Sample records for sandwich construction

  1. Sandwich Construction Solar Structural Facets

    SciTech Connect

    Diver, R. B.; Grossman, J.W.

    1998-12-22

    Silver/glass mirrors have excellent optical properties but need a method of support in order to be used in concentrating solar thermal systems. In collaboration with the Cummins dish/Stirling development program, they started investigating sandwich construction as a way to integrate silver/glass mirrors into solar optical elements. In sandwich construction, membranes such as sheet metal or plastic are bonded to the front and back of a core (like a sandwich). For solar optical elements, a glass mirror is bonded to one of the membranes. This type of construction has the advantages of a high strength-to-weight ratio, and reasonable material and manufacturing cost. The inherent stiffness of sandwich construction mirror panels also facilitates large panels. This can have cost advantages for both the amount of hardware required as well as reduced installation and alignment costs. In addition, by incorporating the panels into the support structure reductions in the amount of structural support required are potentially possible.

  2. Transverse Shear Stiffness of a Chevron Folded Core Used in Sandwich Construction

    E-print Network

    Boyer, Edmond

    in aeronautics. When bending the sandwich panel, the skins are subjected to in-plane traction and compressionTransverse Shear Stiffness of a Chevron Folded Core Used in Sandwich Construction A. Leb´ee, K. Sab). Moreover, their transverse shear stiffness has been experimentally investigated by Kintscher et al. (2007

  3. Microstrip Antenna for SAR Application with Composite Sandwich Construction: Surface-antenna-structure Demonstration

    Microsoft Academic Search

    C. S. You; W. Hwang; H. C. Park; R. M. Lee; W. S. Park

    2003-01-01

    A 5.3 GHz microstrip antenna for use in synthetic aperture radar (SAR) systems was developed with a composite sandwich construction, using composite laminates, Nomex honeycomb and aluminum alloy. This is the surface-antenna-structure (SAS) for application to load-bearing structural surfaces. The design concept originated from a composite sandwich structure and a multi-layer microstrip antenna. Design, fabrication and validation of structural\\/electrical performances

  4. Mechanical behavior of sandwich panels with hollow AlSi tubes core construction Jian Xiong a

    E-print Network

    Vaziri, Ashkan

    ­Si alloy tubes as core construction and carbon fiber composite face sheets was designed. The hollow Al, their open-cell configuration allows heat exchange along the panel core, making them attractive candidates type of light weight sandwich panel with hollow Al­Si alloy tubes core is designed and manufactured

  5. Design and Fabrication of PLGA Sandwiched Cell\\/Fibrin Constructs for Complex Organ Regeneration

    Microsoft Academic Search

    Xiaohong Wang; Shaochun Sui; Yongnian Yan; Renji Zhang

    2010-01-01

    A poly(DL-lactic-co-glycolic acid) (PLGA) sandwich fibrinogen\\/ adipose stem cell (ADSC) construct was fabricated to generate smooth muscle tissue. The mechanical properties and ADSC compatibility of PLGA, poly(ethylene glycol-1,6-hexamethyl diisocyanate-caprolactone) i.e. polyurethane (PU), gelatin, alginate, and fibrin composites were evaluated for vascular smooth muscle tissue generation. Synthetic PLGA and PU combined with natural gelatin, alginate, and fibrin for strength and cell

  6. Material selection in sandwich beam construction Craig A. Steeves, Norman A. Fleck *

    E-print Network

    Fleck, Norman A.

    . The geometry of sandwich beams is optimised to minimise the mass for a required load bearing capacity in three, shear modulus Gc, compressive strength rc, and shear strength sc; for the face sheets, the pertinent collapse modes Core shear failure occurs when the shear strength of the core is exceeded, and the peak

  7. Highly efficient construction of oriented sandwich structures for surface-enhanced Raman scattering.

    PubMed

    Guo, Hongyun; Xu, Weiqing; Zhou, Ji; Xu, Shuping; Lombardi, John R

    2013-02-01

    The purpose of this study is to solve the problem of low achievement in fabricating sandwich surface-enhanced Raman scattering (SERS) substrates. We demonstrated a highly efficient sandwich structure by the oriented assembly of metal nanoparticles (NPs) on a periodic hexagonal array of metal nanoprisms with 1,4-benzenedithiol (1,4-BDT) as linkers. The metal nanoprism array was prepared by vacuum deposition of metal on a close-packed polystyrene nanosphere pre-patterned substrate. The metal nanoprism array presents different surface properties from the pits left from the removal of polystyrene nanospheres, which causes linkers to selectively adsorb on the metal nanoprism array and sequentially leads to the oriented immobilization of the second-layer metal NPs, avoiding mismatched orientation. These sandwich SERS substrates were characterized by extinction spectroscopy and atomic force microscopy and their enhancement activity was evaluated under different excitation wavelengths. The sandwich structure greatly increases the achievement of 'hot spots' to almost 100% of all the metal nanoprisms and enables a large amplification of SERS signals by a factor of ten. This method has the advantages of simplicity, high efficiency, high throughput, controllability and high reproducibility. It has significance in both the study of SERS substrates and the development of plasmonic devices. PMID:23299563

  8. sandwich structure

    NASA Astrophysics Data System (ADS)

    Chen, Lung-Chien; Hsu, Chih-Hung; Chan, Po-Shun; Zhang, Xiuyu; Huang, Cing-Jhih

    2014-08-01

    This study investigates the extent to which the TiO2/graphene/TiO2 sandwich structure improves the performance of dye-sensitized solar cells (DSSCs) over that of DSSCs with the traditional structure. Studies have demonstrated that the TiO2/graphene/TiO2 sandwich structure effectively enhances the open circuit voltage ( V oc), short-circuit current density ( J sc), and photoelectrical conversion efficiency ( ?) of DSSCs. The enhanced performance of DSSCs with the sandwich structure can be attributed to an increase in electron transport efficiency and in the absorption of light in the visible range. The DSSC with the sandwich structure in this study exhibited a V oc of 0.6 V, a high J sc of 11.22 mA cm-2, a fill factor (FF) of 0.58, and a calculated ? of 3.93%, which is 60% higher than that of a DSSC with the traditional structure.

  9. Multifunctional sandwich composites

    NASA Astrophysics Data System (ADS)

    Vaidya, Uday K.

    2003-10-01

    Sandwich composites find increasing use as flexural load bearing lightweight sub-elements in air/space vehicles, rail/ground transportation, marine and sporting goods. The core in these applications is usually balsa wood, foam or honeycomb with laminated carbon or glass facesheets. A limitation of traditional sandwich onfigurations is that the space in the core becomes inaccessible once the facesheets are bonded in place. Significant multi-functional benefits can be obtained by making either the facesheets or the core, space accessible. Multi-functionality is generally referred to as value added to the structure that enhances functions beyond traditional load bearing. Such functions may include sound/vibration damping, ability to route wires or embed sensors. The present work reviews recent work done in enhancing the functionality of the core by use of the space in the core. The damage created by impact to sandwich constructions is always a limiting issue in design. In the present work, low velocity impact (LVI) response of newer/multi-functional sandwich constructions has been studied. Concepts of increasing sandwich core functionality have been reported.

  10. Rare sandwich-type polyoxomolybdates constructed from Di-/tetra-nuclear transition-metal clusters and trivacant keggin germanomolybdate fragments.

    PubMed

    Li, Suzhi; Zhao, Junwei; Ma, Pengtao; Du, Juan; Niu, Jingyang; Wang, Jingping

    2009-10-19

    Two types of rare sandwich-type germanomolybdates [Na(12)(H(2)O)(36)][Cu(2)(beta-Y-GeMo(9)O(33))(2)].3H(2)O (1), [N(CH(3))(4)](4) [Na(6)(H(2)O)(24)][Cr(2)(beta-Y-GeMo(9)O(33))(2)].7H(2)O (2), and [Na(11)(H(2)O)(25)]H[M(4)(H(2)O)(2)(alpha-B-GeMo(9)O(34))(2)].6H(2)O (M = Ni(II) for 3, M = Mn(II) for 4 and M = Co(II) for 5) have been synthesized and characterized by elemental analyses, ICP spectra, IR spectroscopy, UV spectroscopy, thermogravimetry (TG) analyses (for 1-3), X-ray photoelectron spectroscopy (XPS) (for 1 and 3), X-ray powder diffraction (XRPD) (for 1 and 3) and single-crystal X-ray diffraction. To our knowledge, 1-5 represent the first sandwich-type germanomolybdates containing both {beta-Y-GeMo(9)O(33)}/{alpha-B-GeMo(9)O(34)} fragments and transition-metal clusters. Interestingly, 1 and 2 display the rare dinuclear transition-metal substituted sandwich-type structures with unusual trivacant {beta-Y-GeMo(9)O(33)} germanomolybdate units whereas 3-5 exhibit the first tetranuclear transition-metal substituted sandwich-type structures with familiar trivacant {alpha-B-GeMo(9)O(34)} germanomolybdate units. Surface photovoltage spectroscopy (SPS) and electric field induced surface photovoltage spectroscopy (EFISPS) measurements reveal that 1 and 3 bear the behavior of the n-type semiconductor. Magnetic measurements indicate 1 and 3 demonstrate antiferromagnetic exchange interactions and ferromagnetic exchange interactions, respectively. PMID:19769384

  11. Composite sandwich construction with syntactic foam core - A practical assessment of post-impact damage and residual strength

    NASA Technical Reports Server (NTRS)

    Hiel, C.; Dittman, D.; Ishai, O.

    1993-01-01

    An account is given of an inspection method that has been successfully used to assess the postimpact damage and residual strength of syntactic (glass microspheres in epoxy matrix) foam-core sandwich panels with hybrid (carbon and glass fiber-reinforced) composite skins, which inherently possess high damage tolerance. SEM establishes that the crushing of the microspheres is responsible for the absorption of most of the impact energy. Damage tolerance is a function of the localization of damage by that high impact energy absorption.

  12. Power Sandwich: An integration technology for manufacturability

    Microsoft Academic Search

    J. A. Ferreira; J. Popovic?-Gerber; I. Josifovic?

    2010-01-01

    This paper presents a novel power electronics construction technology for surface mount technology (SMT) automated manufacturing of power converters- Power Sandwich. The Power Sandwich manufacturing method employs new x-dimension components, having the same height (x) and double sided SMT electrical terminations. The components are stacked between planar substrates and can be soldered on both, top and bottom sides using the

  13. Design of Sandwich Structures

    E-print Network

    Petras, Achilles

    Failure modes for sandwich beams of GFRP laminate skins and Nomex honeycomb core are investigated. Theoretical models using honeycomb mechanics and classical beam theory are described. A failure mode map for loading under 3-point bending...

  14. Graphene veils and sandwiches.

    PubMed

    Yuk, Jong Min; Kim, Kwanpyo; Alemn, Benjamn; Regan, William; Ryu, Ji Hoon; Park, Jungwon; Ercius, Peter; Lee, Hyuck Mo; Alivisatos, A Paul; Crommie, Michael F; Lee, Jeong Yong; Zettl, Alex

    2011-08-10

    We report a new and highly versatile approach to artificial layered materials synthesis which borrows concepts of molecular beam epitaxy, self-assembly, and graphite intercalation compounds. It readily yields stacks of graphene (or other two-dimensional sheets) separated by virtually any kind of "guest" species. The new material can be "sandwich like", for which the guest species are relatively closely spaced and form a near-continuous inner layer of the sandwich, or "veil like", where the guest species are widely separated, with each guest individually draped within a close-fitting, protective yet atomically thin graphene net or veil. The veils and sandwiches can be intermixed and used as a two-dimensional platform to control the movements and chemical interactions of guest species. PMID:21770385

  15. SPECIALTY SANDWICHES ADDITIONS & SIDES

    E-print Network

    Mills, Allen P.

    , Italian Squash, Red Bell Peppers, Red Onion, and Tomatoes, topped with Feta Cheese, Candied Pecans with Spinach and Mushrooms, topped with Spinach, Roasted Red Bell Pepper, Grilled Onions, and a Smokey Aioli CUP BOWL CUP OF SOUP & SALAD299 419 519 CHILI MARINATED PORK SANDWICH...799 Avocado, Pepper Jack

  16. "If They're the Customer, I'm the Meat in the Sandwich": An Exploration of Tertiary Teachers' Metaphorical Constructions of Teaching

    ERIC Educational Resources Information Center

    Emerson, Lisa; Mansvelt, Juliana

    2014-01-01

    Metaphors are a primary influence on the way we perceive and construct our world; they are also a way of revealing beliefs and attitudes that might otherwise be difficult to identify. Furthermore, metaphor has been found to be an effective way of shifting people's beliefs, attitudes and behaviour. This paper details the findings of a pilot

  17. Structural Analysis of Sandwich Foam Panels

    SciTech Connect

    Kosny, Jan [ORNL; Huo, X. Sharon [Tennessee Technological University

    2010-04-01

    The Sandwich Panel Technologies including Structural Insulated Panels (SIPs) can be used to replace the conventional wooden-frame construction method. The main purpose of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC and SGI Venture, Inc. was to design a novel high R-value type of metal sandwich panelized technology. This CRADA project report presents design concept discussion and numerical analysis results from thermal performance study of this new building envelope system. The main objective of this work was to develop a basic concept of a new generation of wall panel technologies which will have R-value over R-20 will use thermal mass to improve energy performance in cooling dominated climates and will be 100% termite resistant. The main advantages of using sandwich panels are as follows: (1) better energy saving structural panels with high and uniform overall wall R-value across the elevation that could not be achieved in traditional walls; and (2) reducing the use of raw materials or need for virgin lumber. For better utilization of these Sandwich panels, engineers need to have a thorough understanding of the actual performance of the panels and system. Detailed analysis and study on the capacities and deformation of individual panels and its assembly have to be performed to achieve that goal. The major project activity was to conduct structural analysis of the stresses, strains, load capacities, and deformations of individual sandwich components under various load cases. The analysis simulated the actual loading conditions of the regular residential building and used actual material properties of the steel facings and foam.

  18. Facesheet Delamination of Composite Sandwich Materials at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Odegard, Gregory M.; Herring, Helen M.

    2003-01-01

    The next generation of space transportation vehicles will require advances in lightweight structural materials and related design concepts to meet the increased demands on performance. One potential source for significant structural weight reduction is the replacement of traditional metallic cryogenic fuel tanks with new designs for polymeric matrix composite tanks. These new tank designs may take the form of thin-walled sandwich constructed with lightweight core and composite facesheets. Life-time durability requirements imply the materials must safely carry pressure loads, external structural loads, resist leakage and operate over an extremely wide temperature range. Aside from catastrophic events like tank wall penetration, one of the most likely scenarios for failure of a tank wall of sandwich construction is the permeation of cryogenic fluid into the sandwich core and the subsequent delamination of the sandwich facesheet due to the build-up of excessive internal pressure. The research presented in this paper was undertaken to help understand this specific problem of core to facesheet delamination in cryogenic environments and relate this data to basic mechanical properties. The experimental results presented herein provide data on the strain energy release rate (toughness) of the interface between the facesheet and the core of a composite sandwich subjected to simulated internal pressure. A unique test apparatus and associated test methods are described and the results are presented to highlight the effects of cryogenic temperature on the measured material properties.

  19. Indentation resistance of sandwich beams

    Microsoft Academic Search

    A. Petras; M. P. F. Sutcliffe

    1999-01-01

    High-order sandwich beam theory is used to model the local deformation under the central indentor for sandwich beams loaded under three-point bending. `High-order' refers to the non-linear variations of in-plane and vertical displacements through the height of the core which the model incorporates. The analysis is elastic, which is appropriate to describe the beam response up to peak load for

  20. High temperature structural sandwich panels

    Microsoft Academic Search

    Christos G. Papakonstantinou

    2003-01-01

    High strength composites are being used for making lightweight structural panels that are being employed in aerospace, naval and automotive structures. Recently, there is renewed interest in use of these panels. The major problem of most commercial available sandwich panels is the fire resistance. A recently developed inorganic matrix is investigated for use in cases where fire and high temperature

  1. Tuna Apple Salad Sandwiches Ingredients

    E-print Network

    Liskiewicz, Maciej

    Tuna Apple Salad Sandwiches Ingredients: 6 1/2 ounces tuna in water, canned 1 stalk celery 1 apple and chop in small pieces. Wash and cut apple in half and in half again. Cut out core and chop into small pieces. 3. Add celery and apple to tuna. Stir well. 4. Add mayonnaise and lemon juice. Stir well. 5

  2. Cellular Truss Core Sandwich Structures

    Microsoft Academic Search

    David J. Sypeck

    2005-01-01

    Sandwich structures with open cell truss cores are a relatively new class of multifunctional material systems that can be made using affordable deformation, assembly and joining processes. A variety of cellular core architectures have recently been made from wrought metal alloys using inexpensive textile and perforated sheet methods. Here, the design, fabrication and properties for these types of structures is

  3. High temperature structural sandwich panels

    NASA Astrophysics Data System (ADS)

    Papakonstantinou, Christos G.

    High strength composites are being used for making lightweight structural panels that are being employed in aerospace, naval and automotive structures. Recently, there is renewed interest in use of these panels. The major problem of most commercial available sandwich panels is the fire resistance. A recently developed inorganic matrix is investigated for use in cases where fire and high temperature resistance are necessary. The focus of this dissertation is the development of a fireproof composite structural system. Sandwich panels made with polysialate matrices have an excellent potential for use in applications where exposure to high temperatures or fire is a concern. Commercial available sandwich panels will soften and lose nearly all of their compressive strength temperatures lower than 400C. This dissertation consists of the state of the art, the experimental investigation and the analytical modeling. The state of the art covers the performance of existing high temperature composites, sandwich panels and reinforced concrete beams strengthened with Fiber Reinforced Polymers (FRP). The experimental part consists of four major components: (i) Development of a fireproof syntactic foam with maximum specific strength, (ii) Development of a lightweight syntactic foam based on polystyrene spheres, (iii) Development of the composite system for the skins. The variables are the skin thickness, modulus of elasticity of skin and high temperature resistance, and (iv) Experimental evaluation of the flexural behavior of sandwich panels. Analytical modeling consists of a model for the flexural behavior of lightweight sandwich panels, and a model for deflection calculations of reinforced concrete beams strengthened with FRP subjected to fatigue loading. The experimental and analytical results show that sandwich panels made with polysialate matrices and ceramic spheres do not lose their load bearing capability during severe fire exposure, where temperatures reach several hundred degrees Centigrade. Hence the material has excellent potential for various types of applications. The analytical predictions from both models provide reasonably accurate results. Glass, AR-glass, carbon and Nicalon tows and carbon fabrics could be successfully used as skin reinforcements increasing the flexural stiffness and strength of the core. No occurrence of fiber delamination was observed.

  4. Development of biobased sandwich structures for mass transit application

    NASA Astrophysics Data System (ADS)

    Munusamy, Sethu Raaj

    Efforts to increase the biobased content in sandwich composites are being investigated to reduce the dependence on synthetically produced or mined, energy-intensive materials for numerous composite applications. Vegetable oil-based polyurethane foams are gaining recognition as good substitutes for synthetic counter parts while utilizing bast fiber to replace fiberglass is also gaining credence. In this study, soy oil-based polyurethane foam was evaluated as a core in a sandwich construction with facesheets of hybridized kenaf and E-glass fibers in a vinyl ester resin matrix to replace traditionally used plywood sheeting on steel frame for mass transit bus flooring systems. As a first step towards implementation, the static performance of the biobased foam was compared to 100% synthetic foam. Secondly, biobased sandwich structures were processed and their static performance was compared to plywood. The biobased sandwich composites designed and processed were shown to hold promise towards replacing plywood for bus flooring applications by displaying an increase of 130% for flexural strength and 135% for flexural modulus plus better indentation values.

  5. Radially sandwiched cylindrical piezoelectric transducer

    NASA Astrophysics Data System (ADS)

    Lin, Shuyu; Fu, Zhiqiang; Zhang, Xiaoli; Wang, Yong; Hu, Jing

    2013-01-01

    A new type of radially sandwiched piezoelectric short cylindrical transducer is developed and its radial vibration is studied. The transducer is composed of a solid metal disk, a radially polarized piezoelectric ceramic short tube and a metal tube. The radial vibrations of the solid metal disk, the radially polarized piezoelectric tube and the metal tube are analyzed and their electromechanical equivalent circuits are introduced. Based on the mechanical boundary conditions among the metal disk, the piezoelectric tube and the metal tube, a three-port electromechanical equivalent circuit for the radially sandwiched transducer is obtained and the frequency equation is given. The theoretical relationship of the resonance and anti-resonance frequencies and the effective electromechanical coupling coefficient with the geometrical dimensions is analyzed. The radial vibration of the sandwiched transducer is simulated by using two different numerical methods. It is shown that the analytical resonance and anti-resonance frequencies are in good agreement with the numerically simulated results. The transducer is expected to be used in piezoelectric resonators, actuators and ultrasonic radiators in ultrasonic and underwater sound applications.

  6. Informal Caregiving: Dilemmas of Sandwiched Caregivers

    Microsoft Academic Search

    Rose M. Rubin; Shelley I. White-Means

    2009-01-01

    Increased demand will intensify pressures for informal caregiving, especially for sandwiched caregivers. Using 1999, National\\u000a Long Term Care Survey data, we contrasted socio-demographic statistics, care environments, activities of daily living (ADL)\\u000a and instrumental activities of daily living (IADL) assistance, life quality, and employment burden of sandwiched versus non-sandwiched\\u000a parental caregivers. Regression analysis explored variables influencing caregiving hours, employment accommodation, stress,

  7. Compressive strength after blast of sandwich composite materials

    PubMed Central

    Arora, H.; Kelly, M.; Worley, A.; Del Linz, P.; Fergusson, A.; Hooper, P. A.; Dear, J. P.

    2014-01-01

    Composite sandwich materials have yet to be widely adopted in the construction of naval vessels despite their excellent strength-to-weight ratio and low radar return. One barrier to their wider use is our limited understanding of their performance when subjected to air blast. This paper focuses on this problem and specifically the strength remaining after damage caused during an explosion. Carbon-fibre-reinforced polymer (CFRP) composite skins on a styreneacrylonitrile (SAN) polymer closed-cell foam core are the primary composite system evaluated. Glass-fibre-reinforced polymer (GFRP) composite skins were also included for comparison in a comparable sandwich configuration. Full-scale blast experiments were conducted, where 1.61.3?m sized panels were subjected to blast of a HopkinsonCranz scaled distance of 3.02?m?kg?1/3, 100?kg TNT equivalent at a stand-off distance of 14?m. This explosive blast represents a surface blast threat, where the shockwave propagates in air towards the naval vessel. Hopkinson was the first to investigate the characteristics of this explosive air-blast pulse (Hopkinson 1948 Proc. R. Soc. Lond. A 89, 411413 (doi:10.1098/rspa.1914.0008)). Further analysis is provided on the performance of the CFRP sandwich panel relative to the GFRP sandwich panel when subjected to blast loading through use of high-speed speckle strain mapping. After the blast events, the residual compressive load-bearing capacity is investigated experimentally, using appropriate loading conditions that an in-service vessel may have to sustain. Residual strength testing is well established for post-impact ballistic assessment, but there has been less research performed on the residual strength of sandwich composites after blast. PMID:24711494

  8. Compressive strength after blast of sandwich composite materials.

    PubMed

    Arora, H; Kelly, M; Worley, A; Del Linz, P; Fergusson, A; Hooper, P A; Dear, J P

    2014-05-13

    Composite sandwich materials have yet to be widely adopted in the construction of naval vessels despite their excellent strength-to-weight ratio and low radar return. One barrier to their wider use is our limited understanding of their performance when subjected to air blast. This paper focuses on this problem and specifically the strength remaining after damage caused during an explosion. Carbon-fibre-reinforced polymer (CFRP) composite skins on a styrene-acrylonitrile (SAN) polymer closed-cell foam core are the primary composite system evaluated. Glass-fibre-reinforced polymer (GFRP) composite skins were also included for comparison in a comparable sandwich configuration. Full-scale blast experiments were conducted, where 1.61.3?m sized panels were subjected to blast of a Hopkinson-Cranz scaled distance of 3.02?m?kg(-1/3), 100?kg TNT equivalent at a stand-off distance of 14?m. This explosive blast represents a surface blast threat, where the shockwave propagates in air towards the naval vessel. Hopkinson was the first to investigate the characteristics of this explosive air-blast pulse (Hopkinson 1948 Proc. R. Soc. Lond. A 89, 411-413 (doi:10.1098/rspa.1914.0008)). Further analysis is provided on the performance of the CFRP sandwich panel relative to the GFRP sandwich panel when subjected to blast loading through use of high-speed speckle strain mapping. After the blast events, the residual compressive load-bearing capacity is investigated experimentally, using appropriate loading conditions that an in-service vessel may have to sustain. Residual strength testing is well established for post-impact ballistic assessment, but there has been less research performed on the residual strength of sandwich composites after blast. PMID:24711494

  9. Facesheet Wrinkling in Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Ley, Robert P.; Lin, Weichuan; Mbanefo, Uy

    1999-01-01

    The purpose of this paper is to provide a concise summary of the state-of-the-art for the analysis of the facesheet wrinkling mode of failure in sandwich structures. This document is not an exhaustive review of the published research related to facesheet wrinkling. Instead, a smaller number of key papers are reviewed in order to provide designers and analysts with a working understanding of the state-of-the-art. Designers and analysts should use this survey to guide their judgement when deciding which one of a wide variety of available facesheet wrinkling design formulas is applicable to a specific design problem.

  10. Metal sandwich plates optimized for pressure impulses

    Microsoft Academic Search

    John W. Hutchinson; Zhenyu Xue

    2005-01-01

    Survival of a plate against an intense, short duration impulsive loading requires the circumvention of failure modes, including those associated with excessive overall deflection and shear-off at supports and webs. All-metal sandwich plates have distinct advantages over comparable weight monolithic plates, especially for intense water loadings. A recently developed mechanics of dynamically loaded sandwich plates by N. A. Fleck and

  11. Development and Evaluation of Stitched Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Stanley, Larry E.; Adams, Daniel O.; Reeder, James R. (Technical Monitor)

    2001-01-01

    This study explored the feasibility and potential benefits provided by the addition of through-the-thickness reinforcement to sandwich structures. Through-the-thickness stitching is proposed to increase the interlaminar strength and damage tolerance of composite sandwich structures. A low-cost, out-of-autoclave processing method was developed to produce composite sandwich panels with carbon fiber face sheets, a closed-cell foam core, and through-the-thickness Kevlar stitching. The sandwich panels were stitched in a dry preform state, vacuum bagged, and infiltrated using Vacuum Assisted Resin Transfer Molding (VARTM) processing. For comparison purposes, unstitched sandwich panels were produced using the same materials and manufacturing methodology. Test panels were produced initially at the University of Utah and later at NASA Langley Research Center. Four types of mechanical tests were performed: flexural testing, flatwise tensile testing, core shear testing, and edgewise compression testing. Drop-weight impact testing followed by specimen sectioning was performed to characterize the damage resistance of stitched sandwich panels. Compression after impact (CAI) testing was performed to evaluate the damage tolerance of the sandwich panels. Results show significant increases in the flexural stiffness and strength, out-of-plane tensile strength, core shear strength, edgewise compression strength, and compression-after-impact strength of stitched sandwich structures.

  12. Indentation failure analysis of sandwich beams

    Microsoft Academic Search

    A Petras; M. P. F Sutcliffe

    2000-01-01

    Failure of sandwich honeycomb structures under indentation loading is considered. A failure criterion for Nomex honeycombs subjected to combined compressive and shear stresses is determined using biaxial tests. By combining this with a theoretical calculation of the stress distribution in the core due to indentation loading, found from a high-order sandwich beam theory (HOSBT), the indentation failure load of the

  13. Puncture black hole initial data in the conformal thin-sandwich formalism

    E-print Network

    Thomas W. Baumgarte

    2011-08-17

    We revisit the construction of puncture black hole initial data in the conformal thin-sandwich decomposition of Einstein's constraint equations. It has been shown previously that this approach cannot yield quasiequilibrium wormhole data, which connect two asymptotically flat spatial infinities. This argument does not apply to trumpet data, which connect the spatial infinity in one universe with the future timelike infinity of another. As a numerical demonstration we present results for a single boosted trumpet-puncture black holes, constructed in the original version of the conformal thin-sandwich formalism.

  14. Feedback sandwiches affect perceptions but not performance.

    PubMed

    Parkes, Jay; Abercrombie, Sara; McCarty, Teresita

    2013-08-01

    The feedback sandwich technique-make positive comments; provide critique; end with positive comments-is commonly recommended to feedback givers despite scant evidence of its efficacy. These two studies (N=20; N=350) of written peer feedback with third-year medical students on clinical patient note-writing assignments indicate that students think feedback sandwiches positively impact subsequent performance when there is no evidence that they do. The effort necessary to produce feedback sandwiches and students' unwarranted confidence in their performance impact have implications for teaching about how to give feedback. PMID:22581568

  15. Le calcul des structures sandwich par lments finis

    E-print Network

    Paris-Sud XI, Université de

    comparés aux solutions analytiques et EF d'ANSYS. ABSTRACT Sandwich materials, which are still widely used in static linear analysis of sandwich beams. Comparisons are made with analytical and ANSYS FE results. SANDWICH - STATIQUE - CONTRAINTES D'INTERFACE - ANSYS - POST-TRAITEMENT SANDWICH - STATIC ANALYSIS

  16. Precast concrete sandwich panels subjected to impact loading

    NASA Astrophysics Data System (ADS)

    Runge, Matthew W.

    Precast concrete sandwich panels are a relatively new product in the construction industry. The design of these panels incorporates properties that allow for great resilience against temperature fluctuation as well as the very rapid and precise construction of facilities. The concrete sandwich panels investigated in this study represent the second generation of an ongoing research and development project. This second generation of panels have been engineered to construct midsized commercial buildings up to three stories in height as well as residential dwellings. The panels consist of a double-tee structural wythe, a foam core and a fascia wythe, joined by shear connectors. Structures constructed from these panels may be subjected to extreme loading including the effects of seismic and blast loading in addition to wind. The aim of this work was to investigate the behaviour of this particular sandwich panel when subjected to structural impact events. The experimental program consisted of fourteen concrete sandwich panels, five of which were considered full-sized specimens (2700 mm X 1200mm X 270 mm) and nine half-sized specimens (2700mm X 600mm X 270 mm) The panels were subjected to impact loads from a pendulum impact hammer where the total energy applied to the panels was varied by changing the mass of the hammer. The applied loads, displacements, accelerations, and strains at the mid-span of the panel as well as the reaction point forces were monitored during the impact. The behaviour of the panels was determined primarily from the experimental results. The applied loads at low energy levels that caused little to no residual deflection as well as the applied loads at high energy levels that represent catastrophic events and thus caused immediate failure were determined from an impact on the structural and the fascia wythes. Applied loads at intermediate energy levels representing extreme events were also used to determine whether or not the panels could withstand multiple impacts. It was shown that panels impacted on the fascia wythe are capable of withstanding multiple impacts of energy levels in excess of 16 000 J while panels that were impacted on the structural wythe are capable of resisting a single impact delivering an energy level of 10 000 J or multiple impacts from an energy level of 5 000 J. A Single Degree of Freedom (SDOF) model was developed to predict the maximum deflection of the panels and it provided a good approximation of the deflection observed during the experimental program. A high degree of composite action between the two wythes was determined to exist from the results of high speed video imaging and through SDOF modelling.

  17. Shear lag in truss core sandwich beams

    E-print Network

    Roberts, Ryan (Ryan M.)

    2005-01-01

    An experimental study was conducted to investigate the possible influence of shear lag in the discrepancy between the theoretical and measured stiffness of truss core sandwich beams. In previous studies, the measured values ...

  18. Local slamming impact of sandwich composite hulls

    Microsoft Academic Search

    Z. Qin; R. C. Batra

    2009-01-01

    We develop a hydroelastic model based on a {3,2}-order sandwich composite panel theory and Wagners water impact theory for investigating the fluidstructure interaction during the slamming process. The sandwich panel theory incorporates the transverse shear and the transverse normal deformations of the core, while the face sheets are modeled with the Kirchhoff plate theory. The structural model has been validated

  19. Conditional Logistic Regression with Sandwich Estimators

    Cancer.gov

    This IBM PC program performs conditional logistic regression on clustered data and calculates a sandwich ("robust") estimator of the covariance of the regression coefficients. Use of the sandwich estimator allows appropriate inferences for either fixed or random effects across clusters. The program uses two modifications to the usual Wald test to adjust for cases where some parameters are estimated from a small number of clusters.

  20. Experimental study of acoustical characteristics of honeycomb sandwich structures

    NASA Astrophysics Data System (ADS)

    Peters, Portia Renee

    Loss factor measurements were performed on sandwich panels to determine the effects of different skin and core materials on the acoustical properties. Results revealed inserting a viscoelastic material in the core's mid-plane resulted in the highest loss factor. Panels constructed with carbon-fiber skins exhibited larger loss factors than glass-fiber skins. Panels designed to achieve subsonic wave speed did not show a significant increase in loss factor above the coincidence frequency. The para-aramid core had a larger loss factor value than the meta-aramid core. Acoustic absorption coefficients were measured for honeycomb sandwiches designed to incorporate multiple sound-absorbing devices, including Helmholtz resonators and porous absorbers. The structures consisted of conventional honeycomb cores filled with closed-cell polyurethane foams of various densities and covered with perforated composite facesheets. Honeycomb cores filled with higher density foam resulted in higher absorption coefficients over the frequency range of 50 -- 1250 Hz. However, this trend was not observed at frequencies greater than 1250 Hz, where the honeycomb filled with the highest density foam yielded the lowest absorption coefficient among samples with foam-filled cores. The energy-recycling semi-active vibration suppression method (ERSA) was employed to determine the relationship between vibration suppression and acoustic damping for a honeycomb sandwich panel. Results indicated the ERSA method simultaneously reduced the sound transmitted through the panel and the panel vibration. The largest reduction in sound transmitted through the panel was 14.3% when the vibrations of the panel were reduced by 7.3%. The influence of different design parameters, such as core density, core material, and cell size on wave speeds of honeycomb sandwich structures was experimentally analyzed. Bending and shear wave speeds were measured and related to the transmission loss performance for various material configurations. The shear modulus of the core showed maximum influence on the wave speeds of the samples, while cell size did not have a significant influence on wave speeds or on transmission loss. Skin material affected wave speeds only in the pure bending regime. Honeycomb sandwich structures with a subsonic core and thus reduced wave speed showed increased transmission loss compared to samples without a subsonic core.

  1. Experimental study of acoustical behavior of flat honeycomb sandwich panel

    NASA Astrophysics Data System (ADS)

    Rajaram, Shankar

    Honeycomb (HC) sandwich composites have lightweight and excellent mechanical properties, but have poor acoustic properties. This work was done to improve the acoustical performance of HC sandwich composites used in airplane floors. Transmission loss (TL) is one of the metrics used to assess acoustical performance of HC sandwiches and requires a TL suite. A small-scale sound transmission loss (TL) test facility was designed, constructed and qualified to conduct the experiments. TL measurements were made using the sound intensity technique based on ASTM. The small-scale facility was qualified between 315 Hz and 10 KHz, and the results of test panels were compared to results from two full-scale accredited labs. TL measured at the small-scale facility yielded reliable, relative comparisons for flat, HC panels. HC panel bending waves are characterized by three frequency regimes---total panel bending, core shear, and individual skin bending---that are controlled by panel geometry, panel mass and elastic properties of the core and the skins. Superior TL performance can be achieved by designing HC panels with significantly subsonic shear wave speed that delays the onset of coincidence frequency. The influence of different commercial HC sandwich design parameters, such as core density, core material, cell size, and cell structure, on TL was investigated. Frequency responses of TL for these panels were inferior. Supersonic core shear wave speed was identified as the reason for inferior acoustic performance. So three classes of panels with different core shear wave speeds---subsonic, transonic, and supersonic---were fabricated and compared for TL. Panels with subsonic and transonic core shear wave speeds showed improved acoustic performance than their supersonic counterparts. Also, optimization studies on panels with subsonic wave speeds showed that the mechanical performance of subsonic and transonic panel designs is generally low, but can be improved when accompanied by weight increase. Comparison of TL performance was made between panels with honeycomb cores made of p-aramid and m-aramid. The stiffer p-aramid HC cores improved the TL above coincidence frequency compared to m-aramid cores. The reason for improved TL at higher frequencies was the lowering of modal density for p-aramid HC cores. Lightweight noise control treatments for honeycomb sandwich panels were explored by adding a gas barrier layer to the panel on the incident side. (Abstract shortened by UMI.)

  2. Structural performance of near-optimal sandwich panels with corrugated cores

    Microsoft Academic Search

    L. Valdevit; Z. Wei; C. Mercer; F. W. Zok; A. G. Evans

    2005-01-01

    An experimental and computational study of the bending response of steel sandwich panels with corrugated cores in both transverse and longitudinal loading orientations has been performed. Panel designs were chosen on the basis of failure mechanism maps, constructed using analytic models for failure initiation. The assessment affirms that the ana- lytic models provide accurate predictions when failure initiation is controlled

  3. Radiant heating tests of several liquid metal heat-pipe sandwich panels

    NASA Technical Reports Server (NTRS)

    Camarda, C. J.; Basiulis, A.

    1983-01-01

    Integral heat pipe sandwich panels, which synergistically combine the thermal efficiency of heat pipes and the structural efficiency of honeycomb sandwich construction, were conceived as a means of alleviating thermal stress problems in the Langley Scramjet Engine. Test panels which utilized two different wickable honeycomb cores, facesheets with screen mesh sintered to the internal surfaces, and a liquid metal working fluid (either sodium or potassium) were tested by radiant heating at various heat load levels. The heat pipe panels reduced maximum temperature differences by 31 percent with sodium working fluid and 45 percent with potassium working fluid. Results indicate that a heat pipe sandwich panel is a potential, simple solution to the engine thermal stress problem. Other interesting applications of the concept include: cold plates for electronic component and circuit card cooling, radiators for large space platforms, low distortion large area structures (e.g., space antennas) and laser mirrors.

  4. Mechanical and thermal buckling analysis of rectangular sandwich panels under different edge conditions

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    1994-01-01

    The combined load (mechanical or thermal load) buckling equations were established for orthotropic rectangular sandwich panels under four different edge conditions by using the Rayleigh-Ritz method of minimizing the total potential energy of a structural system. Two-dimensional buckling interaction curves and three-dimensional buckling interaction surfaces were constructed for high-temperature honeycomb-core sandwich panels supported under four different edge conditions. The interaction surfaces provide overall comparison of the panel buckling strengths and the domains of symmetrical and antisymmetrical buckling associated with the different edge conditions. In addition, thermal buckling curves of these sandwich panels are presented. The thermal buckling conditions for the cases with and without thermal moments were found to be identical for the small deformation theory.

  5. Sandwich Panels Evaluated With Ultrasonic Spectroscopy

    NASA Technical Reports Server (NTRS)

    Cosgriff, Laura M.

    2004-01-01

    Enhanced, lightweight material systems, such as 17-4PH stainless steel sandwich panels are being developed for use as fan blades and fan containment systems for next-generation engines. The bond strength between the core and face sheets is critical in maintaining the structural integrity of the sandwich structure. To improve the inspection and production of these systems, researchers at the NASA Glenn Research Center are using nondestructive evaluation (NDE) techniques, such as ultrasonic spectroscopy, to evaluate the brazing quality between the face plates and the metallic foam core. The capabilities and limitations of a swept-frequency approach to ultrasonic spectroscopy were evaluated with respect to these sandwich structures. This report discusses results from three regions of a sandwich panel representing different levels of brazing quality between the outer face plates and a metallic foam core. Each region was investigated with ultrasonic spectroscopy. Then, on the basis of the NDE results, three shear specimens sectioned from the sandwich panel to contain each of these regions were mechanically tested.

  6. Long-term hygrothermal effects on damage tolerance of hybrid composite sandwich panels

    NASA Technical Reports Server (NTRS)

    Ishai, Ori; Hiel, Clement; Luft, Michael

    1995-01-01

    A sandwich construction, composed of hybrid carbon-glass fiber-reinforced plastic skins and a syntactic foam core, was selected as the design concept for a wind tunnel compressor blade application, where high damage tolerance and durability are of major importance. Beam specimens were prepared from open-edge and encapsulated sandwich panels which had previously been immersed in water at different temperatures for periods of up to about two years in the extreme case. Moisture absorption and strength characteristics, as related to time of exposure to hygrothermal conditions, were evaluated for the sandwich specimens and their constituents (skins and foam). After different exposure periods, low-velocity impact damage was inflicted on most sandwich specimens and damage characteristics were related to impact energy. Eventually, the residual compressive strengths of the damaged (and undamaged) beams were determined flexurally. Test results show that exposure to hygrothermal conditions leads to significant strength reductions for foam specimens and open-edge sandwich panels, compared with reference specimens stored at room temperature. In the case of skin specimens and for beams prepared from encapsulated sanwich panels that had previously been exposed to hygrothermal conditions, moisture absorption was found to improve strength as related to the reference case. The beneficial effect of moisture on skin performance was, however, limited to moisture contents below 1% (at 50 C and lower temperatures). Above this moisture level and at higher temperatures, strength degradation of the skin seems to prevail.

  7. Analysis of Stainless Steel Sandwich Panels with a Metal Foam Care for Lightweight Fan Blade Design

    NASA Technical Reports Server (NTRS)

    Min, James B.; Ghosn, Louis J.; Lerch, Bradley A.; Raj, Sai V.; Holland, Frederic A., Jr.; Hebsur, Mohan G.

    2004-01-01

    The quest for cheap, low density and high performance materials in the design of aircraft and rotorcraft engine fan and propeller blades poses immense challenges to the materials and structural design engineers. Traditionally, these components have been fabricated using expensive materials such as light weight titanium alloys, polymeric composite materials and carbon-carbon composites. The present study investigates the use of P sandwich foam fan blade made up of solid face sheets and a metal foam core. The face sheets and the metal foam core material were an aerospace grade precipitation hardened 17-4 PH stainless steel with high strength and high toughness. The stiffness of the sandwich structure is increased by separating the two face sheets by a foam core. The resulting structure possesses a high stiffness while being lighter than a similar solid construction. Since the face sheets carry the applied bending loads, the sandwich architecture is a viable engineering concept. The material properties of 17-4 PH metal foam are reviewed briefly to describe the characteristics of the sandwich structure for a fan blade application. A vibration analysis for natural frequencies and P detailed stress analysis on the 17-4 PH sandwich foam blade design for different combinations of skin thickness and core volume %re presented with a comparison to a solid titanium blade.

  8. Sandwiched Rnyi divergence satisfies data processing inequality

    SciTech Connect

    Beigi, Salman [School of Mathematics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5746, Tehran (Iran, Islamic Republic of)] [School of Mathematics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5746, Tehran (Iran, Islamic Republic of)

    2013-12-15

    Sandwiched (quantum) ?-Rnyi divergence has been recently defined in the independent works of Wilde et al. [Strong converse for the classical capacity of entanglement-breaking channels, preprint http://arxiv.org/abs/arXiv:1306.1586 (2013)] and Mller-Lennert et al. [On quantum Rnyi entropies: a new definition, some properties and several conjectures, preprint http://arxiv.org/abs/arXiv:1306.3142v1 (2013)]. This new quantum divergence has already found applications in quantum information theory. Here we further investigate properties of this new quantum divergence. In particular, we show that sandwiched ?-Rnyi divergence satisfies the data processing inequality for all values of ? > 1. Moreover we prove that ?-Holevo information, a variant of Holevo information defined in terms of sandwiched ?-Rnyi divergence, is super-additive. Our results are based on Hlder's inequality, the Riesz-Thorin theorem and ideas from the theory of complex interpolation. We also employ Sion's minimax theorem.

  9. Galactosylated electrospun membranes for hepatocyte sandwich culture.

    PubMed

    Chien, Hsiu-Wen; Lai, Juin-Yih; Tsai, Wei-Bor

    2014-04-01

    In this work, we developed a galactocylated electrospun polyurethane membrane for sandwich culture of hepatocyte sandwich culture. The electrospun fibrous membranes were bio-functionalized with galactose molecules by a UV-crosslinked layer-by-layer polyelectrolyte multilayer deposition technique. The galactosylated electrospun membranes were employed as a top support membrane for the sandwich culture of HepG2/C3A cells on a collagen substrate. Our results demonstrate that HepG2/C3A cells covered by the galactosylated PU membranes form multi-cellular aggregates and lead to improved albumin secretion ability compared to the control membranes (unmodified PU or poly(ethylene imine)-modified PU). Our study reveals the potential of galactosylated electrospun membranes in the application of liver tissue engineering and the regeneration of liver-tissue substitutes. PMID:24583260

  10. Eigenmode sensitivity of damped sandwich structures

    NASA Astrophysics Data System (ADS)

    Lampoh, Komlanvi; Charpentier, Isabelle; El Mostafa, Daya

    2014-12-01

    The modeling of the linear free vibration of a sandwich structure including viscoelastic layers yields a complex nonlinear eigenvalue problem. In this paper, the sensitivity of eigensolutions is computed using a homotopy-based asymptotic numerical method, then a first-order automatic differentiation. The generality of the proposed method enables us to consider any analytical frequency-dependent viscoelastic law in the modeling and the sensitivity computation. Its application potential is demonstrated by computing the sensitivity of eigenmodes, eigenfrequencies and modal loss factors of sandwich beams and plates to various perturbations. xml:lang="fr"

  11. Heat pipes cool probe and sandwich panel

    NASA Technical Reports Server (NTRS)

    Camarda, C. J.; Couch, L. M.; Kelly, H. N.

    1981-01-01

    Two concepts integrate heat-pipe technology. Probe with heat-pipe cooled jacket is self-contained, passive, and has no moving parts, unlike conventional air and water cooled probes. It is used in hostile, high temperature environments like wind tunnels and powerplants or on high-speed research and hypersonic cruise vehicles. Heat-pipe sandwich panel combines structural efficiency of sandwich with thermal efficiency of heat-pipe. It is used to eliminate thermal gradients and stresses, minimize thermal distortions, and transfer heat from one face of panel to other.

  12. Mechanical behavior of dip-brazed aluminum sandwich panels

    E-print Network

    Hohmann, Brian P. (Brian Patrick)

    2007-01-01

    An experimental study was carried out to determine the mechanical behavior of sandwich panels containing cellular cores of varying shape. Compression and four point bend tests were performed on sandwich panels with square ...

  13. An Approach to Improve Locality Using Sandwich Types

    Microsoft Academic Search

    Daniela Genius; Martin Trapp; Wolf Zimmermann

    1998-01-01

    We show how to increase locality of object-oriented programs using several heaps. We introduce the notion of sandwich types which allow a coarser view on objects. Our idea for increasing locality is to use one heap per object of sandwich types. We demonstrate by performance measurements the effect of this strategy on running time, and show how to derive sandwich

  14. The use of Ansys to calculate sandwich Vincent Manet

    E-print Network

    Paris-Sud XI, Université de

    The use of Ansys to calculate sandwich structures Vincent Manet ´Ecole des Mines de Saint sandwich beam subjected to a uniform pressure using different modellings offered by the software Ansys 5's moduli of layers using Plane 82 elements. Key words: Ansys, sandwich structure, interface stresses, local

  15. Low velocity impact denting of HSSA lightweight sandwich panel

    Microsoft Academic Search

    D. W. Zhou; W. J. Stronge

    2006-01-01

    Slow speed impact by a small mass can cause residual denting without perforation of a fibrous core sandwich panel that has thin facesheets. Denting depends on the kinetic energy, compliance and nose shape of the colliding body as well as the compliance and mass density of the sandwich panel. Collision experiments were carried out with fibrous core sandwich panels of

  16. Impact-damaged graphite-thermoplastic trapezoidal-corrugation sandwich and semi-sandwich panels

    NASA Technical Reports Server (NTRS)

    Jegley, D.

    1993-01-01

    The results of a study of the effects of impact damage on compression-loaded trapezoidal-corrugation sandwich and semi-sandwich graphite-thermoplastic panels are presented. Sandwich panels with two identical face sheets and a trapezoidal corrugated core between them, and semi-sandwich panels with a corrugation attached to a single skin are considered in this study. Panels were designed, fabricated and tested. The panels were made using the manufacturing process of thermoforming, a less-commonly used technique for fabricating composite parts. Experimental results for unimpacted control panels and panels subjected to impact damage prior to loading are presented. Little work can be found in the literature about these configurations of thermoformed panels.

  17. STONE BAKED PIZZAS 10" GOURMET SANDWICHES

    E-print Network

    Oakley, Jeremy

    STONE BAKED PIZZAS 10" BIG PLATES GOURMET SANDWICHES ALL OUR PIZZA BASES ARE HOMEMADE AND TOPPED and kidney beans Spicy Chicken £4.00 Tender pieces of chicken breast in a spicy arrabiata sauce. Five Bean Chilli (v) £4.00 Chick peas, kidney beans, borlotti beans, cannellini beans, butter beans, peppers

  18. Fabrication and characterization of microscale sandwich beams

    E-print Network

    Kenis, Paul J. A.

    Fabrication and characterization of microscale sandwich beams Francisco Arias, Paul J.A. Kenis/metal cores were produced through fabrication methods that combined photolithography and electrodeposition evaluated in this study were far from those that minimize the weight, because of fabrication constraints

  19. Feedback Sandwiches Affect Perceptions but Not Performance

    ERIC Educational Resources Information Center

    Parkes, Jay; Abercrombie, Sara; McCarty, Teresita

    2013-01-01

    The feedback sandwich technique-make positive comments; provide critique; end with positive comments-is commonly recommended to feedback givers despite scant evidence of its efficacy. These two studies (N = 20; N = 350) of written peer feedback with third-year medical students on clinical patient note-writing assignments indicate that students

  20. Cellular Metal Truss Core Sandwich Structures**

    E-print Network

    Wadley, Haydn

    rigidity. Honeycomb core sandwich structures are the current state-of-the-art choice for weight sensitive. Introduction Cellular metals have attracted interest as alternatives to honeycomb when used as the cores (program managers, L. Christodoulou and S. Fishman). Closed cell honeycomb core structures are widely used

  1. Effects of the aromatic substitution pattern in cation-? sandwich complexes.

    PubMed

    Wireduaah, Selina; Parker, Trent M; Lewis, Michael

    2013-03-28

    A computational study investigating the effects of the aromatic substitution pattern on the structure and binding energies of cation-? sandwich complexes is reported. The correlation between the binding energies (Ebind) and Hammett substituent constants is approximately the same as what is observed for cation-? half-sandwich complexes. For cation-? sandwich complexes where both aromatics contain substituents the issue of relative conformation is a possible factor in the strength of the binding; however, the work presented here shows the Ebind values are approximately the same regardless of the relative conformation of the two substituted aromatics. Finally, recent computational work has shown conflicting results on whether cation-? sandwich Ebind values (Ebind,S) are approximately equal to twice the respective half-sandwich Ebind values (Ebind,HS), or if cation-? sandwich Ebind,S values are less than double the respective half-sandwich Ebind,HS values. The work presented here shows that for cation-? sandwich complexes involving substituted aromatics the Ebind,S values are less than twice the respective half-sandwich Ebind,HS values, and this is termed nonadditive. The extent to which the cation-? sandwich complexes investigated here are nonadditive is greater for B3LYP calculated values than for MP2 calculated values and for sandwich complexes with electron-donating substituents than those with electron-withdrawing groups. PMID:23452189

  2. Sound Transmission through a Cylindrical Sandwich Shell with Honeycomb Core

    NASA Technical Reports Server (NTRS)

    Tang, Yvette Y.; Robinson, Jay H.; Silcox, Richard J.

    1996-01-01

    Sound transmission through an infinite cylindrical sandwich shell is studied in the context of the transmission of airborne sound into aircraft interiors. The cylindrical shell is immersed in fluid media and excited by an oblique incident plane sound wave. The internal and external fluids are different and there is uniform airflow in the external fluid medium. An explicit expression of transmission loss is derived in terms of modal impedance of the fluids and the shell. The results show the effects of (a) the incident angles of the plane wave; (b) the flight conditions of Mach number and altitude of the aircraft; (c) the ratios between the core thickness and the total thickness of the shell; and (d) the structural loss factors on the transmission loss. Comparisons of the transmission loss are made among different shell constructions and different shell theories.

  3. Timing resolution of Shisk-Kebab'' lead scintillator sandwich calorimeters

    SciTech Connect

    Kistenev, E.; White, S. (Brookhaven National Lab., Upton, NY (United States)); Pischalnikov, Y.; Protopopov, Y.; Rykalin, V. (Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation))

    1992-01-01

    We have constructed lead scintillator sandwich calorimeters with 1/4 [chi][sub o] sampling frequency and total thickness [approximately]16[chi][sub o]. The 4 mm thick scintillator plates are read out by wavelength shifter fibers 1 mm in diameter which pass through holes penetrating the plates on a .95 cm [times] .95 cm grid (Shish-Kebab geometry). We tested these modules in the A2 test beam at Brookhaven using low energy electrons and hadrons. Results are here presented on electron energy and time-of-flight resolution obtained with various combinations of scintillators and wavelength shifters. We also describe results on e/[pi] separation obtained with a new technique for the longitudinal segmentation.

  4. Timing resolution of ``Shisk-Kebab`` lead scintillator sandwich calorimeters

    SciTech Connect

    Kistenev, E.; White, S. [Brookhaven National Lab., Upton, NY (United States); Pischalnikov, Y.; Protopopov, Y.; Rykalin, V. [Institut Fiziki Vysokikh Ehnergij, Protvino (Russian Federation)

    1992-12-31

    We have constructed lead scintillator sandwich calorimeters with 1/4 {chi}{sub o} sampling frequency and total thickness {approximately}16{chi}{sub o}. The 4 mm thick scintillator plates are read out by wavelength shifter fibers 1 mm in diameter which pass through holes penetrating the plates on a .95 cm {times} .95 cm grid (Shish-Kebab geometry). We tested these modules in the A2 test beam at Brookhaven using low energy electrons and hadrons. Results are here presented on electron energy and time-of-flight resolution obtained with various combinations of scintillators and wavelength shifters. We also describe results on e/{pi} separation obtained with a new technique for the longitudinal segmentation.

  5. Embedded piezoelectric ceramic transducers in sandwiched beams

    NASA Astrophysics Data System (ADS)

    Gopal Madhav Annamdas, Venu; Kiong Soh, Chee

    2006-04-01

    Surface bonded piezoelectric ceramic (PZT) transducers are currently the most prominent area of research in structural health monitoring using electromechanical impedance methods. This paper presents a new embedded PZT patch and its interaction with the host sandwiched beam. Durability and protection from surface finish, vandalism and the environment are important features of the embedment. The paper also demonstrates the use of thickness vibration of the PZT patch in electromechanical admittance formulations. This embedded PZT-structure interaction model is based on the new concept of 'average sum impedance'. The formulations used for this model can be conveniently employed to extract the mechanical impedance of any 'unknown' PZT patch embeddable plane structure. The mechanical impedance of the structure is obtained from the admittance signatures of the embedded PZT patch. The proposed model is experimentally verified on sandwiched beams.

  6. Mechanical and thermal buckling analysis of sandwich panels under different edge conditions

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    1993-01-01

    By using the Rayleigh-Ritz method of minimizing the total potential energy of a structural system, combined load (mechanical or thermal load) buckling equations are established for orthotropic rectangular sandwich panels supported under four different edge conditions. Two-dimensional buckling interaction curves and three dimensional buckling interaction surfaces are constructed for high-temperature honeycomb-core sandwich panels supported under four different edge conditions. The interaction surfaces provide easy comparison of the panel buckling strengths and the domains of symmetrical and antisymmetrical buckling associated with the different edge conditions. Thermal buckling curves of the sandwich panels also are presented. The thermal buckling conditions for the cases with and without thermal moments were found to be identical for the small deformation theory. In sandwich panels, the effect of transverse shear is quite large, and by neglecting the transverse shear effect, the buckling loads could be overpredicted considerably. Clamping of the edges could greatly increase buckling strength more in compression than in shear.

  7. Learning About Ratios: A Sandwich Study

    NSDL National Science Digital Library

    Sheryl Weinberg

    1999-01-16

    This lesson introduces students to the concept of ratio through a hands-on, delicious experiment. After an introductory activity where students identify the ratio of girls to boys in a group of 10 selected students, they create six different peanut butter and jelly sandwiches with different ingredient ratios to find which is the tastiest. Students then plan their own similar experiment using other concoctions which can be expressed in ratios.

  8. Testing Falling Peanut Butter Sandwich Myth

    NSDL National Science Digital Library

    Twin Cities Public Television, Inc.

    2006-01-01

    In this activity related to rotational inertia (page 1 of the PDF), learners will use a bit of scientific experimenting to test if open-faced peanut butter sandwiches really do always land peanut butter side down. Learners will also test other variables, such as drop height, size of bread slice, and whatever else learners can think of, to arrive at some sound conclusions. Relates to the linked video, DragonflyTV: Microgravity.

  9. EVALUATION OF THE MATERIAL PROPERTIES OF RESIN-IMPREGNATED NOMEX PAPER AS BASIS FOR THE SIMULATION OF THE IMPACT BEHAVIOUR OF HONEYCOMB SANDWICH

    Microsoft Academic Search

    Falk Hhnel; Klaus Wolf

    Driven by stringent weight saving requirements composite sandwich construction has evolved as one of the basic structural design concepts for load-carrying components of advanced aeroplanes and helicopters. Particularly, sandwich using laminated carbon fibre reinforced plastics (CFRP) as face sheets and NOMEX honeycombs as core material is increasingly used due to features such as high strength-to-weight and stiffness-to-weight ratios as well

  10. BMI Sandwich Wing Box Analysis and Test

    NASA Technical Reports Server (NTRS)

    Palm, Tod; Mahler, Mary; Shah, Chandu; Rouse, Marshall; Bush, Harold; Wu, Chauncey; Small, William J.

    2000-01-01

    A composite sandwich single bay wing box test article was developed by Northrop Grumman and tested recently at NASA Langley Research Center. The objectives for the wing box development effort were to provide a demonstration article for manufacturing scale up of structural concepts related to a high speed transport wing, and to validate the structural performance of the design. The box concept consisted of highly loaded composite sandwich wing skins, with moderately loaded composite sandwich spars. The dimensions of the box were chosen to represent a single bay of the main wing box, with a spar spacing of 30 inches, height of 20 inches constant depth, and length of 64 inches. The bismaleimide facesheet laminates and titanium honeycomb core chosen for this task are high temperature materials able to sustain a 300F service temperature. The completed test article is shown in Figure 1. The tests at NASA Langley demonstrated the structures ability to sustain axial tension and compression loads in excess of 20,000 lb/in, and to maintain integrity in the thermal environment. Test procedures, analysis failure predictions, and test results are presented.

  11. The dynamic indentation response of sandwich panels with a corrugated or Y-frame core

    E-print Network

    St-Pierre, L.; Fleck, N. A.; Deshpande, V. S.

    2014-12-30

    in the future as maritime traffic increases and as vessels become larger and faster. Thus, it is vital that ship structures have adequate strength and energy absorption capacity to resist collisions. The crashworthiness of most tankers relies on a... conventional double hull design, with minimal coupling between inner and outer hulls. However, improved crash performance can be obtained by sandwich construction [2]. Similarly, the crashworthiness of land vehicles (and their resistance to security...

  12. A comparative evaluation of crashworthy composite sandwich structures

    Microsoft Academic Search

    G. Pitarresi; J. J. Carruthers; A. M. Robinson; G. Torre; J. M. Kenny; S. Ingleton; O. Velecela; M. S. Found

    2007-01-01

    This paper describes an experimental evaluation of the energy absorption properties of a series of novel designs for cost-effective crashworthy composite sandwich structures. All the designs are based on the concept of the tied-core sandwich, i.e. the use of additional core reinforcements that act to tie the opposing facings of a sandwich together, thus preventing catastrophic failure under edgewise loading.

  13. Buckling Analysis of Debonded Sandwich Panel Under Compression

    NASA Technical Reports Server (NTRS)

    Sleight, David W.; Wang, John T.

    1995-01-01

    A sandwich panel with initial through-the-width debonds is analyzed to study the buckling of its faceskin when subject to an in-plane compressive load. The debonded faceskin is modeled as a beam on a Winkler elastic foundation in which the springs of the elastic foundation represent the sandwich foam. The Rayleigh-Ritz and finite-difference methods are used to predict the critical buckling load for various debond lengths and stiffnesses of the sandwich foam. The accuracy of the methods is assessed with a plane-strain finite-element analysis. Results indicate that the elastic foundation approach underpredicts buckling loads for sandwich panels with isotropic foam cores.

  14. Development of the LANL sandwich test.

    SciTech Connect

    Hill, L. G. (Larry G.)

    2001-01-01

    The Sandwich test is slab-variant of the ubiquitous copper cylinder test, and is used to obtain high explosive product equation-of-state information in the same manner as its predecessor. The motivation for slab geometry is (1) better high-pressure resolution, and (2) the ability to accommodate initial temperature extremes for solid explosive samples. The present design allows initial temperatures from -55 C to 75 C. The pros and cons of the two geometries we discussed, followed by a description of the mechanical design and instrumentation. gample data for several ambient PBX 9501 tests demonstrates excellent data quality and repeatability.

  15. Manufacturing and tribological properties of sandwich materials with chemically bonded PTFE-PA 66 and PA 66\\/GF

    Microsoft Academic Search

    R. Franke; I. Haase; D. Lehmann; B. Hupfer; A. Janke

    2007-01-01

    The sandwich molding process for the production of multi-component shaped parts is gaining increasing importance. With this procedure different materials, such as functional and construction materials, can be combined to form composite construction parts with good load-bearing characteristics.The investigations were performed with a pure PA 66 and 4 different modified PTFE-PA 66 compounds with a PA 66 injection type matrix.

  16. Experimental investigation and constitutive modeling of metallic honeycombs in sandwich structures

    E-print Network

    Mohr, Dirk, 1976-

    2003-01-01

    Traditionally, honeycomb sandwich structures are designed in the elastic range, but recent studies on the crushing of sandwich profiles have shown their potential in crashworthiness applications. Thin sandwich sheets also ...

  17. Modeling of Sandwich Sheets with Metallic Foam

    NASA Astrophysics Data System (ADS)

    Mata, H.; Jorge, R. Natal; Santos, A.; Fernandes, A. A.; Valente, R. A. F.; Parente, M. P. L.

    2011-08-01

    World-wide vehicles safety experts agree that significant further reductions in fatalities and injuries can be achieved as a result of the use of new lightweight and energy absorbing materials. On this work, the authors present the development and evaluation of an innovative system able to perform reliable panels of sandwich sheets with metallic foam cores for industrial applications. The mathematical model used to describe the behavior of sandwich shells with metal cores foam is presented and some numerical examples are presented. In order to validate those results mechanical experiments are carried out. Using the crushable foam constitutive model, available on ABAQUS, a set of different mechanical tests were simulated. There are two variants of this model available on ABAQUS: the volumetric hardening model and the isotropic hardening model. As a first approximation we chose the isotropic hardening variant. The isotropic hardening model available uses a yield surface that is an ellipse centered at the origin in the p-q stress plane. Based on this constitutive model for the foam, numerical simulations of the tensile and bulge test will be conducted. The numerical results will be validated using the data obtained from the experimental results.

  18. Finite Element Modeling of the Buckling Response of Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Rose, Cheryl A.; Moore, David F.; Knight, Norman F., Jr.; Rankin, Charles C.

    2002-01-01

    A comparative study of different modeling approaches for predicting sandwich panel buckling response is described. The study considers sandwich panels with anisotropic face sheets and a very thick core. Results from conventional analytical solutions for sandwich panel overall buckling and face-sheet-wrinkling type modes are compared with solutions obtained using different finite element modeling approaches. Finite element solutions are obtained using layered shell element models, with and without transverse shear flexibility, layered shell/solid element models, with shell elements for the face sheets and solid elements for the core, and sandwich models using a recently developed specialty sandwich element. Convergence characteristics of the shell/solid and sandwich element modeling approaches with respect to in-plane and through-the-thickness discretization, are demonstrated. Results of the study indicate that the specialty sandwich element provides an accurate and effective modeling approach for predicting both overall and localized sandwich panel buckling response. Furthermore, results indicate that anisotropy of the face sheets, along with the ratio of principle elastic moduli, affect the buckling response and these effects may not be represented accurately by analytical solutions. Modeling recommendations are also provided.

  19. Active Vibration Suppression of Sandwich Beams using Piezoelectric Shear Actuators

    E-print Network

    Vel, Senthil

    Active Vibration Suppression of Sandwich Beams using Piezoelectric Shear Actuators Senthil S. Vel1 of the piezoelectric actuators to cause transverse shear deformation of the sandwich beam. Active vibration suppression actuators. An exact analysis of the free vibration, forced vibration and active vibration suppression

  20. High Velocity Impact Response of Composite Lattice Core Sandwich Structures

    NASA Astrophysics Data System (ADS)

    Wang, Bing; Zhang, Guoqi; Wang, Shixun; Ma, Li; Wu, Linzhi

    2014-04-01

    In this research, carbon fiber reinforced polymer (CFRP) composite sandwich structures with pyramidal lattice core subjected to high velocity impact ranging from 180 to 2,000 m/s have been investigated by experimental and numerical methods. Experiments using a two-stage light gas gun are conducted to investigate the impact process and to validate the finite element (FE) model. The energy absorption efficiency (EAE) in carbon fiber composite sandwich panels is compared with that of 304 stainless-steel and aluminum alloy lattice core sandwich structures. In a specific impact energy range, energy absorption efficiency in carbon fiber composite sandwich panels is higher than that of 304 stainless-steel sandwich panels and aluminum alloy sandwich panels owing to the big density of metal materials. Therefore, in addition to the multi-functional applications, carbon fiber composite sandwich panels have a potential advantage to substitute the metal sandwich panels as high velocity impact resistance structures under a specific impact energy range.

  1. Practical Instruction in Tissue Culture and Cytogenetics for Sandwich Students.

    ERIC Educational Resources Information Center

    Williams, D. C.; Bishun, N. P.

    1973-01-01

    Describes the training and practical techniques taught to students involved in a sandwich course at the Tissue Culture and Cytogenetics Unit of the Marie Curie Memorial Foundation, Surrey, England. Students spend a minimum of six months involved in the sandwich course before returning to university for a final academic year. (JR)

  2. Ruthenium Half-Sandwich Complexes as Protein Kinase Inhibitors: An

    E-print Network

    Meggers, Eric

    Ruthenium Half-Sandwich Complexes as Protein Kinase Inhibitors: An N-Succinimidyl Ester for Rapid@sas.upenn.edu Received August 22, 2006 ABSTRACT Cyclopentadienyl half-sandwich ruthenium complexes have been demonstrated-chelating pyridocarbazole ligand, whereas the carbohydrate is replaced by a ruthenium fragment. The crystal structures

  3. Indentation study of foam core sandwich composite panels

    Microsoft Academic Search

    V. Rizov; A. Shipsha; D. Zenkert

    2005-01-01

    Due to their high stiffness and strength to weight ratios, composite sandwich structures have proven their usefulness in a large number of applications in various technical fields, especially in aeronautics, automotive and civil engineering. One of the main drawbacks of sandwich structures is the loss of load caring capacity due to indentation damages. The purpose of the present work is

  4. A Cost Basis for Resource Allocation for Sandwich Courses.

    ERIC Educational Resources Information Center

    Taylor, Bryan J. R.

    1984-01-01

    The use of a computer-based resource allocation procedure for cooperative education ("sandwich" coursework) at the University of Bath in Great Britain is discussed. Costs of undergraduate sandwich courses are compared with those of the more traditional 3-year, full-time undergraduate courses in British universities. Distinction is made between

  5. Structural performance of metallic sandwich beams with hollow truss cores

    E-print Network

    Wadley, Haydn

    the core [13,14]. Any open cell metallic structure that allows coolant flow can be used as a heat exchange strong lightweight designs and to enable performance comparisons with other sandwich structures. ? 2006; Lightweight structures; Hollow tube core 1. Introduction Metallic sandwich panels with various honeycomb, lat

  6. Dynamic Stability of a Sandwich Beam with Magnetorheological Core

    Microsoft Academic Search

    Zi-Fong Yeh; Yan-Shin Shih

    2006-01-01

    This study investigated the dynamic stability of a simply supported sandwich beam with a magnetorheological core under an axial harmonic and parametric load. The complex modulus of the magnetorheological material is a function of the applied magnetic field. The governing equation of motion is theoretically derived using the Mead and Markus sandwich beam model, and also by applying Galerkin's method

  7. Influence of reinforcement type on the mechanical behavior and fire response of hybrid composites and sandwich structures

    NASA Astrophysics Data System (ADS)

    Giancaspro, James William

    Lightweight composites and structural sandwich panels are commonly used in marine and aerospace applications. Using carbon, glass, and a host of other high strength fiber types, a broad range of laminate composites and sandwich panels can be developed. Hybrid composites can be constructed by laminating multiple layers of varying fiber types while sandwich panels are manufactured by laminating rigid fiber facings onto a lightweight core. However, the lack of fire resistance of the polymers used for the fabrication remains a very important problem. The research presented in this dissertation deals with an inorganic matrix (Geopolymer) that can be used to manufacture laminate composites and sandwich panels that are resistant up to 1000C. This dissertation deals with the influence of fiber type on the mechanical behavior and the fire response of hybrid composites and sandwich structures manufactured using this resin. The results are categorized into the following distinct studies. (i) High strength carbon fibers were combined with low cost E-glass fibers to obtain hybrid laminate composites that are both economical and strong. The E-glass fabrics were used as a core while the carbon fibers were placed on the tension face and on both tension and compression faces. (ii) Structural sandwich beams were developed by laminating various types of reinforcement onto the tension and compression faces of balsa wood cores. The flexural behavior of the beams was then analyzed and compared to beams reinforced with organic composite. The effect of core density was evaluated using oak beams reinforced with inorganic composite. (iii) To measure the fire response, balsa wood sandwich panels were manufactured using a thin layer of a fire-resistant paste to serve for fire protection. Seventeen sandwich panels were fabricated and tested to measure the heat release rates and smoke-generating characteristics. The results indicate that Geopolymer can be effectively used to fabricate both high strength composite plates and sandwich panels. A 2 mm thick coating of fireproofing on balsa wood is sufficient to satisfy FAA fire requirements.

  8. Development, testing, and numerical modeling of a foam sandwich biocomposite

    NASA Astrophysics Data System (ADS)

    Chachra, Ricky

    This study develops a novel sandwich composite material using plant based materials for potential use in nonstructural building applications. The face sheets comprise woven hemp fabric and a sap based epoxy, while the core comprises castor oil based foam with waste rice hulls as reinforcement. Mechanical properties of the individual materials are tested in uniaxial compression and tension for the foam and hemp, respectively. The sandwich composite is tested in 3 point bending. Flexural results are compared to a finite element model developed in the commercial software Abaqus, and the validated model is then used to investigate alternate sandwich geometries. Sandwich model responses are compared to existing standards for nonstructural building panels, showing that the novel material is roughly half the strength of equally thick drywall. When space limitations are not an issue, a double thickness sandwich biocomposite is found to be a structurally acceptable replacement for standard gypsum drywall.

  9. Tethered-bead, immune sandwich assay.

    PubMed

    Silver, Jonathan; Li, Zhenyu; Neuman, Keir

    2015-01-15

    We describe a proof-of-principle, immune sandwich assay in which immune complexes link micron-size beads via DNA tethers to a sensor surface. The number of tethered beads, counted using low-magnification microscopy, provides a measure of the concentration of analyte. The prototype assay was sensitive to pM concentration of analyte. In theory, the assay could be sensitive to sub-fM analyte because beads attached via single-immune complexes and DNA strands form tethers, and tether formation in the absence of analyte is extremely rare. The limiting step at present is binding of streptavidin at the end of DNA to biotin on capture beads. Potential advantages of this type of sensor are discussed. PMID:25064819

  10. Peanut Butter Cracker Sandwich Manufacturing Module

    NSDL National Science Digital Library

    For many engineers, their first position after obtaining a B.S. degree is in manufacturing. Job titles like process engineer, product engineer, and quality engineer are common and are directly involved in manufacturing. Most engineering curricula do not cover manufacturing concepts. A student may not even have an opportunity through electives to study manufacturing since smaller engineering colleges rarely have a department of Manufacturing Engineering.A module on peanut butter cracker manufacturing was developed for the Introduction to Engineering course taken by most engineering students in their freshman year. The objective for the students is to design, build and then run a process to manufacture peanut butter cracker sandwiches. The culminating activity is a pilot production run where the students are assigned human operators for their process. The goal for the students is to make a profit during the pilot production run. Material costs, labor costs, quality specifications and selling price all determine whether or not the process was successful. The module includes activities where the students perform calculations and use Excel graphs to determine the process time required to make a profit, the impact of the number of operators on production, the interplay between fixed and variable costs, and the effect of yield on their profit. Students are required to write operating procedures and order supplies based on predictions of the quantity of sandwiches they will produce. Students also learn about quality control and process control, the cost of automation, development costs, and challenges in training operators. After more than two weeks of preparation, the students have 10 minutes to train their operators, and then the operators run the process for 10 minutes. After production day, the students write a report that includes an analysis of their production performance and suggested process modifications. Overall, the module provides a fun and informative introduction to some fundamental manufacturing concepts.The module learning objectives, section descriptions and handouts are included.

  11. Transmission Loss and Absorption of Corrugated Core Sandwich Panels With Embedded Resonators

    NASA Technical Reports Server (NTRS)

    Allen, Albert R.; Schiller, Noah H.; Zalewski, Bart F.; Rosenthal, Bruce N.

    2014-01-01

    The effect of embedded resonators on the diffuse field sound transmission loss and absorption of composite corrugated core sandwich panels has been evaluated experimentally. Two 1.219 m 2.438 m panels with embedded resonator arrangements targeting frequencies near 100 Hz were evaluated using non-standard processing of ASTM E90-09 acoustic transmission loss and ASTM C423-09a room absorption test measurements. Each panel is comprised of two composite face sheets sandwiching a corrugated core with a trapezoidal cross section. When inlet openings are introduced in one face sheet, the chambers within the core can be used as embedded acoustic resonators. Changes to the inlet and chamber partition locations allow this type of structure to be tuned for targeted spectrum passive noise control. Because the core chambers are aligned with the plane of the panel, the resonators can be tuned for low frequencies without compromising the sandwich panel construction, which is typically sized to meet static load requirements. Absorption and transmission loss performance improvements attributed to opening the inlets were apparent for some configurations and inconclusive for others.

  12. Calibration of an analytical thermal model for an epoxy-based composite sandwich design

    NASA Astrophysics Data System (ADS)

    Reinarts, Thomas R.; Davis, Darrell; Stuckey, Charles I.

    2001-02-01

    An epoxy-based sandwich configuration was designed to meet the structural and thermal requirements of a nose cap for the space shuttle solid rocket boosters (SRB's). This project was suspended in late 1999, but the information gathered during this work is unique in the sense that portions of graphite-epoxy layers were modeled at temperatures exceeding their glass transition temperatures. This work presents the results of the thermal model calibration efforts. A symmetric sandwich configuration was chosen that includes an inner and outer structural skin with a graphite-epoxy composite, Hexcel's AGP370-8H/3501-6 (AS4/3501-6), and a center epoxy-based syntactic core. 3M SC350G, that provides thermal protection. Each graphite-epoxy section consists of seven layers, each layer with a 0, 90, or +/-45 graphite fiber orientation. Three flat panels (0.3050.483 m top view dimensions) using this sandwich construction were fabricated and exposed to an aerothermal environment in the Marshall Space Flight Center (MSFC) Improved Hot Gas Facility (IHGF). Each of these panels had ten interstitial thermocouples in the panel. The exact locations of the thermocouples and thickness of the different layers were determined by X-ray evaluation. A 1-D model was generated that used the outer surface IR measured temperature as a boundary condition, and the predicted temperatures were compared with the measured temperatures, calibrating the code. .

  13. Effects of angiogenic factors and 3D-microenvironments on vascularization within sandwich cultures.

    PubMed

    Nishiguchi, Akihiro; Matsusaki, Michiya; Asano, Yoshiya; Shimoda, Hiroshi; Akashi, Mitsuru

    2014-06-01

    The invitro fabrication of vascularized tissue is a key challenge in tissue engineering, but little is known about the mechanisms of blood-capillary formation. Here we investigated the mechanisms of invitro vascularization using precisely-controlled 3D-microenvironments constructed by a sandwich culture using the cell-accumulation technique. 3D-microenvironments controlled at the single layer level showed that sandwich culture between more than 3 fibroblast-layers induced tubule formation. Moreover, the secretion of angiogenic factors increased upon increasing the number of sandwiching layers, which induced highly dense tubular networks. We found that not only angiogenic factors, but also the 3D-microenvironments of the endothelial cells, especially apical side, played crucial roles in tubule formation invitro. Based on this knowledge, the introduction of blood and lymph capillaries into mesenchymal stem cell (MSC) tissues was accomplished. These findings would be useful for the invitro vascularization of various types of engineered organs and studies on angiogenesis. PMID:24655783

  14. Optimization of Sandwich Composites Fuselages Under Flight Loads

    NASA Astrophysics Data System (ADS)

    Yuan, Chongxin; Bergsma, Otto; Koussios, Sotiris; Zu, Lei; Beukers, Adriaan

    2012-02-01

    The sandwich composites fuselages appear to be a promising choice for the future aircrafts because of their structural efficiency and functional integration advantages. However, the design of sandwich composites is more complex than other structures because of many involved variables. In this paper, the fuselage is designed as a sandwich composites cylinder, and its structural optimization using the finite element method (FEM) is outlined to obtain the minimum weight. The constraints include structural stability and the composites failure criteria. In order to get a verification baseline for the FEM analysis, the stability of sandwich structures is studied and the optimal design is performed based on the analytical formulae. Then, the predicted buckling loads and the optimization results obtained from a FEM model are compared with that from the analytical formulas, and a good agreement is achieved. A detailed parametric optimal design for the sandwich composites cylinder is conducted. The optimization method used here includes two steps: the minimization of the layer thickness followed by tailoring of the fiber orientation. The factors comprise layer number, fiber orientation, core thickness, frame dimension and spacing. Results show that the two-step optimization is an effective method for the sandwich composites and the foam sandwich cylinder with core thickness of 5 mm and frame pitch of 0.5 m exhibits the minimum weight.

  15. Development and Mechanical Behavior of FML/Aluminium Foam Sandwiches

    NASA Astrophysics Data System (ADS)

    Ba?trk, S. B.; Tano?lu, M.

    2013-10-01

    In this study, the Fiber-Metal Laminates (FMLs) containing glass fiber reinforced polypropylene (GFPP) and aluminum (Al) sheet were consolidated with Al foam cores for preparing the sandwich panels. The aim of this article is the comparison of the flexural properties of FML/Al foam sandwich panels bonded with various surface modification approaches (silane treatment and combination of silane treatment with polypropylene (PP) based film addition). The FML/foam sandwich systems were fabricated by laminating the components in a mould at 200 C under 1.5 MPa pressure. The energy absorbtion capacities and flexural mechanical properties of the prepared sandwich systems were evaluated by mechanical tests. Experiments were performed on samples of varying foam thicknesses (8, 20 and 30 mm). The bonding among the sandwich components were achieved by various surface modification techniques. The Al sheet/Al foam sandwiches were also consolidated by bonding the components with an epoxy adhesive to reveal the effect of GFPP on the flexural performance of the sandwich structures.

  16. Evaluation of Analysis Techniques for Fluted-Core Sandwich Cylinders

    NASA Technical Reports Server (NTRS)

    Lovejoy, Andrew E.; Schultz, Marc R.

    2012-01-01

    Buckling-critical launch-vehicle structures require structural concepts that have high bending stiffness and low mass. Fluted-core, also known as truss-core, sandwich construction is one such concept. In an effort to identify an analysis method appropriate for the preliminary design of fluted-core cylinders, the current paper presents and compares results from several analysis techniques applied to a specific composite fluted-core test article. The analysis techniques are evaluated in terms of their ease of use and for their appropriateness at certain stages throughout a design analysis cycle (DAC). Current analysis techniques that provide accurate determination of the global buckling load are not readily applicable early in the DAC, such as during preliminary design, because they are too costly to run. An analytical approach that neglects transverse-shear deformation is easily applied during preliminary design, but the lack of transverse-shear deformation results in global buckling load predictions that are significantly higher than those from more detailed analysis methods. The current state of the art is either too complex to be applied for preliminary design, or is incapable of the accuracy required to determine global buckling loads for fluted-core cylinders. Therefore, it is necessary to develop an analytical method for calculating global buckling loads of fluted-core cylinders that includes transverse-shear deformations, and that can be easily incorporated in preliminary design.

  17. The Bending Strength, Internal Bonding and Thickness Swelling of a Five Layer Sandwiched Bamboo Particleboard

    NASA Astrophysics Data System (ADS)

    Jamaludin, M. A.; Bahari, S. A.; Nordin, K.; Soh, T. F. T.

    2010-03-01

    The demand for wood based material is increasing but the supply is decreasing. Therefore the price of these raw materials has increased. Bamboo provides an economically feasible alternative raw material for the wood based industry. Its properties are comparable to wood. It is also compatible with the existing processing technology. Bamboo is in abundance, easy to propagate and of short maturation period. Bamboo provides a cheaper alternative resource for the wood based industry. The development of new structural components from bamboo will widen its area of application from handicrafts to furniture and building components. In this study, five layer sandwiched bamboo particleboard were manufactured. The sandwiched Bamboo PB consists of a bamboo PB core, oil palm middle veneers and thin meranti surface veneers. The physical and mechanical properties of the bamboo sandwiched particleboards were tested in accordance to the BS-EN 317:1993 [1] and BS-EN 310:1993 [2], respectively. All the samples passed the standards. The modulus of elasticity was about 352% higher than the value specified in the BS standard, BS-EN 312-4:1996 [3]. The Internal bonding was about 23% higher than the general requirements specified in the standard. On the other hand, the thickness swelling was about 6% lower than the standard. No glue line failure was observed in the strength tests. Critical failures in the IB tests were observed in the particleboards. Tension failures were observed in the surface veneers in the bending tests. The five layer sandwiched bamboo particleboard can be used for light weight construction such as furniture, and wall and door panels in buildings.

  18. Thermal behavior of a titanium honeycomb-core sandwich panel

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Jackson, Raymond H.

    1991-01-01

    Finite element thermal stress analysis was performed on a rectangular titanium honecomb-core sandwich panel which is subjected to thermal load with a temperature gradient across its depth. The distributions of normal stresses in the face sheets and the face-sheet/sandwich-core interfacial shear stresses are presented. The thermal buckling of the heated face sheet was analyzed by assuming the face sheet to be resting on an elastic foundation representing the sandwich core. Thermal buckling curves and thermal buckling load surface are presented for setting the limit for temperature gradient across the panel depth.

  19. Conjoined Cochlear Models:. the Twamp and the Sandwich

    NASA Astrophysics Data System (ADS)

    Hubbard, Allyn

    2009-02-01

    A new model of the cochlea is created by joining parts of the traveling-wave amplifier (TWAMP) and the Sandwich models. The lossy, untuned traveling-wave line of the TWAMP is retained, but the TWAMP's tuned traveling-wave line is replaced by the Sandwich's traveling-wave line that represents the reticular lamina (RL) and scala tympani. The model combines stereocilliary forces, which act between the tectorial membrane (TM) and RL, with somatic outer hair cell forces that power the Sandwich.

  20. The behavior of bonded doubler splices for composite sandwich panels

    NASA Technical Reports Server (NTRS)

    Zeller, T. A.; Weisahaar, T. A.

    1980-01-01

    The results of an investigation into the behavior of adhesively bonded doubler splices of two composite material sandwich panels are presented. The splices are studied from three approaches: analytical; numerical (finite elements); and experimental. Several parameters that characterize the splice are developed to determine their influence upon joint strength. These parameters are: doubler overlap length; core stiffness; laminate bending stiffness; the size of the gap between the spliced sandwich panels; and room and elevated temperatures. Similarities and contrasts between these splices and the physically similar single and double lap joints are discussed. The results of this investigation suggest several possible approaches to improving the strength of the sandwich splices.

  1. Compressive and shear buckling analysis of metal matrix composite sandwich panels under different thermal environments

    Microsoft Academic Search

    W. L. Ko; R. H. Jackson

    1993-01-01

    Combined inplane compressive and shear buckling analysis was conducted on flat rectangular sandwich panels using the Raleigh-Ritz minimum energy method with a consideration of transverse shear effect of the sandwich core. The sandwich panels were fabricated with titanium honeycomb core and laminated metal matrix composite face sheets. The results show that slightly slender (along unidirectional compressive loading axis) rectangular sandwich

  2. Efficient Constructions for Oneway Hash YihChun Hu Markus Jakobsson Adrian Perrig

    E-print Network

    construction, the Sandwich­chain, provides a smaller bandwidth overhead for one­way chain values, and enables efficient verification of one­way chain values if the trusted one­way chain value is far away. Our second the Sandwich­chain); and resistance against DoS attacks on authentication values. Moreover, we describe fractal

  3. Measuring Moisture Levels in Graphite Epoxy Composite Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Nurge, Mark; Youngquist, Robert; Starr, Stanley

    2011-01-01

    Graphite epoxy composite (GEC) materials are used in the construction of rocket fairings, nose cones, interstage adapters, and heat shields due to their high strength and light weight. However, they absorb moisture depending on the environmental conditions they are exposed to prior to launch. Too much moisture absorption can become a problem when temperature and pressure changes experienced during launch cause the water to vaporize. The rapid state change of the water can result in structural failure of the material. In addition, heat and moisture combine to weaken GEC structures. Diffusion models that predict the total accumulated moisture content based on the environmental conditions are one accepted method of determining if the material strength has been reduced to an unacceptable level. However, there currently doesn t exist any field measurement technique to estimate the actual moisture content of a composite structure. A multi-layer diffusion model was constructed with Mathematica to predict moisture absorption and desorption from the GEC sandwich structure. This model is used in conjunction with relative humidity/temperature sensors both on the inside and outside of the material to determine the moisture levels in the structure. Because the core materials have much higher diffusivity than the face sheets, a single relative humidity measurement will accurately reflect the moisture levels in the core. When combined with an external relative humidity measurement, the model can be used to determine the moisture levels in the face sheets. Since diffusion is temperaturedependent, the temperature measurements are used to determine the diffusivity of the face sheets for the model computations.

  4. Multifunctional composite sandwich structures utilizing embedded microvascular networks

    NASA Astrophysics Data System (ADS)

    Tye, Jordan

    Sandwich composites possess exceptional specific flexural strengths, but currently lack the capability for multifunctional use of the volumes encapsulated within their cores. The objectives of this research are to (1) fabricate sacrificial fiber with increased production rates and decreased degradation times, (2) integrate sacrificial fibers into sandwich composite skins, and (3) transport, store, and recover fluid from cells within a honeycomb composite core. Melt-mixing and extrusion of PLA and tin (II) oxalate catalyst is used to increase production rates by five orders of magnitude and reduce evacuation times by a factor of four, while substantially lowering costs and eliminating hazardous chemical waste. Sacrificial fibers are woven into and fully evacuated from sandwich composite structures. Finally, fluid is successfully transported via the patterned microvascular pathways and stored within the core compartments, enabling sandwich composites suitable for applications such as structural fluid storage, heat dissipation, and damage sensing.

  5. Modelling of crack deflection at core junctions in sandwich structures

    NASA Astrophysics Data System (ADS)

    Jakobsen, J.; Andreasen, J. H.; Thomsen, O. T.

    2009-08-01

    The paper treats the problem of crack propagation in sandwich panels with interior core junctions. When a face-core interface crack approaches a trimaterial wedge, as it may occur at a sandwich core junction, two options exist for further crack advance; one is for the interface crack to penetrate the wedge along the face-core interface, and the second is deflection along the core junction interface. Crack deflection is highly relevant and a requirement for the functionality of a newly developed peel stopper for sandwich structures. The physical model presented in this paper enables the quantitative prediction of the ratio of the toughnesses of the two wedge interfaces required to control the crack propagation, and the derived results can be applied directly in future designs of sandwich structures. The solution strategy is based on finite element analysis (FEA), and a realistic engineering practice example of a tri-material composition corresponding to face and core materials is presented.

  6. Modified Mode-I Cracked Sandwich Beam (CSB) Fracture Test

    NASA Technical Reports Server (NTRS)

    Smith, S. A.; Shivakumar, K. N.

    2001-01-01

    Five composite sandwich panels were fabricated using vacuum assisted resin transfer molding (VARTM). Four of these panels had E-glass/vinylester facesheets and one had carbon/epoxy facesheets. The sandwich panels had different density PVC foam cores. The four E-glass panels had core densities of 80, 100, 130, 200 kg/cu m. The sandwich with carbon/epoxy 3 facesheets had a core with density of 100 kg/cu m. Fracture tests were conducted using a modified Cracked Sandwich Beam (CSB) test configuration. Load displacement curves were obtained for loading and unloading of the specimens during crack growth. Various increments of crack growth were monitored. Critical Strain Energy Release Rates (SERR) were determined from the tests using the area method. The critical values of SERR can be considered the fracture toughness of the sandwich material. The fracture toughness ranged 367 J/sq m to 1350 J/sq m over the range of core densities. These results are compared to the Mode-I fracture toughness of the PVC foam core materials and values obtained for foam-cored sandwiches using the TSD specimen. Finite-element analyses (FEA) were performed for the test configuration and Strain Energy Release Rates were calculated using the Virtual Crack Closure Technique (VCCT). The SERR values determined from the FEA were scaled to the fracture loads, or critical loads, obtained from the modified CSB tests. These critical loads were in close agreement with the test values.

  7. The sandwich model: the 'music and dance' of therapeutic action.

    PubMed

    Harrison, Alexandra M

    2014-04-01

    My premise is that a 'layered' approach is necessary to understand the process of exchanges that result in therapeutic change. I imagine these processes occurring in three layers - although the number of domains in which change is taking place is actually infinite - such as in a sandwich. The top layer, or top slice of bread of the sandwich, represents a broad view of the change process; it is non-linear and includes the feature of uncertainty, a general principle of dynamic systems theory. The middle layer, or the meat of the sandwich, is explained by theories that are immediately and clinically useful to a therapist, such as psychoanalytic theories. These are primarily linear theories and use language and symbols to 'tell a story of what happened'. The bottom layer, or bottom slice of bread of the sandwich, is the micro-process; this layer includes the moment-to-moment patterns of coordinated rhythms that both communicate meaning and provide the essential scaffold for all higher-level change processes. The micro-process also requires a non-linear theory to make sense of its variability and emergent properties. Taking a bite out of the sandwich will include a 'polysemic bundle of communicative behaviors' (Harrison and Tronick, 2011). I will illustrate the 'sandwich model' with the clinical case of the analytic treatment of a 5year-old boy. PMID:24354856

  8. Enhanced Antibacterial Activity of Silver Nanoparticles/Halloysite Nanotubes/Graphene Nanocomposites with Sandwich-Like Structure

    NASA Astrophysics Data System (ADS)

    Yu, Liang; Zhang, Yatao; Zhang, Bing; Liu, Jindun

    2014-04-01

    A sandwich-like antibacterial reagent (Ag/HNTs/rGO) was constructed through the direct growth of silver nanoparticles on the surface graphene-based HNTs nanosheets. Herein, various nanomaterials were combined by adhesion effect of DOPA after self-polymerization. Ag/HNTs/rGO posses enhanced antibacterial ability against E. coli and S. aureus compared with individual silver nanoparticles, rGO nanosheets or their nanocomposites.

  9. Enhanced Antibacterial Activity of Silver Nanoparticles/Halloysite Nanotubes/Graphene Nanocomposites with Sandwich-Like Structure

    PubMed Central

    Yu, Liang; Zhang, Yatao; Zhang, Bing; Liu, Jindun

    2014-01-01

    A sandwich-like antibacterial reagent (Ag/HNTs/rGO) was constructed through the direct growth of silver nanoparticles on the surface graphene-based HNTs nanosheets. Herein, various nanomaterials were combined by adhesion effect of DOPA after self-polymerization. Ag/HNTs/rGO posses enhanced antibacterial ability against E. coli and S. aureus compared with individual silver nanoparticles, rGO nanosheets or their nanocomposites. PMID:24722502

  10. Ionic liquids of cationic sandwich complexes.

    PubMed

    Inagaki, Takashi; Mochida, Tomoyuki; Takahashi, Masashi; Kanadani, Chikahide; Saito, Toshiaki; Kuwahara, Daisuke

    2012-05-29

    Simple cationic sandwich complexes that contained alkyl- or halogen substituents provided ionic liquids (ILs) with the bis(perfluoroalkanesulfonyl)imide anion. Ferrocenium- and cobaltocenium ILs [M(C(5)H(4)R(1))(C(5)H(4)R(2))][Tf(2)N] (M=Fe, Co) and arene-ferrocenium ILs [Fe(C(5)H(4)R(1))(C(6)H(5)R(2))][Tf(2)N] were prepared and their physical properties were investigated. A detailed comparison of their thermal properties revealed the effects of molecular symmetry and substituents on their melting points. Their viscosity increased on increasing the length of the substituent on the cation and the perfluoroalkyl chain length on the anion. Upon cooling, ILs with low viscosities exhibited crystallization, whereas those with higher viscosities tended to exhibit glass transitions. Most of these salts showed phase transitions in the solid state. A magnetic-switching phenomenon was observed for the paramagnetic ferrocenium IL, which was associated with a liquid/solid transformation, based on the magnetic anisotropy of the ferrocenium cation. (57)Fe Mssbauer spectroscopy was applied to [Fe(C(5)H(4)nBu)(2)][Tf(2)N] to investigate the vibrational behavior of the iron atom in the crystal and glassy states of the ferrocenium IL. PMID:22517602

  11. Gold nanoparticles based sandwich electrochemical immunosensor.

    PubMed

    Ahirwal, Gautham Kumar; Mitra, Chanchal K

    2010-05-15

    In this report we have used gold nanoparticles (AuNPs) to covalently attach an antibody (Ab(1)) using a spacer arm. The AuNPs/Ab(1) modified gold electrode was used for a sandwich electrochemical immunoassay. The detection was done using cyclic voltammetry and impedance measurements using Horse Radish Peroxidase (HRP) as enzyme label on secondary antibody (Ab(2)) and 3,3', 5,5'-tertramethyl benzidine (TMB) as an electroactive dye. The cyclic voltammetric experiments showed three clear peaks at potentials 154 mV, -33 mV and -156 mV. There was an increase in the both anodic and cathodic current values for the peak at potential -33 mV, when H2O2 was added and the other peaks observed at potential 154 mV and -156 mV resulted due to the oxidation and reduction of TMB. The detection limit of this electrode was 2 ng/mL or 10 pg/5 microL of the analyte. The electrochemical impedance spectroscopy studies demonstrate that the formation of antigen-antibody complexes increases the series resistance and thus confirms the assembly on the electrode. This study showed that AuNPs was efficient in preserving the activity and orientation of the antibody and it can form a major platform in many clinical immunoassays. PMID:20171869

  12. Sandwich module testing for space solar power

    NASA Astrophysics Data System (ADS)

    Jaffe, Paul

    Solar power satellites have been envisioned as a means to provide electricity for terrestrial use. The approach entails collection of solar energy in space and its wireless transmission to the earth. This potentially gives the benefit of provision of baseload power while avoiding the losses due to the day/night cycle and tropospheric effects that are associated with terrestrial solar power. Proponents have contended that the implementation of such systems could offer energy security, environmental, and technological advantages to those who would undertake their development. Among recent implementations commonly proposed for SSP, the Modular Symmetrical Concentrator and other modular concepts have received considerable attention. Each employs an array of modules for performing conversion of concentrated sunlight into microwaves or laser beams for transmission to earth. The research described herein details efforts in the development and testing of photovoltaic arrays, power electronics, microwave conversion electronics, and antennas for 2.45 GHz microwave-based sandwich module prototypes. Prototypes were designed, fabricated, and subjected to the challenging conditions inherent in the space environment, including the solar concentration levels in which an array of modules might be required to operate.

  13. A study of structurally efficient graphite-thermoplastic trapezoidal-corrugation sandwich and semi-sandwich panels

    NASA Technical Reports Server (NTRS)

    Jegley, Dawn C.

    1993-01-01

    The structural efficiency of compression-loaded trapezoidal-corrugation sandwich and semi-sandwich composite panels is studied to determine their weight savings potential. Sandwich panels with two identical face sheets and a trapezoidal corrugated core between them, and semi-sandwich panels with a corrugation attached to a single skin are considered. An optimization code is used to find the minimum weight designs for critical compressive load levels ranging from 3,000 to 24,000 lb/in. Graphite-thermoplastic panels based on the optimal minimum weight designs were fabricated and tested. A finite-element analysis of several test specimens was also conducted. The results of the optimization study, the finite-element analysis, and the experiments are presented.

  14. Impact damage analysis of balsawood sandwich composite materials

    NASA Astrophysics Data System (ADS)

    Abdalslam, Suof Omran

    In this study, a new composite sandwich structure with a balsa wood core (end grain and regular balsa) in conjunction with E-glass/epoxy face sheets was proposed, fabricated, impact tested, and modeled. The behavior of the sandwich structure under low velocity impact and compression after impact was investigated. Low velocity impact tests were carried out by drop-weight impact tower at different energy levels (8J-35J) to evaluate the impact response of the sandwich structure. Visual inspection, destructive and non destructive evaluation methods have been conducted. For the sandwich plate with end grain core, the damage was very clear and can be visually detected. However, the damage in regular balsa core was not clearly visible and destructive evaluation method was used. Compression testing was done after subjecting the specimens to impact testing. Impact test results; load-time, load-deflection history and energy absorption for sandwich composites with two different cores, end grain and regular balsa were compared and they were investigated at three different impact energies. The results show that the sandwich structures with end grain core are able to withstand impact loading better than the regular balsa core because the higher stiffness of end grain core informs of sustaining higher load and higher overall energy. The results obtained from compression after impact testing show that the strengths of sandwich composites with end grain and regular balsa cores were reduced about 40% and 52%, respectively, after impact. These results were presented in terms of stress-strain curves for both damaged and undamaged specimens. Finite element analysis was conducted on the sandwich composite structure using LS-DYNA code to simulate impact test. A 3- D finite element model was developed and appropriate material properties were given to each component. The computational model was developed to predict the response of sandwich composite under dynamic loading. The experimental and finite element results were matched better for maximum load. However progressive damage accumulation could not predicted well due to lack of sophisticated material damage models in FEA codes.

  15. Synthesis and characterization of a 1D chain-like Cu6 substituted sandwich-type phosphotungstate with pendant dinuclear Cu-azido complexes

    NASA Astrophysics Data System (ADS)

    Li, Yan-Ying; Zhao, Jun-Wei; Wei, Qi; Yang, Bai-Feng; Yang, Guo-Yu

    2014-02-01

    A novel Cu-azido complex modified hexa-CuII substituted sandwich-type phosphotungstate [Cu(en)2]{[Cu2(en)2(?-1,1-N3)2(H2O)]2[Cu6(en)2(H2O)2(B-?-PW9O34)2]}6H2O (1) (en=ethylene-diamine) has been prepared under hydrothermal conditions and structurally characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. 1 displays a beautiful 1-D chain architecture constructed from sandwich-type [Cu2(en)2(?-1,1-N3)2(H2O)]2[Cu6(en)2(H2O)2(B-?-PW9O34)2]2- units and [Cu(en)2]2+ linkers. To our knowledge, 1 represents the first hexa-CuII sandwiched phosphotungstate with supporting Cu-azido complexes.

  16. Sound Transmission through Two Concentric Cylindrical Sandwich Shells

    NASA Technical Reports Server (NTRS)

    Tang, Yvette Y.; Silcox, Richard J.; Robinson, Jay H.

    1996-01-01

    This paper solves the problem of sound transmission through a system of two infinite concentric cylindrical sandwich shells. The shells are surrounded by external and internal fluid media and there is fluid (air) in the annular space between them. An oblique plane sound wave is incident upon the surface of the outer shell. A uniform flow is moving with a constant velocity in the external fluid medium. Classical thin shell theory is applied to the inner shell and first-order shear deformation theory is applied to the outer shell. A closed form for transmission loss is derived based on modal analysis. Investigations have been made for the impedance of both shells and the transmission loss through the shells from the exterior into the interior. Results are compared for double sandwich shells and single sandwich shells. This study shows that: (1) the impedance of the inner shell is much smaller than that of the outer shell so that the transmission loss is almost the same in both the annular space and the interior cavity of the shells; (2) the two concentric sandwich shells can produce an appreciable increase of transmission loss over single sandwich shells especially in the high frequency range; and (3) design guidelines may be derived with respect to the noise reduction requirement and the pressure in the annular space at a mid-frequency range.

  17. Feasibility study of a SiC sandwich neutron spectrometer

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Lei, Jiarong; Jiang, Yong; Chen, Yu; Rong, Ru; Zou, Dehui; Fan, Xiaoqiang; Chen, Gang; Li, Li; Bai, Song

    2013-04-01

    Semiconductor sandwich neutron spectrometers are suitable for in-pile measurements of fast reactor spectra thanks to their compact and relatively simple design. We have assembled and tested a sandwich neutron spectrometer based on 4H-silicon carbide (4H-SiC) Schottky diodes. The SiC diodes detect neutrons via neutron-induced charged particles (tritons and alpha particles) produced by 6Li(n,?)3H reaction. 6LiF neutron converter layers are deposited on the front surface of Schottky diodes by magnetron sputtering. The responses of SiC diodes to charged particles were investigated with an 241Am alpha source. A sandwich neutron spectrometer was assembled with two SiC Schottky diodes selected based on the charged-particle-response experimental results. The low-energy neutron response of the sandwich spectrometer was measured in the neutron field of the Chinese Fast Burst Reactor-II (CFBR-II). Spectra of alpha particles and tritons from 6Li(n,?)3H reaction were obtained with two well-resolved peaks. The energy resolution of the sum spectrum was 8.8%. The primary experimental results confirmed the 4H-SiC sandwich neutron spectrometer's feasibility.

  18. Actively cooled plate fin sandwich structural panels for hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Smith, L. M.; Beuyukian, C. S.

    1979-01-01

    An unshielded actively cooled structural panel was designed for application to a hypersonic aircraft. The design was an all aluminum stringer-stiffened platefin sandwich structure which used a 60/40 mixture of ethylene glycol/water as the coolant. Eight small test specimens of the basic platefin sandwich concept and three fatigue specimens from critical areas of the panel design was fabricated and tested (at room temperature). A test panel representative of all features of the panel design was fabricated and tested to determine the combined thermal/mechanical performance and structural integrity of the system. The overall findings are that; (1) the stringer-stiffened platefin sandwich actively cooling concept results in a low mass design that is an excellent contender for application to a hypersonic vehicle, and (2) the fabrication processes are state of the art but new or modified facilities are required to support full scale panel fabrication.

  19. Anisotropic interface magnetoresistance in Pt/Co/Pt sandwiches.

    PubMed

    Kobs, A; Hesse, S; Kreuzpaintner, W; Winkler, G; Lott, D; Weinberger, P; Schreyer, A; Oepen, H P

    2011-05-27

    We report on an effect of reduced dimensionality on the magnetotransport in cobalt layers sandwiched by platinum. In a current in-plane geometry it is found that the resistivity depends on the magnetization orientation within the plane perpendicular to the current direction. The resistivity shows a symmetry adapted cos(2) dependence on the angle to the surface normal, with the maximum along the surface normal. The Co thickness dependence of the effect in Pt/Co/Pt sandwiches clearly points out that the mechanism behind this effect originates at the Co/Pt interfaces and is disparate to the texture induced geometrical size effect. PMID:21699340

  20. Strength enhancement of sandwich panel under impact loading

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Nasri, I.; Li, H. J.

    2008-11-01

    This paper presents a study of the strength enhancement under impact loading of metallic cellular materials as well as sandwich panels with cellular core. A testing method using 60mm diameter Nylon Hopkinson pressure bars is used to investigate the rate sensitivity of various metallic cellular materials as honeycombs, foams. Finally, an inversed perforation test on sandwich panels with an instrumented pressure bar is also presented. Such a new testing setup provides piercing force time history measurement, generally inaccessible. Testing results show a notable enhancement of piercing forces, even though the skin aluminum plates and the foam cores are nearly rate insensitive.

  1. Active Vibration Suppression of Sandwich Beams using Piezoelectric Shear Actuators: Experiments and

    E-print Network

    Vel, Senthil

    Active Vibration Suppression of Sandwich Beams using Piezoelectric Shear Actuators: Experiments assessment of the vibration suppression of smart structures using piezoelectric shear actuators. Experimental of the sandwich beam. Active vibration suppression is achieved using either positive position feedback or strain

  2. GRP SANDWICH STRUCTURES FOR 'LIQUID DESIGN' ARCHITECTURE

    Microsoft Academic Search

    M. Eekhout; R. Visser

    Technical design of roof and faade structures for architecture has accelerated in the last 3 decades with successive emphasis on free form stretched membrane structures, systemized metal space structures, sophisticated tensegrity structures, glass envelope constructions and load bearing glass structures. This type of architecture is computer-based rather than culture-based. Hence it cannot be regarded as a new style of architecture,

  3. Response and Damage Tolerance of Composite Sandwich Structures under Low Velocity Impact

    Microsoft Academic Search

    I. M. Daniel; J. L. Abot; P. M. Schubel; J.-J. Luo

    The deformation and failure response of composite sandwich beams and panels under low velocity impact was reviewed and discussed.\\u000a Sandwich facesheet materials discussed are unidirectional and woven carbon\\/epoxy, and woven glass\\/vinylester composite laminates;\\u000a sandwich core materials investigated include four types of closed cell PVC foams of various densities, and balsa wood. Sandwich\\u000a beams were tested in an instrumented drop tower

  4. Real-Time Experimental Investigation on Dynamic Failure of Sandwich Structures and Layered Materials

    Microsoft Academic Search

    L. Roy Xu; Ares J. Rosakis

    \\u000a We present a systematic experimental investigation of the generation and subsequent evolution of dynamic failure modes in\\u000a sandwich structures and layered materials subjected to out-of-plane low-speed impact. Model sandwich specimens involving a\\u000a compliant polymer core sandwiched between two metal layers and other model layered materials were designed to simulate failure\\u000a evolution mechanisms in real sandwich structures and layered materials. High-speed

  5. Gravity sag of sandwich panel assemblies as applied to precision cathode strip chamber structural design

    SciTech Connect

    Horvath, J. [Lawrence Livermore National Lab., CA (United States)

    1993-09-16

    The relationship between gravity sag of a precision cathode strip chamber and its sandwich panel structural design is explored parametrically. An algorithm for estimating the dominant component of gravity sag is defined. Graphs of normalized gravity sag as a function of gap frame width and material, sandwich core edge filler width and material, panel skin thickness, gap height, and support location are calculated using the gravity sag algorithm. The structural importance of the sandwich-to-sandwich ``gap frame`` connection is explained.

  6. A sandwich structured membrane for direct methanol fuel cells operating with neat methanol

    E-print Network

    Zhao, Tianshou

    A sandwich structured membrane for direct methanol fuel cells operating with neat methanol Q.X. Wu i g h t s " A sandwich structured membrane for DMFCs operating with neat methanol is proposed. " The membrane offers better water management for DMFCs operating with neat methanol. " The sandwich structured

  7. The response of honeycomb sandwich panels under low-velocity impact loading

    Microsoft Academic Search

    M. Meo; R. Vignjevic; G. Marengo

    2005-01-01

    This paper describes the results of an experimental investigation and a numerical simulation on the impact damage on a range of sandwich panels. The test panels are representative of the composite sandwich structure of the engine nacelle Fan Cowl Doors of a large commercial aircraft. The low-velocity impact response of the composites sandwich panels is studied at five energy levels,

  8. Response of metallic pyramidal lattice core sandwich panels to high intensity impulsive loading in air

    E-print Network

    Hutchinson, John W.

    Response of metallic pyramidal lattice core sandwich panels to high intensity impulsive loading blast Fluidestructure interaction Pyramidal core Sandwich panels a b s t r a c t Small scale explosive loading of sandwich panels with low relative density pyramidal lattice cores has been used to study

  9. A multifunctional heat pipe sandwich panel structure Douglas T. Queheillalt a,*, Gerardo Carbajal b

    E-print Network

    Wadley, Haydn

    A multifunctional heat pipe sandwich panel structure Douglas T. Queheillalt a,*, Gerardo Carbajal b by multifunctionally utilizing the core as a heat pipe sandwich panel. Its interior consists of a 6061 aluminum was used to guide the design of the heat pipe sandwich panel. We describe the results of a series

  10. Compression Response of a Sandwich Fuselage Keel Panel With and Without Damage

    NASA Technical Reports Server (NTRS)

    McGowan, David M.; Ambur, Damodar R.

    1997-01-01

    Results are presented from an experimental and analytical study of a sandwich fuselage keel panel with and without damage. The fuselage keel panel is constructed of graphite-epoxy skins bonded to a honeycomb core, and is representative of a highly loaded fuselage keel structure. The face sheets of the panel contain several terminated or dropped plies along the length of the panel. The results presented provide a better understanding of the load distribution in damaged and undamaged thick-face-sheet composite sandwich structure with dropped plies and of the failure mechanisms of such structure in the presence of low-speed impact damage and discrete-source damage. The impact-damage condition studied corresponds to barely visible impact damage (BVID), and the discrete-source damage condition studied is a notch machined through both face sheets. Results are presented from an impact-damage screening study conducted on another panel of the same design to determine the impact energy necessary to inflict BVID on the panel. Results are presented from compression tests of the panel in three conditions: undamaged; BVID in two locations; and BVID in two locations and a notch through both face sheets. Surface strains in the face sheets of the undamaged panel and the notched panel obtained experimentally are compared with finite element analysis results. The experimental and analytical results suggest that for the damage conditions studied, discrete-source damage influences the structural performance more than BVID.

  11. Damage tolerance of a composite sandwich with interleaved foam core

    NASA Technical Reports Server (NTRS)

    Ishai, Ori; Hiel, Clement

    1992-01-01

    A composite sandwich panel consisting of carbon fiber-reinforced plastic (CFRP) skins and a syntactic foam core was selected as an appropriate structural concept for the design of wind tunnel compressor blades. Interleaving of the core with tough interlayers was done to prevent core cracking and to improve damage tolerance of the sandwich. Simply supported sandwich beam specimens were subjected to low-velocity drop-weight impacts as well as high velocity ballistic impacts. The performance of the interleaved core sandwich panels was characterized by localized skin damage and minor cracking of the core. Residual compressive strength (RCS) of the skin, which was derived from flexural test, shows the expected trend of decreasing with increasing size of the damage, impact energy, and velocity. In the case of skin damage, RCS values of around 50 percent of the virgin interleaved reference were obtained at the upper impact energy range. Based on the similarity between low-velocity and ballistic-impact effects, it was concluded that impact energy is the main variable controlling damage and residual strength, where as velocity plays a minor role.

  12. Damage Tolerance of Sandwich Plates with Debonded Face Sheets

    NASA Technical Reports Server (NTRS)

    Avery, John L., III; Sankar, Bhavani V.

    1998-01-01

    Axial compression tests were performed on debonded sandwich composites made of graphite/epoxy face-sheets and aramid fiber honeycomb core. The sandwich beams were manufactured using a vacuum baccrin2 process. The face-sheet and the sandwich beam were co-cured. Delamination between one of the face sheets and the core was introduced by using a Teflon layer during the curing process. Axial compression tests were performed to determine the ultimate load carrying capacity of the debonded beams. Flatwise tension tests and Double Cantilever Beam tests were performed to determine. respectively, the strength and fracture toughness of the face-sheet/core interface. From the test results semi-empirical formulas were derived for the fracture toughness and ultimate compressive load carrying capacity in terms of the core density. core thickness. face-sheet thickness and debond length. Four different failure modes and their relation to the structural properties were identified. Linear buckling analysis was found to be inadequate in predicting the compressive load carrying capacity of the debonded sandwich composites.

  13. Methods for Assessing Honeycomb Sandwich Panel Wrinkling Failures

    NASA Technical Reports Server (NTRS)

    Zalewski, Bart F.; Dial, William B.; Bednarcyk, Brett A.

    2012-01-01

    Efficient closed-form methods for predicting the facesheet wrinkling failure mode in sandwich panels are assessed. Comparisons were made with finite element model predictions for facesheet wrinkling, and a validated closed-form method was implemented in the HyperSizer structure sizing software.

  14. Load characteristics of high power sandwich piezoelectric ultrasonic transducers.

    PubMed

    Shuyu, Lin

    2005-03-01

    Based on the equivalent circuit theory, the load characteristics of high power piezoelectric ultrasonic sandwich transducers are studied. Two types of loads are studied. One is liquid load as in ultrasonic cleaning, and the other is solid load as in ultrasonic drilling and machining. The effect of load and structure of the transducer on the resonance frequency of the transducer is analyzed. It is shown that the effect of load on the resonance frequency of sandwich transducers with different structures is different. For liquid load as in ultrasonic cleaning, the effect of the load on the resonance frequency of the sandwich transducer with symmetrical structure is the largest. It is the smallest for the transducer with its displacement node in the back metal cylinder. For solid load as in ultrasonic drilling and machining, the effect of the load on the resonance frequency of the sandwich transducer with its displacement node in the front metal cylinder is the largest. It is also the smallest for the transducer with its displacement node in the back metal cylinder. On the other hand, for some applications, such as ultrasonic drilling, when the lateral dimension of the tool is much less than that of the transducer, its effect on the resonance frequency of the transducer is small. The conclusions are useful in designing vibrating systems for different ultrasonic applications. PMID:15737387

  15. The dynamic response of composite sandwich beams to transverse impact

    E-print Network

    Fleck, Norman A.

    configuration with composite face- sheets and a core made from PVC foam or end-grain balsa wood. High is such that a low density PVC foam core outperforms a higher density PVC foam core. End-grain balsa wood has a superior stiffness and strength to that of PVC foam in compression and in shear. Consequently, sandwich

  16. Star cell type core configuration for structural sandwich materials

    DOEpatents

    Christensen, Richard M. (Danville, CA)

    1995-01-01

    A new pattern for cellular core material used in sandwich type structural materials. The new pattern involves star shaped cells intermixed with hexagonal shaped cells. The new patterned cellular core material includes star shaped cells interconnected at points thereof and having hexagonal shape cells positioned adjacent the star points. The new pattern allows more flexibility and can conform more easily to curved shapes.

  17. Damping characteristics of electro-rheological fluid sandwich beams

    E-print Network

    Phani, A. Srikantha

    to critically examine the damping mechanisms in sandwich beams filled with electro-rheological (ER) fluids. ER are controllable, resulting in the enhancement of shear stress and viscosity. In some cases the development properties of ER fluids make them attractive for use in devices such as clutches, valves, shock absorbers

  18. Magic sandwich echo relaxation mapping of anisotropic systems.

    PubMed

    Regatte, Ravinder R; Schweitzer, Mark E; Jerschow, Alexej; Reddy, Ravinder

    2007-04-01

    The main objective of this article was (i) to refocus the residual dipolar and quadrupolar interactions in anisotropic tissues employing magic sandwich echo (MSE) imaging and to compare the results with that of conventional spin-echo (SE) imaging, and (ii) to quantify MSE relaxation and dispersion characteristics in bovine Achilles tendon and compare with spin-lattice relaxation time constant in the rotating frame (T(1rho)). Magic sandwich echo weighted images are approximately 75-100% higher in signal-to-noise ratio than the corresponding T(2)-weighted images. Magic sandwich echo relaxation times varied from 13+/-2 to 19+/-3 ms (mean+/-S.D.), depending upon the structural location of tendon. T(2) relaxation times only varied from 4+/-1 to 10+/-3 ms (mean+/-S.D.) on the same corresponding locations. Magic sandwich echo provides approximately 100% enhancement in relaxation times compared to T(2). Preliminary results based on bovine Achilles tendon and cartilage specimens suggest that the MSE technique has potential for refocusing residual dipolar as well as quadrupolar interactions in anisotropic systems and yields higher intensities than conventional SE imaging as well as T(1rho)-encoded imaging, especially at low-burst pulse amplitudes (250 and 500 Hz). PMID:17371736

  19. Multifunctional thermal barrier coating in aerospace sandwich panels

    Microsoft Academic Search

    Cody H. Nguyen; K. Chandrashekhara; Victor Birman

    The paper is concerned with the effectiveness of multifunctional thermal barrier coatings employed in sandwich panels with a dual objective, i.e. slowing heat transfer from the surface exposed to thermal load and improvements in the thermomechanical response, including higher strength and stiffness. The solution is obtained for a typical aerospace panel mimicking thermal loading at a supersonic high-altitude flight. The

  20. Sound radiation from a line forced perforated elastic sandwich panel

    E-print Network

    Abrahams, I. David

    Sound radiation from a line forced perforated elastic sandwich panel I. David Abrahams Department INTRODUCTION Sound transmission through panels has long been a sub- ject of importance in a variety- plates separated by stiffeners or ribs in between.2 The trans- mission and reflection of sound waves

  1. Detection of entrapped moisture in honeycomb sandwich structures

    NASA Technical Reports Server (NTRS)

    Hallmark, W. B.

    1967-01-01

    Thermal neutron moisture detection system detects entrapped moisture in intercellular areas of bonded honeycomb sandwich structures. A radium/beryllium fast neutron source bombards a specimen. The emitted thermal neutrons from the target nucleus are detected and counted by a boron trifluoride thermal neutron detector.

  2. Load characteristics of high power sandwich piezoelectric ultrasonic transducers

    Microsoft Academic Search

    Lin Shuyu

    2005-01-01

    Based on the equivalent circuit theory, the load characteristics of high power piezoelectric ultrasonic sandwich transducers are studied. Two types of loads are studied. One is liquid load as in ultrasonic cleaning, and the other is solid load as in ultrasonic drilling and machining. The effect of load and structure of the transducer on the resonance frequency of the transducer

  3. STUDIO SULLA PROPAGAZIONE DI CRICCHE IN PANNELLI SANDWICH (AL NOMEX)

    Microsoft Academic Search

    M. Giglio; A. Manes

    Sommario In questo lavoro viene analizzato il comportamento Damage Tolerant di un pannello a costruzione sandwich in Alluminio-Nomex utilizzato per fusoliere di elicotteri e soggetto a carico di taglio. Il provino stato testato in una cornice dedicata per trasmettere un carico pulsante di puro taglio. Una cricca artificiale stata realizzata al centro del pannello su una delle pelli

  4. Vibration and acoustic properties of honeycomb sandwich structures subject to variable incident plane-wave angle pressure loads

    NASA Astrophysics Data System (ADS)

    Yan, Jiaxue

    Honeycomb structures are widely used in many areas for their material characteristics such as high strength-to-weight ratio, stiffness-to-weight, sound transmission, and other properties. Honeycomb structures are generally constructed from periodically spaced tessellations of unit cells. It can be shown that the effective stiffness and mass properties of honeycomb are controlled by the local geometry and wall thickness of the particular unit cells used. Of particular interest are regular hexagonal (6-sided) honeycomb unit cell geometries which exhibit positive effective Poisson's ratio, and modified 6-sided auxetic honeycomb unit cells with Poisson's ratio which is effectively negative; a property not found in natural materials. One important honeycomb meta-structure is sandwich composites designed with a honeycomb core bonded between two panel layers. By changing the geometry of the repetitive unit cell, and overall depth and material properties of the honeycomb core, sandwich panels with different vibration and acoustic properties can be designed to shift resonant frequencies and improve intensity and Sound Transmission Loss (STL). In the present work, a honeycomb finite element model based on beam elements is programmed in MATLAB and verified with the commercial finite element software ABAQUS for frequency extraction and direct frequency response analysis. The MATLAB program was used to study the vibration and acoustic properties of different kinds of honeycomb sandwich panels undergoing in-plane loading with different incident pressure wave angles and frequency. Results for the root mean square intensity IRMS based on normal velocity on the transmitted side of the panel measure vibration magnitude are reported for frequencies between 0 and 1000 Hz. The relationship between the sound transmission loss computed with ABAQUS and the inverse of the intensity of surface velocity is established. In the present work it is demonstrated that the general trend between the STL pressure response and the inverted intensity metric have similar response characteristics over both the stiffness frequency region and the resonance frequency region, showing that an increase in IRMS corresponds to a decrease in STL. The ABAQUS model was used to verify the MATLAB program for natural frequencies and mode shapes, and to compute the STL on the top surface of the honeycomb sandwich structure. Resonant peaks in the frequency response of intensity and STL are identified with natural frequencies and mode shapes of the honeycomb sandwich structure. A unique feature of this research is the ability to apply the time-harmonic acoustic pressure as a load on the transmitting surface of the honeycomb sandwich panel with variable incident angle ranging between 0 to 90. When the incident angle is nonzero, the pressure load is complex valued, with sinusoidal distribution, and frequency dependent. The finite element implementation of the complex-valued variable incident pressure distribution is programmed in MATLAB to give complete control of the angle, frequency and distribution. Commercial finite element software such as ABAQUS has limited ability to directly apply frequency dependent and distributed real and imaginary pressure distributions in a direct steady state frequency analysis over a large number of frequency evaluations. In the present work, IRMS results for a family of honeycomb sandwich panels with systematic increment in internal cell wall angle, subject to incremental changes in incident angle pressure loads are studied and compared. Results show that for honeycomb sandwich panels with both positive and negative internal cell wall angle, on average, intensity for the nonzero incident angles is higher than the 0 normal incident angle. For the honeycomb sandwich panels with positive internal angle, the intensity consistently increases with larger nonzero incident angles. Furthermore, under the same incident angle pressure load, the intensity of honeycomb panel with positive internal angle is consistently larger than honeycomb panels with

  5. PLLA/Flax Mat/Balsa Bio-SandwichEnvironmental Impact and Simplified Life Cycle Analysis

    NASA Astrophysics Data System (ADS)

    Le Duigou, Antoine; Deux, Jean-Marc; Davies, Peter; Baley, Christophe

    2012-06-01

    In the present paper the environmental impact of biocomposites and bio-sandwich materials production are evaluated, using simplified Life Cycle Analysis (LCA) following the procedure recommended in the ISO 14044 standard. The materials are dimensioned and evaluated by comparing with reference materials, glass mat reinforced unsatured polyester and glass mat/unsatured polyester/balsa sandwich. The results indicate that bio-sandwich materials are very attractive in terms environmental impact. However further improvements in biocomposite and bio-sandwich mechanical strength are necessary if they are to be used in transport application compared to glass/polyester and glass/polyester/balsa sandwich.

  6. Development of aircraft lavatory compartments with improved fire resistance characteristics. Phase 2: Sandwich panel resin system development

    NASA Technical Reports Server (NTRS)

    Anderson, R. A.; Arnold, D. B.; Johnson, G. A.

    1979-01-01

    A NASA-funded program is described which aims to develop a resin system for use in the construction of lavatory wall panels, sidewall panels, and ceiling panels possessing flammability, smoke and gas emission, and toxicity (FS&T) characteristics superior to the existing epoxy resin. Candidate resins studied were phenolic, polyimide, and bismaleimide. Based on the results of a series of FS&T as well as mechanical and aesthetic property tests, a phenolic resin was chosen as the superior material. Material and process specifications covering the phenolic resin based materials were prepared and a method of rating sandwich panel performance was developed.

  7. Buckling and postbuckling behavior of delaminated sandwich beams

    NASA Astrophysics Data System (ADS)

    Somers, M.; Weller, T.; Abramovich, H.

    An analytical model incorporating Griffith's energy-release rate is used in a parametric study of buckling and postbuckling behavior in sandwich beams with delaminations. The general-type model by Somers et al. (1989) is used to conduct wide-range parametric studies of beams with lengthwise and depthwise through-the width delaminations. The model describes the buckling and postbuckling response to arbitrarily situated delaminations in combination with different boundary conditions. The core-faceplate interface is shown to be area at which delaminations most readily cause premature buckling failure. Layup sequence is an important parameter for the beam's load-carrying capacity, and the boundary conditions do not significantly affect beam buckling and postbuckling. The present study is of interest to feasibility determinations of sandwich beams used in the primary structures of launch vehicles.

  8. Cryogenic optical testing of sandwich-type silicon carbide mirrors.

    PubMed

    Kaneda, Hidehiro; Onaka, Takashi; Kawada, Mitsunobu; Murakami, Hiroshi

    2003-02-01

    The experimental cryogenic performance of 160-mm-diameter silicon carbide (SiC) mirrors, one of which, a 700-mm-diameter mirror, is to be used as a primary mirror of the Japanese Infrared Astronomical Satellite ASTRO-F, is described. The mirrors are made from a sandwich-type SiC material that comprises a light porous core and a dense chemical-vapor-deposited coat of SiC. Three mirrors were manufactured consecutively, and changes in their surface contours related to temperature were measured with an interferometer when the mirrors were placed in a liquid-helium cryostat. Owing to significant improvements in manufacturing, the third SiC mirror showed only slight deformation as the temperature decreased from 300 to 6 K, which indicates high thermal strain homogeneity for a well-controlled sandwich-type SiC mirror. PMID:12564490

  9. Bismaleimide resins for flame resistant honeycomb sandwich panels

    NASA Technical Reports Server (NTRS)

    Stenzenberger, H. D.

    1978-01-01

    Bismaleimide resins are prime candidates for nonflammable aircraft interior panels. Three resin types with different structures and processing characteristics were formulated. Resin M 751 was used to fabricate 100 kg of glass fabric prepregs which were used for the preparation of face sheets for honeycomb sandwich panels. Prepreg characteristics and curing cycles for laminate fabrication are provided. In order to advance beyond the current solvent resin technology for fibre and fabric impregnation, a hot melt solvent-less resin system was prepared and characterized. Preliminary tests were performed to develop a wet bonding process for the fabrication of advanced sandwich honeycomb panels by use of polybismaleimide glass fabric face sheets and polybismaleimide Nomex honeycomb core. B-stage material was used for both the core and the face sheet, providing flatwise tensile properties equivalent to those obtained by the state-of-the-art 3-step process which includes an epoxy adhesive resin.

  10. Fatigue and impact properties of metal honeycomb sandwich panel

    NASA Astrophysics Data System (ADS)

    Zou, Guang ping; Lu, Jie; Liang, Jun; Chang, Zhong liang

    2008-11-01

    Honeycomb sandwich structures are significant to be used as applied to thermal protection system on reusable launch vehicle. In this paper the fatigue and impact properties of a novel metallic thermal protection material have been investigated and predicted at room temperature. A series of strength tests are carried out to obtain parameters firstly for further experiments. A set of tension-tension stress fatigue tests and impact tests based on split-Hopkinson pressure bar are carried out. Different high strain rate impact experiments are accomplished. The curves of dynamical stress, strain and strain rate are obtained. Also the cell units images after impact are presented. The results show the fatigue properties of honeycomb sandwich panels are comparatively better. And it has the advantages of anti-impact resistance and high, energy absorption capability.

  11. Vibration Characteristics of Partially Covered Double-Sandwich Cantilever Beam

    NASA Technical Reports Server (NTRS)

    Chen, Qinghua; Levy, Cesar

    1996-01-01

    The differential equations of motion together with the boundary conditions for a partially covered, double-sandwich cantilever beam are derived. Bending and extension, rotational and longitudinal inertia of damping layers, and shear deformation and rotational and longitudinal inertia of the constraining layers and the primary beam are included in the equations. The theory is applicable for long as well as short, soft, or stiff damping layer, double-sandwich beams. Also, the effects of different parameters on the system loss factor and resonance frequency are discussed. Differences are found to exist with the previous beam model (called the Euler beam model) when the damping layers are stiff, when the thickness of the damping layer is large compared to the primary-beam thickness, and in the case of higher modes of vibration.

  12. Impact load mitigation in sandwich beams using local resonators

    E-print Network

    Sharma, B

    2015-01-01

    Dynamic response of sandwich beams with resonators embedded in the cores subjected to impact loads is studied. Using finite element models the effectiveness of various local resonator frequencies under a given impact load is compared to the behavior of an equivalent mass beam. It is shown that addition of appropriately chosen local resonators into the sandwich beam is an effective method of improving its flexural bending behavior under impact loads. The effect of a given local resonance frequency under different impact load durations is also studied. It is demonstrated that the choice of appropriate local resonance frequency depends on the impact duration. Further, by performing transverse impact experiments, the finite element models are verified and the advantage of using internal resonators under impact loading conditions is demonstrated.

  13. Metal/dielectric/metal sandwich film for broadband reflection reduction

    PubMed Central

    Jen, Yi-Jun; Lakhtakia, Akhlesh; Lin, Meng-Jie; Wang, Wei-Hao; Wu, Huang-Ming; Liao, Hung-Sheng

    2013-01-01

    A film comprising randomly distributed metal/dielectric/metal sandwich nanopillars with a distribution of cross-sectional diameters, displayed extremely low reflectance over the blue-to-red regime, when coated on glass and illuminated normally. When it is illuminated by normally incident light, this sandwich film (SWF) has a low extinction coefficient, its phase thickness is close to a negative wavelength in the blue-to-red spectral regime, and it provides weakly dispersive forward and backward impedances, so that reflected waves from the two faces of the SWF interfere destructively. Broadband reflection-reduction, over a wide range of incidence angles and regardless of the polarization state of the incident light, was observed when the SWF was deposited on polished silicon. PMID:23591704

  14. Design of highly damage-tolerant sandwich panels

    NASA Technical Reports Server (NTRS)

    Hiel, Clement; Ishai, Ori

    1992-01-01

    The effects of different fabrication procedures to increase the damage tolerance of sandwich panels were studied. Baseline panels consisted of a 25.4 mm premolded core, surfaced with 177 C cure film adhesive and carbon-bismaleimide prepreg which were subsequently cocured onto the core. It was found that panels with a prefabricated skin, which was subsequently bonded onto the core with room temperature cure adhesive, showed greatly increased damage tolerance.

  15. QUANTITATIVE DOUBLE ANTIBODY SANDWICH ELISA FOR THE DETERMINATION OF GLIADIN

    Microsoft Academic Search

    Naiyana Gujral; Mavanur R. Suresh; Hoon H. Sunwoo

    2012-01-01

    A sensitive double antibody sandwich ELISA (DAS-ELISA) based on chicken anti-gliadin IgY and biotinylated monoclonal antibody (mAb) was developed for the quantification of gliadin in foods. The anti-gliadin IgY and mAb specifically detected gliadin in wheat, barley and rye by indirect ELISA and western-blot assay. Using anti-gliadin IgY as capture antibody and biotinylated mAb as detecting antibody, the sensitivity of

  16. Star cell type core configuration for structural sandwich materials

    DOEpatents

    Christensen, R.M.

    1995-08-01

    A new pattern for cellular core material used in sandwich type structural materials is disclosed. The new pattern involves star shaped cells intermixed with hexagonal shaped cells. The new patterned cellular core material includes star shaped cells interconnected at points thereof and having hexagonal shape cells positioned adjacent the star points. The new pattern allows more flexibility and can conform more easily to curved shapes. 3 figs.

  17. Monitoring for Heterosigma akashiwo using a sandwich hybridization assay

    Microsoft Academic Search

    John V Tyrrell; Laurie B Connell; Chris A Scholin

    2002-01-01

    Field testing of a ribosomal RNA (rRNA)-targeted sandwich hybridization assay (SHA) for Heterosigma akashiwo (Raphidophyceae) in Puget Sound, WA, USA, has showed that the lower limit of detection is well below the level at which cells pose a danger to fish. Moreover, the assay has proven to be both rapid and easy-to-use. Isolates of H. akashiwo from Australia, Japan, New

  18. Monitoring for Heterosigma akashiwousing a sandwich hybridization assay

    Microsoft Academic Search

    John V. Tyrrell; Laurie B. Connell; Chris A. Scholin

    2002-01-01

    Field testing of a ribosomal RNA (rRNA)-targeted sandwich hybridization assay (SHA) for Heterosigma akashiwo(Raphi- dophyceae) in Puget Sound, WA, USA, has showed that the lower limit of detection is well below the level at which cells pose a danger to fish. Moreover, the assay has proven to be both rapid and easy-to-use. Isolates of H. akashiwo from Australia, Japan, New

  19. Making Three-Layer Solid Electrolyte/Electrode Sandwiches

    NASA Technical Reports Server (NTRS)

    Schroeder, James E.

    1991-01-01

    Tape-casting-and-sintering process joins two ceramic materials having widely different sintering temperatures into integral sandwich structure. Layers retain their identities, without migration of constituents. Used to make three-layer structure composed of outer porous layers of strontium-doped lanthanum manganite and inner dense layer of yttria-stabilized zirconia. Structures used to make electrolytic and fuels cells with solid electrolytes for use at high temperatures. Other potential applications include oxygen pumps and oxygen sensors.

  20. Size Effects in Impact Damage of Composite Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Dobyns, Alan; Jackson, Wade

    2003-01-01

    Panel size has a large effect on the impact response and resultant damage level of honeycomb sandwich panels. It has been observed during impact testing that panels of the same design but different panel sizes will show large differences in damage when impacted with the same impact energy. To study this effect, a test program was conducted with instrumented impact testing of three different sizes of sandwich panels to obtain data on panel response and residual damage. In concert with the test program. a closed form analysis method was developed that incorporates the effects of damage on the impact response. This analysis method will predict both the impact response and the residual damage of a simply-supported sandwich panel impacted at any position on the panel. The damage is incorporated by the use of an experimental load-indentation curve obtained for the face-sheet/honeycomb and indentor combination under study. This curve inherently includes the damage response and can be obtained quasi-statically from a rigidly-backed specimen or a specimen with any support conditions. Good correlation has been obtained between the test data and the analysis results for the maximum force and residual indentation. The predictions can be improved by using a dynamic indentation curve. Analyses have also been done using the MSC/DYTRAN finite element code.

  1. Lightweight composites for modular panelized construction

    NASA Astrophysics Data System (ADS)

    Vaidya, Amol S.

    Rapid advances in construction materials technology have enabled civil engineers to achieve impressive gains in the safety, economy, and functionality of structures built to serve the common needs of society. Modular building systems is a fast-growing modern, form of construction gaining recognition for its increased efficiency and ability to apply modern technology to the needs of the market place. In the modular construction technique, a single structural panel can perform a number of functions such as providing thermal insulation, vibration damping, and structural strength. These multifunctional panels can be prefabricated in a manufacturing facility and then transferred to the construction site. A system that uses prefabricated panels for construction is called a "panelized construction system". This study focuses on the development of pre-cast, lightweight, multifunctional sandwich composite panels to be used for panelized construction. Two thermoplastic composite panels are proposed in this study, namely Composite Structural Insulated Panels (CSIPs) for exterior walls, floors and roofs, and Open Core Sandwich composite for multifunctional interior walls of a structure. Special manufacturing techniques are developed for manufacturing these panels. The structural behavior of these panels is analyzed based on various building design codes. Detailed descriptions of the design, cost analysis, manufacturing, finite element modeling and structural testing of these proposed panels are included in this study in the of form five peer-reviewed journal articles. The structural testing of the proposed panels involved in this study included flexural testing, axial compression testing, and low and high velocity impact testing. Based on the current study, the proposed CSIP wall and floor panels were found satisfactory, based on building design codes ASCE-7-05 and ACI-318-05. Joining techniques are proposed in this study for connecting the precast panels on the construction site. Keywords: Modular panelized construction, sandwich composites, composite structural insulated panels (CSIPs).

  2. Vibrational analysis of rectangular sandwich plates resting on some elastic point supports

    SciTech Connect

    Ichinomiya, Osamu; Maruyama, Koichi; Sekine, Kouji [Hokkaido Inst. of Tech., Sapporo (Japan). Dept. of Mechanical engineering

    1995-11-01

    An approximate solution of forced-vibration for rectangular sandwich plate resting on some elastic point supports is presented. The sandwich plate has thin, anisotropic composite laminated faces and a thick orthotropic core. The simplified sandwich plate model is used in the analysis. The governing equation of elastically point supported rectangular sandwich plate is obtained by using the Lagrange equation. The steady state response solution to a sinusoidally varying point force is also derived. The response curves of rectangular sandwich plates having CFRP laminated faces and aluminum honeycomb core is calculated. Application examples illustrate the effects of laminate lay-up of face sheets, core material properties and core thickness ratio on the vibration characteristics of rectangular sandwich plate.

  3. The development and evaluation of advanced Kevlar sandwich structure for application to rotorcraft airframes

    NASA Astrophysics Data System (ADS)

    Minguet, Pierre; Llorente, Steven; Fay, Russell

    1991-05-01

    The results of an evaluation of DuPont Kevlar-based material systems in sandwich structure designed for rotorcraft primary airframe structure are presented in this report. The focus of this work has been to evaluate the durability and compression strength of thin-gage Kevlar sandwich panels and investigate means of improvement. It was found that sandwich panels made with Kevlar 149 fibers can be as strong as Kevlar 49 structures but have reduced compression stiffness properties at typical operating strain levels. Thermal cycling was found to affect permeability but not strength in thin facesheet sandwich structure. Any increased permeability can be prevented with the use of an interleaf or surfacing plies. The surfacing plies investigated also had a beneficial effect on sandwich strength due to their stabilizing effect on the facesheet in compression. Finally, a previously developed model was used to analyze the residual strength of a sandwich panel after impact damage.

  4. Dynamic models for low-velocity impact damage of composite sandwich panels Part A: Deformation

    Microsoft Academic Search

    Michelle S. Hoo Fatt; Kyong S. Park

    2001-01-01

    Equivalent single and multi degree-of-freedom systems are used to predict the low-velocity impact response of rigidly supported, two-sided clamped, simply supported and four-sided clamped composite sandwich panels. The composite sandwich panels have orthotropic facesheets and are symmetric. Analytical solutions for the transient deformation response of the sandwich panels are presented in this paper, and analytical predictions of impact damage initiation

  5. Dynamic models for low-velocity impact damage of composite sandwich panels Part B: Damage initiation

    Microsoft Academic Search

    Michelle S. Hoo Fatt; Kyong S. Park

    2001-01-01

    Equivalent single and multi degree-of-freedom systems are used to predict low-velocity impact damage of composite sandwich panels by rigid projectiles. The composite sandwich panels are symmetric and consist of orthotropic laminate facesheets and a core with constant crushing resistance. The transient deformation response of the sandwich panels subjected to impact were predicted in a previous paper, and analytical solutions for

  6. The Rightful Demise of the Sh*t Sandwich: Providing Effective Feedback.

    PubMed

    James, Ian Andrew

    2014-04-01

    Background: As a trainee cognitive therapist in the early 1990s, I was taught the Sh*t Sandwich by my supervisor. I continued to use this technique for many years without seeing the need to extend my repertoire of feedback strategies. Aims: This article describes a number of other feedback techniques, raising awareness of the processes underpinning feedback, and facilitating reflection on feedback methods. Method: This review examines feedback and the methods of feedback used to improve clinical competence. Results: Evidence informs us that the use of good feedback has a significant effect on learners' outcomes (Milne, 2009). However, despite recognition of its importance, many supervisors fail to give adequate feedback and utilize methods that are sub-optimal. One such problematic method is the notorious "Sh*t Sandwich" (SS), which attempts to hide criticism within a cushion of two positive statements. This paper looks at various models of giving negative and positive feedback, suggesting that our repertoire of feedback methods may require expanding. Conclusion: The review suggests that feedback is a complex process and methods that place an emphasis on the learner as an active participant in the learning process (i.e. interactive approaches) should be encouraged. The paper suggests that negative feedback should generally be avoided in favour of constructive support, accompanied by specific, descriptive, balanced feedback, with new learning being consolidated by role play. Generally, feedback should be given about the task rather than the person, but when it is personalized it should relate to effort rather than ability. PMID:24702833

  7. Synthesis and characterization of a 1D chain-like Cu{sub 6} substituted sandwich-type phosphotungstate with pendant dinuclear Cuazido complexes

    SciTech Connect

    Li, Yan-Ying [MOE Key Laboratory of Cluster Science, School of Chemistry, Beijing Institute of Technology, Beijing 100081 (China); Zhao, Jun-Wei, E-mail: zhaojunwei@henu.edu.cn [Henan Key Laboratory of Polyoxometalate Chemistry, College of Chemistry and Chemical Engineering, Henan University, Kaifeng, Henan 475004 (China); Wei, Qi [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Yang, Bai-Feng [MOE Key Laboratory of Cluster Science, School of Chemistry, Beijing Institute of Technology, Beijing 100081 (China); Yang, Guo-Yu, E-mail: ygy@bit.edu.cn [MOE Key Laboratory of Cluster Science, School of Chemistry, Beijing Institute of Technology, Beijing 100081 (China); State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

    2014-02-15

    A novel Cuazido complex modified hexa-Cu{sup II} substituted sandwich-type phosphotungstate [Cu(en){sub 2}]([Cu{sub 2}(en){sub 2}(?-1,1-N{sub 3}){sub 2}(H{sub 2}O)]{sub 2}[Cu{sub 6}(en){sub 2}(H{sub 2}O){sub 2}(B-?-PW{sub 9}O{sub 34}){sub 2}])6H{sub 2}O (1) (en=ethylene-diamine) has been prepared under hydrothermal conditions and structurally characterized by elemental analyses, IR spectra, powder X-ray diffraction (PXRD) and single-crystal X-ray diffraction. 1 displays a beautiful 1-D chain architecture constructed from sandwich-type [Cu{sub 2}(en){sub 2}(?-1,1-N{sub 3}){sub 2}(H{sub 2}O)]{sub 2}[Cu{sub 6}(en){sub 2}(H{sub 2}O){sub 2}(B-?-PW{sub 9}O{sub 34}){sub 2}]{sup 2?} units and [Cu(en){sub 2}]{sup 2+} linkers. To our knowledge, 1 represents the first hexa-Cu{sup II} sandwiched phosphotungstate with supporting Cuazido complexes. - Graphical abstract: The first hexa-Cu{sup II} sandwiched phosphotungstate with supporting Cuazido complexes has been prepared and characterized. Display Omitted - Highlights: Hexa-copper-substituted phosphotungstate. Cuazido complexes modified hexa-Cu{sup II} substituted sandwich-type polyoxometalate. 1-D chain architecture built by hexa-copper-substituted polyoxotungstate units.

  8. Experimental evaluation of two 36 inch by 47 inch graphite/epoxy sandwich shear webs

    NASA Technical Reports Server (NTRS)

    Bush, H. G.

    1975-01-01

    The design is described and test of two large (36 in. x 47 in.) graphite/epoxy sandwich shear webs. One sandwich web was designed to exhibit strength failure of the facings at a shear load of 7638 lbs/in., which is a characteristic loading for the space shuttle orbiter main engine thrust beam structure. The second sandwich web was designed to exhibit general instability failure at a shear load of 5000 lbs/in., to identify problem areas of stability critical sandwich webs and to assess the adequacy of contemporary analysis techniques.

  9. Smart Composite Sandwich Structures for Future Aerospace Application -Damage Detection and Suppression-: a Review

    NASA Astrophysics Data System (ADS)

    Takeda, Nobuo; Minakuchi, Shu; Okabe, Yoji

    Sandwich structures with advanced composite facesheets are attracting much attention as a solution to maximize the potential of composite materials. However, the composite sandwich structures are prone to damage, such as impact damage and debonding. Although these damages are difficult to detect using conventional nondestructive inspection method, they cause significant reduction in the mechanical properties. Hence, several researchers have attempted to detect and suppress the damages using smart sensors and actuators. In this paper recent developments on smart technologies to improve reliability of the composite sandwich structures are reviewed. First, the state-of-the-art sandwich technology in aerospace application is presented. Next, typical damages in composite sandwich structures are described, which is essential to effectively apply the smart technologies to sandwich structures. Then, smart technologies which have been applied to sandwich structures are briefly shown with focusing specific properties of sandwich structures. It includes damage detection using dynamic response, wave propagation and optical fiber sensors. Finally, a smart honeycomb sandwich concept is also presented.

  10. Energy absorption capabilities of composite sandwich panels under blast loads

    NASA Astrophysics Data System (ADS)

    Sankar Ray, Tirtha

    As blast threats on military and civilian structures continue to be a significant concern, there remains a need for improved design strategies to increase blast resistance capabilities. The approach to blast resistance proposed here is focused on dissipating the high levels of pressure induced during a blast through maximizing the potential for energy absorption of composite sandwich panels, which are a competitive structural member type due to the inherent energy absorption capabilities of fiber reinforced polymer (FRP) composites. Furthermore, the middle core in the sandwich panels can be designed as a sacrificial layer allowing for a significant amount of deformation or progressive failure to maximize the potential for energy absorption. The research here is aimed at the optimization of composite sandwich panels for blast mitigation via energy absorption mechanisms. The energy absorption mechanisms considered include absorbed strain energy due to inelastic deformation as well as energy dissipation through progressive failure of the core of the sandwich panels. The methods employed in the research consist of a combination of experimentally-validated finite element analysis (FEA) and the derivation and use of a simplified analytical model. The key components of the scope of work then includes: establishment of quantified energy absorption criteria, validation of the selected FE modeling techniques, development of the simplified analytical model, investigation of influential core architectures and geometric parameters, and investigation of influential material properties. For the parameters that are identified as being most-influential, recommended values for these parameters are suggested in conceptual terms that are conducive to designing composite sandwich panels for various blast threats. Based on reviewing the energy response characteristic of the panel under blast loading, a non-dimensional parameter AET/ ET (absorbed energy, AET, normalized by total energy, ET) was suggested to compare energy absorption capabilities of the structures under blast loading. In addition, AEweb/ET (where AEweb is the energy absorbed by the middle core) was also employed to evaluate the energy absorption contribution from the web. Taking advantage of FEA and the simplified analytical model, the influences of material properties as well as core architectures and geometries on energy absorption capabilities (quantified by AET/ ET and AEweb/E T) were investigated through parametric studies. Results from the material property investigation indicated that density of the front face sheet and strength were most influential on the energy absorption capability of the composite sandwich panels under blast loading. The study to investigate the potential effectiveness of energy absorbed via inelastic deformation compared to energy absorbed via progressive failure indicated that for practical applications (where the position of bomb is usually unknown and the panel is designed to be the same anywhere), the energy absorption via inelastic deformation is the more efficient approach. Regarding the geometric optimization, it was found that a core architecture consisting of vertically-oriented webs was ideal. The optimum values for these parameters can be generally described as those which cause the most inelasticity, but not failure, of the face sheets and webs.

  11. Low Velocity Blunt Impact on Lightweight Composite Sandwich Panels

    NASA Astrophysics Data System (ADS)

    Chan, Monica Kar

    There is an increased desire to incorporate more composite sandwich structures into modern aircrafts. Because in-service aircrafts routinely experience impact damage during maintenance due to ground vehicle collision, dropped equipment, or foreign object damage (FOD) impact, it is necessary to understand their impact characteristics, particularly when blunt impact sources create internal damage with little or no external visibility. The objective of this investigation is to explore damage formation in lightweight composite sandwich panels due to low-velocity impacts of variable tip radius and energy level. The correlation between barely visible external dent formation and internal core damage was explored as a function of impact tip radius. A pendulum impactor was used to impact composite sandwich panels having honeycomb core while held in a 165 mm square window fixture. The panels were impacted by hardened steel tips with radii of 12.7, 25.4, 50.8, and 76.2 mm at energy levels ranging from 2 to 14 J. Experimental data showed little dependence of external dent depth on tip radius at very low energies of 2 to 6 J, and thus, there was also little variation in visibility due to tip radius. Four modes of internal core damage were identified. Internal damage span and depth were dependent on impact tip radius. Damage depth was also radius-dependent, but stabilized at constant depth independent of kinetic energy. Internal damage span increased with increasing impact energy, but not with increasing tip radius, suggesting a relationship between maximum damage tip radius with core density/size.

  12. Sandwich Hologram Interferometry For Determination Of Sacroiliac Joint Movements

    NASA Astrophysics Data System (ADS)

    Vukicevic, S.; Vinter, I.; Vukicevic, D.

    1983-12-01

    Investigations were carried out on embalmed and fresh specimens of human pelvisis with preserved lumbar spines, hip joints and all the ligaments. Specimens were tested under static vertical loading by pulsed laser interferometry. The deformations and behaviour of particular pelvic parts were interpreted by providing computer interferogram models. Results indicate rotation and tilting of the sacrum in the dorso-ventral direction and small but significant movements in the cranio-caudal direction. Sandwich holography proved to be the only applicable method when there is a combination of translation and tilt in the range of 200 ?m to 1.5 mm.

  13. Deformation and fracture of impulsively loaded sandwich panels

    NASA Astrophysics Data System (ADS)

    Wadley, H. N. G.; Brvik, T.; Olovsson, L.; Wetzel, J. J.; Dharmasena, K. P.; Hopperstad, O. S.; Deshpande, V. S.; Hutchinson, J. W.

    2013-02-01

    Light metal sandwich panel structures with cellular cores have attracted interest for multifunctional applications which exploit their high bend strength and impact energy absorption. This concept has been explored here using a model 6061-T6 aluminum alloy system fabricated by friction stir weld joining extruded sandwich panels with a triangular corrugated core. Micro-hardness and miniature tensile coupon testing revealed that friction stir welding reduced the strength and ductility in the welds and a narrow heat affected zone on either side of the weld by approximately 30%. Square, edge clamped sandwich panels and solid plates of equal mass per unit area were subjected to localized impulsive loading by the impact of explosively accelerated, water saturated, sand shells. The hydrodynamic load and impulse applied by the sand were gradually increased by reducing the stand-off distance between the test charge and panel surfaces. The sandwich panels suffered global bending and stretching, and localized core crushing. As the pressure applied by the sand increased, face sheet fracture by a combination of tensile stretching and shear-off occurred first at the two clamped edges of the panels that were parallel with the corrugation and weld direction. The plane of these fractures always lay within the heat affected zone of the longitudinal welds. For the most intensively loaded panels additional cracks occurred at the other clamped boundaries and in the center of the panel. To investigate the dynamic deformation and fracture processes, a particle-based method has been used to simulate the impulsive loading of the panels. This has been combined with a finite element analysis utilizing a modified Johnson-Cook constitutive relation and a Cockcroft-Latham fracture criterion that accounted for local variation in material properties. The fully coupled simulation approach enabled the relationships between the soil-explosive test charge design, panel geometry, spatially varying material properties and the panel's deformation and dynamic failure responses to be explored. This comprehensive study reveals the existence of a strong instability in the loading that results from changes in sand particle reflection during dynamic evolution of the panel's surface topology. Significant fluid-structure interaction effects are also discovered at the sample sides and corners due to changes of the sand reflection angle by the edge clamping system.

  14. Optimized analysis of geometry parameters for honeycomb sandwich mirror

    NASA Astrophysics Data System (ADS)

    Chen, Xiao'an; Cheng, Yuntao; Zeng, Qingna; Liu, Hong; Fang, Jingzhong; Rao, Changhui

    2014-07-01

    The relationship of geometry parameters, specific stiffness, surface figure and natural frequency was investigated based on modified Gibson theory, sandwich theory, Hoff theory and vibration theory. By theoretical analysis and finite element method, we demonstrated the geometric parameters had non-linear influence on dimensionless specific stiffness in different directions with the honeycomb core was equivalent as modified solid material. Approximate expressions of deformation, natural frequency and geometric parameters were obtained. The results showed the optimal solidity ratio and face plate thickness ratio were in the range of 0.03 ~ 0.1 and 0.02 ~0.05, respectively.

  15. Stabilizing graphene-based organometallic sandwich structures through defect engineering

    NASA Astrophysics Data System (ADS)

    Dev, Pratibha; Reinecke, Thomas L.

    2015-01-01

    In this theoretical work, we propose a chemical route to creating stable benzene-transition metal-graphene sandwich structures. The binding energy of the transition metal to graphene is enhanced through adsorption at appropriate defects, immobilizing the metal onto the graphene web. Capping the metal with a benzene ring further stabilizes the structure. The stability and the magnetic properties of these composite structures vary for different defects such as vacancies and nitrogen substitutionals in graphene. The proposed complexes have high cohesive energies and are either metallic or are small-band-gap semiconductors. Several of the proposed structures also have large spin polarization energies that make them suitable for use as nanomagnets in ambient conditions. This work also sheds light on the experimental results in the field where the sandwich structures may have been successfully created. We show that defect engineering is a viable option for creating designer, graphene-based structures that may play an important role in fields as diverse as spintronics, nanoelectronics, hydrogen storage, and catalysis.

  16. Foam-injected sandwich panels with continuous-reinforced facings

    NASA Astrophysics Data System (ADS)

    Menrath, A.; Henning, F.; Huber, T.; Roch, A.; Riess, C.

    2014-05-01

    Thermoplastic foam injection molding (FIM) in combination with insert molding (IM) offers a possibility to generate sandwich panels in a one-step process. The prepared face sheets are first positioned inside the mold. A preheating process is carried out using quartz infrared emitters, which are mounted on a linear robot, before the mold is closed. The injection of the gas/melt mixture is combined with an embossing of the mold to further improve the face-core-adhesion. Finally, to initiate the foaming process, adjust the extent of foaming of the core and achieve the desired component dimensions, a mold opening stroke is carried out. The process described was performed with different facing materials, layer dimensions and overall wall thicknesses. Drawn PP fabrics (Curv) as well as PP/GF70 tapes and consolidated sheets (unidirectional) were used to generate sandwich panels in a range of 5 to 6.4 mm thickness. PP was also chosen to form the foamed core which, in combination with the Curv face sheets, produces a fully recyclable self-reinforced polymer (SRP) composite. Detailed process descriptions and the results of bending tests demonstrate the high potential. Other focuses are the preheating process and the foam structure.

  17. Half-sandwich iridium- and rhodium-based organometallic architectures: rational design, synthesis, characterization, and applications.

    PubMed

    Han, Ying-Feng; Jin, Guo-Xin

    2014-12-16

    CONSPECTUS: Over the last two decades, researchers have focused on the design and synthesis of supramolecular coordination complexes, which contain discrete functional structures with particular shapes and sizes, and are similar to classic metal-organic frameworks. Chemists can regulate many of these systems by judiciously choosing the metal centers and their adjoining ligands. These resulting complexes have unusual properties and therefore many applications, including molecular recognition, supramolecular catalysis, and some applications as nanomaterials. In addition, researchers have extensively developed synthetic methodologies for the construction of discrete self-assemblies. One of the most important challenges for scientists in this area is to be able to synthesize target structures that can be controlled in both length and width. For this reason, it is important that we understand the factors leading to special shapes and sizes of such architectures, especially how starting building blocks and functional ligands affect the final conformations and cavity sizes of the resulting assemblies. Towards this goal, we have developed a wide range of different organometallic architectures by rationally designing metal-containing precursors and organic ligands. In this Account, we present our recent work, focusing on half-sandwich iridium- and rhodium-based organometallic assemblies that we obtained through rational design. We discuss their synthesis, structures, and applications for the encapsulation of guests and enzyme-mimicking catalysis. We first describe a series of self-assembled organometallic metallarectangles and metallacages, which we constructed from preorganized dinuclear half-sandwich molecular clips and suitable pyridyl ligands. We extended this strategy to tune the size of the obtained rectangles, creating large cavities by introduction of larger molecular clips. The cavity was found to exhibit selective and reversible CH2Cl2 adsorption properties while retaining single crystallinity. By using suitable molecular clips, we found we could use a number of metallacycles as organometallic templates to direct photochemical [2 + 2] cycloaddition reactions, even in the solid state. Due to their chemical stability and potential applications in catalytic reactions, researchers are giving significant attention to complexes with cyclometalated backbones. We also highlight our efforts to develop efficient approaches to utilize cyclometalated building blocks for the formation of organometallic assemblies. By incorporation of imine ligands or benzoic acids, bipyridine linking subunits, and half-sandwich iridium or rhodium fragments, we built up a series of cationic and neutral metallacycles through cyclometalation-driven self-assembly. In addition, we have developed an efficient route to carborane-based metallacycles, involving the exploitation of metal-induced B-H activation. The method can provide prism-like metallacages, which are efficient hosts for the recognition of planar aromatic guests. This effort provides an incentive to generate new building blocks for the construction of organometallic assemblies. Taken together, our results may lead to a promising future for the design of complicated enzyme-mimetic-catalyzed systems. PMID:25419985

  18. Response of fully backed sandwich beams to low velocity transverse impact

    Microsoft Academic Search

    M. SADIGHI; H. POURIAYEVALI; M. SAADATI

    ? Abstract This paper describes analysis of low velocity transverse impact on fully backed sandwich beams with composite faces from Eglass\\/epoxy and cores from Polyurethane or PVC. Indentation on sandwich beams has been analyzed with the existing theories and modeled with the FE code ABAQUS, also loadings have been done experimentally to verify theoretical results. Impact on fully backed has

  19. Mechanical response of carbon fiber composite sandwich panels with pyramidal truss cores

    E-print Network

    Wadley, Haydn

    Mechanical response of carbon fiber composite sandwich panels with pyramidal truss cores Tochukwu panel designs offers novel opportunities for ultralight structures. Here, pyramidal truss sandwich cores-predicts the measurements. The CFRP pyramidal cores investigated here have a similar mechanical performance to CFRP

  20. Quantitation of Rat Lacrimal Secretion: a Novel Sandwich ELISA with High Sensitivity

    E-print Network

    Quantitation of Rat Lacrimal Secretion: a Novel Sandwich ELISA with High Sensitivity SANDHYA SANGHI sensitive assay capable of monitoring tear protein secretion by small replicate cultures. To improve signicantly on current methods, a rat- and mouse-specic sandwich ELISA was developed. For this purpose, chickens

  1. Measurement of relevant elastic and damping material properties in sandwich thick-plates

    E-print Network

    Paris-Sud XI, Université de

    more experimental data to be used. Numerical modes (frequencies, dampings, and modal shapesMeasurement of relevant elastic and damping material properties in sandwich thick-plates Marc R to measure relevant elastic and damping properties of the constituents of a sandwich structure, possibly

  2. Smart Composite Sandwich Structures for Future Aerospace Application Damage Detection and Suppression: a Review

    Microsoft Academic Search

    Nobuo Takeda; Shu Minakuchi; Yoji Okabe

    2007-01-01

    Sandwich structures with advanced composite facesheets are attracting much attention as a solution to maximize the potential of composite materials. However, the composite sandwich structures are prone to damage, such as impact damage and debonding. Although these damages are difficult to detect using conventional nondestructive inspection method, they cause significant reduction in the mechanical properties. Hence, several researchers have attempted

  3. Study on the sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration

    Microsoft Academic Search

    Shuyu Lin; Hua Tian

    2008-01-01

    A sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration is studied. The transducer consists of front and back metal masses, and coaxially segmented, thickness polarized piezoelectric ceramic thin rings. For this kind of sandwich piezoelectric transducers in thickness vibration, it is required that the lateral dimension of the transducer is sufficiently large compared with its longitudinal dimension so that no

  4. Polymeric foams and sandwich composites: Material properties, environmental effects, and shear-lag modeling

    Microsoft Academic Search

    Akawut Siriruk; Y. Jack Weitsman; Dayakar Penumadu

    2009-01-01

    Marine composite sandwich structural materials, comprising of low density PVC foam core and carbon fiber reinforced vinyl ester based resin composite facings, are studied for associated degradation in mechanical behavior caused by sea water. This paper presents experimental and analytical results concerning the properties and response of closed cell polymeric foams (PVC H100) and their sandwich composites. Data regarding the

  5. Effect of sea environment on interfacial delamination behavior of polymeric sandwich structures

    Microsoft Academic Search

    Akawut Siriruk; Dayakar Penumadu; Y. Jack Weitsman

    2009-01-01

    Sandwich structures are utilized in naval craft and thereby are exposed to sea water environment and temperature fluctuations over extended periods. The sandwich layup consists of a closed cell polymeric foam layer placed between thin carbon or glass fiber reinforced polymeric composite facings. Attention in this paper is focused on sea water effects on the interfacial mechanical response between foam

  6. Natural Cork Agglomerate Employed as an Environmentally Friendly Solution for Quiet Sandwich Composites

    PubMed Central

    Sargianis, James; Kim, Hyung-ick; Suhr, Jonghwan

    2012-01-01

    Carbon fiber-synthetic foam core sandwich composites are widely used for many structural applications due to their superior mechanical performance and low weight. Unfortunately these structures typically have very poor acoustic performance. There is increasingly growing demand in mitigating this noise issue in sandwich composite structures. This study shows that marrying carbon fiber composites with natural cork in a sandwich structure provides a synergistic effect yielding a noise-free sandwich composite structure without the sacrifice of mechanical performance or weight. Moreover the cork-core sandwich composites boast a 250% improvement in damping performance, providing increased durability and lifetime operation. Additionally as the world seeks environmentally friendly materials, the harvesting of cork is a natural, renewable process which reduces subsequent carbon footprints. Such a transition from synthetic foam cores to natural cork cores could provide unprecedented improvements in acoustic and vibrational performance in applications such as aircraft cabins or wind turbine blades. PMID:22574250

  7. Natural cork agglomerate employed as an environmentally friendly solution for quiet sandwich composites.

    PubMed

    Sargianis, James; Kim, Hyung-ick; Suhr, Jonghwan

    2012-01-01

    Carbon fiber-synthetic foam core sandwich composites are widely used for many structural applications due to their superior mechanical performance and low weight. Unfortunately these structures typically have very poor acoustic performance. There is increasingly growing demand in mitigating this noise issue in sandwich composite structures. This study shows that marrying carbon fiber composites with natural cork in a sandwich structure provides a synergistic effect yielding a noise-free sandwich composite structure without the sacrifice of mechanical performance or weight. Moreover the cork-core sandwich composites boast a 250% improvement in damping performance, providing increased durability and lifetime operation. Additionally as the world seeks environmentally friendly materials, the harvesting of cork is a natural, renewable process which reduces subsequent carbon footprints. Such a transition from synthetic foam cores to natural cork cores could provide unprecedented improvements in acoustic and vibrational performance in applications such as aircraft cabins or wind turbine blades. PMID:22574250

  8. High renewable content sandwich structures based on flax-basalt hybrids and biobased epoxy polymers

    NASA Astrophysics Data System (ADS)

    Colomina, S.; Boronat, T.; Fenollar, O.; Snchez-Nacher, L.; Balart, R.

    2014-05-01

    In the last years, a growing interest in the development of high environmental efficiency materials has been detected and this situation is more accentuated in the field of polymers and polymer composites. In this work, green composite sandwich structures with high renewable content have been developed with core cork materials. The base resin for composites was a biobased epoxy resin derived from epoxidized vegetable oils. Hybrid basalt-flax fabrics have been used as reinforcements for composites and the influence of the stacking sequence has been evaluated in order to optimize the appropriate laminate structure for the sandwich bases. Core cork materials with different thickness have been used to evaluate performance of sandwich structures thus leading to high renewable content composite sandwich structures. Results show that position of basalt fabrics plays a key role in flexural fracture of sandwich structures due to differences in stiffness between flax and basalt fibers.

  9. PLLA/Flax Mat/Balsa Bio-Sandwich Manufacture and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Le Duigou, Antoine; Deux, Jean-Marc; Davies, Peter; Baley, Christophe

    2011-10-01

    This paper describes the manufacture and mechanical characterization of a sandwich material which is 100% bio-sourced. The flax mat/PLLA facings and balsa core can also be composted at end of service life. Manufacture is by vacuum bag moulding. The optimum moulding time and temperature are a compromise between ensuring good impregnation and avoiding degradation, and holding for 60 min at 180C was found to be satisfactory. The mechanical properties of the bio-sandwich obtained are compared to those of a traditional glass reinforced polyester balsa sandwich. The flexural strength is 30% lower, as predicted based on the facing properties. Skin/core adhesion is also measured using debonding tests. Crack propagation occurs at the skin/core interface in the traditional sandwich but within the facing in the bio-sandwich. The impregnation of the core in the two materials is examined using X-ray micro-tomography.

  10. A Novel Sandwich Electrochemical Immunosensor Based on the DNA-Derived Magnetic Nanochain Probes for Alpha-Fetoprotein

    PubMed Central

    Gan, Ning; Jia, Liyong; Zheng, Lei

    2011-01-01

    One novel electrochemical immunosensor was constructed by immobilizing capture antibody of alpha-fetoprotein (AFP Ab1) on a nafion/nanogold-particle modified glassy carbon electrode. With a sandwich immunoassay, one DNA-derived magnetic nanoprobe, simplified as DNA/(ZMPsHRP-AFP Ab2)n, was employed for the detection of AFP. The fabricated procedure of the proposed biosensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The performance and factors influencing the performance of the biosensor were also evaluated. Under optimal conditions, the developed biosensor exhibited a well-defined electrochemical behavior toward the reduction of AFP ranging from 0.01 to 200?ng/mL with a detection limit of 4?pg/mL (S/N = 3). The biosensor was applied to the determination of AFP in serum with satisfactory results. It is important to note that the sandwich nanochainmodified electro-immunosensor provided an alternative substrate for the immobilization of other tumor markers. PMID:22013390

  11. Predicting The Compression Strength Of Impact-Damaged Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James; Jackson, Wade; Schaff, Jeffery

    1990-01-01

    The objective of this work was to develop a technique for predicting the residual compression strength of sandwich panels containing impact damage in one facesheet. The technique was tailored to predict the strength of specimens that exhibit a failure mode involving the formation of kink bands at locations of peak strain in the region of impact damage. Under continued compression loading, the kink bands propagate in a stable manner perpendicular to the applied load. When a critical kink-band length is reached, growth becomes unstable corresponding to panel failure. The analysis follows in two sections. The first section calculates the far-field stress required for stable kink-band growth and the second calculates that required for unstable growth. The residual strength prediction is made when the stress for stable growth becomes equal to that for unstable kink-band growth. Initial comparisons between analysis and experiment show good agreement.

  12. Small bending and stretching of sandwich-type shells

    NASA Technical Reports Server (NTRS)

    Reissner, Eric

    1950-01-01

    A theory has been developed for small bending and stretching of sandwich-type shells. This theory is an extension of the known theory of homogeneous thin elastic shells. It was found that two effects are important in the present problem, which are not normally of importance in the theory of curved shells: (1) the effect of transverse shear deformation and (2) the effect of transverse normal stress deformation. The first of these two effects has been known to be of importance in the theory of plates and beams. The second effect was found to occur in a manner which is typical for shells and has no counterpart in flat-plate theory. The general results of this report have been applied to the solution of problems concerning flat plates, circular rings, circular cylindrical shells, and spherical shells. In each case numerical examples have been given, illustrating the magnitude of the effects of transverse shear and normal stress deformation.

  13. Detection of bound residues in soils by sandwich-immunoassay

    SciTech Connect

    Dosch, M.; Weller, M.G.; Niessner, R. [Technical Univ. of Munich (Germany). Institute of Hydrochemistry

    1995-12-31

    Immunoassays are useful analytical instruments for the detection of many environmental compounds. This method was not introduced for the detection of non-extractable compounds in soil. So-called ``bound residues`` consist of a soil component, e.g. humic acids and an irreversibly bound pollutant. Because of the complexity of those macromolecules conventional analytical methods in general do not work. Enzyme immunoassays, in contrast, seem to have a large potential for applications and further developments in this field. The use of antibodies with high affinity to the analytes makes a selective detection of environmental pollutants possible. With the development of an enzyme-labeled sandwich-immunoassay polycyclic aromatic hydrocarbons (PAHs) irreversibly bound to humic acids were determined for the first time.

  14. Effects of Impact Damage in Midplane Asymmetric Sandwich Composites

    NASA Technical Reports Server (NTRS)

    Meador, Michael (Technical Monitor); Webb, M. Mensah; Veezie, David R.

    2003-01-01

    Several structural sandwich composites arc in service on military and commercial aerospace vehicles, however, these components have been limited to secondary structures partly because the impact damage and damage tolerance of these composites have not been extensively characterized. To improve durability, safety, and life cycle performance of PMCs while reducing maintenance costs, combined analysis, and test methods that provide a means of predicting critical engineering properties after impact damage of the structure, must be developed. A key enabling technology here is the establishment of the correlation between the impact test results conducted in the laboratory and the mechanics-based phenomenological solutions. This research was undertaken to investigate the compression and flexural properties following low velocity impact of a nomex/phenolic honeycomb core, fiberglass/epoxy facesheet, midplane asymmetric sandwich composite. One facesheet (thin side) was composed of two plies of the fiberglass/epoxy (0/90), while the other facesheet (thick side) was composed of four plies (0/90/0/90) of fiberglass/epoxy. Due to the differences in facesheet thickness, impact damage was separately induced on the thick side as well as the thin side. The compression and flexural strength properties for each damage arrangement were compared using different levels of impact energy ranging from 0 to 452 Joules. In all cases, higher impact energy resulted in decreased compression and flexural strength. Impact on the thin side showed slightly more retention of compression strength at low impact levels, whereas higher residual compressive strength was observed from impact on the thick side at higher impact levels. Different facesheet thicknesses or midplane asymmetry, played an important role in the flexural strength, however, low velocity impact on the both the thick and thin fiberglass/epoxy facesheet side showed an almost linear loss of flexural strength to saturation.

  15. Probabilistic Structural Evaluation of Uncertainties in Radiator Sandwich Panel Design

    NASA Technical Reports Server (NTRS)

    Kuguoglu, Latife; Ludwiczak, Damian

    2006-01-01

    The Jupiter Icy Moons Orbiter (JIMO) Space System is part of the NASA's Prometheus Program. As part of the JIMO engineering team at NASA Glenn Research Center, the structural design of the JIMO Heat Rejection Subsystem (HRS) is evaluated. An initial goal of this study was to perform sensitivity analyses to determine the relative importance of the input variables on the structural responses of the radiator panel. The desire was to let the sensitivity analysis information identify the important parameters. The probabilistic analysis methods illustrated here support this objective. The probabilistic structural performance evaluation of a HRS radiator sandwich panel was performed. The radiator panel structural performance was assessed in the presence of uncertainties in the loading, fabrication process variables, and material properties. The stress and displacement contours of the deterministic structural analysis at mean probability was performed and results presented. It is followed by a probabilistic evaluation to determine the effect of the primitive variables on the radiator panel structural performance. Based on uncertainties in material properties, structural geometry and loading, the results of the displacement and stress analysis are used as an input file for the probabilistic analysis of the panel. The sensitivity of the structural responses, such as maximum displacement and maximum tensile and compressive stresses of the facesheet in x and y directions and maximum VonMises stresses of the tube, to the loading and design variables is determined under the boundary condition where all edges of the radiator panel are pinned. Based on this study, design critical material and geometric parameters of the considered sandwich panel are identified.

  16. Combined compressive and shear buckling analysis of hypersonic aircraft sandwich panels

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Jackson, Raymond H.

    1992-01-01

    The combined-load (compression and shear) buckling equations were established for orthotropic sandwich panels by using the Rayleigh-Ritz method to minimize the panel total potential energy. The resulting combined-load buckling equations were used to generate buckling interaction curves for super-plastically-formed/diffusion-bonded titanium truss-core sandwich panels and titanium honeycomb-core sandwich panels having the same specific weight. The relative combined-load buckling strengths of these two types of sandwich panels are compared with consideration of their sandwich orientations. For square and nearly square panels of both types, the combined load always induces symmetric buckling. As the panel aspect ratios increase, antisymmetric buckling will show up when the loading is shear-dominated combined loading. The square panel (either type) has the highest combined buckling strength, but the combined load buckling strength drops sharply as the panel aspect ratio increases. For square panels, the truss-core sandwich panel has higher compression-dominated load buckling strength. However, for shear dominated loading, the square honeycomb-core sandwich panel has higher shear-dominated combined load buckling strength.

  17. Transient Dynamic Response and Failure of Sandwich Composite Structures under Impact Loading with Fluid Structure Interaction

    NASA Astrophysics Data System (ADS)

    Kwon, Y. W.; Violette, M. A.; McCrillis, R. D.; Didoszak, J. M.

    2012-12-01

    The objective of this study is to examine the Fluid Structure Interaction (FSI) effect on transient dynamic response and failure of sandwich composite structures under impact loading. The primary sandwich composite used in this study consisted of a 6.35 mm balsa core and a multi-ply symmetrical plain weave 6 oz E-glass skin. Both clamped sandwich composite plates and beams were studied using a uniquely designed vertical drop-weight testing machine. There were three impact conditions on which these experiments focused. The first of these conditions was completely dry (or air surrounded) testing. The second condition was completely water submerged. The final condition was also a water submerged test with air support at the backside of the plates. The tests were conducted sequentially, progressing from a low to high drop height to determine the onset and spread of damage to the sandwich composite when impacted with the test machine. The study showed the FSI effect on sandwich composite structures is very critical such that impact force, strain response, and damage size are generally much greater with FSI under the same impact condition. As a result, damage initiates at much lower impact energy conditions with the effect of FSI. Neglecting to account for FSI effects on sandwich composite structures results in very non-conservative analysis and design. Additionally, it was observed that the damage location changed for sandwich composite beams with the effect of FSI.

  18. Combined compressive and shear buckling analysis of hypersonic aircraft structural sandwich panels

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Jackson, Raymond H.

    1991-01-01

    The combined-load (compression and shear) buckling equations were established for orthotropic sandwich panels by using the Rayleigh-Ritz method to minimize the panel total potential energy. The resulting combined-load buckling equations were used to generate buckling interaction curves for super-plastically-formed/diffusion-bonded titanium truss-core sandwich panels and titanium honeycomb-core sandwich panels having the same specific weight. The relative combined-load buckling strengths of these two types of sandwich panels are compared with consideration of their sandwich orientations. For square and nearly square panels of both types, the combined load always induces symmetric buckling. As the panel aspect ratios increase, antisymmetric buckling will show up when the loading is shear-dominated combined loading. The square panel (either type) has the highest combined buckling strength, but the combined load buckling strength drops sharply as the panel aspect ratio increases. For square panels, the truss-core sandwich panel has higher compression-dominated combined load buckling strength. However, for shear dominated loading, the square honeycomb-core sandwich panel has higher shear-dominated combined load buckling strength.

  19. Damage-Tolerance Characteristics of Composite Fuselage Sandwich Structures with Thick Facesheets

    NASA Technical Reports Server (NTRS)

    McGowan, David M.; Ambur, Damodar R.

    1997-01-01

    Damage tolerance characteristics and results from experimental and analytical studies of a composite fuselage keel sandwich structure subjected to low-speed impact damage and discrete-source damage are presented. The test specimens are constructed from graphite-epoxy skins borided to a honeycomb core, and they are representative of a highly loaded fuselage keel structure. Results of compression-after-impact (CAI) and notch-length sensitivity studies of 5-in.-wide by 10-in.long specimens are presented. A correlation between low-speed-impact dent depth, the associated damage area, and residual strength for different impact-energy levels is described; and a comparison of the strength for undamaged and damaged specimens with different notch-length-to-specimen-width ratios is presented. Surface strains in the facesheets of the undamaged specimens as well as surface strains that illustrate the load redistribution around the notch sites in the notched specimens are presented and compared with results from finite element analyses. Reductions in strength of as much as 53.1 percent for the impacted specimens and 64.7 percent for the notched specimens are observed.

  20. Open-sandwich immunoassay for sensitive and broad-range detection of a shellfish toxin gonyautoxin.

    PubMed

    Hara, Yuko; Dong, Jinhua; Ueda, Hiroshi

    2013-09-01

    At present, the analytical method for paralytic shellfish poisoning (PSP) toxins in shellfish is the mouse bioassay (MBA), which is an official method of the Association of Analytical Communities (AOAC [8]). However, the low sensitivity and concerns over the number of live animals required for testing have been cited as the major reason for seeking its replacement. In this report, we employed an open-sandwich immunoassay (OS-IA) to detect gonyautoxin (GTX2/3), a kind of PSP toxins. OS-IA, which utilizes the antigen-induced enhancement of antibody VH/VL interaction, can measure a small molecule antigen in a noncompetitive format. Hence it has a wider working range and shorter measurement time. We isolated anti-GTX2/3 antibody gene from a hybridoma GT-13A by screening a Fab-displaying phage library. Then the vectors for OS-IA were constructed, and examined for antigen concentration-dependency of the VH/VL interaction by OS-ELISA. As a result, in each case, signal intensity increases notably in a wide concentration range (0.1 to >1000 ng mL(-1)) of free GTX2/3, which was enough to cover its regulation value (80 ?g 100 g(-1)) in many countries. So OS-IA will be widely applicable to detect PSP toxins in shellfish meats and in drinking water. PMID:23953213

  1. PRICE 10s 6d NETThe Elastic Stability of Sandwich Plates BY

    E-print Network

    D. C. Ae; A. F. R. Ae. S; D. C. Ae; A. F. R. Ae. S

    Swmmary.-This paper treats the elastic stability of supported rectangular plates of sandwich construction with isotropic and aeolotropic fillings under compression and shear loading. Formulae are developed for critical stresses for flat and curved panels in compression and flat panels in shear for the buckling of the whole panel, also for the wrinkling or local failure of the faces of flat panels in compression. It is established that for a wide range of conditions the critical stress for panels buckling in compression is independent of the form of the filling providing it is symmetrical about the normal; of the elastic constants of the filling only the transverse shear is of concern. As a result a simple extension of the equivalent plate theory of greatly improved accuracy is developed enabling the use of equations treating the plate as a whole. NOTE: This paper was presented as a thesis for the Diploma of the College of Aeronautics, June 1948. 1. Summary of Results.-An isotropic and two forms of aeolotropic filling are considered. Of the latter both are symmetrical about the normal to the panel?, but one has stiffnesses only in normal planes and the other has comparable stiffnesses in all planes: the first of these will be referred to as a honeycomb filling, as a fabricated paper honeycomb filling is a good example of the material in mind, and the other simply as aeolotropic. Failure may be either a buckling of the panel as a whole or a short-wave buckling or wrinkling

  2. Effect of gamma irradiation on Listeria monocytogenes in frozen, artificially contaminated sandwiches.

    PubMed

    Clardy, S; Foley, D M; Caporaso, F; Calicchia, M L; Prakash, A

    2002-11-01

    Gamma irradiation has been shown to effectively control L monocytogenes in uncooked meats but has not been extensively studied in ready-to-eat foods. The presence of Listeria in ready-to-eat foods is often due to postprocess contamination by organisms in the food-manufacturing environment. Because gamma irradiation is applied after products are packaged, the treated foods are protected from environmental recontamination. Currently, a petition to allow gamma irradiation of ready-to-eat foods is under review by the Food and Drug Administration. This study was conducted to determine if gamma irradiation could be used to control L. monocytogenes in ready-to-eat sandwiches. Ham and cheese sandwiches were contaminated with L. monocytogenes, frozen at -40 degrees C, and exposed to gamma irradiation. Following irradiation, sandwiches were assayed for L. monocytogenes. A triangle test was performed to determine if irradiated and nonirradiated sandwiches differed in sensory quality. We found that the D10-values ranged from 0.71 to 0.81 kGy and that a 5-log reduction would require irradiation with 3.5 to 4.0 kGy. The results of a 39-day storage study of sandwiches inoculated with 10(7) CFU of L monocytogenes per g indicated that counts for nonirradiated sandwiches remained fairly constant. Counts for sandwiches treated with 3.9 kGy decreased by 5 log units initially and then decreased further during storage at 4 degrees C. Sensory panelists could distinguish between irradiated and nonirradiated sandwiches but were divided on whether irradiation adversely affected sandwich quality. Our results suggest that manufacturers of ready-to-eat foods could use gamma irradiation to control L. monocytogenes and improve the safety of their products. PMID:12430695

  3. The Pleural Sandwich Sign in Two Cases of Primary Pleural Lymphoma

    PubMed Central

    Lee, Myungjae; Ryu, Yon Ju; Cho, Min-Sun

    2015-01-01

    The sandwich sign is used to describe mesenteric lymphoma in which mesenteric vessels and fat are enveloped by enlarged mesenteric lymph nodes. We present two cases of primary pleural lymphoma demonstrating the "pleural sandwich sign". Contrast-enhanced computed tomography showed conglomerated parietal pleural and extrapleural masses encasing the intercostal arteries. Histopathological examinations confirmed low grade marginal zone B-cell lymphoma in an 80-year-old man and diffuse large B-cell lymphoma in a 68-year-old man. The pleural sandwich sign may suggest the diagnosis of primary pleural lymphoma. PMID:25598693

  4. Response of Honeycomb Core Sandwich Panel with Minimum Gage GFRP Face-Sheets to Compression Loading After Impact

    NASA Technical Reports Server (NTRS)

    McQuigg, Thomas D.; Kapania, Rakesh K.; Scotti, Stephen J.; Walker, Sandra P.

    2011-01-01

    A compression after impact study has been conducted to determine the residual strength of three sandwich panel constructions with two types of thin glass fiber reinforced polymer face-sheets and two hexagonal honeycomb Nomex core densities. Impact testing is conducted to first determine the characteristics of damage resulting from various impact energy levels. Two modes of failure are found during compression after impact tests with the density of the core precipitating the failure mode present for a given specimen. A finite element analysis is presented for prediction of the residual compressive strength of the impacted specimens. The analysis includes progressive damage modeling in the face-sheets. Preliminary analysis results were similar to the experimental results; however, a higher fidelity core material model is expected to improve the correlation.

  5. Analysis and Tests of Reinforced Carbon-Epoxy/Foam-Core Sandwich Panels with Cutouts

    NASA Technical Reports Server (NTRS)

    Baker, Donald J.; Rogers, Charles

    1996-01-01

    The results of a study of a low-cost structurally efficient minimum-gage shear-panel design that can be used in light helicopters are presented. The shear-panel design is based on an integrally stiffened syntactic-foam stabilized-skin with an all-bias-ply tape construction for stabilized-skin concept with an all-bias-ply tape construction for the skins. This sandwich concept is an economical way to increase the panel bending stiffness weight penalty. The panels considered in the study were designed to be buckling resistant up to 100 lbs/in. of shear load and to have an ultimate strength of 300 lbs/in. The panel concept uses unidirectional carbon-epoxy tape on a syntactic adhesive as a stiffener that is co-cured with the skin and is an effective concept for improving panel buckling strength. The panel concept also uses pultruded carbon-epoxy rods embedded in a syntactic adhesive and over-wrapped with a bias-ply carbon-epoxy tape to form a reinforcing beam which is an effective method for redistributing load around rectangular cutout. The buckling strength of the reinforced panels is 83 to 90 percent of the predicted buckling strength based on a linear buckling analysis. The maximum experimental deflection exceeds the maximum deflection predicted by a nonlinear analysis by approximately one panel thickness. The failure strength of the reinforced panels was two and a half to seven times of the buckling strength. This efficient shear-panel design concept exceeds the required ultimate strength requirement of 300 lbs/in by more than 100 percent.

  6. ANALYSES OF DEFORMATION IN VISCOELASTIC SANDWICH COMPOSITES SUBJECT TO MOISTURE DIFFUSION

    E-print Network

    Joshi, Nikhil P.

    2010-01-16

    Sandwich composites with polymer foam core are currently used in load-bearing components in buildings and naval structures due to their high strength to weight and stiffness to weight ratios, excellent thermal insulation, and ease of manufacturing...

  7. Your Deli Sandwich May Come with A Side of Listeria, Study Finds

    MedlinePLUS

    ... Deli Sandwich May Come With a Side of Listeria, Study Finds Nearly 1 in 10 samples from ... February 11, 2015 Related MedlinePlus Pages Foodborne Illness Listeria Infections WEDNESDAY, Feb. 11, 2015 (HealthDay News) -- The ...

  8. A variable transverse stiffness sandwich structure using fluidic flexible matrix composites (F2MC)

    NASA Astrophysics Data System (ADS)

    Li, Suyi; Lotfi, Amir; Shan, Ying; Wang, K. W.; Rahn, Christopher D.; Bakis, Charles E.

    2008-03-01

    Presented in this paper is the development of a novel honeycomb sandwich panel with variable transverse stiffness. In this structure, the traditional sandwich face sheets are replaced by the fluidic flexible matrix composite (F2MC) tube layers developed in recent studies. The F2MC layers, combined with the anisotropic honeycomb core material properties, provide a new sandwich structure with variable stiffness properties for transverse loading. In this research, an analytical model is derived based on Lekhitskii's anisotropic pressurized tube solution and Timoshenko beam theory. Experimental investigations are also conducted to verify the analytical findings. A segmented multiple-F2MC-tube configuration is synthesized to increase the variable stiffness range. The analysis shows that the new honeycomb sandwich structure using F2MC tubes of 10 segments can provide a high/low transverse stiffness ratio of 60. Segmentation and stiffness control can be realized by an embedded valve network, granting a fast response time.

  9. Experimental investigation of the accuracy of a vibroacoustic model for sandwich-composite panels.

    PubMed

    Cherif, Raef; Atalla, Noureddine

    2015-03-01

    This paper presents a detailed experimental validation of a general laminate model to predict the vibroacoustic behavior of flat sandwich-composite panels. The accuracy of the model is investigated using a thin and a thick sandwich panel over a large frequency band. Several indicators are compared including the structural wavenumber, modal density, damping loss factor, radiation efficiency, and sound transmission loss. The accuracy of a simpler model based on identifying effective properties of an equivalent orthotropic panel from the General Laminate Model is also discussed. Results show that the vibroacoustic behaviors of flat sandwich-composite panels are accurately estimated using the used model and compare well to the equivalent panel model (for total transmission loss). This experimental investigation is generic and can be used as a benchmark to validate other sandwich models. PMID:25786964

  10. An Investigation on Low Velocity Impact Response of Multilayer Sandwich Composite Structures

    PubMed Central

    Jedari Salami, S.; Sadighi, M.; Shakeri, M.; Moeinfar, M.

    2013-01-01

    The effects of adding an extra layer within a sandwich panel and two different core types in top and bottom cores on low velocity impact loadings are studied experimentally in this paper. The panel includes polymer composite laminated sheets for faces and the internal laminated sheet called extra layer sheet, and two types of crushable foams are selected as the core material. Low velocity impact tests were carried out by drop hammer testing machine to the clamped multilayer sandwich panels with expanded polypropylene (EPP) and polyurethane rigid (PUR) in the top and bottom cores. Local displacement of the top core, contact force and deflection of the sandwich panel were obtained for different locations of the internal sheet; meanwhile the EPP and PUR were used in the top and bottom cores alternatively. It was found that the core material type has made significant role in improving the sandwich panel's behavior compared with the effect of extra layer location. PMID:24453804

  11. A generic sandwich-type biosensor with nanomolar detection limits.

    PubMed

    Baeumner, Antje J; Jones, Caroline; Wong, Ching Yee; Price, Andrew

    2004-03-01

    A quantitative and highly sensitive, yet simple and rapid, biosensor system was developed for the detection of nucleic acid sequences that can also be adapted to the detection of antigens. A dipstick-type biosensor with liposome amplification, based on a sandwich assay format with optical detection, was combined with a simple coupling reaction that allows the transformation of the generic biosensor components to target specific ones by a mere incubation step. This biosensor platform system was developed and optimized, and its principle was proven using DNA oligonucleotides that provided a nucleic acid biosensor for the specific detection of RNA and DNA sequences. However, the coupling reaction principle chosen can also be used for the immobilization of antibodies or receptor molecules, and therefore for the development of immunosensors and receptor-based biosensors. The generic biosensor consists of liposomes entrapping sulforhodamine B that are coated with streptavidin on the outside, and polyethersulfone membranes with anti-fluorescein antibodies immobilized in the detection zone. In order to transform the generic biosensor into a specific DNA/RNA biosensor, two oligonucleotides that are able to hybridize to the target sequence were labeled with a biotin and a fluorescein molecule, respectively. By simultaneously incubating the liposomes, both oligonucleotides, and the target sequence in a hybridization buffer for 20-30 min at 42 degrees C, a sandwich complex was formed. The mixture was applied to the polyethersulfone membrane. The complex was captured in the detection zone and quantified using a hand-held reflectometer. The system was tested using RNA sequences from B. anthracis, C. parvum and E. coli. Quantitation of concentrations between 10 fmol and 1000 fmol (10-1000 nM) was possible without altering any biosensor assay conditions. In addition, no changes to hybridization conditions were required when using authentic nucleic acid sequence-based amplified RNA sequences, and the generic biosensor compared favorably with those previously developed specifically for the RNA sequences. Therefore, the universal biosensor described is an excellent tool, for use in laboratories or at test sites, for rapidly investigating and quantifying any nucleic acid sequence of interest, as well as potentially any antigen of interest that can be bound by two antibodies simultaneously. PMID:15214421

  12. Analysis of factors influencing deflection in sandwich panels subjected to low-velocity impact

    Microsoft Academic Search

    N. Rajesh Mathivanan; J. Jerald; Puspita Behera

    2011-01-01

    Fiber reinforced sandwich structures typically respond very poorly to transverse impact events. This paper is an attempt to\\u000a investigate the impact response of sandwich panels subjected to low-velocity impact. Experimental investigations were carried\\u000a out on the influence of three design factors: height of fall, core thickness, and impactor mass, which are the most relevant\\u000a parameters to be considered for deflection.

  13. Prediction of the break-out noise of the cylindrical sandwich plate muffler shells

    Microsoft Academic Search

    M. L. Munjal

    1998-01-01

    Break-out noise from the shell often puts a limit on the (net) transmission loss that can be obtained from an engine exhaust muffler. One of the best ways of reducing break-out noise is use of a sandwich plate shell. This short paper presents an analytical model for prediction of transverse transmission loss of sandwich plate shells. Four-pole parameters of the

  14. Sandwich ELISA Microarrays: Generating Reliable and Reproducible Assays for High-Throughput Screens

    SciTech Connect

    Gonzalez, Rachel M.; Varnum, Susan M.; Zangar, Richard C.

    2009-05-11

    The sandwich ELISA microarray is a powerful screening tool in biomarker discovery and validation due to its ability to simultaneously probe for multiple proteins in a miniaturized assay. The technical challenges of generating and processing the arrays are numerous. However, careful attention to possible pitfalls in the development of your antibody microarray assay can overcome these challenges. In this chapter, we describe in detail the steps that are involved in generating a reliable and reproducible sandwich ELISA microarray assay.

  15. Low velocity impact of combination Kevlar\\/carbon fiber sandwich composites

    Microsoft Academic Search

    Jeremy Gustin; Aaran Joneson; Mohammad Mahinfalah; James Stone

    2005-01-01

    Impact, compression after impact, and tensile stiffness properties of carbon fiber and Kevlar combination sandwich composites were investigated in this study. The different samples consisted of impact-side facesheets having different combinations of carbon fiber\\/Kevlar and carbon fiber\\/hybrid. The bottom facesheets remained entirely carbon fiber to maintain the high overall flexural stiffness of the sandwich composite. The focus of this research

  16. Numerical modeling of impact-damaged sandwich composites subjected to compression-after-impact loading

    Microsoft Academic Search

    Thomas E. Lacy; Youngkeun Hwang

    2003-01-01

    Semi-empirical numerical models are developed for predicting the residual strength of impact-damaged sandwich composites comprised of woven fabric carbon epoxy facesheets and Nomex honeycomb cores subjected to compression-after-impact loading. Results from non-destructive inspection and destructive sectioning of damaged sandwich panels are used to establish initial conditions for damage (residual facesheet indentation, core crush dimensions, etc.) in the numerical analyses. Honeycomb

  17. RNA-based sandwich hybridisation method for detection of lactic acid bacteria in brewery samples

    Microsoft Academic Search

    Sanna Huhtamella; Marika Leinonen; Timo Nieminen; Beatrix Fahnert; Liisa Myllykoski; Antje Breitenstein; Peter Neubauer

    2007-01-01

    Recently we showed the applicability and sensitivity of the RNA-based sandwich hybridisation assay (SHA) for detection of Gram-negative cells in environmental samples [Leskel, T., Tilsala-Timisjrvi, A., Kusnetsov, J., Neubauer, P., Breitenstein, A., 2005. Sensitive genus-specific detection of Legionella by a 16S rRNA based sandwich hybridization assay. J. Microbiol. Met. 62, 167179.]. In this study the aim was to test and

  18. Transition metal sandwich molecules with large (C n , n ? 24) zigzag poly aromatic hydrocarbons

    Microsoft Academic Search

    Michael R. Philpott; Yoshiyuki Kawazoe

    2008-01-01

    Ab initio plane wave based density functional theory was used to study the electronic structure and geometry of sandwich structures MnR2 consisting of a layer of palladium metal atoms between large eclipsed pericondensed aromatic hydrocarbon molecules: ovalene C32H14, circumanthracene C40H16, circumpyrene C42H16 and circumcoronene C54H18. The analysis was guided by the results from the smaller sandwiches: Pd(C6H6)2, symmetric isomers of

  19. Using Conducting Wire at A-Sandwich Junctions to Improve the Transmission Performance of Radomes

    Microsoft Academic Search

    Yoshio Inasawa; Toshio Nishimura; Jun Tsuruta; Hiroaki Miyashita; Yoshihiko Konishi

    2008-01-01

    We present design procedures for using conducting wires in A-sandwich junctions to achieve high transmission performance; benchtest results validate the procedures. The scattering characteristics of the junction are obtained by solving the electric field integral equation of volumetric equivalent currents. The transmission performance is evaluated by subtracting the scattered fields of the same-sized A-sandwich panel in order to offset the

  20. Sandwich concept: enhancement for direct absorption measurements by laser-induced deflection (LID) technique

    NASA Astrophysics Data System (ADS)

    Mhlig, Ch.; Bublitz, S.; Paa, W.

    2012-11-01

    The new sandwich concept for absolute photo-thermal absorption measurements using the laser induced deflection (LID) technique is introduced and tested in comparison to the standard LID concept. The sandwich concept's idea is the decoupling of the optical materials for the pump and probe beams by placing a sample of investigation in between two optical (sandwich) plates. The pump beam is guided through the sample whereas the probe beams are deflected within the sandwich plates by the thermal lens that is generated by heat transfer from the irradiated sample. Electrical simulation and laser experiments reveal that using appropriate optical materials for the sandwich plates, the absorption detection limit for photo-thermally insensitive materials can be lowered by up to two orders of magnitude. Another advantage of the sandwich concept, the shrinking of the currently required minimum sample size, was used to investigate the laser induced absorption change in a Nd:YVO4 crystal at 1030nm. It was found that the absorption in Nd:YVO4 lowers due to the laser irradiation but partially recovers during irradiation breaks. Furthermore, absorption spectroscopy has been performed at two LBO crystals in the wavelength range 410...600nm to study the absorption structure around the SHG wavelengths of common high power lasers based on Neodymium doped laser crystals.

  1. An Analysis of Nondestructive Evaluation Techniques for Polymer Matrix Composite Sandwich Materials

    NASA Technical Reports Server (NTRS)

    Cosgriff, Laura M.; Roberts, Gary D.; Binienda, Wieslaw K.; Zheng, Diahua; Averbeck, Timothy; Roth, Donald J.; Jeanneau, Philippe

    2006-01-01

    Structural sandwich materials composed of triaxially braided polymer matrix composite material face sheets sandwiching a foam core are being utilized for applications including aerospace components and recreational equipment. Since full scale components are being made from these sandwich materials, it is necessary to develop proper inspection practices for their manufacture and in-field use. Specifically, nondestructive evaluation (NDE) techniques need to be investigated for analysis of components made from these materials. Hockey blades made from sandwich materials and a flat sandwich sample were examined with multiple NDE techniques including thermographic, radiographic, and shearographic methods to investigate damage induced in the blades and flat panel components. Hockey blades used during actual play and a flat polymer matrix composite sandwich sample with damage inserted into the foam core were investigated with each technique. NDE images from the samples were presented and discussed. Structural elements within each blade were observed with radiographic imaging. Damaged regions and some structural elements of the hockey blades were identified with thermographic imaging. Structural elements, damaged regions, and other material variations were detected in the hockey blades with shearography. Each technique s advantages and disadvantages were considered in making recommendations for inspection of components made from these types of materials.

  2. Mechanical properties characterization of composite sandwich materials intended for space antenna applications

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; Vannucci, Raymond D.

    1989-01-01

    The composite materials proposed for use in the Advanced Communications Technology Satellite (ACTS) program contains a new, high modulus graphite fiber as the reinforcement. A study was conducted to measure certain mechanical properties of the new fiber-reinforced material as well as of a composite-faced aluminum honeycomb sandwich structure. Properties were measured at -157, 22, and 121 C. Complete characterization of this material was not intended. Longitudinal tensile, picture-frame shear, short-beam shear, and flexural tests were performed on specimens of the composite face-sheet materials. Unidirectional, cross-plied, and quasi-isotropic fiber composite ply layup designs were fabricated and tested. These designs had been studied by using NASA's Integrated Composite Analyzer (ICAN) computer program. Flexural tests were conducted on (+/- 60/0 deg) sub s composite-faced sandwich structure material. Resistance strain gages were used to measure strains in the tensile, picture-frame, and sandwich flexural tests. The sandwich flexural strength was limited by the core strength at 157 and 22 c. The adhesive bond strength was the limiting factor at 121 C. Adhesive mechanical properties are reflected in sandwich structure flexural properties when the span-to-depth ratio is great enough to allow a significant shear effect on the load-deflection behavior of the sandwich beam. Most measured properties agreed satisfactorily with the properties predicted by ICAN.

  3. Mechanical properties characterization of composite sandwich materials intended for space antenna applications

    NASA Technical Reports Server (NTRS)

    Bowles, Kenneth J.; Vannucci, Raymond D.

    1986-01-01

    The composite materials proposed for use in the Advanced Communications Technology Satellite (ACTS) Program contains a new, high modulus graphite fiber as the reinforcement. A study was conducted to measure certain mechanical properties of the new fiber-reinforced material as well as of a composite-faced aluminum honeycomb sandwich structure. Properties were measured at -157, 22, and 121 C. Complete characterization of this material was not intended. Longitudinal tensile, picture-frame shear, short-beam shear, and flexural tests were performed on specimens of the composite face-sheet materials. Unidirectional, cross-plied, and quasi-isotropic fiber composite ply layup designs were fabricated and tested. These designs had been studied by using NASA's Integrated Composite Analyzer (ICAN) computer program. Flexural tests were conducted on (+/- 60/0 deg) sub s composite-faced sandwich structure material. Resistance strain gages were used to measure strains in the tensile, picture-frame, and sandwich flexural tests. The sandwich flexural strength was limited by the core strength at -157 and 22 C. The adhesive bond strength was the limiting factor at 121 C. Adhesive mechanical properties are reflected in sandwich structure flexural properties when the span-to-depth ratio is great enough to allow a significant shear effect on the load-deflection behavior of the sandwich beam. Most measured properties agreed satisfactorily with the properties predicted by ICAN.

  4. High Temperature Residual Properties of Carbon Fiber Composite Sandwich Panel with Pyramidal Truss Cores

    NASA Astrophysics Data System (ADS)

    Liu, Jiayi; Zhou, Zhengong; Wu, Linzhi; Ma, Li; Pan, Shidong

    2013-08-01

    A study on the mechanical property degradation of carbon fiber composite sandwich panel with pyramidal truss cores by high temperature exposure is performed. Analytical formulae for the residual bending strength of composite sandwich panel after thermal exposure are presented for possible competing failure modes. The composite sandwich panels were fabricated from unidirectional carbon/epoxy prepreg, and were exposed to different temperatures for different time. The bending properties of the exposed specimens were measured by three-point bending tests. Then the effect of high temperature exposure on the bending properties and damage mechanism were analyzed. The results have shown that the residual bending strength of composite sandwich panels decreased with increasing exposure temperature and time, which was caused by the degradation of the matrix property and fiber-matrix interface property at high temperature. The effect of thermal exposure on failure mode of composite sandwich panel was observed as well. The measured failure loads showed good agreement with the analytical predictions. It is expected that this study can provide useful information on the design and application of carbon fiber composite sandwich panel at high temperature.

  5. Quantitative double antibody sandwich ELISA for the determination of gliadin.

    PubMed

    Gujral, Naiyana; Suresh, Mavanur R; Sunwoo, Hoon H

    2012-01-01

    A sensitive double antibody sandwich ELISA (DAS-ELISA) based on chicken anti-gliadin IgY and biotinylated monoclonal antibody (mAb) was developed for the quantification of gliadin in foods. The anti-gliadin IgY and mAb specifically detected gliadin in wheat, barley, and rye by indirect ELISA and Western-blot assay. Using anti-gliadin IgY as capture antibody and biotinylated mAb as detecting antibody, the sensitivity of DAS-ELISA has a linear standard range of 4-40 ng/mL, showing that the limit of detection (LOD) corresponds to 4 ng/mL gliadin in assay buffer, equivalent to 0.8 ppm in foods. The intra-assay expressed as percentage of coefficients of variation (%CV) was 7.25% average of six food samples. The interassay precision was 9.51% in food samples. The combination of anti-gliadin IgY and biotinylated mAb in the DAS-ELISA provides a reliable, sensitive, and inexpensive tool for the detection of gliadin in gluten-free and gluten-containing food products. PMID:22963484

  6. Characterizing Facesheet/Core Disbonding in Honeycomb Core Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Rinker, Martin; Ratcliffe, James G.; Adams, Daniel O.; Krueger, Ronald

    2013-01-01

    Results are presented from an experimental investigation into facesheet core disbonding in carbon fiber reinforced plastic/Nomex honeycomb sandwich structures using a Single Cantilever Beam test. Specimens with three, six and twelve-ply facesheets were tested. Specimens with different honeycomb cores consisting of four different cell sizes were also tested, in addition to specimens with three different widths. Three different data reduction methods were employed for computing apparent fracture toughness values from the test data, namely an area method, a compliance calibration technique and a modified beam theory method. The compliance calibration and modified beam theory approaches yielded comparable apparent fracture toughness values, which were generally lower than those computed using the area method. Disbonding in the three-ply facesheet specimens took place at the facesheet/core interface and yielded the lowest apparent fracture toughness values. Disbonding in the six and twelve-ply facesheet specimens took place within the core, near to the facesheet/core interface. Specimen width was not found to have a significant effect on apparent fracture toughness. The amount of scatter in the apparent fracture toughness data was found to increase with honeycomb core cell size.

  7. ''Sandwich'' treatment for diospyrobezoar intestinal obstruction: a case report.

    PubMed

    Zheng, Yi-Xiong; Prasoon, Pankaj; Chen, Yan; Hu, Liang; Chen, Li

    2014-12-28

    Intestinal obstruction is a common clinical entity encountered in surgical practice. The objective of this report is to corroborate an atypical scenario of intestinal obstruction in a Chinese patient and to focus on the diagnosis and treatment. A 27-year-old male presented with a history of gastric pain combined with nausea and abdominal distension that had been present for 5 d. The presence of a foreign body was detected by computed tomography and observed as an abnormal density within the stomach. A diospyrobezoar was revealed during gastroscopy, the extraction of which was prevented due to its size and firmness. An endoscopic holmium laser joined with a snare was used to fragment the obstruction, which was followed by management with a conservative "sandwich" treatment strategy involving intestinal decompression with an ileus tube and Coca-Cola lavage between endoscopic lithotripsy fragmentation procedures. This strategy resulted in the successful removal of the diospyrobezoar along with multiple small bowel obstructions. The patient was discharged after abatement of symptoms. The case presented here demonstrates the implementation of a conservative, yet successful, treatment as an alternative to conventional surgical removal of intestinal obstructions. PMID:25561823

  8. Sandwich module prototype progress for space solar power

    NASA Astrophysics Data System (ADS)

    Jaffe, Paul; Hodkin, Jason; Harrington, Forest; Person, Clark; Nurnberger, Michael; Nguyen, Bang; LaCava, Susie; Scheiman, Dave; Stewart, Grant; Han, Andrew; Hettwer, Ethan; Rhoades, Daniel

    2014-02-01

    Space solar power (SSP) has been broadly defined as the collection of solar energy in space and its wireless transmission for use on earth. This approach potentially gives the benefit of provision of baseload power while avoiding the losses due to the day/night cycle and tropospheric effects that are associated with terrestrial solar power. Proponents have contended that the implementation of such systems could offer energy security, environmental, and technological advantages to those who would undertake their development. Among recent implementations commonly proposed for SSP, the modular symmetrical concentrator (MSC) and other modular concepts have received considerable attention. Each employs an array of modules for performing conversion of concentrated sunlight into microwaves or laser beams for transmission to earth. While prototypes of such modules have been designed and developed previously by several groups, none have been subjected to the challenging conditions inherent to the space environment and the possible solar concentration levels in which an array of modules might be required to operate. The research described herein details our team's efforts in the development of photovoltaic arrays, power electronics, microwave conversion electronics, and antennas for microwave-based "sandwich" module prototypes. The implementation status and testing results of the prototypes are reviewed.

  9. ''Sandwich'' treatment for diospyrobezoar intestinal obstruction: A case report

    PubMed Central

    Zheng, Yi-Xiong; Prasoon, Pankaj; Chen, Yan; Hu, Liang; Chen, Li

    2014-01-01

    Intestinal obstruction is a common clinical entity encountered in surgical practice. The objective of this report is to corroborate an atypical scenario of intestinal obstruction in a Chinese patient and to focus on the diagnosis and treatment. A 27-year-old male presented with a history of gastric pain combined with nausea and abdominal distension that had been present for 5 d. The presence of a foreign body was detected by computed tomography and observed as an abnormal density within the stomach. A diospyrobezoar was revealed during gastroscopy, the extraction of which was prevented due to its size and firmness. An endoscopic holmium laser joined with a snare was used to fragment the obstruction, which was followed by management with a conservative sandwich treatment strategy involving intestinal decompression with an ileus tube and Coca-Cola lavage between endoscopic lithotripsy fragmentation procedures. This strategy resulted in the successful removal of the diospyrobezoar along with multiple small bowel obstructions. The patient was discharged after abatement of symptoms. The case presented here demonstrates the implementation of a conservative, yet successful, treatment as an alternative to conventional surgical removal of intestinal obstructions. PMID:25561823

  10. Dispersion of Lamb waves in a honeycomb composite sandwich panel.

    PubMed

    Baid, Harsh; Schaal, Christoph; Samajder, Himadri; Mal, Ajit

    2015-02-01

    Composite materials are increasingly being used in advanced aircraft and aerospace structures. Despite their many advantages, composites are often susceptible to hidden damages that may occur during manufacturing and/or service of the structure. Therefore, safe operation of composite structures requires careful monitoring of the initiation and growth of such defects. Ultrasonic methods using guided waves offer a reliable and cost effective method for defects monitoring in advanced structures due to their long propagation range and their sensitivity to defects in their propagation path. In this paper, some of the useful properties of guided Lamb type waves are investigated, using analytical, numerical and experimental methods, in an effort to provide the knowledge base required for the development of viable structural health monitoring systems for composite structures. The laboratory experiments involve a pitch-catch method in which a pair of movable transducers is placed on the outside surface of the structure for generating and recording the wave signals. The specific cases considered include an aluminum plate, a woven composite laminate and an aluminum honeycomb sandwich panel. The agreement between experimental, numerical and theoretical results are shown to be excellent in certain frequency ranges, providing a guidance for the design of effective inspection systems. PMID:25287973

  11. Absorbable sandwich-like membrane for retinal-sheet transplantation.

    PubMed

    Hsiue, Ging-Ho; Lai, Jui-Yang; Lin, Po-Kang

    2002-07-01

    Neural retinal transplantation has great potential for the alleviation of different degenerative and hereditary retinal disorders. However, because of the fragile and soft nature of retina, retinal-sheet transplantation is relatively difficult to achieve. To overcome this difficulty, we developed a technique for lamellar tissue transplantation. Biodegradable gelatin membranes were fabricated into a sandwich and encapsulated retinal grafts for transplantation. Before transplantation, we characterized the in vivo and in vitro properties of such membranes to determine the optimal sterilization procedure, that is, a sterile membrane with suitable degradability and good mechanical properties and without cytotoxicity. Three sterilization methods were conducted, with hydrogen peroxide gas plasma (HPGP), ethylene oxide (EO), and gamma-ray irradiation (gamma). The results were compared with those of a control (no disinfection). Initial studies revealed that the gelatin membranes sterilized with HPGP or EO exhibited retinal pigment epithelium (RPE) cytotoxicity, whereas the membrane sterilized by 16.6-kGy gamma ray irradiation had no RPE cytotoxicity and had enhanced mechanical properties. In the in vivo rabbit study, implanted gelatin membranes demonstrated satisfactory biocompatibility without any inflammation. Transplanted retinal sheets survived well and developed laminar structures. Such a method using gelatin membranes for tissue transportation has great potential for future routine retinal-sheet transplantation. PMID:12001241

  12. Refined Zigzag Theory for Laminated Composite and Sandwich Plates

    NASA Technical Reports Server (NTRS)

    Tessler, Alexander; DiSciuva, Marco; Gherlone, Marco

    2009-01-01

    A refined zigzag theory is presented for laminated-composite and sandwich plates that includes the kinematics of first-order shear deformation theory as its baseline. The theory is variationally consistent and is derived from the virtual work principle. Novel piecewise-linear zigzag functions that provide a more realistic representation of the deformation states of transverse-shear-flexible plates than other similar theories are used. The formulation does not enforce full continuity of the transverse shear stresses across the plate s thickness, yet is robust. Transverse-shear correction factors are not required to yield accurate results. The theory is devoid of the shortcomings inherent in the previous zigzag theories including shear-force inconsistency and difficulties in simulating clamped boundary conditions, which have greatly limited the accuracy of these theories. This new theory requires only C(sup 0)-continuous kinematic approximations and is perfectly suited for developing computationally efficient finite elements. The theory should be useful for obtaining relatively efficient, accurate estimates of structural response needed to design high-performance load-bearing aerospace structures.

  13. Sandwiched structural panel having a bi-directional core structure

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce (Inventor)

    1995-01-01

    A structural panel assembly has a bi-directional core structure sandwiched between and secured to a pair of outer side wall members. The core structure is formed from first and second perpendicular series of elongated strip members having crenelated configurations. The strip members in the first series thereof are transversely interwoven with the strip members in the second series thereof in a manner such that crest portions of the strip members in the first series overlie and oppose trough portions of the strip members in the second series, and trough portions of the strip members in the first series underlie and oppose crest portions of the strip members in the second series. The crest portions of all of the strip members lie generally in a first plane and are secured to the inner side of one of the panel assembly outer side walls, and the trough portions of all of the strip members lie generally in a second plane and are secured to the inner side of the other panel assembly outer side wall.

  14. A quantitative exposure model simulating human norovirus transmission during preparation of deli sandwiches.

    PubMed

    Stals, Ambroos; Jacxsens, Liesbeth; Baert, Leen; Van Coillie, Els; Uyttendaele, Mieke

    2015-03-01

    Human noroviruses (HuNoVs) are a major cause of food borne gastroenteritis worldwide. They are often transmitted via infected and shedding food handlers manipulating foods such as deli sandwiches. The presented study aimed to simulate HuNoV transmission during the preparation of deli sandwiches in a sandwich bar. A quantitative exposure model was developed by combining the GoldSim and @Risk software packages. Input data were collected from scientific literature and from a two week observational study performed at two sandwich bars. The model included three food handlers working during a three hour shift on a shared working surface where deli sandwiches are prepared. The model consisted of three components. The first component simulated the preparation of the deli sandwiches and contained the HuNoV reservoirs, locations within the model allowing the accumulation of NoV and the working of intervention measures. The second component covered the contamination sources being (1) the initial HuNoV contaminated lettuce used on the sandwiches and (2) HuNoV originating from a shedding food handler. The third component included four possible intervention measures to reduce HuNoV transmission: hand and surface disinfection during preparation of the sandwiches, hand gloving and hand washing after a restroom visit. A single HuNoV shedding food handler could cause mean levels of 4318, 8137 and 187 HuNoV particles present on the deli sandwiches, hands and working surfaces, respectively. Introduction of contaminated lettuce as the only source of HuNoV resulted in the presence of 6.40.8 and 4.30.4 HuNoV on the food and hand reservoirs. The inclusion of hand and surface disinfection and hand gloving as a single intervention measure was not effective in the model as only marginal reductions of HuNoV levels were noticeable in the different reservoirs. High compliance of hand washing after a restroom visit did reduce HuNoV presence substantially on all reservoirs. The model showed that good handling practices such as washing hands after a restroom visit, hand gloving, hand disinfection and surface disinfection in deli sandwich bars were an effective way to prevent HuNoV contamination of the prepared foods, but it also demonstrated that further research is needed to ensure a better assessment of the risk of HuNoV transmission during preparation of foods. PMID:25544470

  15. A Refined Zigzag Beam Theory for Composite and Sandwich Beams

    NASA Technical Reports Server (NTRS)

    Tessler, Alexander; Sciuva, Marco Di; Gherlone, Marco

    2009-01-01

    A new refined theory for laminated composite and sandwich beams that contains the kinematics of the Timoshenko Beam Theory as a proper baseline subset is presented. This variationally consistent theory is derived from the virtual work principle and employs a novel piecewise linear zigzag function that provides a more realistic representation of the deformation states of transverse-shear flexible beams than other similar theories. This new zigzag function is unique in that it vanishes at the top and bottom bounding surfaces of a beam. The formulation does not enforce continuity of the transverse shear stress across the beam s cross-section, yet is robust. Two major shortcomings that are inherent in the previous zigzag theories, shear-force inconsistency and difficulties in simulating clamped boundary conditions, and that have greatly limited the utility of these previous theories are discussed in detail. An approach that has successfully resolved these shortcomings is presented herein. Exact solutions for simply supported and cantilevered beams subjected to static loads are derived and the improved modelling capability of the new zigzag beam theory is demonstrated. In particular, extensive results for thick beams with highly heterogeneous material lay-ups are discussed and compared with corresponding results obtained from elasticity solutions, two other zigzag theories, and high-fidelity finite element analyses. Comparisons with the baseline Timoshenko Beam Theory are also presented. The comparisons clearly show the improved accuracy of the new, refined zigzag theory presented herein over similar existing theories. This new theory can be readily extended to plate and shell structures, and should be useful for obtaining relatively low-cost, accurate estimates of structural response needed to design an important class of high-performance aerospace structures.

  16. Natural and recombinant bovine somatotropin: immunodetection with a sandwich ELISA.

    PubMed

    Castigliego, Lorenzo; Iannone, Giorgio; Grifoni, Goffredo; Rosati, Remo; Gianfaldoni, Daniela; Guidi, Alessandra

    2007-02-01

    Bovine Somatotropin (bST) is a peptide hormone secreted by the anterior pituitary gland and its recombinant form (rbST) is used for artificially boosting milk yield in cows. Identification of rbST is difficult in that there is little difference from the pituitary bST (pbST). In this work, we further studied the possibility of immunologically discriminating between rbST and pbST. With this purpose, we produced mouse monoclonal antibodies using, as antigen, a peptide mimicking the N-terminus of rbST from Monsanto (rbST-M) conjugated to keyhole limpet haemocyanin (KLH) and polyclonal antibodies in rabbits immunized with the whole bST or rbST-M. Hence, we developed a sandwich ELISA with the obtained antibodies for detection and quantification of bST in serum and compared its performance on the two worldwide commercialized rbSTs: rbST-M and rbST from LG Life Science (rbST-LG). The lowest detection limit of the assay was 0.05 ng/ml for rbST-M, 0.10 ng/ml for rbST-LG and 0.15 ng/ml for pbST. Furthermore, the assay showed the capability to amplify the signal in the presence of rbSTs, recognizing more efficiently rbST-M and rbST-LG than pbST (ECn pbST/ECn rbST: 3 and 1.6 respectively). Its employment for measuring bST levels in sera from bovines administered with rbST LG allowed us to detect exceptional values due to the treatment itself and probably further increased as a consequence of the higher affinity for rbSTs of our monoclonal antibody. PMID:16978434

  17. Experimental investigation on sandwich structure ring-type ultrasonic motor.

    PubMed

    Peng, Taijiang; Shi, Hongyan; Liang, Xiong; Luo, Feng; Wu, Xiaoyu

    2015-02-01

    This paper presents a manufacture method for a sandwich structure Ultrasonic Motor (USM) and experiment. Two pieces of rotor clamped on a stator, and a stainless steel disk-spring is bonded on the hollow rotor disk to provide the press by a nut assembled on the shaft. The stator is made of a double-side Printed-Circuit Board (PCB) which is sawed out the ring in the center and connected on the board with three legs. On each side of the ring surface, there are electrodes connected at the same position via through hole. The three layer drive circuit for sine, cosine, and ground signal is connected on the board through each leg. There are many piezoelectric components (PZT) bonded between two electrodes and fill soldering tin on each electrode. Then PZT is welded on PCB by reflow soldering. Finally, rub the gibbous soldering tin down to the position of PZT surface makes sure the surface contacts with rotor evenly. The welding process can also be completed by Surface Mounted Technology (SMT). A prototype motor is manufactured by this method. Two B03 model shapes of the stator are obtained by the finite element analysis and the optimal frequency of the motor is 56.375 kHz measured by impedance instrument. The theoretical analysis is conducted for the relationship between the revolving speed of the USM and thickness of stator ring, number of the travelling waves, PZT amplitude, frequency and the other parameters. The experiment result shows that the maximum revolving speed is 116 RPM and the maximum torque is 25 N mm, when the actuate voltage is 200 VAC. PMID:25213313

  18. Constructing Galileons

    E-print Network

    Mark Trodden

    2015-03-03

    In this plenary talk delivered at the DISCRETE 2014 conference in London, I briefly summarize the ideas behind and attractive properties of the Galileon field theories, and describe a broad class of scalar field theories that share these properties. After describing how Galileons arise, and commenting on their fascinating properties, in the latter half of the talk I focus on novel ways of constructing Galileon-like theories, using both the probe brane construction, and the coset construction.

  19. Online debonding detection in honeycomb sandwich structures using multi-frequency guided waves

    NASA Astrophysics Data System (ADS)

    Song, F.; Huang, G. L.; Hu, G. K.

    2009-07-01

    Due to the complex nature of sandwich structures, development of the online structural health monitoring system to detect damages in honeycomb sandwich panels inherently imposes many challenges. In this study, the leaky guided wave propagation in the honeycomb sandwich structures generated by piezoelectric wafer actuators/sensors is first simulated numerically based on the finite element method (FEM). In the numerical model, the real geometry of the honeycomb core is considered. To accurately detect debonding in the honeycomb sandwich structures, signal processing based on continuous wavelet transform is adopted to filter out the unwanted noise in the leaky Lamb wave signals collected from the experimental testing. A correlation analysis between the benchmark signals at the normal condition and those recorded at the debonded condition is then performed to determine the differential features due to the presence of debonding. Finally, the image of the debonding is formed by using a probability analysis. Specifically, fusing images acquired from multi-frequency leaky Lamb waves are obtained to enhance the quality of the final image of the structure. The location and size of the debonding in the honeycomb sandwich structures are estimated quantitatively.

  20. Thermostructural Behavior of a Hypersonic Aircraft Sandwich Panel Subjected to Heating on One Side

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    1997-01-01

    Thermostructural analysis was performed on a heated titanium honeycomb-core sandwich panel. The sandwich panel was supported at its four edges with spar-like substructures that acted as heat sinks, which are generally not considered in the classical analysis. One side of the panel was heated to high temperature to simulate aerodynamic heating during hypersonic flight. Two types of surface heating were considered: (1) flat-temperature profile, which ignores the effect of edge heat sinks, and (2) dome-shaped-temperature profile, which approximates the actual surface temperature distribution associated with the existence of edge heat sinks. The finite-element method was used to calculate the deformation field and thermal stress distributions in the face sheets and core of the sandwich panel. The detailed thermal stress distributions in the sandwich panel are presented, and critical stress regions are identified. The study shows how the magnitudes of those critical stresses and their locations change with different heating and edge conditions. This technical report presents comprehensive, three-dimensional graphical displays of thermal stress distributions in every part of a titanium honeycomb-core sandwich panel subjected to hypersonic heating on one side. The plots offer quick visualization of the structural response of the panel and are very useful for hot structures designers to identify the critical stress regions.

  1. Network architecture design of an agile sensing system with sandwich wireless sensor nodes

    NASA Astrophysics Data System (ADS)

    Dorvash, S.; Li, X.; Pakzad, S.; Cheng, L.

    2012-04-01

    Wireless sensor network (WSN) is recently emerged as a powerful tool in the structural health monitoring (SHM). Due to the limitations of wireless channel capacity and the heavy data traffic, the control on the network is usually not real time. On the other hand, many SHM applications require quick response when unexpected events, such as earthquake, happen. Realizing the need to have an agile monitoring system, an approach, called sandwich node, was proposed. Sandwich is a design of complex sensor node where two Imote2 nodes are connected with each other to enhance the capabilities of the sensing units. The extra channel and processing power, added into the nodes, enable agile responses of the sensing network, particularly in interrupting the network and altering the undergoing tasks for burst events. This paper presents the design of a testbed for examination of the performance of wireless sandwich nodes in a network. The designed elements of the network are the software architecture of remote and local nodes, and the triggering strategies for coordinating the sensing units. The performance of the designed network is evaluated through its implementation in a monitoring test in the laboratory. For both original Imote2 and the sandwich node, the response time is estimated. The results show that the sandwich node is an efficient solution to the collision issue in existing interrupt approaches and the latency in dense wireless sensor networks.

  2. Carbon sandwich preparation preserves quality of two-dimensional crystals for cryo-electron microscopy

    PubMed Central

    Yang, Fan; Abe, Kazuhiro; Tani, Kazutoshi; Fujiyoshi, Yoshinori

    2013-01-01

    Received 7 June 2013; accepted 21 June 2013Abstract Electron crystallography is an important method for determining the structure of membrane proteins. In this paper, we show the impact of a carbon sandwich preparation on the preservation of crystalline sample quality, using characteristic examples of two-dimensional (2D) crystals from gastric H+,K+-ATPase and their analyzed images. Compared with the ordinary single carbon support film preparation, the carbon sandwich preparation dramatically enhanced the resolution of images from flat sheet 2D crystals. As water evaporation is restricted in the carbon-sandwiched specimen, the improvement could be due to the strong protective effect of the retained water against drastic changes in the environment surrounding the specimen, such as dehydration and increased salt concentrations. This protective effect by the carbon sandwich technique helped to maintain the inherent and therefore best crystal conditions for analysis. Together with its strong compensation effect for the image shift due to beam-induced specimen charging, the carbon sandwich technique is a powerful method for preserving crystals of membrane proteins with larger hydrophilic regions, such as H+,K+-ATPase, and thus constitutes an efficient and high-quality method for collecting data for the structural analysis of these types of membrane proteins by electron crystallography. PMID:23883606

  3. Sandwich corrected standard errors in family-based genome-wide association studies.

    PubMed

    Minic?, Camelia C; Dolan, Conor V; Kampert, Maarten M D; Boomsma, Dorret I; Vink, Jacqueline M

    2015-03-01

    Given the availability of genotype and phenotype data collected in family members, the question arises which estimator ensures the most optimal use of such data in genome-wide scans. Using simulations, we compared the Unweighted Least Squares (ULS) and Maximum Likelihood (ML) procedures. The former is implemented in Plink and uses a sandwich correction to correct the standard errors for model misspecification of ignoring the clustering. The latter is implemented by fast linear mixed procedures and models explicitly the familial resemblance. However, as it commits to a background model limited to additive genetic and unshared environmental effects, it employs a misspecified model for traits with a shared environmental component. We considered the performance of the two procedures in terms of type I and type II error rates, with correct and incorrect model specification in ML. For traits characterized by moderate to large familial resemblance, using an ML procedure with a correctly specified model for the conditional familial covariance matrix should be the strategy of choice. The potential loss in power encountered by the sandwich corrected ULS procedure does not outweigh its computational convenience. Furthermore, the ML procedure was quite robust under model misspecification in the simulated settings and appreciably more powerful than the sandwich corrected ULS procedure. However, to correct for the effects of model misspecification in ML in circumstances other than those considered here, we propose to use a sandwich correction. We show that the sandwich correction can be formulated in terms of the fast ML method. PMID:24916646

  4. Compression After Impact Testing of Sandwich Structures Using the Four Point Bend Test

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Gregory, Elizabeth; Jackson, Justin; Kenworthy, Devon

    2008-01-01

    For many composite laminated structures, the design is driven by data obtained from Compression after Impact (CAI) testing. There currently is no standard for CAI testing of sandwich structures although there is one for solid laminates of a certain thickness and lay-up configuration. Most sandwich CAI testing has followed the basic technique of this standard where the loaded ends are precision machined and placed between two platens and compressed until failure. If little or no damage is present during the compression tests, the loaded ends may need to be potted to prevent end brooming. By putting a sandwich beam in a four point bend configuration, the region between the inner supports is put under a compressive load and a sandwich laminate with damage can be tested in this manner without the need for precision machining. Also, specimens with no damage can be taken to failure so direct comparisons between damaged and undamaged strength can be made. Data is presented that demonstrates the four point bend CAI test and is compared with end loaded compression tests of the same sandwich structure.

  5. The flame structure of AP/HTPB sandwiches

    NASA Astrophysics Data System (ADS)

    Chorpening, Benjamin Todd

    2000-10-01

    Ultraviolet emission imaging experiments have been used to study the combustion of sandwiches of ammonium perchlorate (AP) and hydroxyl-terminated polybutadiene (HTPB) in nitrogen at pressures up to 32 atm, with binder layers from 50 to 450 mum in thickness. An ICCD camera system has been used to image the flame emission near 310 nm, and a backlighting technique has been developed that allows determination of the corresponding surface shape during combustion. The results indicate the AP/HTPB interface regression rate of IPDI cured samples undergoing low power (100W) laser-assisted deflagration is nearly independent of the binder thickness for binders thicker than 100 mum. The pressure exponent of the regression rate is 0.31 up to 15 atm, increasing with pressure from 15 to 32 atm. Two primary regimes of flame behavior have been identified: a split flame base regime which occurs with high Peclet and Damkohler numbers, and a merged flame base regime which occurs with low Peclet and Damkohler numbers. A secondary regime, exhibiting a "lifted" flame, occurs with low Damkohler numbers and high Peclet numbers. The ultraviolet flame emissions observed in the experiments show a correspondence with the fuel-rich region of the flame, as determined with a Schvab-Zeldovich model. This is reasonable since the primary sources of ultraviolet emission in the 305--315 nm region, electronically excited OH and the CO + O reaction, are dependent on fuel related species. The growth of the fuel-rich region with increasing Peclet number, predicted by the model, is qualitatively matched by the experimental results. The predicted shrinkage of the fuel-rich region when the binder layer is diluted with fine AP is also qualitatively matched by the experiments. Comparison of the experimental results with a single-reaction model with finite rate kinetics shows a weak qualitative agreement on the influence of Damkohler number. A large increase in Damkohler number (factor of 20) leads to a strong splitting of the calculated reaction zone and a splitting of the base of the high temperature region. This seems to correspond to the splitting of the ultraviolet emission flame base observed in the experiments.

  6. Highly stable neutral and positively charged dicarbollide sandwich complexes.

    PubMed

    Nez, Rosario; Tutusaus, Oscar; Teixidor, Francesc; Vias, Clara; Sillanp, Reijo; Kiveks, Raikko

    2005-09-19

    Novel sandwich metallacarboranes commo-[3,3'-Ni(8-SMe2-1,2-C2B9H10)2] (1), commo-[3,3'-Co(8-SMe2-1,2-C2B9H10)2]+ (2+), commo-[3,3'-Ru(8-SMe2-1,2-C2B9H10)2] (4) and commo-[3,3'-Fe(8-SMe2-1,2-C2B9H10)2] (5) have been prepared by reaction of [10-SMe2-7,8-nido-C2B9H10]- with NiCl2 x 6 H2O, CoCl2, [RuCl2(dmso)4] and [FeCl2(dppe)], respectively. Reduction of 2+ with metallic Zn leads to the neutral and isolable complex commo-[3,3'-Co(8-SMe2-1,2-C2B9H10)2] (3). Theoretical calculations using the ZINDO/1 semiempirical method show three energy minima for complexes 1-3 and 5 that agree with the presence of three different rotamers in solution at low temperature, while four relative energy minima have been found for 4. The calculated rotational energy barriers for complexes 1-5 have been found in the range 5.2+/-0.2 and 11.5+/-0.2 kcal mol(-1). These values are in agreement with the experimental data calculated for complexes 2+ and 5. Only one rotamer is found in the X-ray crystal structure of complexes 1-3, while two are observed for 4. Neutral complexes 1, 3 and 4 exhibit a gauche conformation, whereas a cisoid conformation is found for the 2+ ion. Rotamers evident from X-ray diffraction studies are in agreement with the global energy minimum calculated by the ZINDO/1 method. The electrochemical studies conducted on 1, 3, 4 and 5 support the proposal that the charge-compensated ligand [10-SMe2-7,8-nido-C2B9H10]- stabilises lower oxidation states in metals than the dianionic [7,8-nido-C2B9H11]2- and even the [C5H5]- ligands. PMID:16035001

  7. Construction Technologies.

    ERIC Educational Resources Information Center

    Columbus State Community Coll., OH.

    This document contains materials developed for and about the construction technologies tech prep program of the South-Western City Schools in Ohio. Part 1 begins with a map of the program, which begins with a construction technologies program in grades 11 and 12 that leads to entry-level employment or one of five 2-year programs at a community

  8. Coupled Nel domain wall motion in sandwiched perpendicular magnetic anisotropy nanowires.

    PubMed

    Purnama, I; Kerk, I S; Lim, G J; Lew, W S

    2015-01-01

    The operating performance of a domain wall-based magnetic device relies on the controlled motion of the domain walls within the ferromagnetic nanowires. Here, we report on the dynamics of coupled Nel domain wall in perpendicular magnetic anisotropy (PMA) nanowires via micromagnetic simulations. The coupled Nel domain wall is obtained in a sandwich structure, where two PMA nanowires that are separated by an insulating layer are stacked vertically. Under the application of high current density, we found that the Walker breakdown phenomenon is suppressed in the sandwich structure. Consequently, the coupled Nel domain wall of the sandwich structure is able to move faster as compared to individual domain walls in a single PMA nanowire. PMID:25736593

  9. Coupled Nel domain wall motion in sandwiched perpendicular magnetic anisotropy nanowires

    PubMed Central

    Purnama, I.; Kerk, I. S.; Lim, G. J.; Lew, W. S.

    2015-01-01

    The operating performance of a domain wall-based magnetic device relies on the controlled motion of the domain walls within the ferromagnetic nanowires. Here, we report on the dynamics of coupled Nel domain wall in perpendicular magnetic anisotropy (PMA) nanowires via micromagnetic simulations. The coupled Nel domain wall is obtained in a sandwich structure, where two PMA nanowires that are separated by an insulating layer are stacked vertically. Under the application of high current density, we found that the Walker breakdown phenomenon is suppressed in the sandwich structure. Consequently, the coupled Nel domain wall of the sandwich structure is able to move faster as compared to individual domain walls in a single PMA nanowire. PMID:25736593

  10. Coupled Nel domain wall motion in sandwiched perpendicular magnetic anisotropy nanowires

    NASA Astrophysics Data System (ADS)

    Purnama, I.; Kerk, I. S.; Lim, G. J.; Lew, W. S.

    2015-03-01

    The operating performance of a domain wall-based magnetic device relies on the controlled motion of the domain walls within the ferromagnetic nanowires. Here, we report on the dynamics of coupled Nel domain wall in perpendicular magnetic anisotropy (PMA) nanowires via micromagnetic simulations. The coupled Nel domain wall is obtained in a sandwich structure, where two PMA nanowires that are separated by an insulating layer are stacked vertically. Under the application of high current density, we found that the Walker breakdown phenomenon is suppressed in the sandwich structure. Consequently, the coupled Nel domain wall of the sandwich structure is able to move faster as compared to individual domain walls in a single PMA nanowire.

  11. Tests of graphite/polyimide sandwich panels in uniaxial edgewise compression

    NASA Technical Reports Server (NTRS)

    Camarda, C. J.

    1980-01-01

    The local and general buckling behavior of graphite/polyimide sandwich panels simply supported along all four edges and loaded in uniaxial edgewise compression were investigated. Material properties of sandwich panel constituents (adhesive and facings) were determined from flatwise tension and sandwich beam flexure tests. Buckling specimens were 30.5 by 33 cm, had quasi-isotropic, symmetric facings, and a glass/polyimide honeycomb core. Core thicknesses were varied and three panels of each thickness were tested at room temperature to investigate failure modes and corresponding buckling loads. Specimens 0.635 cm thick failed by overall buckling at loads close to the analytically predicted buckling load; all other panels failed by face wrinkling. Results of the wrinkling tests indicated that several buckling formulas were unconservative and therefore not suitable for design purposes; a recommended wrinkling equation is presented.

  12. A Higher-Order Bending Theory for Laminated Composite and Sandwich Beams

    NASA Technical Reports Server (NTRS)

    Cook, Geoffrey M.

    1997-01-01

    A higher-order bending theory is derived for laminated composite and sandwich beams. This is accomplished by assuming a special form for the axial and transverse displacement expansions. An independent expansion is also assumed for the transverse normal stress. Appropriate shear correction factors based on energy considerations are used to adjust the shear stiffness. A set of transverse normal correction factors is introduced, leading to significant improvements in the transverse normal strain and stress for laminated composite and sandwich beams. A closed-form solution to the cylindrical elasticity solutions for a wide range of beam aspect ratios and commonly used material systems. Accurate shear stresses for a wide range of laminates, including the challenging unsymmetric composite and sandwich laminates, are obtained using an original corrected integration scheme. For application of the theory to a wider range of problems, guidelines for finite element approximations are presented.

  13. Self-healing sandwich structures incorporating an interfacial layer with vascular network

    NASA Astrophysics Data System (ADS)

    Chen, Chunlin; Peters, Kara; Li, Yulong

    2013-02-01

    A self-healing capability specifically targeted for sandwich composite laminates based on interfacial layers with built-in vascular networks is presented. The self-healing occurs at the facesheet-core interface through an additional interfacial layer to seal facesheet cracks and rebond facesheet-core regions. The efficacy of introducing the self-healing system at the facesheet-core interface is evaluated through four-point bend and edgewise compression testing of representative foam core sandwich composite specimens with impact induced damage. The self-healing interfacial layer partially restored the specific initial stiffness, doubling the residual initial stiffness as compared to the control specimen after the impact event. The restoration of the ultimate specific skin strength was less successful. The results also highlight the critical challenge in self-healing of sandwich composites, which is to rebond facesheets which have separated from the core material.

  14. Graphene oxide embedded sandwich nanostructures for enhanced Raman readout and their applications in pesticide monitoring

    NASA Astrophysics Data System (ADS)

    Zhang, Lulu; Jiang, Changlong; Zhang, Zhongping

    2013-04-01

    Analytical techniques based on surface-enhanced Raman scattering (SERS) suffer from a lack of reproducibility and reliability, thus hampering their practical applications. Herein, we have developed a SERS-active substrate based on a graphene oxide embedded sandwich nanostructure for ultrasensitive Raman signal readout. By using this novel Au@Ag NPs/GO/Au@Ag NPs sandwich nanostructure as a SERS substrate, the Raman signals of analytes were dramatically enhanced due to having plenty of hot spots on their surfaces and the unique structure of the graphene oxide sheets. These features make the sandwich nanostructured film an ideal SERS substrate to improve the sensitivity, reproducibility and reliability of the Raman readout. The sandwich nanostructure film can be applied to detect rhodamine-6G (R6G) with an enhancement factor (EF) of ~7.0 107 and the pesticide thiram in commercial grape juice with a detection limit of as low as 0.1 ?M (0.03 ppm), which is much lower than the maximal residue limit (MRL) of 7 ppm in fruit prescribed by the U.S. Environmental Protection Agency (EPA). The GO embedded sandwich nanostructure also has the ability to selectively detect dithiocarbamate compounds over other types of agricultural chemical. Furthermore, spiked tests show that the sandwich nanostructure can be used to monitor thiram in natural lake water and commercial grape juice without further treatment. In addition, the GO enhanced Raman spectroscopic technique offers potential practical applications for the on-site monitoring and assessment of pesticide residues in agricultural products and environments.Analytical techniques based on surface-enhanced Raman scattering (SERS) suffer from a lack of reproducibility and reliability, thus hampering their practical applications. Herein, we have developed a SERS-active substrate based on a graphene oxide embedded sandwich nanostructure for ultrasensitive Raman signal readout. By using this novel Au@Ag NPs/GO/Au@Ag NPs sandwich nanostructure as a SERS substrate, the Raman signals of analytes were dramatically enhanced due to having plenty of hot spots on their surfaces and the unique structure of the graphene oxide sheets. These features make the sandwich nanostructured film an ideal SERS substrate to improve the sensitivity, reproducibility and reliability of the Raman readout. The sandwich nanostructure film can be applied to detect rhodamine-6G (R6G) with an enhancement factor (EF) of ~7.0 107 and the pesticide thiram in commercial grape juice with a detection limit of as low as 0.1 ?M (0.03 ppm), which is much lower than the maximal residue limit (MRL) of 7 ppm in fruit prescribed by the U.S. Environmental Protection Agency (EPA). The GO embedded sandwich nanostructure also has the ability to selectively detect dithiocarbamate compounds over other types of agricultural chemical. Furthermore, spiked tests show that the sandwich nanostructure can be used to monitor thiram in natural lake water and commercial grape juice without further treatment. In addition, the GO enhanced Raman spectroscopic technique offers potential practical applications for the on-site monitoring and assessment of pesticide residues in agricultural products and environments. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr00631j

  15. Low-Velocity Impact Response of Sandwich Beams with Functionally Graded Core

    NASA Technical Reports Server (NTRS)

    Apetre, N. A.; Sankar, B. V.; Ambur, D. R.

    2006-01-01

    The problem of low-speed impact of a one-dimensional sandwich panel by a rigid cylindrical projectile is considered. The core of the sandwich panel is functionally graded such that the density, and hence its stiffness, vary through the thickness. The problem is a combination of static contact problem and dynamic response of the sandwich panel obtained via a simple nonlinear spring-mass model (quasi-static approximation). The variation of core Young's modulus is represented by a polynomial in the thickness coordinate, but the Poisson's ratio is kept constant. The two-dimensional elasticity equations for the plane sandwich structure are solved using a combination of Fourier series and Galerkin method. The contact problem is solved using the assumed contact stress distribution method. For the impact problem we used a simple dynamic model based on quasi-static behavior of the panel - the sandwich beam was modeled as a combination of two springs, a linear spring to account for the global deflection and a nonlinear spring to represent the local indentation effects. Results indicate that the contact stiffness of thc beam with graded core Increases causing the contact stresses and other stress components in the vicinity of contact to increase. However, the values of maximum strains corresponding to the maximum impact load arc reduced considerably due to grading of thc core properties. For a better comparison, the thickness of the functionally graded cores was chosen such that the flexural stiffness was equal to that of a beam with homogeneous core. The results indicate that functionally graded cores can be used effectively to mitigate or completely prevent impact damage in sandwich composites.

  16. Systems, Apparatuses, and Methods for Using Durable Adhesively Bonded Joints for Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Smeltzer, III, Stanley S. (Inventor); Lundgren, Eric C. (Inventor)

    2014-01-01

    Systems, methods, and apparatus for increasing durability of adhesively bonded joints in a sandwich structure. Such systems, methods, and apparatus includes an first face sheet and an second face sheet as well as an insert structure, the insert structure having a first insert face sheet, a second insert face sheet, and an insert core material. In addition, sandwich core material is arranged between the first face sheet and the second face sheet. A primary bondline may be coupled to the face sheet(s) and the splice. Further, systems, methods, and apparatus of the present disclosure advantageously reduce the load, provide a redundant path, reduce structural fatigue, and/or increase fatigue life.

  17. Cherenkov radiation of a Josephson vortex moving in a sandwich embedded in a dielectric medium

    SciTech Connect

    Malishevskii, A. S., E-mail: malish@lebedev.ru; Silin, V. P.; Uryupin, S. A.; Uspenskii, S. G. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2008-08-15

    A motion of a Josephson vortex in a long sandwich embedded in a dielectric medium is described. If the velocity of the vortex is greater than the velocity of light in the dielectric, terahertz-band Cherenkov radiation is generated and emitted from the lateral surface of the sandwich. The radiation loss power is determined. In the case when radiation loss is compensated for by the energy gain due to transport current, a relation between the current and the velocity of the vortex is obtained.

  18. On core compressibility of sandwich composite panels subjected to intense underwater shock loads

    NASA Astrophysics Data System (ADS)

    Ghoshal, Ritwik; Mitra, Nilanjan

    2014-01-01

    Novel analytical models have been proposed in this study which extends current available fluid-structure interaction (FSI) theories for explosion induced shock loading on monolithic and laminated composite plates to sandwich composite panels, featuring core compression. The proposed models have been asymptotically validated against other FSI existing theories in low pressure range. A qualitative comparative analysis of the proposed models has been made with other existing FSI theories from the viewpoint of energy conservation. Core compression as predicted by the proposed models can be utilized for more economical, robust design of blast resistant sandwich composite structures.

  19. Behaviour of cellular foam core materials in GRP sandwich under fatigue

    SciTech Connect

    Aamlid, O.; Echtermeyer, A.T.; McGeorge, D.; Buene, L. [Det Norske Veritas Research AS, Hoevik (Norway)

    1993-12-31

    This paper concerns four point bend testing of sandwich beams with PVC foam cores, representative of hull panels in high speed light craft. The study focuses on the long term behavior of cellular foam core materials when the sandwich beam is subjected to fatigue loading until the specimen fails due to shear fracture or excessive shear deformations in the core. The core materials tested include the partially cross-linked PVC Divinycell H100 and H200 and the linear PVC Airex R63.80. Results from the program are presented and discussed.

  20. Impact damage detection in composite chiral sandwich panels using nonlinear vibro-acoustic modulations

    NASA Astrophysics Data System (ADS)

    Klepka, Andrzej; Staszewski, Wieslaw J.; di Maio, Dario; Scarpa, Fabrizio

    2013-08-01

    This paper reports an application of nonlinear acoustics to impact damage detection in a composite chiral sandwich panel. The panel is built from a chiral honeycomb and two composite skins. High-frequency ultrasonic excitation and low-frequency modal excitation were used to observe nonlinear modulations in ultrasonic waves due to structural damage. Low-profile, surface-bonded piezoceramic transducers were used for ultrasonic excitation. Non-contact laser vibrometry was applied for ultrasonic sensing. The work presented focuses on the analysis of the modulation intensities and damage-related nonlinearities. The paper demonstrates that the method can be used for impact damage detection in composite chiral sandwich panels.

  1. Analyses for Debonding of Stitched Composite Sandwich Structures Using Improved Constitutive Models

    NASA Technical Reports Server (NTRS)

    Glaessgen, E. H.; Sleight, D. W.; Krishnamurthy, T.; Raju, I. S.

    2001-01-01

    A fracture mechanics analysis based on strain energy release rates is used to study the effect of stitching in bonded sandwich beam configurations. Finite elements are used to model the configurations. The stitches were modeled as discrete nonlinear spring elements with a compliance determined by experiment. The constitutive models were developed using the results of flatwise tension tests from sandwich material rather than monolithic material. The analyses show that increasing stitch stiffness, stitch density and debond length decrease strain energy release rates for a fixed applied load.

  2. A {3,2}-Order Bending Theory for Laminated Composite and Sandwich Beams

    NASA Technical Reports Server (NTRS)

    Cook, Geoffrey M.; Tessler, Alexander

    1998-01-01

    A higher-order bending theory is derived for laminated composite and sandwich beams thus extending the recent {1,2}-order theory to include third-order axial effect without introducing additional kinematic variables. The present theory is of order {3,2} and includes both transverse shear and transverse normal deformations. A closed-form solution to the cylindrical bending problem is derived and compared with the corresponding exact elasticity solution. The numerical comparisons are focused on the most challenging material systems and beam aspect ratios which include moderate-to-thick unsymmetric composite and sandwich laminates. Advantages and limitations of the theory are discussed.

  3. FaceSheet Push-off Tests to Determine Composite Sandwich Toughness at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Gates, Thomas S.; Herring, Helen M.

    2001-01-01

    A new novel test method, associated analysis, and experimental procedures are developed to investigate the toughness of the facesheet-to-core interface of a sandwich material at cryogenic temperatures. The test method is designed to simulate the failure mode associated with facesheet debonding from high levels of gas pressure in the sandwich core. The effects of specimen orientation are considered, and the results of toughness measurements are presented. Comparisons are made between room and liquid nitrogen (-196 C) test temperatures. It was determined that the test method is insensitive to specimen facesheet orientation and strain energy release rate increases with a decrease in the test temperature.

  4. Parameter Estimation in Hybrid Active-Passive Laminated Sandwich Composite Structures

    SciTech Connect

    Araujo, A. L. [ESTIG-Polytechnic Institute of Braganca, Campus de Sta. Apolonia, Apartado 1134, 5301-857 Braganca (Portugal); Mota Soares, C. M.; Mota Soares, C. A. [IDMEC/IST-Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Herskovits, J. [COPPE/UFRJ-Federal University of Rio de Janeiro, Caixa Postal 68503, 21945-970 Rio de Janeiro (Brazil)

    2010-05-21

    In this article we present recent developments regarding parameter estimation in sandwich structures with viscoelastic frequency dependent core and elastic laminated skin layers, with piezoelectric patch sensors and actuators bonded to the exterior surfaces of the sandwich. The frequency dependent viscoelastic properties of the core material are modelled using fractional derivative models, with unknown parameters that are to be estimated by an inverse technique, using experimentally measured natural frequencies and associated modal loss factors. The inverse problem is formulated as a constrained minimization problem, and gradient based optimization techniques are employed. An application case is presented and discussed, focused on identification of viscoelastic frequency dependent core material properties.

  5. Modeling and Identification of Nonlinear Cascade and Sandwich Systems with General Backlash

    NASA Astrophysics Data System (ADS)

    Vrs, Jozef

    2014-03-01

    The paper deals with modeling and identification of nonlinear cascade and sandwich systems including general backlash, where instead of the straight lines determining the upward and downward parts of backlash characteristic, general curves are considered. This enables more precise modeling of mechanical parts and improves the performance of control systems. The analytical description of the general backlash leads to mathematical models of the cascade system with output general backlash and the sandwich system with internal general backlash, where all the model parameters are separated. Hence, the identification is solved as a quasi-linear problem. Iterative algorithms with internal variables estimation are proposed and illustrative examples are included.

  6. Transition metal sandwich molecules with large (C n, n ? 24) zigzag poly aromatic hydrocarbons

    NASA Astrophysics Data System (ADS)

    Philpott, Michael R.; Kawazoe, Yoshiyuki

    2008-06-01

    Ab initio plane wave based density functional theory was used to study the electronic structure and geometry of sandwich structures M nR 2 consisting of a layer of palladium metal atoms between large eclipsed pericondensed aromatic hydrocarbon molecules: ovalene C 32H 14, circumanthracene C 40H 16, circumpyrene C 42H 16 and circumcoronene C 54H 18. The analysis was guided by the results from the smaller sandwiches: Pd(C 6H 6) 2, symmetric isomers of Pd 2(C 16H 10) 2, Pd 4(C 16H 10) 2, Pd 6(C 24H 12) 2 and Pd 7(C 24H 12) 2 comprised of benzene, pyrene and coronene, which represented the different types of metal binding sites and their combinations found in the larger systems. Isometric surfaces of the total electronic charge density were used to interpret the bonding and coordination of metal atoms and were especially useful when their sites lacked symmetry. Starting from an initial geometry where each metal was assigned to each eclipsed pair of rings, geometry optimization showed that there was a preference for the metal atoms to coordinate to carbon atoms on the circumference of the sandwich where the C-C bond charge density in the isolated hydrocarbon was highest. This resulted in many nearest metal-metal atom distances greater than that in the bulk metal and a frustration of the formation of metal clusters with direct metal-metal bonds. In the two largest sandwiches with circumpyrene and circumcoronene, the perimeter-to-area ratio was reduced enough so that the total frustration was lifted and small core metal arrays were established in the central region. In the circumpyrene sandwich, the four metal core atoms had M-M bonds and some M-C bonds which held the sandwich flat. In contrast, the circumcoronene sandwich displayed a distinctive central bulge around a seven atom M-M bonded core. This study showed that interior metal bonding can have considerable variability over that previously reported and it provided confirmation for M-C edge bond sites with ?2- and ?3-coordination that were previously identified in small sandwich systems.

  7. Using Conducting Wire at A-Sandwich Junctions to Improve the Transmission Performance of Radomes

    NASA Astrophysics Data System (ADS)

    Inasawa, Yoshio; Nishimura, Toshio; Tsuruta, Jun; Miyashita, Hiroaki; Konishi, Yoshihiko

    We present design procedures for using conducting wires in A-sandwich junctions to achieve high transmission performance; benchtest results validate the procedures. The scattering characteristics of the junction are obtained by solving the electric field integral equation of volumetric equivalent currents. The transmission performance is evaluated by subtracting the scattered fields of the same-sized A-sandwich panel in order to offset the effect of edge diffraction. Optimum wire width is determined by examining transmission performance with different arrangements. The designed junction achieves high transmission performance. The measured scattering characteristics of a bench model demonstrate the validity of the presented method.

  8. Migration patterns and moult of Common Terns Sterna hirundo and Sandwich Terns Sterna sandvicensis using Teesmouth in late summer

    Microsoft Academic Search

    Robin M. Ward

    2000-01-01

    Count, recovery and biometric data were analysed to assess the conservation status and use of Teesmouth by Common Terns Sterna hirundo and Sandwich Terns Sterna sandvicensis in late summer. The recognition of the international importance of Teesmouth to migratory Sandwich Terns was endorsed. Peak late summer counts for 19901997 averaged 1,835, over 1% of the international population. Analysis of information

  9. Wet-sand impulse loading of metallic plates and corrugated core sandwich panels J.J. Rimoli a

    E-print Network

    Wadley, Haydn

    Wet-sand impulse loading of metallic plates and corrugated core sandwich panels J.J. Rimoli a , B the mechanical response of edge-clamped sandwich panels subject to the impact of explosively driven wet sand of wet sand placed at different standoff distances. Monolithic plates of the same alloy and mass per unit

  10. Response of composite sandwich panels with transversely flexible core to low-velocity transverse impact: A new dynamic model

    Microsoft Academic Search

    K. Malekzadeh; M. R. Khalili; R. K. Mittal

    2007-01-01

    A new computational procedure based on improved higher order sandwich plate theory (IHSAPT) and two models representing contact behavior between the impactor and the panel are adopted to study the low velocity impact phenomenon of sandwich panels comprising of a transversely flexible core and laminated composite face-sheets. The interaction between the impactor and the panel is modeled with the help

  11. Viscoelastic Analysis of Sandwich Beams Having Aluminum and Fiber-reinforced Polymer Skins with a Polystyrene Foam Core

    E-print Network

    Roberts-Tompkins, Altramese L.

    2010-07-14

    of the sandwich beam with aluminum of FRP as the skin material ............................................................................................... 55 3.15. Comparison of the shear strain field at a distance of 83.3 mm from the midspan... of the sandwich beam with aluminum of FRP as the skin material ....................................................................................................... 58 3.16. Comparison of the transverse strain field at a distance of 83.3 mm from...

  12. Geometrically exact sandwich shells: The dynamic case L. Vu-Quoc *, H. Deng, X.G. Tan

    E-print Network

    Vu-Quoc, Loc

    Geometrically exact sandwich shells: The dynamic case L. Vu-Quoc *, H. Deng, X.G. Tan Department geometrically exact multilayer shell model developed earlier. The dynamics of the motion of sandwich shells be arbitrary, thus make it suitable to model shell structures with patches of constrained viscoelastic

  13. Geometrically-exact sandwich shells: The static case L. Vu-Quoc *, H. Deng, X.G. Tan

    E-print Network

    Vu-Quoc, Loc

    Geometrically-exact sandwich shells: The static case L. Vu-Quoc *, H. Deng, X.G. Tan Department of geometrically-exact sandwich shells undergoing large deformation. The layer directors at a point to model shell structures with patches of constrained vi- scoelastic materials or of piezoelectric

  14. Construction crane

    NSDL National Science Digital Library

    N/A N/A (None; )

    2007-07-25

    People who operate construction cranes carrying heavy loads must be coordinated. The load on the crane must not injure any workers or anyone else near the site. They must be careful to maneuver heavy loads around buildings without hitting them.

  15. Constructing Phylogenies.

    ERIC Educational Resources Information Center

    Bilardello, Nicholas; Valdes, Linda

    1998-01-01

    Introduces a method for constructing phylogenies using molecular traits and elementary graph theory. Discusses analyzing molecular data and using weighted graphs, minimum-weight spanning trees, and rooted cube phylogenies to display the data. (DDR)

  16. Characteristics of Indium-Tin-Oxide\\/Silver\\/Indium-Tin-Oxide Sandwich Films and Their Application to Simple-Matrix Liquid-Crystal Displays

    Microsoft Academic Search

    Masato Sawada; Masatoshi Higuchi; Susumu Kondo; Hiroyasu Saka

    2001-01-01

    We developed low-resistivity transparent conductive films having the structure of indium-tin-oxide\\/silver\\/indium-tin-oxide (ITO\\/Ag\\/ITO). The thin silver film was sandwiched by ITO films. Our goal was to study the characteristics of the sandwich films and the display characteristics of simple-matrix liquid-crystal displays (LCDs) fabricated using the sandwich film. The electrical and optical characteristics of the sandwich films depended greatly on the thickness

  17. Design of metallic textile core sandwich panels F.W. Zok *, H.J. Rathbun, Z. Wei, A.G. Evans

    E-print Network

    Zok, Frank

    Design of metallic textile core sandwich panels F.W. Zok *, H.J. Rathbun, Z. Wei, A.G. Evans-5050, USA Received 3 March 2003 Abstract Metallic sandwich panels with textile cores have been analyzed. All rights reserved. Keywords: Sandwich panels; Lightweight structures; Textiles; Optimal design 1

  18. Thermomechanical vibration of FGM sandwich beam under variable elastic foundations using differential quadrature method

    Microsoft Academic Search

    S. C. Pradhan; T. Murmu

    2009-01-01

    Thermo-mechanical vibration analysis of functionally graded (FG) beams and functionally graded sandwich (FGSW) beams are presented. The functionally graded material (FGM) beams are considered to be resting on variable (i) Winkler foundation and (ii) two-parameter elastic foundation. The material properties of these beams are assumed to be varying in the thickness direction. The governing differential equations for beam vibration are

  19. Postbuckling of sandwich plates with FGM face sheets and temperature-dependent properties

    Microsoft Academic Search

    Hui-Shen Shen; Shi-Rong Li

    2008-01-01

    Compressive postbuckling under thermal environments and thermal postbuckling due to heat conduction are presented for a simply supported, sandwich plate with FGM face sheets. The material properties of FGM face sheets are assumed to be graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of the constituents, and the material properties

  20. The Sandwich Mom: In the Throes of a Medication Safety Perfect Storm

    Microsoft Academic Search

    Dennis H. Tootelian; Michael Negrete; John T. Skhal

    2010-01-01

    America is entering into a proverbial perfect storm of medication errors. Medications are more complex and their use is increasing, consumers are more involved in their healthcare decisions, and the population is aging and with it comes diminished cognitive skills. Sandwich moms are likely to bear the brunt of the ravages of this storm. These are the women who serve

  1. Ultra-Lightweight Nanocomposite Foams and Sandwich Structures for Space Structure Applications

    NASA Technical Reports Server (NTRS)

    Tan, Seng

    2012-01-01

    Microcellular nanocomposite foams and sandwich structures have been created to have excellent electrical conductivity and radiation-resistant properties using a new method that does not involve or release any toxicity. The nanocomposite structures have been scaled up in size to 12 X 12 in. (30 X 30 cm) for components fabrication. These sandwich materials were fabricated mainly from PE, CNF, and carbon fibers. Test results indicate that they have very good compression and compression-after-impact properties, excellent electrical conductivity, and superior space environment durability. Compression tests show that 1000 ESH (equivalent Sun hours) of UV exposure has no effect on the structural properties of the sandwich structures. The structures are considerably lighter than aluminum alloy (= 36 percent lighter), which translates to 36 percent weight savings of the electronic enclosure and its housing. The good mechanical properties of the materials may enable the electronic housing to be fabricated with a thinner structure that further reduces the weight. There was no difficulty in machining the sandwich specimens into electronic enclosure housing.

  2. On stress concentration in the bending of sandwich beams with transversely flexible core

    Microsoft Academic Search

    Y. Frostig

    1993-01-01

    Stress concentrations in sandwich beams with compressible cores, subjected to bending loading are investigated, and the level of stress concentrations under ordinary bending loads in various regions of the structure, and under some common-practice conditions, is analytically determined. The cases investigated include stress concentration effects for the following conditions: (1) in the vicinity of concentrated loads and supporting zones, (2)

  3. A SERS-based sandwich assay for ultrasensitive and selective detection of Alzheimer's tau protein.

    PubMed

    Zengin, Adem; Tamer, Ugur; Caykara, Tuncer

    2013-09-01

    In this study, a simple and highly selective homogeneous sandwich assay was developed for fast and ultrasensitive detection of the tau protein using a combination of monoclonal antitau functionalized hybrid magnetic nanoparticles and polyclonal antitau immobilized gold nanoparticles as the recognition and surface-enhanced Raman scattering (SERS) component, respectively. The magnetic silica particles were first coated with poly(2-hydroxyethyl methacrylate) via surface-mediated reversible addition-fragmentation chain transfer (RAFT) polymerization and then biofunctionalized with monoclonal antitau, which are both specific for tau and can be collected via a simple magnet. After separating tau from the sample matrix, they were sandwiched with the SERS substrate composed of polyclonal antitau and 5,5-dithiobis(2-dinitrobenzoic acid) on gold nanoparticles. The correlation between the tau concentration and SERS signal was found to be linear within the range of 25 fM to 500 nM. The limit of detection for the sandwich assay is less than 25 fM. Moreover, the sandwich assay was also evaluated for investigating the tau specificity on bovine serum albumin and immunoglobulin G. PMID:23885927

  4. STS-43 Pilot Baker eats a sandwich on OV-104's forward flight deck

    NASA Technical Reports Server (NTRS)

    1991-01-01

    STS-43 Pilot Michael A. Baker, seated at the forward flight deck pilots station controls, eats a freefloating peanut butter and jelly sandwich while holding a carrot. Surrounding Baker on Atlantis', Orbiter Vehicle (OV) 104's, flight deck are procedural checklists, control panels, and windows. A lemonade drink bag is velcroed to overhead panel O9.

  5. The forced vibration of a three-layer, damped sandwich beam with arbitrary boundary conditions

    Microsoft Academic Search

    D. J. Mead; S. Markus

    1969-01-01

    The sixth-order differential equation of motion is derived in terms of the transverse displacement, w, for a three-layer sandwich beam with a viscoelastic core. Mathematical expressions in terms of w are found for a variety of beam boundary conditions. The solution of the differential equation by the method of Di Taranto is shown to yield a special class of complex,

  6. An analytical and experimental investigation of sandwich composites subjected to low-velocity impact

    NASA Astrophysics Data System (ADS)

    Anderson, Todd Alan

    1999-12-01

    This study involves an experimental and analytical investigation of low-velocity impact phenomenon in sandwich composite structures. The analytical solution of a three-dimensional finite-geometry multi-layer specially orthotropic panel subjected to static and transient transverse loading cases is presented. The governing equations of the static and dynamic formulations are derived from Reissner's functional and solved by enforcing the continuity of traction and displacement components between adjacent layers. For the dynamic loading case, the governing equations are solved by applying Fourier or Laplace transformation in time. Additionally, the static solution is extended to solve the contact problem between the sandwich laminate and a rigid sphere. An iterative method is employed to determine the sphere's unknown contact area and pressure distribution. A failure criterion is then applied to the sandwich laminate's stress and strain field to predict impact damage. The analytical accuracy of the present study is verified through comparisons with finite element models, other analyses, and through experimentation. Low-velocity impact tests were conducted to characterize the type and extent of the damage observed in a variety of sandwich configurations with graphite/epoxy face sheets and foam or honeycomb cores. Correlation of the residual indentation and cross-sectional views of the impacted specimens provides a criterion for the extent of damage. Quasi-static indentation tests are also performed and show excellent agreement when compared with the analytical predictions. Finally, piezoelectric polyvinylidene fluoride (PVF2) film sensors are found to be effective in detecting low-velocity impact.

  7. Low-velocity heavy-mass impact response of slender metal foam core sandwich beam

    Microsoft Academic Search

    Qing Hua Qin; T. J. Wang

    2011-01-01

    The objective of this work is to investigate the dynamic large deflection response of fully clamped metal foam core sandwich beam struck by a low-velocity heavy mass. Analytical solution and bounds of dynamic solutions are derived, respectively. Also, finite element analysis is carried out to obtain the numerical solution of the problem. Comparisons of the dynamic, the quasi-static and numerical

  8. Finite element modelling of low velocity impact of composite sandwich panels

    Microsoft Academic Search

    T Besant; G. A. O Davies; D Hitchings

    2001-01-01

    This paper outlines a finite element procedure for predicting the behaviour under low velocity impact of sandwich panels consisting of brittle composite skins supported by a ductile core. The modelling of the impact requires a dynamic analysis that can also handle non-linearities caused by large deflections, plastic deformation of the core and in-plane degradation of the composite skins. Metal honeycomb,

  9. Sandwiches come with the following: Mayo or mustard, lettuce, tomatoes, red onions, pickles, pepperoncinis, salt & pepper.

    E-print Network

    de Lijser, Peter

    COLD TOGO'S WAY Sandwiches come with the following: Mayo or mustard, lettuce, tomatoes, red onions & SWEETS SALADS & SALAD WRAPS FAVORITES BBQ Ranch Chicken - Chicken, BBQ sauce, red onions, tomatoes, carrots, red cabbage, wontons and sesame seeds, lettuce, green onions and Italian parsley, Asian dressing

  10. A protocol for characterizing the structural performance of metallic sandwich panels: application to pyramidal

    E-print Network

    Zok, Frank

    to pyramidal truss cores F.W. Zok *, S.A. Waltner, Z. Wei, H.J. Rathbun, R.M. McMeeking, A.G. Evans Materials of realizing this objective is presented and demonstrated for panels with pyramidal truss cores. It combines; Pyramidal core; Constitutive law; Clamped bending; Three-point bending 1. Introduction Metallic sandwich

  11. Bending behavior of lightweight sandwich-walled shells with pyramidal truss cores

    E-print Network

    Vaziri, Ashkan

    Bending behavior of lightweight sandwich-walled shells with pyramidal truss cores J. Xiong a , R s t r a c t A study on the bending response of a composite curved panel with pyramidal metallic truss, three-point bending experiments and finite element (FE) based simulations. The aluminum pyramidal cores

  12. Shear and bending performance of carbon fiber composite sandwich panels with pyramidal truss cores

    E-print Network

    Vaziri, Ashkan

    Shear and bending performance of carbon fiber composite sandwich panels with pyramidal truss cores presented for possible competing fail- ure modes. In the experimental part of the study, pyramidal truss: Composites; Pyramidal truss cores; Shear; Bending; Failure mechanisms 1. Introduction Fiber reinforced

  13. Optimum stacking sequence design of composite sandwich panel using genetic algorithms

    NASA Astrophysics Data System (ADS)

    Bir, Amarpreet Singh

    Composite sandwich structures recently gained preference for various structural components over conventional metals and simple composite laminates in the aerospace industries. For most widely used composite sandwich structures, the optimization problems only requires the determination of the best stacking sequence and the number of laminae with different fiber orientations. Genetic algorithm optimization technique based on Darwin's theory of survival of the fittest and evolution is most suitable for solving such optimization problems. The present research work focuses on the stacking sequence optimization of composite sandwich panels with laminated face-sheets for both critical buckling load maximization and thickness minimization problems, subjected to bi-axial compressive loading. In the previous studies, only balanced and even-numbered simple composite laminate panels have been investigated ignoring the effects of bending-twisting coupling terms. The current work broadens the application of genetic algorithms to more complex composite sandwich panels with balanced, unbalanced, even and odd-numbered face-sheet laminates including the effects of bending-twisting coupling terms.

  14. Vacuum Bag Only Prepreg Processing of Honeycomb Sandwich Panels James Kratz

    E-print Network

    Dawson, Jeff W.

    Vacuum Bag Only Prepreg Processing of Honeycomb Sandwich Panels James Kratz Department that consistently produce predictable results are needed. Vacuum-bag-only (VBO) manufacturing is one possible solution that relies on vacuum to remove all entrapped volatiles prior to cure, and then the differential

  15. Enhanced thermal stability of functionally graded sandwich cylindrical shells by shape memory alloys

    NASA Astrophysics Data System (ADS)

    Asadi, H.; Akbarzadeh, A. H.; Chen, Z. T.; Aghdam, M. M.

    2015-04-01

    The present paper deals with the nonlinear thermal instability of geometrically imperfect sandwich cylindrical shells under uniform heating. The sandwich shells are made of a shape memory alloy (SMA)-fiber-reinforced composite and functionally graded (FG) face sheets (FG/SMA/FG). The Brinson phenomenological model is used to express the constitutive characteristics of SMA fibers. The governing equations are established within the framework of the third-order shear deformation shell theory by taking into account the von Karman geometrical nonlinearity and initial imperfection. The material properties of constituents are assumed to be temperature dependent. The Galerkin technique is utilized to derive expressions of the bifurcation points and bifurcation paths of the sandwich cylindrical shells. Using the developed closed-form solutions, extensive numerical results are presented to provide an insight into the influence of the SMA fiber volume fraction, SMA pre-strain, core thickness, non-homogeneity index, geometrical imperfection, geometry parameters of sandwich shells and temperature dependency of materials on the stability of shells. The results reveal that proper application of SMA fibers postpones the thermal bifurcation point and dramatically decreases thermal post-buckling deflection. Moreover, the induced tensile recovery stress of SMA fibers could also stabilize the geometrically imperfect shells during the inverse martensite phase transformation.

  16. Non-linear finite element analysis of inserts in composite sandwich structures

    Microsoft Academic Search

    P. Bunyawanichakul; B. Castani; J.-J. Barrau

    2008-01-01

    In aeronautics, sandwich structures are widely used for secondary structures like flaps, landing gear doors or commercial equipment. The technologies used to join these kinds of structures are numerous: direct bonding or joining, tapered areas, T-joints, etc. The most common is certainly the use of local reinforcement called an insert. The insert technologies are numerous and this study focuses on

  17. Use of GFRP Grid for Innovative Concrete Sandwich Panels Jonathan G. Soriano1

    E-print Network

    as a shear transfer mechanism for concrete sandwich wall panels typically used for a building envelope. These wall panels are typically prestressed and can be used in structural or architectural applications structures and bridges. Recently, GFRP has been introduced as a new alternative reinforcement for cast

  18. Sandwich Student: Business, Skills and Marketing Coordinator (IRC22448) Salary: 16,765 per annum

    E-print Network

    Sandwich Student: Business, Skills and Marketing Coordinator (IRC22448) Salary: £16,765 per annum Recruitment Portal where you can complete an online application form. To find this vacancy type `Business and implementation of various marketing plans, by identifying key partners and customers and proposals for contacting

  19. Effect of debonding damage on the modal damping of a sandwich panel

    Microsoft Academic Search

    I. Peroni; A. Paolozzi; A. Bramante

    1991-01-01

    The objective of the present work is to study the effect of debonding damage on the modal damping of a sandwich panel. The experimental FRF, obtained with a broadband excitation, were already available from an analogous research concerning the variations of resonant frequencies. For some modes the results have shown that increases in severity of damage cause a slight increase

  20. A Novel SERRS Sandwich-Hybridization Assay to Detect Specific DNA Target

    Microsoft Academic Search

    Ccile Feuillie; Maxime Mohamad Merheb; Benjamin Gillet; Gilles Montagnac; Isabelle Daniel; Catherine Hnni; Vladimir N. Uversky

    2011-01-01

    In this study, we have applied Surface Enhanced Resonance Raman Scattering (SERRS) technology to the specific detection of DNA. We present an innovative SERRS sandwich-hybridization assay that allows specific DNA detection without any enzymatic amplification, such as is the case with Polymerase Chain Reaction (PCR). In some substrates, such as ancient or processed remains, enzymatic amplification fails due to DNA

  1. The Association between Membership in the Sandwich Generation and Health Behaviors: A Longitudinal Study

    ERIC Educational Resources Information Center

    Chassin, Laurie; Macy, Jon T.; Seo, Dong-Chul; Presson, Clark C.; Sherman, Steven J.

    2010-01-01

    The current study examined the association between membership in the sandwich generation, defined as providing care to both children and parents or in-laws, and five health behaviors: checking the food label for health value when buying foods, using a seat belt, choosing foods based on health value, exercising regularly, and cigarette smoking.

  2. The effects of in-plane core stiffness on the wrinkling behavior of thick sandwiches

    Microsoft Academic Search

    W. K. Vonach; F. G. Rammerstorfer

    2000-01-01

    Summary This contribution presents a refined analytical solution for the wrinkling of sandwich plates with isotropic face layers and thick orthotropic cores, taking into accountin-plane deformations of the core. A single explicit equation for the critical wrinkling load in an asymptotic sense in derived. The results have been verified extensively by a numerical model [1] and show that, when dealing

  3. Temperature effects on Kevlar\\/hybrid and carbon fiber composite sandwiches under impact loading

    Microsoft Academic Search

    Amin Salehi-Khojin; Mohammad Mahinfalah; Reza Bashirzadeh; Brian Freeman

    2007-01-01

    This paper presents the results of a research on impacted sandwich composites with Kevlar\\/hybrid and carbon facesheets subjected to different temperatures. Testing was performed to determine bending and core shear stresses, maximum energy absorption, and absorbing energy and moment parameter (AEMP), performance parameter (PP), and compression strength after impact (CSAI). Specimens were tested at temperature range of ?50C to 120C

  4. Comparison of Retention Rates Using Traditional, Drill Sandwich, and Incremental Rehearsal Flash Card Methods.

    ERIC Educational Resources Information Center

    MacQuarrie, Lara L.; Tucker, James A.; Burns, Matthew K.; Hartman, Brian

    2002-01-01

    Research has demonstrated increased retention from drill, but the data regarding drill format are inconsistent. Two commonly used models, Drill Sandwich (DS) and Incremental Rehearsal (IR), were compared to each other and to a traditional flashcard method. The IR model consistently led to significantly more words retained than the traditional or

  5. Closure of multiple ventricular septal defects by the felt sandwich technique: Further analysis of 36 patients

    Microsoft Academic Search

    Hirohisa Murakami; Naoki Yoshimura; Hiroaki Takahashi; Hironori Matsuhisa; Masahiro Yoshida; Yoshihiro Oshima; Takuro Misaki; Masahiro Yamaguchi

    2010-01-01

    Results: Sixty-three trabecular ventricular septal defects in 36 patients were closed with the felt sandwich technique. In the early postoperative period, 1 patient died of pulmonary hypertensive crisis. There were 2 late deaths. One patient died of pneumonia 6 months after surgery, and another died suddenly of ventricular ar- rhythmias 2 years after surgery. Three patients required reoperation (closure of

  6. Job Burnout and Couple Burnout in Dual-Earner Couples in the Sandwiched Generation

    ERIC Educational Resources Information Center

    Pines, Ayala Malach; Neal, Margaret B.; Hammer, Leslie B.; Icekson, Tamar

    2011-01-01

    We use existential theory as a framework to explore the levels of and relationship between job and couple burnout reported by dual-earner couples in the "sandwich generation" (i.e., couples caring both for children and aging parents) in a sample of such couples in Israel and the United States. This comparison enables an examination of the

  7. Effect of core topology on projectile penetration in hybrid aluminum/alumina sandwich structuresq

    E-print Network

    Wadley, Haydn

    Effect of core topology on projectile penetration in hybrid aluminum/alumina sandwich structuresq H sectioning of impacted samples was used to investigate the penetra- tion mechanisms. We find in water [3e6] and to a lesser extent in air [7e10] or by soil impact [11e14]. Recent studies [15

  8. Modelling of low-energy\\/low-velocity impact on Nomex honeycomb sandwich structures with metallic skins

    Microsoft Academic Search

    B. Castani; C. Bouveta; Y. Aminanda; J.-J. Barrau; P. Thevenet

    2008-01-01

    In the aircraft industry, manufacturers have to decide quickly whether an impacted sandwich needs repairing or not. Certain computation tools exist at present but they are very time-consuming and they also fail to perfectly model the physical phenomena involved in an impact. In a previous publication, the authors demonstrated the possibility of representing the Nomex honeycomb core by a grid

  9. UN MODELLO ANALITICO PER IMPATTO A BASSA VELOCITA' SU PANNELLI SANDWICH (Al-Nomex)

    Microsoft Academic Search

    M. Giglioa

    Starting from a previous work about low velocity impact tests on sandwich panels, a larger research activity on the same topic is presented, including experimental tests and an analytical model. In particular a partial original model to obtain the impact key parameters is explained with particular consideration on the mechanical characteristic of the materials; the properties of honeycomb core are

  10. Evaluation of modal-based damage detection techniques for composite aircraft sandwich structures

    Microsoft Academic Search

    J. A. Oliver; J. B. Kosmatka

    2005-01-01

    Composite sandwich structures are important as structural components in modern lightweight aircraft, but are susceptible to catastrophic failure without obvious forewarning. Internal damage, such as disbonding between skin and core, is detrimental to the structures' strength and integrity and thus must be detected before reaching critical levels. However, highly directional low density cores, such as Nomex honeycomb, make the task

  11. Damage Detection and Impact Testing on Laminated and Sandwich Composite Panels

    NASA Technical Reports Server (NTRS)

    Hughes, Derke R.; Craft, William J.; Schulz, Mark J.; Naser, Ahmad S.; Martin, William N.

    1998-01-01

    This research investigates health monitoring of sandwich shell composites to determine if the Transmittance Functions (TF) are effective in determining the present of damage. The health monitoring test was conducted on the sandwich plates before and after low velocity impacts using the health monitoring technique given in TFs are a NDE (Nondestructive Evaluation) technique that utilizes the ratios of cross-spectrums to auto-spectrums between two response points on the sandwich composites. The test for transmittance was conducted on the same density foam core throughout the experiment. The test specimens were 17.8 cm by 25.4 cm in dimension. The external sheets (face sheets) were created from graphite/epoxy laminate with dimension of 1.58 mm thick. The polymethacrylide (Rohacell) foam core was 12.7 mm thick. These samples experienced a transformation in the TF that was considered the low velocity impact damage. The low velocity damage was observed in the TFs for the sandwich composites.

  12. Experimental investigation of graphite/polyimide sandwich panels in edgewise compression. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Camarda, C. J.

    1980-01-01

    The local and general buckling of graphite/polyimide sandwich panels simply supported along all four edges and loaded in uniaxial edgewise compression is investigated. Material properties of sandwich panel constituents (adhesive and facings) were determined from flatwise tension and sandwich beam flexure tests. An adhesive bond study resulted in the selection of a suitable cure cycle for FM 34 polyimide film adhesive and, a bonding technique using a liquid cell edge version of that adhesive resulted in considerable mass savings. Tensile and compressive material properties of the facings, quasiisotropic, symmetric, laminates (0, +45,90,-45)s of Celion/PMR-15, were determined at 116, R.T., and 589 K (-250, R.T., and 600 F) usng the sandwich beam flexure test method. Results indicate the Gr/PI is a usable structural material for short term use at temperatures as high as 589 K (600 F). Buckling specimens were 1006.5 sq cm. 156 sq in., had quasiisotropic symmetric facings (0, + or - 45,90)s and a glass/polyimide honeycomb core (HRH-327-3/8-4).

  13. Experimental characterization and numerical simulations of a syntactic-foam/glass-bre composite sandwich

    E-print Network

    Corigliano, Alberto

    core. Such core consists of a syntactic foam made by hollow glass microspheres embedded in an epoxy). The sandwich core material is a syntactic foam consisting of hollow glass microspheres embedded in an epoxyExperimental characterization and numerical simulations of a syntactic-foam/glass-®bre composite

  14. Influence of Filling Medium of Holes on the Negative-Index Response of Sandwiched Metamaterials

    Microsoft Academic Search

    Xu-Dong Wang; Yong-Hong Ye; Ji Ma; Mei-Ping Jiang

    2010-01-01

    We numerically study the negative index properties of sandwiched metamaterials, perforated with a square array of circle holes filled with different media. Transmission spectra indicate that the filling medium can effectively change the position of the localized resonant peak, while keeping the position of the other transmission peaks hardly changed. Reflection spectra and retrieved effective impedance verify that an appropriate

  15. Metal Foam Analysis: Improving Sandwich Structure Technology for Engine Fan and Propeller Blades

    NASA Technical Reports Server (NTRS)

    Fedor, Jessica L.

    2004-01-01

    The Life Prediction Branch of the NASA Glenn Research Center is searching for ways to construct aircraft and rotorcraft engine fan and propeller blades that are lighter and less costly. One possible design is to create a sandwich structure composed of two metal faces sheets and a metal foam core. The face sheets would carry the bending loads and the foam core would have to resist the transverse shear loads. Metal foam is ideal because of its low density and energy absorption capabilities, making the structure lighter, yet still stiff. The material chosen for the face sheets and core was 17-4PH stainless steel, which is easy to make and has appealing mechanical properties. This material can be made inexpensively compared to titanium and polymer matrix composites, the two current fan blade alternatives. Initial tests were performed on design models, including vibration and stress analysis. These tests revealed that the design is competitive with existing designs; however, some problems were apparent that must be addressed before it can be implemented in new technology. The foam did not hold up as well as expected under stress. This could be due to a number of issues, but was most likely a result of a large number of pores within the steel that weakened the structure. The brazing between the face sheets and the foam was also identified as a concern. The braze did not hold up well under shear stress causing the foam to break away from the face sheets. My role in this project was to analyze different options for improving the design. I primarily spent my time examining various foam samples, created with different sintering conditions, to see which exhibited the most favorable characteristics for our purpose. Methods of analysis that I employed included examining strut integrity under a microscope, counting the number of cells per inch, measuring the density, testing the microhardness, and testing the strength under compression. Shear testing will also be done to examine the strengths of different types of brazes.

  16. Joint Salvage Using Sandwich Technique for Giant Cell Tumors around Knee.

    PubMed

    Kundu, Zile Singh; Gogna, Paritosh; Singla, Rohit; Sangwan, Sukhbir Singh; Kamboj, Pradeep; Goyal, Shobit

    2015-04-01

    The most common site for giant cell tumors (GCT) is knee, where the tumor characteristically extends right up to the subarticular bone plate. Extensive curettage with preservation of the joint should be done wherever possible. The alternatives for filling the void left after curettage are either bone graft or bone cement. Sandwich technique uses the advantages of both, taking care to prevent damage to articular cartilage. This study was done to evaluate the results of sandwich technique in tumors around the knee joint. It was a prospective study of 26 consecutive patients (15 females and 11 males) with Campanacci grade II and grade III GCT around the knee, which qualified the inclusion criterion and underwent knee reconstruction with sandwich technique, after extended curettage of the tumor. The mean age of the patients at the time of surgery was 32.73??11.30 years (range, 18-62 years), and the mean follow-up was 3.87??1.26 years (range, 6.5-2 years). At final follow-up, the functional evaluation was done using Musculoskeletal Tumor Society (MSTS) score and measuring range of motion around the knee. Three patients had recurrence of tumor; in one case, we were able to salvage the joint and repeat sandwich surgery was performed, and in the other two cases, the joint was breached; therefore, we resorted to resection arthrodesis. At final follow-up, the mean functional arc of motion around the knee and the mean MSTS score in patients without arthrodesis was 123.52??10.21 degrees (range, 100-130 degrees) and 27.04/30, respectively; all patients were able to do their activities of daily living with ease. Sandwich technique is a good reconstruction procedure in GCT around knee joint with good survival rate, minimal complications, and good functional outcome. PMID:24752921

  17. Enhanced antimelanoma activity of methotrexate and zoledronic acid within polymeric sandwiches.

    PubMed

    Schilrreff, Priscila; Cervini, Gabriela; Romero, Eder Lilia; Morilla, Maria Jose

    2014-10-01

    New therapies are urgently needed against melanoma, one of the most aggressive tumors. Melanoma cells are resistant to the antifolate methotrexate (MTX), since MTX is taken up by the folate receptor-? (FR?), sequestered in melanosomes and exported out of the cell. The bisphosphonate zoledronic acid (ZOL) is active in several non-skeletal tumors; however, its antitumoral activity is hampered by its long-term accumulation in bones and low cellular permeability. Recently, we showed that core-shell tecto-dendrimers made of amine-terminated polyamidoamine generation 5 dendrimer (G5) as core and carboxyl-terminated G2.5 dendrimer as shell (G5G2.5) had selective cytotoxicity to melanoma cells. We hypothesized here that the activity of MTX and ZOL on melanoma cells could be enhanced when loaded within G5G2.5. MTX and ZOL were loaded within G5 cores, which were coated by a covalently bound shell of G2.5 dendrimers (drug-sandwiches). 12nm mean diameter and -12mV Z potential drug-sandwiches incorporating 6 and 31 molecules of MTX and ZOL, respectively, per G5G2.5, showed higher cytotoxicity (by MTT and apoptosis/necrosis assays) to melanoma (Sk-Mel-28) cells than free drugs and G5G2.5. Only MTX-sandwich was cytotoxic to Sk-Mel-28 cells and harmless to keratinocytes (HaCaT cells). The intracellular pathway of G5G2.5 was followed using chemical inhibitors of endocytosis. The increased cytotoxicity of MTX-sandwich could be due to its uptake by macropinocytosis instead of by FR?, avoiding MTX exocytosis. The increased cytotoxicity of ZOL-sandwich could be due to an increased intracellular accumulation of ZOL, owed by its endocytic uptake instead of diffusing as free drug. PMID:25016541

  18. Construction Work

    USGS Multimedia Gallery

    Construction work taking place at the Theodore Roosevelt National Park in North Dakota. Funding for the road project at Theodore Roosevelt National Park comes from the $170 million appropriated for the Federal Highway Administration to spend on roads in national parks....

  19. constructing realization

    E-print Network

    Johannes Kepler University Linz SFB \\Numerical and Symbolic Scienti#12;c Computing" A principle for constructing parallel AMG and its realization II Michael Kuhn, Gundolf Haase Johannes Kepler University Linz. Wolfgang, Upper Austria #12; Johannes Kepler University Linz SFB \\Numerical and Symbolic Scienti#12;c

  20. Constructive Interaction.

    ERIC Educational Resources Information Center

    Miyake, Naomi

    To identify conditions that make a conversational interaction constructive--in the sense that the participants can find the way toward the success of what they wanted to accomplish--two situations were examined. In one, a professional researcher explained her data to a statistician. In the other, three groups of two people cooperated with each

  1. Metal Construction

    NASA Technical Reports Server (NTRS)

    Verduzio, Rodolfo

    1922-01-01

    The future development of aerial navigation is closely connected with the condition of obtaining airplanes of great stability and sufficient strength. Different construction materials such as wood, aluminum, iron, and alloys are examined to determine which materials or combination of materials provides a greater coefficient of safety.

  2. Constructing a \\

    Microsoft Academic Search

    David T. Helm; Sandra L. Friedman

    The end of life is inevitable. The ability to control and participate in one's own life-ending scenario is not. Longer lives, heightened awareness of impending death, and various plan- ning strategies permit us to construct an all-things-being-equal plan for controlling our own \\

  3. Constructive Criticism.

    ERIC Educational Resources Information Center

    Lieberfeld, Lawrence

    1982-01-01

    Many crucial questions need to be answered before a college embarks on a construction project and makes a substantial financial commitment. Computer modeling techniques can be used to make even complex project feasibility analyses. Available from Peat, Marwick, Mitchell & Co., 345 Park Avenue, New York, NY 10154. (MSE)

  4. A highly sensitive sandwich ELISA for the determination of glycomacropeptide to detect liquid whey in raw milk.

    PubMed

    Chvez, Norma A; Jauregui, Juan; Palomares, Laura A; Macas, Karla E; Jimnez, Mariela; Salinas, Eva

    2012-03-01

    Milk processing industries and distributors have problems with adulteration of liquid milk by the addition of bovine cheese whey. Recently, the detection of fraudulent manipulation of milk with whey has focused on the identification of glycomacropeptide (GMP). Current non-immunological methods to detect GMP in dairy products are expensive and time-consuming or have low sensitivity. In this study, a novel sandwich enzyme-linked immunosorbent assay (ELISA) for the detection and quantification of whey in raw milk was developed, using a polyclonal rabbit anti-GMP antibody. Calibration curves were constructed by analyzing raw milk standards containing different known concentrations of liquid cheese whey (0.02-20%). The method had a detection limit of 0.047% (v/v) and a quantification limit of 0.14% (v/v). The antibody showed high specificity and no cross-reaction with milk components (other than ?-casein) and was successful in detecting GMP in dairy commercial products. The recovery ratio was between 95.62% and 113.88% for all matrices tested. The intra-assay and interassay coefficients of variation were <6% and <7%, respectively. Finally, it can be stored for 3months in the form of a ready-to-use kit, while maintaining its accuracy and reproducibility. PMID:22662290

  5. Label-Free Quantification of MicroRNAs Using Ligase-Assisted Sandwich Hybridization on a DNA Microarray

    PubMed Central

    Ueno, Taro; Funatsu, Takashi

    2014-01-01

    MicroRNAs (miRNAs) can be used as biomarkers for cancer and other human diseases; therefore, high-throughput and reliable miRNA-quantification methods are required to exploit these markers for diagnostic testing. In this report, we describe the construction of a platform for miRNA-quantification using ligase-assisted sandwich hybridization (LASH) without miRNA-labeling. T4 DNA ligase was used to compensate for the low affinity between miRNAs and two short complementary DNA probes, and it improved the hybridization yield ?50,000 times. The LASH assay enabled synthesized miR-143 to be quantified at concentrations ranging from 30 fM to 30 pM. The LASH assay could also quantify endogenous miR-143 released from cultured cells as well as some miRNAs in total RNAs derived from blood. Furthermore, multi-color detection enabled us to distinguish between the highly homologous miR-141 and miR-200a. This simple label-free quantification technique is an easy-to-use approach that can be applied to disease diagnosis. PMID:24614340

  6. Construction measurements

    SciTech Connect

    Barry, B.A.

    1988-01-01

    This text/reference on construction measurements contains material concerning electronic surveying and remote sensing. New to this edition is coverage of the GPS satellite positioning system, electronic distance measurement (EDM), laser sweep, calculator techniques, radial surveying and tracking, Loran-C, inertial navigation surveying, 3-point resection, computer software, and electronic fieldbooks. It covers the difference of elevation, angle measurements and directions, coordinate surveying and layout, offshore measurements, and random field and office techniques.

  7. Construct It!

    NSDL National Science Digital Library

    VU Bioengineering RET Program, School of Engineering,

    Students use simple household materials, such as PVC piping and compact mirrors, to construct models of laser-based security systems. The protected object (a "mummified troll" or another treasure of your choosing) is placed "on display" in the center of the modeled room and protected by a laser system that utilizes a laser beam reflected off mirrors to trigger a light trip sensor with alarm.

  8. Graduate Studies Construction Engineering

    E-print Network

    Jacobs, Laurence J.

    funded by the National Science Foundation (NSF), Construction Industry Institute (CII), Georgia engineering, building construction, and industrial and systems engineering. SELECTED COURSES · ConstructionGraduate Studies Construction Engineering CONSTRUCTION ENGINEERING The construction engineering

  9. Analysis of an Aircraft Honeycomb Sandwich Panel with Circular Face Sheet/Core Disbond Subjected to Ground-Air Pressurization

    NASA Technical Reports Server (NTRS)

    Rinker, Martin; Krueger, Ronald; Ratcliffe, James

    2013-01-01

    The ground-air pressurization of lightweight honeycomb sandwich structures caused by alternating pressure differences between the enclosed air within the honeycomb core and the ambient environment is a well-known and controllable loading condition of aerospace structures. However, initial face sheet/core disbonds intensify the face sheet peeling effect of the internal pressure load significantly and can decrease the reliability of the sandwich structure drastically. Within this paper, a numerical parameter study was carried out to investigate the criticality of initial disbonds in honeycomb sandwich structures under ground-air pressurization. A fracture mechanics approach was used to evaluate the loading at the disbond front. In this case, the strain energy release rate was computed via the Virtual Crack Closure Technique. Special attention was paid to the pressure-deformation coupling which can decrease the pressure load within the disbonded sandwich section significantly when the structure is highly deformed.

  10. A Finite Element Analysis for Predicting the Residual Compressive Strength of Impact-Damaged Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.; Jackson, Wade C.

    2008-01-01

    A simple analysis method has been developed for predicting the residual compressive strength of impact-damaged sandwich panels. The method is tailored for honeycomb core-based sandwich specimens that exhibit an indentation growth failure mode under axial compressive loading, which is driven largely by the crushing behavior of the core material. The analysis method is in the form of a finite element model, where the impact-damaged facesheet is represented using shell elements and the core material is represented using spring elements, aligned in the thickness direction of the core. The nonlinear crush response of the core material used in the analysis is based on data from flatwise compression tests. A comparison with a previous analysis method and some experimental data shows good agreement with results from this new approach.

  11. A Finite Element Analysis for Predicting the Residual Compression Strength of Impact-Damaged Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.; Jackson, Wade C.

    2008-01-01

    A simple analysis method has been developed for predicting the residual compression strength of impact-damaged sandwich panels. The method is tailored for honeycomb core-based sandwich specimens that exhibit an indentation growth failure mode under axial compression loading, which is driven largely by the crushing behavior of the core material. The analysis method is in the form of a finite element model, where the impact-damaged facesheet is represented using shell elements and the core material is represented using spring elements, aligned in the thickness direction of the core. The nonlinear crush response of the core material used in the analysis is based on data from flatwise compression tests. A comparison with a previous analysis method and some experimental data shows good agreement with results from this new approach.

  12. Development of a smart-skin phased array system with a honeycomb sandwich microstrip antenna

    NASA Astrophysics Data System (ADS)

    Son, Seong Ho; Eom, Soon Young; Hwang, Woonbong

    2008-06-01

    We develop a smart-skin phased array antenna (PAA) with a scanning beam and cover the design, fabrication and testing of the smart-skin antenna structure, the phase shifter and electronic beam scanning. The smart skin is an organic honeycomb sandwich structure in which microstrip antennas are embedded that radiate a radio-frequency (RF) signal. The structure has excellent structural performance as a result of sandwich effects by facesheets and a honeycomb core. For ease of array feeding, the antenna element is excited by means of a coaxial probe. A stacked patch is used in order to increase the bandwidth. Electronic beam scanning is accomplished with a 4-bit digital phase shifter. The PAA design is processed at a center frequency of 7.5 GHz, a bandwidth exceeding 500 MHz, linear polarization and a scanning range of 45. Performance is confirmed from experimental measurements made on a fabricated test model.

  13. Development of lightweight graphite/polyimide sandwich panels, phases 3, 4 and 5

    NASA Technical Reports Server (NTRS)

    Merlette, J. B.

    1972-01-01

    Work performed in the last three phases of the program included: (1) face sheet processing; (2) honeycomb core manufacture; (3) face sheet-to-core bonding development; and (4) sandwich panel fabrication and testing. Resin cure studies were a major portion of this effort since processing problems traced to the polyimide matrix resin had to be resolved before quality core and face sheets could be fabricated. Honeycomb core fabrication and testing were conducted by Hexcel Corporation. A total of four graphite/polyimide resin composite cores were fabricated, tested, and reported. Two sandwich panels weighing .48 and .58 lb/sq ft, respectively were designed and fabricated which meet the support structure loads for the shuttle orbiter thermal protection system.

  14. Human Thrombin Detection Through a Sandwich Aptamer Microarray: Interaction Analysis in Solution and in Solid Phase

    PubMed Central

    Sosic, Alice; Meneghello, Anna; Cretaio, Erica; Gatto, Barbara

    2011-01-01

    We have developed an aptamer-based microarray for human thrombin detection exploiting two non-overlapping DNA thrombin aptamers recognizing different exosites of the target protein. The 15-mer aptamer (TBA1) binds the fibrinogen-binding site, whereas the 29-mer aptamer (TBA2) binds the heparin binding domain. Extensive analysis on the complex formation between human thrombin and modified aptamers was performed by Electrophoresis Mobility Shift Assay (EMSA), in order to verify in solution whether the chemical modifications introduced would affect aptamers/protein recognition. The validated system was then applied to the aptamer microarray, using the solid phase system devised by the solution studies. Finally, the best procedure for Sandwich Aptamer Microarray (SAM) and the specificity of the sandwich formation for the developed aptasensor for human thrombin were optimized. PMID:22163703

  15. High-Fidelity Modeling for Health Monitoring in Honeycomb Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Luchinsky, Dimitry G.; Hafiychuk, Vasyl; Smelyanskiy, Vadim; Tyson, Richard W.; Walker, James L.; Miller, Jimmy L.

    2011-01-01

    High-Fidelity Model of the sandwich composite structure with real geometry is reported. The model includes two composite facesheets, honeycomb core, piezoelectric actuator/sensors, adhesive layers, and the impactor. The novel feature of the model is that it includes modeling of the impact and wave propagation in the structure before and after the impact. Results of modeling of the wave propagation, impact, and damage detection in sandwich honeycomb plates using piezoelectric actuator/sensor scheme are reported. The results of the simulations are compared with the experimental results. It is shown that the model is suitable for analysis of the physics of failure due to the impact and for testing structural health monitoring schemes based on guided wave propagation.

  16. Graphene-sandwiched silicon structures for greatly enhanced unpolarized light absorption

    NASA Astrophysics Data System (ADS)

    Shi, Kaifeng; Haque, Riaz R.; Mao, Ling-Feng; Lu, Zhaolin

    2015-03-01

    Based on the attenuated total reflection configuration, a multi-layer graphene (MLG) sandwiched silicon structure is proposed for greatly enhancing light absorption over a broad spectral range (1000-2000 nm). At specific incident angles, the electric field in the sandwiched graphene can be simultaneously enhanced for both transverse electric (TE) and transverse magnetic (TM) polarized light. Numerical analysis and finite-difference time-domain simulation demonstrate over 80% and 70% light absorption for TE- and TM-polarized light, respectively. Owing to the unique optical properties of graphene, the absorption of any photon by graphene may give rise to an electron-hole pair. Thus, the greatly enhanced absorption of unpolarized, broadband light may find significant applications in future photovoltaic devices. However, the excess energy carried by the electron-hole pair can dissipate within a sub-picosecond due to the ultra-fast intraband carrier relaxation, which is the challenge for photovoltaic application and will also be discussed.

  17. Multilayer Roll-Bonded Sandwich: Processing, Mechanical Performance, and Bioactive Behavior

    SciTech Connect

    Palkowski H.; Stanic V.; Carrado, A.

    2012-03-30

    Multifunctionality and improving the properties of materials make it necessary to use hybrid systems such as combinations of metals with polymers. Their applications can be found in all areas where light weight and improved and adapted mechanical properties as well as high functionality are needed. Moreover, tailored types of hybrids can be interesting for biomedical applications, as under specific conditions they show, e.g., good strength combined with high elasticity. Herein, we present preliminary tests on the biomimetic behavior of AISI SS316L/polypropylene copolymer/AISI SS316L sandwich. Biomimetic coatings were produced by inducing a calcium phosphate layer in a way similar to the process of natural bone formation. Knowledge of the formability of three-layered sandwich sheets and their biomimetic behavior is presented.

  18. Analysis of a ceramic filled bio-plastic composite sandwich structure

    NASA Astrophysics Data System (ADS)

    Habib Ullah, M.; Islam, M. T.

    2013-11-01

    Design and analysis of a ceramic-filled bio-plastic composite sandwich structure is presented. This proposed high-dielectric structure is used as a substrate for patch antennas. A meandered-strip line-fed fractal-shape patch antenna is designed and fabricated on a copper-laminated sandwich-structured substrate. Measurement results of this antenna show 44% and 20% of bandwidths with maximum gains of 3.45 dBi and 5.87 dBi for the lower and upper bands, respectively. The half-power beam widths of 104 and 78 have been observed from the measured radiation pattern at the two resonance frequencies 0.9 GHz and 2.5 GHz.

  19. 250 C-Operated sandwich-structured all-SiC power module

    NASA Astrophysics Data System (ADS)

    Kato, Fumiki; Simanjorang, Rejeki; Lang, Fengqun; Nakagawa, Hiroshi; Yamaguchi, Hiroshi; Sato, Hiroshi

    2015-04-01

    The operation of a sandwich structured all-SiC power module is demonstrated at 250 C. The power module was designed by considering two thermal deformation issues. Thermally induced bending of the SiN-AMC substrates is reduced by introducing symmetrical Cu wiring patterns on both sides of the SiN ceramic plate. The concentration of stress located in the gate joint material is drastically reduced by introducing a trench structure in the Cu wiring layer of the gate interconnection. A double pulse test at a high temperature is carried out. At 250 C, the all-SiC sandwich-structured power module was successfully operate at 600 V and 15 A. The maximum switching transient speed (dV/dt) of turn-on and turn-off are observed 10.7 and 12.1 V/ns, respectively.

  20. Sandwich-type functionalized graphene sheet-sulfur nanocomposite for rechargeable lithium batteries.

    PubMed

    Cao, Yuliang; Li, Xiaolin; Aksay, Ilhan A; Lemmon, John; Nie, Zimin; Yang, Zhenguo; Liu, Jun

    2011-05-01

    A functionalized graphene sheet-sulfur (FGSS) nanocomposite was synthesized as the cathode material for lithium-sulfur batteries. The structure has a layer of functionalized graphene sheets/stacks (FGS) and a layer of sulfur nanoparticles creating a three-dimensional sandwich-type architecture. This unique FGSS nanoscale layered composite has a high loading (70 wt%) of active material (S), a high tap density of ?0.92 g cm(-3), and a reversible capacity of ?505 mAh g(-1) (?464 mAh cm(-3)) at a current density of 1680 mA g(-1) (1C). When coated with a thin layer of cation exchange Nafion film, the migration of dissolved polysulfide anions from the FGSS nanocomposite was effectively reduced, leading to a good cycling stability of 75% capacity retention over 100 cycles. This sandwich-structured composite conceptually provides a new strategy for designing electrodes in energy storage applications. PMID:21448499

  1. Microstructure evolution process of Ferro-Aluminum based sandwich composite for electromagnetic shielding.

    PubMed

    Luo, Zhichao; Zhang, Qiang; Ma, Xiangyu; Wu, Gaohui

    2014-09-01

    In this paper, sandwich composite (SWC) with Fe-Al soft magnetic alloy sandwiched between pure iron substrates was proposed and fabricated by hot pressing and diffusion treatment. The microstructure evolution process of the composite was investigated. Fe/Fe2Al5/Fe diffusion couple was obtained at 700 C and subsequently kept at 900 C for further isothermal diffusion. During the diffusion reactive process, we confirmed that major FeAl2 and minor Fe4Al13 were produced when Fe2Al5 dissolved. After 10h of diffusion treatment, FeAl and ?-Fe(Al) were the only two intermetallic phases left. Except FeAl2, the thickness of each intermetallic layer held good parabolic relationship with the diffusion annealing time. PMID:24981211

  2. Analysis of a ceramic filled bio-plastic composite sandwich structure

    SciTech Connect

    Habib Ullah, M. [Institute of Space Science (ANGKASA), Universiti Kebangsaan Malaysia, Bangi Selangor 43600 (Malaysia) [Institute of Space Science (ANGKASA), Universiti Kebangsaan Malaysia, Bangi Selangor 43600 (Malaysia); Department of Electrical, Electronic and System Engineering, Universiti Kebangsaan Malaysia, Bangi 43600 (Malaysia); Islam, M. T. [Institute of Space Science (ANGKASA), Universiti Kebangsaan Malaysia, Bangi Selangor 43600 (Malaysia)] [Institute of Space Science (ANGKASA), Universiti Kebangsaan Malaysia, Bangi Selangor 43600 (Malaysia)

    2013-11-25

    Design and analysis of a ceramic-filled bio-plastic composite sandwich structure is presented. This proposed high-dielectric structure is used as a substrate for patch antennas. A meandered-strip line-fed fractal-shape patch antenna is designed and fabricated on a copper-laminated sandwich-structured substrate. Measurement results of this antenna show 44% and 20% of bandwidths with maximum gains of 3.45 dBi and 5.87 dBi for the lower and upper bands, respectively. The half-power beam widths of 104 and 78 have been observed from the measured radiation pattern at the two resonance frequencies 0.9 GHz and 2.5?GHz.

  3. Analysis of Sandwich Shells with Metallic Foam Cores based on the Uniaxial Tensile Test

    SciTech Connect

    Mata, H.; Fernandes, A. A.; Parente, M. P. L.; Jorge, R. Natal [IDMEC-FEUP, Rua Dr. Roberto Frias, 4200-465, Porto (Portugal); Santos, A. [INEGI, Rua Dr. Roberto Frias, 4200-465, Porto (Portugal); Valente, R. A. F. [Universidade de Aveiro, Campus Universitario de Santiago, 3810-193, Aveiro (Portugal)

    2011-05-04

    On this work, the authors present the development and evaluation of an innovative system able to perform reliable panels of sandwich sheets with metallic foam cores for industrial applications, especially in automotive and aeronautical industries. This work is divided into two parts; in the first part the mathematical model used to describe the behavior of sandwich shells with metal cores form is presented and some numerical examples are presented. In the second part of this work, the numerical results are validated using the experimental results obtained from the mechanical experiments. Using the isotropic hardening crushable foam constitutive model, available on ABAQUS, a set of different mechanical tests were simulated. The isotropic hardening model available uses a yield surface that is an ellipse centered at the origin in the p-q stress plane. Using this constitutive model, the uniaxial tensile test for this material was simulated, and a comparison with the experimental results was made.

  4. Single and Multisite Impact Response of S2-Glass/Epoxy Balsa Wood Core Sandwich Composites

    NASA Astrophysics Data System (ADS)

    Vaidya, Uday K.; Deka, Lakshya J.

    Impact damage reduces the structural integrity and load bearing capacity of a composite structure. Most studies on high velocity impact damage have been limited to single-site impacts, with little consideration given to the effect of cumulative damage from multiple impacts. In this study, the impact damage response of S2-glass/epoxy balsa wood core sandwich composite is evaluated experimentally and supported by finite element modeling for single-site and multi-site impacts from 0.30 and 0.50 caliber spherical projectiles. During high velocity impact, a composite laminate undergoes progressive damage;hence a progressive failure model based on Hashin's criteria is used to predict failure. When subjected to multi-site impact loading, a sandwich composite structure exhibits synergistic and cumulative damage causing extensive fiber breakage, matrix cracking and delamination. An excellent correlation between experimental and numerical results is obtained.

  5. The Dynamic Characteristics of 3-D Superconducting Actuator Using the Magnetized HTS Bulk by Sandwiched Electromagnets

    NASA Astrophysics Data System (ADS)

    Nakano, H.; Kim, S. B.; Ozasa, S.; Sawae, M.

    The electric device applications of a high temperature superconducting (HTS) bulk, having stable levitation and suspension properties due to their strong flux pinning force, have been proposed and developed. We have been investigating the three-dimensional (3-D) superconducting actuator using HTS bulk to develop a non-contact transportation device. In our previous works, the overshooting of the HTS bulk mover magnetized by 2-D arranged electromagnets were observed. Therefore, the new magnetization method using sandwiched electromagnets was purposed in order to solve the overshooting problems of HTS bulk mover. In this paper, the dynamic stabilities on the rotating and horizontal moving of the HTS bulk mover magnetized by sandwiched electromagnets was investigated experimentally, and the maximum moving displacements and convergence times during the overshooting state were reduced by proposed magnetization method with small magnetizing current.

  6. Boom Construction

    NSDL National Science Digital Library

    AMPS GK-12 Program,

    Student teams design their own booms (bridges) and engage in a friendly competition with other teams to test their designs. Each team strives to design a boom that is light, can hold a certain amount of weight, and is affordable to build. Teams are also assessed on how close their design estimations are to the final weight and cost of their boom "construction." This activity teaches students how to simplify the math behind the risk and estimation process that takes place at every engineering firm prior to the bidding phasewhen an engineering firm calculates how much money it will take to build the project and then "bids" against other competitors.

  7. Nonpolar resistance switching of metal\\/binary-transition-metal oxides\\/metal sandwiches: Homogeneous\\/inhomogeneous transition of current distribution

    Microsoft Academic Search

    I. H. Inoue; S. Yasuda; H. Akinaga; H. Takagi

    2008-01-01

    Exotic features of a metal\\/oxide\\/metal sandwich, which will be the basis for a drastically innovative nonvolatile memory device, is brought to light from a physical point of view. Here the insulator is one of the ubiquitous and classic binary-transition-metal oxides (TMO), such as Fe2O3 , NiO , and CoO . The sandwich exhibits a resistance that reversibly switches between two

  8. Analysis of Thick Sandwich Shells with Embedded Ceramic Tiles

    NASA Technical Reports Server (NTRS)

    Davila, Carlos G.; Smith, C.; Lumban-Tobing, F.

    1996-01-01

    The Composite Armored Vehicle (CAV) is an advanced technology demonstrator of an all-composite ground combat vehicle. The CAV upper hull is made of a tough light-weight S2-glass/epoxy laminate with embedded ceramic tiles that serve as armor. The tiles are bonded to a rubber mat with a carefully selected, highly viscoelastic adhesive. The integration of armor and structure offers an efficient combination of ballistic protection and structural performance. The analysis of this anisotropic construction, with its inherent discontinuous and periodic nature, however, poses several challenges. The present paper describes a shell-based 'element-layering' technique that properly accounts for these effects and for the concentrated transverse shear flexibility in the rubber mat. One of the most important advantages of the element-layering technique over advanced higher-order elements is that it is based on conventional elements. This advantage allows the models to be portable to other structural analysis codes, a prerequisite in a program that involves the computational facilities of several manufacturers and government laboratories. The element-layering technique was implemented into an auto-layering program that automatically transforms a conventional shell model into a multi-layered model. The effects of tile layer homogenization, tile placement patterns, and tile gap size on the analysis results are described.

  9. Clay Nanocomposite/Aerogel Sandwich Structures for Cryotanks

    NASA Technical Reports Server (NTRS)

    Miller, Sandi; Leventis, Nicholas; Johnston, J. Chris; Meador, Michael

    2006-01-01

    GRC research has led to the development of epoxy-clay nanocomposites with 60-70% lower gas permeability than the base epoxy resin. Filament wound carbon fiber reinforced tanks made with this nanocomposite had a five-fold lower helium leak rate than the corresponding tanks made without clay. More recent work has produced new composites with more than a 100-fold reduction in helium permeability. Use of these advanced, high barrier composites would eliminate the need for a liner in composite cryotanks, thereby simplifying construction and reducing propellant leakage. Aerogels are attractive materials for use as cryotank insulation because of their low density and low thermal conductivity. However, aerogels are fragile and have poor environmental stability, which have limited their use to certain applications in specialized environments (e.g., in certain types of nuclear reactors as Cerenkov radiation detectors, and as thermal insulators aboard space rovers on Mars). New GRC developed polymer crosslinked aerogels (X-Aerogels) retain the low density of conventional aerogels, but they demonstrate a 300-fold increase in their mechanical strength. Currently, our strongest materials combine a density of approx. 0.45 g/cc, a thermal conductivity of approx. 0.04 W/mK and a compressive strength of 185 MPa. Use of these novel aerogels as insulation materials/structural components in combination with the low permeability of epoxy-clay nanocomposites could significantly reduce cryotank weight and improve durability.

  10. Double antibody sandwich enzyme linked immunoassay and rapid Immunoswab assay for detection of gliadin in food

    Microsoft Academic Search

    Hoon H. Sunwoo; Naiyana Gujral; Susan Lutz; Mavanur Suresh

    2011-01-01

    Celiac (gluten intolerant) sprue is a life-long threatening disease. The only effective treatment thus far is to maintain a gluten-free diet. Sensitive and reliable double antibody sandwich enzyme-linked immunosorbent assay (ELISA) and Immunoswab assay were developed by using chicken egg yolk anti-gliadin immunoglobulin Y as capturing antibody and monoclonal anti-gliadin IgG (HYB-314) antibody as detecting antibody for the detection of

  11. Double antibody sandwich enzyme linked immunoassay and rapid Immunoswab assay for detection of gliadin in food

    Microsoft Academic Search

    Hoon H. Sunwoo; Naiyana Gujral; Susan Lutz; Mavanur Suresh

    2012-01-01

    Celiac (gluten intolerant) sprue is a life-long threatening disease. The only effective treatment thus far is to maintain a gluten-free diet. Sensitive and reliable double antibody sandwich enzyme-linked immunosorbent assay (ELISA) and Immunoswab assay were developed by using chicken egg yolk anti-gliadin immunoglobulin Y as capturing antibody and monoclonal anti-gliadin IgG (HYB-314) antibody as detecting antibody for the detection of

  12. The use of ANSYS to calculate the behaviour of sandwich structures

    Microsoft Academic Search

    Vincent Manet

    1998-01-01

    In this article, we use different models to compute displacements and stresses of a simply supported sandwich beam subjected to a uniform pressure. 8-node quadrilateral elements (Plane 82), multi-layered 8-node quadrilateral shell elements (Shell 91) and multi-layered 20-node cubic elements (Solid 46) are used. The influence of mesh refinement and of the ratio of Young's moduli of the layers are

  13. Conformal ``thin sandwich'' data for the initial-value problem of general relativity

    E-print Network

    James W. York, Jr

    1998-12-23

    The initial-value problem is posed by giving a conformal three-metric on each of two nearby spacelike hypersurfaces, their proper-time separation up to a multiplier to be determined, and the mean (extrinsic) curvature of one slice. The resulting equations have the {\\it same} elliptic form as does the one-hypersurface formulation. The metrical roots of this form are revealed by a conformal ``thin sandwich'' viewpoint coupled with the transformation properties of the lapse function.

  14. An analytical and experimental investigation of sandwich composites subjected to low-velocity impact

    Microsoft Academic Search

    Todd Alan Anderson

    1999-01-01

    This study involves an experimental and analytical investigation of low-velocity impact phenomenon in sandwich composite structures. The analytical solution of a three-dimensional finite-geometry multi-layer specially orthotropic panel subjected to static and transient transverse loading cases is presented. The governing equations of the static and dynamic formulations are derived from Reissner's functional and solved by enforcing the continuity of traction and

  15. Low velocity impact analysis of composite sandwich shells using higher-order shear deformation theories

    Microsoft Academic Search

    Dipak K Maiti; P K Sinha

    1996-01-01

    In the present investigation, higher-order and conventional first-order shear deformation theories are used to study the impact\\u000a response of composite sandwich shells. The formulation is based on Donnells shallow shell theory. Nine-noded Lagrangian elements\\u000a are used for the finite element formulation. A modified Hertzian contact law is used to calculate the contact force. The results\\u000a obtained from the present investigation

  16. Dynamic analysis of an elasto-plastic sandwich subjected to low velocity impact

    Microsoft Academic Search

    Mondher Wali; Moez Abdennadher; Tahar Fakhfakh; Mohamed Haddar

    2011-01-01

    Purpose The purpose of this paper is to analyse the dynamic behaviour of an elasto-plastic sandwich subjected to low velocity impact. Design\\/methodology\\/approach A numerical model is developed with the assumption that the plastic deformation is confined under the contact area. The structure is analyzed using the in-house finite element code with an appropriate contact law. During the impact

  17. Atomically thick pt-cu nanosheets: self-assembled sandwich and nanoring-like structures.

    PubMed

    Saleem, Faisal; Xu, Biao; Ni, Bing; Liu, Huiling; Nosheen, Farhat; Li, Haoyi; Wang, Xun

    2015-03-01

    Atomically thick and flexible Pt-Cu alloy nanosheets are prepared and loaded with either Pd or Pt to produce sandwich structures or nanoring-like nanosheet structures, respectively. Core-shell alloy nanoparticles containing Rh, Ir, and Ru are also prepared. All of these structures exhibit superior specific and mass activities for the oxidation of formic acid for fuel cells for portable electronic devices as compared to commercial Pd/C catalyst. PMID:25677842

  18. Kinetic analysis of the interfacial reactions in Ni\\/Sn\\/Cu sandwich structures

    Microsoft Academic Search

    S. J. Wang; C. Y. Liu

    2006-01-01

    The mutual interaction between Sn\\/Ni and Sn\\/Cu interfacial reactions in a Ni\\/Sn\\/Cu sandwich sample has been studied. The major\\u000a interfacial reaction product on the Cu side was Cu6Sn5, while on the Ni side, a ternary (Cu,Ni)6Sn5 compound layer was formed. We found that the growth kinetics of the interfacial compound layers on both sides reached a steady\\u000a state in the

  19. Kinetic analysis of the interfacial reactions in Ni\\/Sn\\/Cu sandwich structures

    Microsoft Academic Search

    S. J. Wang; C. Y. Liu

    2006-01-01

    The mutual interaction between Sn\\/Ni and Sn\\/Cu interfacial reactions in a Ni\\/Sn\\/Cu sandwich sample has been studied. The major interfacial reaction product on the Cu side was Cu6Sn5, while on the Ni side, a ternary (Cu,Ni)6Sn5 compound layer was formed. We found that the growth kinetics of the interfacial compound layers on both sides reached a steady state in the

  20. Governing equations for vibrating constrained-layer damping sandwich plates and beams.

    NASA Technical Reports Server (NTRS)

    Yan, M.-J.; Dowell, E. H.

    1972-01-01

    A simple differential equation is derived to describe constrained-layer damping in nonsymmetric sandwich plates and beams composed of isotropic and homogeneous layers. The natural boundary conditions related to this equation are determined and some typical numerical results obtained by this equation are given. The equation is valid within the linear theories of elasticity and viscoelasticity in the absence of any constraints on thicknesses, positions, symmetries, and densities of the layers.

  1. A novel sandwiched membrane as polymer electrolyte for lithium ion battery

    Microsoft Academic Search

    H. P. Zhang; P. Zhang; Z. H. Li; M. Sun; Y. P. Wu; H. Q. Wu

    2007-01-01

    A novel kind of sandwiched polymer membrane was prepared by coating three layers of poly(vinyl difluoride) (PVDF), poly(methyl methacrylate) (PMMA) and PVDF, separately. Its characteristics were investigated by scanning electron microscopy, FT-IR, X-ray diffraction, and differential thermal analysis. It consists of two phases. The outer PVDF layers are porous, and the inner PMMA layer is solid. Since the PMMA has

  2. Molecular Organization of Amyloid Protofilament-Like Assembly of Betabellin 15D: Helical Array of ?-Sandwiches

    Microsoft Academic Search

    Hideyo Inouye; Jeremy E. Bond; Sean P. Deverin; Amareth Lim; Catherine E. Costello; Daniel A. Kirschner

    2002-01-01

    Betabellin is a 32-residue peptide engineered to fold into a four-stranded antiparallel ?-sheet protein. Upon air oxidation, the betabellin peptides can fold and assemble into a disulfide-bridged homodimer, or ?-sandwich, of 64 residues. Recent biophysical and ultrastructural studies indicate that betabellin 15D (B15D) (a homodimer of HSLTAKIpkLTFSIAphTYTCAVpkYTAKVSH, where p=DPro, k=DLys, and h=DHis) forms unbranched, 35- wide assemblies that resemble the

  3. Sandwich layer composite prepared by a novel zero-shrinkage-difference technology

    Microsoft Academic Search

    Xiangchun Liu; Feng Gao; Changsheng Tian

    2009-01-01

    The mismatch in sintering kinetics between different ceramics may cause camber or cracks in achieving chip multilayer composites. It is a challenge to find the solution to eliminate the camber or cracks in co-fired composites without the degradation. To solve this problem, a novel zero-shrinkage-difference technique is introduced. According to this philosophy, the sandwich structure of ZMT3 dielectric\\/NZC ferrite multilayer

  4. Origins of giant biquadratic coupling in CoFe\\/Mn\\/CoFe sandwich structures (abstract)

    Microsoft Academic Search

    Norman C. Koon

    1996-01-01

    Recently Filipkowski etal. reported extremely strong, near 90 degree coupling of 2.5 erg\\/cm2 for epitaxial sandwiches of CoFe\\/Mn\\/CoFe, where the CoFe composition was chosen to be a good lattice match to Mn. Both CoFe and Mn have the bcc structure, but Mn is antiferromagnetic while CoFe is ferromagnetic. It was found that the data were very well described by a

  5. Anomalous dispersion of SH acoustic waves in a piezoelectric sandwich structure

    Microsoft Academic Search

    V. I. Alshits; V. N. Lyubimov

    2003-01-01

    A transformation of the dispersion spectrum of shear horizontal (SH) acoustic eigenwaves in a sandwich structure due to a\\u000a piezoelectric effect is described. The structure consists of two plates separated by a gap whose thickness is considerably\\u000a less than the wavelength. Under these conditions, acoustic fields induced in the plates interact through the piezoelectric\\u000a effect. The piezoelectric effect brings about

  6. Engineering of betabellin 15D: Copper(II)-induced folding of a fibrillar ?-sandwich protein

    Microsoft Academic Search

    Amareth Lim; Matthew J. Saderholm; Mathias Kroll; Yibing Yan; Bruce W. Erickson; Philippe A. Guy; Robert J. Anderegg; Alexander M. Makhov; Jack D. Griffith

    1999-01-01

    The inverse protein-folding problem has been explored by designing de novo the betabellin target structure (a 64-residue -sandwich protein), synthesizing a 32-residue peptide chain (HSLTAKIpkLTFSIAphTYTCAVpkYTAKVSH, where p = DPro, k = DLys, and h = DHis) that might fold into this structure, and studying how its disulfide-bridged form (betabellin 15D) folds in 10 mM ammonium acetate with and without Cu2+.

  7. Aptamer-conjugated silver nanoparticles for electrochemical dual-aptamer-based sandwich detection of staphylococcus aureus.

    PubMed

    Abbaspour, Abdolkarim; Norouz-Sarvestani, Fatemeh; Noori, Abolhassan; Soltani, Noushin

    2015-06-15

    Staphylococcus aureus (S. aureus) is one of the most important human pathogens and causes numerous illnesses. In this study, we report a sensitive and highly selective dual-aptamer-based sandwich immunosensor for the detection of S. aureus. In this bioassay system, a biotinylated primary anti-S.aureus aptamer was immobilized on streptavidin coated magnetic beads (MB), which serves as a capture probe. A secondary anti-S.aureus aptamer was conjugated to silver nanoparticles (Apt-AgNP) that sensitively reports the detection of the target. In the presence of target bacterium, an Apt/S.aureus/apt-AgNP sandwich complex is formed on the MB surface and the electrochemical signal of AgNPs followed through anodic stripping voltammetry. The proposed sandwich assay benefits from advantageous of a sandwich assay for increased specificity, MB as carriers of affinity ligands for solution-phase recognition and fast magnetic separation, AgNPs for signal amplification, and an electrochemical stripping voltammetry read-out as a simple and sensitive detection. The electrochemical immunosensor shows an extended dynamic range from 10 to 110(6)cfu/mL with a low detection limit of 1.0cfu/mL (S/N=3). Furthermore, the possible interference of other analog bacteria was studied. To assess the general applicability of this sensor, we investigated the quantification of S. aureus in real water samples. The results were compared to the experimental results obtained from a plate counting method, which demonstrated an acceptable consistency. PMID:25562742

  8. Contact transparency inducing low bias negative differential resistance in two capped carbon nanotubes sandwiching ? barrier

    NASA Astrophysics Data System (ADS)

    Min, Y.; Fang, J. H.; Zhong, C. G.; Dong, Z. C.; Li, J. F.; Yao, K. L.; Zhou, L. P.

    2015-01-01

    A first-principles study of the transport properties of two capped (5, 5) carbon nanotubes sandwiching ? barrier is reported. Contact transparency at zero bias is obtained. Strong negative differential resistance effect with large peak-to-valley ratio of 1,124 % is present under very low bias, which may promise the potential applications in nano-electronic devices with low power dissipation in the future.

  9. Design of Fiber Reinforced Foam Sandwich Panels for Large Ares V Structural Applications

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M.; Hopkins, Dale A.

    2010-01-01

    The preliminary design of three major structural components within NASA's Ares V heavy lift vehicle using a novel fiber reinforced foam composite sandwich panel concept is presented. The Ares V payload shroud, interstage, and core intertank are designed for minimum mass using this panel concept, which consists of integral composite webs separated by structural foam between two composite facesheets. The HyperSizer structural sizing software, in conjunction with NASTRAN finite element analyses, is used. However, since HyperSizer does not currently include a panel concept for fiber reinforced foam, the sizing was performed using two separate approaches. In the first, the panel core is treated as an effective (homogenized) material, whose properties are provided by the vendor. In the second approach, the panel is treated as a blade stiffened sandwich panel, with the mass of the foam added after completion of the panel sizing. Details of the sizing for each of the three Ares V components are given, and it is demonstrated that the two panel sizing approaches are in reasonable agreement for thinner panel designs, but as the panel thickness increases, the blade stiffened sandwich panel approach yields heavier panel designs. This is due to the effects of local buckling, which are not considered in the effective core property approach.

  10. Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

    NASA Technical Reports Server (NTRS)

    Ryan, S.; Ordonez, E.; Christiansen, E. L.; Lear, D. M.

    2010-01-01

    Open cell metallic foam core sandwich panel structures are of interest for application in spacecraft micrometeoroid and orbital debris shields due to their novel form and advantageous structural and thermal performance. Repeated shocking as a result of secondary impacts upon individual foam ligaments during the penetration process acts to raise the thermal state of impacting projectiles ; resulting in fragmentation, melting, and vaporization at lower velocities than with traditional shielding configurations (e.g. Whipple shield). In order to characterize the protective capability of these structures, an extensive experimental campaign was performed by the Johnson Space Center Hypervelocity Impact Technology Facility, the results of which are reported in this paper. Although not capable of competing against the protection levels achievable with leading heavy shields in use on modern high-risk vehicles (i.e. International Space Station modules), metallic foam core sandwich panels are shown to provide a substantial improvement over comparable structural panels and traditional low weight shielding alternatives such as honeycomb sandwich panels and metallic Whipple shields. A ballistic limit equation, generalized in terms of panel geometry, is derived and presented in a form suitable for application in risk assessment codes.

  11. An efficient FE model based on combined theory for the analysis of soft core sandwich plate

    NASA Astrophysics Data System (ADS)

    Khandelwal, Ravi Prakash; Chakrabarti, Anupam; Bhargava, Pradeep

    2013-05-01

    An efficient C0 continuous finite element (FE) model is developed based on combined theory (refine higher order shear deformation theory (RHSDT) and least square error (LSE) method) for the static analysis of soft core sandwich plate. In this (RHSDT) theory, the in-plane displacement field for the face sheets and the core is obtained by superposing a global cubically varying displacement field on a zig-zag linearly varying displacement field with a different slope in each layer. The transverse displacement assumes to have a quadratic variation within the core and it remains constant in the faces beyond the core. The proposed model satisfies the condition of transverse shear stress continuity at the layer interfaces and the zero transverse shear stress condition at the top and bottom of the sandwich plate. The nodal field variables are chosen in an efficient manner to circumvent the problem of C1 continuity requirement of the transverse displacements. In order to calculate the accurate through thickness transverse stresses variation, LSE method has been used at the post processing stage. The proposed combine model (RHSDT and LSE) is implemented to analyze the laminated composites and sandwich plates. Many new results are also presented which should be useful for future research.

  12. Sizing Single Cantilever Beam Specimens for Characterizing Facesheet/Core Peel Debonding in Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.

    2010-01-01

    This technical publication details part of an effort focused on the development of a standardized facesheet/core peel debonding test procedure. The purpose of the test is to characterize facesheet/core peel in sandwich structure, accomplished through the measurement of the critical strain energy release rate associated with the debonding process. Following an examination of previously developed tests and a recent evaluation of a selection of these methods, a single cantilever beam (SCB) specimen was identified as being a promising candidate for establishing such a standardized test procedure. The objective of the work described here was to begin development of a protocol for conducting a SCB test that will render the procedure suitable for standardization. To this end, a sizing methodology was developed to ensure appropriate SCB specimen dimensions are selected for a given sandwich system. Application of this method to actual sandwich systems yielded SCB specimen dimensions that would be practical for use. This study resulted in the development of a practical SCB specimen sizing method, which should be well-suited for incorporation into a standardized testing protocol.

  13. Computation of linear transmittance of thermal bridges in precast concrete sandwich panels

    NASA Astrophysics Data System (ADS)

    Luscietti, Davide; Gervasio, Paola; Lezzi, Adriano M.

    2014-11-01

    Precast concrete lightened sandwich panels are widely used building elements. They are made by two concrete wythes separated by a layer of lightweight material: the central layer is inhomogeneous due to the presence of concrete ribs which tie the external wythe and act as thermal bridges. Computation of thermal transmittance of sandwich panels is clearly described in European Standards, but in many cases it requires numerical simulations to determine the linear transmittance ? associated with lightweight material-concrete interfaces in the inhomogeneous layer. Although simple, these simulations represent a critical issue for many panel manufacturers and they would much rather prefer correlations to compute ?. In this work we present a correlation based on an artificial neural network (ANN) to estimate linear trasmittauce values for current Italian sandwich panel production. Five input parameters are considered: rib width, lightweight material conductivity, and thickness of the three panel layers. To obtain the data which are necessary to train and test the ANN, a fast and accurate Spectral Element Method is used to solve Laplace equation in the neighborhood of a rib. 5460 ? values are collected which ensure an accurate network response.

  14. Efficient Design and Analysis of Lightweight Reinforced Core Sandwich and PRSEUS Structures

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Yarrington, Phillip W.; Lucking, Ryan C.; Collier, Craig S.; Ainsworth, James J.; Toubia, Elias A.

    2012-01-01

    Design, analysis, and sizing methods for two novel structural panel concepts have been developed and incorporated into the HyperSizer Structural Sizing Software. Reinforced Core Sandwich (RCS) panels consist of a foam core with reinforcing composite webs connecting composite facesheets. Boeing s Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) panels use a pultruded unidirectional composite rod to provide axial stiffness along with integrated transverse frames and stitching. Both of these structural concepts are ovencured and have shown great promise applications in lightweight structures, but have suffered from the lack of efficient sizing capabilities similar to those that exist for honeycomb sandwich, foam sandwich, hat stiffened, and other, more traditional concepts. Now, with accurate design methods for RCS and PRSEUS panels available in HyperSizer, these concepts can be traded and used in designs as is done with the more traditional structural concepts. The methods developed to enable sizing of RCS and PRSEUS are outlined, as are results showing the validity and utility of the methods. Applications include several large NASA heavy lift launch vehicle structures.

  15. Finite element based stability-constrained weight minimization of sandwich composite ducts for airship applications

    NASA Astrophysics Data System (ADS)

    Khode, Urmi B.

    High Altitude Long Endurance (HALE) airships are platform of interest due to their persistent observation and persistent communication capabilities. A novel HALE airship design configuration incorporates a composite sandwich propulsive hull duct between the front and the back of the hull for significant drag reduction via blown wake effects. The sandwich composite shell duct is subjected to hull pressure on its outer walls and flow suction on its inner walls which result in in-plane wall compressive stress, which may cause duct buckling. An approach based upon finite element stability analysis combined with a ply layup and foam thickness determination weight minimization search algorithm is utilized. Its goal is to achieve an optimized solution for the configuration of the sandwich composite as a solution to a constrained minimum weight design problem, for which the shell duct remains stable with a prescribed margin of safety under prescribed loading. The stability analysis methodology is first verified by comparing published analytical results for a number of simple cylindrical shell configurations with FEM counterpart solutions obtained using the commercially available code ABAQUS. Results show that the approach is effective in identifying minimum weight composite duct configurations for a number of representative combinations of duct geometry, composite material and foam properties, and propulsive duct applied pressure loading.

  16. Failure Maps for Rectangular 17-4PH Stainless Steel Sandwiched Foam Panels

    NASA Technical Reports Server (NTRS)

    Raj, S. V.; Ghosn, L. J.

    2007-01-01

    A new and innovative concept is proposed for designing lightweight fan blades for aircraft engines using commercially available 17-4PH precipitation hardened stainless steel. Rotating fan blades in aircraft engines experience a complex loading state consisting of combinations of centrifugal, distributed pressure and torsional loads. Theoretical failure plastic collapse maps, showing plots of the foam relative density versus face sheet thickness, t, normalized by the fan blade span length, L, have been generated for rectangular 17-4PH sandwiched foam panels under these three loading modes assuming three failure plastic collapse modes. These maps show that the 17-4PH sandwiched foam panels can fail by either the yielding of the face sheets, yielding of the foam core or wrinkling of the face sheets depending on foam relative density, the magnitude of t/L and the loading mode. The design envelop of a generic fan blade is superimposed on the maps to provide valuable insights on the probable failure modes in a sandwiched foam fan blade.

  17. Ambient temperature fatigue tests of elements of an actively cooled honeycomb sandwich structural panel

    NASA Technical Reports Server (NTRS)

    Sharpe, E. L.; Elber, W.

    1977-01-01

    Elements of an actively cooled structural panel for a hypersonic aircraft have been investigated for fatigue characteristics. The study involved a bonded honeycomb sandwich panel with d-shaped coolant tubes. The curved portion of these tubes was embedded in the honeycomb, and the flat portion was bonded or soldered to the inner surface of the outer skin. The elements examined were two plain skin specimens (aluminum alloy); two specimens with skins attached to manifolds and tubes (one specimen was bonded, the other soldered); and a specimen representative of a corner section of the complete cooled sandwich. Sinusoidal loads were applied to all specimens. The honeycomb sandwich specimen was loaded in both tension and compression; the other specimens were loaded in tension only. The cooling tubes were pressurized with oil throughout the fatigue tests. The most significant results of these tests follow: All specimens exceeded their design life of 20,000 cycles without damage. Crack growth rates obtained in the plain skin specimens were used to determine the crack growth characteristics of aluminum alloy. Cracks in skins either bonded or soldered to cooling tubes propagated past the tubes without penetration. The coolant tubes served as crack arresters and temporarily stopped crack growth when a crack reached a tube-skin interface. The honeycomb core demonstrated that it could contain leakage from a tube.

  18. Sandwiched polymer fibre in fibrin matrices for the dictation of endothelial cells undergoing angiogenesis

    NASA Astrophysics Data System (ADS)

    Sukmana, I.; Djuansjah, J. R. P.

    2013-04-01

    We present here a three-dimensional (3D) sandwich system made by poly(ethylene terephthalate) (PET) fibre and fibrin extracellular matrix (ECM) for endothelial cell dictation and angiogenesis guidance. In this three-dimensional system, Human Umbilical Vein Endothelial cells (HUVECs) were firstly cultured for 2 (two) days to cover the PET fibre before sandwiched in two layer fibrin gel containing HUVECs. After 4 (four) days of culture, cel-to-cel connection, tube-like structure and multi-cellular lumen formation were then assessed and validated. Phase contrast and fluorescence imaging using an inverted microscope were used to determine cell-to-cell and cell-ECM interactions. Laser scanning confocal microscopy and histological techniques were used to confirm the development of tube-like structure and multi-cellular lumen formation. This study shows that polymer fibres sandwiched in fibrin gel can be used to dictate endothelial cells undergoing angiogenesis with potential application in cancer and cardiovascular study and tissue engineering vascularisation.

  19. Process Factors and Edgewise Compressive Properties of Scarf-repaired Honeycomb Sandwich Structures

    NASA Astrophysics Data System (ADS)

    Liu, Sui; Guan, Zhidong; Guo, Xia; Sun, Kai; Kong, Jiaoyue; Yan, Dongxiu

    2014-10-01

    Bonded repairs were conducted on flat and edge-closed composite sandwich panels that had undergone different levels of initial damage, and edgewise compression behaviors of repaired panel were tested. Experimental results indicate that these repair techniques can restore the compression performance of damaged panels effectively. The repaired specimens recovered an average of over 83 % of their strength. A k-sample Anderson-Darling test was used to analyze the influence of various parameters, including curing temperature, curing pressure, and repair configurations. After a thorough comparison, it was concluded that a high-temperature, high-pressure treatment can improve the mechanical performance of repaired panels, but the improvement is closely related to the structural complexity of the repaired region. A double-side repair scheme could be used to prevent the degradation of mechanical performance caused by the additional bending moment. The conclusions drawn in the present study provide further insight into the mechanical performance of repaired sandwich panels under edgewise compressive loads. These data facilitate the improved design methodology on bonded repair of composite sandwich structures.

  20. Experimental investigation of graphite/polyimide sandwich panels in edgewise compression

    NASA Technical Reports Server (NTRS)

    Camarda, C. J.

    1980-01-01

    The local and general buckling behavior of graphite/polyimide sandwich panels simply supported along all four edges and loaded in uniaxial edgewise compression was investigated. Material properties of adhesive and facings were determined from flatwise tension and sandwich beam flexure tests. Tensile and compressive material properties of the facings were determined at 116, R.T., and 589 K (-250, R.T., and 600 F) using the sandwich beam flexure test method. Results indicate that Gr/PI is a usable structural material for short term use at temperatures as high as 589 K (600 F). Buckling specimens were 30.5 X 33.0 cm (12 x 13 in.), had quasi-isotropic symmetric facings and a glass/polyimide honeycomb core. Core thicknesses varied and three panels of each thickness were tested in edgewise compression at room temperature to investigate failure modes and corresponding buckling formulas. Specimens 0.635 cm (0.25 in.) thick failed by overall buckling at loads close to the analytically predicted buckling load; all other panels failed by face wrinkling. Results of the winkling tests indicate that several buckling formulas were unconservative and therefore not suitable for design purposes; recommended wrinkling equations are presented.

  1. Sound Transmission Loss Through a Corrugated-Core Sandwich Panel with Integrated Acoustic Resonators

    NASA Technical Reports Server (NTRS)

    Schiller, Noah H.; Allen, Albert R.; Zalewski, Bart F; Beck, Benjamin S.

    2014-01-01

    The goal of this study is to better understand the effect of structurally integrated resonators on the transmission loss of a sandwich panel. The sandwich panel has facesheets over a corrugated core, which creates long aligned chambers that run parallel to the facesheets. When ports are introduced through the facesheet, the long chambers within the core can be used as low-frequency acoustic resonators. By integrating the resonators within the structure they contribute to the static load bearing capability of the panel while also attenuating noise. An analytical model of a panel with embedded resonators is derived and compared with numerical simulations. Predictions show that acoustic resonators can significantly improve the transmission loss of the sandwich panel around the natural frequency of the resonators. In one configuration with 0.813 m long internal chambers, the diffuse field transmission loss is improved by more than 22 dB around 104 Hz. The benefit is achieved with no added mass or volume relative to the baseline structure. The embedded resonators are effective because they radiate sound out-of-phase with the structure. This results in destructive interference, which leads to less transmitted sound power.

  2. Use of the skin sandwich technique to probe the role of the hair follicles in sonophoresis.

    PubMed

    Sarheed, Omar; Frum, Yakov

    2012-02-28

    The human skin sandwich technique was used to explore the effect of brief ultrasound exposure on the transfollicular pathway of absorption. Hydrocortisone was used as a model drug. In order to calculate the permeability coefficient of hydrocortisone, its concentration at saturation in the PBS donor solution was determined. Skin samples were prepared by sandwich technique with total hydration of the epidermal and sandwich membranes. The skin was sonicated for 0 s (control), 30 s or 45 s using a pulsed mode (10% duty cycle) with the spatial and temporal average intensity (SATA) of 3.7 W/cm(2). The transducer was then removed and permeation was allowed to proceed for 52 h. Then the percentage follicular contribution was determined. It was determined that without ultrasound, drug entry into follicles accounted for 46% of total penetration. As the duration of sonication increased, the follicular contribution fell to zero even though total transepidermal flux dramatically increased. This is explained by ultrasound exposure causing sloughing off of the uppermost stratum corneum. This permeabilises the continuous surface but at the same time the disturbed cornceocytes will plug hair follicle orifices. PMID:22209999

  3. Open-Mode Debonding Analysis of Curved Sandwich Panels Subjected to Heating and Cryogenic Cooling on Opposite Faces

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    1999-01-01

    Increasing use of curved sandwich panels as aerospace structure components makes it vital to fully understand their thermostructural behavior and identify key factors affecting the open-mode debonding failure. Open-mode debonding analysis is performed on a family of curved honeycomb-core sandwich panels with different radii of curvature. The curved sandwich panels are either simply supported or clamped, and are subjected to uniform heating on the convex side and uniform cryogenic cooling on the concave side. The finite-element method was used to study the effects of panel curvature and boundary condition on the open-mode stress (radial tensile stress) and displacement fields in the curved sandwich panels. The critical stress point, where potential debonding failure could initiate, was found to be at the midspan (or outer span) of the inner bonding interface between the sandwich core and face sheet on the concave side, depending on the boundary condition and panel curvature. Open-mode stress increases with increasing panel curvature, reaching a maximum value at certain high curvature, and then decreases slightly as the panel curvature continues to increase and approach that of quarter circle. Changing the boundary condition from simply supported to clamped reduces the magnitudes of open-mode stresses and the associated sandwich core depth stretching.

  4. Development of an innovative sandwich common bulkhead for cryogenic upper stage propellant tank

    NASA Astrophysics Data System (ADS)

    Szelinski, B.; Lange, H.; Rttger, C.; Sacher, H.; Weiland, S.; Zell, D.

    2012-12-01

    In the frame of the Future Launcher Preparatory Program (FLPP) investigating advancing technologies for the Next Generation of Launchers (NGL) a number of novel key technologies are presently under development for significantly improving vehicle performance in terms of payload capacity and mission versatility. As a respective ESA guided technology development program, Cryogenic Upper Stage Technologies (CUST) has been launched within FLPP that hosts among others the development of a common bulkhead to separate liquid hydrogen from the liquid oxygen compartment. In this context, MT Aerospace proposed an advanced sandwich design concept which is currently in the development phase reaching for TRL4 under MT Aerospace responsibility. Key components of this sandwich common bulkhead are a specific core material, situated in-between two thin aluminum face sheets, and an innovative thermal decoupling element at the equatorial region. The combination of these elements provides excellent thermal insulation capabilities and mechanical performance at a minimum weight, since mechanical and thermal functions are merged in the same component. This improvement is expressed by substantial performance figures of the proposed concept that include high resistance against reverse pressure, an optimized heat leak and minimized mass, involving the sandwich dome structure and the adjacent interface rings. The development of single sub-technologies, all contributing to maturate the sandwich common bulkhead towards the desired technology readiness level (TRL), is described in the context of the given design constraints as well as technical, functional and programmatic requirements, issued from the stage level. This includes the thermal and mechanical characterization of core materials, manufacturing issues as well as non-destructive testing and the thermal and structural analyses and dimensioning of the complete common bulkhead system. Dedicated TRL assessments in the Ariane 5 Mid-life Evolution (A5-ME) program track the progress of these technology developments and analyze their applicability in time for A5-ME. In order to approximate A5-ME concerned preconditions, activities are initiated aiming at harmonization of the available specifications. Hence, a look-out towards a further technology step approaching TRL6 in a subsequent phase is given, briefly addressing topics of full scale manufacture and appropriate thermo-mechanical testing of an entire sandwich common bulkhead.

  5. [Echinococcus granulosus infection in dogs and livestock from Xinjiang production and construction corps].

    PubMed

    Han, Fei; Wang, Bing-Quan; Wang, Li-Jie; Xiong, Jun; Xi, Yi; Wu, Li-Wen; Ma, Fu-Rong; Li, Fan-Ka

    2014-06-01

    The prevalence of Echinococcus granulosus infection in dogs and livestock was investigated in Xinjiang Production and Construction Corps by stratified random sampling. A total of 5 391 dog feces were detected by double antibody sandwich ELISA, and the positive rate of dog coproantigen was 0.69% (37/5 391). The livestock were subjected to necropsy, inspection and palpation. The prevalence of E. granulosus infection in livestock was 3.88% (431/11 122). PMID:25223066

  6. Construction research

    SciTech Connect

    NONE

    1994-12-31

    The papers in this volume report information on fast-track paving, statistically based specifications, bridge rehabilitation, contracts management, and automation in hot in-place asphalt pavement recycling. Hossain and Wojakowski discuss the construction and performance of a fast-track concrete pavement in Kansas. Weed presents the use of composite pay equations as a means of eliminating the confusion and difficulty in administering the acceptance testing of various quality characteristics. He uses an example based on portland cement concrete pavement to illustrate the practicality of this method. Taavoni describes the upgrading and recycling of an 1879 wrought-iron pin connected truss bridge by replacing the pins. Abdul-Malak and Abou-Assaly investigate innovative concepts of contract management to improve the execution of contracts in Lebanon. They present an integrated contract management approach directed toward understanding the interactions, interrelationships, and interdependencies that exist among candidate concepts and strategies. Pagdadis and Ishai discuss the use of automated equipment used for hot in-place asphalt resurfacing and the breakthroughs that have been achieved toward improving this particular site process through real-time data handling.

  7. The mixed sandwich compounds C5H5MC7H7of the first row transition metals: variable hapticity of the seven-membered ring

    Microsoft Academic Search

    Hongyan Wang; Yaoming Xie; Ioan Silaghi-Dumitrescu; R. Bruce King; Henry F. Schaefer III

    2010-01-01

    The mixed sandwich compounds (?-C5H5)M(?-C7H7) (M = Ti, V, Cr) have been known for approximately 50 years. The vanadium derivative (trovacene) has recently been shown to be a useful precursor for the preparation of a variety of paramagnetic sandwich compounds. In this connection the structures of the complete series of the first row transition metal mixed sandwich compounds C5H5MC7H7 (M

  8. Vertically-aligned sandwich nanowires enhance the photoelectrochemical reduction of hydrogen peroxide: Hierarchical formation on carbon nanotubes of cadmium sulfide quantum dots and Prussian blue nanocoatings.

    PubMed

    Gong, Kuanping

    2015-07-01

    We describe a vertically-aligned array of sandwiched nanowires comprising Prussian blue (PB) nanocoating-carbon nanotube (CNT) core-shell structures with CdS particles positioning at the core/shell interface, viz. PB/CdS/CNT. The PB/CdS/CNT electrode thus constructed are noticeable in synchronically harvesting photon-, ionic-, and chemical-energies, respectively, from visible light radiation, K(+) uptaking and releasing, and the reduction of H2O2. In 0.2M K2SO4 aqueous solution, the photoelectrocatalytic reduction of 1.5mM H2O2 at PB/CdS/CNT delivered the current density as high as 1.91mA/cm(2) at reduced overpotential, that is, three times that at the Pt/C. This superb performance is causally linked to the judicious choice of materials and their assembly into defining sandwich nanostructures wherein the three components closely cooperate with each other in the photoelectrocatalytic reduction of H2O2, including photo-induced charge separation in CdS, spontaneous electron injection into PB due to its relatively low Fermi level, and the electrocatalytic reduction of H2O2 by PB via an electrochemical-chemical-electrochemical reaction mechanism. The structural alignment of PB/CdS/CNT ensures the simplest pathway for the mass diffusion and electron shuttle, and a high surface area accessible to the chemical and electrochemical reactions, so as to minimize the concentration- and electrochemical-polarization and thus ensure the fast overall kinetics of the electrode reaction. PMID:25458868

  9. Multiplexed sandwich immunoassays using flow-injection electrochemiluminescence with designed substrate spatial-resolved technique for detection of tumor markers.

    PubMed

    Zhang, Yan; Liu, Weiyan; Ge, Shenguang; Yan, Mei; Wang, Shaowei; Yu, Jinghua; Li, Nianqiang; Song, Xianrang

    2013-03-15

    Convenient sensor array for simultaneous multi-analyte testing was increasingly needed in clinical diagnosis. A novel electrochemiluminescence (ECL) immunosensor array for the sequential detection of multiple tumor markers was developed by site-selectively immobilizing multiple antigens on different electrodes. Disposable indium tin oxide (ITO) glass array was employed as detection platform. With a sandwich-type immunoassay format, the amount of carbon dots coated silica (SiO(2)@C-dots) labeled antibodies increased with the increment of antigens in the samples. The ECL signal from different immunosensors was collected in turn by a photomultiplier (PMT) with the aid of a home-made potential transformer equiped with a home-made multiplexed-switch. Using carcino embryonic antigen (CEA), prostate specific antigen (PSA) and ?-fetoprotein (?-AFP) as model analytes, the proposed immunoassay exhibited excellent precision and sensitivity. For all three analytes, the relative standard deviations (RSDs) for six times detection were lower than 7.1% and the detection limits were in the range of 0.003-0.006 ng mL(-1). The results for real sample analysis demonstrated that the newly constructed immunosensor array provided a rapid, simple, simultaneous multi-analyte immunoassay with high throughput, cost-effective and sufficiently low detection limits for clinical applications. Importantly, the novel individually addressable immunosensor array for multi-analyte immunoassay by introducing the ECL readout mechanism with the aid of the home-made potential transformer and multiplexed-switch could be a useful supplement to commercial assay methods in clinical chemistry. PMID:23062558

  10. Purification of HRSV F protein from a eukaryotic expression vector and establishment of a sandwich ELISA method.

    PubMed

    Bao, Hong; Yu, Ting; Jin, Yufen; Wang, Chune; Li, Yanlei

    2012-07-01

    In order to increase the expression of the fusion (F) protein and lay a foundation for the construction of a genetically engineered vaccine and rapid clinical detection, the F protein of the human respiratory syncytial virus (HRSV) was expressed and purified, and a sandwich enzyme-linked immunosorbent assay (ELISA) method was established. The F1 fragment of the HRSV F protein was amplified following reverse transcription, and was then combined with the vector and transformed into eukaryotic cells. The recombinant protein was induced and purified. The purified protein was used to immunize mice to produce antiserum and establish indirect ELISA. The established method was tested and verified by analyzing 100 samples using gold immunochromatography (GICA). The F1 fragment of the F gene was successfully amplified, the DNA (+) recombinant was selected, and a protein of molecular weight approximately 45,000 was obtained after the induction. The optimal reaction conditions and working concentration of ELISA were determined. The optimal concentration of mice anti-F1 IgG is 3.2 g/ml, the best reaction time of the samples is 70 min at 37 ?C, and the working concentration of the rabbit anti?mouse IgG is 1:6,000. Compared with the GICA method, the sample's positive co-efficient of variation was 3.2-8.6%, and the negative co-efficient of variation was 5.1-8.3%. These were <10%, indicating that the ELISA method was reproducible. The F1 protein can be greatly expressed in transfected eukaryotic cells, and the purified F1 protein has good immunogenicity. The antiserum produced by the purified recombinant protein can be precisely detected using the ELISA detection method described in this study. PMID:22576739

  11. Role of Ca? in folding the tandem ?-sandwich extender domains of a bacterial ice-binding adhesin.

    PubMed

    Guo, Shuaiqi; Garnham, Christopher P; Karunan Partha, Sarathy; Campbell, Robert L; Allingham, John S; Davies, Peter L

    2013-11-01

    A Ca(2+) -dependent 1.5-MDa antifreeze protein present in an Antarctic Gram-negative bacterium, Marinomonas primoryensis (MpAFP), has recently been reassessed as an ice-binding adhesin. The non-ice-binding region II (RII), one of five distinct domains in MpAFP, constitutes ~ 90% of the protein. RII consists of ~ 120 tandem copies of an identical 104-residue sequence. We used the Protein Homology/analogy Recognition Engine server to define the boundaries of a single 104-residue RII construct (RII monomer). CD demonstrated that Ca(2+) is required for RII monomer folding, and that the monomer is fully structured at a Ca(2+) /protein molar ratio of 10 : 1. The crystal structure of the RII monomer was solved to a resolution of 1.35 by single-wavelength anomalous dispersion and molecular replacement methods with Ca(2+) as the heavy atom to obtain phase information. The RII monomer folds as a Ca(2+) -bound immunoglobulin-like ?-sandwich. Ca(2+) ions are coordinated at the interfaces between each RII monomer and its symmetry-related molecules, suggesting that these ions may be involved in the stabilization of the tandemly repeated RII. We hypothesize that > 600 Ca(2+) ions help to rigidify the chain of 104-residue repeats in order to project the ice-binding domain of MpAFP away from the bacterial cell surface. The proposed role of RII is to help the strictly aerobic bacterium bind surface ice in an Antarctic lake for better access to oxygen and nutrients. This work may give insights into other bacterial proteins that resemble MpAFP, especially those of the large repeats-in-toxin family that have been characterized as adhesins exported via the type I secretion pathway. PMID:24024640

  12. A comprehensive assessment of adhesively bonded joints between sandwich composite beams

    NASA Astrophysics Data System (ADS)

    Shahin, Khaled Omar

    Assessment of adhesively bonded joints between sandwich composite beams are presented in this thesis in three parts, each is concerned with a distinct aspect of the joint behaviour. In physical order, these include the deformations of the entire joint assembly, the state of stress in the joint overlap region, and the strain energy release at the crack-tip at the end of the overlap. Analytical models developed in this thesis, however, are not limited in their application to adhesive joint between sandwich beams. In each part of this thesis, the integrity of the proposed analytical models are tested against geometrically non-linear finite element models. In this first part of this thesis, an analytical asymptotic model is presented for the analysis of balanced and unbalanced adhesively bonded joints. The model takes advantage of the asymptotic nature of the adhesive stress functions by eliminating exponentially small terms. Analysis of balanced and unbalanced adhesive joints is greatly simplified with negligible loss in accuracy. Accurate closed-form solutions for both adhesive peel and shear stresses are presented, providing an efficient analysis and design tool and a significant contribution to the literature on unbalanced adhesively bonded joints. In the second part, the asymptotic model is extended to the analysis of strain energy release rates in adhesively bonded joints, using the crack closure concept. Closed-form expressions are presented for various joint types. The shear force and adhesive layer effects are included in the analysis, thus improving on currently available works in the literature. In joints with a long crack and a thin adhesive layer, the asymptotic model is shown to be in good agreement with classical beam theory models. In the third part, deformations in adhesively bonded joints between sandwich beams are studied. Adherends are modeled as cylindrically bent plates on elastic foundations and the overlap section is treated as a single homogenous plate, thus simplifying the analysis procedure without compromising the accuracy of the results. Analysis of deformations in adhesive joints is undertaken primarily to produce estimates of the bending moments and shear forces at the ends of the overlap, which are used as boundary conditions in the asymptotic model. Results indicate that the sandwich core acts to reduce the severity of the edge moments and shear forces at the ends of the overlap. Furthermore, under certain conditions, the model is shown to be in perfect agreement with Goland and Reissner's model for balanced single-lap joints. Adhesively bonded sandwich beams were tested statically and under fatigue to further verify the accuracy of the proposed analytical models and illustrate their applicability. The adhesive fracture toughness envelope was established experimentally to enable comparisons between analytical and experimental results on adhesively bonded sandwich beams. Fracture toughness of the adhesive is shown to be independent of the adhesive layer thickness and crack length.

  13. Monoclonal antibody sandwich immunoassay detection of coproantigen to evaluate the efficacy of treatment in natural ovine fasciolosis.

    PubMed

    Dumnigo, B E; Mezo, M

    1999-04-01

    The monoclonal antibody-based sandwich immunoassay (mAb Sandwich ELISA) was used to evaluate the effectiveness of triclabendazole treatment by the detection of coproantigens in Fasciola hepatica naturally infected sheep. Twelve sheep (2 to 5 years of age) were separated into two groups. The first group (three sheep) remained untreated; the other group (nine sheep) was treated with a single dose of 5% triclabendazole at 10 mg kg-1 of body weight. All but one of the treated group had negative optical density values (OD492) after two weeks of treatment, while seven sheep intermittently shed eggs during the course of the study. In all but one of the treated sheep, no F. hepatica infection; the one positive ELISA in 5th week after treatment according to the mAb Sandwich, had one fluke in the liver. The results of the parasitological examinations, as well as OD492 values obtained by the mAb Sandwich ELISA for the detection of coproantigens are described. The findings at necropsy, of the treated group in comparison to the untreated group are shown. The mAb Sandwich ELISA could be a useful and accurate method with which to monitor the efficacy of flukicides in F. hepatica natural infections. PMID:10208896

  14. A study of sandwich T-joints and composite lap joints

    NASA Astrophysics Data System (ADS)

    Turaga, Umamaheswar V. R. S.

    In this study, new efficient designs for adhesive sandwich T-joint and single-lap joint were proposed and investigated. In the proposed new sandwich T-joint, called U-channel joint, the load transfer path at the web-flange interface was modified to include a U-shaped aluminum channel which provides strong path for load transfer. Experimental results show that the new design has 62% more strength than the conventional circular fillet joint. The new U-channel joint was tested in tension, compression and bending to investigate its characteristics. It is found to have good performance in bending also, even though in compression it performs same as the circular fillet joint. An extensive parametric study was carried out to investigate the effect of parameters like flange skin stiffener, foam density, foam thickness in the web, and aluminum attachments. A fracture mechanics criterion based on the strain energy release rate was used to explain the failure modes, apart from the stress analysis explanation. The failure loads of the joints in compression were predicted using a maximum principal stress failure criterion based on the sandwich beam theory. A new single lap joint with attachments was proposed in the second phase of the research. The design was verified using both aluminum and composite materials. The new design was found to have 59% more strength than the single-lap joint. A parametric study was performed to find out the influence of the angle of attachment, thickness of attachment and the length of attachment. By careful consideration of design parameters, the joint can be optimized. Finally, the failure loads of the single lap joints with and without attachments were predicted using different failure criteria.

  15. Functional expression and regulation of drug transporters in monolayer- and sandwich-cultured mouse hepatocytes.

    PubMed

    Noel, Gregory; Le Vee, Marc; Moreau, Amlie; Stieger, Bruno; Parmentier, Yannick; Fardel, Olivier

    2013-04-11

    Primary hepatocyte cultures are now considered as convenient models for in vitro analyzing liver drug transport. However, if primary human and rat hepatocytes have been well-characterized with respect to drug transporter expression and regulation, much less is known for primary mouse hepatocytes. The present study was therefore designed to gain insights about this point. The profile of sinusoidal and canalicular drug transporter mRNA expression in short time (4h)-cultured mouse hepatocytes was found to be highly correlated with that of freshly isolated hepatocytes; by contrast, those of counterparts cultured for a longer time (until 4 days) either in monolayer configurations on plastic or collagen or in sandwich configuration with matrigel were profoundly altered: uptake drug transporters such as Oct1, Oatps and Oat2 were thus down-regulated, whereas most of efflux transporters such as Mdr1a/b, Mrp3, Mrp4 and Bcrp were induced. Moreover, short time-cultured hepatocytes exhibited the highest levels of sinusoidal influx transporter activities. Transporter-mediated drug secretion into canalicular networks was however only observed in sandwich-cultured hepatocytes. Mouse hepatocytes cultured either in monolayer or sandwich configurations were finally shown to exhibit up-regulation of referent transporters in response to exposure to prototypical activators of the drug sensing receptors pregnane X receptor, aryl hydrocarbon receptor or constitutive androstane receptor. Taken together, these data demonstrate the feasibility of using primary mouse hepatocytes for investigating potential interactions of xenobiotics with hepatic transporter activity or regulation, provided that adequate culture conditions are retained. PMID:23396053

  16. Interdiffusion and surface-sandwich ordering in initial Ni-core-Pd-shell nanoparticle.

    PubMed

    Evteev, Alexander V; Levchenko, Elena V; Belova, Irina V; Murch, Graeme E

    2009-05-01

    Using molecular dynamics simulation ( approximately 1 mus) in combination with the embedded atom method we have investigated interdiffusion and structural transformations at 1000 K in an initial core-shell nanoparticle (diameter approximately 4.5 nm). This starting particle has the f.c.c. structure in which a core of Ni atoms ( approximately 34%) is surrounded by a shell of Pd atoms ( approximately 66%). It is found that in such nanoparticles reactive diffusion accompanying nucleation and growth of a Pd(2)Ni ordering surface-sandwich structure takes place. In this structure, the Ni atoms mostly accumulate in a layer just below the surface and, at the same time, are located in the centres of interpenetrating icosahedra to generate a subsurface shell as a Kagom net. Meanwhile, the Pd atoms occupy the vertices of the icosahedra and cover this Ni layer from the inside and outside as well as being located in the core of the nanoparticle forming (according to the alloy composition) a Pd-rich solid solution with the remaining Ni atoms. The total atomic fraction involved in building up the surface-sandwich shell of the nanoparticle in the form of the Ni Kagom net layer covered on both side by Pd atoms is estimated at approximately 70%. These findings open up a range of opportunities for the experimental synthesis and study of new kinds of Pd-Ni nanostructures exhibiting Pd(2)Ni surface-sandwich ordering along with properties that may differ significantly from the corresponding bulk Pd-Ni alloys. Some of these opportunities are discussed. PMID:19370219

  17. Compression After Impact Experiments and Analysis on Honeycomb Core Sandwich Panels with Thin Facesheets

    NASA Technical Reports Server (NTRS)

    McQuigg, Thomas D.

    2011-01-01

    A better understanding of the effect of impact damage on composite structures is necessary to give the engineer an ability to design safe, efficient structures. Current composite structures suffer severe strength reduction under compressive loading conditions, due to even light damage, such as from low velocity impact. A review is undertaken to access the current state-of-development in the areas of experimental testing, and analysis methods. A set of experiments on honeycomb core sandwich panels, with thin woven fiberglass cloth facesheets, is described, which includes detailed instrumentation and unique observation techniques.

  18. Enzyme-linked sandwich immunoassay for insulin using laser fluorimetric detection.

    PubMed Central

    Lidofsky, S D; Hinsberg, W D; Zare, R N

    1981-01-01

    Human serum samples are assayed for insulin by an enzyme-linked sandwich immunoassay. Horseradish peroxidase is used as an enzyme label for antibody, and enzyme activity is measured by means of the fluorogenic substrate, p-hydroxyphenylacetic acid. The product is detected by excitation of fluorescence with the 325-nm line of a continuous-wave helium/cadmium ion laser on line with reverse-phase high-pressure liquid chromatography. The incubation period is 90 min and the limit of detection of insulin is 30 pM, corresponding to 5 microunits/ml. This method correlates highly with radioimmunoassay, with coefficient of correlation r = 0.95. PMID:7015349

  19. The Effect of Temperature on Faceplate/Core Delamination in Composite/Titanium Sandwich Plates

    NASA Technical Reports Server (NTRS)

    Liechti, Kenneth M.; Marton, Balazs

    2000-01-01

    A study was made of the delamination behavior of sandwich beams made of titanium core bonded to face-plates that consisted of carbon fiber reinforced polymer composite. Nominally mode I behavior was considered at 23C and 180C, by making use of a specially reinforced double cantilever (DCB) specimens. The toughness of the bond between the faceplate and the core was determined on the basis of a beam on elastic foundation analysis. The specimen compliance, and toughness were all independent of temperature in these relatively short-term experiments. The fracture mechanism showed temperature dependence, due to the hygrothermal sensitivity of the adhesive.

  20. Multi-channeled filtering properties of the sandwich structures composed of epsilon-negative metamaterials

    NASA Astrophysics Data System (ADS)

    Liu, Yan-Hong; He, Li; Dong, Li-Juan; Liu, Li-Xiang; Shi, Yun-Long; Yang, Cheng-Quan

    2013-08-01

    Multi-channeled filtering properties are found in the sandwich structure composed of two ?-negative layers with dielectric permittivity described by Drude model separated by another normal material layer. Epsilon-negative metamaterials are successfully realized by using composite right/left-handed transmission line, based on which the Fabry-Perot (FP) cavity was also constituted. The single resonant mode is split into some discrete resonant peaks, leading to the multi-channeled filtering phenomenon through the several coupled FP cavity resonators. In comparison with the conventional multichanneled filters, the proposed structure is more compact and tunable. The microwave experiment results are found in agreement with simulation results.

  1. A novel sandwich enzyme-linked immunosorbent assay for feline insulin.

    PubMed

    Nakaya, Mariko; Kito, Yuko; Matsuki, Naoaki; Shibata, Haruki; Touhata, Yuki; Tamahara, Satoshi; Ono, Kenichiro

    2009-07-01

    A novel sandwich enzyme-linked immunosorbent assay (ELISA) was established to determine the serum insulin concentrations in domestic cats. By using a solid-phase mouse anti-bovine insulin monoclonal antibody and a peroxidase-conjugated guinea pig anti-rat insulin polyclonal antibody, feline serum insulin concentrations in the range of 0.1 to 3.6 ng/ml could be measured. The intraassay CV and interassay CV were less than 6% and less than 10%, respectively. The present insulin assay will strongly help studies on feline diabetes mellitus. PMID:19652495

  2. The use of ANSYS to calculate the behaviour of sandwich structures

    E-print Network

    Manet, Vincent

    2012-01-01

    In this article, we use different models to compute displacements and stresses of a simply supported sandwich beam subjected to a uniform pressure. 8-node quadrilateral elements (Plane 82), multi-layered 8-node quadrilateral shell elements (Shell 91) and multi-layered 20-node cubic elements (Solid 46) are used. The influence of mesh refinement and of the ratio of Young's moduli of the layers are studied. Finally, a local Reissner method is presented and assessed, which permits an improvement in the accuracy of interface stresses for a high ratio of Young's moduli of the layers with Plane 82 elements.

  3. Proton radiography of PBX 9502 detonation shock dynamics confinement sandwich test

    SciTech Connect

    Aslam, Tariq D [Los Alamos National Laboratory; Jackson, Scott I [Los Alamos National Laboratory; Morris, John S [Los Alamos National Laboratory

    2009-01-01

    Recent results utilizing proton radiography (P-Rad) during the detonation of the high explosive PBX 9502 are presented. Specifically, the effects of confinement of the detonation are examined in the LANL detonation confinement sandwich geometry. The resulting detonation velocity and detonation shock shape are measured. In addition, proton radiography allows one to image the reflected shocks through the detonation products. Comparisons are made with detonation shock dynamics (DSD) and reactive flow models for the lead detonation shock and detonation velocity. In addition, predictions of reflected shocks are made with the reactive flow models.

  4. Low-energy impact resistance of graphite-epoxy plates and ALS honeycomb sandwich panels

    NASA Technical Reports Server (NTRS)

    Hui, David

    1989-01-01

    Low energy impact may be potentially dangerous for many highly optimized stiff structures. Impact by foreign objects such as birds, ice, and runways stones or dropping of tools occur frequently and the resulting damage and stress concentrations may be unacceptable from a designer's standpoint. The barely visible, yet potentially dangerous dents due to impact of foreign objects on the Advanced Launch System (ALS) structure are studied. Of particular interest is the computation of the maximum peak impact force for a given impactor mass and initial velocity. The theoretical impact forces will be compared with the experimental dropweight results for the ALS face sheets alone as well as the ALS honeycomb sandwich panels.

  5. High heat flux actively cooled honeycomb sandwich structural panel for a hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Koch, L. C.; Pagel, L. L.

    1978-01-01

    The results of a program to design and fabricate an unshielded actively cooled structural panel for a hypersonic aircraft are presented. The design is an all-aluminum honeycomb sandwich with embedded cooling passages soldered to the inside of the outer moldline skin. The overall finding is that an actively cooled structure appears feasible for application on a hypersonic aircraft, but the fabrication process is complex and some material and manufacturing technology developments are required. Results from the program are summarized and supporting details are presented.

  6. Employment of a metal microgrid as a front electrode in a sandwich-structured photodetector.

    PubMed

    Zhang, Junying; Cai, Chao; Pan, Feng; Hao, Weichang; Zhang, Weiwei; Wang, Tianmin

    2009-07-01

    A highly UV-transparent metal microgrid was prepared and employed as the front electrode in a sandwich-structured ultraviolet (UV) photodetector using TiO(2) thin film as the semiconductor layer. The photo-generated charger carriers travel a shorter distance before reaching the electrodes in comparison with a photodetector using large-spaced interdigitated metal electrodes (where distance between fingers is several to tens of micrometers) on the surface of the semiconductor film. This photodetector responds to UV light irradiation, and the photocurrent intensity increases linearly with the irradiation intensity below 0.2 mW/cm(2). PMID:19571918

  7. Effect Of Temperature on the Sensitivity of Sandwich Enzyme Immunoassay with Fab'Horseradish Peroxidase Conjugate

    Microsoft Academic Search

    Masayoshi Imagawa; Shinji Yoshitake; Seiichi Hashida; Eiji Ishikawa

    1982-01-01

    Effect of temperature was examined on the sensitivity of sandwich enzyme immunoassay for human chorionic gonadotropin (hCC) with anti-hCG Fab'-horseradish peroxidase conjugates prepared by using three different reagents (N-succinimidyl 4-(N-maleimidomethyl) cyclohexane-l-carboxylate, glutaraldehyde and metaperiodate). The non-specific bindings of the conjugates to anti-hCC IgG-coated polystyrene balls were much lower at 20C than at 37C, and the specific bindings were slightly higher

  8. Engineering of betabellin 15D: Copper(II)-induced folding of a fibrillar ?-sandwich protein

    Microsoft Academic Search

    Amareth Lim; Philippe A. Guy; Alexander M. Makhov; Matthew J. Saderholm; Mathias Kroll; Yibing Yan; Robert J. Anderegg; Jack D. Griffith; Bruce W. Erickson

    1999-01-01

    SummaryThe inverse protein-folding problem has been explored by designing de novo the betabellin target structure (a 64-residue ?-sandwich\\u000a protein), synthesizing a 32-residue peptide chain (HSLTAKIpkLTFSIAphTYTCAVpkYTAKVSH, wherep=DPro,k=DLys, andh=DHis) that might fold into this structure, and studying how its disulfide-bridged form (betabellin 15D) folds in 10 mM ammonium\\u000a acetate with and without Cu2+. Circular dichroic spectropolarimetry indicated that at pH 5.8, 6.4,

  9. Application of Air Coupled Acoustic Thermography (ACAT) for Inspection of Honeycomb Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Winfree, William P.; Zalameda, Joseph N.; Pergantis, Charles; Flanagan, David; Deschepper, Daniel

    2009-01-01

    The application of a noncontact air coupled acoustic heating technique is investigated for the inspection of advanced honeycomb composite structures. A weakness in the out of plane stiffness of the structure, caused by a delamination or core damage, allows for the coupling of acoustic energy and thus this area will have a higher temperature than the surrounding area. Air coupled acoustic thermography (ACAT) measurements were made on composite sandwich structures with damage and were compared to conventional flash thermography. A vibrating plate model is presented to predict the optimal acoustic source frequency. Improvements to the measurement technique are also discussed.

  10. Constructing Aligned Assessments Using Automated Test Construction

    ERIC Educational Resources Information Center

    Porter, Andrew; Polikoff, Morgan S.; Barghaus, Katherine M.; Yang, Rui

    2013-01-01

    We describe an innovative automated test construction algorithm for building aligned achievement tests. By incorporating the algorithm into the test construction process, along with other test construction procedures for building reliable and unbiased assessments, the result is much more valid tests than result from current test construction

  11. APPLICATION CONSTRUCTION LEADERSHIP COURSE

    E-print Network

    Stephens, Graeme L.

    in the construction industry 5) If your GPA . Include experience in construction industry. Recommendation from an Instructor Provide instructorAPPLICATION CONSTRUCTION LEADERSHIP COURSE RECOMMENDATION FORM CON464 Construction Leadership

  12. English airplane construction

    NASA Technical Reports Server (NTRS)

    Schwencke, D

    1930-01-01

    English airplane construction is presented with a particular emphasis on metal construction techniques. Steel rib and fuselage construction are discussed as well as the use of duralumin in construction.

  13. A study of vacuum evaporated Al/Cds/Al thin film sandwich structure as capacitive type temperature transducer

    NASA Astrophysics Data System (ADS)

    Iyyer, S. B.; Sayyed, S. A.; Bhand, G. R.

    2012-06-01

    Vacuum evaporated thin films of CdS were sandwiched between vacuum evaporated aluminum (Al) films on a glass substrate at room temperature at a vacuum of 10-5 Torr. The vacuum had to be broken after every successive coating. Thin film of Al/CdS/Al sandwich structure shows capacitance value in the range of 15 to 25nF. The structure shows variation of capacitance with temperature. The study of current-voltage characteristics of these structures shows rectifying behavior for both polarities of applied bias voltages. These studies lead to the fact that vacuum evaporated thin film of Al/CdS/Al sandwich structure has potential application as capacitive type temperature transducer.

  14. Localised Effects in Sandwich Structures with Internal Core Junctions:Modelling and Experimental Characterisation of Load Response, Failure and Fatigue

    NASA Astrophysics Data System (ADS)

    Johannes, Martin; Thomsen, Ole Thybo

    The objective is to provide an overview of the mechanisms which determine the occurrence and severity of localized bending effects in sandwich structures. It is known from analytical and numerical modelling that local effects lead to an increase of the face bending stresses as well as the core shear and transverse normal stresses. The modelling and experimental characterisation of local effects in sandwich structures will be addressed based on the simple and generic case of sandwich structures with internal core junctions under general shear, bending and in-plane loading conditions. The issue of failure and fatigue phenomena induced by the presence of core junctions will be discussed in detail, with the inclusion of recent theoretical and experimental results.

  15. Fire sandwich

    NSDL National Science Digital Library

    Mid-continent Research for Education and Learning (McREL)

    2004-01-01

    This activity about heat and combustion was designed to engage students in thinking about the scientific principles involved in a teacher demonstration. In the demonstration, the teacher positions wire screens at different locations over a Bunsen burner, thereby altering the location of the flame. Questions are included for teachers to ask students during the demonstration. The activity lists procedural and safety notes, required materials, and related national science education standards and science process skills. In addition, the science content is explained. This activity is one part of the Whelmers set of activities, which was created to capture students' interest in science.

  16. Seepy Sandwich

    NSDL National Science Digital Library

    Joe Pitts

    This activity is designed to demonstrate how water infiltration can carry pollution underground. The activity shows how pollutants are carried by water, that pollutants are not filtered out by the ground, and that human activities can affect groundwater quality.

  17. Static, Vibration and Buckling Analysis of Skew Composite and Sandwich Plates Under Thermo Mechanical Loading

    NASA Astrophysics Data System (ADS)

    Singh, S. K.; Chakrabarti, A.

    2013-08-01

    Static, vibration and buckling behavior of laminated composite and sandwich skew plates is studied using an efficient C0 FE model developed based on refined higher order zigzag theory. The C0 FE model satisfies the interlaminar shear stress continuity at the interfaces and zero transverse shear stress conditions at plate top and bottom. In this model, the first derivatives of transverse displacement have been treated as independent variables to overcome the problem of C1 continuity associated with the plate theory. The C0 continuity of the present element is compensated in the stiffness matrix formulation by adding a suitable term. In order to avoid stress oscillations observed in the displacement based finite element, the stress field derived from temperature is made consistent with the total strain field by using field consistent approach. Numerical results are presented for different static, vibration and buckling problems by applying the FE model under thermo mechanical loading, where a nine noded C0 continuous isoparametric element is used. It is observed that there are very few results available in the literature on laminated composite and sandwich skew plates based on refined theories. As such many new results are also generated for future reference

  18. Compression After Impact on Honeycomb Core Sandwich Panels With Thin Facesheets. Part 1; Experiments

    NASA Technical Reports Server (NTRS)

    McQuigg, Thomas D.; Kapania, Rakesh K.; Scotti, Stephen J.; Walker, Sandra P.

    2012-01-01

    A two part research study has been completed on the topic of compression after impact (CAI) of thin facesheet honeycomb core sandwich panels. The research has focused on both experiments and analysis in an effort to establish and validate a new understanding of the damage tolerance of these materials. Part one, the subject of the current paper, is focused on the experimental testing. Of interest are sandwich panels, with aerospace applications, which consist of very thin, woven S2-fiberglass (with MTM45-1 epoxy) facesheets adhered to a Nomex honeycomb core. Two sets of specimens, which were identical with the exception of the density of the honeycomb core, were tested. Static indentation and low velocity impact using a drop tower are used to study damage formation in these materials. A series of highly instrumented CAI tests was then completed. New techniques used to observe CAI response and failure include high speed video photography, as well as digital image correlation (DIC) for full-field deformation measurement. Two CAI failure modes, indentation propagation, and crack propagation, were observed. From the results, it can be concluded that the CAI failure mode of these panels depends solely on the honeycomb core density.

  19. Shape and Stress Sensing of Multilayered Composite and Sandwich Structures Using an Inverse Finite Element Method

    NASA Technical Reports Server (NTRS)

    Cerracchio, Priscilla; Gherlone, Marco; Di Sciuva, Marco; Tessler, Alexander

    2013-01-01

    The marked increase in the use of composite and sandwich material systems in aerospace, civil, and marine structures leads to the need for integrated Structural Health Management systems. A key capability to enable such systems is the real-time reconstruction of structural deformations, stresses, and failure criteria that are inferred from in-situ, discrete-location strain measurements. This technology is commonly referred to as shape- and stress-sensing. Presented herein is a computationally efficient shape- and stress-sensing methodology that is ideally suited for applications to laminated composite and sandwich structures. The new approach employs the inverse Finite Element Method (iFEM) as a general framework and the Refined Zigzag Theory (RZT) as the underlying plate theory. A three-node inverse plate finite element is formulated. The element formulation enables robust and efficient modeling of plate structures instrumented with strain sensors that have arbitrary positions. The methodology leads to a set of linear algebraic equations that are solved efficiently for the unknown nodal displacements. These displacements are then used at the finite element level to compute full-field strains, stresses, and failure criteria that are in turn used to assess structural integrity. Numerical results for multilayered, highly heterogeneous laminates demonstrate the unique capability of this new formulation for shape- and stress-sensing.

  20. Dynamic Response and Optimal Design of Curved Metallic Sandwich Panels under Blast Loading

    PubMed Central

    Yang, Shu; Han, Shou-Hong; Lu, Zhen-Hua

    2014-01-01

    It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA) steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a soft outer face and a hard inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD) and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA) and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN) metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances. PMID:25126606

  1. Elevated Temperature, Residual Compressive Strength of Impact-Damaged Sandwich Structure Manufactured Out-of-Autoclave

    NASA Technical Reports Server (NTRS)

    Grimsley, Brian W.; Sutter, James K.; Burke, Eric R.; Dixon, Genevieve D.; Gyekenyesi, Thomas G.; Smeltzer, Stanley S.

    2012-01-01

    Several 1/16th-scale curved sandwich composite panel sections of a 10 m diameter barrel were fabricated to demonstrate the manufacturability of large-scale curved sections using minimum gauge, [+60/-60/0]s, toughened epoxy composite facesheets co-cured with low density (50 kilograms per cubic meters) aluminum honeycomb core. One of these panels was fabricated out of autoclave (OoA) by the vacuum bag oven (VBO) process using Cycom(Registered Trademark) T40-800b/5320-1 prepreg system while another panel with the same lay-up and dimensions was fabricated using the autoclave-cure, toughened epoxy prepreg system Cycom(Registered Trademark) IM7/977-3. The resulting 2.44 m x 2 m curved panels were investigated by non-destructive evaluation (NDE) at NASA Langley Research Center (NASA LaRC) to determine initial fabrication quality and then cut into smaller coupons for elevated temperature wet (ETW) mechanical property characterization. Mechanical property characterization of the sandwich coupons was conducted including edge-wise compression (EWC), and compression-after-impact (CAI) at conditions ranging from 25 C/dry to 150 C/wet. The details and results of this characterization effort are presented in this paper.

  2. Development of sandwich-form biosensor to detect Mycobacterium tuberculosis complex in clinical sputum specimens.

    PubMed

    Shojaei, Taha Roodbar; Mohd Salleh, Mohamad Amran; Tabatabaei, Meisam; Ekrami, Alireza; Motallebi, Roya; Rahmani-Cherati, Tavoos; Hajalilou, Abdollah; Jorfi, Raheleh

    2014-01-01

    Mycobacterium tuberculosis, the causing agent of tuberculosis, comes second only after HIV on the list of infectious agents slaughtering many worldwide. Due to the limitations behind the conventional detection methods, it is therefore critical to develop new sensitive sensing systems capable of quick detection of the infectious agent. In the present study, the surface modified cadmium-telluride quantum dots and gold nanoparticles conjunct with two specific oligonucleotides against early secretory antigenic target 6 were used to develop a sandwich-form fluorescence resonance energy transfer-based biosensor to detect M. tuberculosis complex and differentiate M. tuberculosis and M. bovis Bacille Calmette-Guerin simultaneously. The sensitivity and specificity of the newly developed biosensor were 94.2% and 86.6%, respectively, while the sensitivity and specificity of polymerase chain reaction and nested polymerase chain reaction were considerably lower, 74.2%, 73.3% and 82.8%, 80%, respectively. The detection limits of the sandwich-form fluorescence resonance energy transfer-based biosensor were far lower (10 fg) than those of the polymerase chain reaction and nested polymerase chain reaction (100 fg). Although the cost of the developed nanobiosensor was slightly higher than those of the polymerase chain reaction-based techniques, its unique advantages in terms of turnaround time, higher sensitivity and specificity, as well as a 10-fold lower detection limit would clearly recommend this test as a more appropriate and cost-effective tool for large scale operations. PMID:25181404

  3. Propagation of Longitudinal Waves in Microporous Slab Sandwiched between Elastic Half-Spaces

    NASA Astrophysics Data System (ADS)

    Hsia, Shao-Yi; Su, Chih-Chun

    2008-07-01

    A granular composite that consists of stiff inclusions embedded in a weaker matrix produces a well defined micro-structure. This composite is extensively used in the passive noise control field in sound absorbers. In classical continuum mechanics, the basic assumption is that the micro-structure of a material does not govern the mechanical behavior. However, classical theory and experimental results have some discrepancies, revealing the potential importance of the micro-structure. For instance, acoustic waves are characterized by high frequencies and small wavelengths, particularly in microporous materials with various stiffness values. Consequently, unlike for a homogeneous isotropic elastic medium with only two elastic constants, linear elastic micropolar theory utilizes 6 degrees of freedom and its results can hence be regarded as being a function of the micro-structure. This investigation explores the reflected and transmitted wave fields of an incident longitudinal plane wave that propagates in elastic-microporous-elastic interfaces. The numerical study demonstrates a through transmission in the sandwiched problem in situation of interest. This property of the half-wave microporous layer allows it to be regarded as a frequency or direction filter. Two sets of the forward and backward transverse plane waves are present in the sandwiched microporous layer. The specified work frequency and the width of the intermediate microporous layer affect all of the described phenomena.

  4. Sandwich beam model for free vibration analysis of bilayer graphene nanoribbons with interlayer shear effect

    NASA Astrophysics Data System (ADS)

    Nazemnezhad, Reza; Shokrollahi, Hassan; Hosseini-Hashemi, Shahrokh

    2014-05-01

    In this study, sandwich beam model (SM) is proposed for free vibration analysis of bilayer graphene nanoribbons (BLGNRs) with interlayer shear effect. This model also takes into account the intralayer (in-plane) stretch of graphene nanoribbons. The molecular dynamics (MD) simulations using the software LAMMPS and Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential are done to validate the accuracy of the sandwich model results. The MD simulation results include the two first frequencies of cantilever BLGNRs with different lengths and two interlayer shear moduli, i.e., 0.25 and 4.6 GPa. These two interlayer shear moduli, 0.25 and 4.6 GPa, can be obtained by sliding a small flake of graphene on a large graphene substrate when the parameter of E_LJ term in AIREBO potential, epsilon_CC, is set to be 2.84 and 45.44 meV, respectively. The SM results for a wide range of bending rigidity values show that the proposed model, i.e., the SM, predicts much better than the previous beam model in which the intralayer stretch is ignored. In addition, it is observed that the model can properly predict the natural frequencies of BLGNRs for various values of the bending rigidity and the interlayer shear modulus.

  5. Preparation and microwave absorption properties of foam-based honeycomb sandwich structures

    NASA Astrophysics Data System (ADS)

    He, Yanfei; Gong, Rongzhou

    2009-03-01

    Radar-absorbing structures having foam-based honeycomb sandwich structures (FBHSS) were fabricated through a conventional foaming technique. Conductive fillers such as carbonyl iron/nickel fibers (CINF) and magnetic metal micropowder (MMP) were added to polyurethane foams so as to efficiently increase the absorbing capacity of FBHSS. A honeycomb sandwich structure, which was made of composite face sheets and foam cores, was used as a supporter to enhance mechanical strength. A matching layer made of nanotitanium powder and hydrogenation acrylonitrile-butadiene rubber composites was used for the face sheet, which allows the incident electromagnetic wave to enter and largely get attenuated through the absorbing system. Polyurethane foams containing CINFs and MMP of which a suitable content contributing to a broad bandwidth and high loss, were used as the core material. The measurement results show reflection loss was less than -10 dB over the frequency range of 3-18 GHz, which has a minimum value of - 26 dB at 14.2 GHz.

  6. Development of honeycomb sandwich finite element modeling techniques for dynamic and static analysis

    NASA Astrophysics Data System (ADS)

    Spoonire, Ross A.

    2010-07-01

    Honeycomb sandwich core is typically modeled as an equivalent continuum for both static and dynamic analysis. The orthotropic material properties for such a continuum representation are difficult to predict. The objective of this work is to examine material and geometric parameters that affect the elastic and harmonic responses of honeycomb cores. A 3D shell FEA approach is adopted to model the core geometry. The model is compared to a typical homogeneous core finite-element representation in vibratory response. It is found that adhesive filleting can play a significant role in the response of honeycomb sandwich structure. Additionally, finite-element models using homogenized core approximations are shown to yield erroneous predictions for higher modes of vibration. Only through the modeling of actual honeycomb core geometry through finiteelement methods is it possible to predict higher modes. Vibration occurring strictly in the honeycomb cells can be observed by a tight band of resonances. This band occurs at different frequency ranges depending on the modeling technique. Achieving accurate homogeneous core model dynamic response for higher modes is restricted by computational inefficiency. Steady state harmonic analysis was only possible using the 3D shell core representation. The homogeneous core models were accurate in static shear and early modal response only. When it becomes necessary to predict shorter wavelengths of vibration, the homogeneous core models are either too computationally expensive or produce incorrect responses specifically with regard to modes isolated in the core.

  7. Sandwich beam model for free vibration analysis of bilayer graphene nanoribbons with interlayer shear effect

    SciTech Connect

    Nazemnezhad, Reza, E-mail: rnazemnezhad@iust.ac.ir, E-mail: rnazemnezhad@du.ac.ir [School of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Shokrollahi, Hassan [School of Mechanical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Hosseini-Hashemi, Shahrokh [School of Mechanical Engineering, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of); Center of Excellence in Railway Transportation, Iran University of Science and Technology, Narmak, Tehran (Iran, Islamic Republic of)

    2014-05-07

    In this study, sandwich beam model (SM) is proposed for free vibration analysis of bilayer graphene nanoribbons (BLGNRs) with interlayer shear effect. This model also takes into account the intralayer (in-plane) stretch of graphene nanoribbons. The molecular dynamics (MD) simulations using the software LAMMPS and Adaptive Intermolecular Reactive Empirical Bond Order (AIREBO) potential are done to validate the accuracy of the sandwich model results. The MD simulation results include the two first frequencies of cantilever BLGNRs with different lengths and two interlayer shear moduli, i.e., 0.25 and 4.6?GPa. These two interlayer shear moduli, 0.25 and 4.6?GPa, can be obtained by sliding a small flake of graphene on a large graphene substrate when the parameter of E-LJ term in AIREBO potential, epsilon-CC, is set to be 2.84 and 45.44?meV, respectively. The SM results for a wide range of bending rigidity values show that the proposed model, i.e., the SM, predicts much better than the previous beam model in which the intralayer stretch is ignored. In addition, it is observed that the model can properly predict the natural frequencies of BLGNRs for various values of the bending rigidity and the interlayer shear modulus.

  8. Bulk-heterojunction organic solar cells sandwiched by solution processed molybdenum oxide and titania nanosheet layers

    NASA Astrophysics Data System (ADS)

    Itoh, Eiji; Goto, Yoshinori; Fukuda, Katsutoshi

    2014-02-01

    The contributions of ultrathin titania nanosheet (TN) crystallites were studied in both an inverted bulk-heterojunction (BHJ) cell in an indium-tin oxide (ITO)/titania nanosheet (TN)/poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methylester (PCBM) active layer/MoOx/Ag multilayered photovoltaic device and a conventional BHJ cell in ITO/MoOx/P3HT:PCBM active layer/TN/Al multilayered photovoltaic device. The insertion of only one or two layers of poly(diallyldimethylammonium chloride) (PDDA) and TN multilayered film prepared by the layer-by-layer deposition technique effectively decreased the leakage current and increased the open circuit voltage (VOC), fill factor (FF), and power conversion efficiency (?). The conventional cell sandwiched between a solution-processed, partially crystallized molybdenum oxide hole-extracting buffer layer and a TN electron extracting buffer layer showed comparable cell performance to a device sandwiched between vacuum-deposited molybdenum oxide and TN layers, whereas the inverted cell with solution-processed molybdenum oxide showed a poorer performance probably owing to the increment in the leakage current across the film. The abnormal S-shaped curves observed in the inverted BHJ cell above VOC disappeared with the use of a polyfluorene-based cationic semiconducting polymer as a substitute for an insulating PDDA film, resulting in the improved cell performance.

  9. Characteristics of zinc behavior during laser welding of zinc "sandwich" sample

    NASA Astrophysics Data System (ADS)

    Zhang, Yi; Li, Shichun; Chen, Genyu; Zhang, Hairong; Zhang, Mingjun

    2012-11-01

    To address the problem of the zinc being easily gasified in laser welding of galvanized steel, laser welding of a zinc "sandwich" sample was performed to experimentally investigate the behavior and characteristics of the zinc inside and outside the keyhole, including the observation of the keyhole, the zinc vapor and zinc plasma, and the calculation of the electron temperature of the zinc plasma. Based on the principle of imaging amplification, the detected multi-points can be located precisely in order to study the distribution of the electron temperature of the zinc plasma. The results show that the zinc behavior played an important role in the formation of the weld-joint and the zinc plasma altered the energy distribution at the top of the keyhole whose diameter has been enlarged in the welding process. For both continuous-wave laser and pulsed laser welding of zinc "sandwich" sample, the average electron temperature of the zinc keyhole plasma was higher than that of the zinc plasma plume outside the keyhole. In the welding process, the continuous wave laser with higher input energy results in higher position of the zinc plasma with higher electron temperature above the sample surface. More zinc vapor resulted in a higher average electron temperature of the plasma.

  10. Sandwich-Type Functionalized Graphene Sheet-Sulfur Nanocomposite for Rechargeable Lithium Batteries

    SciTech Connect

    Cao, Yuliang; Li, Xiaolin; Aksay, Ilhan A.; Lemmon, John P.; Nie, Zimin; Yang, Zhenguo; Liu, Jun

    2011-03-30

    A sandwich structured graphene sheet-sulfur (GSS) nanocomposite was synthesized as the cathode material for lithium-sulfur batteries. The structure has a layer of graphene stacks and a layer of sulfur nanoparticles integrated into a three-dimensional architecture. This GSS nanoscale layered composite, making use of the efficient physical and electrical contact between sulfur and the large surface area, highly conductive graphene, provides a high loading of active materials of ~70 wt%, a high tape density of ~0.92 g?cm-3, and a high power with a reversible capacity of ~505 mAh?g-1 (~464 mAh?cm-3) at a current density of 1,680 mA?g-1 (1C). When coated with a thin layer of cation exchange Nafion film, the migration of dissolved polysulfide anions from the GSS nanocomposite was effectively alleviated, leading to a good cycling stability of 75% capacity retention over 100 cycles. This sandwich-structured composite conceptually provides a new strategy for designing electrodes in energy storage applications.

  11. Characterization of dermal plates from armored catfish Pterygoplichthys pardalis reveals sandwich-like nanocomposite structure.

    PubMed

    Ebenstein, Donna; Calderon, Carlos; Troncoso, Omar P; Torres, Fernando G

    2015-05-01

    Dermal plates from armored catfish are bony structures that cover their body. In this paper we characterized structural, chemical, and nanomechanical properties of the dermal plates from the Amazonian fish Pterygoplichthys pardalis. Analysis of the morphology of the plates using scanning electron microscopy (SEM) revealed that the dermal plates have a sandwich-like structure composed of an inner porous matrix surrounded by two external dense layers. This is different from the plywood-like laminated structure of elasmoid fish scales but similar to the structure of osteoderms found in the dermal armour of some reptiles and mammals. Chemical analysis performed using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) results revealed similarities between the composition of P. pardalis plates and the elasmoid fish scales of Arapaima gigas. Reduced moduli of P. pardalis plates measured using nanoindentation were also consistent with reported values for A. gigas scales, but further revealed that the dermal plate is an anisotropic and heterogeneous material, similar to many other fish scales and osteoderms. It is postulated that the sandwich-like structure of the dermal plates provides a lightweight and tough protective layer. PMID:25732181

  12. Development of a sandwich enzyme-linked immunosorbent assay to detect and measure serum levels of canine ferritin.

    PubMed

    Chikazawa, Seishiro; Hori, Yasutomo; Hoshi, Fumio; Kanai, Kazutaka; Ito, Naoyuki; Sato, Jun; Orino, Koichi; Watanabe, Kiyotaka; Higuchi, Sei-ichi

    2013-05-01

    We established a homologous sandwich enzyme-linked immunosorbent assay (ELISA) to measure serum levels of canine ferritin. Our assay uses a rabbit anti-canine heart ferritin polyclonal antibody, and canine heart ferritin as a standard. Serum ferritin concentration in healthy dogs (n=163) was 789 284 ng/ml (mean standard deviation), a value higher than reported previously. Confidence levels relating to repeatability, dilution and recovery for this method were high. Therefore, we believe our developed sandwich ELISA will be effective in evaluating serum levels of canine ferritin. PMID:23149482

  13. A sandwich-designed temperature-gradient incubator for studies of microbial temperature responses.

    PubMed

    Elsgaard, Lars; Jrgensen, Leif Wagner

    2002-03-01

    A temperature-gradient incubator (TGI) is described, which produces a thermal gradient over 34 aluminium modules (15x30x5 cm) intersected by 2-mm layers of partly insulating graphite foil (SigraFlex Universal). The new, sandwich-designed TGI has 30 rows of six replicate sample wells for incubation of 28-ml test tubes. An electric plate heats one end of the TGI, and the other end is cooled by thermoelectric Peltier elements in combination with a liquid cooling system. The TGI is equipped with 24 calibrated Pt-100 temperature sensors and insulated by polyurethane plates. A PC-operated SCADA (Supervisory Control And Data Acquisition) software (Genesis 4.20) is applied for temperature control using three advanced control loops. The precision of the TGI temperature measurements was better than +/-0.12 degrees C, and for a 0-40 degrees C gradient, the temperature at the six replicate sample wells varied less than +/-0.04 degrees C. Temperatures measured in incubated water samples closely matched the TGI temperatures, which showed a linear relationship to the sample row number. During operation for 8 days with a gradient of 0-40 degrees C, the temperature at the cold end was stable within +/-0.02 degrees C, while the temperatures at the middle and the warm end were stable within +/-0.08 degrees C (n=2370). Using the new TGI, it was shown that the fine-scale (1 degrees C) temperature dependence of S(o) oxidation rates in agricultural soil (0-29 degrees C) could be described by the Arrhenius relationship. The apparent activation energy (E(a)) for S(o) oxidation was 79 kJ mol(-1), which corresponded to a temperature coefficient (Q(10)) of 3.1. These data demonstrated that oxidation of S(o) in soil is strongly temperature-dependent. In conclusion, the new TGI allowed a detailed study of microbial temperature responses as it produced a precise, stable, and certifiable temperature gradient by the new and combined use of sandwich-design, thermoelectric cooling, and advanced control loops. The sandwich-design alone reduced the disadvantageous thermal gradient over individual sample wells by 56%. PMID:11777580

  14. Exploring Oxidation of Half-Sandwich Rhodium Complexes: Oxygen Atom Insertion into the Rhodium-Carbon Bond of 2

    E-print Network

    Jones, William D.

    Exploring Oxidation of Half-Sandwich Rhodium Complexes: Oxygen Atom Insertion into the Rhodium into the rhodium-carbon bond of coordinated phpy was observed. This resulted in the formation of a 2 2-(2-pyridyl as a neutral, two-electron donor ligand, coordinated to the rhodium center through the iodosyl oxygen. Over

  15. On Thermoelastic and Hygrometric Response of Sandwich Beams with Laminate Facings and Honeycomb Cores: Part IVA Dynamic Theory

    Microsoft Academic Search

    Achintya K. Mukhopadhyay; Robert L. Sierakowski

    2000-01-01

    The systematic development of a dynamic theory for a sandwich beam is presented leading to the governing equations of equilibrium and the natural boundary conditions. Using Timoshenko beam theory [I], a function 1' is introduced in terms of the kinetic and strain energies of the system consisting of both laminate facings and honeycomb core. Reissner's variational theorem is used in

  16. Magnetoconductivity and magnetoluminescence studies in bipolar and almost hole-only sandwich devices made from films of a ?-conjugated molecule

    Microsoft Academic Search

    Tho Duc Nguyen; Yugang Sheng; James E Rybicki; Markus Wohlgenannt

    2008-01-01

    We present magnetoconductivity and magnetoluminescence measurements in sandwich devices made from films of a ?-conjugated molecule and demonstrate effects of more than 30 and 50% magnitude, respectively, in fields of 100 mT at room-temperature. It has previously been recognized that the effect is caused by hyperfine coupling, and that it is phenomenologically similar to other magnetic field effects that act

  17. Materials Science and Engineering A 472 (2008) 242250 Shear behavior of aluminum lattice truss sandwich panel structures

    E-print Network

    Wadley, Haydn

    2008-01-01

    Materials Science and Engineering A 472 (2008) 242250 Shear behavior of aluminum lattice truss of Materials Science and Engineering, University of Virginia, 140 Chemistry Way, Charlottesville, VI 22904, USA hardenable 6061 aluminum tetrahedral lattice truss core sandwich panels have been fabricated by folding

  18. The Role of Sandwich In-Service Program in Developing Agricultural Science Teachers in Delta State, Nigeria

    ERIC Educational Resources Information Center

    Ikeoji, Canice N.; Agwubike, Christian C.; Ideh, Victor

    2007-01-01

    This study examined the role of the sandwich in-service educational program of Delta State University, Abraka in developing agricultural science teachers in the state. Data were collected from 895 agricultural science teachers who completed the program between 1989-2004. However, response to the questionnaire was by 391 in-service agricultural

  19. Experimental, Theoretical and Numerical Investigation of the Flexural Behaviour of the Composite Sandwich Panels with PVC Foam Core

    NASA Astrophysics Data System (ADS)

    Mostafa, A.; Shankar, K.; Morozov, E. V.

    2014-08-01

    This study presents the main results of an experimental, theoretical and numerical investigation on the flexural behaviour and failure mode of composite sandwich panels primarily developed for marine applications. The face sheets of the sandwich panels are made up of glass fibre reinforced polymer (GFRP), while polyvinylchloride (PVC) foam was used as core material. Four-point bending test was carried out to investigate the flexural behaviour of the sandwich panel under quasi static load. The finite element (FE) analysis taking into account the cohesive nature of the skin-core interaction as well as the geometry and materials nonlinearity was performed, while a classical beam theory was used to estimate the flexural response. Although the FE results accurately represented the initial and post yield flexural response, the theoretical one restricted to the initial response of the sandwich panel due to the linearity assumptions. Core shear failure associate with skin-core debonding close to the loading points was the dominant failure mode observed experimentally and validated numerically and theoretically.

  20. Photoelastic stress analysis of skewed cutout in a sandwich skew plate subjected to inplane and transverse eccentric load

    Microsoft Academic Search

    K. Lingaiah; S. T. Murthy

    1991-01-01

    Results are presented of a photoelastic study of skew plates commonly employed in machine members and structures such as parts of airplane wings, missiles, ship decks and floor slabs of skew bridges and buildings. The investigation involved skew sandwich plates made of Araldite varying in width from 80 mm to 40 mm and skew angle varying from 0 to 40

  1. Open-Die Forging of Structurally Porous Sandwich Panels D.M. ELZEY and H.N.G. WADLEY

    E-print Network

    Wadley, Haydn

    distribution via subsequent thermomechanical forming. A plane-strain solution for analyzing the open response is used in a classical "slab" analysis of open-die forging. The analysis predicts the upsetting a modified form of a slab analysis to investi- One approach to titanium sandwich panel manufacture is gate

  2. International Journal of Impact Engineering 35 (2008) 920936 Impact response of sandwich plates with a pyramidal lattice core

    E-print Network

    Wadley, Haydn

    2008-01-01

    with a pyramidal lattice core Christian J. Yungwirtha , Haydn N.G. Wadleya , John H. O'Connorb , Alan J. Zakraysekb . The sandwich plates comprised two identical face sheets and a pyramidal truss core: the diameter performance. r 2007 Elsevier Ltd. All rights reserved. Keywords: Impact; Pyramidal truss; Air shock waves

  3. Multi-physics modeling of the fabrication and dynamic performance of all-metal auxetic-hexagonal sandwich-structures

    E-print Network

    Grujicic, Mica

    work include: (a) sheet-metal fabrication using cold flat rolling; (b) a simple stamping process used to investigate the effect of the prior processing and the resulting microstructure on the performance of all-metal sandwich-structures with an auxetic-hexagonal core. Specific fabrication processes analyzed in the present

  4. Experimental investigation of the collapse modes and the main crushing characteristics of composite sandwich panels subjected to flexural loading

    Microsoft Academic Search

    A. G. Mamalis; K. N. Spentzas; D. E. Manolakos; M. B. Ioannidis; D. P. Papapostolou

    2008-01-01

    The flexural properties, collapse modes and crushing characteristics of various types of composite sandwich panels that were candidate materials for the manufacture of the front-end bumper of transportation vehicles were investigated in a series of three-point bending tests that were performed in accordance with the American Society for Testing and Materials International Standard D790. The tested hybrid composites

  5. PAPER www.rsc.org/obc | Organic & Biomolecular Chemistry Ruthenium half-sandwich complexes as protein kinase inhibitors

    E-print Network

    Meggers, Eric

    PAPER www.rsc.org/obc | Organic & Biomolecular Chemistry Ruthenium half-sandwich complexes on the web 20th March 2007 DOI: 10.1039/b700433h A general route to ruthenium pyridocarbazole half is replaced by a ruthenium fragment. Although structurally related, these new scaffolds turned out to possess

  6. Creep Expansion of Porous Ti-6Al-4V Sandwich Structures DOUGLAS T. QUEHEILLALT, BILL W. CHOI, DANIEL S. SCHWARTZ,

    E-print Network

    Wadley, Haydn

    Creep Expansion of Porous Ti-6Al-4V Sandwich Structures DOUGLAS T. QUEHEILLALT, BILL W. CHOI of a porous core and fully dense face sheets can be produced by consolidating argon gas charged powder of the two sensors was found to enable the in situ determination of both the porous cores relative density

  7. Identification of elastic and damping properties of sandwich structures based on high resolution modal analysis of point

    E-print Network

    Paris-Sud XI, Université de

    and dampings of the natural modes of the panel are estimated experimentally by means of a high-resolution modal characteristics (for example modal damp- ings Num n vs. XP n and frequencies f Num n vs. f XP n of the first modesIdentification of elastic and damping properties of sandwich structures based on high resolution

  8. Damage monitoring in sandwich beams by modal parameter shifts: A comparative study of burst random and sine dwell

    E-print Network

    Mailhes, Corinne

    effect on the modal parameters and also proved that sine dwell testing is more suitable for damping1 Damage monitoring in sandwich beams by modal parameter shifts: A comparative study of burst and maintenance. The variation of the modal parameters with different levels of impact energy and density

  9. DETECTION OF ESCHERICHIA COLI 0157:H7 THROUGH THE FORMATION OF SANDWICHED COMPLEXES WITH IMMUNOMAGNETIC AND FLUORESCENT BEADS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new fluorescent sandwich method for the detection of Escherichia coli O157:H7 in ground beef was developed. Immunomagnetic beads (IMB) pre-coated with anti-E. coli O157 antibody were used to capture and concentrate E.coli O157:H7 present in ground beef. Streptavidin-coated fluorescent beads (SFB...

  10. Novel Sandwiched Intermetallic Selenoantimonates: Soft Synthesis and Characterization of Cu2SbSe3,0.5en

    E-print Network

    Li, Jing

    Novel Sandwiched Intermetallic Selenoantimonates: Soft Synthesis and Characterization of Cu2SbSe3 June 16, 1998 Two novel two-dimensional (layered) intermetallic copper selenoantimonates Cu2- SbSe3 molecules. The intermetallic layers are very similar in I and II, but the orientations of the solvent

  11. The Journey of a Sandwich: Computer-Based Laboratory Experiments about the Human Digestive System in High School Biology Teaching

    ERIC Educational Resources Information Center

    Sorgo, Andrej; Hajdinjak, Zdravka; Briski, Darko

    2008-01-01

    Teaching high school students about the digestive system can be a challenge for a teacher when s/he wants to overcome rote learning of facts without a deeper understanding of the physiological processes inside the alimentary tract. A series of model experiments illustrating the journey of a sandwich was introduced into teaching high school

  12. Optical Detection of Human Papillomavirus Type 16 and Type 18 by Sequence Sandwich Hybridization With Oligonucleotide-Functionalized Au Nanoparticles

    Microsoft Academic Search

    Sz-Hau Chen; Kun-I Lin; Chuan-Yi Tang; Sheng-Lung Peng; Yao-Chen Chuang; Yi-Rou Lin; Jui-Ping Wang; Chih-Sheng Lin

    2009-01-01

    The importance of detecting and subtyping human papillomaviruses (HPVs) in clinical and epidemiological studies has been well addressed. In detecting the most common types of HPV, type 16 (HPV-16) and type 18 (HPV-18), in the cervical mucous of patients in a simple and rapid manner, the assay of a label- free colorimetric DNA sensing method based on sequence sandwich hybridization

  13. Non-linear thermal response of sandwich panels with a flexible core and temperature dependent mechanical properties

    Microsoft Academic Search

    Yeoshua Frostig; Ole Thybo Thomsen

    2008-01-01

    The paper presents the geometrical non-linear response of unidirectional sandwich panels with a soft core subjected to thermally induced deformation type of loading, which may be fully distributed or localized. The mathematical formulation incorporates the effects of the flexibility of the core in the vertical direction as well as the effects of the temperature dependent mechanical properties of the constituent

  14. Design of load-bearing antenna structures by embedding technology of microstrip antenna in composite sandwich structure

    Microsoft Academic Search

    Chi Sang You; Woonbong Hwang

    2005-01-01

    Electrically and structurally effective antenna structure is developed for the next generation of surface technology for communication, in which the structural surface itself becomes an antenna. The basic design concept is a sandwich structure composed of composite laminates and Nomex honeycomb, with which microstrip antenna is integrated. Composite materials with high electrical loss must not reduce antenna efficiency. Stacked-patch microstrip

  15. Dynamic Stability and Static Stress State of a Sandwich Beam with a Metal Foam Core Using Three Modified Timoshenko Hypotheses

    Microsoft Academic Search

    E. Magnucka-Blandzi

    2011-01-01

    The subject of the paper is simply supported sandwich beams with a metal foam core. The fields of displacement for the flat cross section of the beam are defined by three different hypotheses. The mechanical properties of the isotropic metal foam core of the beam are varied in a normal direction in relation to the middle symmetry plane. Basing on

  16. Design of the composite sandwich panel of the hot pad for the bonding of large area adhesive films

    Microsoft Academic Search

    Soon Ho Yoon; Dai Gil Lee

    2011-01-01

    A light-weight hot pad system for curing large area adhesive films for the secondary barrier of cryogenic cargo containments of Liquefied Natural Gas (LNG) has been developed with a composite sandwich panel.In order to apply uniform pressure to the adhesive on unlevel insulation panels and to obtain an adequate adhesive thickness, a flexible stainless steel foil heater supported by a

  17. Thermal stability tests of CFRP sandwich panels for far infrared astronomy

    NASA Technical Reports Server (NTRS)

    Hoffmann, W. F.; Helwig, G.; Scheulen, D.

    1986-01-01

    An account is given of fabrication methods and low temperature figure tests for CFRP sandwich panels, in order to ascertain their applicability to ultralightweight 3-m aperture primary mirrors for balloon-borne sub-mm and far-IF telescopes that must maintain a 1-2 micron rms surface figure accuracy at -40 to -50 C. Optical figure measurements on the first two of a series of four 0.5-m test panels, replicated to a spherical surface, show a radius-of-curvature change and astigmatism down to -60 C; this approximately follows the composite's theoretical predictions and implies that material and process control is excellent, so that the large scale changes observed can be compensated for.

  18. Sizing Single Cantilever Beam Specimens for Characterizing Facesheet/Core Peel Debonding in Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.

    2010-01-01

    This paper details part of an effort focused on the development of a standardized facesheet/core peel debonding test procedure. The purpose of the test is to characterize facesheet/core peel in sandwich structure, accomplished through the measurement of the critical strain energy release rate associated with the debonding process. The specific test method selected for the standardized test procedure utilizes a single cantilever beam (SCB) specimen configuration. The objective of the current work is to develop a method for establishing SCB specimen dimensions. This is achieved by imposing specific limitations on specimen dimensions, with the objectives of promoting a linear elastic specimen response, and simplifying the data reduction method required for computing the critical strain energy release rate associated with debonding. The sizing method is also designed to be suitable for incorporation into a standardized test protocol. Preliminary application of the resulting sizing method yields practical specimen dimensions.

  19. Sandwich structure of Pd doped nanostructure TiO2 film as O2 sensor.

    PubMed

    Wang, Hairong; Sun, Quantao; Chen, Lei; Zhao, Yulong

    2013-09-01

    In this paper, we investigated the sensing properties of sandwich structure of TiO2/Pd/TiO2 thin films at various operating temperatures and oxygen partial pressures. The nanostructure TiO2 thin films were prepared by the sol-gel method. Various thickness of Pd buried layer was deposited by magnetron sputtering of a pure Pd target. The films were characterized using X-ray diffraction analysis and SEM. It was found that TiO2/Pd/TiO2 thin films have the p-type behavior while the pure TiO2 thin film is n-type semiconductor materials. We found that the structure of TiO2/Pd/TiO2 thin films with 10 s sputtering Pd layer has a better stability at 240 C. PMID:24089853

  20. Damage Evolution in Composite Materials and Sandwich Structures Under Impulse Loading

    NASA Astrophysics Data System (ADS)

    Silva, Michael Lee

    Damage evolution in composite materials is a rather complex phenomenon. There are numerous failure modes in composite materials stemming from the interaction of the various constituent materials and the particular loading conditions. This thesis is concerned with investigating damage evolution in sandwich structures under repeated transient loading conditions associated with impulse loading due to hull slamming of high-speed marine craft. To fully understand the complex stress interactions, a full field technique to reveal stress or strain is required. Several full field techniques exist but are limited to materials with particular optical properties. A full field technique applicable to most materials is known as thermoelastic stress analysis (TSA) and reveals the variation in sum of principal stresses of a cyclically loaded sample by correlating the stresses to a small temperature change occurring at the loading frequency. Digital image correlation (DIC) is another noncontact full field technique that reveals the deformation field by tracking the motion of subsets of a random speckle pattern during the loading cycles. A novel experimental technique to aid in the study of damage progression that combines TSA and DIC simultaneously utilizing a single infrared camera is presented in this thesis. A technique to reliably perform DIC with an infrared (IR) camera is developed utilizing variable emissivity paint. The thermal data can then be corrected for rigid-body motion and deformation such that each pixel represents the same material point in all frames. TSA is then performed on this corrected data, reducing motion blur and increasing accuracy. This combined method with a single infrared camera has several advantages, including a straightforward experimental setup without the need to correct for geometric effects of two spatially separate cameras. Additionally, there is no need for external lighting in TSA as the measured electromagnetic radiation is emitted by the sample's thermal fields. The particular stress resolution of TSA will depend on properties of the material of interest but the noise floor for the temperature variation is universal to the camera utilized. For the camera system in this thesis, the noise floor was found to be fairly frequency independent with a magnitude of 0.01 C, giving the minimum measurable stress for 2024 aluminum alloy of 3.6 MPa and for Nylon of 0.84 MPa. The average displacement range found during a static DIC test with IR images was 0.1 pixels. The maximum displacement variation at 1 Hz was 0.018 pixels. The average variation in strain at 1 Hz was 25 microstrain comparable to traditional DIC measurements in the visible optical regime. The combined TSA-DIC method in IR was validated with several benchmark example problems including plate structures with holes, cracks, and bimaterials. The validated technique was applied to foam-core sandwich composite beams under repeated simulated wave slamming loading. There are numerous failure modes in sandwich composite materials and the full field stress and strain from TSA and DIC, respectively, allow for improved failure analysis and prediction. Understanding damage in sandwich structures under impulse loading is a complex open area of research and the combined TSA-DIC method provides further insight into the failure process.

  1. Management of necrotic neck wounds with a sandwich pectoralis myocutaneous flap

    SciTech Connect

    Goldstein, R.D.; Komisar, A.; Silver, C.; Strauch, B.

    1988-03-01

    A modified pectoralis major myocutaneous flap was used to stabilize necrotic neck wounds rapidly in irradiated patients. The flap was a sandwich flap that included an overlying parasternal pectoral skin paddle for pharyngeal reconstruction, the pectoralis muscle for carotid protection, and a meshed skin graft applied to the undersurface of the muscle to replace cervical skin. This flap has been used to reconstruct seven patients with severe wound necrosis from pharyngeal fistula and infection. All patients had carotid exposure in the infected wound. Reconstruction in all patients accomplished restoration of pharyngeal continuity, carotid protection, and cervical skin replacement. Some patients required more than one procedure for closure. There were no carotid blowouts in any of the patients. This technique enables the head and neck surgeon to stabilize these contaminated wounds rapidly and to reconstruct complex defects of the pharynx and cervical skin.

  2. Local resonance and Bragg bandgaps in sandwich beams containing periodically inserted resonators

    E-print Network

    Sharma, Bhisham

    2015-01-01

    We study the low frequency wave propagation behavior of sandwich beams containing periodically embedded internal resonators. A closed form expression for the propagation constant is obtained using a phased array approach and verified using finite element simulations. We show that local resonance and Bragg bandgaps coexist in such a system and that the width of both bandgaps is a function of resonator parameters as well as their periodicity. The interaction between the two bandgaps is studied by varying the local resonance frequency. We find that a single combined bandgap does not exist for this system and that the Bragg bandgaps transition into sub-wavelength bandgaps when the local resonance frequency is above their associated classical Bragg frequency.

  3. Nonvolatile resistive switching in metal/La-doped BiFeO3/Pt sandwiches.

    PubMed

    Li, Mi; Zhuge, Fei; Zhu, Xiaojian; Yin, Kuibo; Wang, Jinzhi; Liu, Yiwei; He, Congli; Chen, Bin; Li, Run-Wei

    2010-10-22

    The resistive switching (RS) characteristics of a Bi(0.95)La(0.05)FeO(3) (La-BFO) film sandwiched between a Pt bottom electrode and top electrodes (TEs) made of Al, Ag, Cu, and Au have been studied. Devices with TEs made of Ag and Cu showed stable bipolar RS behaviors, whereas those with TEs made of Al and Au exhibited unstable bipolar RS. The Ag/La-BFO/Pt structure showed an on/off ratio of 10(2), a retention time > 10(5) s, and programming voltages < 1 V. The RS effect can be attributed to the formation/rupture of nanoscale metal filaments due to the diffusion of the TEs under a bias voltage. The maximum current before the reset process (on-to-off switching) was found to increase linearly with the current compliance applied during the set process (off-to-on switching). PMID:20858929

  4. Nonvolatile resistive switching in metal/La-doped BiFeO3/Pt sandwiches

    NASA Astrophysics Data System (ADS)

    Li, Mi; Zhuge, Fei; Zhu, Xiaojian; Yin, Kuibo; Wang, Jinzhi; Liu, Yiwei; He, Congli; Chen, Bin; Li, Run-Wei

    2010-10-01

    The resistive switching (RS) characteristics of a Bi0.95La0.05FeO3 (La-BFO) film sandwiched between a Pt bottom electrode and top electrodes (TEs) made of Al, Ag, Cu, and Au have been studied. Devices with TEs made of Ag and Cu showed stable bipolar RS behaviors, whereas those with TEs made of Al and Au exhibited unstable bipolar RS. The Ag/La-BFO/Pt structure showed an on/off ratio of 102, a retention time > 105 s, and programming voltages < 1 V. The RS effect can be attributed to the formation/rupture of nanoscale metal filaments due to the diffusion of the TEs under a bias voltage. The maximum current before the reset process (on-to-off switching) was found to increase linearly with the current compliance applied during the set process (off-to-on switching).

  5. Fabrication method for cores of structural sandwich materials including star shaped core cells

    DOEpatents

    Christensen, R.M.

    1997-07-15

    A method for fabricating structural sandwich materials having a core pattern which utilizes star and non-star shaped cells is disclosed. The sheets of material are bonded together or a single folded sheet is used, and bonded or welded at specific locations, into a flat configuration, and are then mechanically pulled or expanded normal to the plane of the sheets which expand to form the cells. This method can be utilized to fabricate other geometric cell arrangements than the star/non-star shaped cells. Four sheets of material (either a pair of bonded sheets or a single folded sheet) are bonded so as to define an area therebetween, which forms the star shaped cell when expanded. 3 figs.

  6. Fabrication method for cores of structural sandwich materials including star shaped core cells

    DOEpatents

    Christensen, Richard M. (Danville, CA)

    1997-01-01

    A method for fabricating structural sandwich materials having a core pattern which utilizes star and non-star shaped cells. The sheets of material are bonded together or a single folded sheet is used, and bonded or welded at specific locations, into a flat configuration, and are then mechanically pulled or expanded normal to the plane of the sheets which expand to form the cells. This method can be utilized to fabricate other geometric cell arrangements than the star/non-star shaped cells. Four sheets of material (either a pair of bonded sheets or a single folded sheet) are bonded so as to define an area therebetween, which forms the star shaped cell when expanded.

  7. Study on the prestressed sandwich piezoelectric ceramic ultrasonic transducer of torsional-flexural composite vibrational mode.

    PubMed

    Shuyu, Lin

    2002-08-01

    Based on the classical torsional and flexural vibrational theory of a slender rod, the prestressed sandwich torsional-flexural composite mode piezoelectric ceramic ultrasonic transducer is studied. This type of transducer consists of the slender metal rods and the longitudinally and tangentially polarized piezoelectric ceramic rings. The resonance frequency equations for the torsional and flexural vibrations in the transducers are derived. The simultaneous resonance of the torsional and flexural vibrations in the transducer is acquired by correcting the length of the metal slender rods resulting from the piezoelectric ceramic elements. The experimental results show that the measured resonance frequencies of the transducers are in good agreement with the computed ones, and the measured resonance frequencies of the torsional and the flexural vibrations in the composite transducers are also in good agreement with each other. PMID:12186032

  8. Large-area sandwich veto detector with WLS fibre readout for hadron spectroscopy at COMPASS

    NASA Astrophysics Data System (ADS)

    Schlter, T.; Dnnweber, W.; Dhibar, K.; Faessler, M.; Geyer, R.; Rajotte, J.-F.; Roushan, Z.; Whrmann, H.

    2011-10-01

    A sandwich detector composed of scintillator and steel-covered lead layers was introduced in the fixed-target COMPASS experiment at CERN for vetoing events not completely covered by the two-stage magnetic spectrometer. Wavelength shifting fibres glued into grooves in the scintillator tiles serve for fast readout. Minimum ionising particles impinging on the 2 m 2 m detector outside of a central hole, sparing the spectrometer's entry, are detected with a probability of 98%. The response to charged particles and photons is modelled in detail in Monte Carlo calculations. Figures of merit of the veto trigger in 190 GeV/ c?-+p (or nucleus) experiments are an enrichment of exclusive events in the recorded data by a factor of 3.5 and a false-veto probability of 1%.

  9. Double-antibody sandwich enzyme-linked immunosorbent assay for cellobiohydrolase I

    SciTech Connect

    Riske, F.J.; Eveleigh, D.E.; MacMillan, J.D. (Rutgers Univ., New Brunswick, NJ (USA))

    1990-11-01

    A double-antibody sandwich enzyme-linked immunosorbent assay was developed for quantifying cellobiohydrolase I (CBH I) in crude preparations of the cellulase complex from Trichoderma reesei. The other enzymes (endoglucanase and {beta}-glucosidase) in this complex and other ingredients in culture broth did not interfere with this assay. The antibody configuration that resulted in the highest specificity for the assay of CBH I employed a monoclonal antibody to coat wells in polystyrene plates and peroxidase-labeled polyclonal antibody to detect cellobiohydrolase bound to the immobilized monoclonal antibody. Previously, procedures have not been available for the direct assay of CBH I activity in the presence of the other enzymes in the complex, and current indirect procedures are cumbersome and inaccurate. The direct procedure described here is highly specific for CBH I and useful for quantifying this enzyme in the range of 0.1 to 0.8 {mu}g/ml.

  10. Theoretical prediction of the damping of a railway wheel with sandwich-type dampers

    NASA Astrophysics Data System (ADS)

    Merideno, Inaki; Nieto, Javier; Gil-Negrete, Nere; Gimnez Ortiz, Jos Germn; Landaberea, Aitor; Iartza, Jon

    2014-09-01

    This paper presents a procedure for predicting the damping added to a railway wheel when sandwich-type dampers are installed. Although there are different ways to reduce the noise generated by a railway wheel, most devices are based on the mechanism of increasing wheel damping. This is why modal damping ratios are a clear indicator of the efficiency of the damping device and essential when a vibro-acoustic study of a railway wheel is carried out. Based on a number of output variables extracted from the wheel and damper models, the strategy explained herein provides the final damping ratios of the damped wheel. Several different configurations are designed and experimentally tested. Theoretical and experimental results agree adequately, and it is demonstrated that this procedure is a good tool for qualitative comparison between different solutions in the design stages.

  11. Experimental and Numerical Analysis of Composite Folded Sandwich Core Structures Under Compression

    NASA Astrophysics Data System (ADS)

    Heimbs, S.; Middendorf, P.; Kilchert, S.; Johnson, A. F.; Maier, M.

    2007-11-01

    The characterisation of the mechanical behaviour of folded core structures for advanced sandwich composites under flatwise compression load using a virtual testing approach is presented. In this context dynamic compression test simulations with the explicit solvers PAM-CRASH and LS-DYNA are compared to experimental data of two different folded core structures made of aramid paper and carbon fibre-reinforced plastic (CFRP). The focus of the investigations is the constitutive modelling of the cell wall material, the consideration of imperfections and the representation of cell wall buckling, folding or crushing phenomena. The consistency of the numerical results shows that this can be a promising and efficient approach for the determination of the effective mechanical properties and a cell geometry optimisation of folded core structures.

  12. Fracture of Ceramic Liner and Head in a Total Hip Arthroplasty with a Sandwich Type Cup

    PubMed Central

    Retegui, Diego; Garca, Sebastin; Bori, Guillem; Gallart, Xavier

    2013-01-01

    Due to its advantages, ceramic-on-ceramic bearings have been widely used in young patients for almost 30 years. Long-term survivorship, low wear, and low biological reactivity to particles are some of its characteristics. Even though this material has had a lot of improvements, the risk of fracture is one of the concerns. There have been reports of fracture of ceramic in the acetabular liner and head but no fractures of both in the same patient. We report a case of a fracture in a sandwich type acetabular liner and the ceramic head in a patient involving ankylosing spondylitis. It occurred three years after the operation and with no history of direct trauma. We decided to change the bearing surfaces to metal polyethylene without removing the metal back. The patient is satisfied by the clinical results after a 5-year followup. PMID:23691392

  13. Fabrication and development of several heat pipe honeycomb sandwich panel concepts. [airframe integrated scramjet engine

    NASA Technical Reports Server (NTRS)

    Tanzer, H. J.

    1982-01-01

    The feasibility of fabricating and processing liquid metal heat pipes in a low mass honeycomb sandwich panel configuration for application on the NASA Langley airframe-integrated Scramjet engine was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts was evaluated within constraints dictated by existing manufacturing technology and equipment. The chosen design consists of an all-stainless steel structure, sintered screen facesheets, and two types of core-ribbon; a diffusion bonded wire mesh and a foil-screen composite. Cleaning, fluid charging, processing, and process port sealing techniques were established. The liquid metals potassium, sodium and cesium were used as working fluids. Eleven honeycomb panels 15.24 cm X 15.24 cm X 2.94 cm were delivered to NASA Langley for extensive performance testing and evaluation; nine panels were processed as heat pipes, and two panels were left unprocessed.

  14. Multi-Functional Sandwich Composites for Spacecraft Applications: An Initial Assessment

    NASA Technical Reports Server (NTRS)

    Adams, Daniel O.; Webb, Nicholas Jason; Yarger, Cody B.; Hunter, Abigail; Oborn, Kelli D.

    2007-01-01

    Current spacecraft implement relatively uncoupled material and structural systems to address a variety of design requirements, including structural integrity, damage tolerance, radiation protection, debris shielding and thermal insulation. This investigation provided an initial assessment of multi-functional sandwich composites to integrate these diverse requirements. The need for radiation shielding was addressed through the selection of polymeric constituents with high hydrogen content. To provide increased damage tolerance and debris shielding, manufacturing techniques were developed to incorporate transverse stitching reinforcement, internal layers, and a self-healing ionomer membrane. To assess the effects of a space environment, thermal expansion behavior of the candidate foam materials was investigated under a vacuum and increasing temperature. Finally, a thermal expansion model was developed for foam under vacuum conditions and its predictive capability assessed.

  15. Weight comparisons of optimized stiffened, unstiffened, and sandwich cylindrical shells made from composite or aluminum materials

    NASA Technical Reports Server (NTRS)

    Agarwal, B. L.; Sobel, L. H.

    1976-01-01

    This work presents optimum designs for unstiffened, hat stringer-stiffened and honeycomb sandwich cylinders under axial compression. Optimization results for graphite-epoxy cylinders show about a 50 percent weight savings over corresponding optimized aluminum cylinders for a wide loading range. The inclusion of minimum gage considerations results in a significant weight penalty, especially for a lightly loaded cylinder. Effects of employing a smeared stiffener buckling theory in the optimization program are investigated through comparison of results obtained from a more accurate branched shell buckling computer code. It was found that the stiffener cross-sectional deformations, which are usually ignored in smeared stiffener theory, result in about a 30 percent lower buckling load for the graphite-epoxy hat stiffened cylinder.

  16. Bending Response of Sandwiched Double Tube Structures with Aluminum Foam Core

    NASA Astrophysics Data System (ADS)

    Guo, L. W.; Yu, J. L.

    2010-05-01

    Three point bending response of sandwiched double cylindrical tube structures with aluminum foam core was studied numerically using the explicit finite element method. The numerical results are in good agreement with the corresponding experimental results and display the advantage of this new structure in load carrying capacity and energy absorption efficiency over the traditional foam-filled single tube structure. The deformation and failure mechanism is revealed by comparisons of the strain and stress distributions and the history of the maximum strain. The influence of the inner tube diameter for the structure was explored. It is found that increasing the inner tube diameter enhances the maximum deflection at failure of the foam-filled double tube within the diameter range considered. With a proper inner tube diameter, a steady load carrying capacity of the foam-filled double tube structure can be achieved, which shows an excellent crashworthiness with high energy absorption efficiency.

  17. Controlled release of metformin hydrochloride and repaglinide from sandwiched osmotic pump tablet.

    PubMed

    Qin, Chao; He, Wei; Zhu, Chunli; Wu, Mengmeng; Jin, Zhu; Zhang, Qiang; Wang, Guangji; Yin, Lifang

    2014-05-15

    The marketed compound tablet of metformin hydrochloride (MH) and repaglinide (RG) exhibits perfect multidrug therapeutic effect of type 2 diabetes. However, due to the short half life of the drugs, the tablet has to be administered 2 to 3 times a day, causing inconvenience to patient and fluctuations of plasma concentration. Here, a sandwiched osmotic pump tablet was developed to deliver the two drugs simultaneously at zero-order rate, in which MH and RG were loaded in different layers separated by a push layer. The osmotic pump tablet was prepared by a combination of three tableting procedure and film coating method. The factors including type and amount of propellant, osmotic active agents, amount of porogenic agent, coating weight, orifice diameter were optimized. The pharmacokinetic study was performed in beagle dogs, and the drug concentration in plasma samples was assayed by HPLC-MS/MS method. Simultaneous, controlled release of MH and RG in the first 12 and 8h was achieved from the optimized formulation. A significantly decreased Cmax, prolonged Tmax and satisfactory bioavailability of the osmotic pump tablet were obtained, and a good in vivo-in vitro correlation of the two drugs was also established. In summary, the sandwiched osmotic pump tablet released the MH and RG simultaneously at zero-order rate, and exhibited significant sustained release effect in vivo and good in vivo-in vitro correlation. The designed controlled release system for MH and RG proposed a promising replacement for the marked compound product in the therapy of type 2 diabetes. PMID:24607209

  18. Sandwich Plating for Intra-articular Distal Radius Fractures with Volar and Dorsal Metaphyseal Comminution

    PubMed Central

    Kamath, Atul F.; Makhni, Eric; Jean-Gilles, Jerome; Zurakowski, David

    2007-01-01

    Introduction Intra-articular distal radius fractures with volar and dorsal comminution present a special challenge to the hand surgeon. Methods Ten patients formed the study cohort. All plates were low profile and stainless steel. Radiographic parameters, range of motion, and strength compared to the uninjured side were recorded. Functional outcome was evaluated by Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire and Gartland and Werley scoring system. Results Median age at surgery was 58years (range, 24 to 86). Mean follow-up was 17months (range, 12 to 28). According to the AO classification system, there were three type C2 and seven type C3 fractures. Median preoperative dorsal angulation was 24deg; median postoperative dorsal angulation was 3deg. Eighty percent (8) of the fractures also had an intra-articular step-off or gap, all of which were corrected to neutral by the procedure. Compared with the contralateral side, mean extension and flexion were 73 and 75%, respectively, pronation and supination were 95 and 88%, respectively, and grip strength and thumb pinch were 72 and 87%, respectively. Mean postoperative DASH score was 16 points, and 70% (7) of the patients had Gartland and Werley scores of good or excellent. None of the patients needed to have their plates removed, and no extensor tendon rupture was reported. Conclusions The sandwich plating technique is an effective method of regaining near-anatomic reconstruction of intra-articular, volarly and dorsally comminuted distal radius fractures. Results from this study demonstrate that patients can expect to regain about 80% of their range of motion and strength. Moreover, 70% of the patients will have good to excellent functional outcomes. This is the first study to examine range of motion and functional outcome of low-profile sandwich plating without plate removal. PMID:18780121

  19. A sandwiched microarray platform for benchtop cell-based high throughput screening

    PubMed Central

    Wu, Jinhui; Wheeldon, Ian; Guo, Yuqi; Lu, Tingli; Du, Yanan; Wang, Ben; He, Jiankang; Hu, Yiqiao; Khademhosseini, Ali

    2010-01-01

    The emergence of combinatorial chemistries and the increased discovery of natural compounds have led to the production of expansive libraries of drug candidates and vast numbers of compounds with potentially interesting biological activities. Despite broad interest in high throughput screening (HTS) across varied fields of biological research, there has not been an increase in accessible HTS technologies. Here, we present a simple microarray sandwich system suitable for screening chemical libraries in cell-based assays at the benchtop. The microarray platform delivers chemical compounds to isolated cell cultures by sandwiching chemical-laden arrayed posts with cell-seeded microwells. In this way, an array of sealed cell-based assays was generated without cross-contamination between neighboring assays. After chemical exposure, cell viability was analyzed by fluorescence detection of cell viability indicator assays on a per microwell basis in a standard microarray scanner. We demonstrate the efficacy of the system by generating four hits from toxicology screens towards MCF-7 human breast cancer cells. Three of the hits were identified in a combinatorial screen of a library of natural compounds in combination with verapamil, a P-glycoprotein inhibitor. A fourth hit, 9-methoxy-camptothecin, was identified by screening the natural compound library in the absence of verapamil. The method developed here miniaturizes existing HTS systems and enables the screening of a wide array of individual or combinatorial libraries in a reproducible and scalable manner. We anticipate broad application of such a system as it is amenable to combinatorial drug screening in a simple, robust and portable platform. PMID:20965560

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

    NASA Astrophysics Data System (ADS)

    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 needs to be evaluated.

  1. Design and construction of a solar-electric vehicle

    SciTech Connect

    Bhavnani, S.H. (Auburn Univ., AL (United States). Dept. of Mechanical Engineering)

    1994-02-01

    Recent concerns relating to global warming caused by greenhouse gases, coupled with a growing awareness of the limited available resources of fossil fuels, have spurred an interest in alternative energy powered vehicles. This paper describes the analysis, development, and testing of an aerodynamic vehicle powered by photovoltaic cells. The primary components of the vehicle are the composite material body, the aluminum space frame, the wheel hubs and front suspension assembly, the drive train, and the electrical system. The frame was designed using finite element analysis with the components of the frame modeled as beam elements. The body, designed to have a very high strength-to-weight ratio, was of graphite/Kevlar/Nomex sandwich construction. Testing was carried out using the three-point bend test to determine the optimal sandwich cross-sectional configuration. The design of the front suspension, the wheel hubs, and the power transmission are also discussed. The electrical system, based on a monocrystalline photovoltaic cell assembly, and silver-zinc storage cells, is also described. Finally, results of the optimization routine developed are also described.

  2. Self assembly of sandwich-layered 2D silver(I) coordination polymers stabilized by argentophilic interactions: Synthesis, crystal structures and ab initio intramolecular energetics

    NASA Astrophysics Data System (ADS)

    Zorlu, Yunus; Can, Hatice

    2014-11-01

    Two different two-dimensional silver(I) coordination polymers, namely {[Ag2(dcpa)}n (1) and {[Ag2(ma)]}n (2), where dcpa = 4,5-dichlorophthalate; ma = maleate, were synthesized and structurally analyzed by single crystal X-ray diffraction technique. Complexes 1 and 2 represent 2D coordination polymer with metal-organic sandwich type. Two independent Ag(I) ions in both complexes are linked to constructed 2D layer by ?8-?3:?2:?2:?1 (for complex 1) and ?8-?3:?3:?2:?2 (for complex 2) carboxylate bridging fashions. The 2D layers of 1 are further extended into a three-dimensional (3D) supramolecular network by weak Cl⋯Cl interactions while 2D layers of 2 are linked by weak CH⋯O interactions into a 3D supramolecular framework. These two complexes exhibit considerable short Ag-Ag argentophilic interactions. The long-range corrected density functional theory (DFT) method was used to investigate intramolecular energetics, which are responsible for these 2D structures. Natural bond orbital (NBO) analysis with long-range corrected DFT method assists to understand these intramolecular interactions.

  3. Space construction data base

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Construction of large systems in space is a technology requiring the development of construction methods to deploy, assemble, and fabricate the elements comprising such systems. A construction method is comprised of all essential functions and operations and related support equipment necessary to accomplish a specific construction task in a particular way. The data base objective is to provide to the designers of large space systems a compendium of the various space construction methods which could have application to their projects.

  4. Building and ConstruCtion

    E-print Network

    California at Davis, University of

    Construction Management - Professional Education showcase If you are in the construction industry or any goals. As the construction industry becomes more complex, construction professionals need businessBuilding and ConstruCtion fall 2012 Construction Management Sustainability Studies & Green Building

  5. Improving the performance of dye-sensitized solar cells with TiO2/graphene/TiO2 sandwich structure

    PubMed Central

    2014-01-01

    This study investigates the extent to which the TiO2/graphene/TiO2 sandwich structure improves the performance of dye-sensitized solar cells (DSSCs) over that of DSSCs with the traditional structure. Studies have demonstrated that the TiO2/graphene/TiO2 sandwich structure effectively enhances the open circuit voltage (Voc), short-circuit current density (Jsc), and photoelectrical conversion efficiency (?) of DSSCs. The enhanced performance of DSSCs with the sandwich structure can be attributed to an increase in electron transport efficiency and in the absorption of light in the visible range. The DSSC with the sandwich structure in this study exhibited a Voc of 0.6 V, a high Jsc of 11.22 mA cm-2, a fill factor (FF) of 0.58, and a calculated ? of 3.93%, which is 60% higher than that of a DSSC with the traditional structure. PMID:25136284

  6. Endogenous bile acid disposition in rat and human sandwich-cultured hepatocytes

    SciTech Connect

    Marion, Tracy L., E-mail: tracylmarion@qualyst.com [Curriculum in Toxicology, UNC School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7270 (United States); Perry, Cassandra H., E-mail: cassandraperry@qualyst.com [Qualyst, Inc., Durham, NC 27713 (United States); St Claire, Robert L., E-mail: bobstclaire@qualyst.com [Qualyst, Inc., Durham, NC 27713 (United States); Brouwer, Kim L.R., E-mail: kbrouwer@unc.edu [Division of Pharmacotherapy and Experimental Therapeutics, UNC Eshelman School of Pharmacy, The University of North Carolina at Chapel Hill, CB 7569 Kerr Hall, Chapel Hill, NC 27599-7569 (United States)

    2012-05-15

    Sandwich-cultured hepatocytes (SCH) are used commonly to investigate hepatic transport protein-mediated uptake and biliary excretion of substrates. However, little is known about the disposition of endogenous bile acids (BAs) in SCH. In this study, four endogenous conjugated BAs common to rats and humans [taurocholic acid (TCA), glycocholic acid (GCA), taurochenodeoxycholic acid (TCDCA), and glycochenodeoxycholic acid (GCDCA)], as well as two BA species specific to rodents (?- and ?-tauromuricholic acid; ?/? TMCA), were profiled in primary rat and human SCH. Using B-CLEAR{sup } technology, BAs were measured in cells + bile canaliculi, cells, and medium of SCH by LC-MS/MS. Results indicated that, just as in vivo, taurine-conjugated BA species were predominant in rat SCH, while glycine-conjugated BAs were predominant in human SCH. Total intracellular BAs remained relatively constant over days in culture in rat SCH. Total BAs in control (CTL) cells + bile, cells, and medium were approximately 3.4, 2.9, and 8.3-fold greater in human than in rat. The estimated intracellular concentrations of the measured total BAs were 64.3 5.9 ?M in CTL rat and 183 56 ?M in CTL human SCH, while medium concentrations of the total BAs measured were 1.16 0.21 ?M in CTL rat SCH and 9.61 6.36 ?M in CTL human SCH. Treatment of cells for 24 h with 10 ?M troglitazone (TRO), an inhibitor of the bile salt export pump (BSEP) and the Na{sup +}-taurocholate cotransporting polypeptide (NTCP), had no significant effect on endogenous BAs measured at the end of the 24-h culture period, potentially due to compensatory mechanisms that maintain BA homeostasis. These data demonstrate that BAs in SCH are similar to in vivo, and that SCH may be a useful in vitro model to study alterations in BA disposition if species differences are taken into account. -- Highlights: ? Bile acids (BAs) were measured in rat and human sandwich-cultured hepatocytes (SCH). ? Cell and medium BA concentrations were estimated using B-CLEAR{sup } technology. ? Endogenous BA profiles in SCH were similar to those reported in vivo for each species. ? Species differences were evident in endogenous BA profiles of rat vs human SCH. ? 10 M troglitazone had no effect on endogenous BA profiles in rat or human SCH at 24 h.

  7. Development Of Advanced Sandwich Core Topologies Using Fused Deposition Modeling And Electroforming Processes

    NASA Astrophysics Data System (ADS)

    Storck, Steven M.

    New weight efficient materials are needed to enhance the performance of vehicle systems allowing increased speed, maneuverability and fuel economy. This work leveraged a multi-length-scale composite approach combined with hybrid material methodology to create new state-of-the-art additive manufactured sandwich core material. The goal of the research was to generate a new material to expands material space for strength versus density. Fused-Deposition-Modeling (FDM) was used to remove geometric manufacturing constraints, and electrodepositing was used to generate a high specific-strength, bio-inspired hybrid material. Microtension samples (3mm x 1mm with 250mum x 250mum gage) were used to investigate the electrodeposited coatings in the transverse (TD) and growth (GD) directions. Three bath chemistries were tested: copper, traditional nickel sulfamate (TNS) nickel, and nickel deposited with a platinum anode (NDPA). NDPA shows tensile strength exceeding 1600 MPa, significantly beyond the literature reported values of 60MPa. This strengthening was linked to grain size refinement into the sub-30nm range, in addition to grain texture refinement resulting in only 17% of the slip systems for nickel being active. Anisotropy was observed in nickel deposits, which was linked to texture evolution inside of the coating. Microsample testing guided the selection of 15mum layer of copper deposition followed by a 250 mum NDPA layer. Classical formulas for structural collapse were used to guide an experimental parametric study to establish a weight/volume efficient strut topology. Length, diameter and thickness were all investigated to determine the optimal column topology. The most optimal topology exists when Eulerian buckling, shell micro buckling and yielding failure modes all exist in a single geometric topology. Three macro-scale sandwich topologies (pyramidal, tetrahedral, and strut-reinforced-tetrahedral (SRT) were investigated with respect to strength-per-unit-weight. The topologies were optimized across length scales using texture on the nano-scale microsamples on the micro-scale, and the parametric column study on the meso-scale. The results showed that additive manufacturing as a viable method for removing geometric constraints observed by other manufacturing methods. The SRT was the most optimized topology showing the highest strength-per-unit-weight. The final topology sits in a best-of-both areas of material space exceeding the commercially available honeycombs strength per relative density by 1670%.

  8. Standard practice for radiologic examination of flat panel composites and sandwich core materials used in aerospace applications

    E-print Network

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This practice is intended to be used as a supplement to Practices E 1742, E 1255, and E 2033. 1.2 This practice describes procedures for radiologic examination of flat panel composites and sandwich core materials made entirely or in part from fiber-reinforced polymer matrix composites. Radiologic examination is: a) radiographic (RT) with film, b) Computed Radiography (CR) with Imaging Plate, c) Digital Radiology (DR) with Digital Detector Arrays (DDA), and d) Radioscopic (RTR) Real Time Radiology with a detection system such as an Image Intensifier. The composite materials under consideration typically contain continuous high modulus fibers (> 20 GPa), such as those listed in 1.4. 1.3 This practice describes established radiological examination methods that are currently used by industry that have demonstrated utility in quality assurance of flat panel composites and sandwich core materials during product process design and optimization, process control, after manufacture inspection, in service exami...

  9. Sandwich nanoarchitecture of Si/reduced graphene oxide bilayer nanomembranes for Li-ion batteries with long cycle life.

    PubMed

    Liu, Xianghong; Zhang, Jun; Si, Wenping; Xi, Lixia; Eichler, Barbara; Yan, Chenglin; Schmidt, Oliver G

    2015-02-24

    The large capacity loss and huge volume change of silicon anodes severely restricts their practical applications in lithium ion batteries. In this contribution, the sandwich nanoarchitecture of rolled-up Si/reduced graphene oxide bilayer nanomembranes was designed via a strain released strategy. Within this nanoarchitecture, the inner void space and the mechanical feature of nanomembranes can help to buffer the strain during lithiation/delithiation; the alternately stacked conductive rGO layers can protect the Si layers from excessive formation of SEI layers. As anodes for lithium-ion batteries, the sandwiched Si/rGO nanoarchitecture demonstrates long cycling life of 2000 cycles at 3 A g(-1) with a capacity degradation of only 3.3% per 100 cycles. PMID:25646575

  10. Unique Charge Storage Characteristics of FEP/THV/FEP Sandwich Electret Membrane Polarized by Thermally Charging Technology

    NASA Astrophysics Data System (ADS)

    Chen, Gang-Jin; Lei, Ming-Feng; Xiao, Hui-Ming; Wu, Ling

    2014-12-01

    Utilizing the synergy of three processes (space charge injection, dipole orientation and interfacial polarization) which determine the electret properties, a sandwich electret membrane FEP/THV/FEP (FEP: fluorinated ethylene propylene, THV: tetrafluoroethylene-hexafluoropropylene-vinylidene) is prepared by the laminating method and the thermal charging technology. The surface potential measurement indicates that the sandwich electret membrane exhibits excellent charge storage stability. When washing the sample surface with alcohol, its surface potential first undergoes decay to zero, and then quickly restores to a high value. The surface potential value is associated with the charging electric field and temperature. The best charging condition is 18.75 MVm?1 and 130C. A charge storage profile is proposed, and the experimental results are in good agreement with this profile.

  11. A Damage Tolerance Comparison of Composite Hat-Stiffened and Honeycomb Sandwich Structure for Launch Vehicle Interstage Applications

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.

    2011-01-01

    In this study, a direct comparison of the compression-after-impact (CAI) strength of impact-damaged, hat-stiffened and honeycomb sandwich structure for launch vehicle use was made. The specimens used consisted of small substructure designed to carry a line load of approx..3,000 lb/in. Damage was inflicted upon the specimens via drop weight impact. Infrared thermography was used to examine the extent of planar damage in the specimens. The specimens were prepared for compression testing to obtain residual compression strength versus damage severity curves. Results show that when weight of the structure is factored in, both types of structure had about the same CAI strength for a given damage level. The main difference was that the hat-stiffened specimens exhibited a multiphase failure whereas the honeycomb sandwich structure failed catastrophically.

  12. An experimental correlation study between field-target overlap and sensitivity of surface plasmon resonance biosensors based on sandwiched immunoassays

    NASA Astrophysics Data System (ADS)

    Ryu, Yeonsoo; Moon, Seyoung; Oh, Youngjin; Kim, Yonghwi; Kim, Donghyun

    2012-10-01

    In this report, we have studied the effectiveness of field-target overlap to evaluate detection sensitivity of surface plasmon resonance (SPR) biosensors. The investigation used theoretical analysis based on the transfer matrix method, which was experimentally confirmed by thin film-based detection in sandwich and reverse sandwich immunoglobulin G (IgG) assays. Both theoretical and experimental results show that strong correlation exists between the overlap and the sensitivity with the coefficient of correlation higher than 95% in all the cases that we have considered. We have also confirmed the correlation in diffraction grating-based SPR measurement of IgG/anti-IgG interactions. The correlation elucidates the mechanism behind the far-field detection sensitivity of SPR biosensors and can lead to the enhancement of SPR biosensing with molecular scale sensitivity.

  13. Higher-order dynamic response of composite sandwich panels with flexible core under simultaneous low-velocity impacts of multiple small masses

    Microsoft Academic Search

    K. Malekzadeh; M. R. Khalili; R. Olsson; A. Jafari

    2006-01-01

    Small mass impactors, such as runway debris and hailstones may result in a wave controlled local response, which is essentially independent of boundary conditions. The higher-order impact model of sandwich beams presented by Mijia and Pizhong [Mijia, Y., Pizhong, Q., 2005. Higher-order impact modeling of sandwich structures with flexible core. International Journal of Solids and Structures 42 (10), 54605490] is

  14. Static and low-velocity impact behavior of sandwich beams with closed-cell aluminum-foam core in three-point bending

    Microsoft Academic Search

    Jilin Yu; Erheng Wang; Jianrong Li; Zhijun Zheng

    2008-01-01

    In this paper, the response and failure of sandwich beams with aluminum-foam core are investigated. Quasi-static and low-velocity impact bending tests are carried out for sandwich beams with aluminum-foam core. The deformation and failure behavior is explored. It is found that the failure mode and the load history predicted by a modified Gibson's model agree well with the quasi-static experimental

  15. Evaluation of the manufacture of sound absorbent sandwich plank made of PET\\/TPU honeycomb grid\\/PU foam

    Microsoft Academic Search

    Jia-Horng Lin; Chin-Mei Lin; Chao-Chiung Huang; Chia-Chang Lin; Chien-Teng Hsieh; Yu-Chen Liao

    2011-01-01

    In this study, the sandwich plank consisted of 7D polyethylene teraphthalate (PET), thermoplastic polyurethane (TPU) honeycomb grid, and polyurethane (PU) foam; 7D PET and 4D low melting polyester fibers were needle-punched and thermal-treated so as to form the PET nonwoven layer. The PU foam was foamed with a different density in the mold so as to form the PU foam

  16. Development of a sandwich Dot-ELISA for detecting bovine viral diarrhea virus antigen with E2 recombinant protein

    Microsoft Academic Search

    Yuelan Zhao; Yuzhu Zuo; Lei Zhang; Jinghui Fan; Hanchun Yang; Jianhua Qin

    2009-01-01

    The IgG antibodies of rabbit anti-E2 protein of the bovine viral diarrhea virus were prepared by a general method from high\\u000a efficiency serum immunized by E2 recombinant protein antigen expressed in E. coli prokaryotic expression system and were labeled to make enzyme-labeled antibody with the method of NaIO4. A sandwich Dot enzyme-linked immunosorbent assay (Dot-ELISA) for the detection of BVDV

  17. Impact damage detection in light composite sandwich panels using piezo-based nonlinear vibro-acoustic modulations

    NASA Astrophysics Data System (ADS)

    Pieczonka, L.; Ukowski, P.; Klepka, A.; Staszewski, W. J.; Uhl, T.; Aymerich, F.

    2014-10-01

    The nonlinear vibro-acoustic modulation technique is used for impact damage detection in light composite sandwich panels. The method utilizes piezo-based low-frequency vibration and high-frequency ultrasonic excitations. The work presented focuses on the analysis of modulation intensity. The results show that the method can be used for impact damage detection reliably separating damage-related from vibro-acoustic modulations from other intrinsic nonlinear modulations.

  18. A portable and antibody-free sandwich assay for determination of chloramphenicol in food based on a personal glucose meter.

    PubMed

    Chen, Si; Gan, Ning; Zhang, Huairong; Hu, Futao; Li, Tianhua; Cui, Huan; Cao, Yuting; Jiang, Qianli

    2015-03-01

    A portable and antibody-free sandwich assay was fabricated for determination of chloramphenicol (CAP) in animal-derived food by a personal glucose meter (PGM). The sandwich-type strategy was developed on the basis of magnetic molecularly imprinted probe (m-MIP) nanoparticles and a ?-cyclodextrin/invertase-functionalized signal tag. Firstly, the m-MIPs were fabricated using polydopamine molecularly imprinted film modified Fe3O4 nanoparticles with 2,2-dichloroacetamide as a templatethat could capture the 2,2-dichloroacetamide segment of CAP. Secondly, ?-cyclodextrin/invertase polymer bioconjungate was synthesized as a signal tag that could recognize the nitrobenzene segment of CAP through host-guest interaction. The dual-specificity recognition model relies on the formation of a sandwich between m-MIPs, different segments of CAP, and the ?-cyclodextrin-functionalized signal tag. The sandwich-type complex formed was then subjected to detection with a PGM. The complexes can hydrolyze sucrose to glucose, which can be used for detection with a PGM through invertase. According to our experiment, the concentration of CAP was proportional to the amount of glucose formed, which could quantitatively assess the CAP with a dynamic range of 0.5-50ngmL(-1) and a detection limit of 0.16ngmL(-1) (signal-to-noise ratio of 3). The detection time of the assay was about 1h, which was obviously shorter than that of competitive ELISA. More importantly, we have successfully applied this on-site assay for CAP screening in animal-derived food. PMID:25644521

  19. Development and validation of a sandwich ELISA for the determination of potentially allergenic sesame ( Sesamum indicum ) in food

    Microsoft Academic Search

    Gerda Redl; Fatima T. Husain; Ines E. Bretbacher; Albert Nemes; Margit Cichna-Markl

    2010-01-01

    This paper presents a sandwich enzyme-linked immunosorbent assay (ELISA) that allows the determination of traces of sesame\\u000a in food. Chicken anti-sesame antibodies, used as coating antibodies, and rabbit anti-sesame antibodies, used as secondary\\u000a antibodies, were prepared by immunization with a protein extract of white, peeled sesame. The ELISA did not show any cross-reactivity\\u000a with 19 food ingredients commonly found in

  20. Analytical Prediction of Low-velocity Impact Response of Composite Sandwich Panels using New TDOF Springmassdamper Model

    Microsoft Academic Search

    K. Malekzadeh; M. R. Khalili; R. K. Mittal

    2006-01-01

    A new equivalent three-degree-of-freedom (TDOF) springmass damper (SMD) model has proposed to predict the low-velocity impact response of composite sandwich panels with transversely flexible core. Impacts are assumed to occur normally over the top face-sheet with the arbitrary different impactor masses and initial velocities. The interaction between the impactor and the panel is modeled with the help of a new