal frequencies due to randomness in material properties. Probabilistic analysis is performed using Monte Carlo Simulation (MCS) on a composite plate finite element model. It is demonstrated that the FLS shows excellent robustness in delamination detection at very high levels of randomness in input data.

  16. Development of on-line condition monitoring system in aerospace structures using advanced composite materials

    International Nuclear Information System (INIS)

    Khan, Z.M.

    2005-01-01

    This research aims to develop condition monitoring systems for advanced aerospace composite structures. To perform these functions successfully a smart system is required that could autonomously respond to environmental changes. The integrated structure senses the environments, conveys the message to central processing unit and reacts instantaneously to external stimuli. Such structures not only monitor their own health but also for warn about onset of failures, fatigue and impending disasters. This required development of methods for embedding optical fibers in composite panels for sensing given defect. The thick and cylindrical composite structures have layer waviness due to fiber microbend defect. Such kind of defect is characteristically hard to detect. It leads to delamination, cracking and deterioration of mechanical properties. The experimental investigation revealed correlation of the intensity of light with the microbend defect in composite structure. (author)

  17. Topology Optimization of Lightweight Lattice Structural Composites Inspired by Cuttlefish Bone

    Science.gov (United States)

    Hu, Zhong; Gadipudi, Varun Kumar; Salem, David R.

    2018-03-01

    Lattice structural composites are of great interest to various industries where lightweight multifunctionality is important, especially aerospace. However, strong coupling among the composition, microstructure, porous topology, and fabrication of such materials impedes conventional trial-and-error experimental development. In this work, a discontinuous carbon fiber reinforced polymer matrix composite was adopted for structural design. A reliable and robust design approach for developing lightweight multifunctional lattice structural composites was proposed, inspired by biomimetics and based on topology optimization. Three-dimensional periodic lattice blocks were initially designed, inspired by the cuttlefish bone microstructure. The topologies of the three-dimensional periodic blocks were further optimized by computer modeling, and the mechanical properties of the topology optimized lightweight lattice structures were characterized by computer modeling. The lattice structures with optimal performance were identified.

  18. Methodology for repeated load analysis of composite structures with embedded magnetic microwires

    Directory of Open Access Journals (Sweden)

    K. Semrád

    2017-01-01

    Full Text Available The article processes issue of strength of cyclically loaded composite structures with the possibility of contactless stress measuring inside a material. For this purpose a contactless tensile stress sensor using improved induction principle based on the magnetic microwires embedded in the composite structure has been developed. The methodology based on the E-N approach was applied for the analysis of the repeated load of the wing hinge connection, including finite element method (FEM fatigue strength analysis. The results proved that composites in comparison with the metal structures offer significant weight reduction of the small aircraft construction, whereas the required strength, stability and lifetime of the components are remained.

  19. A Multiscale, Nonlinear, Modeling Framework Enabling the Design and Analysis of Composite Materials and Structures

    Science.gov (United States)

    Bednarcyk, Brett A.; Arnold, Steven M.

    2012-01-01

    A framework for the multiscale design and analysis of composite materials and structures is presented. The ImMAC software suite, developed at NASA Glenn Research Center, embeds efficient, nonlinear micromechanics capabilities within higher scale structural analysis methods such as finite element analysis. The result is an integrated, multiscale tool that relates global loading to the constituent scale, captures nonlinearities at this scale, and homogenizes local nonlinearities to predict their effects at the structural scale. Example applications of the multiscale framework are presented for the stochastic progressive failure of a SiC/Ti composite tensile specimen and the effects of microstructural variations on the nonlinear response of woven polymer matrix composites.

  20. Fabrication of submicron structures in nanoparticle/polymer composite by holographic lithography and reactive ion etching

    Science.gov (United States)

    Zhang, A. Ping; He, Sailing; Kim, Kyoung Tae; Yoon, Yong-Kyu; Burzynski, Ryszard; Samoc, Marek; Prasad, Paras N.

    2008-11-01

    We report on the fabrication of nanoparticle/polymer submicron structures by combining holographic lithography and reactive ion etching. Silica nanoparticles are uniformly dispersed in a (SU8) polymer matrix at a high concentration, and in situ polymerization (cross-linking) is used to form a nanoparticle/polymer composite. Another photosensitive SU8 layer cast upon the nanoparticle/SU8 composite layer is structured through holographic lithography, whose pattern is finally transferred to the nanoparticle/SU8 layer by the reactive ion etching process. Honeycomb structures in a submicron scale are experimentally realized in the nanoparticle/SU8 composite.

  1. Results of the international Pu-2000 exercise for plutonium isotopic composition measurements

    International Nuclear Information System (INIS)

    Morel, J.; Bickel, M.; Hill, C.; Verbruggen, A.

    2004-01-01

    An international comparison for plutonium isotopic composition measurement, known as the Pu-2000 exercise, was organized by the ESARDA NDA-WG (European Safeguards Research and Development Association, Working Group on Techniques and Standards for Non-Destructive Assay). The aim of this comparison was to test X- and γ-ray spectrometry methods over a large range of isotopic ratios. These methods are based on the complex analysis of several X- and γ-rays in the KX region of the plutonium spectrum and also in the 120-700 keV energy range. The results obtained by the participants with their corresponding uncertainties are presented in this document and compared to the declared values. The main conclusions of the work are also given. No important bias due to an inadequate knowledge of the nuclear data for plutonium isotopes was observed

  2. A formalism for scattering of complex composite structures. I. Applications to branched structures of asymmetric sub-units

    DEFF Research Database (Denmark)

    Svaneborg, Carsten; Pedersen, Jan Skov

    2012-01-01

    to structural connectivity is completely decoupled from internal structure of the sub-units. This allows sub-units to be replaced by more complex structures. We illustrate the physical interpretation of the formalism diagrammatically. By applying a self-consistency requirement, we derive the pair distributions...

  3. Social Structures in the Economics of International Education: Perspectives from Vietnamese International Tertiary Students

    Science.gov (United States)

    Pham, Lien

    2013-01-01

    Drawing on the findings from in-depth interviews with Vietnamese international students studying at Australian universities, this article presents insights into the sociological influences that stem from international students' social networks, at home and abroad, and how they impact on students' aspirations and engagement in international…

  4. Rotational Spectrum of 1,1-Difluoroethane: Internal Rotation Analysis and Structure

    Science.gov (United States)

    Villamanan, R. M.; Chen, W. D.; Wlodarczak, G.; Demaison, J.; Lesarri, A. G.; Lopez, J. C.; Alonso, J. L.

    1995-05-01

    The rotational spectrum of CH3CHF2 in its ground state was measured up to 653 GHz. Accurate rotational and centrifugal distortion constants were determined. The internal rotation splittings were analyzed using the internal axis method. An ab initio structure has been calculated and a near-equilibrium structure has been estimated using offsets derived empirically. This structure was compared to an experimental r0 structure. The four lowest excited states (including the methyl torsion) have also been assigned.

  5. Sandwich Structured Composites for Aeronautics: Methods of Manufacturing Affecting Some Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Aneta Krzyżak

    2016-01-01

    Full Text Available Sandwich panels are composites which consist of two thin laminate outer skins and lightweight (e.g., honeycomb thick core structure. Owing to the core structure, such composites are distinguished by stiffness. Despite the thickness of the core, sandwich composites are light and have a relatively high flexural strength. These composites have a spatial structure, which affects good thermal insulator properties. Sandwich panels are used in aeronautics, road vehicles, ships, and civil engineering. The mechanical properties of these composites are directly dependent on the properties of sandwich components and method of manufacturing. The paper presents some aspects of technology and its influence on mechanical properties of sandwich structure polymer composites. The sandwiches described in the paper were made by three different methods: hand lay-up, press method, and autoclave use. The samples of sandwiches were tested for failure caused by impact load. Sandwiches prepared in the same way were used for structural analysis of adhesive layer between panels and core. The results of research showed that the method of manufacturing, more precisely the pressure while forming sandwich panels, influences some mechanical properties of sandwich structured polymer composites such as flexural strength, impact strength, and compressive strength.

  6. International symposium on exotic nuclear structures. Book of abstracst

    International Nuclear Information System (INIS)

    2000-01-01

    The following topics were discussed at the meeting: Physics of weakly bound nuclei, neutron skin and halo; Evolution of shell structures for neutron-rich nuclei; Collective excitations in nuclei with exotic nuclear shapes; Cluster structures; Super- and hyperdeformed nuclei, exotic structures in the actinides; Superheavy elements; Towards understanding the structure of nucleons; New experimental techniques, facilities for radioactive beams. All abstracts (75 items) were submitted as full text to the INIS database. (R.P.)

  7. Cultural, Social, and Economic Capital Constructs in International Assessments: An Evaluation Using Exploratory Structural Equation Modeling

    Science.gov (United States)

    Caro, Daniel H.; Sandoval-Hernández, Andrés; Lüdtke, Oliver

    2014-01-01

    The article employs exploratory structural equation modeling (ESEM) to evaluate constructs of economic, cultural, and social capital in international large-scale assessment (LSA) data from the Progress in International Reading Literacy Study (PIRLS) 2006 and the Programme for International Student Assessment (PISA) 2009. ESEM integrates the…

  8. Spinning, structure and properties of PP/CNTs and PP/carbon black composite fibers

    Science.gov (United States)

    Marcincin, A.; Hricova, M.; Ujhelyiova, A.

    2014-08-01

    In this paper, the effect of the compatibilisers-dispersants and other nanofillers on melt spinning of the polypropylene (PP) composites, containing carbon nanotubes (CNTs), and carbon black pigment (CBP) has been investigated. Further, the structure and selected properties of composite fibers, such as mechanical and electrical have been studied. The results revealed, that percolation threshold for PP/CBP composite fibres was situated within the concentration of 15 - 20 wt%, what is several times higher than for PP/CNTs fibers.

  9. An addressable conducting network for autonomic structural health management of composite structures

    International Nuclear Information System (INIS)

    Takahashi, Kosuke; Park, Jong Se; Thomas Hahn, H

    2010-01-01

    The electrical resistance change method (ERCM) has long been an area of interest as an in-service health monitoring system. To apply the ERCM to existing structures, a new concept, the addressable conducting network (ACN), is proposed for autonomic structural health management of graphite/polymer composites. The ACN consists of two sets of conducting lines normal to each other, where one set resides on the top surface of the laminate and the other on the bottom surface. Damage can be detected by monitoring the resistance change 'through the laminate thickness' between two lines. By using a thermally mendable polymer as the matrix, the same conducting lines can be used to supply the electric current needed for resistive heating, thereby allowing the detected damage to be healed. As shown experimentally, the electrical resistance change method using an ACN distinguishes between laminates made of properly and improperly cured prepreg as well as revealing damage generated during three-point bending tests. Finite element analysis was performed to examine the feasibility of the ACN and indicated that the damage can be easily located from the spatial distribution of resistance changes and that the damaged area can be locally heated by supplying a large amount of current to selected conducting lines

  10. An addressable conducting network for autonomic structural health management of composite structures

    Science.gov (United States)

    Takahashi, Kosuke; Park, Jong Se; Hahn, H. Thomas

    2010-10-01

    The electrical resistance change method (ERCM) has long been an area of interest as an in-service health monitoring system. To apply the ERCM to existing structures, a new concept, the addressable conducting network (ACN), is proposed for autonomic structural health management of graphite/polymer composites. The ACN consists of two sets of conducting lines normal to each other, where one set resides on the top surface of the laminate and the other on the bottom surface. Damage can be detected by monitoring the resistance change 'through the laminate thickness' between two lines. By using a thermally mendable polymer as the matrix, the same conducting lines can be used to supply the electric current needed for resistive heating, thereby allowing the detected damage to be healed. As shown experimentally, the electrical resistance change method using an ACN distinguishes between laminates made of properly and improperly cured prepreg as well as revealing damage generated during three-point bending tests. Finite element analysis was performed to examine the feasibility of the ACN and indicated that the damage can be easily located from the spatial distribution of resistance changes and that the damaged area can be locally heated by supplying a large amount of current to selected conducting lines.

  11. Internal Flow Structures in Columnar Jointed Basalt from HREPPHÓLAR, Iceland

    Science.gov (United States)

    Mattsson, H. B.; Bosshard, S. A.; Hetenyi, G.; Almqvist, B.; Hirt, A. M.; Caricchi, L.; Caddick, M.

    2010-12-01

    Columnar jointed basalt from Hrepphólar in southern Iceland display spectacular internal structures when cut. These structures follow the overall orientation of the columns and display semi-circular to circular features when cross-cut. It was previously believed that these internal structures formed as a result of alteration due to circulation of meteoric water within the column-bounding fractures after emplacement. However, new field observations of viscous fingering within the columns and the fact that approximately 80% of the semi-circular features are found within the column whereas the remaining 20% are cut by the column-bounding fractures clearly shows that these internal structures must have formed prior to crack-propagation (and are thus primary features). Here we present the results of textural and petrological analyses through a cross-section of a column, in combination with magnetic susceptibility and anisotropy measurements of the same samples. The variation in textures and geochemistry can be attributed to the presence of diffuse banding caused by variations in the modal proportions of the main phenocryst phases (i.e., plagioclase, clinopyroxene, olivine and titanomagnetite/ilmenite). Orientation of plagioclase laths and titanomagnetite crystals (based on measurements in thin sections and AMS-measurements) are consistent with vertical flow alignment. Nowhere in the column can evidence for downwards flow be found (excluding the possibility of small-scale convection cells generating these features). It is proposed here, that the volume decrease associated with solidification (typically 10-15 vol.% for basaltic systems) and the increasing weight of the overlying crust results in upwelling of partially crystallized material into the centre of the columns. Preliminary numerical modeling indicates that the isotherms within individual columns become steeper with increasing depth in a lava flow (allowing for larger displacement distances). We propose that

  12. X-ray structure analysis of soil compositions

    International Nuclear Information System (INIS)

    Tillaev, T.; Kalonov, M.; Kuziev, Sh.; Khatamov, Sh.; Suvanov, M.

    1998-01-01

    The analytic characteristics of techniques developed to analyse soil structure by means of X-ray diffraction method are presented. Presence of 8 minerals in Fergana valley soils have been established. It is shown that X-ray structure analysis of soils gives rise to new original possibilities to determine not only their structure but also quantative content and type of chemical compound of element in soil. (author)

  13. Simulation of the structure and calculation of the thermal conductivity of napped composites

    International Nuclear Information System (INIS)

    Berezko, S.N.; Zarichnyak, Yu.P.; Korenev, P.A.

    1995-01-01

    We propose a model of the structure of a napped composite. Characteristic trends in the structure of the material are delineated, and the effective thermal conductivity of the model structure is calculated for these trends with allowance for conduction and radiation

  14. Fuzzy Fiber Sensors for Structural Composite Health Monitoring (Preprint)

    Science.gov (United States)

    2011-12-01

    fuzzy fibers to applied strain was measured in the following configurations: individual fiber, fiber tow, tow in matrix, and tow in laminated composite...panels, 12″ × 12″, were fabricated with IM7/977-2 prepreg unidirectional carbon fiber tape. Three panels each were prepared with unidirectional [0]8 or...were fabricated with 6″-long fuzzy fiber strain sensors embedded at the midpoint of the laminate plies. Eight straight-sided specimens (as shown in

  15. Microwave plasma CVD of NANO structured tin/carbon composites

    Science.gov (United States)

    Marcinek, Marek [Warszawa, PL; Kostecki, Robert [Lafayette, CA

    2012-07-17

    A method for forming a graphitic tin-carbon composite at low temperatures is described. The method involves using microwave radiation to produce a neutral gas plasma in a reactor cell. At least one organo tin precursor material in the reactor cell forms a tin-carbon film on a supporting substrate disposed in the cell under influence of the plasma. The three dimensional carbon matrix material with embedded tin nanoparticles can be used as an electrode in lithium-ion batteries.

  16. Report of International Workshop on tracing isotopic composition of past and present precipitation - opportunities for climate and water studies

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    The Workshop on Tracing Isotopic Composition of Past and Present Precipitation - Opportunities for Climate and Water Studies, was jointly organized by the World Meteorological Organization (WMO), the International Atomic Energy Agency (IAEA), Past Global Changes (PAGES) - a core project of the International Geosphere - Biosphere Programme (IGBP), and the International Association of Hydrological Sciences (IAHS). The Global Network ``Isotopes in Precipitation`` (GNIP) was initiated by IAEA in 1958 and became operational in 1961. The main objective was to collect systematic data on isotopic content of precipitation on a global scale and to establish temporal and spatial variations of environmental isotopes in precipitation. The network is now expected to serve additional purposes, namely as a benchmark for the interpretation of paleo-records, as a validation tool for Global Circulation Models, and for establishing large-scale regional (and continental-scale) waster balances. Furthermore, the structure of GNIP should be strengthened. This includes the build-up of: stations located close to major natural climatic archives (e.g. Greenland, mountain areas); stations which represent climatically sensitive areas (indicated by GCM`s and biome models). Isotope monitoring of river outflow from major continental basins should be initiated. This could be realized in co-operation with the UNEP/WHO Global Environmental Monitoring System-Water (GEMS-Water). The deuterium excess parameter ({delta}) is of particular importance in climate modelling and in the understanding of hydro-meteorological pathways. The use of the deuterium excess imposes strict requirements on the accuracy of deuterium and oxygen-18 analysis. A GNIP-based worldwide documentation of quality control regarding sampling, shipping and measurements is needed. The IAEA/WMO database and other isotope data sets should be included in the World Data Center A for palaeo-climatology. Refs, figs, tabs.

  17. Report of International Workshop on tracing isotopic composition of past and present precipitation - opportunities for climate and water studies

    International Nuclear Information System (INIS)

    1995-01-01

    The Workshop on Tracing Isotopic Composition of Past and Present Precipitation - Opportunities for Climate and Water Studies, was jointly organized by the World Meteorological Organization (WMO), the International Atomic Energy Agency (IAEA), Past Global Changes (PAGES) - a core project of the International Geosphere - Biosphere Programme (IGBP), and the International Association of Hydrological Sciences (IAHS). The Global Network ''Isotopes in Precipitation'' (GNIP) was initiated by IAEA in 1958 and became operational in 1961. The main objective was to collect systematic data on isotopic content of precipitation on a global scale and to establish temporal and spatial variations of environmental isotopes in precipitation. The network is now expected to serve additional purposes, namely as a benchmark for the interpretation of paleo-records, as a validation tool for Global Circulation Models, and for establishing large-scale regional (and continental-scale) waster balances. Furthermore, the structure of GNIP should be strengthened. This includes the build-up of: stations located close to major natural climatic archives (e.g. Greenland, mountain areas); stations which represent climatically sensitive areas (indicated by GCM's and biome models). Isotope monitoring of river outflow from major continental basins should be initiated. This could be realized in co-operation with the UNEP/WHO Global Environmental Monitoring System-Water (GEMS-Water). The deuterium excess parameter (δ) is of particular importance in climate modelling and in the understanding of hydro-meteorological pathways. The use of the deuterium excess imposes strict requirements on the accuracy of deuterium and oxygen-18 analysis. A GNIP-based worldwide documentation of quality control regarding sampling, shipping and measurements is needed. The IAEA/WMO database and other isotope data sets should be included in the World Data Center A for palaeo-climatology. Refs, figs, tabs

  18. Silicon carbide composites as fusion power reactor structural materials

    Energy Technology Data Exchange (ETDEWEB)

    Snead, L.L., E-mail: SneadLL@ORNL.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Nozawa, T. [Fusion Research and Development Directorate, Japan Atomic Energy Agency, 2-4 Shirakata Shirane, Tokai, Ibaraki 319-1195 (Japan); Ferraris, M. [Politecnico di Torino-DISMIC c. Duca degli Abruzzi, 24I-10129 Torino (Italy); Katoh, Y. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Shinavski, R. [Hypertherm HTC, 18411 Gothard St., Units A/B/C, Huntington Beach, CA 92648 (United States); Sawan, M. [University of Wisconsin, Madison 417 Engineering Research Building, 1500 Engineering Drive Madison, WI 53706-1687 (United States)

    2011-10-01

    Silicon carbide was first proposed as a low activation fusion reactor material in the mid 1970s. However, serious development of this material did not begin until the early 1990s, driven by the emergence of composite materials that provided enhanced toughness and an implied ability to use these typically brittle materials in engineering application. In the decades that followed, SiC composite system was successfully transformed from a poorly performing curiosity into a radiation stable material of sufficient maturity to be considered for near term nuclear and non-nuclear systems. In this paper the recent progress in the understanding and of basic phenomenon related to the use of SiC and SiC composite in fusion applications will be presented. This work includes both fundamental radiation effects in SiC and engineering issues such as joining and general materials properties. Additionally, this paper will briefly discuss the technological gaps remaining for the practical application of this material system in fusion power devices such as DEMO and beyond.

  19. Structural Analysis of Composite Laminates using Analytical and Numerical Techniques

    Directory of Open Access Journals (Sweden)

    Sanghi Divya

    2016-01-01

    Full Text Available A laminated composite material consists of different layers of matrix and fibres. Its properties can vary a lot with each layer’s or ply’s orientation, material property and the number of layers itself. The present paper focuses on a novel approach of incorporating an analytical method to arrive at a preliminary ply layup order of a composite laminate, which acts as a feeder data for the further detailed analysis done on FEA tools. The equations used in our MATLAB are based on analytical study code and supply results that are remarkably close to the final optimized layup found through extensive FEA analysis with a high probabilistic degree. This reduces significant computing time and saves considerable FEA processing to obtain efficient results quickly. The result output by our method also provides the user with the conditions that predicts the successive failure sequence of the composite plies, a result option which is not even available in popular FEM tools. The predicted results are further verified by testing the laminates in the laboratory and the results are found in good agreement.

  20. Students' Knowledge about the Internal Structure of Mice and Cockroaches in Their Environment

    Science.gov (United States)

    Kilic, Selda

    2013-01-01

    The aim of this study is to determine 9th class students knowledge about the internal structures of mice and cockroaches using drawings. Drawings of 122 students from the 9th class of a high school in the center of Konya about the internal structures of mice and cockroaches have been analyzed. Drawings were analyzed independently by two…