Science.gov

Sample records for aluminum honeycomb core

  1. An examination of impact damage in glass-phenolic and aluminum honeycomb core composite panels

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.; Lance, D. G.; Hodge, A. J.

    1990-01-01

    An examination of low velocity impact damage to glass-phenolic and aluminum core honeycomb sandwich panels with carbon-epoxy facesheets is presented. An instrumented drop weight impact test apparatus was utilized to inflict damage at energy ranges between 0.7 and 4.2 joules. Specimens were checked for extent of damage by cross sectional examination. The effect of core damage was assessed by subjecting impact-damaged beams to four-point bend tests. Skin-only specimens (facings not bonded to honeycomb) were also tested for comparison purposes. Results show that core buckling is the first damage mode, followed by delaminations in the facings, matrix cracking, and finally fiber breakage. The aluminum honeycomb panels exhibited a larger core damage zone and more facing delaminations than the glass-phenolic core, but could withstand more shear stress when damaged than the glass-phenolic core specimens.

  2. Aluminum Honeycomb Characteristics in Dynamic Crush Environments

    SciTech Connect

    Bateman, Vesta I.; Swanson, Lloyd H.

    1999-07-01

    Fifteen aluminum honeycomb cubes (3 in.) have been crushed in the Mechanical Shock Laboratory's drop table testing machines. This report summarizes shock experiments with honeycomb densities of 22.1 pcf and 38.0 pcf and with crush weights of 45 lb, 168 lb, and 268 lb. The honeycomb samples were crushed in all three orientations, W, L, and T. Most of the experiments were conducted at an impact velocity of {approx}40 fps, but higher velocities of up to 90 fps were used for selected experiments. Where possible, multiple experiments were conducted for a specific orientation and density of the honeycomb samples. All results are for Hexcel honeycomb except for one experiment with Alcore honeycomb and have been evaluated for validity. This report contains the raw acceleration data measured on the top of the drop table carriage, pictures of the crushed samples, and normalized force-displacement curves for all fifteen experiments. These data are not strictly valid for material characteristics in L and T orientations because the cross-sectional area of the honeycomb changed (split) during the crush. However, these are the best data available at this time. These dynamic crush data do suggest a significant increase in crush strength to 8000 psi ({approximately} 25-30% increase) over quasi-static values of {approximately}6000 psi for the 38.0 pcf Hexcel Honeycomb in the T-orientation. An uncertainty analysis is included and estimates the error in these data.

  3. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15...15 Verification of aluminum honeycomb crush strength. The following procedure is used to ascertain the crush strength of the main honeycomb block...

  4. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15...15 Verification of aluminum honeycomb crush strength. The following procedure is used to ascertain the crush strength of the main honeycomb block...

  5. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15...15 Verification of aluminum honeycomb crush strength. The following procedure is used to ascertain the crush strength of the main honeycomb block...

  6. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15...15 Verification of aluminum honeycomb crush strength. The following procedure is used to ascertain the crush strength of the main honeycomb block...

  7. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15...15 Verification of aluminum honeycomb crush strength. The following procedure is used to ascertain the crush strength of the main honeycomb block...

  8. The total hemispheric emissivity of painted aluminum honeycomb at cryogenic temperatures

    SciTech Connect

    Tuttle, J.; Canavan, E.; DiPirro, M.; Li, X.; Knollenberg, P.

    2014-01-29

    NASA uses high-emissivity surfaces on deep-space radiators and thermal radiation absorbers in test chambers. Aluminum honeycomb core material, when coated with a high-emissivity paint, provides a lightweight, mechanically robust, and relatively inexpensive black surface that retains its high emissivity down to low temperatures. At temperatures below about 100 Kelvin, this material performs much better than the paint itself. We measured the total hemispheric emissivity of various painted honeycomb configurations using an adaptation of an innovative technique developed for characterizing thin black coatings. These measurements were performed from room temperature down to 30 Kelvin. We describe the measurement technique and compare the results with predictions from a detailed thermal model of each honeycomb configuration.

  9. 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.

  10. Characterization of Thermal and Mechanical Impact on Aluminum Honeycomb Structures

    NASA Technical Reports Server (NTRS)

    Robinson, Christen M.

    2013-01-01

    This study supports NASA Kennedy Space Center's research in the area of intelligent thermal management systems and multifunctional thermal systems. This project addresses the evaluation of the mechanical and thermal properties of metallic cellular solid (MCS) materials; those that are lightweight; high strength, tunable, multifunctional and affordable. A portion of the work includes understanding the mechanical properties of honeycomb structured cellular solids upon impact testing under ambient, water-immersed, liquid nitrogen-cooled, and liquid nitrogen-immersed conditions. Additionally, this study will address characterization techniques of the aluminum honeycomb's ability to resist multiple high-rate loadings or impacts in varying environmental conditions, using various techniques for the quantitative and qualitative determination for commercial applicability.

  11. Evaluation of Ceramic Honeycomb Core Compression Behavior at Room Temperature

    NASA Technical Reports Server (NTRS)

    Bird, Richard K.; Lapointe, Thomas S.

    2013-01-01

    Room temperature flatwise compression tests were conducted on two varieties of ceramic honeycomb core specimens that have potential for high-temperature structural applications. One set of specimens was fabricated using strips of a commercially-available thin-gage "ceramic paper" sheet molded into a hexagonal core configuration. The other set was fabricated by machining honeycomb core directly from a commercially available rigid insulation tile material. This paper summarizes the results from these tests.

  12. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 7 2014-10-01 2014-10-01 false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL... Deformable Barrier § 587.15 Verification of aluminum honeycomb crush strength. The following procedure...

  13. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 7 2012-10-01 2012-10-01 false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL... Deformable Barrier § 587.15 Verification of aluminum honeycomb crush strength. The following procedure...

  14. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL... Deformable Barrier § 587.15 Verification of aluminum honeycomb crush strength. The following procedure...

  15. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 7 2013-10-01 2013-10-01 false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL... Deformable Barrier § 587.15 Verification of aluminum honeycomb crush strength. The following procedure...

  16. 49 CFR 587.15 - Verification of aluminum honeycomb crush strength.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 7 2011-10-01 2011-10-01 false Verification of aluminum honeycomb crush strength. 587.15 Section 587.15 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL... Deformable Barrier § 587.15 Verification of aluminum honeycomb crush strength. The following procedure...

  17. Double-Lap Shear Test For Honeycomb Core

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Hodge, Andrew J.

    1992-01-01

    Double-lap test measures shear strength of panel made of honeycomb core with 8-ply carbon-fiber/epoxy face sheets. Developed to overcome three principal disadvantages of prior standard single-lap shear test: specimen had to be more than 17 in. long; metal face sheets had to be used; and test introduced torque, with consequent bending and peeling of face sheets and spurious tensile or compressive loading of honeycomb.

  18. Honeycomb Core Permeability Under Mechanical Loads

    NASA Technical Reports Server (NTRS)

    Glass, David E.; Raman, V. V.; Venkat, Venki S.; Sankaran, Sankara N.

    1997-01-01

    A method for characterizing the air permeability of sandwich core materials as a function of applied shear stress was developed. The core material for the test specimens was either Hexcel HRP-3/16-8.0 and or DuPont Korex-1/8-4.5 and was nominally one-half inch thick and six inches square. The facesheets where made of Hercules' AS4/8552 graphite/epoxy (Gr/Ep) composites and were nominally 0.059-in. thick. Cytec's Metalbond 1515-3M epoxy film adhesive was used for co-curing the facesheets to the core. The permeability of the specimens during both static (tension) and dynamic (reversed and non-reversed) shear loads were measured. The permeability was measured as the rate of air flow through the core from a circular 1-in2 area of the core exposed to an air pressure of 10.0 psig. In both the static and dynamic testing, the Korex core experienced sudden increases in core permeability corresponding to a core catastrophic failure, while the URP core experienced a gradual increase in the permeability prior to core failure. The Korex core failed at lower loads than the HRP core both in the transverse and ribbon directions.

  19. Heat Transfer in Adhesively Bonded Honeycomb Core Panels

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran

    2001-01-01

    The Swann and Pittman semi-empirical relationship has been used as a standard in aerospace industry to predict the effective thermal conductivity of honeycomb core panels. Recent measurements of the effective thermal conductivity of an adhesively bonded titanium honeycomb core panel using three different techniques, two steady-state and one transient radiant step heating method, at four laboratories varied significantly from each other and from the Swann and Pittman predictions. Average differences between the measurements and the predictions varied between 17 and 61% in the temperature range of 300 to 500 K. In order to determine the correct values of the effective thermal conductivity and determine which set of the measurements or predictions were most accurate, the combined radiation and conduction heat transfer in the honeycomb core panel was modeled using a finite volume numerical formulation. The transient radiant step heating measurements provided the best agreement with the numerical results. It was found that a modification of the Swann and Pittman semi-empirical relationship which incorporated the facesheets and adhesive layers in the thermal model provided satisfactory results. Finally, a parametric study was conducted to investigate the influence of adhesive thickness and thermal conductivity on the overall heat transfer through the panel.

  20. A Model for Simulating the Response of Aluminum Honeycomb Structure to Transverse Loading

    NASA Technical Reports Server (NTRS)

    Ratcliffe, James G.; Czabaj, Michael W.; Jackson, Wade C.

    2012-01-01

    A 1-dimensional material model was developed for simulating the transverse (thickness-direction) loading and unloading response of aluminum honeycomb structure. The model was implemented as a user-defined material subroutine (UMAT) in the commercial finite element analysis code, ABAQUS(Registered TradeMark)/Standard. The UMAT has been applied to analyses for simulating quasi-static indentation tests on aluminum honeycomb-based sandwich plates. Comparison of analysis results with data from these experiments shows overall good agreement. Specifically, analyses of quasi-static indentation tests yielded accurate global specimen responses. Predicted residual indentation was also in reasonable agreement with measured values. Overall, this simple model does not involve a significant computational burden, which makes it more tractable to simulate other damage mechanisms in the same analysis.

  1. A Numerical Study on the Effect of Facesheet-Core Disbonds on the Buckling Load of Curved Honeycomb Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Pineda, Evan J.; Myers, David E.; Bednarcyk, Brett A.; Krivanek, Thomas M.

    2015-01-01

    A numerical study on the effect of facesheet-core disbonds on the post-buckling response of curved honeycomb sandwich panels is presented herein. This work was conducted as part of the development of a damage tolerance approach for the next-generation Space Launch System heavy lift vehicle payload fairing. As such, the study utilized full-scale fairing barrel segments as the structure of interest. The panels were composed of carbon fiber reinforced polymer facesheets and aluminum honeycomb core. The panels were analyzed numerically using the finite element method. Facesheet and core nodes in a predetermined circular region were detached to simulate a disbond induced via low-speed impact between the outer mold line facesheet and honeycomb core. Surface-to-surface contact in the disbonded region was invoked to prevent interpenetration of the facesheet and core elements. The diameter of this disbonded region was varied and the effect of the size of the disbond on the post-buckling response was observed. A significant change in the slope of the edge load-deflection response was used to determine the onset of global buckling and corresponding buckling load.

  2. Segmented Aluminum Honeycomb Characteristics in T-Direction, Dynamic Crush Environments

    SciTech Connect

    BATEMAN,VESTA I.; BROWN,FREDERICK A.; NUSSER,MICHAEL A.; SWANSON,LLOYD H.

    2000-08-23

    Thirteen segmented aluminum honeycomb samples (5 in. diameter and 1.5 in. height) have been crushed in an experimental configuration that uses a drop table impact machine. The 38.0 pcf bulk density samples are a unique segmented geometry that allows the samples to be crushed while maintaining a constant cross-sectional area. A crush weight of 175 lb was used to determine the rate sensitivity of the honeycomb's highest strength orientation, T-direction, in a dynamic environment of {approx}50 fps impact velocity. Experiments were conducted for two honeycomb manufacturers and at two temperatures, ambient and +165 F. Independent measurements of the crush force were made with a custom load cell and a force derived from acceleration measurements on the drop table using the Sum of Weighted Accelerations Technique with a Calibrated Force (SWAT-CAL). Normalized stress-strain curves for all thirteen experiments are included and have excellent repeatability. These data are strictly valid for material characteristics in the T orientation because the cross-sectional area of the honeycomb did not change during the crush. The dynamic crush data have a consistent increase in crush strength of {approximately}7--19% as compared to quasi-static data and suggest that dynamic performance may be inferred from static tests. An uncertainty analysis estimates the error in these data is {+-} 11%.

  3. Dynamic Crush Behaviors Of Aluminum Honeycomb Specimens Under Compression Dominant Inclined Loads

    SciTech Connect

    Hong, Sung-tae; Pan, Jwo; Tyan, Tau; Prasad, Priya

    2008-01-01

    The quasi-static and dynamic crush behaviors of aluminum 5052-H38 honeycomb specimens under out-of-plane inclined loads are investigated by experiments. Different types of honeycomb specimens were designed for crush tests under pure compressive and inclined loads with respect to the out-of-plane direction. A test fixture was designed for both quasi-static and dynamic crush tests under inclined loads. The results of the quasi-static crush tests indicate that the normal crush and shear strengths under inclined loads are consistent with the corresponding results under combined loads. The results of the dynamic crush tests indicate that as the impact velocity increases, the normal crush strength increases and the shear strength remains nearly the same. The trends of the normalized normal crush strengths under inclined loads for specimens with different in-plane orientation angles as functions of the impact velocity are very similar to each other. Based on the experimental results, a macroscopic yield criterion as a function of the impact velocity is proposed. The experimental results suggest that as the impact velocity increases, the shape of the macroscopic yield surface changes, or more specifically, the curvature of the yield surface increases near the pure compression state. The experimental results also show similar microscopic progressive folding mechanisms in honeycomb specimens under pure compressive and inclined loads. However, honeycomb specimens under inclined loads show inclined stacking patterns of folds due to the asymmetric location of horizontal plastic hinge lines.

  4. Evaluation of a bi-directional aluminum honeycomb impact limiter design

    SciTech Connect

    Doman, M.J.

    1995-12-01

    A 120 Ton shipping cask is being developed for the on-site shipment of dry spent fuel at the Idaho National Engineering Laboratory. Impact limiters were incorporated in the cask design to limit the inertial load of the package and its contents during the hypothetical 9-meter (30-foot) drop accident required by 10CFR71. The design process included: (1) a series of static and dynamic tests to determine the crush characteristics of the bi-directional aluminum honeycomb impact limiter material, (2) the development of an analytical model to predict the cask deceleration force as a function of impact limiter crush, and (3) a series of quarter scale model drop tests to qualify the analytical model. The scale model testing, performed at Sandia National Laboratory in Albuquerque, New Mexico, revealed several design aspects which should be considered in developing bi-directional aluminum honeycomb impact limiters and several other design aspects which should be considered for impact limiter designs in general.

  5. Mode I Toughness Measurements of Core/Facesheet Bonds in Honeycomb Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Ratcliffe, James G.

    2006-01-01

    Composite sandwich structures will be used in many future applications in aerospace, marine and offshore industries due to the fact that the strength and stiffness to mass ratios surpass any other structural type. Sandwich structure also offers advantages over traditional stiffened panels such as ease of manufacturing and repair. During the last three decades, sandwich structure has been used extensively for secondary structure in aircraft (fuselage floors, rudders and radome structure). Sandwich structure is also used as primary structure in rotorcraft, the most common example being the trailing edge of rotor blades. As with other types of composite construction, sandwich structure exhibits several types of failure mode such as facesheet wrinkling, core crushing and sandwich buckling. Facesheet/core debonding has also been observed in the marine and aerospace industry. During this failure mode, peel stresses applied to an existing facesheet/core debond or an interface low in toughness, results in the facesheet being peeled from the core material, possibly leading to a significant loss in structural integrity of the sandwich panel. In an incident during a test on a liquid hydrogen fuel tank of the X-33 prototype vehicle, the outer graphite/epoxy facesheet and honeycomb core became debonded from the inner facesheet along significant areas, leading to failure of the tank. As a consequence of the accident; significant efforts were made to characterize the toughness of the facesheet/core bond. Currently, the only standardized method available for assessing the quality of the facesheet/core interface is the climbing drum peel test (ASTM D1781). During this test a sandwich beam is removed from a panel and the lip of one of the facesheets is attached to a drum, as shown in Fig. 1. The drum is then rotated along the sandwich beam, causing the facesheet to peel from the core. This method has two major drawbacks. First, it is not possible to obtain quantitative fracture data from the test and so the results can only be used in a qualitative manner. Second, only sandwich structure with thin facesheets can be tested (to facilitate wrapping of the facesheet around the climbing drum). In recognition of the need for a more quantitative facesheet/core fracture test, several workers have devised experimental techniques for characterizing the toughness of the facesheet/core interface. In all of these cases, the tests are designed to yield a mode I-dominated fracture toughness of the facesheet/core interface in a manner similar to that used to determine mode I fracture toughness of composite laminates. In the current work, a modified double cantilever beam is used to measure the mode I-dominated fracture toughness of the interface in a sandwich consisting of glass/phenolic honeycomb core reinforced with graphite epoxy facesheets. Two specimen configurations were tested as shown in Fig 2. The first configuration consisted of reinforcing the facesheets with aluminum blocks (Fig. 2a). In the second configuration unreinforced specimens were tested (Fig. 2b). Climbing drum peel tests were also conducted to compare the fracture behavior observed between this test and the modified double cantilever beam. This paper outlines the test procedures and data reduction strategies used to compute fracture toughness values from the tests. The effect of specimen reinforcement on fracture toughness of the facesheet/core interface is discussed.

  6. Development of Quiet Honeycomb Panels

    NASA Technical Reports Server (NTRS)

    Palumbo, Daniel L.; Klos, Jacob

    2009-01-01

    Sandwich honeycomb composite panels are lightweight and strong, and, therefore, provide a reasonable alternative to the aluminum ring framelstringer architecture currently used for most aircraft airframes. The drawback to honeycomb panels is that they radiate noise into the aircraft cabin very efficiently provoking the need for additional sound treatment which adds weight and reduces the material's cost advantage. A series of honeycomb panels were made which incorporated different design strategies aimed at reducing the honeycomb panels' radiation efficiency while at the same time maintaining its strength. The majority of the desi gns were centered around the concept of creatin g areas of reduced stiffness in the panel by adding voids and recesses to the core. The effort culminated with a reinforced./recessed panel which had 6 dB higher transmission loss than the baseline solid core panel while maintaining comparable strength.

  7. 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.

  8. Ultrasonic, microwave, and millimeter wave inspection techniques for adhesively bonded stacked open honeycomb core composites

    NASA Astrophysics Data System (ADS)

    Thomson, Clint D.; Cox, Ian; Ghasr, Mohammad Tayeb Ahmed; Ying, Kuang P.; Zoughi, Reza

    2015-03-01

    Honeycomb sandwich composites are used extensively in the aerospace industry to provide stiffness and thickness to lightweight structures. A common fabrication method for thick, curved sandwich structures is to stack and bond multiple honeycomb layers prior to machining core curvatures. Once bonded, each adhesive layer must be inspected for delaminations and the presence of unwanted foreign materials. From a manufacturing and cost standpoint, it can be advantageous to inspect the open core prior to face sheet closeout in order to reduce end-article scrap rates. However, by nature, these honeycomb sandwich composite structures are primarily manufactured from low permittivity and low loss materials making detection of delamination and some of the foreign materials (which also are low permittivity and low loss) quite challenging in the microwave and millimeter wave regime. Likewise, foreign materials such as release film in adhesive layers can be sufficiently thin as to not cause significant attenuation in through-transmission ultrasonic signals, making them difficult to detect. This paper presents a collaborative effort intended to explore the efficacy of different non-contact NDI techniques for detecting flaws in a stacked open fiberglass honeycomb core panel. These techniques primarily included air-coupled through-transmission ultrasonics, single-sided wideband synthetic aperture microwave and millimeter-wave imaging, and lens-focused technique. The goal of this investigation has been to not only evaluate the efficacy of these techniques, but also to determine their unique advantages and limitations for evaluating parameters such as flaw type, flaw size, and flaw depth.

  9. Compression After Impact on Honeycomb Core Sandwich Panels with Thin Facesheets, Part 2: Analysis

    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 2, the subject of the current paper, is focused on the analysis, which corresponds to the CAI testings described in Part 1. 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 materials, which were identical with the exception of the density of the honeycomb core, were tested in Part 1. The results highlighted the need for analysis methods which taken into account multiple failure modes. A finite element model (FEM) is developed here, in Part 2. A commercial implementation of the Multicontinuum Failure Theory (MCT) for progressive failure analysis (PFA) in composite laminates, Helius:MCT, is included in this model. The inclusion of PFA in the present model provided a new, unique ability to account for multiple failure modes. In addition, significant impact damage detail is included in the model. A sensitivity study, used to assess the effect of each damage parameter on overall analysis results, is included in an appendix. Analysis results are compared to the experimental results for each of the 32 CAI sandwich panel specimens tested to failure. The failure of each specimen is predicted using the high-fidelity, physicsbased analysis model developed here, and the results highlight key improvements in the understanding of honeycomb core sandwich panel CAI failure. Finally, a parametric study highlights the strength benefits compared to mass penalty for various core densities.

  10. 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.

  11. Evaluation of the Transient Liquid Phase (TLP) Bonding Process for Ti3Al-Based Honeycomb Core Sandwich Structure

    NASA Technical Reports Server (NTRS)

    Bird, R. Keith; Hoffman, Eric K.

    1998-01-01

    The suitability of using transient liquid phase (TLP) bonding to fabricate honeycomb core sandwich panels with Ti-14Al-21Nb (wt%) titanium aluminide (T3Al) face sheets for high-temperature hypersonic vehicle applications was evaluated. Three titanium alloy honeycomb cores and one Ti3Al alloy honeycomb core were investigated. Edgewise compression (EWC) and flatwise tension (FWT) tests on honeycomb core sandwich specimens and tensile tests of the face sheet material were conducted at temperatures ranging from room temperature to 1500 F. EWC tests indicated that the honeycomb cores and diffusion bonded joints were able to stabilize the face sheets up to and beyond the face sheet compressive yield strength for all temperatures investigated. The specimens with the T3Al honeycomb core produced the highest FWT strengths at temperatures above 1000 F. Tensile tests indicated that TLP processing conditions resulted in decreases in ductility of the Ti-14Al-21Nb face sheets. Microstructural examination showed that the side of the face sheets to which the filler metals had been applied was transformed from equiaxed alpha2 grains to coarse plates of alpha2 with intergranular Beta. Fractographic examination of the tensile specimens showed that this transformed region was dominated by brittle fracture.

  12. Comparison of structural behavior of superplastically formed/diffusion-bonded sandwich structures and honeycomb core sandwich structures

    NASA Technical Reports Server (NTRS)

    Ko, W. L.

    1980-01-01

    A superplasticity formed/diffusion-bonded (SPF/DB) orthogonally corrugated core sandwich structure is discussed and its structural behavior is compared to that of a conventional honeycomb core sandwich structure. The stiffness and buckling characteristics of the two types of sandwich structures are compared under conditions of equal structural density. It is shown that under certain conditions, the SPF/DB orthogonally corrugated core sandwich structure is slightly more efficient than the optimum honeycomb core (square-cell core) sandwich structure. However, under different conditions, this effect can be reversed.

  13. Measuring Core/Facesheet Bond Toughness in Honeycomb Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.

    2006-01-01

    This study examines two test methods to evaluate the peel toughness of the skin to core debond of sandwich panels. The methods tested were the climbing drum (CD) peel test and the double cantilever beam (DCB) test. While the CD peel test is only intended for qualitative measurements, it is shown in this study that qualitative measurements can be performed and compare well with DCB test data. It is also shown that artificially stiffening the facesheets of a DCB specimen can cause the test to behave more like a flatwise tensile test than a peel test.

  14. 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.

  15. 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.

  16. Honeycomb-laminate composite structure

    NASA Technical Reports Server (NTRS)

    Gilwee, W. J., Jr.; Parker, J. A. (inventors)

    1977-01-01

    A honeycomb-laminate composite structure was comprised of: (1) a cellular core of a polyquinoxaline foam in a honeycomb structure, and (2) a layer of a noncombustible fibrous material impregnated with a polyimide resin laminated on the cellular core. A process for producing the honeycomb-laminate composite structure and articles containing the honeycomb-laminate composite structure is described.

  17. Elevated-Temperature Tests Under Static and Aerodynamic Conditions on Honeycomb-Core Sandwich Panels

    NASA Technical Reports Server (NTRS)

    Groen, Joseph M.; Johnson, Aldie E., Jr.

    1959-01-01

    Stainless-steel honeycomb-core sandwich panels which differed primarily in skin thicknesses were tested at elevated temperatures under static and aerodynamic conditions. The results of these tests were evaluated to determine the insulating effectiveness and structural integrity of the panels. The static radiant-heating tests were performed in front of a quartz-tube radiant heater at panel skin temperatures up to 1,5000 F. The aerodynamic tests were made in a Mach 1.4 heated blowdown wind tunnel. The tunnel temperature was augmented by additional heat supplied by a radiant heater which raised the panel surface temperature above 8000 F during air flow. Static radiant-heating tests of 2 minutes duration showed that all the panels protected the load-carrying structure about equally well. Thin-skin panels showed an advantage for this short-time test over thick-skin panels from a standpoint of weight against insulation. Permanent inelastic strains in the form of local buckles over each cell of the honeycomb core caused an increase in surface roughness. During the aero- dynamic tests all of the panels survived with little or no damage, and panel flutter did not occur.

  18. 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.

  19. MANUFACTURE OF ARBITRARY CROSS-SECTION COMPOSITE HONEYCOMB CORES BASED ON ORIGAMI TECHNIQUES

    E-print Network

    Pellegrino, Sergio

    Saito * Department of Mechanical and Biofunctional Systems Institute of Industrial Science, these foldable composites that are cured in corrugated shapes in autoclaves are folded into honeycomb shapes

  20. Fabrication and evaluation of enhanced diffusion bonded titanium honeycomb core sandwich panels with titanium aluminide face sheets

    NASA Technical Reports Server (NTRS)

    Hoffmann, E. K.; Bird, R. K.; Bales, T. T.

    1989-01-01

    A joining process was developed for fabricating lightweight, high temperature sandwich panels for aerospace applications using Ti-14Al-21Nb face sheets and Ti-3Al-2.5V honeycomb core. The process, termed Enhanced Diffusion Bonding (EDB), relies on the formation of a eutectic liquid through solid-state diffusion at elevated temperatures and isothermal solidification to produce joints in thin-gage titanium and titanium aluminide structural components. A technique employing a maskant on the honeycomb core was developed which permitted electroplating a controlled amount of EDB material only on the edges of the honeycomb core in order to minimize the structural weight and metallurgical interaction effects. Metallurgical analyses were conducted to determine the interaction effects between the EDB materials and the constituents of the sandwich structure following EDB processing. The initial mechanical evaluation was conducted with butt joint specimens tested at temperatures from 1400 - 1700 F. Further mechanical evaluation was conducted with EDB sandwich specimens using flatwise tension tests at temperatures from 70 - 1100 F and edgewise compression tests at ambient temperature.

  1. Buckling Analysis of a Honeycomb-Core Composite Cylinder with Initial Geometric Imperfections

    NASA Technical Reports Server (NTRS)

    Cha, Gene; Schultz, Marc R.

    2013-01-01

    Thin-walled cylindrical shell structures often have buckling as the critical failure mode, and the buckling of such structures can be very sensitive to small geometric imperfections. The buckling analyses of an 8-ft-diameter, 10-ft-long honeycomb-core composite cylinder loaded in pure axial compression is discussed in this document. Two loading configurations are considered configuration 1 uses simple end conditions, and configuration 2 includes additional structure that may more closely approximate experimental loading conditions. Linear eigenvalue buckling analyses and nonlinear analyses with and without initial geometric imperfections were performed on both configurations. The initial imperfections were introduced in the shell by applying a radial load at the midlength of the cylinder to form a single inward dimple. The critical bifurcation buckling loads are predicted to be 924,190 lb and 924,020 lb for configurations 1 and 2, respectively. Nonlinear critical buckling loads of 918,750 lb and 954,900 lb were predicted for geometrically perfect configurations 1 and 2, respectively. Lower-bound critical buckling loads for configurations 1 and 2 with radial perturbations were found to be 33% and 36% lower, respectively, than the unperturbed critical loads. The inclusion of the load introduction cylinders in configuration 2 increased the maximum bending-boundary-layer rotation up to 11%.

  2. Microsandwich honeycomb

    NASA Technical Reports Server (NTRS)

    Bhat, T. Balakrishna; Wang, Taylor G.; Gibson, Lorna J.

    1989-01-01

    Microsandwich honeycombs are honeycombs in which the cell walls are themselves sandwich structures. This article develops the idea of microsandwich honeycombs, outlining their design principles, fabrication techniques and properties.

  3. 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.

  4. Novel design of honeycombs using a seamless combination of auxetic and conventional cores toward phononic band gap engineering

    NASA Astrophysics Data System (ADS)

    Mukherjee, Sushovan; Scarpa, Fabrizio; Gopalakrishnan, S.

    2015-04-01

    A novel design for the geometric configuration of honeycombs using a seamless combination of auxetic and conventional cores-elements with negative and positive Possion ratios respectively, has been presented. The proposed design has been shown to generate a superior band gap property while retaining all major advantages of a purely conventional or purely auxetic honeycomb structure. Seamless combination ensures that joint cardinality is also retained. Several configurations involving different degree of auxeticity and different proportions auxetic and conventional elements have been analyzed. It has been shown that the preferred configurations open up wide and clean band gap at a significantly lower frequency ranges compared to their pure counterparts. In view of existence of band gaps being desired feature for the phononic applications, reported results might be appealing. Use of such design may enable superior vibration control as well. Proposed configurations can be made isovolumic and iso-weight giving designers a fairer ground of applying such configurations without significantly changing size and weight criteria.

  5. Ballistic Resistance of Honeycomb Sandwich Panels under In-Plane High-Velocity Impact

    PubMed Central

    Yang, Shu; Wang, Dong; Yang, Li-Jun

    2013-01-01

    The dynamic responses of honeycomb sandwich panels (HSPs) subjected to in-plane projectile impact were studied by means of explicit nonlinear finite element simulations using LS-DYNA. The HSPs consisted of two identical aluminum alloy face-sheets and an aluminum honeycomb core featuring three types of unit cell configurations (regular, rectangular-shaped, and reentrant hexagons). The ballistic resistances of HSPs with the three core configurations were first analyzed. It was found that the HSP with the reentrant auxetic honeycomb core has the best ballistic resistance, due to the negative Poisson's ratio effect of the core. Parametric studies were then carried out to clarify the influences of both macroscopic (face-sheet and core thicknesses, core relative density) and mesoscopic (unit cell angle and size) parameters on the ballistic responses of the auxetic HSPs. Numerical results show that the perforation resistant capabilities of the auxetic HSPs increase as the values of the macroscopic parameters increase. However, the mesoscopic parameters show nonmonotonic effects on the panels' ballistic capacities. The empirical equations for projectile residual velocities were formulated in terms of impact velocity and the structural parameters. It was also found that the blunter projectiles result in higher ballistic limits of the auxetic HSPs. PMID:24187526

  6. Ballistic resistance of honeycomb sandwich panels under in-plane high-velocity impact.

    PubMed

    Qi, Chang; Yang, Shu; Wang, Dong; Yang, Li-Jun

    2013-01-01

    The dynamic responses of honeycomb sandwich panels (HSPs) subjected to in-plane projectile impact were studied by means of explicit nonlinear finite element simulations using LS-DYNA. The HSPs consisted of two identical aluminum alloy face-sheets and an aluminum honeycomb core featuring three types of unit cell configurations (regular, rectangular-shaped, and reentrant hexagons). The ballistic resistances of HSPs with the three core configurations were first analyzed. It was found that the HSP with the reentrant auxetic honeycomb core has the best ballistic resistance, due to the negative Poisson's ratio effect of the core. Parametric studies were then carried out to clarify the influences of both macroscopic (face-sheet and core thicknesses, core relative density) and mesoscopic (unit cell angle and size) parameters on the ballistic responses of the auxetic HSPs. Numerical results show that the perforation resistant capabilities of the auxetic HSPs increase as the values of the macroscopic parameters increase. However, the mesoscopic parameters show nonmonotonic effects on the panels' ballistic capacities. The empirical equations for projectile residual velocities were formulated in terms of impact velocity and the structural parameters. It was also found that the blunter projectiles result in higher ballistic limits of the auxetic HSPs. PMID:24187526

  7. The structural behavior of a graphite-polymide honeycomb sandwich panel with quasi-isotropic face sheets and an orthotropic core

    NASA Technical Reports Server (NTRS)

    Hyer, M. W.; Hagaman, J. A.

    1979-01-01

    The results of a series of tests of graphite-polyimide honeycomb sandwich panels are presented. The panels were 1.22 m long, 0.508 m wide, and approximately 13.3 m thick. The face sheets were a T-300/PMR-15 fabric in a quasi-isotropic layup and were 0.279 mm thick. The core was Hexcel HRH 327-3/16 - 4.0 glass reinforced polyimide honeycomb, 12.7 mm thick. Three panels were used in the test: one was cut into smaller pieces for testing as beam, compression, and shear specimens; a second panel was used for plate bending tests; the third panel was used for in-plane stability tests. Presented are the experimental results of four point bending tests, short block compression tests, core transverse shear modulus, three point bending tests, vibration tests, plate bending tests, and panel stability tests. The results of the first three tests are used to predict the results of some of the other tests. The predictions and experimental results are compared, and the agreement is quite good.

  8. Piezoelectrically-induced guided wave propagation for health monitoring of honeycomb sandwich structures

    NASA Astrophysics Data System (ADS)

    Song, Fei

    Honeycomb sandwich structures have been widely used in marine and aerospace applications due to their high strength/stiffness-to-weight ratio. However, an excessive load or repeated loading in the core tends to induce debonding along the skin-core interface, threatening the integrity and safety of the whole structure. This dissertation focuses on development of guided wave strategies for health monitoring of honeycomb sandwich structures, based on a piezoelectric actuator/sensor network. The honeycomb sandwich panels, which are composed of aluminum alloy (T6061) skins and hexagonal-celled Nomex core, are specifically considered in the study. First, elastic wave propagation mechanism in honeycomb sandwich structures is numerically and experimentally investigated, based on a piezoelectric actuator/sensor system. Influences of cell geometry parameters upon wave propagation are also discussed. Some wave propagation characteristics, such as wave group velocity dispersion relation and mode tuning capabilities, in the honeycomb composite panels are experimentally characterized. Secondly, effects of skin-core debonding upon the leaky guided wave propagation in honeycomb sandwich structures are studied by the finite element simulation. An appropriate signal difference coefficient is defined to represent the differential features caused by debonding. By means of probability analysis of differential features of transmitted guided waves and the image fusion, the final image of the structure is constructed with improved detection precision. A multilevel sensor network strategy is proposed to detect multiple debondings in the honeycomb sandwich structure. Thirdly, an analytical model considering coupled piezo-elastodynamics is developed to quantitatively describe dynamic load transfer between a surface-bonded piezoelectric wafer actuator and a prestressed plate. The finite element method is used to evaluate the accuracy of the analytical prediction. Effects of prestresses on the characteristics of guided wave generation and propagation, such as time-of-flight, amplitude and wave tuning properties of guided wave modes, are analyzed, based on the developed model. Finally, to overcome the limitations of conventional guided wave methods, a baseline-free detection technique by using nonlinear acoustics is developed for debonding identification in honeycomb sandwich structures. The finite element analysis is performed to understand effects of the interaction of two debonded interfaces upon dynamic behavior of the sandwich structure. Specific experimental study is also conducted on the honeycomb sandwich panel to validate the concept. This dissertation study aims to broaden the scope of existing guided wave methods for debonding detection in honeycomb sandwich structures, and provide some insights for health monitoring of in-service structures.

  9. Probability of Detection Study on Impact Damage to Honeycomb Composite Structure using Thermographic Inspection

    NASA Technical Reports Server (NTRS)

    Hodge, Andrew J.; Walker, James L., II

    2008-01-01

    A probability of detection study was performed for the detection of impact damage using flash heating infrared thermography on a full scale honeycomb composite structure. The honeycomb structure was an intertank structure from a previous NASA technology demonstration program. The intertank was fabricated from IM7/8552 carbon fiber/epoxy facesheets and aluminum honeycomb core. The intertank was impacted in multiple locations with a range of impact energies utilizing a spherical indenter. In a single blind study, the intertank was inspected with thermography before and after impact damage was incurred. Following thermographic inspection several impact sites were sectioned from the intertank and cross-sectioned for microscopic comparisons of NDE detection and actual damage incurred. The study concluded that thermographic inspection was a good method of detecting delamination damage incurred by impact. The 90/95 confidence level on the probability of detection was close to the impact energy that delaminations were first observed through cross-sectional analysis.

  10. SPERT Destructive Test - I on Aluminum, Highly Enriched Plate Type Core

    ScienceCinema

    None

    2014-05-07

    SPERT - Special Power Excursion Reactor Tests Destructive Test number 1 On Aluminum, Highly Enriched Plate Type Core. A test studying the behavior of the reactor under destructive conditions on a light water moderated pool-type reactor with a plate-type core.

  11. 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: Received 25 February 2013 Received in revised form 6 May 2013 Accepted 30 May 2013 Available online 20 June bending resistance of sandwich panels relative to monolithic plates of equivalent areal density [1

  12. Numerical simulation of temperature field in horizontal core-filling continuous casting for copper cladding aluminum rods

    NASA Astrophysics Data System (ADS)

    Su, Ya-jun; Liu, Xin-hua; Wu, Yong-fu; Huang, Hai-you; Xie, Jian-xin

    2013-07-01

    The steady-state temperature field of horizontal core-filling continuous casting (HCFC) for producing copper cladding aluminum rods was simulated by finite element method to investigate the effects of key processing parameters on the positions of solid-liquid interfaces (SLIs) of copper and aluminum. It is found that mandrel tube length and mean withdrawing speed have significant effects on the SLI positions of both copper and aluminum. Aluminum casting temperature ( T Al) (1003-1123 K) and secondary cooling water flux (600-900 L·h-1) have little effect on the SLI of copper but cause the SLI of aluminum to move 2-4 mm. When T Al is in a range of 1043-1123 K, the liquid aluminum can fill continuously into the pre-solidified copper tube. Based on the numerical simulation, reasonable processing parameters were determined.

  13. Multistable grid and honeycomb shells

    E-print Network

    Loukaides, E. G.; Seffen, K. A.

    2015-01-10

    .M. (2011). On the thermally induced bistability of composite cylindrical shells for morphing structures. International Journal of Solids and Structures . Russell, B., Liu, T., Fleck, N. & Deshpande, V. (2011). Quasi-static three-point bending of carbon... fiber sandwich beams with square honeycomb cores. Journal of Ap- plied Mechanics , 78, 031008. Salamon, N.J. & Masters, C.B. (1995). Bifurcation in isotropic thinfilm/substrate plates. International Journal of Solids and Structures , 32, 473–481. Seffen...

  14. A novel method of testing the shear strength of thick honeycomb composites

    NASA Technical Reports Server (NTRS)

    Hodge, A. J.; Nettles, A. T.

    1991-01-01

    Sandwich composites of aluminum and glass/phenolic honeycomb core were tested for shear strength before and after impact damage. The assessment of shear strength was performed in two ways; by four point bend testing of sandwich beams and by a novel double lap shear (DLS) test. This testing technique was developed so smaller specimens could be used, thus making the use of common lab scale fabrication and testing possible. The two techniques yielded similar data. The DLS test gave slightly lower shear strength values of the two methods but were closer to the supplier's values for shear strength.

  15. Characterization and elimination of defects in metallic glass honeycomb

    NASA Astrophysics Data System (ADS)

    Mahadevan, Ganapathi Ranjan

    This work focuses on quantification and elimination of defects in the new class of amorphous metallic glass honeycombs (MGH) developed in 2009. A new lab scale method of manufacturing was devised to produce defect free MGH, and it has reduced cell wall misorientation from 15° to 1.5° and also yielded a more uniform cell geometry. A threefold improvement in the strength of MGH was observed with the use of this new manufacturing method. MG Honeycombs have exhibited 20% higher crush strength and 20% higher peak strength than Al honeycombs of higher relative density. The effect of cell axis misorientation on honeycomb strength related to the effect of inclined loads on honeycomb strength was studied using skewed aluminum honeycomb sections with different cell axis inclinations. A sigmoidal decrease in the strength of honeycombs with increasing loading angles was found. This research gives insight into the potential of Metallic Glass Honeycombs as structural materials. It also suggests the advantages expected for more precise automated mass production of the new material. Further, it helps in understanding the effect of inclined loads on honeycomb performance.

  16. Advanced radiator concepts utilizing honeycomb panel heat pipes (stainless steel)

    NASA Technical Reports Server (NTRS)

    Fleischman, G. L.; Tanzer, H. J.

    1985-01-01

    The feasibility of fabricating and processing moderate temperature range heat pipes in a low mass honeycomb sandwich panel configuration for highly efficient radiator fins for the NASA space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include: type of material, material and panel thicknesses, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. In addition, the overall performance of the honeycomb panel heat pipe was evaluated analytically.

  17. Controlled Release from Core-Shell Nanoporous Silica Particles for Corrosion Inhibition of Aluminum Alloys

    DOE PAGESBeta

    Jiang, Xingmao; Jiang, Ying-Bing; Liu, Nanguo; Xu, Huifang; Rathod, Shailendra; Shah, Pratik; Brinker, C. Jeffrey

    2011-01-01

    Cerium (Ce) corrosion inhibitors were encapsulated into hexagonally ordered nanoporous silica particles via single-step aerosol-assisted self-assembly. The core/shell structured particles are effective for corrosion inhibition of aluminum alloy AA2024-T3. Numerical simulation proved that the core-shell nanostructure delays the release process. The effective diffusion coefficient elucidated from release data for monodisperse particles in water was 1.0 × 10 ? 14 ?m 2 s for Ce 3+ compared to 2.5 × 10 ? 13 ?m 2 s for NaCl. The poremore »size, pore surface chemistry, and the inhibitor solubility are crucial factors for the application. Microporous hydrophobic particles encapsulating a less soluble corrosion inhibitor are desirable for long-term corrosion inhibition. « less

  18. General Method for the Synthesis of Ultrastable Core/Shell Quantum Dots by Aluminum Doping.

    PubMed

    Li, Zhichun; Yao, Wei; Kong, Long; Zhao, Yixin; Li, Liang

    2015-10-01

    Semiconductor quantum dots (QDs) have attracted extensive attention in various applications because of their unique optical and electronic properties. However, long-term photostability remains a challenge for their practical application. Here, we present a simple method to enhance the photostability of QDs against oxidation by doping aluminum into the shell of core/shell QDs. We demonstrate that Al in the coating shell can be oxidized to Al2O3, which can serve as a self-passivation layer on the surface of the core/shell QDs and effectively stop further photodegradation during long-term light irradiation. The prepared CdSe/CdS:Al QDs survived 24 h without significant degradation when they were subjected to intense illumination under LED light (450 nm, 0.35 W/cm(2)), whereas conventional CdSe/CdS QDs were bleached within 3 h. PMID:26389704

  19. Pre-Stressing Micron-Scale Aluminum Core-Shell Particles to Improve Reactivity

    NASA Astrophysics Data System (ADS)

    Levitas, Valery I.; McCollum, Jena; Pantoya, Michelle

    2015-01-01

    The main direction in increasing reactivity of aluminum (Al) particles for energetic applications is reduction in their size down to nanoscale. However, Al nanoparticles are 30-50 times more expensive than micron scale particles and possess safety and environmental issues. Here, we improved reactivity of Al micron scale particles by synthesizing pre-stressed core-shell structures. Al particles were annealed and quenched to induce compressive stresses in the alumina passivation shell surrounding Al core. This thermal treatment was designed based on predictions of the melt-dispersion mechanism (MDM); a theory describing Al particle reaction under high heating rate. For all anneal treatment temperatures, experimental flame propagation rates for Al combined with nanoscale copper oxide (CuO) are in quantitative agreement with the theoretical predictions based on the MDM. The best treatment increases flame rate by 36% and achieves 68% of that for the best Al nanoparticles.

  20. Pre-Stressing Micron-Scale Aluminum Core-Shell Particles to Improve Reactivity

    PubMed Central

    Levitas, Valery I.; McCollum, Jena; Pantoya, Michelle

    2015-01-01

    The main direction in increasing reactivity of aluminum (Al) particles for energetic applications is reduction in their size down to nanoscale. However, Al nanoparticles are 30–50 times more expensive than micron scale particles and possess safety and environmental issues. Here, we improved reactivity of Al micron scale particles by synthesizing pre-stressed core-shell structures. Al particles were annealed and quenched to induce compressive stresses in the alumina passivation shell surrounding Al core. This thermal treatment was designed based on predictions of the melt-dispersion mechanism (MDM); a theory describing Al particle reaction under high heating rate. For all anneal treatment temperatures, experimental flame propagation rates for Al combined with nanoscale copper oxide (CuO) are in quantitative agreement with the theoretical predictions based on the MDM. The best treatment increases flame rate by 36% and achieves 68% of that for the best Al nanoparticles. PMID:25597747

  1. Honeycomb vs. Foam: Evaluating a Potential Upgrade to ISS Module Shielding for Micrometeoroids and Orbital Debris

    NASA Technical Reports Server (NTRS)

    Ryan, Shannon; Hedman, Troy; Christiansen, Eric L.

    2009-01-01

    The presence of a honeycomb core in a multi-wall shielding configuration for protection against micrometeoroid and orbital debris (MMOD) particle impacts at hypervelocity is generally considered to be detrimental as the cell walls act to restrict fragment cloud expansion, creating a more concentrated load on the shield rear wall. However, mission requirements often prevent the inclusion of a dedicated MMOD shield, and as such, structural honeycomb sandwich panels are amongst the most prevalent shield types. Open cell metallic foams are a relatively new material with novel mechanical and thermal properties that have shown promising results in preliminary hypervelocity impact shielding evaluations. In this study, an ISS-representative MMOD shielding configuration has been modified to evaluate the potential performance enhancement gained through the substitution of honeycomb for open cell foam. The baseline shielding configuration consists of a double mesh outer layer, two honeycomb sandwich panels, and an aluminum rear wall. In the modified configuration the two honeycomb cores are replaced by open-cell foam. To compensate for the heavier core material, facesheets have been removed from the second sandwich panel in the modified configuration. A total of 19 tests on the double layer honeycomb and double layer foam configurations are reported. For comparable mechanical and thermal performance, the foam modifications were shown to provide a 15% improvement in critical projectile diameter at low velocities (i.e. 3 km/s) and a 3% increase at high velocities (i.e. 7 km/s) for normal impact. With increasing obliquity, the performance enhancement was predicted to increase, up to a 29% improvement at 60 (low velocity). Ballistic limit equations have been developed for the new configuration, and consider the mass of each individual shield component in order to maintain validity in the event of minor configuration modifications. Previously identified weaknesses of open cell foams for hypervelocity impact shielding such as large projectile diameters, low velocities, and high degrees of impact obliquity have all been investigated, and found to be negligible for the double-layer configuration.

  2. Flexible honeycomb structure can bend to fit compound curves

    NASA Technical Reports Server (NTRS)

    Carmody, R. J.

    1964-01-01

    For flexibility in forming a curved surface, a honeycomb configuration using multiple pleats has proved superior to the usual core structures. The partial pleats formed in individual cell walls permit movements to and from the central axis without tearing.

  3. The Definition of Quality of Honeycomb Structures

    NASA Astrophysics Data System (ADS)

    Sitalo, V. G.; Tykhyy, V. G.; Primakov, V. D.

    2002-01-01

    In the represented report the comprehensive approach to quality inspection of honeycomb structures is considered and substantiated to provide their high structural characteristics. The structures are intended for manufacturing micro satellite solar arrays. The investigated structures involve two skins of composite materials by a thickness from 0,1 to 0,3 mm and a filler by hexagonal honeycomb cells of aluminum alloy. It may be glued in a variety of ways: with a film glue or a glue deposited on end faces of cells. Variants and possibilities of nondestructive methods for quality inspection - holographic interferometer and infrared testing ones - are considered for various materials of skins and used glues. The various methods of loading the constructions is appreciated in order to get the required sensitivity of nondestructive besting methods. To provide the required structural properties in addition to the nondestructive testing the application of mechanical tests of honeycomb structure samples is substantiated. The kinds of mechanical tests are described and the results are given. The indicated approach provides the asked level of characteristics for honeycomb structures.

  4. Extruded ceramic honeycomb and method

    DOEpatents

    Day, J. Paul (Big Flats, NY)

    1995-04-04

    Extruded low-expansion ceramic honeycombs comprising beta-spodumene solid solution as the principal crystal phase and with less than 7 weight percent of included mullite are produced by compounding an extrusion batch comprising a lithium aluminosilicate glass powder and a clay additive, extruding a green honeycomb body from the batch, and drying and firing the green extruded cellular honeycomb to crystallize the glass and clay into a low-expansion spodumene ceramic honeycomb body.

  5. Thermal Inspection of Composite Honeycomb Structures

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph N.; Parker, F. Raymond

    2014-01-01

    Composite honeycomb structures continue to be widely used in aerospace applications due to their low weight and high strength advantages. Developing nondestructive evaluation (NDE) inspection methods are essential for their safe performance. Pulsed thermography is a commonly used technique for composite honeycomb structure inspections due to its large area and rapid inspection capability. Pulsed thermography is shown to be sensitive for detection of face sheet impact damage and face sheet to core disbond. Data processing techniques, using principal component analysis to improve the defect contrast, are presented. In addition, limitations to the thermal detection of the core are investigated. Other NDE techniques, such as computed tomography X-ray and ultrasound, are used for comparison to the thermography results.

  6. Flight service evaluation of two aluminum-brazed titanium spoilers

    NASA Technical Reports Server (NTRS)

    Boyer, R. R.

    1984-01-01

    The long-term service evaluation of two aluminum-brazed titanium (ABTi) honeycomb flight spoilers was concluded. The two spoilers had about 7.5 years of commercial flight experience on All Nippon Airways Model 737 aircraft. All Nippon Airways was selected because Japan has one of the most severe marine-industrial environments in the world. The results indicated that both flight spoilers still had the same load-carrying capability as when they were originally installed. No direct evidence of any corrosion was observed on either spoiler. Another significant accomplishment of this effort was the development of a braze design for efficiently distributing point loads from the fittings and skin into the honeycomb core.

  7. Superhydrophobic hierarchical honeycomb surfaces.

    PubMed

    Brown, P S; Talbot, E L; Wood, T J; Bain, C D; Badyal, J P S

    2012-09-25

    Two-dimensional hexagonally ordered honeycomb surfaces have been created by solvent casting polybutadiene films under controlled humidity. Subsequent CF(4) plasmachemical fluorination introduces cross-linking and surface texturing, leading to hierarchical surfaces with roughness on both the 10 ?m (honeycomb) and micrometer (texturing) length scales. For microliter droplets, these display high water contact angle values (>170°) in combination with low contact angle hysteresis (i.e., superhydrophobicity) while displaying bouncing of picoliter water droplets. In the case of picoliter droplets, it is found that surfaces which exhibit similar static contact angles can give rise to different droplet impact dynamics, governed by the underlying surface topography. These studies are of relevance to technological processes such as rapid cooling, delayed freezing, crop spraying, and inkjet printing. PMID:22966860

  8. Titanium Honeycomb Panel Testing

    NASA Technical Reports Server (NTRS)

    Richards, W. Lance; Thompson, Randolph C.

    1996-01-01

    Thermal-mechanical tests were performed on a titanium honeycomb sandwich panel to experimentally validate the hypersonic wing panel concept and compare test data with analysis. Details of the test article, test fixture development, instrumentation, and test results are presented. After extensive testing to 900 deg. F, non-destructive evaluation of the panel has not detected any significant structural degradation caused by the applied thermal-mechanical loads.

  9. 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.

  10. Heat Shielding Characteristics and Thermostructural Performance of a Superalloy Honeycomb Sandwich Thermal Protection System (TPS)

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    2004-01-01

    Heat-transfer, thermal bending, and mechanical buckling analyses have been performed on a superalloy "honeycomb" thermal protection system (TPS) for future hypersonic flight vehicles. The studies focus on the effect of honeycomb cell geometry on the TPS heat-shielding performance, honeycomb cell wall buckling characteristics, and the effect of boundary conditions on the TPS thermal bending behavior. The results of the study show that the heat-shielding performance of a TPS panel is very sensitive to change in honeycomb core depth, but insensitive to change in honeycomb cell cross-sectional shape. The thermal deformations and thermal stresses in the TPS panel are found to be very sensitive to the edge support conditions. Slight corrugation of the honeycomb cell walls can greatly increase their buckling strength.

  11. Optimized Non-Obstructive Particle Damping (NOPD) Treatment for Composite Honeycomb Structures

    NASA Technical Reports Server (NTRS)

    Panossian, H.

    2008-01-01

    Non-Obstructive Particle Damping (NOPD) technology is a passive vibration damping approach whereby metallic or non-metallic particles in spherical or irregular shapes, of heavy or light consistency, and even liquid particles are placed inside cavities or attached to structures by an appropriate means at strategic locations, to absorb vibration energy. The objective of the work described herein is the development of a design optimization procedure and discussion of test results for such a NOPD treatment on honeycomb (HC) composite structures, based on finite element modeling (FEM) analyses, optimization and tests. Modeling and predictions were performed and tests were carried out to correlate the test data with the FEM. The optimization procedure consisted of defining a global objective function, using finite difference methods, to determine the optimal values of the design variables through quadratic linear programming. The optimization process was carried out by targeting the highest dynamic displacements of several vibration modes of the structure and finding an optimal treatment configuration that will minimize them. An optimal design was thus derived and laboratory tests were conducted to evaluate its performance under different vibration environments. Three honeycomb composite beams, with Nomex core and aluminum face sheets, empty (untreated), uniformly treated with NOPD, and optimally treated with NOPD, according to the analytically predicted optimal design configuration, were tested in the laboratory. It is shown that the beam with optimal treatment has the lowest response amplitude. Described below are results of modal vibration tests and FEM analyses from predictions of the modal characteristics of honeycomb beams under zero, 50% uniform treatment and an optimal NOPD treatment design configuration and verification with test data.

  12. 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.

  13. A comparative investigation for the nondestructive testing of honeycomb structures by holographic interferometry and infrared thermography

    NASA Astrophysics Data System (ADS)

    Sfarra, S.; Ibarra-Castanedo, C.; Avdelidis, N. P.; Genest, M.; Bouchagier, L.; Kourousis, D.; Tsimogiannis, A.; Anastassopoulous, A.; Bendada, A.; Maldague, X.; Ambrosini, D.; Paoletti, D.

    2010-03-01

    The nondestructive testing (NDT) of honeycomb sandwich structures has been the subject of several studies. Classical techniques such as ultrasound testing and x-rays are commonly used to inspect these structures. Holographic interferometry (HI) and infrared thermography (IT) have shown to be interesting alternatives. Holography has been successfully used to detect debonding between the skin and the honeycomb core on honeycomb panels under a controlled environment. Active thermography has proven to effectively identify the most common types of defects (water ingress, debonding, crushed core, surface impacts) normally present in aeronautical honeycomb parts while inspecting large surfaces in a fast manner. This is very attractive for both the inspection during the manufacturing process and for in situ regular NDT assessment. A comparative experimental investigation is discussed herein to evaluate the performance of HI and IT for the NDT on a honeycomb panel with fabricated defects. The main advantages and limitations of both techniques are enumerated and discussed.

  14. Design Optimization and Analysis of a Composite Honeycomb Intertank

    NASA Technical Reports Server (NTRS)

    Finckenor, Jeffrey; Spurrier, Mike

    1998-01-01

    Intertanks, the structure between tanks of launch vehicles, are prime candidates for weight reduction of rockets. This paper discusses the optimization and detailed analysis of a 96 in (2.44 m) diameter, 77 in (1.85 m) tall intertank. The structure has composite face sheets and an aluminum honeycomb core. The ends taper to a thick built up laminate for a double lap bolted shear joint. It is made in 8 full length panels joined with bonded double lap joints. The nominal load is 4000 lb/in (7 x 10(exp 5) N/m). Optimization is by Genetic Algorithm and minimizes weight by varying C, core thickness, number and orientation of acreage and buildup plies, and the size, number and spacing of bolts. A variety of cases were run with populations up to 2000 and chromosomes as long as 150 bits. Constraints were buckling, face stresses (normal, shear, wrinkling and dimpling, bolt stress, and bolt hole stresses (bearing, net tension, wedge splitting, shear out and tension/shear out). Analysis is by a combination of theoretical solutions and empirical data. After optimization, a series of coupon tests were performed in conjunction with a rigorous analysis involving a variety of finite element models. The analysis and test resulted in several small changes to the optimized design. The intertank has undergone a 250,000 lb (1.1 x 10(exp 6) N) limit load test and been mated with a composite liquid hydrogen tank. The tank/intertank unit is being installed in a test stand where it will see 200 thermal/load cycles. Afterwards the intertank will be demated and loaded in compression to failure.

  15. Finite Element Development of Honeycomb Panel Configurations with Improved Transmission Loss

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Palumbo, Daniel L.; Klos, Jacob; Castle, William D.

    2006-01-01

    The higher stiffness-to-mass ratio of a honeycomb panel compared to a homogeneous panel results in a lower acoustic critical frequency. Above the critical frequency the panel flexural wave speed is acoustically fast and the structure becomes a more efficient radiator with associated lower sound transmission loss. Finite element models of honeycomb sandwich structures are presented featuring areas where the core is removed from the radiating face sheet disrupting the supersonic flexural and shear wave speeds that exist in the baseline honeycomb panel. These modified honeycomb panel structures exhibit improved transmission loss for a pre-defined diffuse field sound excitation. The models were validated by the sound transmission loss of honeycomb panels measured in the Structural Acoustic Loads and Transmission (SALT) facility at the NASA Langley Research Center. A honeycomb core panel configuration is presented exhibiting a transmission loss improvement of 3-11 dB compared to a honeycomb baseline panel over a frequency range from 170 Hz to 1000 Hz. The improved transmission loss panel configuration had a 5.1% increase in mass over the baseline honeycomb panel, and approximately twice the deflection when excited by a static force.

  16. Honeycomb spacer crush stength test results

    SciTech Connect

    Leader, D.R.

    1993-09-15

    This report discusses aluminum honeycomb spacers, which are used as an energy absorbent material in shipping packages for off site shipment of radioactive materials and which were ordered in two crush strengths, 1,000 psi and 2,000 psi for use in drop tests requested by the Packaging and Transportation group as part of the shipping container rectification process. Both the group as part of the shipping container rectification process. Both the vendor and the SRTC Materials Laboratory performed crush strength measurements on test samples made from the material used to fabricate the actual spacers. The measurements of crush strength made in the SRTC Materials Laboratory are within 100 psi of the measurements made by the manufacturer for all samples tested and all test measurements are within 10% of the specified crush strength, which is acceptable to the P&T group for the planned tests.

  17. A lightweight yet sound-proof honeycomb acoustic metamaterial

    NASA Astrophysics Data System (ADS)

    Sui, Ni; Yan, Xiang; Huang, Tai-Yun; Xu, Jun; Yuan, Fuh-Gwo; Jing, Yun

    2015-04-01

    In this letter, a class of honeycomb acoustic metamaterial possessing lightweight and yet sound-proof properties is designed, theoretically proven, and then experimentally verified. It is here reported that the proposed metamaterial having a remarkably small mass per unit area at 1.3 kg/m2 can achieve low frequency (<500 Hz) sound transmission loss (STL) consistently greater than 45 dB. Furthermore, the sandwich panel which incorporates the honeycomb metamaterial as the core material yields a STL that is consistently greater than 50 dB at low frequencies. The proposed metamaterial is promising for constructing structures that are simultaneously strong, lightweight, and sound-proof.

  18. Honeycomb Weathering of Limestone Formations

    USGS Multimedia Gallery

    Honeycomb weathering of sandstone located on the shores of Puget Sound occurs when expanding salt crystals break fragments of rock, creating a small hole that becomes larger as the process repeats itself over time....

  19. Aluminum/uranium fuel foaming/recriticality considerations for production reactor core-melt accidents

    SciTech Connect

    Hyder, M.L.; Ellison, P.G. ); Cronenberg, A.W. )

    1990-01-01

    Severe accident studies for the Savannah River production reactors indicate that if coherent fuel melting and relocation occur in the absence of target melting, in-vessel recriticality may be achieved. In this paper, fuel-melt/target interaction potential is assessed where fission gas-induced fuel foaming and melt attack on target material are evaluated and compared with available data. Models are developed to characterize foams for irradiated aluminum-based fuel. Predictions indicate transient foaming, the extent of which is governed by fission gas inventory, heating transient conditions, and bubble coalescence behavior. The model also indicates that metallic foams are basically unstable and will collapse, which largely depends on film tenacity and melt viscosity considerations. For high-burnup fuel, extensive foaming lasting tens of seconds is predicted, allowing molten fuel to contact and cause melt ablation of concentric targets. For low-burnup fuel, contact can not be assured. 9 refs., 4 figs., 4 tabs.

  20. Polymer optical waveguide composed of europium-aluminum-acrylate composite core for compact optical amplifier and laser

    NASA Astrophysics Data System (ADS)

    Mitani, Marina; Yamashita, Kenichi; Fukui, Toshimi; Ishigure, Takaaki

    2015-02-01

    We successfully fabricate polymer waveguides with Europium-Aluminum (Eu-Al) polymer composite core using the Mosquito method that utilizes a microdispenser for realizing a compact waveguide optical amplifiers and lasers. Rareearth (RE) ions are widely used as the gain medium for fiber lasers and optical fiber amplifiers. However, high concentration doping of rare-earth-ion leads to the concentration quenching resulting in observing less gain in optical amplification. For addressing the concentration quenching problem, a rare-earth metal (RE-M) polymer composite has been proposed by KRI, Inc. to be a waveguide core material. Actually, 10-wt% RE doping into organic polymer materials was already achieved. Hence, realization of compact and high-efficiency waveguide amplifiers and lasers have been anticipated using the RE-M polymer composite. In this paper, a microdispenser is adopted to fabricate a Eu-doped polymer waveguide. Then, it is experimentally confirmed that the low-loss waveguides are fabricated with a high reproducibility. Optical gain is estimated by measuring the amplified spontaneous emission using the variable stripe length method. The fabricated waveguide exhibits an optical gain as high as 7.1 dB/cm at 616-nm wavelength.

  1. Method of fabricating a honeycomb structure

    DOEpatents

    Holleran, L.M.; Lipp, G.D.

    1999-08-03

    A method of fabricating a monolithic honeycomb structure product involves shaping a first mixture of raw materials and a binder into a green honeycomb, extruding a second mixture of raw materials and a binder into one or more green members that each define an opening extending longitudinally therethrough. The raw materials of the second mixture are compatible with the raw materials of the first mixture. The green honeycomb and member(s) are dried. The binders of the green honeycomb and member(s) are softened at the surfaces that are to be bonded. The green member(s) is inserted into the honeycomb and bonded to the honeycomb to form an assembly thereof, which is then dried and fired to form a unified monolithic honeycomb structure. The insertion is best carried out by mounting a member in the shape of a tube on a mandrel, and inserting the mandrel into the honeycomb opening to bond the tube to the honeycomb. 7 figs.

  2. Method of fabricating a honeycomb structure

    DOEpatents

    Holleran, Louis M. (Big Flats, NY); Lipp, G. Daniel (Fort Collins, CO)

    1999-01-01

    A method of fabricating a monolithic honeycomb structure product involves shaping a first mixture of raw materials and a binder into a green honeycomb, extruding a second mixture of raw materials and a binder into one or more green members that each define an opening extending longitudinally therethrough. The raw materials of the second mixture are compatible with the raw materials of the first mixture. The green honeycomb and member(s) are dried. The binders of the green honeycomb and member(s) are softened at the surfaces that are to be bonded. The green member(s) is inserted into the honeycomb and bonded to the honeycomb to form an assembly thereof, which is then dried and fired to form a unified monolithic honeycomb structure. The insertion is best carried out by mounting a member in the shape of a tube on a mandrel, and inserting the mandrel into the honeycomb opening to bond the tube to the honeycomb.

  3. Method of fabricating lightweight honeycomb structures

    NASA Technical Reports Server (NTRS)

    Goela, Jitendra S. (Inventor); Pickering, Michael (Inventor); Taylor, Raymond L. (Inventor)

    1992-01-01

    A process is disclosed for fabricating lightweight honeycomb type structures out of material such as silicon carbide (SiC) and silicon (S). The lightweight structure consists of a core to define the shape and size of the structure. The core is coated with an appropriate deposit such as SiC or Si to give the lightweight structure strength and stiffness and for bonding the lightweight structure to another surface. The core is fabricated from extremely thin ribs of appropriately stiff and strong material such as graphite. First, a graphite core consisting of an outer hexagonal cell with six inner triangular cells is constructed from the graphite ribs. The graphite core may be placed on the back-up side of a SiC faceplate and then coated with SiC to produce a monolithic structure without the use of any bonding agent. Cores and methods for the fabrication thereof in which the six inner triangular cells are further divided into a plurality of cells are also disclosed.

  4. Core polarization for the electric quadrupole moment of neutron-rich Aluminum isotopes

    E-print Network

    Kenichi Yoshida

    2009-02-18

    The core polarization effect for the electric quadrupole moment of the neutron-rich $^{31}$Al, $^{33}$Al and $^{35}$Al isotopes in the vicinity of the island of inversion are investigated by means of the microscopic particle-vibration coupling model in which the Skyrme Hartee-Fock-Bogoliubov and quasiparticle-random-phase approximation are used to calculate the single-quasiparticle wave functions and the excitation modes. It is found that the polarization charge for the proton $1d_{5/2}$ hole state in $^{33}$Al is quite sensitive to coupling to the neutrons in the $pf$-shell associated with the pairing correlations, and that the polarization charge in $^{35}$Al becomes larger due to the stronger collectivity of the low-lying quadrupole vibrational mode in the neighboring $^{36}$Si nucleus.

  5. Surface deformation monitoring and reconstruction of honeycomb structure based on FBG sensors

    NASA Astrophysics Data System (ADS)

    Liu, Shulin; Lu, Jiyun; Zheng, Zhaoyu

    2015-07-01

    Honeycomb structure with high stiffness and light weight is expected to be more applied in the field of morphing wing. We propose a surface reconstruction algorithm based on FBG sensors to reconstruct the surface deformation of honeycomb structure real-timely and rapidly. When flexible honeycomb cores are driven by SMA actuators, the surface curvature monitored by FBG sensing array can be inferred from the changes of central wavelength. According to the surface reconstruction algorithm we proposed, the surface shape can be reconstructed. Composite single-row honeycomb structure specimen consisting of 8 cores, whose cell walls length and thickness is 8mm and 2mm respectively, is bended by electrified SMA actuators into the new steady shape. The experiment shows that the reconstructed surface shape has great agreement with the visual recording surface shape and the error is 5.76% on average.

  6. Millimeter Wave Holographical Inspection of Honeycomb Composites

    NASA Technical Reports Server (NTRS)

    Case, J. T.; Kharkovsky, S.; Zoughi, R.; Stefes, G.; Hepburn, Frank L.; Hepburn, Frank L.

    2007-01-01

    Multi-layered composite structures manufactured with honeycomb, foam or balsa wood cores are finding increasing utility in a variety of aerospace, transportation, and infrastructure applications. Due to the low conductivity and inhomogeneity associated with these composites standard nondestructive testing (NDT) methods are not always capable of inspecting their interior for various defects caused during the manufacturing process or as a result of in-service loading. On the contrary, microwave and millimeter wave NDT methods are well-suited for inspecting these structures since signals at these frequencies readily penetrate through these structures and reflect from different interior boundaries revealing the presence of a wide range of defects such as disbond, delamination, moisture and oil intrusion, impact damage, etc. Millimeter wave frequency spectrum spans 30 GHz - 300 GHz with corresponding wavelengths of 10 - 1 mm. Due to the inherent short wavelengths at these frequencies, one can produce high spatial resolution images of these composites either using real-antenna focused or synthetic-aperture focused methods. In addition, incorporation of swept-frequency in the latter method (i.e., holography) results in high-resolution three-dimensional images. This paper presents the basic steps behind producing such images at millimeter wave frequencies and the results of two honeycomb composite panels are demonstrated at Q-band (33-50 GHz). In addition, these results are compared to previous results using X-ray computed tomography.

  7. A study of PV/T collector with honeycomb heat exchanger

    NASA Astrophysics Data System (ADS)

    Hussain, F.; Othman, M. Y. H.; Yatim, B.; Ruslan, H.; Sopian, K.; Ibarahim, Z.

    2013-11-01

    This paper present a study of a single pass photovoltaic/thermal (PV/T) solar collector combined with honeycomb heat exchanger. A PV/T system is a combination of photovoltaic panel and solar thermal components in one integrated system. In order to enhance the performance of the system, a honeycomb heat exchanger is installed horizontally into the channel located under the PV module. Air is used as the heat remover medium. The system is tested with and without the honeycomb at irradiance of 828 W/m2 and mass flow rate spanning from 0.02 kg/s to 0.13 kg/s. It is observed that the aluminum honeycomb is capable of enhancing the thermal efficiency of the system efficiently. At mass flow rate of 0.11 kg/s, the thermal efficiency of the system without honeycomb is 27% and with honeycomb is 87 %. Throughout the range of the mass flow rate, the electrical efficiency of the PV module improved by 0.1 %. The improved design is suitable to be further investigated as solar drying system and space heating.

  8. Design data for brazed Rene 41 honeycomb sandwich

    NASA Technical Reports Server (NTRS)

    Hepler, A. K.; Arnquist, J.; Koetje, E. L.; Esposito, J. J.; Lindsay, V. E. J.; Swegle, A. R.

    1981-01-01

    Strength data, creep data and residual strength data after cyclic thermal exposure were obtained at temperatures from 78 K to 1144 K (-320 F to 1600 F). The influences of face thickness, core depth, core gage, cell size and thermal/stress exposure conditions on the mechanical design properties were investigated. A braze alloy and process was developed that is adequate to fully develop the strength of the honeycomb core while simultaneously solution treating and aging the Rene 41 fact sheets. New test procedures and test specimen configurations were developed to avoid excessive thermal stresses during cyclic thermal exposure.

  9. Impact-limiting materials characterization. [Structural and thermal testing of Al honeycombs and polyurethane foams

    SciTech Connect

    Glass, R. E.; Duffey, T. A.; McConnell, P.

    1991-01-01

    Goal in the design of an impact limiter (foams or honeycombs) for packaging of radioactive materials is to minimize the deceleration loads during a drop onto an unyielding target, and to reduce the effects of a fire. Methods are being developed for selecting impact-limiting materials. Figures of merit have been developed for screening both structural and thermal response; they have been applied to aluminum honeycombs and polyurethane foams. Three figures of merit are presented for the structural response, one figure for the thermal response (minimize the heat flux into the containment boundary). 11 figs., 6 refs. (DLC)

  10. Elastic wave propagation in hexagonal honeycomb sandwich composite by using piezoelectric actuators/sensors

    NASA Astrophysics Data System (ADS)

    Huang, G. L.; Song, F.; Kim, J.

    2009-03-01

    Honeycomb composite structures have been widely used in aerospace and aeronautic industries due to their unique characteristics. Due to the complex nature of honeycomb composite with the celled core, structural health monitoring (SHM) of honeycomb composite panels inherently imposes many challenges, which requires a detailed knowledge of dynamic elastic responses of such complex structures in a broad frequency domain. This paper gives numerical and experimental analyses of elastic wave propagation phenomena in sandwich panels with a honeycomb core, especially when the frequency domain of interest is relative high. Numerical simulation based on the Finite Element (FE) method is first performed to investigate wave generation and reception using piezoelectric actuators/sensors. The effectiveness of homogenized core model is discussed, compared with the dynamic responses based on honeycomb celled core model. The reliability of the simulated wave will be verified with the experimental results. Specific attention will be paid on core effects on group wave velocity. This research will establish a solid theoretical foundation for the future study of the structural health monitoring in the composites.

  11. Development of NDE to monitor bond degradation in aircraft honeycomb components

    SciTech Connect

    Bowles, Susan J.; Scala, Christine M.

    1999-12-02

    This paper presents results of recent research at DSTO Aeronautical and Maritime Research Laboratory to develop NDE techniques to assess bond degradation in metal-skin honeycomb and composite skin honeycomb control surfaces. In particular, it covers the detection of fillet bond failure where the honeycomb core and adhesive separate. Realistic fillet bond failure specimens, one of which had only 20% of the good bond strength, were generated by the application of spray-release agent to the honeycomb. 20MHz ultrasonic pulse-echo imaging was successfully used to detect fillet bond failure in these specimens. This technique was successful in detecting defined areas of fillet bond failure for a range of skin type and thickness Promising results were also obtained for the application to actual components, whilst also highlighting effects due to the presence of repairs. Further work will involve the evaluation of a range of other NDE methods to the detection and sizing of fillet bond failure.

  12. Load-dependent Optimization of Honeycombs for Sandwich Components - New Possibilities by Using Additive Layer Manufacturing

    NASA Astrophysics Data System (ADS)

    Riss, Fabian; Schilp, Johannes; Reinhart, Gunther

    Due to their feasible geometric complexity, additive layer manufacturing (ALM) processes show a highpotential for the production of lightweight components.Therefore, ALM processes enable the realization of bionic-designedcomponents like honeycombs, which are optimized depending upon load and outer boundary conditions.This optimization is based on a closed-loop, three-steps methodology: At first, each honeycomb is conformed to the surface of the part. Secondly, the structure is optimizedfor lightweight design.It is possible to achieve a homogeneous stress distribution in the part by varying the wall thickness, honeycombdiameter and the amount of honeycombs, depending on the subjected stresses and strains. At last, the functional components like threads or bearing carriers are integrated directly into the honeycomb core.Using all these steps as an iterative process, it is possible to reduce the mass of sandwich components about 50 percent compared to conventional approaches.

  13. Update on the 6.5 meter Borosilicate Honeycomb Mirror

    NASA Astrophysics Data System (ADS)

    Angel, J. R. P.; Hill, J. M.; Woolf, N. J.

    1992-12-01

    In April 1992 the University of Arizona Mirror Lab successfully cast the first U.S. telescope mirror blank that exceeds in size the Hale telescope mirror cast in 1935. The new blank goes well beyond the simple ribbed form of the Hale casting in its use of a honeycomb sandwich structure to reduce weight, enhance stiffness and control thermal distortion. The blank weighs 10 tons, less than the 5 m and most 4 m blanks, despite its 72 cm edge thickness. Chunks of Ohara E6 borosilicate glass were melted at 1180 C over 1020 ceramic cores to form the internal honeycomb. Wind-induced distortion, a serious issue for large telescopes aiming at matching the best atmospheric seeing, is eliminated because of the high stiffness. The honeycomb blank is an order of magnitude stiffer than the same mass of glass in a meniscus blank. Similarly mirror seeing, often a limitation when seeing is half an arcsecond or better, is eliminated by ventilation of the very open structure. Ventilation of the honeycomb with ambient air allows the mirror to track the nighttime temperature with a time constant of 30 -- 40 minutes. After three months of cooling and annealing, the furnace was opened in June 1992. At the time of this writing, the blank is about to be lifted for removal of the internal mold parts that form the honeycomb structure in the one-piece casting. Optical finishing of the F/1.25 parabolic surface by diamond generating and stressed lap polishing will begin in 1993.

  14. Structural Physics of Bee Honeycomb

    NASA Astrophysics Data System (ADS)

    Kaatz, Forrest; Bultheel, Adhemar; Egami, Takeshi

    2008-03-01

    Honeybee combs have aroused interest in the ability of honeybees to form regular hexagonal geometric constructs since ancient times. Here we use a real space technique based on the pair distribution function (PDF) and radial distribution function (RDF), and a reciprocal space method utilizing the Debye-Waller Factor (DWF) to quantify the order for a range of honeycombs made by Apis mellifera. The PDFs and RDFs are fit with a series of Gaussian curves. We characterize the order in the honeycomb using a real space order parameter, OP3, to describe the order in the combs and a two-dimensional Fourier transform from which a Debye-Waller order parameter, u, is derived. Both OP3 and u take values from [0, 1] where the value one represents perfect order. The analyzed combs have values of OP3 from 0.33 to 0.60 and values of u from 0.83 to 0.98. RDF fits of honeycomb histograms show that naturally made comb can be crystalline in a 2D ordered structural sense, yet is more `liquid-like' than cells made on `foundation' wax. We show that with the assistance of man-made foundation wax, honeybees can manufacture highly ordered arrays of hexagonal cells.

  15. Berry curvature of interacting bosons in a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Li, Yun; Sengupta, Pinaki; Batrouni, George G.; Miniatura, Christian; Grémaud, Benoît.

    2015-10-01

    We consider soft-core bosons with on-site interaction loaded in the honeycomb lattice with different site energies for the two sublattices. Using both a mean-field approach and quantum Monte Carlo simulations, we show that the topology of the honeycomb lattice results in a nonvanishing Berry curvature for the band structure of the single-particle excitations of the system. This Berry curvature induces an anomalous Hall effect when driving the system out of equilibrium. It is seen by studying the time evolution of a wave packet, namely, a superfluid ground state in a harmonic trap, subjected either to a constant force (Bloch oscillations) or to a sudden shift of the trap center.

  16. Hexagonal honeycomb foams Foams out of mechanical equilibrium

    E-print Network

    Cox, Simon

    Hexagonal honeycomb foams Foams out of mechanical equilibrium Foams out of physicochemical equilibrium Dissipation Mechanisms in Bubble Scale Foam Rheology Departures from Princen's Sheared Honeycomb P, Embley, Oguey Dissipation Mechanisms #12;Hexagonal honeycomb foams Foams out of mechanical equilibrium

  17. Demonstration of Minimally Machined Honeycomb Silicon Carbide Mirrors

    NASA Technical Reports Server (NTRS)

    Goodman, William

    2012-01-01

    Honeycomb silicon carbide composite mirrors are made from a carbon fiber preform that is molded into a honeycomb shape using a rigid mold. The carbon fiber honeycomb is densified by using polymer infiltration pyrolysis, or through a reaction with liquid silicon. A chemical vapor deposit, or chemical vapor composite (CVC), process is used to deposit a polishable silicon or silicon carbide cladding on the honeycomb structure. Alternatively, the cladding may be replaced by a freestanding, replicated CVC SiC facesheet that is bonded to the honeycomb. The resulting carbon fiber-reinforced silicon carbide honeycomb structure is a ceramic matrix composite material with high stiffness and mechanical strength, high thermal conductivity, and low CTE (coefficient of thermal expansion). This innovation enables rapid, inexpensive manufacturing. The web thickness of the new material is less than 1 millimeter, and core geometries tailored. These parameters are based on precursor carbon-carbon honeycomb material made and patented by Ultracor. It is estimated at the time of this reporting that the HoneySiC(Trademark) will have a net production cost on the order of $38,000 per square meter. This includes an Ultracor raw material cost of about $97,000 per square meter, and a Trex silicon carbide deposition cost of $27,000 per square meter. Even at double this price, HoneySiC would beat NASA's goal of $100,000 per square meter. Cost savings are estimated to be 40 to 100 times that of current mirror technologies. The organic, rich prepreg material has a density of 56 kilograms per cubic meter. A charred carbon-carbon panel (volatile organics burnt off) has a density of 270 kilograms per cubic meter. Therefore, it is estimated that a HoneySiC panel would have a density of no more than 900 kilograms per cubic meter, which is about half that of beryllium and about onethird the density of bulk silicon carbide. It is also estimated that larger mirrors could be produced in a matter of weeks. Each cell is completely uniform, maintaining the shape of the inserted mandrel. Furthermore, the layup creates pressure that insures node bond strength. Each node is a composite laminate using only the inherent resin system to form the bond. This contrasts starkly with the other known method of producing composite honeycomb, in which individual corrugations are formed, cured, and then bonded together in a secondary process. By varying the size of the mandrels within the layup, varying degrees of density can be achieved. Typical sizes are 3/8 and 3/16 in. (approximately 10 and 5 millimeters). Cell sizes up to 1 in. (approximately 25 millimeters) have been manufactured. Similarly, the shape of the core can be altered for a flexible honeycomb structure.

  18. Constraints on formation processes of two coarse-grained calcium- aluminum-rich inclusions: a study of mantles, islands and cores

    USGS Publications Warehouse

    Meeker, G.P.

    1995-01-01

    Many coarse-grained calcium- aluminum-rich inclusions (CAIs) contain features that are inconsistent with equilibrium liquid crystallization models of origin. Spinel-free islands (SFIs) in spinel-rich cores of Type B CAIs are examples of such features. One model previously proposed for the origin of Allende 5241, a Type B1 CAI containing SFIs, involves the capture and assimilation of xenoliths by a liquid droplet in the solar nebula (El Goresy et al, 1985; MacPherson et al 1989). This study reports new textural and chemical zoning data from 5241 and identifies previously unrecognized chemical zoning patterns in the melilite mantle and in a SFI. -from Author

  19. Edge states in honeycomb structures

    E-print Network

    Charles L. Fefferman; James P. Lee-Thorp; Michael I. Weinstein

    2015-06-28

    An edge state is a time-harmonic solution of a conservative wave system, e.g. Schr\\"odinger, Maxwell, which is propagating (plane-wave-like) parallel to, and localized transverse to, a line-defect or "edge." Topologically protected edge states are edge states which are stable against spatially localized (even strong) deformations of the edge. First studied in the context of the quantum Hall effect, protected edge states have attracted huge interest due to their role in the field of topological insulators. Theoretical understanding of topological protection has mainly come from discrete (tight-binding) models and direct numerical simulation. In this paper we consider a rich family of continuum PDE models for which we rigorously study regimes where topologically protected edge states exist. Our model is a class of Schroedinger operators on R^2 with a background two-dimensional honeycomb potential perturbed by an "edge-potential." The edge potential is a domain-wall interpolation, transverse to a prescribed "rational" edge, between two distinct periodic structures. General conditions are given for the bifurcation of a branch of topologically protected edge states from Dirac points of the background honeycomb structure. The bifurcation is seeded by the zero mode of a one-dimensional effective Dirac operator. A key condition is a spectral no-fold condition for the prescribed edge. We then use this result to prove the existence of topologically protected edge states along zigzag edges of certain honeycomb structures. Our results are consistent with the physics literature and appear to be the first rigorous results on the existence of topologically protected edge states for continuum 2D PDE systems. We also show that the family of Hamiltonians we study contains cases where zigzag edge states exist, but which are not topologically protected.

  20. Seal Leakages for Honeycomb or Smooth Configurations

    NASA Technical Reports Server (NTRS)

    Athavale, Mahesh M.; Hendricks, R. C.

    1997-01-01

    Three dimensional-CFD simulations were attempted to analyze the flow field in a honeycomb flat plate tester. This discussion reviews some of the numerical difficulties and relations, including those relating the honeycombs to labyrinth throttles and the consistency of selected seal and tester data sets.

  1. 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

    material (UMAT) subroutine in ABAQUS FE code is utilized to incorporate the viscoelastic constitutive model for the foam core. Analytical models and experimental data available in the literature are used to verify the results obtained from the FE analysis...

  2. Oxidation of hydrogen isotopes over honeycomb catalysts

    NASA Astrophysics Data System (ADS)

    Munakata, Kenzo; Wajima, Takaaki; Hara, Keisuke; Wada, Kohei; Shinozaki, Yohei; Katekari, Kenichi; Mochizuki, Kazuhiro; Tanaka, Masahiro; Uda, Tatsuhiko

    2011-10-01

    In the process of development of D-T fusion power reactors, recovery of tritium released into the last confinement system would be a key issue related to safety. If an accidental leakage of tritium takes place in a fusion power plant, a large volume of air should be detritiated with an air cleanup system (ACS). In ACS, tritium gas is converted to tritiated water vapor with a catalyst bed, and then which is recovered with an adsorption bed. In this study, the authors examined the applicability of honeycomb-type catalysts to ACS. A screening test of catalysts for oxidation of hydrogen and deuterium was performed using various honeycomb-type and pebble-type catalysts. Experimental results reveal that a honeycomb-type catalyst possesses a high oxidation performance for oxidation of hydrogen isotopes. Furthermore, the isotope effect on the oxidation of hydrogen isotopes over the honeycomb-type catalyst was thoroughly examined and quantified using tritium.

  3. Guided wave propagation in honeycomb sandwich structures using a piezoelectric actuator/sensor system

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    Due to the complex nature of such composite structures, an understanding of the guided wave propagation mechanism in honeycomb composite panels with different frequencies inherently imposes many challenges. In this paper, a numerical simulation is first conducted to investigate the wave propagation mechanism in honeycomb sandwich structures using piezoelectric actuators/sensors. In contrast to most of the previous work, elastic wave responses based on the real geometry of the honeycomb core are obtained by using the finite element method (FEM). Based on the simulation, the global guided waves in the composite can be observed when the loading frequency is low and the leaky guided waves in the skin panel are found when the loading frequency is sufficiently high. The applicability of the homogenization technique for a celled core is discussed. The effects of cell geometry on the wave propagation are also demonstrated. Experimental testing is finally conducted to validate the results of numerical simulation and very good agreement is observed. Specifically, some guided wave propagation characteristics such as group velocity dispersion and mode tuning capabilities with the presence of a honeycomb core are discussed.

  4. Ceramic honeycomb structures and the method thereof

    NASA Technical Reports Server (NTRS)

    Riccitiello, Salvatore R. (inventor); Cagliostro, Domenick E. (inventor)

    1987-01-01

    The subject invention pertains to a method of producing an improved composite-composite honeycomb structure for aircraft or aerospace use. Specifically, the subject invention relates to a method for the production of a lightweight ceramic-ceramic composite honeycomb structure, which method comprises: (1) pyrolyzing a loosely woven fabric/binder having a honeycomb shape and having a high char yield and geometric integrity after pyrolysis at between about 700 and 1,100 C; (2) substantially evenly depositing at least one layer of ceramic material on the pyrolyzed fabric/binder of step (1); (3) recovering the coated ceramic honeycomb structure; (4) removing the pyrolyzed fabric/binder of the structure of step (3) by slow pyrolysis at between 700 and 1000 C in between about a 2 to 5% by volume oxygen atmosphere for between about 0.5 and 5 hr.; and (5) substantially evenly depositing on and within the rigid hollow honeycomb structure at least one additional layer of the same or a different ceramic material by chemical vapor deposition and chemical vapor infiltration. The honeycomb shaped ceramic articles have enhanced physical properties and are useful in aircraft and aerospace uses.

  5. Design and fabrication of a radiative actively cooled honeycomb sandwich structural panel for a hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Ellis, D. A.; Pagel, L. L.; Schaeffer, D. M.

    1978-01-01

    The panel assembly consisted of an external thermal protection system (metallic heat shields and insulation blankets) and an aluminum honeycomb structure. The structure was cooled to temperature 442K (300 F) by circulating a 60/40 mass solution of ethylene glycol and water through dee shaped coolant tubes nested in the honeycomb and adhesively bonded to the outer skin. Rene'41 heat shields were designed to sustain 5000 cycles of a uniform pressure of + or - 6.89kPa (+ or - 1.0 psi) and aerodynamic heating conditions equivalent to 136 kW sq m (12 Btu sq ft sec) to a 422K (300 F) surface temperature. High temperature flexible insulation blankets were encased in stainless steel foil to protect them from moisture and other potential contaminates. The aluminum actively cooled honeycomb sandwich structural panel was designed to sustain 5000 cycles of cyclic in-plane loading of + or - 210 kN/m (+ or - 1200 lbf/in.) combined with a uniform panel pressure of + or - 6.89 kPa (?1.0 psi).

  6. 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

  7. Synthetic magnetic fluxes on the honeycomb lattice

    SciTech Connect

    Gorecka, Agnieszka; Gremaud, Benoit; Miniatura, Christian

    2011-08-15

    We devise experimental schemes that are able to mimic uniform and staggered magnetic fluxes acting on ultracold two-electron atoms, such as ytterbium atoms, propagating in a honeycomb lattice. The atoms are first trapped into two independent state-selective triangular lattices and then further exposed to a suitable configuration of resonant Raman laser beams. These beams induce hops between the two triangular lattices and make atoms move in a honeycomb lattice. Atoms traveling around each unit cell of this honeycomb lattice pick up a nonzero phase. In the uniform case, the artificial magnetic flux sustained by each cell can reach about two flux quanta, thereby realizing a cold-atom analog of the Harper model with its notorious Hofstadter's butterfly structure. Different condensed-matter phenomena such as the relativistic integer and fractional quantum Hall effects, as observed in graphene samples, could be targeted with this scheme.

  8. Synthetic magnetic fluxes on the honeycomb lattice

    E-print Network

    Agnieszka Górecka; Benoît Grémaud; Christian Miniatura

    2011-05-18

    We devise experimental schemes able to mimic uniform and staggered magnetic fluxes acting on ultracold two-electron atoms, such as ytterbium atoms, propagating in a honeycomb lattice. The atoms are first trapped into two independent state-selective triangular lattices and are further exposed to a suitable configuration of resonant Raman laser beams. These beams induce hops between the two triangular lattices and make atoms move in a honeycomb lattice. Atoms traveling around each unit cell of this honeycomb lattice pick up a nonzero phase. In the uniform case, the artificial magnetic flux sustained by each cell can reach about two flux quanta, thereby realizing a cold atom analogue of the Harper model with its notorious Hofstadter's butterfly structure. Different condensed-matter phenomena such as the relativistic integer and fractional quantum Hall effects, as observed in graphene samples, could be targeted with this scheme.

  9. Vibroacoustic Model Validation for a Curved Honeycomb Composite Panel

    NASA Technical Reports Server (NTRS)

    Buehrle, Ralph D.; Robinson, Jay H.; Grosveld, Ferdinand W.

    2001-01-01

    Finite element and boundary element models are developed to investigate the vibroacoustic response of a curved honeycomb composite sidewall panel. Results from vibroacoustic tests conducted in the NASA Langley Structural Acoustic Loads and Transmission facility are used to validate the numerical predictions. The sidewall panel is constructed from a flexible honeycomb core sandwiched between carbon fiber reinforced composite laminate face sheets. This type of construction is being used in the development of an all-composite aircraft fuselage. In contrast to conventional rib-stiffened aircraft fuselage structures, the composite panel has nominally uniform thickness resulting in a uniform distribution of mass and stiffness. Due to differences in the mass and stiffness distribution, the noise transmission mechanisms for the composite panel are expected to be substantially different from those of a conventional rib-stiffened structure. The development of accurate vibroacoustic models will aide in the understanding of the dominant noise transmission mechanisms and enable optimization studies to be performed that will determine the most beneficial noise control treatments. Finite element and boundary element models of the sidewall panel are described. Vibroacoustic response predictions are presented for forced vibration input and the results are compared with experimental data.

  10. Experimental rotordynamic coefficient results for honeycomb seals

    NASA Technical Reports Server (NTRS)

    Elrod, David A.; Childs, Dara W.

    1988-01-01

    Test results (leakage and rotordynamic coefficients) are presented for seven honeycomb-stator smooth-rotor seals. Tests were carried out with air at rotor speeds up to 16,000 cpm and supply pressures up to 8.2 bars. Test results for the seven seals are compared, and the most stable configuration is identified based on the whirl frequency ratio. Results from tests of a smooth-rotor/smooth-stator seal, a teeth-on-stator labyrinth seal, and the most stable honeycomb seal are compared.

  11. Method and apparatus for extruding large honeycombs

    DOEpatents

    Kragle, Harry A. (Corning, NY); Lambert, David W. (Corning, NY); Lipp, G. Daniel (Painted Post, NY)

    1996-09-03

    Extrusion die apparatus and an extrusion method for extruding large-cross-section honeycomb structures from plasticized ceramic batch materials are described, the apparatus comprising a die having a support rod connected to its central portion, the support rod being anchored to support means upstream of the die. The support rod and support means act to limit die distortion during extrusion, reducing die strain and stress to levels permitting large honeycomb extrusion without die failure. Dies of optimal thickness are disclosed which reduce the maximum stresses exerted on the die during extrusion.

  12. Breath Figure Method for Construction of Honeycomb Films

    PubMed Central

    Dou, Yingying; Jin, Mingliang; Zhou, Guofu; Shui, Lingling

    2015-01-01

    Honeycomb films with various building units, showing potential applications in biological, medical, physicochemical, photoelectric, and many other areas, could be prepared by the breath figure method. The ordered hexagonal structures formed by the breath figure process are related to the building units, solvents, substrates, temperature, humidity, air flow, and other factors. Therefore, by adjusting these factors, the honeycomb structures could be tuned properly. In this review, we summarized the development of the breath figure method of fabricating honeycomb films and the factors of adjusting honeycomb structures. The organic-inorganic hybrid was taken as the example building unit to discuss the preparation, mechanism, properties, and applications of the honeycomb films. PMID:26343734

  13. Aluminum Hydroxide

    MedlinePLUS

    Aluminum hydroxide is used for the relief of heartburn, sour stomach, and peptic ulcer pain and to ... Aluminum hydroxide comes as a capsule, a tablet, and an oral liquid and suspension. The dose and ...

  14. Honeycomb Geometry: Applied Mathematics in Nature.

    ERIC Educational Resources Information Center

    Roberts, William J.

    1984-01-01

    Study and exploration of the hexagonal shapes found in honeycombs is suggested as an interesting topic for geometry classes. Students learn that the hexagonal pattern maximizes the enclosed region and minimizes the wax needed for construction, while satisfying the bees' cell-size constraint. (MNS)

  15. PT-symmetry in honeycomb photonic lattices

    SciTech Connect

    Szameit, Alexander; Rechtsman, Mikael C.; Bahat-Treidel, Omri; Segev, Mordechai

    2011-08-15

    We apply gain and loss to honeycomb photonic lattices and show that the dispersion relation is identical to tachyons--particles with imaginary mass that travel faster than the speed of light. This is accompanied by -symmetry breaking in this structure. We further show that the -symmetry can be restored by deforming the lattice.

  16. Fiberglass honeycomb elements formed quickly and cheaply

    NASA Technical Reports Server (NTRS)

    Smith, R. H.

    1970-01-01

    Cookie cutter device initiates production of identical, double-contoured fiber glass elements used as shock absorbers. Three-bladed edges convert triangular honeycomb elements into hexagonal shapes which are then stamped to desired length by concave and convex dies. Sandpaper smoothing completes the process.

  17. Honeycomb artificial spin ice at low temperatures

    NASA Astrophysics Data System (ADS)

    Zeissler, Katharina; Chadha, Megha; Cohen, Lesley; Branford, Will

    2015-03-01

    Artificial spin ice is a macroscopic playground for magnetically frustrated systems. It consists of a geometrically ordered but magnetically frustrated arrangement of ferromagnetic macros spins, e.g. an arrangement of single domain ferromagnetic nanowires on a honeycomb lattice. Permalloy and cobalt which have critical temperature scales far above 290 K, are commonly used in the construction of such systems. Previous measurements have shown unusual features in the magnetotransport signature of cobalt honeycomb artificial spin ice at temperatures below 50 K which are due to changes in the artificial spin ice's magnetic reversal. In that case, the artificial spin ice bars were 1 micron long, 100 nm wide and 20 nm thick. Here we explore the low temperature magnetic behavior of honeycomb artificial spin ice structures with a variety of bar dimensions, indirectly via electrical transport, as well as, directly using low temperature magnetic imaging techniques. We discuss the extent to which this change in the magnetic reversal at low temperatures is generic to the honeycomb artificial spin ice geometry and whether the bar dimensions have an influence on its onset temperature. The EPSRC (Grant No. EP/G004765/1; Grant No. EP/L504786/1) and the Leverhulme Trust (Grant No. RPG 2012-692) funded this scientific work.

  18. Titanium honeycomb acoustic lining structural and thermal test report. [for acoustic tailpipe for JT8D engine

    NASA Technical Reports Server (NTRS)

    Joynes, D.; Balut, J. P.

    1974-01-01

    The results are presented of static, fatigue and thermal testing of titanium honeycomb acoustic panels representing the acoustic tailpipe for the Pratt and Whitney Aircraft JT8D Refan engine which is being studied for use on the Boeing 727-200 airplane. Test specimens represented the engine and tailpipe flange joints, the rail to which the thrust reverser is attached and shear specimens of the tailpipe honeycomb. Specimens were made in four different batches with variations in configuration, materials and processes in each. Static strength of all test specimens exceeded the design ultimate load requirements. Fatigue test results confirmed that aluminum brazed titanium, as used in the Refan tailpipe design, meets the fatigue durability objectives. Quality of welding was found to be critical to life, with substandard welding failing prematurely, whereas welding within the process specification exceeded the panel skin life. Initial fatigue testing used short grip length bolts which failed prematurely. These were replaced with longer bolts and subsequent testing demonstrated the required life. Thermal tests indicate that perforated skin acoustic honeycomb has approximately twice the heat transfer of solid skin honeycomb.

  19. Radiated Sound Power from a Curved Honeycomb Panel

    NASA Technical Reports Server (NTRS)

    Robinson, Jay H.; Buehrle, Ralph D.; Klos, Jacob; Grosveld, Ferdinand W.

    2003-01-01

    The validation of finite element and boundary element model for the vibro-acoustic response of a curved honeycomb core composite aircraft panel is completed. The finite element and boundary element models were previously validated separately. This validation process was hampered significantly by the method in which the panel was installed in the test facility. The fixture used was made primarily of fiberboard and the panel was held in a groove in the fiberboard by a compression fitting made of plastic tubing. The validated model is intended to be used to evaluate noise reduction concepts from both an experimental and analytic basis simultaneously. An initial parametric study of the influence of core thickness on the radiated sound power from this panel, using this numerical model was subsequently conducted. This study was significantly influenced by the presence of strong boundary condition effects but indicated that the radiated sound power from this panel was insensitive to core thickness primarily due to the offsetting effects of added mass and added stiffness in the frequency range investigated.

  20. Engineering polar discontinuities in honeycomb lattices.

    PubMed

    Gibertini, Marco; Pizzi, Giovanni; Marzari, Nicola

    2014-01-01

    Unprecedented and fascinating phenomena have been recently observed at oxide interfaces between centrosymmetric cubic materials, where polar discontinuities can give rise to polarization charges and electric fields that drive a metal-insulator transition and the appearance of a two-dimensional electron gas. Lower-dimensional analogues are possible, and honeycomb lattices offer a fertile playground, thanks to their versatility and the extensive ongoing experimental efforts in graphene and related materials. Here we suggest different realistic pathways to engineer polar discontinuities in honeycomb lattices and support these suggestions with extensive first-principles calculations. Several approaches are discussed, based on (i) nanoribbons, where a polar discontinuity against the vacuum emerges, and (ii) functionalizations, where covalent ligands are used to engineer polar discontinuities by selective or total functionalization of the parent systems. All the cases considered have the potential to deliver innovative applications in ultra-thin and flexible solar-energy devices and in micro- and nano-electronics. PMID:25300521

  1. Engineering polar discontinuities in honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Gibertini, Marco; Pizzi, Giovanni; Marzari, Nicola

    2014-10-01

    Unprecedented and fascinating phenomena have been recently observed at oxide interfaces between centrosymmetric cubic materials, where polar discontinuities can give rise to polarization charges and electric fields that drive a metal-insulator transition and the appearance of a two-dimensional electron gas. Lower-dimensional analogues are possible, and honeycomb lattices offer a fertile playground, thanks to their versatility and the extensive ongoing experimental efforts in graphene and related materials. Here we suggest different realistic pathways to engineer polar discontinuities in honeycomb lattices and support these suggestions with extensive first-principles calculations. Several approaches are discussed, based on (i) nanoribbons, where a polar discontinuity against the vacuum emerges, and (ii) functionalizations, where covalent ligands are used to engineer polar discontinuities by selective or total functionalization of the parent systems. All the cases considered have the potential to deliver innovative applications in ultra-thin and flexible solar-energy devices and in micro- and nano-electronics.

  2. Thermographic Inspection of Metallic Honeycomb Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Taylor, John O.; Dupont, H. M.

    1998-01-01

    The X-33/VentureStar has a Thermal Protection System (TPS) consisting mainly of brazed metallic honeycomb sandwich structures. Inspection of these structures is changing as a result of the extremely thin (less than 200 microns) skins, the small critical defect size (less than 2 mm long by 100 microns wide) and the large number (more than 1000) of parts to be inspected. Pulsed Infrared Thermography has been determined to be the most appropriate inspection method for manufacturing inspection based on performance comparison with other methods, cost, schedule and other factors. The results of the assessment of the different methods will be summarized and data on the performance of the final production inspection system will be given. Finite difference thermal methods have been used to model the whole inspection process. Details of correlation between the models and experimental data will be given and data on the use of pulsed infrared thermography on other metallic honeycomb sandwich structures will be given.

  3. Thermal phase transitions in a honeycomb lattice gas with three-body interactions.

    PubMed

    Lohöfer, Maximilian; Bonnes, Lars; Wessel, Stefan

    2013-11-01

    We study the thermal phase transitions in a classical (hard-core) lattice gas model with nearest-neighbor three-body interactions on the honeycomb lattice, based on parallel tempering Monte Carlo simulations. This system realizes incompressible low-temperature phases at fractional fillings of 9/16, 5/8, and 3/4 that were identified in a previous study of a related quantum model. In particular, both the 9/16 and the 5/8 phase exhibit an extensive ground-state degeneracy reflecting the frustrated nature of the three-body interactions on the honeycomb lattice. The thermal melting of the 9/16 phase is found to be a first-order, discontinuous phase transition. On the other hand, from the thermodynamic behavior we obtain indications for a four-states Potts-model thermal transition out of the 5/8 phase. We find that this thermal Potts-model transition relates to the selection of one out of four extensive sectors within the low-energy manifold of the 5/8 phase, which we obtain via an exact mapping of the ground-state manifold to a hard-core dimer model on an embedded honeycomb superlattice. PMID:24329242

  4. 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.

  5. Mechanics and applications of pressure adaptive honeycomb

    NASA Astrophysics Data System (ADS)

    Vos, Roelof

    A novel adaptive aerostructure is presented that relies on certified aerospace materials and can therefore be applied in conventional passenger aircraft. This structure consists of a honeycomb material which' cells extend over a significant length perpendicular to the plane of the cells. Each of the cells contains an inelastic pouch (or bladder) that forms a circular tube when the cell forms a perfect hexagon. By changing the cell differential pressure (CDP) the stiffness of the honeycomb can be altered. Using an external force or the elastic force within the honeycomb material, the honeycomb can be deformed such that the cells deviate from their perfect-hexagonal shape. It can be shown that by increasing the CDP, the structure eventually returns to a perfect hexagon. By doing so, a fully embedded pneumatic actuator is created that can perform work and substitute conventional low-bandwidth flight control actuators. It is shown that two approaches can be taken to regulate the stiffness of this embedded actuator: (1) The first approach relies on the pouches having a fixed amount of air in them and stiffness is altered by a change in ambient pressure. Coupled to the ambient pressure-altitude cycle that aircraft encounter during each flight, this approach yields a true adaptive aerostructure that operates independently of pilot input and is controlled solely by the altitude the aircraft is flying at. (2) The second approach relies on a controlled constant CDP. This CDP could be supplied from one of the compressor stages of the engine as a form of bleed air. Because of the air-tight pouches there would essentially be no mass flow, meaning engine efficiency would not be significantly affected due to this application. By means of a valve system the pilot could have direct control over the pressure and, consequently, the stiffness of the structure. This allows for much higher CDPs (on the order of 1MPa) than could physically be achieved by relying on the ambient pressure decrease with altitude. This option does require more infrastructure like tubing, valves, and supporting electronics from the cockpit. Applications of pressure adaptive honeycomb are tailored primarily towards low-bandwidth applications like secondary flight control. The most profound application is the morphing of an entire wing section, from leading to trailing edge, due to the adaptive honeycomb. On a smaller scale, other examples include a solid state pressure adaptive flap, a pressure adaptive droop nose, a pressure adaptive Gurney flap and a pressure adaptive engine inlet. Each of these applications is based on the same principle of stiffness alteration with pressure and can be used with either actuation option (constant mass or constant pressure). A model that relates the volumetric change of the honeycomb cells to the external blocked stress was shown to correlate well to experiments that were carried out on several test articles. Based on this model it was estimated that pressure adaptive honeycomb has a maximum mass-specific energy density of 12.4J/g, for the case of an externally applied CDP of 0.9MPa (can be supplied from a high-pressure compressor stage of a gas turbine). In addition, it was shown that a maximum strain of 76% can be achieved and that the maximum blocked stress amounts to 0.82MPa. In the case of a 40kPa drop in atmospheric pressure and constant mass of air in the pouches, the maximum mass specific energy amounts to 1.1J/g and a maximum blocked force of 70kPa can be attained. Pressure adaptive honeycomb was embedded into a 25%c adaptive flap on a NACA2412 wing section with a chord of 1.08m. Wind tunnel tests at Reynolds number of 1 million demonstrated a shift in the cl -- alpha curve upwards by an average of 0.3, thereby increasing the maximum lift coefficient from 1.27 to 1.52. This successfully demonstrated the application of pressure adaptive honeycomb embedded in a morphing aircraft structure.

  6. Forced convection in metallic honeycomb structures , J. Tian a

    E-print Network

    Wadley, Haydn

    Forced convection in metallic honeycomb structures T. Wen a , J. Tian a , T.J. Lu a,b,*, D face-sheet heated by con- stant heat flux and cooled by forced air convection, have been investigated reserved. Keywords: Forced convection; Metallic honeycomb structures; Experiment; Numerical calculation 1

  7. Clean Electrical-Discharge Machining Of Delicate Honeycomb

    NASA Technical Reports Server (NTRS)

    Johnson, Clarence S.

    1993-01-01

    Precise recesses in fragile metal honeycomb blocks formed in special electrical-discharge machining process. Special tooling used, and recesses bored with workpiece in nonstandard alignment. Cutting electrode advances into workpiece along x axis to form pocket of rectangular cross section. Deionized water flows from fitting, along honeycomb tubes of workpiece, to electrode/workpiece interface.

  8. Interacting growth walk on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Narasimhan, S. L.; Sridhar, V.; Murthy, K. P. N.

    2003-03-01

    The interacting growth walk (IGW) is a kinetic algorithm proposed recently for generating long, lattice polymer configurations. The growth process in IGW is tuned by a parameter called the growth temperature TG=1/( kB?G). In this paper we consider IGW on a honeycomb lattice. We take the non-bonded nearest neighbour contact energy as ?=-1. We show that at ?G=0, IGW algorithm generates a canonical ensemble of interacting self-avoiding walks at ?= ??(? G=0)= ln(2) . However for ?G>0, IGW generates an ensemble of polymer configurations most of which are in equilibrium at ?= ??(? G) . The remaining ones are frozen in ‘non-equilibrium’ configurations.

  9. Aluminum Analysis.

    ERIC Educational Resources Information Center

    Sumrall, William J.

    1998-01-01

    Presents three problems based on the price of aluminum designed to encourage students to be cooperative and to use an investigative approach to learning. Students collect and synthesize information, analyze results, and draw conclusions. (AIM)

  10. Study on mechanical properties of steel honeycomb panel three-point bending specimen under in-plane and out-plane transverse dynamic impact load

    NASA Astrophysics Data System (ADS)

    Zou, Guangping; Chang, Zhongliang; Xia, Xingyou; Zhang, Xueyi

    2010-03-01

    The metal honeycomb material has high strength and high stiffness, as a high-performance sandwich panel, it is an ideal lightweight structural material, and widely used in aviation, aerospace, shipbuilding and other fields. In this paper, the improved SHPB instrument is used for testing the in-plane and out-plane mechanical properties of the steel honeycomb panel three-point bending specimen, and also compare the results with the static in-plane and out-plane three-point bending experiments results which is tested by the INSTRON 4505 electronic universal testing machine, and then study the mechanical properties of the steel honeycomb panel three-point bending specimen under transverse dynamic impact load. From the results it can be see that, for the out-plane three point bending experiment, L direction mechanical properties is better than the W direction, and the honeycomb core play an important role during the specimen deformation, while for the in-plane three point bending experiment, the honeycomb core mechanical role is not distinctness.

  11. Study on mechanical properties of steel honeycomb panel three-point bending specimen under in-plane and out-plane transverse dynamic impact load

    NASA Astrophysics Data System (ADS)

    Zou, Guangping; Chang, Zhongliang; Xia, Xingyou; Zhang, Xueyi

    2009-12-01

    The metal honeycomb material has high strength and high stiffness, as a high-performance sandwich panel, it is an ideal lightweight structural material, and widely used in aviation, aerospace, shipbuilding and other fields. In this paper, the improved SHPB instrument is used for testing the in-plane and out-plane mechanical properties of the steel honeycomb panel three-point bending specimen, and also compare the results with the static in-plane and out-plane three-point bending experiments results which is tested by the INSTRON 4505 electronic universal testing machine, and then study the mechanical properties of the steel honeycomb panel three-point bending specimen under transverse dynamic impact load. From the results it can be see that, for the out-plane three point bending experiment, L direction mechanical properties is better than the W direction, and the honeycomb core play an important role during the specimen deformation, while for the in-plane three point bending experiment, the honeycomb core mechanical role is not distinctness.

  12. Cryogenic performance of slotted brazed Rene 41 honeycomb panels

    NASA Technical Reports Server (NTRS)

    Hepler, A. K.; Swegle, A. R.

    1982-01-01

    Two brazed Rene 41 honeycomb panels that would incorporate a frame element were designed, fabricated and tested. The panels were representative of the lower surface of an advanced space transportation vehicle. The first panel was a two span panel supported by a center frame and on edges parallel to it. The second panel was a two span panel supported by a center frame and on edges parallel to it. The second panel was a three span panel supported on two frames and on edges parallel to the frames. Each panel had its outer skin slotted to reduce the thermal stresses of the panel skins. The first panel was tested under simulated boost conditions that included liquid hydrogen exposure of the frame and inner skin and radiant heat to 478K on the outer skins. The first panel was tested to investigate the effect of thermal stresses in skins and core caused by the panel being restrained by a cold integral frame and to observe the effects of frost formation and possible liquid air development in and around outer skin slots.

  13. 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.

  14. Test results for electron beam charging of flexible insulators and composites. [solar array substrates, honeycomb panels, and thin dielectric films

    NASA Technical Reports Server (NTRS)

    Staskus, J. V.; Berkopec, F. D.

    1979-01-01

    Flexible solar-array substrates, graphite-fiber/epoxy - aluminum honeycomb panels, and thin dielectric films were exposed to monoenergetic electron beams ranging in energy from 2 to 20 keV in the Lewis Research Center's geomagnetic-substorm-environment simulation facility to determine surface potentials, dc currents, and surface discharges. The four solar-array substrate samples consisted of Kapton sheet reinforced with fabrics of woven glass or carbon fibers. They represented different construction techniques that might be used to reduce the charge accumulation on the array back surface. Five honeycomb-panel samples were tested, two of which were representative of Voyager antenna materials and had either conductive or nonconductive painted surfaces. A third sample was of Navstar solar-array substrate material. The other two samples were of materials proposed for use on Intelsat V. All the honeycomb-panel samples had graphite-fiber/epoxy composite face sheets. The thin dielectric films were 2.54-micrometer-thick Mylar and 7.62-micrometer-thick Kapton.

  15. Active inflatable auxetic honeycomb structural concept for morphing wingtips

    NASA Astrophysics Data System (ADS)

    Sun, Jian; Gao, Hongliang; Scarpa, Fabrizio; Lira, Cristian; Liu, Yanju; Leng, Jinsong

    2014-12-01

    This paper describes a new concept of an active honeycomb structure for morphing wingtip applications based on tubular inflatable systems and an auxetic cellular structure. A work-energy model to predict the output honeycomb displacement versus input pressure is developed together with a finite element formulation, and the results are compared with the data obtained from a small-scale example of an active honeycomb. An analysis of the hysteresis associated with multiple cyclic loading is also provided, and design considerations for a larger-scale wingtip demonstrator are made.

  16. Damping capacity in shape memory alloy honeycomb structures

    NASA Astrophysics Data System (ADS)

    Boucher, M.-A.; Smith, C. W.; Scarpa, F.; Miller, W.; Hassan, M. R.

    2010-04-01

    SMA honeycombs have been recently developed by several Authors [1, 2] as innovative cellular structures with selfhealing capability following mechanical indentation, unusual deformation (negative Poisson's ratio [3]), and possible enhanced damping capacity due to the natural vibration dissipation characteristics of SMAs under pseudoelastic and superelastic regime. In this work we describe the nonlinear damping effects of novel shape memory alloy honeycomb assemblies subjected to combine mechanical sinusoidal and thermal loading. The SMA honeycomb structures made with Ni48Ti46Cu6 are designed with single and two-phase polymeric components (epoxy), to enhance the damping characteristics of the base SMA for broadband frequency vibration.

  17. Crystallography of rare galactic honeycomb structure near supernova 1987a

    NASA Technical Reports Server (NTRS)

    Noever, David A.

    1994-01-01

    Near supernova 1987a, the rare honeycomb structure of 20-30 galactic bubbles measures 30 x 90 light years. Its remarkable regularity in bubble size suggests a single-event origin which may correlate with the nearby supernova. To test the honeycomb's regularity in shape and size, the formalism of statistical crystallography is developed here for bubble sideness. The standard size-shape relations (Lewis's law, Desch's law, and Aboav-Weaire's law) govern area, perimeter and nearest neighbor shapes. Taken together, they predict a highly non-equilibrium structure for the galactic honeycomb which evolves as a bimodal shape distribution without dominant bubble perimeter energy.

  18. Honeycomb nozzle unit for gasdynamic lasers

    NASA Astrophysics Data System (ADS)

    Achasov, O. V.; Boreisho, A. S.; Bykov, A. M.; Lebedev, V. F.; Morozov, A. V.; Labuda, S. A.; Ragozin, D. S.; Soloukhin, R. I.; Fomin, N. A.

    1984-09-01

    Experimental results on the gain characteristics of CO2 gasdynamic lasers with honeycomb nozzle units are reported. The experimental nozzle unit contained 48 axisymmetric profiled nozzles of critical section diameter of 1.1 mm and expansion ratio of about 36; the radiating gas component (a 1:3 mixture of CO2 and He) was injected normal to the nozzle surface through two openings of 5-mm diameter. Weak-signal gain was studied as a function of the pressure of the radiating mixture; the peak values were observed at 1.3 MPa and were equal to 1.7, 1.8, 1.6, and 1.4/m at 25, 60, 160, and 260 mm beyond the cutoff, respectively.

  19. Nuclear design analysis of square-lattice honeycomb space nuclear rocket engine

    SciTech Connect

    Widargo, Reza; Anghaie, Samim

    1999-01-22

    The square-lattice honeycomb reactor is designed based on a cylindrical core that is determined to have critical diameter and length of 0.50 m and 0.50 c, respectively. A 0.10-cm thick radial graphite reflector, in addition to a 0.20-m thick axial graphite reflector are used to reduce neutron leakage from the reactor. The core is fueled with solid solution of 93% enriched (U, Zr, Nb)C, which is one of several ternary uranium carbides that are considered for this concept. The fuel is to be fabricated as 2 mm grooved (U, Zr, Nb)C wafers. The fuel wafers are used to form square-lattice honeycomb fuel assemblies, 0.10 m in length with 30% cross-sectional flow area. Five fuel assemblies are stacked up axially to form the reactor core. Based on the 30% void fraction, the width of the square flow channel is about 1.3 mm. The hydrogen propellant is passed through these flow channels and removes the heat from the reactor core. To perform nuclear design analysis, a series of neutron transport and diffusion codes are used. The preliminary results are obtained using a simple four-group cross-section model. To optimize the nuclear design, the fuel densities are varied for each assembly. Tantalum, hafnium and tungsten are considered and used as a replacement for niobium in fuel material to provide water submersion sub-criticality for the reactor. Axial and radial neutron flux and power density distributions are calculated for the core. Results of the neutronic analysis indicate that the core has a relatively fast spectrum. From the results of the thermal hydraulic analyses, eight axial temperature zones are chosen for the calculation of group average cross-sections. An iterative process is conducted to couple the neutronic calculations with the thermal hydraulics calculations. Results of the nuclear design analysis indicate that a compact core can be designed based on ternary uranium carbide square-lattice honeycomb fuel. This design provides a relatively high thrust to weight ratio.

  20. Thermal hydraulic design analysis of ternary carbide fueled square-lattice honeycomb nuclear rocket engine

    SciTech Connect

    Furman, Eric M.; Anghaie, Samim

    1999-01-22

    A computational analysis is conducted to determine the optimum thermal-hydraulic design parameters for a square-lattice honeycomb nuclear rocket engine core that will incorporate ternary carbide based uranium fuels. Recent studies at the Innovative Nuclear Space Power and Propulsion Institute (INSPI) have demonstrated the feasibility of processing solid solution, ternary carbide fuels such as (U, Zr, Nb)C, (U, Zr, Ta)C, (U, Zr, Hf)C and (U, Zr, W)C. The square-lattice honeycomb design provides high strength and is amenable to the processing complexities of these ultrahigh temperature fuels. A parametric analysis is conducted to examine how core geometry, fuel thickness and the propellant flow area effect the thermal performance of the nuclear rocket engine. The principal variables include core size (length and diameter) and fuel element dimensions. The optimum core configuration requires a balance between high specific impulse and thrust level performance, and maintaining the temperature and strength limits of the fuel. A nuclear rocket engine simulation code is developed and used to examine the system performance as well as the performance of the main reactor core components. The system simulation code was originally developed for analysis of NERVA-Derivative and Pratt and Whitney XNR-2000 nuclear thermal rockets. The code is modified and adopted to the square-lattice geometry of the new fuel design. Thrust levels ranging from 44,500 to 222,400 N (10,000 to 50,000 lbf) are considered. The average hydrogen exit temperature is kept at 2800 K, which is well below the melting point of these fuels. For a nozzle area ratio of 300 and a thrust chamber pressure of 4.8 Mpa (700 psi), the specific impulse is 930 s. Hydrogen temperature and pressure distributions in the core and the fuel maximum temperatures are calculated.

  1. Assessment of Bulk Absorber Properties for Multi-Layer Perforates in Porous Honeycomb Liners

    NASA Technical Reports Server (NTRS)

    Jones, Michael G.; Parrott, Tony L.

    2006-01-01

    CONTINUING progress in materials technology provides potential for improved acoustic liners for attenuating broadband fan noise emissions from aircraft engine nacelles. Conventional liners (local-reacting perforate-over-honeycomb structures) provide significant narrow-band attenuation, but limited attenuation over wide bandwidths. Two approaches for increasing attenuation bandwidth are to (1) replace the honeycomb structure with bulk material, or (2) cascade multiple layers of perforate/honeycomb structures. Usage of the first approach is limited because of mechanical and maintenance reasons, while multi-layer liners are limited to about three layers because of their additional mechanical complexity, depth and weight. The current research concerns a novel approach reported by the University of Cincinnati, in which a single-layer conventional liner is converted into an extended-reaction, broadband absorber by making the honeycomb core structure porous. This modified single-layer liner requires no increase in depth and weight, and minimal increase in mechanical complexity. Langley has initiated research to identify potential benefits of liner structures with porous cell walls. This research has two complementary goals: (1) develop and validate experimental techniques for treating multi-layer perforates (representative of the internal cells of a liner with porous cell walls) as 1-D bulk materials, and (2) develop analytical approaches to validate this bulk material assumption. If successful, the resultant model can then be used to design optimized porous honeycomb liners. The feasibility of treating an N-layer perforate system (N porous plates separated by uniform air gaps) as a one-dimensional bulk absorber is assessed using the Two-Thickness Method (TTM), which is commonly used to educe bulk material intrinsic acoustic parameters. Tests are conducted with discrete tone and random noise sources, over an SPL range sufficient to determine the nonlinearity of the test specimens, for test specimens consisting of 5, 10 and 15% porous plates. Measured impedances for two liner thicknesses (e.g., 12 and 24 layers) are used as input to the TTM to determine the characteristic impedance and propagation constant that characterize these liners as bulk absorbers. These parameters are then used to calculate the predicted impedance of liners with different thicknesses (e.g., 36 layers), and a comparison of predicted and measured impedances for these other thicknesses is used to determine the efficacy of this approach. Finally, an independent method is used to educe the propagation constant for a single representative sample, and excellent comparison between the results for this method and those for the TTM provides increased confidence in the results achieved with the TTM. In general, the results demonstrate these multi-layer perforates can be acceptably treated as bulk absorbers.

  2. Elastic constants for superplastically formed/diffusion-bonded corrugated sandwich core

    NASA Technical Reports Server (NTRS)

    Ko, W. L.

    1980-01-01

    Formulas and associated graphs for evaluating the effective elastic constants for a superplastically formed/diffusion bonded (SPF/DB) corrugated sandwich core, are presented. A comparison of structural stiffnesses of the sandwich core and a honeycomb core under conditions of equal sandwich core density was made. The stiffness in the thickness direction of the optimum SPF/DB corrugated core (that is, triangular truss core) is lower than that of the honeycomb core, and that the former has higher transverse shear stiffness than the latter.

  3. Dynamics of artificial spin ice: a continuous honeycomb network

    E-print Network

    Shen, Yichen

    We model the dynamics of magnetization in an artificial analogue of spin ice specializing to the case of a honeycomb network of connected magnetic nanowires. The inherently dissipative dynamics is mediated by the emission ...

  4. Low voltage reversible electrowetting exploiting lubricated polymer honeycomb substrates

    NASA Astrophysics Data System (ADS)

    Bormashenko, Edward; Pogreb, Roman; Bormashenko, Yelena; Grynyov, Roman; Gendelman, Oleg

    2014-04-01

    Low-voltage electrowetting-on-dielectric scheme realized with lubricated honeycomb polymer surfaces is reported. Polycarbonate honeycomb reliefs manufactured with the breath-figures self-assembly were impregnated with silicone and castor oils. The onset of the reversible electrowetting for silicone oil impregnated substrates occurred at 35 V, whereas for castor oil impregnated ones it took place at 80 V. The semi-quantitative analysis of electrowetting of impregnated surfaces is proposed.

  5. Low Voltage Reversible Electrowetting Exploiting Lubricated Polymer Honeycomb Substrates

    E-print Network

    Edward Bormashenko; Roman Pogreb; Yelena Bormashenko; Roman Grynyov; Oleg Gendelman

    2014-06-16

    Low-voltage electrowetting-on-dielectric scheme realized with lubricated honeycomb polymer surfaces is reported. Polycarbonate honeycomb reliefs manufactured with the breath-figures self-assembly were impregnated with silicone and castor oils. The onset of the reversible electrowetting for silicone oil impregnated substrates occurred at 35 V, whereas for castor oil impregnated ones it took place at 80 V. The semi-quantitative analysis of electrowetting of impregnated surfaces is proposed.

  6. Aluminum phosphide

    Integrated Risk Information System (IRIS)

    Aluminum phosphide ; CASRN 20859 - 73 - 8 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinoge

  7. Aluminum Pannier

    USGS Multimedia Gallery

    This aluminum pannier was made for the storage of meat, vegetables and other food products. The pannier could be buried in the ground or placed in water in order to keep the contents cool. It was designed by Dr. J. D. Love and made for him in 1945. For transportation, this pannier, along with two re...

  8. New concept in brazing metallic honeycomb panels

    NASA Technical Reports Server (NTRS)

    Carter, P. D.; Layton, R. E.; Stratton, F. W.

    1973-01-01

    Aluminum oxide coating provides surface which will not be wetted by brazing alloy and which stops metallic diffusion welding of tooling materials to part being produced. This method eliminates loss of tooling materials and parts from braze wetting and allows fall-apart disassembly of tooling after brazing.

  9. Chemical interactions of aluminum-citrate solutions with formation minerals

    SciTech Connect

    Walsh, M.P.; Rouse, B.A.; Pope, G.A.; Lake, L.W.; Senol, N.N.

    1983-01-01

    To test the effectiveness of complexing agents for in-depth cross-linking and mobility control in polymer and waterfloods, the transport of aluminum citrate solutions in sandstone and limestone cores was investigated. The study was prompted by experimental observations indicating that cross-linking attempts cause plugging of the inlet end of core sections unless special precautions were observed. The plugging was caused by poor transport of the aluminum citrate solutions, which, in turn, was caused by precipitation of aluminum hydroxide in limestone cores, and of both aluminum and ferric hydroxide in sandstone cores. The formation of these precipitates and the poor transport of the aluminum citrate solution were confirmed experimentally and modeled quantitatively by a geochemical flow simulator. The flow simulator was used then to design injected solutions that would avoid precipitation, generally by raising the injected pH and by using a larger citrate to aluminum ratio. 28 references.

  10. Development of Rene' 41 honeycomb structure as an integral cryogenic tankage/fuselage concept for future space transportation systems

    NASA Technical Reports Server (NTRS)

    Shideler, J. J.; Swegle, A. R.; Fields, R. A.

    1982-01-01

    The status of the structural development of an integral cryogenic-tankage/hot-fuselage concept for future space transportation systems (STS) is discussed. The concept consists of a honeycomb sandwich structure which serves the combined functions of containment of cryogenic fuel, support of vehicle loads, and thermal protection from an entry heating environment. The inner face sheet is exposed to a cryogenic (LH2) temperature of -423 F during boost; and the outer face sheet, which is slotted to reduce thermal stress, is exposed to a maximum temperature of 1400 F during a high altitude, gliding entry. A fabrication process for a Rene' 41 honeycomb sandwich panel with a core density less than 1 percent was developed which is consistent with desirable heat treatment processes for high strength.

  11. Edge states in polariton honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Mili?evi?, M.; Ozawa, T.; Andreakou, P.; Carusotto, I.; Jacqmin, T.; Galopin, E.; Lemaître, A.; Le Gratiet, L.; Sagnes, I.; Bloch, J.; Amo, A.

    2015-09-01

    The experimental study of edge states in atomically thin layered materials remains a challenge due to the difficult control of the geometry of the sample terminations, the stability of dangling bonds, and the need to measure local properties. In the case of graphene, localized edge modes have been predicted in zigzag and bearded edges, characterized by flat dispersions connecting the Dirac points. Polaritons in semiconductor microcavities have recently emerged as an extraordinary photonic platform to emulate 1D and 2D Hamiltonians, allowing the direct visualization of the wavefunctions in both real- and momentum-space as well as of the energy dispersion of eigenstates via photoluminescence experiments. Here we report on the observation of edge states in a honeycomb lattice of coupled micropillars. The lowest two bands of this structure arise from the coupling of the lowest energy modes of the micropillars, and emulate the ? and ?* bands of graphene. We show the momentum-space dispersion of the edge states associated with the zigzag and bearded edges, holding unidimensional quasi-flat bands. Additionally, we evaluate polarization effects characteristic of polaritons on the properties of these states.

  12. Edge states in polariton honeycomb lattices

    E-print Network

    Milicevic, M; Andreakou, P; Carusotto, I; Jacqmin, T; Galopin, E; Lemaître, A; Gratiet, L Le; Sagnes, I; Bloch, J; Amo, A

    2015-01-01

    The experimental study of edge states in atomically-thin layered materials remains a challenge due to the difficult control of the geometry of the sample terminations, the stability of dangling bonds and the need to measure local properties. In the case of graphene, localised edge modes have been predicted in zig-zag and bearded edges, characterised by flat dispersions connecting the Dirac points. Polaritons in semiconductor microcavities have recently emerged as an extraordinary photonic platform to emulate 1D and 2D Hamiltonians, allowing the direct visualization of the wavefunctions in both real- and momentum-space as well as of the energy dispersion of eigenstates via photoluminescence experiments. Here we report on the observation of edge states in a honeycomb lattice of coupled micropillars. The lowest two bands of this structure arise from the coupling of the lowest energy modes of the micropillars, and emulate the {\\pi} and {\\pi}* bands of graphene. We show the momentum space dispersion of the edge st...

  13. Analysis of propagation characteristics of flexural wave in honeycomb sandwich panel and design of loudspeaker for radiating inclined sound

    NASA Astrophysics Data System (ADS)

    Fujii, Ayaka; Wakatsuki, Naoto; Mizutani, Koichi

    2015-07-01

    A loudspeaker for an auditory guiding system is proposed. This loudspeaker utilizes inclined sound transformed from a flexural wave in a honeycomb sandwich panel. We focused on the fact that the inclined sound propagates extensively with uniform level and direction. Furthermore, sound can be generated without group delay dispersion because the phase velocity of the flexural wave in the sandwich panel becomes constant with increasing frequency. These characteristics can be useful for an auditory guiding system in public spaces since voice-guiding navigation indicates the right direction regardless of position on a pathway. To design the proposed loudspeaker, the behavior of the sandwich panel is predicted using a theoretical equation in which the honeycomb core is assumed as an orthotropic continuum. We calculated the phase velocity dispersion of the flexural wave in the sandwich panel and compared the results obtained using the equation with those of a simulation based on the finite element method and an experiment in order to confirm the applicability of the theoretical equation. It was confirmed that the phase velocities obtained using the theoretical equation and by the simulation were in good agreement with that obtained experimentally. The obtained results suggest that the behavior of the sandwich panel can be predicted using the parameters of the panel. In addition, we designed an optimized honeycomb sandwich panel for radiating inclined sound by calculating the phase velocity characteristics of various panels that have different parameters of core height and cell size using the theoretical equation. Sound radiation from the optimized panel was simulated and compared with that of a homogeneous plate. It was clear that the variance of the radiation angle with varying frequency of the optimized panel was smaller than that of the homogeneous plate. This characteristic of sound radiation with a uniform angle is useful for indicating the destination direction. On the basis of this fact, we established a design method of the flat-panel loudspeaker for generating inclined sound using a honeycomb sandwich panel.

  14. Effects of service environments on aluminum-brazed titanium (ABTi)

    NASA Technical Reports Server (NTRS)

    Cotton, W. L.

    1978-01-01

    Aluminum brazed titanium (ABTi) structures were evaluated during prolonged exposure to extreme environments: elevated temperature exposure to airline service fluids, hydraulic fluid, and seawater, followed by laboratory corrosion tests. Solid-face and perforated face honeycomb sandwich panel specimens, stressed panel assemblies, and faying surface brazed joints were tested. The corrosion resistance of ABTi is satisfactory for commercial airline service. Unprotected ABTi proved inherently resistant to attack by all of the extreme service aircraft environments except: seawater at 700 K (800 F) and above, dripping phosphate ester hydraulic fluid at 505 K (450 F), and a marine environment at ambient temperature. The natural oxides and deposits present on titanium surfaces in airline service provide protection against hot salt corrosion pitting. Coatings are required to protect titanium dripping phosphate ester fluid at elevated temperatures and to protect exposed acoustic honeycomb parts against corrosion in a marine environment.

  15. Optimal Design of Honeycomb Material Used to Mitigate Head Impact

    PubMed Central

    Caccese, Vincent; Ferguson, James R.; Edgecomb, Michael

    2013-01-01

    This paper presents a study of the impact resistance of honeycomb structure with the purpose to mitigate impact forces. The objective is to aid in the choice of optimal parameters to minimize the thickness of the honeycomb structure while providing adequate protection to prevent injury due to head impact. Studies are presented using explicit finite element analysis representing the case of an unprotected drop of a rigid impactor onto a simulated floor consisting of vinyl composition tile and concrete. Analysis of honeycomb material to reduce resulting accelerations is also presented where parameters such as honeycomb material modulus, wall thickness, cell geometry and structure depth are compared to the unprotected case. A simplified analysis technique using a genetic algorithm is presented to demonstrate the use of this method to select a minimum honeycomb depth to achieve a desired acceleration level at a given level of input energy. It is important to select a minimum material depth in that smaller dimensions lead toward more aesthetic design that increase the likelihood of that the device is used. PMID:23976812

  16. Brazing dissimilar aluminum alloys

    NASA Technical Reports Server (NTRS)

    Dalalian, H.

    1979-01-01

    Dip-brazing process joins aluminum castings to aluminum sheet made from different aluminum alloy. Process includes careful cleaning, surface preparation, and temperature control. It causes minimum distortion of parts.

  17. Steps Toward 8M Honeycomb Mirror Blanks: III. 1.8m Honeycomb Sandwich Blanks Cast From Borosilicate Glass

    NASA Astrophysics Data System (ADS)

    Angel, J. R. P.; Hill, J. M.

    1983-11-01

    As part of a program leading to the production of 8m honeycomb mirrors, we have recently made two 1.8m blanks. These have honeycomb sandwich form, with hexagonal honeycomb ribs sandwiched between front and back plates. Each is cast in one piece from borosilicate glass, using techniques that can be extended to larger sizes. Pieces of the glass are melted together in a circular container made of hard ceramic tiles, held together against hydrostatic pressure by bands of nickel alloy. Voids in the glass to give the honeycomb structure are formed by hexagonal blocks of ceramic fiber, held down against flotation with silicon carbide bolts. Liquid glass runs over the blocks to form the face sheet, and under the blocks, which are spaced above the base tiles, to form a back sheet with holes. After the casting has been annealed and cooled, the base tiles are unbolted and the ceramic fiber blocks removed from the glass honeycomb by water blasting. Both blanks are of high quality, free from cracks and voids, and with an adequately low bubble content. The second and better blank, made of Ohara's E6 glass, is now to be figured to high precision, 0.25 arcsecond images, and is to be tested for an extended period in the Multiple Mirror Telescope.

  18. Magnetic and thermodynamic properties of the harmonic honeycomb iridates

    NASA Astrophysics Data System (ADS)

    Analytis, James

    2015-03-01

    Spin and orbital quantum numbers play a key role in the physics of Mott insulators, but in most systems they are connected only indirectly--via the Pauli exclusion principle and the Coulomb interaction. Iridium-based oxides (iridates) introduce strong spin-orbit coupling directly, such that these numbers become entwined together and the Mott physics attains a strong orbital character. In the layered honeycomb iridates this is thought to generate highly spin-anisotropic magnetic interactions, coupling the spin to a given spatial direction of exchange and leading to strongly frustrated magnetism. Here we report a new iridate structure that has the same local connectivity as the layered honeycomb and exhibits striking evidence for highly spin-anisotropic exchange. The basic structural units of this material suggest that a new family of three-dimensional structures could exist, the `harmonic honeycomb' iridates, of which the present compound is the first example.

  19. Mechanical analysis of confectioning flaw of refractory alloy honeycomb sandwich structure

    NASA Astrophysics Data System (ADS)

    He, Xiaodong; Kong, Xianghao; Shi, Liping; Li, Mingwei

    2009-03-01

    Thermal protection system is one of the key technology of reusable launch vehicle (RLV). After C/C and ceramic-matrix composite used in space orbiter, one new-typed thermal protection systems (TPS)-ARMOR TPS is coming forth. ARMOR TPS is means adaptable, robust, metallic, operable, reusable TPS. The ARMOR TPS has many advantages, for example: fixing easily, longer life, good properties, short time of maintenance and service. The ARMOR TPS is one of important candidate structure of RLV. ARMOR thermal protection system in foreign countries for reusable launch vehicle is used instead of the traditional ceramic-matrix composite thermal protection system and C/C thermal protection system. Also the constituent feature of ARMOR thermal protection system is much better than the traditional TPS. In comparison with traditional TPS, the ARMOR TPS will be the best selection for all kinds of RLV. So the ARMOR thermal protection system will be used in aviation and spaceflight field more and more widely because of its much better performance. ARMOR TPS panel is above the whole ARMOR TPS, and the metal honeycomb sandwich structure is the surface of the ARMOR TPS panel. So the metal honeycomb sandwich structure plays an important role in the ARMOR TPS, while it bears the flight dynamic pressure and stands against the flight dynamic calefaction. The metal honeycomb sandwich structure is made using the technique of the whole braze welding. In the course of the vacuum high temperature braze welding, its surface will appear concave. The reasons which lead to the shortage are summarized and discussed. The difference of thermal expansion coefficient and pressure between the core and the panels may be the chief reasons. This paper will analyze the mechanics behavior of metal honeycomb sandwich structure in the course of the vacuum high temperature braze welding, then make sure the reasons and get a way to solve it. Haynes214 is a good material of face sheet at present. ? - TiAl and microlaminate materials are the candidate materials in the future.

  20. Topology optimization of pressure adaptive honeycomb for a morphing flap

    NASA Astrophysics Data System (ADS)

    Vos, Roelof; Scheepstra, Jan; Barrett, Ron

    2011-03-01

    The paper begins with a brief historical overview of pressure adaptive materials and structures. By examining avian anatomy, it is seen that pressure-adaptive structures have been used successfully in the Natural world to hold structural positions for extended periods of time and yet allow for dynamic shape changes from one flight state to the next. More modern pneumatic actuators, including FAA certified autopilot servoactuators are frequently used by aircraft around the world. Pneumatic artificial muscles (PAM) show good promise as aircraft actuators, but follow the traditional model of load concentration and distribution commonly found in aircraft. A new system is proposed which leaves distributed loads distributed and manipulates structures through a distributed actuator. By using Pressure Adaptive Honeycomb (PAH), it is shown that large structural deformations in excess of 50% strains can be achieved while maintaining full structural integrity and enabling secondary flight control mechanisms like flaps. The successful implementation of pressure-adaptive honeycomb in the trailing edge of a wing section sparked the motivation for subsequent research into the optimal topology of the pressure adaptive honeycomb within the trailing edge of a morphing flap. As an input for the optimization two known shapes are required: a desired shape in cruise configuration and a desired shape in landing configuration. In addition, the boundary conditions and load cases (including aerodynamic loads and internal pressure loads) should be specified for each condition. Finally, a set of six design variables is specified relating to the honeycomb and upper skin topology of the morphing flap. A finite-element model of the pressure-adaptive honeycomb structure is developed specifically tailored to generate fast but reliable results for a given combination of external loading, input variables, and boundary conditions. Based on two bench tests it is shown that this model correlates well to experimental results. The optimization process finds the skin and honeycomb topology that minimizes the error between the acquired shape and the desired shape in each configuration.

  1. Adhesion characterization and defect sizing of sandwich honeycomb composites.

    PubMed

    Ndiaye, Elhadji Barra; Maréchal, Pierre; Duflo, Hugues

    2015-09-01

    Defects may appear in composite structures during their life cycle. A 10MHz 128 elements phased array transducer was investigated to characterize join bonds and defects in sandwich honeycomb composite structures. An adequate focal law throughout the composite skin gives the ultrasonic dispersive properties of the composite skin and glue layer behind. The resulting B-scan cartographies allow characterizing locally the honeycomb adhesion. Experimental measurements are compared in good agreement with the Debye Series Method (DSM). In the processed C-scan image, flaws are detectable and measurable, localized both in the scanning plane and in the thickness of the composite skin. PMID:26138595

  2. Electrical transport measurements on honeycomb artificial spin ice.

    NASA Astrophysics Data System (ADS)

    Zeissler, Katharina; Chadha, Megha; Cohen, Lesley; Branford, Will; Functional Magnetism Group Team

    2014-03-01

    Artificial spin ice is a macroscopic playground for magnetically frustrated systems. We have previously shown that in a cobalt honeycomb artificial spin ice composed of 1 micron long nanowires there are unusual features in the magnetotransport below 50K. Here we explore the low temperature transport of equivalent artificial spin ice structures fabricated from permalloy. We discuss the extent to which the phenomenon is generic to the honeycomb artificial spin ice geometry and the effect of changing the constituent material on the onset temperature and the magnitude of the magnetotransport effect.

  3. Macroscopic degeneracy and emergent frustration in a honeycomb lattice magnet.

    PubMed

    Venderbos, Jörn W F; Daghofer, Maria; van den Brink, Jeroen; Kumar, Sanjeev

    2011-08-12

    Using a hybrid method based on fermionic diagonalization and classical Monte Carlo techniques, we investigate the interplay between itinerant and localized spins, with competing double- and superexchange interactions, on a honeycomb lattice. For moderate superexchange, a geometrically frustrated triangular lattice of hexagons forms spontaneously. For slightly larger superexchange a dimerized ground state is stable that has macroscopic degeneracy. The presence of these states on a nonfrustrated honeycomb lattice highlights novel phenomena in this itinerant electron system: emergent geometrical frustration and degeneracy related to a symmetry intermediate between local and global. PMID:21902411

  4. Structural properties of superplastically formed/diffusion-bonded orthogonally corrugated core sandwich plates

    NASA Technical Reports Server (NTRS)

    Ko, W. L.

    1980-01-01

    This paper describes a new superplastically formed/diffusion-bonded (SPF/DB) orthogonally corrugated sandwich structure, and presents formulae and the associated plots for evaluating the effective elastic constants for the core of this new sandwich structure. Comparison of structural properties of this new sandwich structure with the conventional honeycomb core sandwich structure was made under the condition of equal sandwich density. It was found that the SPF/DB orthogonally corrugated sandwich core has higher transverse shear stiffness than the conventional honeycomb sandwich core. However, the former has lower stiffness in the sandwich core thickness direction than the latter.

  5. Bio-inspired low frictional surfaces having micro-dimple arrays prepared with honeycomb patterned porous films as wet etching masks.

    PubMed

    Saito, Y; Yabu, H

    2015-01-27

    Some kinds of snakes have micro-dimple arrays on their skins and show low frictional properties. Cost-effective and simple preparation methods of surfaces having micro-dimple arrays without burrs have been required. In this study, micro-dimple arrays were successfully prepared on aluminum plates and pipes by using honeycomb patterned porous films as wet etching masks. Resulting surfaces having 5 and 8 ?m dimple diameters show low frictional coefficients compared with polished surfaces at a fluid lubrication regime. PMID:25547931

  6. Service evaluation of Aluminum-Brazed Titanium (ABTi) jet engine tailpipe extensions

    NASA Technical Reports Server (NTRS)

    Elrod, S. D.

    1982-01-01

    Aluminum-brazed titanium (ABTi) jet engine tailpipe extensions were evaluated in commercial service over a 3-year period. The purpose of the evaluation was to determine the corrosion resistance of ABTi in acoustic applications (i.e., honeycomb sandwich incorporating a perforated inner skin). The results showed that ABTi does not have acceptable corrosion resistance in acoustic applications under severe operating conditions, but may be acceptable for acoustic applications in less severe environments.

  7. Some considerations of the performance of two honeycomb gas path seal material systems

    NASA Technical Reports Server (NTRS)

    Bill, R. C.; Shiembob, L. T.

    1980-01-01

    A standard Hastelloy-X honeycomb material and a pack aluminide coated honeycomb material were evaluated as to their performance as labyrinth seal materials for aircraft gas turbine engines. Consideration from published literature was given to the fluid sealing characteristics of two honeycomb materials in labyrinth seal applications, and their rub characteristics, erosion resistance, and oxidation resistance were evaluated. The increased temperature potential of the coated honeycomb material compared to the uncoated standard could be achieved without compromising the honeycomb material's rub tolerance, although there was some penalty in terms of reduced erosion resistance.

  8. Honeycomb superlattice pattern in a dielectric barrier discharge in argon/air

    SciTech Connect

    Zhu, Ping; Dong, Lifang Yang, Jing; Gao, Yenan; Wang, Yongjie; Li, Ben

    2015-02-15

    We report on a honeycomb superlattice pattern in a dielectric barrier discharge in argon/air for the first time. It consists of hexagon lattice and honeycomb framework and bifurcates from a hexagon pattern as the applied voltage increases. A phase diagram of the pattern as a function of the gas component and gas pressure is presented. The instantaneous images show that the hexagon lattice and honeycomb framework are ignited in turn in each half voltage cycle. The honeycomb framework is composed of filaments ignited randomly. The spatiotemporal dynamics of honeycomb superlattice pattern is discussed by wall charges.

  9. Growth competition during glancing angle deposition of nanorod honeycomb arrays

    E-print Network

    Gall, Daniel

    Growth competition during glancing angle deposition of nanorod honeycomb arrays C. M. Zhou and D approximately constant with a fixed l/w ratio. This is attributed to an intercolumnar growth competition. The competitive growth mode during GLAD is caused by the oblique deposition angle that results in strong atomic

  10. Repair of honeycomb panels with welded breakaway studs

    NASA Technical Reports Server (NTRS)

    Bruce, D. F.

    1969-01-01

    Damaged metallic honeycomb panels can be repaired by drilling holes and welding breakaway studs to both facing sheets. Minimal heat required for welding reduces distortion of highly stressed panels. Repairs can be made without the use of doublers and with greater strength when doublers are used.

  11. Optimal Fractal-Like Hierarchical Honeycombs Ramin Oftadeh,1

    E-print Network

    Vaziri, Ashkan

    .e., zeroth) to fourth order hierarchical honeycombs fabricated using 3D printing. The physical thickness of the structures is constant, tn ¼ 2 mm, because of the limitations of the 3D printing. To maintain the structure simulation, scaling analysis, and experiments. The structural organization (a set of real numbers i

  12. Metal honeycomb to porous wireform substrate diffusion bond evaluation

    NASA Technical Reports Server (NTRS)

    Vary, A.; Moorhead, P. E.; Hull, D. R.

    1982-01-01

    Two nondestructive techniques were used to evaluate diffusion bond quality between a metal foil honeycomb and porous wireform substrate. The two techniques, cryographics and acousto-ultrasonics, are complementary in revealing variations of bond integrity and quality in shroud segments from an experimental aircraft turbine engine.

  13. 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.

  14. Commercial application of aluminum honeycomb and foam in load bearing tubular structures

    E-print Network

    Bartolucci, Stefano, 1976-

    2004-01-01

    Small dimension engineering tubular structures subjected to a complex load system are designed like hollow circular shells. For minimum weight design, the ratio between the shell radius and the thickness has to be as large ...

  15. Localization in quantum walks on a honeycomb network

    NASA Astrophysics Data System (ADS)

    Lyu, Changyuan; Yu, Luyan; Wu, Shengjun

    2015-11-01

    We systematically study the localization effect in discrete-time quantum walks on a honeycomb network and establish the mathematical framework. We focus on the Grover walk first and rigorously derive the limit form of the walker's state, showing it has a certain probability to be localized at the starting position. The relationship between localization and the initial coin state is concisely represented by a linear map. We also define and calculate the average probability of localization by generating random initial states. Further, coin operators varying with positions are considered and the sufficient condition for localization is discussed. We also similarly analyze another four-state Grover walk. Theoretical predictions are all in accord with numerical simulation results. Finally, our results are compared with previous works to demonstrate the unusual trapping effect of quantum walks on a honeycomb network, as well as the advantages of our method.

  16. Shape memory polymer filled honeycomb model and experimental validation

    NASA Astrophysics Data System (ADS)

    Beblo, R. V.; Puttmann, J. P.; Joo, J. J.; Reich, G. W.

    2015-02-01

    An analytical model predicting the in-plane Young’s and shear moduli of a shape memory polymer filled honeycomb composite is presented. By modeling the composite as a series of rigidly attached beams, the mechanical advantage of the load distributed on each beam by the infill is accounted for. The model is compared to currently available analytical models as well as experimental data. The model correlates extremely well with experimental data for empty honeycomb and when the polymer is above its glass transition temperature. Below the glass transition temperature, rule of mixtures is shown to be more accurate as bending is no longer the dominant mode of deformation. The model is also derived for directions other than the typical x and y allowing interpolation of the stiffness of the composite in any direction.

  17. Spin and the Honeycomb Lattice: Lessons from Graphene

    SciTech Connect

    Mecklenburg, Matthew; Regan, B. C.

    2011-03-18

    A model of electrons hopping from atom to atom in graphene's honeycomb lattice gives low-energy electronic excitations that obey a relation formally identical to a 2+1 dimensional Dirac equation. Graphene's spin equivalent, 'pseudospin', arises from the degeneracy introduced by the honeycomb lattice's two inequivalent atomic sites per unit cell. Previously it has been thought that the usual electron spin and the pseudospin indexing the graphene sublattice state are merely analogues. Here we show that the pseudospin is also a real angular momentum. This identification explains the suppression of electron backscattering in carbon nanotubes and the angular dependence of light absorption by graphene. Furthermore, it demonstrates that half-integer spin like that carried by the quarks and leptons can derive from hidden substructure, not of the particles themselves, but rather of the space in which these particles live.

  18. Electrospun honeycomb as nests for controlled osteoblast spatial organization.

    PubMed

    Nedjari, Salima; Eap, Sandy; Hébraud, Anne; Wittmer, Corinne R; Benkirane-Jessel, Nadia; Schlatter, Guy

    2014-11-01

    Honeycomb nanofibrous scaffolds were elaborated by electrospinning onto micro-patterned collectors either with poly(?-caprolactone) (PCL) or poly(D, L-lactic acid) (PLA). The unimodal distribution of fiber diameters, observed for PLA, led to relatively flat scaffolds; on the other hand, the bimodal distribution of PCL fiber diameters significantly increased the relief of the scaffolds' patterns due to the preferential deposition of the thick fiber portions on the walls of the collector's patterns via preferential electrostatic interaction. Finally, a biological evaluation demonstrated the effect of the scaffolds' relief on the spatial organization of MG63 osteoblast-like cells. Mimicking hemi-osteons, cell gathering was observed inside PCL honeycomb nests with a size ranging from 80 to 360 µm. PMID:25138713

  19. Vibroacoustic flexural properties of symmetric honeycomb sandwich panels with composite faces

    NASA Astrophysics Data System (ADS)

    Guillaumie, Laurent

    2015-05-01

    The vibroacoustic bending properties of honeycomb sandwich panels with composite faces are studied from the wavenumber modulus to the mechanical impedance, passing through the modal density. Numerical results extracted from finite element software computations are compared with analytical results. In both cases, the homogenization method is used to calculate the global properties of the sandwich panel. Since faces are made of composite material, the classical laminate theory serves as reference. With particular conditions used in the application for symmetric panels, the original orthotropic mechanical properties can be reduced simply to three parameters commonly used in vibroacoustic characterizations. These three parameters are the mass per unit area, the bending rigidity and the out-of-plane shear rigidity. They simultaneously govern the wavenumber modulus, the modal frequencies, the modal density and the mechanical impedance. For all of these vibroacoustic characterizations, a special frequency called the transition frequency separates two domains. In the first domain, below the transition frequency or for low frequencies, the orthotropic sandwich panel has a classical isotropic plate behavior. In the second domain, above the transition frequency or for high frequencies, the out-of-plane shear rigidity is very significant and changes the behavior. However, the results discussed are only valid up to a certain frequency which is determined by the thickness and out-of-plane shear stiffness of the honeycomb core, the thickness and the bending stiffness of the laminated face sheets and then the mass per unit area and bending stiffness of the total sandwich structure. All these parameters influence the final choice of model and simplifications presented. Experimental measurements of the bending wavenumber modulus and modal frequencies for our own application were carried out. In the vibroacoustic domain, the critical frequency is also an important frequency. It again depends on the mass per unit area, the bending rigidity and the out-of-plane shear rigidity. The experimental and numerical results of the article are reasonably in agreement with the analytical formula. They all confirm the changes in frequency through different boundary conditions around the panel. The analytical modal frequencies of rectangular sandwich panels with transverse shear, under simply supported boundary conditions are well known, but under free boundary conditions it is more difficult to predict them. For experiments, however, these latter conditions are the most common. We present, in this paper, an analytical formula that we have developed for the modal frequencies of such a panel under free boundary conditions. All parameters being controlled, it is possible from dynamic measurements and with a special process to identify some honeycomb and composite mechanical properties.

  20. Water ingress detection in honeycomb sandwich panels by passive infrared thermography using a high-resolution thermal imaging camera

    NASA Astrophysics Data System (ADS)

    Ibarra-Castanedo, C.; Brault, L.; Marcotte, F.; Genest, M.; Farley, V.; Maldague, X.

    2012-06-01

    Water ingress in honeycomb structures is of great concern for the civil and military aerospace industries. Pressure and temperature variations during take-off and landing produce considerable stress on aircraft structures, promoting moisture ingress (by diffusion through fibers or by direct ingress through voids, cracks or unsealed joints) into the core. The presence of water (or other fluids such as kerosene, hydraulic fluid and de-icing agents) in any of its forms (gas vapor, liquid or ice) promotes corrosion, cell breakage, and induce composite layer delaminations and skin disbonds. In this study, testing specimens were produced from unserviceable parts from military aircraft. In order to simulate atmospheric conditions during landing, selected core areas were filled with measured quantities of water and then frozen in a cold chamber. The specimens were then removed from the chamber and monitored for over 20 minutes as they warm up using a cooled high-resolution infrared camera. Results have shown that detection and quantification of water ingress on honeycomb sandwich structures by passive infrared thermography is possible using a HD mid-wave infrared cameras for volumes of water as low as 0.2 ml and from a distance as far as 20 m from the target.

  1. Order parameters from image analysis: a honeycomb example

    NASA Astrophysics Data System (ADS)

    Kaatz, Forrest H.; Bultheel, Adhemar; Egami, Takeshi

    2008-11-01

    Honeybee combs have aroused interest in the ability of honeybees to form regular hexagonal geometric constructs since ancient times. Here we use a real space technique based on the pair distribution function (PDF) and radial distribution function (RDF), and a reciprocal space method utilizing the Debye-Waller Factor (DWF) to quantify the order for a range of honeycombs made by Apis mellifera ligustica. The PDFs and RDFs are fit with a series of Gaussian curves. We characterize the order in the honeycomb using a real space order parameter, OP 3 , to describe the order in the combs and a two-dimensional Fourier transform from which a Debye-Waller order parameter, u, is derived. Both OP 3 and u take values from [0, 1] where the value one represents perfect order. The analyzed combs have values of OP 3 from 0.33 to 0.60 and values of u from 0.59 to 0.69. RDF fits of honeycomb histograms show that naturally made comb can be crystalline in a 2D ordered structural sense, yet is more ‘liquid-like’ than cells made on ‘foundation’ wax. We show that with the assistance of man-made foundation wax, honeybees can manufacture highly ordered arrays of hexagonal cells. This is the first description of honeycomb utilizing the Debye-Waller Factor, and provides a complete analysis of the order in comb from a real-space order parameter and a reciprocal space order parameter. It is noted that the techniques used are general in nature and could be applied to any digital photograph of an ordered array.

  2. Order parameters from image analysis: a honeycomb example.

    PubMed

    Kaatz, Forrest H; Bultheel, Adhemar; Egami, Takeshi

    2008-11-01

    Honeybee combs have aroused interest in the ability of honeybees to form regular hexagonal geometric constructs since ancient times. Here we use a real space technique based on the pair distribution function (PDF) and radial distribution function (RDF), and a reciprocal space method utilizing the Debye-Waller Factor (DWF) to quantify the order for a range of honeycombs made by Apis mellifera ligustica. The PDFs and RDFs are fit with a series of Gaussian curves. We characterize the order in the honeycomb using a real space order parameter, OP ( 3 ), to describe the order in the combs and a two-dimensional Fourier transform from which a Debye-Waller order parameter, u, is derived. Both OP ( 3 ) and u take values from [0, 1] where the value one represents perfect order. The analyzed combs have values of OP ( 3 ) from 0.33 to 0.60 and values of u from 0.59 to 0.69. RDF fits of honeycomb histograms show that naturally made comb can be crystalline in a 2D ordered structural sense, yet is more 'liquid-like' than cells made on 'foundation' wax. We show that with the assistance of man-made foundation wax, honeybees can manufacture highly ordered arrays of hexagonal cells. This is the first description of honeycomb utilizing the Debye-Waller Factor, and provides a complete analysis of the order in comb from a real-space order parameter and a reciprocal space order parameter. It is noted that the techniques used are general in nature and could be applied to any digital photograph of an ordered array. PMID:18633584

  3. Fabrication of prepackaged superalloy honeycomb Thermal Protection System (TPS) panels

    NASA Technical Reports Server (NTRS)

    Blair, W.; Meaney, J. E.; Rosenthal, H. A.

    1985-01-01

    High temperature materials were surveyed, and Inconel 617 and titanium were selected for application to a honeycomb TPS configuration designed to withstand 2000 F. The configuration was analyzed both thermally and structurally. Component and full-sized panels were fabricated and tested to obtain data for comparison with analysis. Results verified the panel design. Twenty five panels were delivered to NASA Langley Research Center for additional evaluation.

  4. Pressurized honeycombs as soft-actuators: a theoretical study.

    PubMed

    Guiducci, Lorenzo; Fratzl, Peter; Bréchet, Yves J M; Dunlop, John W C

    2014-09-01

    The seed capsule of Delosperma nakurense is a remarkable example of a natural hygromorph, which unfolds its protecting valves upon wetting to expose its seeds. The beautiful mechanism responsible for this motion is generated by a specialized organ based on an anisotropic cellular tissue filled with a highly swelling material. Inspired by this system, we study the mechanics of a diamond honeycomb internally pressurized by a fluid phase. Numerical homogenization by means of iterative finite-element (FE) simulations is adapted to the case of cellular materials filled with a variable pressure fluid phase. Like its biological counterpart, it is shown that the material architecture controls and guides the otherwise unspecific isotropic expansion of the fluid. Deformations up to twice the original dimensions can be achieved by simply setting the value of input pressure. In turn, these deformations cause a marked change of the honeycomb geometry and hence promote a stiffening of the material along the weak direction. To understand the mechanism further, we also developed a micromechanical model based on the Born model for crystal elasticity to find an explicit relation between honeycomb geometry, swelling eigenstrains and elastic properties. The micromechanical model is in good qualitative agreement with the FE simulations. Moreover, we also provide the force-stroke characteristics of a soft actuator based on the pressurized anisotropic honeycomb and show how the internal pressure has a nonlinear effect which can result in negative values of the in-plane Poisson's ratio. As nature shows in the case of the D. nakurense seed capsule, cellular materials can be used not only as low-weight structural materials, but also as simple but convenient actuating materials. PMID:24966238

  5. Thermal conductivity of Rene 41 honeycomb panels. [space transportation vehicles

    NASA Technical Reports Server (NTRS)

    Deriugin, V.

    1980-01-01

    Effective thermal conductivities of Rene 41 panels suitable for advanced space transportation vehicle structures were determined analytically and experimentally for temperature ranges between 20.4K (423 F) and 1186K (1675 F). The cryogenic data were obtained using a cryostat whereas the high temperature data were measured using a heat flow meter and a comparative thermal conductivity instrument respectively. Comparisons were made between analysis and experimental data. Analytical methods appear to provide reasonable definition of the honeycomb panel effective thermal conductivities.

  6. Arsenene: Two-dimensional buckled and puckered honeycomb arsenic systems

    NASA Astrophysics Data System (ADS)

    Kamal, C.; Ezawa, Motohiko

    2015-02-01

    Recently, phosphorene, a monolayer honeycomb structure of black phosphorus, was experimentally manufactured and has attracted rapidly growing interest. Motivated by phosphorene, here we investigate the stability and electronic properties of the honeycomb structure of the arsenic system based on first-principles calculations. Two types of honeycomb structures, buckled and puckered, are found to be stable. We call them arsenenes, as in the case of phosphorene. We find that both buckled and puckered arsenenes possess indirect gaps. We show that the band gap of puckered and buckled arsenenes can be tuned by applying strain. The gap closing occurs at 6% strain for puckered arsenene, where the bond angles between the nearest neighbors become nearly equal. An indirect-to-direct gap transition occurs by applying strain. Specifically, 1% strain is enough to transform puckered arsenene into a direct-gap semiconductor. We note that a bulk form of arsenic called gray arsenic exists which can be used as a precursor for buckled arsenene. Our results will pave the way for applications to light-emitting diodes and solar cells.

  7. Dynamical quantum phase transitions in the Kitaev honeycomb model

    NASA Astrophysics Data System (ADS)

    Schmitt, Markus; Kehrein, Stefan

    2015-08-01

    The notion of a dynamical quantum phase transition (DQPT) was recently introduced [Heyl et al., Phys. Rev. Lett. 110, 135704 (2013), 10.1103/PhysRevLett.110.135704] as the nonanalytic behavior of the Loschmidt echo at critical times in the thermodynamic limit. In this work the quench dynamics in the ground state sector of the two-dimensional Kitaev honeycomb model is studied regarding the occurrence of DQPTs. For general two-dimensional systems of BCS type it is demonstrated how the zeros of the Loschmidt echo coalesce to areas in the thermodynamic limit, implying that DQPTs occur as discontinuities in the second derivative. In the Kitaev honeycomb model DQPTs appear after quenches across a phase boundary or within the massless phase. In the 1d limit of the Kitaev honeycomb model it becomes clear that the discontinuity in the higher derivative is intimately related to the higher dimensionality of the nondegenerate model. Moreover, there is a strong connection between the stationary value of the rate function of the Loschmidt echo after long times and the occurrence of DQPTs in this model.

  8. Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel. Part 3; 8-ply Out-of-Autoclave Facesheets

    NASA Technical Reports Server (NTRS)

    Pineda, Evan J.; Myers, David E.; Kosareo, Daniel N.; Kellas, Sotiris

    2014-01-01

    Four honeycomb sandwich panels, representing 1/16th arc segments of a 10 m diameter barrel section of the heavy lift launch vehicle, were manufactured under the NASA Composites for Exploration program and the NASA Constellation Ares V program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: inautoclave IM7/977-3 and out-of-autoclave T40-800B/5320-1. Smaller 3- by 5-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center. Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of the 3- by 5-ft panels. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panel composed of 8-ply, T40-800B/5320-1 facesheets (referred to as Panel C). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear, two-dimensional (2-D) and three-dimensional (3-D), models yield good qualitative and quantitative predictions. Additionally, it was predicted correctly that the panel would fail in buckling prior to failing in strength.

  9. Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel: Comparison of In- and Out-of-Autoclave Facesheet Configurations

    NASA Technical Reports Server (NTRS)

    Pineda, Evan Jorge; Myers, David E.; Kosareo, Daniel N.; Zalewski, Bart F.; Kellas, Sotiris; Dixon, Genevieve D.; Krivanek, Thomas M.; Gyekenyesi, Thomas G.

    2014-01-01

    Four honeycomb sandwich panels, representing 1/16th arc segments of a 10-m diameter barrel section of the Heavy Lift Launch Vehicle, were manufactured and tested under the NASA Composites for Exploration and the NASA Constellation Ares V programs. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.0 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: in-autoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3 ft. by 5 ft. panels were cut from the 1/16th barrel sections and tested under compressive loading. Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of each 3 ft. by 5 ft. panel. To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yielded good qualitative and quantitative predictions. Additionally, it was correctly predicted that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber angle misalignments, and three-dimensional effects on the compressive response of the panel.

  10. Producing gapped-ferrite transformer cores

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T.

    1980-01-01

    Improved manufacturing techniques make reproducible gaps and minimize cracking. Molded, unfired transformer cores are cut with thin saw and then fired. Hardened semicircular core sections are bonded together, placed in aluminum core box, and fluidized-coated. After winding is run over box, core is potted. Economical method significantly reduces number of rejects.

  11. Aluminum and Young Artists.

    ERIC Educational Resources Information Center

    Anderson, Thomas

    1980-01-01

    The author suggests a variety of ways in which aluminum and aluminum foil can be used in elementary and junior high art classes: relief drawing and rubbing; printing; repousse; sculpture; mobiles; foil sculpture; and three dimensional design. Sources of aluminum supplies are suggested. (SJL)

  12. Computer simulation of screw dislocation in aluminum

    NASA Technical Reports Server (NTRS)

    Esterling, D. M.

    1976-01-01

    The atomic structure in a 110 screw dislocation core for aluminum is obtained by computer simulation. The lattice statics technique is employed since it entails no artificially imposed elastic boundary around the defect. The interatomic potential has no adjustable parameters and was derived from pseudopotential theory. The resulting atomic displacements were allowed to relax in all three dimensions.

  13. Hidden symmetry and protection of Dirac points on the honeycomb lattice.

    PubMed

    Hou, Jing-Min; Chen, Wei

    2015-01-01

    The honeycomb lattice possesses a novel energy band structure, which is characterized by two distinct Dirac points in the Brillouin zone, dominating most of the physical properties of the honeycomb structure materials. However, up till now, the origin of the Dirac points is unclear yet. Here, we discover a hidden symmetry on the honeycomb lattice and prove that the existence of Dirac points is exactly protected by such hidden symmetry. Furthermore, the moving and merging of the Dirac points and a quantum phase transition, which have been theoretically predicted and experimentally observed on the honeycomb lattice, can also be perfectly explained by the parameter dependent evolution of the hidden symmetry. PMID:26639178

  14. Hidden symmetry and protection of Dirac points on the honeycomb lattice

    PubMed Central

    Hou, Jing-Min; Chen, Wei

    2015-01-01

    The honeycomb lattice possesses a novel energy band structure, which is characterized by two distinct Dirac points in the Brillouin zone, dominating most of the physical properties of the honeycomb structure materials. However, up till now, the origin of the Dirac points is unclear yet. Here, we discover a hidden symmetry on the honeycomb lattice and prove that the existence of Dirac points is exactly protected by such hidden symmetry. Furthermore, the moving and merging of the Dirac points and a quantum phase transition, which have been theoretically predicted and experimentally observed on the honeycomb lattice, can also be perfectly explained by the parameter dependent evolution of the hidden symmetry. PMID:26639178

  15. Managing aluminum phosphide poisonings

    PubMed Central

    Gurjar, Mohan; Baronia, Arvind K; Azim, Afzal; Sharma, Kalpana

    2011-01-01

    Aluminum phosphide (AlP) is a cheap, effective and commonly used pesticide. However, unfortunately, it is now one of the most common causes of poisoning among agricultural pesticides. It liberates lethal phosphine gas when it comes in contact either with atmospheric moisture or with hydrochloric acid in the stomach. The mechanism of toxicity includes cellular hypoxia due to the effect on mitochondria, inhibition of cytochrome C oxidase and formation of highly reactive hydroxyl radicals. The signs and symptoms are nonspecific and instantaneous. The toxicity of AlP particularly affects the cardiac and vascular tissues, which manifest as profound and refractory hypotension, congestive heart failure and electrocardiographic abnormalities. The diagnosis of AlP usually depends on clinical suspicion or history, but can be made easily by the simple silver nitrate test on gastric content or on breath. Due to no known specific antidote, management remains primarily supportive care. Early arrival, resuscitation, diagnosis, decrease the exposure of poison (by gastric lavage with KMnO4, coconut oil), intensive monitoring and supportive therapy may result in good outcome. Prompt and adequate cardiovascular support is important and core in the management to attain adequate tissue perfusion, oxygenation and physiologic metabolic milieu compatible with life until the tissue poison levels are reduced and spontaneous circulation is restored. In most of the studies, poor prognostic factors were presence of acidosis and shock. The overall outcome improved in the last decade due to better and advanced intensive care management. PMID:21887030

  16. Nondestructive testing techniques used in analysis of honeycomb structure bond strength

    NASA Technical Reports Server (NTRS)

    Erdman, D. C.; Martin, G.; Moore, J. F.; Thomas, G.; Varney, H. S.

    1967-01-01

    DOT /Driver-Displacement Oriented Transducer/, applicable to both lap shear type application and honeycomb sandwich structures, measures the displacement of the honeycomb composite face sheet. It incorporates an electromagnetic driver and a displacement measuring system into a single unit to provide noncontact bond strength measurements.

  17. Emission of an intense electron beam from a ceramic honeycomb

    NASA Astrophysics Data System (ADS)

    Friedman, M.; Myers, M.; Hegeler, F.; Swanekamp, S. B.; Sethian, J. D.; Ludeking, L.

    2003-01-01

    Inserting a slab of honeycomb ceramic in front of the emitting surface of a large-area cathode improves the electron beam emission uniformity, decreases the beam current rise and fall times, and maintains a more constant diode impedance. Moreover, changing the cathode material from velvet to carbon fiber achieved a more robust cathode that starts to emit at a higher electric field without a degradation in beam uniformity. In addition, an 80% reduction in the postshot diode pressure was also observed when gamma alumina was deposited on the ceramic. A possible explanation is that reabsorption and recycling of adsorbed gases takes place.

  18. Quantum phase transition in the frustrated anisotropic honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Pires, A. S. T.

    2015-12-01

    We study the spin -1 Heisenberg antiferromagnet on the two dimensional honeycomb lattice at zero temperature, with nearest-neighbor J1 and next-to-nearest neighbor J2 exchange interactions and single-ion easy plane anisotropy, using the SU(3) Schwinger boson formalism. A disordered spin-liquid phase may appear in a narrow regime of intermediate frustration, in between an ordered antiferromagnetic phase and a collinear one. This quantum paramagnetic state is characterized by a finite gap in the excitation spectrum.

  19. Tight binding models for ultracold atoms in honeycomb optical lattices

    E-print Network

    Julen Ibañez-Azpiroz; Asier Eiguren; Aitor Bergara; Giulio Pettini; Michele Modugno

    2012-11-29

    We discuss how to construct tight-binding models for ultra cold atoms in honeycomb potentials, by means of the maximally localized Wannier functions (MLWFs) for composite bands introduced by Marzari and Vanderbilt [1]. In particular, we work out the model with up to third-nearest neighbors, and provide explicit calculations of the MLWFs and of the tunneling coefficients for the graphene-lyke potential with two degenerate minima per unit cell. Finally, we discuss the degree of accuracy in reproducing the exact Bloch spectrum of different tight-binding approximations, in a range of typical experimental parameters.

  20. Antiferromagnetic majority voter model on square and honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Sastre, Francisco; Henkel, Malte

    2016-02-01

    An antiferromagnetic version of the well-known majority voter model on square and honeycomb lattices is proposed. Monte Carlo simulations give evidence for a continuous order-disorder phase transition in the stationary state in both cases. Precise estimates of the critical point are found from the combination of three cumulants, and our results are in good agreement with the reported values of the equivalent ferromagnetic systems. The critical exponents 1 / ?, ? / ? and ? / ? were found. Their values indicate that the stationary state of the antiferromagnetic majority voter model belongs to the Ising model universality class.

  1. Protecting the Kitaev honeycomb model from external fields

    NASA Astrophysics Data System (ADS)

    Xu, Haitan; Taylor, Jacob

    2011-03-01

    We propose an approach to generate many-body interactions from two-body interactions with stable cat states. Applied to the celebrated Kitaev honeycomb model, our approach opens a spectral gap in the gapless phase of the model without any external magnetic field. We confirm the non-Abelian topological properties of a generalized Kitaev model and demonstrate our approach's robustness to sources of error. Our work provides a complete framework for experimentally realizing and manipulating non-Abelian anyons, with direct application in topological quantum computation. Supported by NSF JQI PFC.

  2. Magnetic Anisotropy of a Three-Dimensional Honeycomb Iridate

    NASA Astrophysics Data System (ADS)

    Modic, Kimberly; McDonald, Ross; Shekter, Arkady; Analytis, James; Ramshaw, Brad

    2015-03-01

    We present the magnetic anisotropy of a 3-dimensional honeycomb iridate, where the large spin-orbit coupling of iridium provides the possibility for exotic magnetic ground states. A complete angular dependence of magnetic torque provides evidence for highly spin-anisotropic exchange interactions at low temperature. An extension of these measurements to high magnetic fields shows that the magnetic anisotropy switches sign at 50 T and becomes five times larger than the anisotropy at low fields. The anisotropy continues to increase up to the largest applied fields suggesting the presence of new magnetically ordered states.

  3. CVD Growth of Self-Organized Micro-Honeycomb Network Structure of Single-Walled Carbon Nanotubes for Photovoltaic Devices

    E-print Network

    Maruyama, Shigeo

    CVD Growth of Self-Organized Micro-Honeycomb Network Structure of Single-Walled Carbon Nanotubes of dye-sensitized solar cells. Here, we propose a self-organized micro-honeycomb network structure performance. The SWNT/n-Si heterojunction solar cell was built by placing the micro-honeycomb SWNTs network

  4. Simulated effect on the compressive and shear mechanical properties of bionic integrated honeycomb plates.

    PubMed

    He, Chenglin; Chen, Jinxiang; Wu, Zhishen; Xie, Juan; Zu, Qiao; Lu, Yun

    2015-05-01

    Honeycomb plates can be applied in many fields, including furniture manufacturing, mechanical engineering, civil engineering, transportation and aerospace. In the present study, we discuss the simulated effect on the mechanical properties of bionic integrated honeycomb plates by investigating the compressive and shear failure modes and the mechanical properties of trabeculae reinforced by long or short fibers. The results indicate that the simulated effect represents approximately 80% and 70% of the compressive and shear strengths, respectively. Compared with existing bionic samples, the mass-specific strength was significantly improved. Therefore, this integrated honeycomb technology remains the most effective method for the trial manufacturing of bionic integrated honeycomb plates. The simulated effect of the compressive rigidity is approximately 85%. The short-fiber trabeculae have an advantage over the long-fiber trabeculae in terms of shear rigidity, which provides new evidence for the application of integrated bionic honeycomb plates. PMID:25746272

  5. Topological states in multi-orbital HgTe honeycomb lattices

    PubMed Central

    Beugeling, W.; Kalesaki, E.; Delerue, C.; Niquet, Y.-M.; Vanmaekelbergh, D.; Smith, C. Morais

    2015-01-01

    Research on graphene has revealed remarkable phenomena arising in the honeycomb lattice. However, the quantum spin Hall effect predicted at the K point could not be observed in graphene and other honeycomb structures of light elements due to an insufficiently strong spin–orbit coupling. Here we show theoretically that 2D honeycomb lattices of HgTe can combine the effects of the honeycomb geometry and strong spin–orbit coupling. The conduction bands, experimentally accessible via doping, can be described by a tight-binding lattice model as in graphene, but including multi-orbital degrees of freedom and spin–orbit coupling. This results in very large topological gaps (up to 35?meV) and a flattened band detached from the others. Owing to this flat band and the sizable Coulomb interaction, honeycomb structures of HgTe constitute a promising platform for the observation of a fractional Chern insulator or a fractional quantum spin Hall phase. PMID:25754462

  6. Annular honeycomb seals: Test results for leakage and rotordynamic coefficients; comparisons to labyrinth and smooth configurations

    NASA Technical Reports Server (NTRS)

    Childs, Dara W.; Elrod, David; Hale, Keith

    1989-01-01

    Test results are presented for leakage and rotordynamic coefficients for seven honeycomb seals. All seals have the same radius, length, and clearance; however, the cell depths and diameters are varied. Rotordynamic data, which are presented, consist of the direct and cross-coupled stiffness coefficients and the direct damping coefficients. The rotordynamic-coefficient data show a considerable sensitivity to changes in cell dimensions; however, no clear trends are identifiable. Comparisons of test data for the honeycomb seals with labyrinth and smooth annular seals show the honeycomb seal had the best sealing (minimum leakage) performance, followed in order by the labyrinth and smooth seals. For prerotated fluid entering the seal, in the direction of shaft rotation, the honeycomb seal has the best rotordynamic stability followed in order by the labyrinth and smooth. For no prerotation, or fluid prerotation against shaft rotation, the labyrinth seal has the best rotordynamic stability followed in order by the smooth and honeycomb seals.

  7. Annular honeycomb seals: Test results for leakage and rotordynamic coefficients - Comparisons to labyrinth and smooth configurations

    NASA Technical Reports Server (NTRS)

    Childs, D.; Elrod, D.; Hale, K.

    1989-01-01

    Test results are presented for leakage and rotordynamic coefficients for seven honeycomb seals. All seals have the same radius, length, and clearance; however, the cell depths and diameters are varied. Rotordynamic data, which are presented, consist of the direct and cross-coupled stiffness coefficients and the direct damping coefficients. The rotordynamic-coefficient data show a considerable sensitivity to changes in cell dimensions; however, no clear trends are identifiable. Comparisons of test data for the honeycomb seals with labyrinth and smooth annular seals shows the honeycomb seal had the best sealing (minimum leakage) performance, followed in order by the labyrinth and smooth seals. For prerotated fluids entering the seal, in the direction of shaft rotation, the honeycomb seal has the best rotordynamic stability followed in order by the labyrinth and smooth. For no prerotation, or fluid prerotation against shaft rotation, the labyrinth seal has the best rotordynamic stability followed in order by the smooth and honeycomb seals.

  8. Aspects of aluminum toxicity

    SciTech Connect

    Hewitt, C.D.; Savory, J.; Wills, M.R. )

    1990-06-01

    Aluminum is the most abundant metal in the earth's crust. The widespread occurrence of aluminum, both in the environment and in foodstuffs, makes it virtually impossible for man to avoid exposure to this metal ion. Attention was first drawn to the potential role of aluminum as a toxic metal over 50 years ago, but was dismissed as a toxic agent as recently as 15 years ago. The accumulation of aluminum, in some patients with chronic renal failure, is associated with the development of toxic phenomena; dialysis encephalopathy, osteomalacic dialysis osteodystrophy, and an anemia. Aluminum accumulation also occurs in patients who are not on dialysis, predominantly infants and children with immature or impaired renal function. Aluminum has also been implicated as a toxic agent in the etiology of Alzheimer's disease, Guamiam amyotrophic lateral sclerosis, and parkinsonism-dementia. 119 references.

  9. Scandium in aluminum alloys

    SciTech Connect

    Kramer, L.S.; Tack, W.T.; Fernandes, M.T.

    1997-10-01

    Aluminum alloys that contain dilute scandium additions display upgraded properties in several areas. In conjunction with zirconium, scandium forms very fine, coherent precipitates that impart strength and serve to inhibit recrystallization in aluminum alloys. In addition, these alloys display improved hot-cracking resistance during welding, and enhanced weld strength. Several scandium-aluminum alloys are currently under development, and some of the more interesting properties are presented in this article.

  10. Aluminum powder metallurgy processing

    SciTech Connect

    Flumerfelt, J.F.

    1999-02-12

    The objective of this dissertation is to explore the hypothesis that there is a strong linkage between gas atomization processing conditions, as-atomized aluminum powder characteristics, and the consolidation methodology required to make components from aluminum powder. The hypothesis was tested with pure aluminum powders produced by commercial air atomization, commercial inert gas atomization, and gas atomization reaction synthesis (GARS). A comparison of the GARS aluminum powders with the commercial aluminum powders showed the former to exhibit superior powder characteristics. The powders were compared in terms of size and shape, bulk chemistry, surface oxide chemistry and structure, and oxide film thickness. Minimum explosive concentration measurements assessed the dependence of explosibility hazard on surface area, oxide film thickness, and gas atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization processing conditions. The GARS aluminum powders were exposed to different relative humidity levels, demonstrating the effect of atmospheric conditions on post-atomization oxidation of aluminum powder. An Al-Ti-Y GARS alloy exposed in ambient air at different temperatures revealed the effect of reactive alloy elements on post-atomization powder oxidation. The pure aluminum powders were consolidated by two different routes, a conventional consolidation process for fabricating aerospace components with aluminum powder and a proposed alternative. The consolidation procedures were compared by evaluating the consolidated microstructures and the corresponding mechanical properties. A low temperature solid state sintering experiment demonstrated that tap densified GARS aluminum powders can form sintering necks between contacting powder particles, unlike the total resistance to sintering of commercial air atomization aluminum powder.

  11. Material Model Evaluation of a Composite Honeycomb Energy Absorber

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Annett, Martin S.; Fasanella, Edwin L.; Polanco, Michael A.

    2012-01-01

    A study was conducted to evaluate four different material models in predicting the dynamic crushing response of solid-element-based models of a composite honeycomb energy absorber, designated the Deployable Energy Absorber (DEA). Dynamic crush tests of three DEA components were simulated using the nonlinear, explicit transient dynamic code, LS-DYNA . In addition, a full-scale crash test of an MD-500 helicopter, retrofitted with DEA blocks, was simulated. The four material models used to represent the DEA included: *MAT_CRUSHABLE_FOAM (Mat 63), *MAT_HONEYCOMB (Mat 26), *MAT_SIMPLIFIED_RUBBER/FOAM (Mat 181), and *MAT_TRANSVERSELY_ANISOTROPIC_CRUSHABLE_FOAM (Mat 142). Test-analysis calibration metrics included simple percentage error comparisons of initial peak acceleration, sustained crush stress, and peak compaction acceleration of the DEA components. In addition, the Roadside Safety Verification and Validation Program (RSVVP) was used to assess similarities and differences between the experimental and analytical curves for the full-scale crash test.

  12. Triangular and honeycomb lattices of cold atoms in optical cavities

    NASA Astrophysics Data System (ADS)

    Safaei, Shabnam; Miniatura, Christian; Grémaud, Benoît.

    2015-10-01

    We consider a two-dimensional homogeneous ensemble of cold bosonic atoms loaded inside two optical cavities and pumped by a far-detuned external laser field. We examine the conditions for these atoms to self-organize into triangular and honeycomb lattices as a result of superradiance. By collectively scattering the pump photons, the atoms feed the initially empty cavity modes. As a result, the superposition of the pump and cavity fields creates a space-periodic light-shift external potential and atoms self-organize into the potential wells of this optical lattice. Depending on the phase of the cavity fields with respect to the pump laser, these minima can either form a triangular or a hexagonal lattice. By numerically solving the dynamical equations of the coupled atom-cavity system, we have shown that the two stable atomic structures at long times are the triangular lattice and the honeycomb lattice with equally populated sites. We have also studied how to drive atoms from one lattice structure to another by dynamically changing the phase of the cavity fields with respect to the pump laser.

  13. The Hamiltonian Laceability of some Generalized Honeycomb Tori

    SciTech Connect

    Hsu Liyen; Lin Tungyi; Kao Shinshin

    2008-11-06

    Assume that m, n and s are integers with m{>=}2, n{>=}4, 0{<=}s{<=}n and s is of the same parity of m. The generalized honeycomb torus GHT (m,n,s) is recognized as another attractive alternative to existing torus interconnection networks in parallel and distributed applications. It is known that any GHT (m,n,s) is 3-regular, hamiltonian, bipartite graph. We are interested in two special types of the generalized honeycomb torus, GHT (m,n,(n/2)) and GHT (m,n,0). Let G = GHT(m,n,s), where s(set-membership sign){l_brace}(n/2),0{r_brace}. We prove that any G is hamiltonian laceable. More precisely, given a pair of vertices P = {l_brace}u,v|u(set-membership sign)B,v(set-membership sign)W{r_brace} where B and W are the bipartition of V(G), there exists a path Q between u and v such that Q contains all vertices of G.

  14. Carbothermic Aluminum Production Using Scrap Aluminum As A Coolant

    DOEpatents

    LaCamera, Alfred F. (Trafford, PA)

    2002-11-05

    A process for producing aluminum metal by carbothermic reduction of alumina ore. Alumina ore is heated in the presence of carbon at an elevated temperature to produce an aluminum metal body contaminated with about 10-30% by wt. aluminum carbide. Aluminum metal or aluminum alloy scrap then is added to bring the temperature to about 900-1000.degree. C. and precipitate out aluminum carbide. The precipitated aluminum carbide is filtered, decanted, or fluxed with salt to form a molten body having reduced aluminum carbide content.

  15. Studies on aluminum neurotoxicity

    SciTech Connect

    Cho, S.

    1988-01-01

    This work reports the inhibitory effects of aluminum on glucose-6-phosphate dehydrogenase (G6PD) from yeast and brains. The aluminum contents and several enzyme activities in aluminum-fed rat brain homogenates were compared with those in age-matched control groups. The concentration of aluminum in the homogenates of the aluminum-fed groups were twice of that of the controls. Acetylcholinesterase activities were the same as in both groups but hexokinase and G6PD activities in the aluminum-fed group were about 73% and 70% of the control, respectively. Further studies on the inhibitory effects of aluminum on G6PD were performed with the enzymes purified from human and pig brains. Two forms of G6PD isozymes were purified from human and pig brain by ammonium sulfate fractionation, hydroxylapatite chromatography, affinity chromatography with NADP-agarose and Blue-Sepharose CL-6B, and gel filtration with Sephadex S-300. The two forms of isozymes (isozyme I and II), purified to be homogeneous, had a molecular weight of 220,000, and composed of 4 subunits of molecular weight of 57,000. HPLC peptide maps of tryptic digests and amino acid analyses of the isozymes showed extensive homologies between the isozymes. Interestingly, only the isozyme II in human and pig brain were active with 6-phosphogluconate as a substrate. No such an activity was found in isozyme I. Aluminum inactivated G6PD activity of the human and pig brain isozyme I and isozyme II without affecting the 6-phosphogluconate dehydrogenase activity of the isozyme II. Circular dichroism studies showed that the binding of aluminum to G6PD induced a decrease in {alpha}-helix and {beta}-sheet and a increase in random coil. Therefore it is suggested that inactivation of G6PD by aluminum is due to the conformational change induced by aluminum binding.

  16. Aluminum: Reducing chloride emissions from aluminum production

    SciTech Connect

    Simon, P.

    1999-09-29

    Reynolds Metals Company (RMC), with assistance from a NICE{sup 3} grant, is developing for commercialization a closed-loop control process that greatly reduces chlorine emissions and increases plant efficiency while maintaining metal quality. The process still utilizes chlorine to remove impurities during aluminum processing, but is more effective than current methods. With the new technology chlorine in the stack is monitored and input chlorine is adjusted continuously. This optimization of chlorine use results in substantially less waste because less chlorine has to be bought or produced by aluminum manufacturers. This innovation is a significant improvement over conventional aluminum treatments, in which chlorine is injected in a more costly and wasteful manner. By the year 2010, the new technology has the potential to reduce the energy it takes to create chlorine by 8.4 billion Btu per year and to cut greenhouse gas emissions by 1,377 tons per year.

  17. Is the Aluminum Hypothesis Dead?

    PubMed Central

    2014-01-01

    The Aluminum Hypothesis, the idea that aluminum exposure is involved in the etiology of Alzheimer disease, dates back to a 1965 demonstration that aluminum causes neurofibrillary tangles in the brains of rabbits. Initially the focus of intensive research, the Aluminum Hypothesis has gradually been abandoned by most researchers. Yet, despite this current indifference, the Aluminum Hypothesis continues to attract the attention of a small group of scientists and aluminum continues to be viewed with concern by some of the public. This review article discusses reasons that mainstream science has largely abandoned the Aluminum Hypothesis and explores a possible reason for some in the general public continuing to view aluminum with mistrust. PMID:24806729

  18. Anodizing Aluminum with Frills.

    ERIC Educational Resources Information Center

    Doeltz, Anne E.; And Others

    1983-01-01

    "Anodizing Aluminum" (previously reported in this journal) describes a vivid/relevant laboratory experience for general chemistry students explaining the anodizing of aluminum in sulfuric acid and constrasting it to electroplating. Additions to this procedure and the experiment in which they are used are discussed. Reactions involved are also…

  19. The morphology and functions of articular chondrocytes on a honeycomb-patterned surface.

    PubMed

    Eniwumide, Joshua O; Tanaka, Masaru; Nagai, Nobuhiro; Morita, Yuka; de Bruijn, Joost; Yamamoto, Sadaaki; Onodera, Shin; Kondo, Eiji; Yasuda, Kazunori; Shimomura, Masatsugu

    2014-01-01

    The present study investigated the potential of a novel micropatterned substrate for neocartilage formation. Articular chondrocytes were cultured on poly( ?-caprolactone) materials whose surfaces were either flat or honeycomb-patterned. The latter was prepared using a novel self-organization technique, while the former, was prepared by spin-coating. The chondrocytes attached and proliferated on both surfaces. On the honeycomb films, chondrocytes were found at the top surface and encased within the 10? ?m pores. Meanwhile, chondrocytes on the spin-coated surface flattened out. Accumulation of DNA and keratin sulphate was comparatively higher on the honeycomb films within the first 7 days. At their respective peaks, DNA concentration increased on the honeycomb and flat surfaces by approximately 210% and 400% of their day 1 values, respectively. However, cultures on the flat surface took longer to peak. Extracellular Matrix (ECM) concentrations peaked at 900% and 320% increases for the honeycomb and flat cultures. Type II collagen was upregulated on the honeycomb and flat surfaces by as much as 28% and 25% of their day 1 values, while aggrecan was downregulated with time, by 3.4% and 7.4%. These initial results demonstrate the potential usefulness of honeycomb-based scaffolds during early cultures neocartilage and soft tissue engineering. PMID:24804237

  20. Aluminum structural applications

    SciTech Connect

    Lucas, G.

    1996-05-01

    Extensive research by aluminum producers and automakers in the 1980s resulted in the development of technologies that enable building of aluminum cars that meet and exceed all the expectations of today`s drivers and passengers, yet weigh several hundred pounds less than their steel counterparts. The Acura NSX sports car, the Audi A8, and the Jaguar XJ220 have all been introduced. Ford has built 40 aluminum-intensive automobiles based on the Taurus/Sable for test purposes, and General Motors recently announced an aluminum-structured electric vehicle. The design flexibility that aluminum allows is shown by these examples. Each uses a somewhat different technology that is particularly suited to the vehicle and its market.

  1. The Aluminum Smelting Process

    PubMed Central

    2014-01-01

    This introduction to the industrial primary aluminum production process presents a short description of the electrolytic reduction technology, the history of aluminum, and the importance of this metal and its production process to modern society. Aluminum's special qualities have enabled advances in technologies coupled with energy and cost savings. Aircraft capabilities have been greatly enhanced, and increases in size and capacity are made possible by advances in aluminum technology. The metal's flexibility for shaping and extruding has led to architectural advances in energy-saving building construction. The high strength-to-weight ratio has meant a substantial reduction in energy consumption for trucks and other vehicles. The aluminum industry is therefore a pivotal one for ecological sustainability and strategic for technological development. PMID:24806722

  2. Evaluation of Composite Honeycomb Sandwich Panels Under Compressive Loads at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Walker, Sandra P.

    1998-01-01

    Fourteen composite honeycomb sandwich panels were tested to failure under compressive loading. The test specimens included panels with both 8 and 24-ply graphite-bismaleimide composite facesheets and both titanium and graphite-polyimide core materials. The panels were designed to have the load introduced through fasteners attached to pairs of steel angles on the ends of the panels to simulate double shear splice joints. The unloaded edges were unconstrained. Test temperatures included room temperature, 250F, and 300F. For the room and 250F temperature tests, the 24-ply specimen failure strains were close to the unnotched allowable strain values and failure loads were well above the design loads. However, failure strains much lower than the unnotched allowable strain values, and failure loads below the design loads were observed with several of the 8-ply specimens. For each individual test temperature, large variations in the failure strains and loads were observed for the 8-ply specimens. Dramatic decreases in the failure strains and loads were observed for the 24-ply specimens as the test temperature was increased from 250F to 300F. All 8-ply specimens appeared to have failed in a facesheet strength failure mode for all test temperatures. The 24-ply specimens displayed appreciably greater amounts of bending prior to failure than the 8-ply specimens, and panel buckling occurred prior to facesheet strength failure for the 24-ply room and 250F temperature tests.

  3. Chiral spin liquid in the frustrated XY model on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Sedrakyan, Tigran

    2015-03-01

    A honeycomb lattice allowing hops between nearest- and next-nearest neighbors hosts ``moat'' bands with degenerate energy minima attained along closed lines in Brillouin zone. If populated with hard-core bosons, a variety of unconventional ground states stabilizes. We argue that the degeneracy prevents Bose condensation, stabilizing novel spin liquid phases including composite fermion state and a chiral spin liquid. The latter stabilizes at half-filling, when the system is equivalent to s = 1 / 2 XY model at zero magnetic field. Absence of condensation means no spontaneous polarization in XY plane, however our consideration indicates formation of a state spontaneously breaking the time-reversal symmetry. This state has a bulk gap and chiral gapless edge excitations, and is similar to the one in Haldane's ``quantum Hall effect without Landau levels'' in its topologically nontrivial sector with Chen number C = +/- 1 . The applications of the developed analytical theory include an explanation of recent unexpected numerical findings and a suggestion of a chiral spin liquid realization in experiments with cold atoms in optical lattices.

  4. Diffusion bonded boron/aluminum spar-shell fan blade

    NASA Technical Reports Server (NTRS)

    Carlson, C. E. K.; Cutler, J. L.; Fisher, W. J.; Memmott, J. V. W.

    1980-01-01

    Design and process development tasks intended to demonstrate composite blade application in large high by-pass ratio turbofan engines are described. Studies on a 3.0 aspect radio space and shell construction fan blade indicate a potential weight savings for a first stage fan rotor of 39% when a hollow titanium spar is employed. An alternate design which featured substantial blade internal volume filled with titanium honeycomb inserts achieved a 14% potential weight savings over the B/M rotor system. This second configuration requires a smaller development effort and entails less risk to translate a design into a successful product. The feasibility of metal joining large subsonic spar and shell fan blades was demonstrated. Initial aluminum alloy screening indicates a distinct preference for AA6061 aluminum alloy for use as a joint material. The simulated airfoil pressings established the necessity of rigid air surfaces when joining materials of different compressive rigidities. The two aluminum alloy matrix choices both were successfully formed into blade shells.

  5. Interpretation of Cp(*) - protected Aluminum Clusters as Superatom Complexes

    NASA Astrophysics Data System (ADS)

    Clayborne, P. Andre; Lopez-Acevedo, Olga; Whetten, Robert; Grönbeck, Henrik; Häkkinen, Hannu

    2011-03-01

    Metal clusters stabilized by a surface ligand shell represent an interesting intermediate state of matter between molecular metal-ligand complexes and bulk metal. Such ``metalloid'' particles are characterized by the balance between metal-metal bonds in the core and metal-ligand bonds at the exterior of the cluster. In previous studies, the electronic stability observed for selected ligand-protected aluminum clusters is not fully understood. By density functional theory calculations, we illustrate here that the electronic stability of various experimentally isolated Cp(*) -- protected aluminum clusters can be explained using the electron shell model for the aluminum core, coupled with an ionic Al-Cp(*) interaction at the surface. Thus, one may classify ligand-protected aluminum clusters as ``superatom complexes'' similar to the ligand-protected gold clusters. Financial support by the Academy of Finland. The computational resources were provided by the CSC - the Finnish IT Center for Science in Espoo.

  6. Modulation of the photonic band structure topology of a honeycomb lattice in an atomic vapor

    NASA Astrophysics Data System (ADS)

    Zhang, Yiqi; Liu, Xing; Beli?, Milivoj R.; Wu, Zhenkun; Zhang, Yanpeng

    2015-12-01

    In an atomic vapor, a honeycomb lattice can be constructed by utilizing the three-beam interference method. In the method, the interference of the three beams splits the dressed energy level periodically, forming a periodic refractive index modulation with the honeycomb profile. The energy band topology of the honeycomb lattice can be modulated by frequency detunings, thereby affecting the appearance (and disappearance) of Dirac points and cones in the momentum space. This effect can be usefully exploited for the generation and manipulation of topological insulators.

  7. Modulation of the photonic band structure topology of a honeycomb lattice in an atomic vapor

    E-print Network

    Zhang, Yiqi; Beli?, Milivoj R; Wu, Zhenkun; Zhang, Yanpeng

    2015-01-01

    In an atomic vapor, a honeycomb lattice can be constructed by utilizing the three-beam interference method. In the method, the interference of the three beams splits the dressed energy level periodically, forming a periodic refractive index modulation with the honeycomb profile. The energy band topology of the honeycomb lattice can be modulated by frequency detunings, thereby affecting the appearance (and disappearance) of Dirac points and cones in the momentum space. This effect can be usefully exploited for the generation and manipulation of topological insulators.

  8. Aluminum monocarbonyl and aluminum isocarbonyl Steve S. Wesolowski,a)

    E-print Network

    Crawford, T. Daniel

    Aluminum monocarbonyl and aluminum isocarbonyl Steve S. Wesolowski,a) T. Daniel Crawford,b) Justin of the aluminum monocarbonyl species AlCO and AlOC have been performed to predict the geometries, fragmentation, Ogden, and Oswald6 first isolated aluminum dicarbonyls in solid krypton and identified the species

  9. Degassing of Aluminum Alloys Using Ultrasonic Vibration

    SciTech Connect

    Meek, T. T.; Han, Q.; Xu, H.

    2006-06-01

    The research was intended to lead to a better fundamental understanding of the effect of ultrasonic energy on the degassing of liquid metals and to develop practical approaches for the ultrasonic degassing of alloys. The goals of the project described here were to evaluate core principles, establish a quantitative basis for the ultrasonic degassing of aluminum alloy melts, and demonstrate the application of ultrsaonic processing during ingot casting and foundry shape casting.

  10. On the honeycomb conjecture and the Kepler problem

    E-print Network

    Fu-Gao Song; Francis Austin

    2009-07-25

    This paper views the honeycomb conjecture and the Kepler problem essentially as extreme value problems and solves them by partitioning 2-space and 3-space into building blocks and determining those blocks that have the universal extreme values that one needs. More precisely, we proved two results. First, we proved that the regular hexagons are the only 2-dim blocks that have unit area and the least perimeter (or contain a unit circle and have the least area) that tile the plane. Secondly, we proved that the rhombic dodecahedron and the rhombus-isosceles trapezoidal dodecahedron are the only two 3-dim blocks that contain a unit sphere and have the least volume that can fill 3-space without either overlapping or leaving gaps. Finally, the Kepler conjecture can also be proved to be true by introducing the concept of the minimum 2-dim and 3-dim Kepler building blocks.

  11. Flat Bands and Wigner Crystallization in the Honeycomb Optical Lattice

    SciTech Connect

    Wu Congjun; Bergman, Doron; Balents, Leon; Das Sarma, S.

    2007-08-17

    We study the ground states of cold atoms in the tight-binding bands built from p orbitals on a two dimensional honeycomb optical lattice. The band structure includes two completely flat bands. Exact many-body ground states with on-site repulsion can be found at low particle densities, for both fermions and bosons. We find crystalline order at n=(1/6) with a {radical}(3)x{radical}(3) structure breaking a number of discrete lattice symmetries. In fermionic systems, if the repulsion is strong enough, we find the bonding strength becomes dimerized at n=(1/2). Experimental signatures of crystalline order can be detected through the noise correlations in time of flight experiments.

  12. Sound Transmission Through a Curved Honeycomb Composite Panel

    NASA Technical Reports Server (NTRS)

    Klos, Jacob; Robinson, Jay H.; Buehrle, Ralph D.

    2003-01-01

    Composite structures are often used in aircraft because of the advantages offered by a high strength to weight ratio. However, the acoustical properties of these light and stiff structures can often be less than desirable resulting in high aircraft interior noise levels. In this paper, measurements and predictions of the transmission loss of a curved honeycomb composite panel are presented. The transmission loss predictions are validated by comparisons to measurements. An assessment of the behavior of the panel is made from the dispersion characteristics of transverse waves propagating in the panel. The speed of transverse waves propagating in the panel is found to be sonic or supersonic over the frequency range from 100 to 5000 Hz. The acoustical benefit of reducing the wave speed for transverse vibration is demonstrated.

  13. Correlated spinless fermions on the honeycomb lattice revisited

    NASA Astrophysics Data System (ADS)

    Scherer, Daniel D.; Scherer, Michael M.; Honerkamp, Carsten

    2015-10-01

    We investigate the quantum many-body instabilities of the extended Hubbard model for spinless fermions on the honeycomb lattice with repulsive nearest-neighbor and second-nearest-neighbor density-density interactions. Recent exact diagonalization and infinite density matrix renormalization group results suggest that a putative topological Mott insulator phase driven by the second-nearest-neighbor repulsion is suppressed, while other numerically exact approaches support the topological Mott insulator scenario. In the present work, we employ the functional renormalization group (fRG) for correlated fermionic systems. Our fRG results hint at a strong suppression of the scattering processes stabilizing the topological Mott insulator. From analyzing the effects of fermionic fluctuations, we obtain a phase diagram, which is the result of the competition of various charge ordering instabilities.

  14. Kane-Mele-Hubbard model on the ?-flux honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Bercx, Martin; Hohenadler, Martin; Assaad, Fakher F.

    2014-08-01

    We consider the Kane-Mele-Hubbard model with a magnetic ? flux threading each honeycomb plaquette. The resulting model has remarkably rich physical properties. In each spin sector, the noninteracting band structure is characterized by a total Chern number C =±2. Fine-tuning of the intrinsic spin-orbit coupling ? leads to a quadratic band crossing point associated with a topological phase transition. At this point, quantum Monte Carlo simulations reveal a magnetically ordered phase that extends to weak coupling. Although the spinful model has two Kramers doublets at each edge and is explicitly shown to be a Z2 trivial insulator, the helical edge states are protected at the single-particle level by translation symmetry. Drawing on the bosonized low-energy Hamiltonian, we predict a correlation-induced gap as a result of umklapp scattering for half-filled bands. For strong interactions, this prediction is confirmed by quantum Monte Carlo simulations.

  15. Microstructural design of cellular materials. 1: Honeycomb beams and plates

    SciTech Connect

    Huang, J.S.; Gibson, L.J.

    1995-04-01

    Performance indices for materials describe the mechanical efficiency of a component under a given mode of loading: the higher the performance index, the lower the mass of the component for a given mechanical requirement. Material selection charts offer a graphical means of comparing performance indices for a wide range of materials. The performance indices are first described. Micromechanical models for the behavior of cellular materials are then used to suggest novel microstructural designs for cellular materials with improved performance. Model materials with two of the microstructures, honeycomb beams and plates, have been fabricated and tested. The results of the tests indicate that the new microstructures have higher values of some performance indices than those of the solids from which they are made.

  16. PUBLISHED ONLINE: 14 MARCH 2010 | DOI: 10.1038/NPHYS1615 Band dispersion in the deep 1s core level

    E-print Network

    Loss, Daniel

    LETTERS PUBLISHED ONLINE: 14 MARCH 2010 | DOI: 10.1038/NPHYS1615 Band dispersion in the deep 1s * It is generally assumed that electrons in deep atomic core states are highly localized and do not participate of the C 1s core level in graphene, a single-layer honeycomb net of carbon atoms that is attracting

  17. Clinical biochemistry of aluminum

    SciTech Connect

    King, S.W.; Savory, J.; Wills, M.R.

    1981-05-01

    Aluminum toxicity has been implicated in the pathogenesis of a number of clinical disorders in patients with chronic renal failure on long-term intermittent hemodialysis treatment. The predominant disorders have been those involving either bone (osteomalacic dialysis osteodystrophy) or brain (dialysis encephalopathy). In nonuremic patients, an increased brain aluminum concentration has been implicated as a neurotoxic agent in the pathogenesis of Alzheimer's disease and was associated with experimental neurofibrillary degeneration in animals. The brain aluminum concentrations of patients dying with the syndrome of dialysis encephalopathy (dialysis dementia) are significantly higher than in dialyzed patients without the syndrome and in nondialyzed patients. Two potential sources for the increased tissue content of aluminum in patients on hemodialysis have been proposed: (1) intestinal absorption from aluminum containing phosphate-binding gels, and (2) transfer across the dialysis membrane from aluminum in the water used to prepare the dialysate. These findings, coupled with our everyday exposure to the ubiquitous occurrence of aluminum in nature, have created concerns over the potential toxicity of this metal.

  18. Two Dimensional Honeycomb Materials: random fields, dissipation and fluctuations

    E-print Network

    T. Frederico; O. Oliveira; W. de Paula; M. S. Hussein; T. R. Cardoso

    2015-12-13

    In this paper, we propose a method to describe the many-body problem of electrons in honeycomb materials via the introduction of random fields which are coupled to the electrons and have a Gaussian distribution. From a one-body approach to the problem, after integrating exactly the contribution of the random fields, one builds a non-hermitian and dissipative effective Hamiltonian with two-body interactions. Our approach introduces besides the usual average over the electron field a second average over the random fields. The interplay of two averages enables the definition of various types of Green's functions which allow the investigation of fluctuation-dissipation characteristics of the interactions that are a manifestation of the many-body problem. In the current work we study only the dissipative term, through the perturbative analysis of the dynamics associated the effective Hamiltonian generated by two different kinds of couplings. For the cases analysed, the eigenstates of the effective Hamiltonian are complex and, therefore, some of the states have a finite life time. Moreover, we also investigate, in the mean field approximation, the most general parity conserving coupling to the random fields and compute the width of charge carriers $\\Gamma$ as a function of the Fermi energy $E_F$. The theoretical prediction for $\\Gamma (E_F)$ is compared to the available experimental data for graphene. The good agreement between $\\Gamma_{theo}$ and $\\Gamma_{exp}$ suggests that description of the many-body problem associated to the electrons in honeycomb materials can indeed be done via the introduction of random fields.

  19. Aluminum-halogen cells

    SciTech Connect

    Arakawa, T.; Fukuoka, M.; Kimura, M.; Kobayashi, H.; Masukawa, Y.

    1981-05-26

    An aluminum-halogen cell is disclosed that is comprised of aluminum as an anode active material and a halogen compound as a cathode active material characterized in that the layer containing the cathode active material further comprises at least one stabilizer selected from the group consisting of magnesium halides, zinc halides, organic carboxylic acids and their anhydrides, aluminum or more basic metallic salts of perhaloid acids and quaternary ammonium salts shows only slight lowering in output voltage at initial discharge when continuously discharged under a load and can give high discharge output for a remarkably long period of time.

  20. Purifying Aluminum by Vacuum Distillation

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.

    1985-01-01

    Proposed method for purifying aluminum employs one-step vacuum distillation. Raw material for process impure aluminum produced in electrolysis of aluminum ore. Impure metal melted in vacuum. Since aluminum has much higher vapor pressure than other constituents, boils off and condenses on nearby cold surfaces in proportions much greater than those of other constituents.

  1. Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel. Part 2; 6-Ply In-Autoclave Facesheets

    NASA Technical Reports Server (NTRS)

    Pineda, Evan J.; Meyers, David E.; Kosareo, Daniel N.; Zalewski, Bart F.; Dixon, Genevieve D.

    2013-01-01

    Four honeycomb sandwich panel types, representing 1/16th arc segments of a 10-m diameter barrel section of the Heavy Lift Launch Vehicle (HLLV), were manufactured and tested under the NASA Composites for Exploration program and the NASA Constellation Ares V program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: in-autoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3- by 5-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center (LaRC). Furthermore, linear eigenvalue and geometrically nonlinear finite element analyses were performed to predict the compressive response of each 3- by 5-ft panel. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panels composed of 6-ply, IM7/977-3 facesheets (referred to as Panels B-1 and B-2). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yield good qualitative and quantitative predictions. Additionally, it was correctly predicted that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber angle misalignments, and three-dimensional (3-D) effects on the compressive response of the panel.

  2. 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 ...

  3. Study on moisture absorption and sweat discharge of honeycomb polyester fiber

    NASA Astrophysics Data System (ADS)

    Feng, Aifen; Zhang, Yongjiu

    2015-07-01

    The moisture absorption and liberation properties of honeycomb polyester fiber were studied in order to understand its moisture absorption and sweat discharge. Through testing moisture absorption and liberation regains of honeycomb polyester fiber and normal polyester fiber in standard atmospheric conditions, their moisture absorption and liberation curves were depicted, and the regression equations of moisture regains to time during their reaching the balance of moisture absorption and moisture liberation were obtained according to the curves. Their moisture absorption and liberation rate curves were analyzed and the regression equations of the rates to time were obtained. The results shows that the moisture regain of honeycomb polyester fiber is much bigger than the normal polyester fiber's, and the initial moisture absorption and moisture liberation rates of the former are much higher than the latter's, so that the moisture absorbance and sweat discharge of honeycomb polyester fiber are excellent.

  4. A study of the effects of eccentricity on honeycomb annular gas seals 

    E-print Network

    Weatherwax, Mark

    2001-01-01

    Results are presented which show the effects of eccentricity on high pressure honeycomb and smooth annular gas seals. The results of the experiments indicate the ability to utilize centered seal solutions for rotordynamic coefficients and seal...

  5. Mechanical properties of the hierarchical honeycombs with stochastic Voronoi sub-structures

    NASA Astrophysics Data System (ADS)

    Du, Yinghong; Pugno, Nicola; Gong, Baoming; Wang, Dongpo; Sun, Yongtao; Ding, Qian

    2015-09-01

    The introduction of hierarchy into structures has been credited with changing mechanical properties. In this study, periodically hierarchical honeycomb with irregular sub-structure cells has been designed based on the Voronoi tessellation algorithm. Numerical investigation has been performed to determine the influence of structural hierarchy and irregularity on the in-plane elastic properties. Irregular hierarchical honeycombs can be up to 3 times stiffer than regular hexagonal honeycombs on an equal density basis. Both the stiffness and Poisson's ratio of the hierarchical honeycomb are insensitive to the degree of regularity, and depend on the cell-wall thickness-to-length ratio of the super-structure. Increasing the relative lengths of the super- and sub-structures results in the increment of Young's modulus, whereas Poisson's ratio almost remains constant varying from 1.0 to 0.7.

  6. Walnut Hulls Clean Aluminum

    NASA Technical Reports Server (NTRS)

    Colberg, W. R.; Gordon, G. H.; Jackson, C. H.

    1984-01-01

    Hulls inflict minimal substrate damage. Walnut hulls found to be best abrasive for cleaning aluminum surfaces prior to painting. Samples blasted with walnut hulls showed no compressive stress of surface.

  7. Advances in aluminum anodizing

    NASA Technical Reports Server (NTRS)

    Dale, K. H.

    1969-01-01

    White anodize is applied to aluminum alloy surfaces by specific surface preparation, anodizing, pigmentation, and sealing techniques. The development techniques resulted in alloys, which are used in space vehicles, with good reflectance values and excellent corrosive resistance.

  8. Corrosion Inhibitors for Aluminum.

    ERIC Educational Resources Information Center

    Muller, Bodo

    1995-01-01

    Describes a simple and reliable test method used to investigate the corrosion-inhibiting effects of various chelating agents on aluminum pigments in aqueous alkaline media. The experiments that are presented require no complicated or expensive electronic equipment. (DDR)

  9. Alloying of liquid aluminum

    SciTech Connect

    Shafyei, A.; Guthrie, R.I.L.

    1996-10-01

    The addition of high melting point alloying elements is an integral component in the processing of molten aluminum alloys. In this research, the kinetics of dissolution of manganese and iron particles, freely dispersed in turbulently-stirred baths of liquid aluminum, has been investigated at a laboratory scale. First, the suspension behavior of alloying elements in liquid aluminum was studied via water modeling analogues, using dimensional analysis and similarity techniques. Second, mass transfer coefficients between particles of manganese or iron and stirred liquid aluminum were measured. These high temperature experiments showed that measured mass transfer coefficients of manganese and iron particles were strongly dependent on the intensity of the mixing, until the point at which particles became fully suspended. Further increases in the rate of mixing produced little further rises in mass transfer coefficients. From a practical point of view, therefore, these results suggested that very high rates of melt mixing are not recommended during an alloying process.

  10. A damage tolerance comparison of 7075-T6 aluminum alloy and IM7/977-2 carbon/epoxy

    NASA Technical Reports Server (NTRS)

    Nettles, Alan T.; Lance, David G.; Hodge, Andrew J.

    1991-01-01

    A comparison of low velocity impact damage between one of the strongest aluminum alloys, to a new, damage tolerant resin system as a matrix for high strength carbon fibers was examined in this study. The aluminum and composite materials were used as face sheets on a 0.13 g/cu cm aluminum honeycomb. Four levels of impact energy were used; 2.6 J, 5.3 J, 7.8 J and 9.9 J. The beams were compared for static strength and fatique life by use of the four-point bend flexure test. It was found that in the undamaged state the specific strength of the composite face sheets was about twice that of the aluminum face sheets. A sharp drop in strength was observed for the composite specimens impacted at the lowest (2.6J) energy level, but the overall specific strength was still higher than for the aluminum specimens. At all impact energy levels tested, the static specific strength of the composite face sheets were significantly higher than the aluminum face sheets. The fatigue life of the most severely damaged composite specimen was about 17 times greater than the undamaged aluminum specimens when cycled at 1 Hz between 20 percent and 85 percent of ultimate breaking load.

  11. Aluminum powder applications

    SciTech Connect

    Gurganus, T.B.

    1995-08-01

    Aluminum powders have physical and metallurgical characteristics related to their method of manufacture that make them extremely important in a variety of applications. They can propel rockets, improve personal hygiene, increase computer reliability, refine exotic alloys, and reduce weight in the family sedan or the newest Air Force fighter. Powders formed into parts for structural and non-structural applications hold the key to some of the most exciting new developments in the aluminum future.

  12. One-to-One Embedding between Honeycomb Mesh and Petersen-Torus Networks

    PubMed Central

    Seo, Jung-Hyun; Sim, Hyun; Park, Dae-Heon; Park, Jang-Woo; Lee, Yang-Sun

    2011-01-01

    As wireless mobile telecommunication bases organize their structure using a honeycomb-mesh algorithm, there are many studies about parallel processing algorithms like the honeycomb mesh in Wireless Sensor Networks. This paper aims to study the Peterson-Torus graph algorithm in regard to the continuity with honeycomb-mesh algorithm in order to apply the algorithm to sensor networks. Once a new interconnection network is designed, parallel algorithms are developed with huge research costs to use such networks. If the old network is embedded in a newly designed network, a developed algorithm in the old network is reusable in a newly designed network. Petersen-Torus has been designed recently, and the honeycomb mesh has already been designed as a well-known interconnection network. In this paper, we propose a one-to-one embedding algorithm for the honeycomb mesh (HMn) in the Petersen-Torus PT(n,n), and prove that dilation of the algorithm is 5, congestion is 2, and expansion is 5/3. The proposed one-to-one embedding is applied so that processor throughput can be minimized when the honeycomb mesh algorithm runs in the Petersen-Torus. PMID:22319392

  13. Effect of honeycomb seals on loss characteristics in shroud cavities of an axial turbine

    NASA Astrophysics Data System (ADS)

    Gao, Jie; Zheng, Qun; Wang, Zheng

    2013-01-01

    The loss in efficiency due to shroud leakage or tip clearance flow accounts for a substantial part of the overall losses in turbomachinery. It is important to identify the leakage loss characteristics in order to optimize turbomachinery. At present, little information is available in the open literature concerning the effect of honeycomb seals on the loss characteristics in shroud cavities of an axial turbine, despite of the widespread use of the honeycomb seals. Therefore, interaction between rotor labyrinth seal leakage flow with and without honeycomb facings and main flow is investigated to provide the loss characteristics of the mixing process of the re-entering leakage flow into the main flow. The effects of honeycomb seals on the flow in shroud cavities and interaction with the main flow are analyzed. An additional study on the impact of subtle shroud cavity exit geometry is also presented. The investigation results indicate that the honeycomb seal affects the over tip leakage flow and reduces mixing losses when compared to the solid labyrinth seal. The leakage flow interactions with the main flow have considerably changed the flow fields in the endwall regions. The proposed research reveals the effects of honeycomb seals on the loss characteristics in shroud cavities and the impact of subtle shroud cavity exit geometry, and it is helpful for the design optimization of turbomachinery.

  14. Novel Aharonov-Bohm-like effect: Detectability of the vector potential in a solenoidal configuration with a ferromagnetic core covered by superconducting lead, and surrounded by a thin cylindrical shell of aluminum

    E-print Network

    R. Y. Chiao

    2012-06-23

    The flux as measured by the Josephson effect in a SQUID-like configuration with a ferromagnetic core inserted into its center, is shown to be sensitive to the vector potential arising from the central ferromagnetic core, even when the core is covered with a superconducting material that prevents any magnetic field lines from ever reaching the perimeter of the SQUID-like configuration. This leads to a macroscopic, Aharonov-Bohm-like effect that is observable in an asymmetric hysteresis loop in the response of the SQUID-like configuration to an externally applied magnetic field.

  15. Aluminum, parathyroid hormone, and osteomalacia

    SciTech Connect

    Burnatowska-Hledin, M.A.; Kaiser, L.; Mayor, G.H.

    1983-01-01

    Aluminum exposure in man is unavoidable. The occurrence of dialysis dementia, vitamin D-resistant osteomalacia, and hypochromic microcytic anemia in dialysis patients underscores the potential for aluminum toxicity. Although exposure via dialysate and hyperalimentation leads to significant tissue aluminum accumulation, the ubiquitous occurrence of aluminum and the severe pathology associated with large aluminum burdens suggest that smaller exposures via the gastrointestinal tract and lungs could represent an important, though largely unrecognized, public health problem. It is clear that some aluminum absorption occurs with the ingestion of small amounts of aluminum in the diet and medicines, and even greater aluminum absorption is seen in individuals consuming large amounts of aluminum present in antacids. Aluminum absorption is enhanced in the presence of elevated circulating parathyroid hormone. In addition, elevated PTH leads to the preferential deposition of aluminum in brain and bone. Consequently, PTH is likely to be involved in the pathogenesis of toxicities in those organs. PTH excess also seems to lead to the deposition of aluminum in the parathyroid gland. The in vitro demonstration that aluminum inhibits parathyroid hormone release is consistent with the findings of a euparathyroid state in dialysis patients with aluminum related vitamin D-resistant osteomalacia. Nevertheless, it seems likely that hyperparathyroidism is at least initially involved in the pathogenesis of aluminum neurotoxicity and osteomalacia; the increases in tissue aluminum stores are followed by suppression of parathyroid hormone release, which is required for the evolution of osteomalacia. Impaired renal function is not a prerequisite for increased tissue aluminum burdens, nor for aluminum-related organ toxicity. Consequently, it is likely that these diseases will be observed in populations other than those with chronic renal disease.

  16. Monitoring of non-uniform strains and progressive damage in honeycomb skin by complex Bragg reflection spectrum analysis

    NASA Astrophysics Data System (ADS)

    Lu, Jiyun; Bian, Kan; Liang, Dakai; Liu, Shulin

    2015-07-01

    An analysis method of spectrum was proposed to assess the damage of honeycomb structures. The non-homogeneous strain fields of honeycomb cell walls were obtained by finite element analysis when tension was applied on the honeycomb structures. Spectrum changes of FBG sensors stuck on the cell walls were monitored and analyzed. Our analysis revealed that spectral bandwidth was broadened from 1nm to 3.5nm and spectrum was split to 12 peaks. The changes of light intensity of secondary peak corresponded to inflection points of load-displacement curves. The regular variations of spectrum were able to indicate progressive damage of honeycomb structures.

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

    E-print Network

    Vaziri, Ashkan

    and Industrial Engineering, Northeastern University, Boston, MA 02115, USA c Department of Mechanical and Industrial Engineering, Qatar University, Doha, Qatar a r t i c l e i n f o Article history: Available online foam [1,2], corrugated [3,4] and honeycomb cores [5] with close-cells cannot accommodate free fluid

  18. Bloch-Zener oscillations in a tunable optical honeycomb lattice

    SciTech Connect

    Uehlinger, Thomas; Greif, Daniel; Jotzu, Gregor; Esslinger, Tilman; Tarruell, Leticia

    2013-12-04

    Ultracold gases in optical lattices have proved to be a flexible tool to simulate many different phenomena of solid state physics [1, 2]. Recently, optical lattices with complex geometries have been realized [3, 4, 5, 6, 7], paving the way to simulating more realistic systems. The honeycomb structure has recently become accessible in an optical lattice composed of mutually perpendicular laser beams. This lattice structure exhibits topological features in its band structure – the Dirac points. At these points, two energy bands intersect linearly and the particles behave as relativistic Dirac fermions. In optical lattices, Bloch oscillations [8] resolved both in time and in quasi-momentum space can be directly observed. We make use of such Bloch-Zener oscillations to probe the vanishing energy gap at the Dirac points as well as their position in the band structure. In small band gap regions, we observe Landau-Zener tunneling [7, 9] to the second band and the regions of maximum transfer can be identified with the position of the Dirac points.

  19. Dirac-like plasmons in honeycomb lattices of metallic nanoparticles.

    PubMed

    Weick, Guillaume; Woollacott, Claire; Barnes, William L; Hess, Ortwin; Mariani, Eros

    2013-03-01

    We consider a two-dimensional honeycomb lattice of metallic nanoparticles, each supporting a localized surface plasmon, and study the quantum properties of the collective plasmons resulting from the near-field dipolar interaction between the nanoparticles. We analytically investigate the dispersion, the effective Hamiltonian, and the eigenstates of the collective plasmons for an arbitrary orientation of the individual dipole moments. When the polarization points close to the normal to the plane, the spectrum presents Dirac cones, similar to those present in the electronic band structure of graphene. We derive the effective Dirac Hamiltonian for the collective plasmons and show that the corresponding spinor eigenstates represent Dirac-like massless bosonic excitations that present similar effects to electrons in graphene, such as a nontrivial Berry phase and the absence of backscattering off smooth inhomogeneities. We further discuss how one can manipulate the Dirac points in the Brillouin zone and open a gap in the collective plasmon dispersion by modifying the polarization of the localized surface plasmons, paving the way for a fully tunable plasmonic analogue of graphene. PMID:23521276

  20. Dirac-Like Plasmons in Honeycomb Lattice of Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Woollacott, Claire; Weick, Guillaume; Barnes, William L.; Hess, Ortwin; Mariani, Eros

    2014-03-01

    We consider a two-dimensional (2D) honeycomb array of metallic nanoparticles, each supporting a localized surface plasmon, and study the quantum properties of the collective plasmonic modes resulting from the near-field dipole interaction between nanoparticles. We analytically investigate the dispersion, effective Hamiltonian and eigenstates of the collective plasmons for an arbitrary orientation of the individual dipole moments. For polarization pointing normal to the plane, the spectrum presents Dirac cones similar to those present in the electronic band structure of graphene. The effective Dirac Hamiltonian and corresponding spinor eigenstates represent Dirac-like massless bosonic excitation, presenting similar effects to electrons in graphene, for example, non-trivial Berry phase and the absence of backscattering off smooth inhomogeneities. However, by tilting the polarisation, the Dirac points can be manipulated and a gap can be controllably opened in the spectrum. Therefore the properties of this metamaterial can be manipulated by the incident light polarization, paving the way for a fully tunable plasmonic analogue of graphene. - G. Weick, C. Woollacott, W. Barnes, O. Hess and E. Mariani, Phys. Rev. Lett. 110, 106801 (2013)

  1. Dirac-like Plasmons in Honeycomb Lattices of Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Weick, Guillaume; Woollacott, Claire; Barnes, William L.; Hess, Ortwin; Mariani, Eros

    2013-03-01

    We consider a two-dimensional honeycomb lattice of metallic nanoparticles, each supporting a localized surface plasmon, and study the quantum properties of the collective plasmons resulting from the near-field dipolar interaction between the nanoparticles. We analytically investigate the dispersion, the effective Hamiltonian, and the eigenstates of the collective plasmons for an arbitrary orientation of the individual dipole moments. When the polarization points close to the normal to the plane, the spectrum presents Dirac cones, similar to those present in the electronic band structure of graphene. We derive the effective Dirac Hamiltonian for the collective plasmons and show that the corresponding spinor eigenstates represent Dirac-like massless bosonic excitations that present similar effects to electrons in graphene, such as a nontrivial Berry phase and the absence of backscattering off smooth inhomogeneities. We further discuss how one can manipulate the Dirac points in the Brillouin zone and open a gap in the collective plasmon dispersion by modifying the polarization of the localized surface plasmons, paving the way for a fully tunable plasmonic analogue of graphene.

  2. Majorana edge modes in Kitaev model on honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Thakurathi, Manisha; Sengupta, Krishnendu; Sen, Diptiman

    2015-03-01

    We study the Majorana modes, both equilibrium and Floquet, which can appear at the edges of the Kitaev model on the honeycomb lattice. We first present the analytical solutions known for the equilibrium Majorana edge modes for both zigzag and armchair edges of a semi-infinite Kitaev model and chart the parameter regimes of the model in which they appear. We then examine how edge modes can be generated if the Kitaev coupling on the bonds perpendicular to the edge is varied periodically in time as periodic ?-function kicks. We derive a general condition for the appearance and disappearance of the Floquet edge modes as a function of the drive frequency for a generic d-dimensional integrable system. We confirm this general condition for the Kitaev model with a finite width by mapping it to a one-dimensional model. Our numerical and analytical study of this problem shows that Floquet Majorana modes can appear on some edges in the kicked system even when the corresponding equilibrium Hamiltonian has no Majorana mode solutions on those edges. We support our analytical studies by numerics for finite sized system which show that periodic kicks can generate modes at the edges and the corners of the lattice. We thank CSIR, India and DST, India for financial support.

  3. Monomer-dimer problem on random planar honeycomb lattice

    SciTech Connect

    Ren, Haizhen; Department of Mathematics, Qinghai Normal University, Xining 810008, Qinghai ; Zhang, Fuji; Qian, Jianguo

    2014-02-15

    We consider the monomer-dimer (MD) problem on a random planar honeycomb lattice model, namely, the random multiple chain. This is a lattice system with non-periodic boundary condition, whose generating process is inspired by the growth of single walled zigzag carbon nanotubes. By applying algebraic and combinatorial techniques we establish a calculating expression of the MD partition function for bipartite graphs, which corresponds to the permanent of a matrix. Further, by using the transfer matrix argument we show that the computing problem of the permanent of high order matrix can be converted into some lower order matrices for this family of lattices, based on which we derive an explicit recurrence formula for evaluating the MD partition function of multiple chains and random multiple chains. Finally, we analyze the expectation of the number of monomer-dimer arrangements on a random multiple chain and the asymptotic behavior of the annealed MD entropy when the multiple chain becomes infinite in width and length, respectively.

  4. Magnetic Susceptibility and Quantum Oscillations in a Buckled Honeycomb Lattice

    NASA Astrophysics Data System (ADS)

    Tabert, Calvin; Carbotte, Jules; Nicol, Elisabeth

    2015-03-01

    We calculate the magnetic response of a low-buckled honeycomb lattice with intrinsic spin-orbit coupling which is described by the Kane-Mele Hamiltonian (a model which would describe the low-energy physics of a material like silicene). Included in the Hamiltonian, is a sublattice potential difference term which may be induced by a perpendicular electric field; this field can tune the system from a topological insulator (TI), through a valley-spin polarized metal, to a trivial band insulator (BI). In an external magnetic field, a distinct signature of the phase transition is seen in the derivative of the magnetization with respect to chemical potential; this gives the quantization of the Hall plateaus through the Streda relation. The results are compared with the zero-frequency conductivity obtained from the Kubo formula. The magnetic susceptibility also displays signatures of the different topological phases. We also explore the de-Haas van-Alphen effect. At the transition point between the TI and BI, magnetic oscillations exist for any value of chemical potential. Away from the critical point, the chemical potential must be larger than the minimum gap. For large chemical potential (or small but finite sublattice potential difference), there is a strong beating pattern.

  5. ALUMINUM RECLAMATION BY ACIDIC EXTRACTION OF ALUMINUM-ANODIZING SLUDGES

    EPA Science Inventory

    Extraction of aluminum-anodizing sludges with sulfuric acid was examined to determine the potential for production of commercial-strength solutions of aluminum sulfate, that is liquid alum. The research established kinetic and stoichiometric relationships and evaluates product qu...

  6. Heat Shield Employing Cured Thermal Protection Material Blocks Bonded in a Large-Cell Honeycomb Matrix

    NASA Technical Reports Server (NTRS)

    Zell, Peter

    2012-01-01

    A document describes a new way to integrate thermal protection materials on external surfaces of vehicles that experience the severe heating environments of atmospheric entry from space. Cured blocks of thermal protection materials are bonded into a compatible, large-cell honeycomb matrix that can be applied on the external surfaces of the vehicles. The honeycomb matrix cell size, and corresponding thermal protection material block size, is envisioned to be between 1 and 4 in. (.2.5 and 10 cm) on a side, with a depth required to protect the vehicle. The cell wall thickness is thin, between 0.01 and 0.10 in. (.0.025 and 0.25 cm). A key feature is that the honeycomb matrix is attached to the vehicle fs unprotected external surface prior to insertion of the thermal protection material blocks. The attachment integrity of the honeycomb can then be confirmed over the full range of temperature and loads that the vehicle will experience. Another key feature of the innovation is the use of uniform-sized thermal protection material blocks. This feature allows for the mass production of these blocks at a size that is convenient for quality control inspection. The honeycomb that receives the blocks must have cells with a compatible set of internal dimensions. The innovation involves the use of a faceted subsurface under the honeycomb. This provides a predictable surface with perpendicular cell walls for the majority of the blocks. Some cells will have positive tapers to accommodate mitered joints between honeycomb panels on each facet of the subsurface. These tapered cells have dimensions that may fall within the boundaries of the uniform-sized blocks.

  7. Aluminum for plasmonics.

    PubMed

    Knight, Mark W; King, Nicholas S; Liu, Lifei; Everitt, Henry O; Nordlander, Peter; Halas, Naomi J

    2014-01-28

    Unlike silver and gold, aluminum has material properties that enable strong plasmon resonances spanning much of the visible region of the spectrum and into the ultraviolet. This extended response, combined with its natural abundance, low cost, and amenability to manufacturing processes, makes aluminum a highly promising material for commercial applications. Fabricating Al-based nanostructures whose optical properties correspond with theoretical predictions, however, can be a challenge. In this work, the Al plasmon resonance is observed to be remarkably sensitive to the presence of oxide within the metal. For Al nanodisks, we observe that the energy of the plasmon resonance is determined by, and serves as an optical reporter of, the percentage of oxide present within the Al. This understanding paves the way toward the use of aluminum as a low-cost plasmonic material with properties and potential applications similar to those of the coinage metals. PMID:24274662

  8. Aluminum Hydroxide and Magnesium Hydroxide

    MedlinePLUS

    Aluminum Hydroxide, Magnesium Hydroxide are antacids used together to relieve heartburn, acid indigestion, and upset stomach. They may be used to ... with stomach acid and neutralize it. Aluminum Hydroxide, Magnesium Hydroxide are available without a prescription.This medication ...

  9. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan (Mastic, NY); Reilly, James J. (Bellport, NY)

    2009-04-21

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  10. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan; Reilly, James J; Wegrzyn, James E

    2012-09-18

    The present invention provides methods and materials for the formation of hydrogen storage alanes, AlH.sub.x, where x is greater than 0 and less than or equal to 6 at reduced H.sub.2 pressures and temperatures. The methods rely upon reduction of the change in free energy of the reaction between aluminum and molecular H.sub.2. The change in free energy is reduced by lowering the entropy change during the reaction by providing aluminum in a state of high entropy, and by increasing the magnitude of the change in enthalpy of the reaction or combinations thereof.

  11. Design optimization of sinusoidal glass honeycomb for flat plate solar collectors

    NASA Technical Reports Server (NTRS)

    Mcmurrin, J. C.; Buchberg, H.

    1980-01-01

    The design of honeycomb made of sinusoidally corrugated glass strips was optimized for use in water-cooled, single-glazed flat plate solar collectors with non-selective black absorbers. Cell diameter (d), cell height (L), and pitch/diameter ratio (P/d) maximizing solar collector performance and cost effectiveness for given cell wall thickness (t sub w) and optical properties of glass were determined from radiative and convective honeycomb characteristics and collector performance all calculated with experimentally validated algorithms. Relative lifetime values were estimated from present materials costs and postulated production methods for corrugated glass honeycomb cover assemblies. A honeycomb with P/d = 1.05, d = 17.4 mm, L = 146 mm and t sub w = 0.15 mm would provide near-optimal performance over the range delta T sub C greater than or equal to 0 C and less than or equal to 80 C and be superior in performance and cost effectiveness to a non-honeycomb collector with a 0.92/0.12 selective black absorber.

  12. Porous and Microporous Honeycomb Composites as Potential Boundary-Layer Bleed Materials

    NASA Technical Reports Server (NTRS)

    Davis, D. O.; Willis, B. P.; Schoenenberger, M.

    1997-01-01

    Results of an experimental investigation are presented in which the use of porous and microporous honeycomb composite materials is evaluated as an alternate to perforated solid plates for boundary-layer bleed in supersonic aircraft inlets. The terms "porous" and "microporous," respectively, refer to bleed orifice diameters roughly equal to and much less than the displacement thickness of the approach boundary-layer. A Baseline porous solid plate, two porous honeycomb, and three microporous honeycomb configurations are evaluated. The performance of the plates is characterized by the flow coefficient and relative change in boundary-layer profile parameters across the bleed region. The tests were conducted at Mach numbers of 1.27 and 1.98. The results show the porous honeycomb is not as efficient at removing mass compared to the baseline. The microporous plates were about equal to the baseline with one plate demonstrating a significantly higher efficiency. The microporous plates produced significantly fuller boundary-layer profiles downstream of the bleed region for a given mass flow removal rate than either the baseline or the porous honeycomb plates.

  13. Design optimization of sinusoidal glass honeycomb for flat plate solar collectors

    NASA Astrophysics Data System (ADS)

    McMurrin, J. C.; Buchberg, H.

    1980-08-01

    The design of honeycomb made of sinusoidally corrugated glass strips was optimized for use in water-cooled, single-glazed flat plate solar collectors with non-selective black absorbers. Cell diameter (d), cell height (L), and pitch/diameter ratio (P/d) maximizing solar collector performance and cost effectiveness for given cell wall thickness (t sub w) and optical properties of glass were determined from radiative and convective honeycomb characteristics and collector performance all calculated with experimentally validated algorithms. Relative lifetime values were estimated from present materials costs and postulated production methods for corrugated glass honeycomb cover assemblies. A honeycomb with P/d = 1.05, d = 17.4 mm, L = 146 mm and t sub w = 0.15 mm would provide near-optimal performance over the range delta T sub C greater than or equal to 0 C and less than or equal to 80 C and be superior in performance and cost effectiveness to a non-honeycomb collector with a 0.92/0.12 selective black absorber.

  14. Development of a Computer simulation approach for honeycomb constructions for aerospace application

    NASA Astrophysics Data System (ADS)

    Tatarnikov, O. V.; Karpenkov, K. S.

    2015-02-01

    An approach to definition of a homogeneous simulation model for honeycomb structures has been developed and verified for specimens containing a finite number of cells. The elastic characteristics of the model were evaluated basing on the results of tensile and shear numerical tests of honeycomb specimen. This is an extension of earlier work related with spatially reinforced composites. The simulation model was validated for specimens comprised of different numbers of cells in the specimen to expose the scale effect influence. As the number of cells was increased, the calculated values of the moduli Ex and Ey converged, confirming the theoretical result that the appropriate model is transversely isotropic rather than orthotropic for the honeycomb specimen investigated. Elastic properties obtained from the numerical test of the honeycomb structure were then applied in the characterization of continuous medium. The examination was carried out using criteria expressing basic features of homogeneous body. The case of a honeycomb integrated with composite plates as a sandwich structure was analysed for a complex loading case as well as buckling and eigen- frequency analysis.

  15. RECLAMATION OF ALUMINUM FINISHING SLUDGES

    EPA Science Inventory

    The research study of the reclamation of aluminum-anodizing sludges was conducted in two sequential phases focused on enhanced dewatering of aluminum-anodizing sludges to produce commercial-strength solutions of aluminum sulfate, i.e., liquid alum. The use of high-pressure (14 to...

  16. Electrically conductive anodized aluminum coatings

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S. (Inventor); Liu, Yanming (Inventor)

    2001-01-01

    A process for producing anodized aluminum with enhanced electrical conductivity, comprising anodic oxidation of aluminum alloy substrate, electrolytic deposition of a small amount of metal into the pores of the anodized aluminum, and electrolytic anodic deposition of an electrically conductive oxide, including manganese dioxide, into the pores containing the metal deposit; and the product produced by the process.

  17. Aluminum battery alloys

    DOEpatents

    Thompson, D.S.; Scott, D.H.

    1984-09-28

    Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  18. Mechanisms of aluminum tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aluminum (Al) toxicity limits agricultural productivity over much of the world’s arable land by inhibiting root growth and development. Affected plants have difficulty in acquiring adequate water and nutrition from their soil environments and thus have stunted shoot development and diminished yield....

  19. Aluminum battery alloys

    DOEpatents

    Thompson, David S. (Richmond, VA); Scott, Darwin H. (Mechanicsville, VA)

    1985-01-01

    Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

  20. Maize aluminum tolerance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Maize is one of the most economically important food crops grown on acid soils, where aluminum (Al) toxicity greatly limits crop yields. Considerable variation for Al tolerance exists in maize, and this variation has been exploited for many years by plant breeders to enhance maize Al tolerance. Curr...

  1. Aluminum Sulfate 18 Hydrate

    ERIC Educational Resources Information Center

    Young, Jay A.

    2004-01-01

    A chemical laboratory information profile (CLIP) of the chemical, aluminum sulfate 18 hydrate, is presented. The profile lists physical and harmful properties, exposure limits, reactivity risks, and symptoms of major exposure for the benefit of teachers and students using the chemical in the laboratory.

  2. Holes Localized on a Skyrmion in a Doped Antiferromagnet on the Honeycomb Lattice: Symmetry Analysis

    E-print Network

    Vlasii, N D; Jiang, F -J; Wiese, U -J

    2014-01-01

    Using the low-energy effective field theory for hole-doped antiferromagnets on the honeycomb lattice, we study the localization of holes on Skyrmions, as a potential mechanism for the preformation of Cooper pairs. In contrast to the square lattice case, for the standard radial profile of the Skyrmion on the honeycomb lattice, only holes residing in one of the two hole pockets can get localized. This differs qualitatively from hole pairs bound by magnon exchange, which is most attractive between holes residing in different momentum space pockets. On the honeycomb lattice, magnon exchange unambiguously leads to $f$-wave pairing, which is also observed experimentally. Using the collective-mode quantization of the Skyrmion, we determine the quantum numbers of the localized hole pairs. Again, $f$-wave symmetry is possible, but other competing pairing symmetries cannot be ruled out.

  3. Thermal behavior of laboratory models of honeycomb-covered solar ponds

    NASA Astrophysics Data System (ADS)

    Lin, E. I. H.

    Laboratory experiments were conducted to provide insight into the technical feasibility of honeycomb-covered solar ponds. Cooling tests using honeycomb panels of various materials and geometries showed that a 5.7-cm-thick one-tier panel insulated as effectively as a 10-cm fiberglass slab. Heating tests demonstrated that a model pond covered with a polycarbonate panel boiled upon 16 hours of continuous exposure to a 150-W spotlight. Analysis of the experimental data indicates positively that honeycomb-covered solar ponds can be expected to perform satisfactorily, and that larger-scale outdoor tests should be conducted to provide a more realistic assessment and a more refined performance estimate.

  4. Development of beryllium honeycomb sandwich composite for structural and other related applications

    NASA Technical Reports Server (NTRS)

    Vogan, J. W.; Grant, L. A.

    1972-01-01

    The feasibility of fabricating large beryllium honeycomb panels was demonstrated. Both flat and curved sandwich structures were manufactured using practical, braze bonding techniques. The processes developed prove that metallurgically assembled beryllium honeycomb panels show decided potential where rigid, lightweight structures are required. Three panels, each 10 square feet in surface area, were fabricated, and radiographically inspected to determine integrity. This examination revealed a 97 percent braze in the final panel. It is believed that ceramic dies for forming and brazing would facilitate the fabrication techniques for higher production rates. Ceramic dies would yield a lower thermal gradient in the panel during the braze cycle. This would eliminate the small amount of face sheet wrinkling present in the panels. Hot forming the various panel components demonstrated efficient manufacturing techniques for scaling up and producing large numbers of hot formed beryllium components and panels. The beryllium honeycomb panel demonstrated very good vibrational loading characteristics under test with desirable damping characteristics.

  5. Development and utilization of composite honeycomb and solid laminate reference standards for aircraft inspections.

    SciTech Connect

    Roach, Dennis Patrick; Rackow, Kirk A.

    2004-06-01

    The FAA's Airworthiness Assurance NDI Validation Center, in conjunction with the Commercial Aircraft Composite Repair Committee, developed a set of composite reference standards to be used in NDT equipment calibration for accomplishment of damage assessment and post-repair inspection of all commercial aircraft composites. In this program, a series of NDI tests on a matrix of composite aircraft structures and prototype reference standards were completed in order to minimize the number of standards needed to carry out composite inspections on aircraft. Two tasks, related to composite laminates and non-metallic composite honeycomb configurations, were addressed. A suite of 64 honeycomb panels, representing the bounding conditions of honeycomb construction on aircraft, was inspected using a wide array of NDI techniques. An analysis of the resulting data determined the variables that play a key role in setting up NDT equipment. This has resulted in a set of minimum honeycomb NDI reference standards that include these key variables. A sequence of subsequent tests determined that this minimum honeycomb reference standard set is able to fully support inspections over the full range of honeycomb construction scenarios found on commercial aircraft. In the solid composite laminate arena, G11 Phenolic was identified as a good generic solid laminate reference standard material. Testing determined matches in key velocity and acoustic impedance properties, as well as, low attenuation relative to carbon laminates. Furthermore, comparisons of resonance testing response curves from the G11 Phenolic NDI reference standard was very similar to the resonance response curves measured on the existing carbon and fiberglass laminates. NDI data shows that this material should work for both pulse-echo (velocity-based) and resonance (acoustic impedance-based) inspections.

  6. Combination of plasma with a honeycomb-structured catalyst for automobile exhaust treatment.

    PubMed

    Kang, Woo Seok; Lee, Dae Hoon; Lee, Jae-Ok; Hur, Min; Song, Young-Hoon

    2013-10-01

    To activate a catalyst efficiently at low temperature by plasma for environmental control, we developed a hybrid reactor that combines plasma with a honeycomb-structured catalyst in a practical manner. The reactor developed generated stable cold plasma at atmospheric pressure because of the dielectric and conductive nature of the honeycomb catalyst by consuming low amounts of power. In this reactor, the applied voltage and temperature determined the balance between the oxidation and adsorption by the plasma and catalyst. The synergistic reaction of the plasma and catalyst was more effective at low temperatures, resulting in a reduction in a lowered light-off temperature. PMID:23991700

  7. Flow past an array of catalyst blocks with a honeycomb structure

    SciTech Connect

    Bespalov, A.V.

    1992-07-10

    There is interest in an organized stationary catalyst beds consisting of block catalysts with a honeycomb structure: The flow is directed between vertically positioned blocks, in which the through channels are oriented perpendicularly to the direction of the incident flow ({alpha} = 90{degrees}). Calculations of the flow past a single block of honey comb structure were performed for this case, and it has been shown that the surface of the through channel is accessible to the reaction flow. The authors continued this effort to quantitate the flow with honeycomb catalysts. 9 refs., 2 figs.

  8. Finite element analysis of effective mechanical properties, vibration and acoustic performance of auxetic chiral core sandwich structures

    NASA Astrophysics Data System (ADS)

    Joshi, Hrishikesh Ravindra

    Honeycomb cellular materials are widely used in engineering applications due to their high strength to weight ratio and controllable effective mechanical properties. The effective properties are controlled by varying the geometry of the repetitive unit cells of honeycomb structure. Sandwich panels made of honeycomb cores are beneficial in many applications including vibration isolation and sound transmission reduction. Sandwich panels with standard honeycomb core configurations have previously been studied with regards to sound transmission behavior. It has been established that the auxetic honeycomb cores, having negative in-plane Poisson's ratio, exhibit higher sound transmission loss as compared to regular honeycomb cores. In this study, the vibration and sound transmission response of novel auxetic chiral honeycomb structures (both hexa-chiral and anti-tetra chiral), have been investigated in detail using finite element analysis with two-dimensional plane elasticity elements. Chiral honeycomb structures are made up of a linear tessellation of periodic unit cell, which consists of circular nodes of radius ' r ' connected to each other by tangent ligaments of length ' L '. The distance between two adjacent circular nodes is ' R '. These geometric parameters are tailored to obtain the chiral structure with desired effective mechanical properties of in-plane Poisson's ratio, Young's modulus and shear modulus. Results show that, for both the hexa-chiral and anti-tetra-chiral configurations with same thickness, structures with smaller node radius 'r' have higher in-plane negative Poisson's ratio, effective Young's modulus, and shear modulus. The Poisson's ratio of anti-tetra-chiral structure with small node radius and thickness is found to approach the limit of -1. A steady state dynamic response of the chiral honeycomb sandwich panel subjected to uniform pressure load on the bottom face-sheet is also investigated over a frequency range of 1 Hz to 2000 Hz. It is observed that, by changing the node radius of the chiral structures, the frequency range for the global sandwich structure bending resonances and local intra-cell core resonances can be shifted. Within the bandwidth controlled by the intra-cell core resonances we observe higher surface velocity vibration amplitude and decrease in sound transmission loss. For the structure with bigger node radius, the bending resonances and intra-cell resonance are shifted to lower frequencies as compared to the structure with smaller node radius. Finally, the sound transmission loss behavior of sandwich panels made of chiral honeycomb cores is investigated with plane pressure wave incident at normal as well as variable incidence angles. The results suggest that, in case of both the hexa-chiral and anti-tetra-chiral sandwich panels, the core structure with smallest node radius exhibits higher sound transmission loss as compared to the core structure with bigger node radius. Among all the different chiral honeycomb structures investigated in this study, the anti-tetra-chiral structure with smallest node radius exhibits the highest sound transmission loss. It is interesting to observe that this is also the structure with highest value of negative in-plane Poisson's ratio.

  9. Aluminum microstructures on anodic alumina for aluminum wiring boards.

    PubMed

    Jha, Himendra; Kikuchi, Tatsuya; Sakairi, Masatoshi; Takahashi, Hideaki

    2010-03-01

    The paper demonstrates simple methods for the fabrication of aluminum microstructures on the anodic oxide film of aluminum. The aluminum sheets were first engraved (patterned) either by laser beam or by embossing to form deep grooves on the surface. One side of the sheet was then anodized, blocking the other side by using polymer mask to form the anodic alumina. Because of the lower thickness at the bottom part of the grooves, the part was completely anodized before the complete oxidation of the other parts. Such selectively complete anodizing resulted in the patterns of metallic aluminum on anodic alumina. Using the technique, we fabricated microstructures such as line patterns and a simple wiring circuit-board-like structure on the anodic alumina. The aluminum microstructures fabricated by the techniques were embedded in anodic alumina/aluminum sheet, and this technique is promising for applications in electronic packaging and devices. PMID:20356280

  10. Nanocalculation: Aluminum Block Choose a piece of aluminum. Split up chores amongst your team members. You

    E-print Network

    Falvo, Michael

    Nanocalculation: Aluminum Block Choose a piece of aluminum. Split up chores amongst your team (diameter) are the Aluminum atoms? 3. If pounded your piece of aluminum into a single atom thick layer, how

  11. Aluminum Carbothermic Technology

    SciTech Connect

    Bruno, Marshall J.

    2005-03-31

    This report documents the non-proprietary research and development conducted on the Aluminum Carbothermic Technology (ACT) project from contract inception on July 01, 2000 to termination on December 31, 2004. The objectives of the program were to demonstrate the technical and economic feasibility of a new carbothermic process for producing commercial grade aluminum, designated as the ''Advanced Reactor Process'' (ARP). The scope of the program ranged from fundamental research through small scale laboratory experiments (65 kW power input) to larger scale test modules at up to 1600 kW power input. The tasks included work on four components of the process, Stages 1 and 2 of the reactor, vapor recovery and metal alloy decarbonization; development of computer models; and economic analyses of capital and operating costs. Justification for developing a new, carbothermic route to aluminum production is defined by the potential benefits in reduced energy, lower costs and more favorable environmental characteristics than the conventional Hall-Heroult process presently used by the industry. The estimated metrics for these advantages include energy rates at approximately 10 kWh/kg Al (versus over 13 kWh/kg Al for Hall-Heroult), capital costs as low as $1250 per MTY (versus 4,000 per MTY for Hall-Heroult), operating cost reductions of over 10%, and up to 37% reduction in CO2 emissions for fossil-fuel power plants. Realization of these benefits would be critical to sustaining the US aluminum industries position as a global leader in primary aluminum production. One very attractive incentive for ARP is its perceived ability to cost effectively produce metal over a range of smelter sizes, not feasible for Hall-Heroult plants which must be large, 240,000 TPY or more, to be economical. Lower capacity stand alone carbothermic smelters could be utilized to supply molten metal at fabrication facilities similar to the mini-mill concept employed by the steel industry. Major accomplishments for the program include definition of the system thermo-chemistry, demonstration of reactor stage 1, development of reactor stage 2 critical components in a 500 kW module, experimental determination of the vapor recovery reactor fundamentals, detailed design and installation of an advanced stage 1/vapor recovery reactor, feasibility of efficient separation of Al-C metal alloy product, updated capital and operating cost estimates, and development of computer models for all steps of the Advanced Reactor Process.

  12. Ferroquadrupolar phase of the bilinear-biquadratic Heisenberg model on the honeycomb lattice at zero temperature

    NASA Astrophysics Data System (ADS)

    Pires, A. S. T.

    2015-11-01

    Using the SU(3) Schwinger boson formalism, also named the flavor theory, I study the ferroquadrupolar phase of the bilinear-biquadratic Heisenberg model on the honeycomb lattice at zero temperature. The dispersion relations, the quadrupole moment and the static quadrupole structure factor are calculated.

  13. Properties of a chiral honeycomb with a Poisson's ratio -1 D. Prall, R. S. Lakes

    E-print Network

    Lakes, Roderic

    for technological use. However, improved manufacturing processes have made these unique composite materials more in a variety of engineering applications. In particular, honeycomb cell structures are very prevalent. The continuing desire for stronger, lighter weight, structural materials for use in aerospace and aircraft

  14. Evaluation of the in-service performance behavior of honeycomb composite sandwich structures

    SciTech Connect

    Shafizadeh, J.E.; Seferis, J.C.; Chesmar, E.F.; Geyer, R.

    1999-12-01

    When honeycomb composite structures are fabricated for the aerospace industry, they are designed to be closed to their operating environment for the life of the composite structure. However, once in service, this design can break down. Damage can set in motion a chain reaction of events that will ultimately degrade the mechanical integrity of the composite structure. Through thermographic analysis, the tendency of honeycomb composite structures to absorb and retain water was investigated, and an attempt was made to quantify the extent of water ingression in the Boeing 767 aircraft. Through thermographic analysis, the exterior honeycomb composite structures were found to contain less than 50 kg of water per plane. On average, over 90% of the water found on an aircraft was contained in five problematic parts, which included the outboard flap wedge, the nose landing gear doors, the main landing gear doors, the fixed upper wing panels, and the escape slide door. Kevlar lamina induced microcracking, skin porosity problems, and cracked potting compound were the root causes of water ingression and migration in these structures. Ultimately, this research will aid in the fundamental understanding and design of future honeycomb composite sandwich structures.

  15. International Journal of Impact Engineering 35 (2008) 10631074 Mechanical response of metallic honeycomb sandwich panel structures

    E-print Network

    Hutchinson, John W.

    2008-01-01

    honeycomb sandwich panel structures to high-intensity dynamic loading Kumar P. Dharmasenaa,Ã, Haydn N sandwich panels made from a super-austenitic stainless steel alloy. Tests were conducted at three levels of impulse load on the sandwich panels and solid plates with the same areal density. Impulse was varied

  16. Effective elastic and transport properties of regular honeycombs for all densities

    E-print Network

    Torquato, Salvatore

    Effective elastic and transport properties of regular honeycombs for all densities S. Hyun and S that lie between these extreme limits. The purpose of this paper is to quantify the effective elastic Jersey 08544 (Received 3 February 2000; accepted 21 June 2000) The effective planar elastic moduli

  17. Relationship Between Honeycombing and Collagen Breakdown in Skipjack Tuna, Katsuwonus pelamis

    E-print Network

    , a spoilage condition that affects the connective tissue of tuna, appears after the fish have been given a low surface. In extreme cases the connective tissue appears vac- uolated and resembles a vacant hon- eycomb-Honeycombing, a condi- tion that affects the connective tissue, was studied in skipjack tuna under controlled conditions

  18. Study made to control depth of potting compound for honeycomb sandwich fasteners

    NASA Technical Reports Server (NTRS)

    Cushman, J.

    1966-01-01

    Study determines optimum fastener insert size and shape, type of embedding cement, diameter, undercut and depth control by fiber glass plug in a honeycomb structure for maximum tensile strength The best potting compound is 5-5-1 weight mixture of epoxy resin, curing agent, and milled glass fibers.

  19. Shearography for Non-destructive Inspection with applications to BAT Mask Tile Adhesive Bonding and Specular Surface Honeycomb Panels

    NASA Technical Reports Server (NTRS)

    Lysak, Daniel B.

    2003-01-01

    The applicability of shearography techniques for non-destructive evaluation in two unique application areas is examined. In the first application, shearography is used to evaluate the quality of adhesive bonds holding lead tiles to the B.4T gamma ray mask for the NASA Swift program. Using a vibration excitation, the more poorly bonded tiles are readily identifiable in the shearography image. A quantitative analysis is presented that compares the shearography results with a destructive pull test measuring the force at bond failure. The second application is to evaluate the bonding between the skin and core of a honeycomb structure with a specular (mirror-like) surface. In standard shearography techniques, the object under test must have a diffuse surface to generate the speckle patterns in laser light, which are then sheared. A novel configuration using the specular surface as a mirror to image speckles from a diffuser is presented, opening up the use of shearography to a new class of objects that could not have been examined with the traditional approach. This new technique readily identifies large scale bond failures in the panel, demonstrating the validity of this approach.

  20. Mineral of the month: aluminum

    USGS Publications Warehouse

    Plunkert, Patricia A.

    2005-01-01

    Aluminum is the second most abundant metallic element in Earth’s crust after silicon. Even so, it is a comparatively new industrial metal that has been produced in commercial quantities for little more than 100 years. Aluminum is lightweight, ductile, malleable and corrosion resistant, and is a good conductor of heat and electricity. Weighing about one-third as much as steel or copper per unit of volume, aluminum is used more than any other metal except iron. Aluminum can be fabricated into desired forms and shapes by every major metalworking technique to add to its versatility.

  1. Laser welding of aluminum alloys

    SciTech Connect

    Leong, K.H.; Sabo, K.R.; Sanders, P.G.; Spawr, W.J.

    1997-03-01

    Recent interest in reducing the weight of automobiles to increase fuel mileage has focused attention on the use of aluminum and associated joining technologies. Laser beam welding is one of the more promising methods for high speed welding of aluminum. Consequently, substantial effort has been expended in attempting to develop a robust laser beam welding process. Early results have not been very consistent in the process requirements but more definitive data has been produced recently. This paper reviews the process parameters needed to obtain consistent laser welds on 5,000 series aluminum alloys and discusses the research necessary to make laser processing of aluminum a reality for automotive applications.

  2. Nanostructured 2D Diporphyrin Honeycomb Film: Photoelectrochemistry, Photodegradation, and Antibacterial Activity.

    PubMed

    Zhao, Yuewu; Shang, Qiuwei; Yu, Jiachao; Zhang, Yuanjian; Liu, Songqin

    2015-06-10

    Surface patterns of well-defined nanostructures play important roles in fabrication of optoelectronic devices and applications in catalysis and biology. In this paper, the diporphyrin honeycomb film, composed of titanium dioxide, protoporphyrin IX, and hemin (TiO2/PPIX/Hem), was synthesized using a dewetting technique with the well-defined polystyrene (PS) monolayer as a template. The TiO2/PPIX/Hem honeycomb film exhibited a higher photoelectrochemical response than that of TiO2 or TiO2/PPIX, which implied a high photoelectric conversion efficiency and a synergistic effect between the two kinds of porphyrins. The TiO2/PPIX/Hem honeycomb film was also a good photosensitizer due to its ability to generate singlet oxygen ((1)O2) under irradiation by visible light. This led to the use of diporphyrin TiO2/PPIX/Hem honeycomb film for the photocatalytic inactivation of bacteria. In addition, the photocatalytic activities of other metal-diporphyrin-based honeycomb films, such as TiO2/MnPPIX/Hem, TiO2/CoPPIX/Hem, TiO2/NiPPIX/Hem, TiO2/CuPPIX/Hem, and TiO2/ZnPPIX/Hem, were investigated. The result demonstrated that the photoelectric properties of diporphyrin-based film could be effectively enhanced by further coupling of porphyrin with metal ions. Such enhanced performance of diporphyrin compounds opened a new way for potential applications in various photoelectrochemical devices and medical fields. PMID:25992484

  3. Towards a better understanding of honeycomb alternating magnetic networks.

    PubMed

    Marino, Nadia; Armentano, Donatella; De Munno, Giovanni; Lloret, Francesc; Cano, Joan; Julve, Miguel

    2015-06-28

    Two new two-dimensional homometallic compounds {[M2(bpm)(ox)2]n·5nH2O} with M = Co(II) (1) and Zn(II) (2) and the mononuclear nickel(II) complex [Ni(bpm)2(ox)]·2H2O (3) [bpm = 2,2'-bipyrimidine and ox = oxalate] have been prepared and structurally characterized. 1 and 2 are isostructural compounds whose structures are made up of oxalate-bridged M(II) cations cross-linked by bis-bidentate bpm molecules to afford a honeycomb layered network extending in the crystallographic ab plane. The layers are eclipsed along the crystallographic c axis and show graphitic-like interactions between the bpm rings. The three-dimensional supramolecular network deriving from such interactions is characterized by hexagonal-shaped channels extending in the same direction. Each M(II) ion in 1 and 2 is tris-chelated with four oxygen atoms from two oxalate groups and two bpm-nitrogen atoms building a distorted octahedral surrounding. The reduced values of the angles subtended by the bis-chelating bpm [77.69(8) (1) and 76.59(8)° (2)] and oxalate [79.69(6) (1) and 80.01(5)° (2)] are the main factors accounting for this distortion. The values of the metal-metal separation through bridging bpm are 5.6956(7) (1) and 5.7572(9) Å (2), whereas those across the bis-bidentate oxalate are 5.4306(4) (1) and 5.4058(5) Å (2). 3 is a neutral mononuclear nickel(II) complex where each metal ion is six-coordinate with four nitrogen atoms from two bpm ligands in a cis arrangement and two oxalate-oxygen atoms building a somewhat distorted octahedral surrounding. The values of the angles subtended at the nickel(II) ion by bpm and oxalate are 78.14(4) and 80.95(5)°, respectively. The magnetic properties of 1 have been investigated in the temperature range 1.9-295 K. They are typical of an overall antiferromagnetic coupling with a maximum of the magnetic susceptibility at 22.0 K. The analysis of the susceptibility data of 1 through an effective spin Hamiltonian allowed a satisfactory simulation in the temperature range 10-295 K with the best-fit parameters ? = -110 cm(-1), ? = 1.1, |?| = 400 cm(-1), J(ox) = -11.1 cm(-1) and J(bpm) = -5.0 cm(-1). The values of the antiferromagnetic coupling through bpm and ox in 1 have also been supported by electronic structure calculations based on Density Functional Theory (DFT) and they compare well with those reported in the literature for bpm-bridged dicobalt(II) complexes and oxalate-bridged cobalt(II) chains. PMID:25994291

  4. Production of aluminum metal by electrolysis of aluminum sulfide

    DOEpatents

    Minh, N.Q.; Loutfy, R.O.; Yao, N.P.

    1982-04-01

    Metallic aluminum may be produced by the electrolysis of Al/sub 2/S/sub 3/ at 700 to 800/sup 0/C in a chloride melt composed of one or more alkali metal chlorides, and one or more alkaline earth metal chlorides and/or aluminum chloride to provide improved operating characteristics of the process.

  5. Production of aluminum metal by electrolysis of aluminum sulfide

    DOEpatents

    Minh, Nguyen Q. (Woodridge, IL); Loutfy, Raouf O. (Tucson, AZ); Yao, Neng-Ping (Clarendon Hills, IL)

    1984-01-01

    Production of metallic aluminum by the electrolysis of Al.sub.2 S.sub.3 at 700.degree.-800.degree. C. in a chloride melt composed of one or more alkali metal chlorides, and one or more alkaline earth metal chlorides and/or aluminum chloride to provide improved operating characteristics of the process.

  6. Selective Adsorption of Sodium Aluminum Fluoride Salts from Molten Aluminum

    SciTech Connect

    Leonard S. Aubrey; Christine A. Boyle; Eddie M. Williams; David H. DeYoung; Dawid D. Smith; Feng Chi

    2007-08-16

    Aluminum is produced in electrolytic reduction cells where alumina feedstock is dissolved in molten cryolite (sodium aluminum fluoride) along with aluminum and calcium fluorides. The dissolved alumina is then reduced by electrolysis and the molten aluminum separates to the bottom of the cell. The reduction cell is periodically tapped to remove the molten aluminum. During the tapping process, some of the molten electrolyte (commonly referred as “bath” in the aluminum industry) is carried over with the molten aluminum and into the transfer crucible. The carryover of molten bath into the holding furnace can create significant operational problems in aluminum cast houses. Bath carryover can result in several problems. The most troublesome problem is sodium and calcium pickup in magnesium-bearing alloys. Magnesium alloying additions can result in Mg-Na and Mg-Ca exchange reactions with the molten bath, which results in the undesirable pickup of elemental sodium and calcium. This final report presents the findings of a project to evaluate removal of molten bath using a new and novel micro-porous filter media. The theory of selective adsorption or removal is based on interfacial surface energy differences of molten aluminum and bath on the micro-porous filter structure. This report describes the theory of the selective adsorption-filtration process, the development of suitable micro-porous filter media, and the operational results obtained with a micro-porous bed filtration system. The micro-porous filter media was found to very effectively remove molten sodium aluminum fluoride bath by the selective adsorption-filtration mechanism.

  7. Shearography for Non-Destructive Evaluation with Applications to BAT Mask Tile Adhesive Bonding and Specular Surface Honeycomb Panels

    NASA Technical Reports Server (NTRS)

    Lysak, Daniel B.

    2003-01-01

    In this report we examine the applicability of shearography techniques for nondestructive inspection and evaluation in two unique application areas. In the first application, shearography is used to evaluate the quality of adhesive bonds holding lead tiles to the BAT gamma ray mask for the NASA Swift program. By exciting the mask with a vibration, the more poorly bonded tiles can be distinguished by their greater displacement response, which is readily identifiable in the shearography image. A quantitative analysis is presented that compares the shearography results with a destructive pull test measuring the force at bond failure. Generally speaking, the results show good agreement. Further investigation would be useful to optimize certain test parameters such as vibration frequency and amplitude. The second application is to evaluate the bonding between the skin and core of a honeycomb structure with a specular (mirror-like) surface. In standard shearography techniques, the object under test must have a diffuse surface to generate the speckle patterns in laser light, which are then sheared. A novel configuration using the specular surface as a mirror to image speckles from a diffuser is presented, opening up the use of shearography to a new class of objects that could not have been examined with the traditional approach. This new technique readily identifies large scale bond failures in the panel, demonstrating the validity of this approach. For the particular panel examined here, some scaling issues should be examined further to resolve the measurement scale down to the very small size of the core cells. In addition, further development should be undertaken to determine the general applicability of the new approach and to establish a firm quantitative foundation.

  8. Aluminum vehicle breaks new ground

    SciTech Connect

    Ashley, S.

    1994-02-01

    This article examines the efforts of automobile manufacturers and aluminum producers to develop a light weight crash resistant automobile. The topics of the article include alloys used, production techniques, fastening and bonding techniques, rigidity and crush resistance, weight reduction, die-casting and extruding of aluminum, design and construction of space frame.

  9. The Benefits of Aluminum Windows.

    ERIC Educational Resources Information Center

    Goyal, R. C.

    2002-01-01

    Discusses benefits of aluminum windows for college construction and renovation projects, including that aluminum is the most successfully recycled material, that it meets architectural glass deflection standards, that it has positive thermal energy performance, and that it is a preferred exterior surface. (EV)

  10. Aluminum Nanoholes for Optical Biosensing.

    PubMed

    Barrios, Carlos Angulo; Canalejas-Tejero, Víctor; Herranz, Sonia; Urraca, Javier; Moreno-Bondi, María Cruz; Avella-Oliver, Miquel; Maquieira, Ángel; Puchades, Rosa

    2015-01-01

    Sub-wavelength diameter holes in thin metal layers can exhibit remarkable optical features that make them highly suitable for (bio)sensing applications. Either as efficient light scattering centers for surface plasmon excitation or metal-clad optical waveguides, they are able to form strongly localized optical fields that can effectively interact with biomolecules and/or nanoparticles on the nanoscale. As the metal of choice, aluminum exhibits good optical and electrical properties, is easy to manufacture and process and, unlike gold and silver, its low cost makes it very promising for commercial applications. However, aluminum has been scarcely used for biosensing purposes due to corrosion and pitting issues. In this short review, we show our recent achievements on aluminum nanohole platforms for (bio)sensing. These include a method to circumvent aluminum degradation--which has been successfully applied to the demonstration of aluminum nanohole array (NHA) immunosensors based on both, glass and polycarbonate compact discs supports--the use of aluminum nanoholes operating as optical waveguides for synthesizing submicron-sized molecularly imprinted polymers by local photopolymerization, and a technique for fabricating transferable aluminum NHAs onto flexible pressure-sensitive adhesive tapes, which could facilitate the development of a wearable technology based on aluminum NHAs. PMID:26184330

  11. Primary Aluminum Plants Worldwide - 1998

    USGS Publications Warehouse

    1999-01-01

    The 1990 U.S. Bureau of Mines publication, Primary Aluminum Plants Worldwide, has been updated and is now available. The 1998 USGS edition of Primary Aluminum Plants Worldwide is published in two parts. Part I—Detail contains information on individual primary smelter capacity, location, ownership, sources of energy, and other miscellaneous information. Part II—Summary summarizes the capacity data by country

  12. Lost-Soap Aluminum Casting.

    ERIC Educational Resources Information Center

    Mihalow, Paula

    1980-01-01

    Lost-wax casting in sterling silver is a costly experience for the average high school student. However, this jewelry process can be learned at no cost if scrap aluminum is used instead of silver, and soap bars are used instead of wax. This lost-soap aluminum casting process is described. (Author/KC)

  13. Aluminum Nanoholes for Optical Biosensing

    PubMed Central

    Barrios, Carlos Angulo; Canalejas-Tejero, Víctor; Herranz, Sonia; Urraca, Javier; Moreno-Bondi, María Cruz; Avella-Oliver, Miquel; Maquieira, Ángel; Puchades, Rosa

    2015-01-01

    Sub-wavelength diameter holes in thin metal layers can exhibit remarkable optical features that make them highly suitable for (bio)sensing applications. Either as efficient light scattering centers for surface plasmon excitation or metal-clad optical waveguides, they are able to form strongly localized optical fields that can effectively interact with biomolecules and/or nanoparticles on the nanoscale. As the metal of choice, aluminum exhibits good optical and electrical properties, is easy to manufacture and process and, unlike gold and silver, its low cost makes it very promising for commercial applications. However, aluminum has been scarcely used for biosensing purposes due to corrosion and pitting issues. In this short review, we show our recent achievements on aluminum nanohole platforms for (bio)sensing. These include a method to circumvent aluminum degradation—which has been successfully applied to the demonstration of aluminum nanohole array (NHA) immunosensors based on both, glass and polycarbonate compact discs supports—the use of aluminum nanoholes operating as optical waveguides for synthesizing submicron-sized molecularly imprinted polymers by local photopolymerization, and a technique for fabricating transferable aluminum NHAs onto flexible pressure-sensitive adhesive tapes, which could facilitate the development of a wearable technology based on aluminum NHAs. PMID:26184330

  14. The aluminum spot weld

    SciTech Connect

    Thornton, P.H.; Krause, A.R.; Davies, R.G.

    1996-03-01

    Weld conditions which promote long tip life for aluminum spot welds are not necessarily associated with high weld quality in terms of freedom from defects such as porosity, cracks and expulsion. Schedules which produce good weld nuggets in terms of the peel test and long tip life may not produce a good response in terms of fatigue life. The fatigue life range is optimized by maximizing the weld nugget diameter, i.e., by employing a weld schedule which may lead to expulsion and weld porosity. Weld strength, in both peel and overlap shear configurations, was found to be linearly dependent upon weld diameter. In the peel test, the strength was also dependent upon the base metal thickness, in that for a given thickness, there is a critical diameter for the transition between weld fracture and nugget pull-out. For a given nugget diameter, if pull-out is observed then the strength is greater than if fracture occurs through the weld. In the shear test, the opposite response was observed, the strength for nugget pull-out being less than that for weld shear failure. Weld pull-out was found only for the thinnest base metal thickness tested and the shear load depended only upon the weld diameter over the range of thicknesses tested. Maximum strength in an aluminum spot weld is obtained by maximizing the weld nugget diameter for that thickness of material.

  15. Recovering aluminum via plasma processing

    NASA Astrophysics Data System (ADS)

    Szente, R. N.; Schroeter, R. A.; Garcia, M. G.; Bender, O. W.

    1997-11-01

    A process based on the use of a plasma system for recovering aluminum from dross, beverage cans, and aluminum scrap has been developed. The plasma process is clean, and there is no need for the addition of any compound, such as salt. In principle, a higher recovery rate of aluminum is attainable, since no oxidation of the aluminum occurs during the process. An economic analysis shows that the operating costs for the plasma system are at least 23% cheaper than for the traditional process using air/gas or ail/oil burners; the plasma process also does not generate either of the common residues produced by the burners. The maintenance costs of the plasma process are also lower than that of the traditional process. Overall, the plasma system is cheaper, cleaner, and easier than the oil/gas burner technology when recovering aluminum from dross, beverage cans, and scrap.

  16. Buckling Testing and Analysis of Honeycomb Sandwich Panel Arc Segments of a Full-Scale Fairing Barrel Part 1: 8-Ply In-Autoclave Facesheets. Part 1; 8-Ply In-Autoclave Facesheets

    NASA Technical Reports Server (NTRS)

    Myers, David E.; Pineda, Evan J.; Zalewski, Bart F.; Kosareo, Daniel N.; Kellas, Sotiris

    2013-01-01

    Four honeycomb sandwich panels, representing 1/16th arc segments of a 10-m diameter barrel section of the heavy lift launch vehicle, were manufactured under the NASA Composites for Exploration program and the NASA Space Launch Systems program. Two configurations were chosen for the panels: 6-ply facesheets with 1.125 in. honeycomb core and 8-ply facesheets with 1.000 in. honeycomb core. Additionally, two separate carbon fiber/epoxy material systems were chosen for the facesheets: inautoclave IM7/977-3 and out-of-autoclave T40-800b/5320-1. Smaller 3.00- by 5.00-ft panels were cut from the 1/16th barrel sections. These panels were tested under compressive loading at the NASA Langley Research Center. Furthermore, linear eigenvalue and geometrically nonlinear finite element analysis was performed to predict the compressive response of the 3.00- by 5.00-ft panels. This manuscript summarizes the experimental and analytical modeling efforts pertaining to the panel composed of 8-ply, IM7/977-3 facesheets (referred to Panel A). To improve the robustness of the geometrically nonlinear finite element model, measured surface imperfections were included in the geometry of the model. Both the linear and nonlinear models yield good qualitative and quantitative predictions. Additionally, it was predicted correctly that the panel would fail in buckling prior to failing in strength. Furthermore, several imperfection studies were performed to investigate the influence of geometric imperfections, fiber misalignments, and three-dimensional (3 D) effects on the compressive response of the panel.

  17. New honeycomb iridium(v) oxides: NaIrO3 and Sr3CaIr2O9.

    PubMed

    Wallace, David C; McQueen, Tyrel M

    2015-12-21

    We report the structures and physical properties of two new iridates, NaIrO3 and Sr3CaIr2O9, both of which contain continuous two-dimensional honeycomb connectivity. NaIrO3 is produced by room temperature oxidative deintercalation of sodium from Na2IrO3, and contains edge-sharing IrO6 octahedra that form a planar honeycomb lattice. Sr3CaIr2O9, produced via conventional solid-state synthesis, hosts a buckled honeycomb lattice with novel corner-sharing connectivity between IrO6 octahedra. Both of these new compounds are comprised of Ir(5+) (5d(4)) and exhibit negligible magnetic susceptibility. They are thus platforms to investigate the origin of the nonmagnetic behavior exhibited by Ir(5+) oxides, and provide the first examples of a J = 0 state on a honeycomb lattice. PMID:26505461

  18. Development of Composite Honeycomb and Solid Laminate Reference Standards to Aid Aircraft Inspections

    SciTech Connect

    Dorrell, L.; Roach, D.

    1999-03-04

    The rapidly increasing use of composites on commercial airplanes coupled with the potential for economic savings associated with their use in aircraft structures means that the demand for composite materials technology will continue to increase. Inspecting these composite structures is a critical element in assuring their continued airworthiness. The FAA's Airworthiness Assurance NDI Validation Center, in conjunction with the Commercial Aircraft Composite Repair Committee (CACRC), is developing a set of composite reference standards to be used in NDT equipment calibration for accomplishment of damage assessment and post-repair inspection of all commercial aircraft composites. In this program, a series of NDI tests on a matrix of composite aircraft structures and prototype reference standards were completed in order to minimize the number of standards needed to carry out composite inspections on aircraft. Two tasks, related to composite laminates and non-metallic composite honeycomb configurations, were addressed. A suite of 64 honeycomb panels, representing the bounding conditions of honeycomb construction on aircraft, were inspected using a wide array of NDI techniques. An analysis of the resulting data determined the variables that play a key role in setting up NDT equipment. This has resulted in a prototype set of minimum honeycomb reference standards that include these key variables. A sequence of subsequent tests determined that this minimum honeycomb reference standard set is able to fully support inspections over the fill range of honeycomb construction scenarios. Current tasks are aimed at optimizing the methods used to engineer realistic flaws into the specimens. In the solid composite laminate arena, we have identified what appears to be an excellent candidate, G11 Phenolic, as a generic solid laminate reference standard material. Testing to date has determined matches in key velocity and acoustic impedance properties, as well as, low attenuation relative to carbon laminates. Furthermore, comparisons of resonance testing response curves from the G11 Phenolic prototype standard was very similar to the resonance response curves measured on the existing carbon and fiberglass laminates. NDI data shows that this material should work for both pulse-echo (velocity-based) and resonance (acoustic impedance-based) inspections. Additional testing and industry review activities are underway to complete the validation of this material.

  19. Casting the first 8.4-m borosilicate honeycomb mirror for the Large Binocular Telescope

    NASA Astrophysics Data System (ADS)

    Hill, John M.; Angel, J. Roger P.; Lutz, Randall D.; Olbert, Blain H.; Strittmatter, Peter A.

    1998-08-01

    We report on the casting of the first 8.4 meter diameter borosilicate honeycomb mirror at the Steward Observatory Mirror Laboratory. This blank will become the world's largest monolithic glass telescope mirror, and is the first of two mirrors for the large Binocular Telescope Project. The honeycomb 8.4 meter mirror was cast from 21 tons of E6 borosilicate glass manufactured by Ohara. This glass is melted into a mold constructed of aluminosilicate fiber to produce a honeycomb structure with roughly 20% of solid density. The 1662 hexagonal voids that form the honeycomb structure are produced by ceramic fiber boxes bolted to the bottom of the mold with SiC bolts. The furnace rotates at 6.8 rpm during the casting process to produce the F/1.14 paraboloid on the front surface. This shaping minimizes the amount of glass which must be removed during the grinding process. The front faceplate of the mirror will be 28 mm thick after generating and the back faceplate will be 25 mm. The overall thickness of the finished honeycomb blank is 89 cm at the outer edge and 44 cm at the central hole. The first 8.4 meter mirror blank was cast in January 1997. During the casting, two tons of glass leaked from the mold inside the spinning furnace. After a three month annealing cycle the furnace was opened for inspection. As a result of the leakage about 2 square meters of the faceplate near one edge of the mirror was too thin to be polished. In April 1997, an additional two tons of glass was loaded on top of the intact honeycomb structure. In June 1997, after heating slowly back to the annealing temperature, this extra glass was flash melted onto the front of the blank to assure that the faceplate was of sufficient thickness. After a further three month annealing cycle, the furnace was re-opened to reveal a superb casting with low bubble content and little trace of the fusion boundary. The blank has been removed from the furnace using a fixture glued to the upper surface of the blank. It will soon be stripped of its mold material in preparation for polishing.

  20. Choice of optimal properties of molding compounds for extrusion of block supports and catalysts with the honeycomb structure

    SciTech Connect

    Prokof`ev, V.Yu.; Il`in, A.P.; Shirokov, Yu.G.; Yurchenko, E.N.

    1995-09-20

    Properties of compounds for molding of block supports and catalysts with the honeycomb structure have been studied. The examples studied include ultraporcelain, alumina, titanium dioxide, clays, and graphite. The molding properties of these compounds are characterized by such parameters as the relationship between deformations, relaxation time, power for destruction of the coagulation structure, and flow index. For molding of blocks with the honeycomb structure compounds with enhanced plastic properties and a stable coagulation structure are suggested.

  1. 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.

  2. Use of Aluminum in Air-Brazing Aluminum Oxide

    SciTech Connect

    Kim, Jin Yong Y.; Hardy, John S.; Weil, K. Scott

    2004-06-01

    A commercial aluminum foil was used to braze alumina plates in air. Although the outer surface of the aluminum oxidizes in air, the majority of the aluminum underneath remains unoxidized during brazing, allowing the ceramic pieces to be joined together with adequate strength. In fact, the joint exhibits a modest increase in bend strength when exposed to air at 850ºC for a prolonged period of time. Joint strength testing and subsequent examination of the fracture surfaces of the joints indicate that the joints are inherently ductile, even after long-term, high-temperature air exposure.

  3. Aluminum Zintl anion moieties within sodium aluminum clusters

    SciTech Connect

    Wang, Haopeng; Zhang, Xinxing; Ko, Yeon Jae; Grubisic, Andrej; Li, Xiang; Ganteför, Gerd; Bowen, Kit H. E-mail: kiran@mcneese.edu; Schnöckel, Hansgeorg; Eichhorn, Bryan W.; Lee, Mal-Soon; Jena, P.; Kandalam, Anil K. E-mail: kiran@mcneese.edu; Kiran, Boggavarapu E-mail: kiran@mcneese.edu

    2014-02-07

    Through a synergetic combination of anion photoelectron spectroscopy and density functional theory based calculations, we have established that aluminum moieties within selected sodium-aluminum clusters are Zintl anions. Sodium–aluminum cluster anions, Na{sub m}Al{sub n}{sup ?}, were generated in a pulsed arc discharge source. After mass selection, their photoelectron spectra were measured by a magnetic bottle, electron energy analyzer. Calculations on a select sub-set of stoichiometries provided geometric structures and full charge analyses for both cluster anions and their neutral cluster counterparts, as well as photodetachment transition energies (stick spectra), and fragment molecular orbital based correlation diagrams.

  4. Aluminum anode for aluminum-air battery - Part I: Influence of aluminum purity

    NASA Astrophysics Data System (ADS)

    Cho, Young-Joo; Park, In-Jun; Lee, Hyeok-Jae; Kim, Jung-Gu

    2015-03-01

    2N5 commercial grade aluminum (99.5% purity) leads to the lower aluminum-air battery performances than 4N high pure grade aluminum (99.99% purity) due to impurities itself and formed impurity complex layer which contained Fe, Si, Cu and others. The impurity complex layer of 2N5 grade Al declines the battery voltage on standby status. It also depletes discharge current and battery efficiency at 1.0 V which is general operating voltage of aluminum-air battery. However, the impurity complex layer of 2N5 grade Al is dissolved with decreasing discharge voltage to 0.8 V. This phenomenon leads to improvement of discharge current density and battery efficiency by reducing self-corrosion reaction. This study demonstrates the possibility of use of 2N5 grade Al which is cheaper than 4N grade Al as the anode for aluminum-air battery.

  5. Aluminum plasmonic photocatalysis.

    PubMed

    Hao, Qi; Wang, Chenxi; Huang, Hao; Li, Wan; Du, Deyang; Han, Di; Qiu, Teng; Chu, Paul K

    2015-01-01

    The effectiveness of photocatalytic processes is dictated largely by plasmonic materials with the capability to enhance light absorption as well as the energy conversion efficiency. Herein, we demonstrate how to improve the plasmonic photocatalytic properties of TiO2/Al nano-void arrays by overlapping the localized surface plasmon resonance (LSPR) modes with the TiO2 band gap. The plasmonic TiO2/Al arrays exhibit superior photocatalytic activity boasting an enhancement of 7.2 folds. The underlying mechanisms concerning the radiative energy transfer and interface energy transfer processes are discussed. Both processes occur at the TiO2/Al interface and their contributions to photocatalysis are evaluated. The results are important to the optimization of aluminum plasmonic materials in photocatalytic applications. PMID:26497411

  6. Aluminum plasmonic photocatalysis

    PubMed Central

    Hao, Qi; Wang, Chenxi; Huang, Hao; Li, Wan; Du, Deyang; Han, Di; Qiu, Teng; Chu, Paul K.

    2015-01-01

    The effectiveness of photocatalytic processes is dictated largely by plasmonic materials with the capability to enhance light absorption as well as the energy conversion efficiency. Herein, we demonstrate how to improve the plasmonic photocatalytic properties of TiO2/Al nano-void arrays by overlapping the localized surface plasmon resonance (LSPR) modes with the TiO2 band gap. The plasmonic TiO2/Al arrays exhibit superior photocatalytic activity boasting an enhancement of 7.2 folds. The underlying mechanisms concerning the radiative energy transfer and interface energy transfer processes are discussed. Both processes occur at the TiO2/Al interface and their contributions to photocatalysis are evaluated. The results are important to the optimization of aluminum plasmonic materials in photocatalytic applications. PMID:26497411

  7. Spray Rolling Aluminum Strip

    SciTech Connect

    Lavernia, E.J.; Delplanque, J-P; McHugh, K.M.

    2006-05-10

    Spray forming is a competitive low-cost alternative to ingot metallurgy for manufacturing ferrous and non-ferrous alloy shapes. It produces materials with a reduced number of processing steps, while maintaining materials properties, with the possibility of near-net-shape manufacturing. However, there are several hurdles to large-scale commercial adoption of spray forming: 1) ensuring strip is consistently flat, 2) eliminating porosity, particularly at the deposit/substrate interface, and 3) improving material yield. Through this program, a new strip/sheet casting process, termed spray rolling, has been developed, which is an innovative manufacturing technique to produce aluminum net-shape products. Spray rolling combines the benefits of twin-roll casting and conventional spray forming, showing a promising potential to overcome the above hurdles associated with spray forming. Spray rolling requires less energy and generates less scrap than conventional processes and, consequently, enables the development of materials with lower environmental impacts in both processing and final products. Spray Rolling was developed as a collaborative project between the University of California-Davis, the Colorado School of Mines, the Idaho National Engineering and Environmental Laboratory, and an industry team. The following objectives of this project were achieved: (1) Demonstration of the feasibility of the spray rolling process at the bench-scale level and evaluation of the materials properties of spray rolled aluminum strip alloys; and (2) Demonstration of 2X scalability of the process and documentation of technical hurdles to further scale up and initiate technology transfer to industry for eventual commercialization of the process.

  8. Aluminum toxicity. Hematological effects.

    PubMed

    Mahieu, S; del Carmen Contini, M; Gonzalez, M; Millen, N; Elias, M M

    2000-01-01

    Sequential effects of intoxication with aluminum hydroxide (Al) (80 mg/Kg body weight, i.p., three times a week), were studied on rats from weaning and up to 28 weeks. The study was carried out on hematological and iron metabolism-related parameters on peripheral blood, at the end of the 1st, 2nd, 3rd, 4th, 5th and 6th months of exposure. As it was described that hematotoxic effects of Al are mainly seen together with high levels of uremia, renal function was measured at the same periods. The animals treated developed a microcytosis and was accompanied by a decrease in mean corpuscular hemoglobin (MCH). Significantly lower red blood cell counts (RBC million/microl) were found in rats treated during the 1st month. These values matched those obtained for control rats during the 2nd month. From the 3rd month onwards, a significant increase was observed as compared to control groups, and the following values were obtained by the 6th month: (T) 10.0 +/- 0.3 versus (C) 8.7 +/- 0.2 (million/microl). Both MCH and mean corpuscular volume (MCV) were found to be significantly lower in groups treated from the 2nd month. At the end of the 6th month the following values were found: MCH (T) 13.3 +/- 0.1 versus (C) 16.9 +/- 0.3 (pg); MCV (T) 42.1 +/- 0.7 versus (C) 51.8 +/- 0.9 (fl). Al was found responsible for lower serum iron concentration levels and in the percentage of transferrin saturation. Thus, although microcytic anemia constitutes an evidence of chronic aluminum exposure, prolonged exposure could lead to a recovery of hematocrit and hemoglobin concentration values with an increase in red cell number. Nevertheless, both microcytosis and the decrease of MCH would persist. These modifications took place without changes being observed in the renal function during the observation period. PMID:10643868

  9. Affleck-Kennedy-Lieb-Tasaki State on a Honeycomb Lattice from t2 g Orbitals

    NASA Astrophysics Data System (ADS)

    Koch-Janusz, Maciej; Khomskii, D. I.; Sela, Eran

    2015-06-01

    The two-dimensional Affeck-Kennedy-Lieb-Tasaki (AKLT) model on a honeycomb lattice has been shown to be a universal resource for quantum computation. In this valence bond solid, however, the spin interactions involve higher powers of the Heisenberg coupling (S?i.S?j)n, making these states seemingly unrealistic on bipartite lattices, where one expects a simple antiferromagnetic order. We show that those interactions can be generated by orbital physics in multiorbital Mott insulators. We focus on t2 g electrons on the honeycomb lattice and propose a physical realization of the spin-3 /2 AKLT state. We find a phase transition from the AKLT to the Néel state on increasing Hund's rule coupling, which is confirmed by density matrix renormalization group simulations. An experimental signature of the AKLT state consists of protected, free S =1 /2 spins on lattice vacancies, which may be detected in the spin susceptibility.

  10. Steps toward 8m honeycomb mirrors. VIII - Design and demonstration of a system of thermal control

    NASA Technical Reports Server (NTRS)

    Cheng, A. Y. S.; Angel, J. R. P.

    1986-01-01

    Directed jets of ambient temperature air are proposed for the maintenance of low internal temperature gradients and conformity with ambient temperatures in honeycomb-structure borosilicate glass telescope mirrors. The use of greater airflow on thicker sections, to match cooling rates, and the cooling or heating of the internal, back, and edge surfaces of the mirror at the same rate established by convection on the front surface, have been tested on a full scale glass thermal model of a single honeycomb cell from an 8-m diameter mirror. The internal thermal gradient (less than 0.1 C) and ambient-temperature-change lag (less than 0.24 C) ensure minimum image degradation.

  11. Friction-factor data for flat-plate tests of smooth and honeycomb surfaces

    NASA Technical Reports Server (NTRS)

    Ha, T. W.; Childs, Dara W.

    1992-01-01

    Friction factors for honeycomb surfaces were measured with a flat plate tester. The flat plate test apparatus was described and a method was discussed for determining the friction factor experimentally. The friction factor model was developed for the flat plate test based on the Fanno Line Flow. The comparisons of the friction factor were plotted for smooth surfaces and six-honeycomb surfaces with three-clearances, 6.9 bar to 17.9 bar range of inlet pressures, and 5,000 to 100,000 range of the Reynolds number. The optimum geometries for the maximum friction factor were found as a function of cell width to cell depth and cell width to clearance ratios.

  12. Friction factor data for flat plate tests of smooth and honeycomb surfaces. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Ha, Tae Woong

    1989-01-01

    Friction factors for honeycomb surfaces were measured with a flat plate tester. The flat plate test apparatus was described and a method was discussed for determining the friction factor experimentally. The friction factor model was developed for the flat plate test based on the Fanno Line Flow. The comparisons of the friction factor were plotted for smooth surfaces and six-honeycomb surfaces with three-clearances, 6.9 bar to 17.9 bar range of inlet pressures, and 5,000 to 100,000 range of the Reynolds number. The optimum geometries for the maximum friction factor were found as a function of cell width to cell depth and cell width to clearance ratios.

  13. Kitaev magnetism in honeycomb RuCl3 with intermediate spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Kim, Heung-Sik; Vijay Shankar, V.; Catuneanu, Andrei; Kee, Hae-Young

    2015-06-01

    Intensive studies of the interplay between spin-orbit coupling (SOC) and electronic correlations in transition-metal compounds have recently been undertaken. In particular, jeff=1 /2 bands on a honeycomb lattice provide a pathway to realize Kitaev's exactly solvable spin model. However, since current wisdom requires strong atomic SOC to make jeff=1 /2 bands, studies have been limited to iridium oxides. Contrary to this expectation, we demonstrate how Kitaev interactions arise in 4 d -orbital honeycomb ? -RuCl3 , despite having significantly weaker SOC than the iridium oxides, via assistance from electron correlations. A strong-coupling spin model for these correlation-assisted jeff=1 /2 bands is derived, in which large antiferromagnetic Kitaev interactions emerge along with ferromagnetic Heisenberg interactions. Our analyses suggest that the ground state is a zigzag-ordered phase lying close to the antiferromagnetic Kitaev spin liquid. Experimental implications for angle-resolved photoemission spectroscopy, neutron scattering, and optical conductivities are discussed.

  14. Electrical Control of Edge Magnetism in Two-Dimensional Buckled Honeycomb Lattice

    NASA Astrophysics Data System (ADS)

    Bao, Wei-Cheng; Zou, Liang-Jian

    2014-09-01

    We theoretically study indirect spin coupling strength between two magnetic impurities located on honeycomb Kane—Mele zigzag ribbon (KMZR) with periodic and open boundary (PB and OB). We show that spin interaction J in PB ribbons displays an AFM-FM oscillating behavior with increasing the staggered potential and electron density, and approaches to maximum at the edges. While the spin coupling in OB KMZR shows a trivial smooth AFM coupling with varying staggered potential. Such a novel J(?) behavior is the combining effect of finite size, topological edge states and inversion symmetry breaking induced by the staggered potential. We propose that one could control the edge magnetism electrically in two-dimensional buckled honeycomb materials, e.g., silicence, germanene and stanene.

  15. An alternative order-parameter for non-equilibrium generalized spin models on honeycomb lattices

    E-print Network

    Sastre, Francisco

    2015-01-01

    An alternative definition for the order-parameter is proposed, for a family of non-equilibrium spin models with up-down symmetry on honeycomb lattices, and which depends on two parameters. In contrast to the usual definition, our proposal takes into account that each site of the lattice can be associated with a local temperature which depends on the local environment of each site. Using the generalised voter motel as a test case, we analyse the phase diagram and the critical exponents in the stationary state and compare the results of the standard order-parameter with the ones following from our new proposal, on the honeycomb lattice. The stationary phase transition is in the Ising universality class. Finite-size corrections are also studied and the Wegner exponent is estimated as $\\omega=1.06(9)$.

  16. Insert facing tool. [manually operated cutting tool for forming studs in honeycomb material

    NASA Technical Reports Server (NTRS)

    Abernathy, W. J.; Snoddy, L. G. (inventors)

    1974-01-01

    A manually actuated tool for facing the exposed end of an insert installed in a honeycomb panel is described. Several cutting bits are held in a round body portion that is rotated around the end of a stud to provide the cutting action. Pressure is adjusted through a spring against the body portion and the surface of the stud by a pressure nut threaded on the stud. A diagram of the components of the device is provided.

  17. Preparation of Honeycomb SnO2 Foams and Configuration-Dependent Microwave Absorption Features.

    PubMed

    Zhao, Biao; Fan, Bingbing; Xu, Yawei; Shao, Gang; Wang, Xiaodong; Zhao, Wanyu; Zhang, Rui

    2015-12-01

    Ordered honeycomb-like SnO2 foams were successfully synthesized by means of a template method. The honeycomb SnO2 foams were analyzed by X-ray diffraction (XRD), thermogravimetric and differential scanning calorimetry (TG-DSC), laser Raman spectra, scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR). It can be found that the SnO2 foam configurations were determined by the size of polystyrene templates. The electromagnetic properties of ordered SnO2 foams were also investigated by a network analyzer. The results reveal that the microwave absorption properties of SnO2 foams were dependent on their configuration. The microwave absorption capabilities of SnO2 foams were increased by increasing the size of pores in the foam configuration. Furthermore, the electromagnetic wave absorption was also correlated with the pore contents in SnO2 foams. The large and high amounts pores can bring about more interfacial polarization and corresponding relaxation. Thus, the perfect ordered honeycomb-like SnO2 foams obtained in the existence of large amounts of 322 nm polystyrene spheres showed the outstanding electromagnetic wave absorption properties. The minimal reflection loss (RL) is -37.6 dB at 17.1 GHz, and RL less than -10 dB reaches 5.6 GHz (12.4-18.0 GHz) with thin thickness of 2.0 mm. The bandwidth (<-10 dB, 90% microwave dissipation) can be monitored in the frequency regime of 4.0-18.0 GHz with absorber thickness of 2.0-5.0 mm. The results indicate that these ordered honeycomb SnO2 foams show the superiorities of wide-band, high-efficiency absorption, multiple reflection and scatting, high antioxidation, lightweight, and thin thickness. PMID:26552325

  18. Buckling of regular, chiral and hierarchical honeycombs under a general macroscopic stress state

    PubMed Central

    Haghpanah, Babak; Papadopoulos, Jim; Mousanezhad, Davood; Nayeb-Hashemi, Hamid; Vaziri, Ashkan

    2014-01-01

    An approach to obtain analytical closed-form expressions for the macroscopic ‘buckling strength’ of various two-dimensional cellular structures is presented. The method is based on classical beam-column end-moment behaviour expressed in a matrix form. It is applied to sample honeycombs with square, triangular and hexagonal unit cells to determine their buckling strength under a general macroscopic in-plane stress state. The results were verified using finite-element Eigenvalue analysis. PMID:25002823

  19. Honeycomb-like graphitic ordered macroporous carbon prepared by pyrolysis of ammonium bicarbonate

    SciTech Connect

    Wang, Liancheng; Zhang, Junhao; School of Biology and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, Jiangsu 212003 ; Xu, Liqiang; Qian, Yitai

    2011-10-15

    Graphical abstract: Honeycomb-like graphitic macroporous carbon (HGMC) with big pores centered at 1-3 {mu}m, has been prepared by controlling the reaction temperature and amount of NH{sub 4}HCO{sub 3} at 550 {sup o}C in a sealed reaction system. Possible formation processes of HGMC are discussed on the experimental results. It is believed that the in situ formed MgO microparticles play a template role during the preparation of HGMC. Highlights: {yields} Honeycomb-like graphitic carbon was synthesized at 550 {sup o}C. {yields} The honeycomb-like graphitic carbon is macroposous structures. {yields} The formed MgO microparticles play a template role during the HGMC formation. {yields} The method can be expended to synthesize other porous or hollow carbon material. -- Abstract: Honeycomb-like graphitic macroporous carbon (HGMC) was synthesized by means of pyrolysis of NH{sub 4}HCO{sub 3} using Mg powder as reductant in an autoclave at 550 {sup o}C. The characterization of structure and morphology was carried out by X-ray diffraction (XRD), Raman spectrum, field-emission scanning electron microscopy (FESEM), and (High-resolution) transmission electron microscope [(HR)TEM]. The results of nitrogen adsorption-desorption indicate that the products are macropore materials with the pore size of 1-3 {mu}m, and the Brunauer-Emett-Teller (BET) surface area was 14 m{sup 2}/g. As a typical morphology, the possible growth process of HGMC was also investigated and discussed. The experimental results show that the in situ formed MgO microparticles play a template role during the HGMC formation.

  20. NASA-UVA Light Aerospace Alloy and Structure Technology Program Supplement: Aluminum-Based Materials for High Speed Aircraft

    NASA Technical Reports Server (NTRS)

    Starke, E. A., Jr.

    1997-01-01

    This is the final report of the study "Aluminum-Based Materials for High Speed Aircraft" which had the objectives (1) to identify the most promising aluminum-based materials with respect to major structural use on the HSCT and to further develop those materials and (2) to assess the materials through detailed trade and evaluation studies with respect to their structural efficiency on the HSCT. The research team consisted of ALCOA, Allied-Signal, Boeing, McDonnell Douglas, Reynolds Metals and the University of Virginia. Four classes of aluminum alloys were investigated: (1) I/M 2XXX containing Li and I/M 2XXX without Li, (2) I/M 6XXX, (3) two P/M 2XXX alloys, and (4) two different aluminum-based metal matrix composites (MMC). The I/M alloys were targeted for a Mach 2.0 aircraft and the P/M and MMC alloys were targeted for a Mach 2.4 aircraft. Design studies were conducted using several different concepts including skin/stiffener (baseline), honeycomb sandwich, integrally stiffened and hybrid adaptations (conventionally stiffened thin-sandwich skins). Alloy development included fundamental studies of coarsening behavior, the effect of stress on nucleation and growth of precipitates, and fracture toughness as a function of temperature were an integral part of this program. The details of all phases of the research are described in this final report.

  1. Subsurface Aluminum Nitride Formation in Iron-Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Bott, June H.

    Transformation-induced plasticity (TRIP) steels containing higher amounts of aluminum than conventional steels are ideal for structural automotive parts due to their mechanical properties. However, the aluminum tends to react with any processing environment at high temperatures and therefore presents significant challenges during manufacturing. One such challenge occurs during secondary cooling, reheating, and hot-rolling and is caused by a reaction with nitrogen-rich atmospheres wherein subsurface aluminum nitride forms in addition to internal and external oxides. The nitrides are detrimental to mechanical properties and cause surface cracks. It is important to understand how these nitrides and oxides form and their consequences for the quality of steel products. This study looks at model iron-aluminum (up to 8 wt.% aluminum) alloys and uses confocal laser scanning microscopy, x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectrometry, and transmission electron microscopy to study the effect of various conditions on the growth and development of these precipitates in a subsurface oxygen-depleted region. By using model alloys and controlling the experimental atmosphere, this study is able to understand some of the more fundamental materials science behind aluminum nitride formation in aluminum-rich iron alloys and the relationship between internal nitride and oxide precipitation and external oxide scale morphology and composition. The iron-aluminum alloys were heated in N2 atmospheres containing oxygen impurities. It was found that nitrides formed when bulk aluminum content was below 8 wt.% when oxygen was sufficiently depleted due to the internal oxidation. In the samples containing 1 wt.% aluminum, the depth of the internal oxide and nitride zones were in agreement with a diffusion-based model. Increasing aluminum content to 3 and 5 wt% had the effects of modifying the surface-oxide scale composition and increasing its continuity, which gradually decreased the internal precipitation zones with increasing aluminum content. In samples containing 8 wt.% aluminum, a thick continuous oxide scale formed and prevented nitrogen and oxygen penetration into the bulk of the sample, thus preventing the formation of any internal precipitates. The effect of modifying the heating rate in pure N2 atmospheres was examined. Samples were heated over the course of 1, 10, or 100 minutes. Faster heating rates increased the aluminum content in the oxide scale on all samples. Additionally, these rapid heating rate samples had either had lower internal precipitation depths or no internal precipitates. Experiments were conducted in N2--2.5% H2/H 2O mixtures with varying dew points to lower the oxygen potential of the reaction gas and prevent the formation of external iron oxide scales. In the 3 and 5 wt.% Al alloys, this produced an internal aluminum-rich oxide band which inhibited further internal precipitation. Samples treated in atmospheres to simulate the reheat furnace combustion atmosphere experienced dramatically increased external oxidation in addition to inward growth of the oxide scale and internal precipitation of oxides and nitrides within the metal. The most important scientific findings of this dissertation are the dramatic effect of heating rate on modifying the external scale of the alloys presented and the presence of continuous internal oxide bands in several samples throughout the study. Oxidation studies typically occur for longer times and in higher oxygen contents than the present results, so the influence of heating rate is either largely unnoticed or is overcome by oxide growth at long times. Oxide bands have been observed in literature, but few aluminum oxide bands have been seen before this study. vi.

  2. Aluminum hydroxide issue closure package

    SciTech Connect

    Bergman, T.B.

    1998-08-26

    Aluminum hydroxide coatings on fuel elements stored in aluminum canisters in K West Basin were measured in July and August 1998. Good quality data was produced that enabled statistical analysis to determine a bounding value for aluminum hydroxide at a 99% confidence level. The updated bounding value is 10.6 kg per Multi-Canister Overpack (MCO), compared to the previously estimated bounding value of 8 kg/MCO. Thermal analysis using the updated bounding value, shows that the MCO generates oxygen concentrate that are below the lower flammability limits during the 40-year interim storage period and are, therefore, acceptable.

  3. Plasma Source Ion Implantation of Aluminum and Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Walter, Kevin Carl

    Three plasma source ion implantation (PSII) schemes applied to three aluminum systems have been studied. Pure aluminum, and aluminum alloys 7075 (Al-Cu-Mg-Zn) and A390 (Al-17Si-Cu-Fe) were (1) argon ion sputter-cleaned and nitrogen-implanted, (2) nitrogen-implanted without sputter -cleaning, and (3) argon-implanted. Nitrogen implantation was performed with the goal of modifying the surface properties by transformation of the surface to aluminum-nitride. Argon implantation was performed with the goal of modifying the surface properties by inducing radiation damage. All implantation schemes were accomplished using a glow discharge mode of the PSII process. Implanted surfaces were investigated using Auger depth profiling and Transmission Electron Microscopy. The profiles indicated a stoichiometric layer, ~ 0.15 ?m thick, of AlN on the nitrogen-implanted samples. Electron microscopy confirmed the complete conversion of the aluminum surface to AlN. Knoop microhardness tests showed an increase in surface hardness, especially at low loads. The improvements were independent of prior sputter-cleaning and were approximately equal for the studied aluminum systems. Pin-on-disk wear tests were conducted using a ruby stylus and isopropanol lubrication. Argon implantation decreased the wear resistance of pure aluminum and 7075. Nitrogen implantation improved the wear rates by a factor of ~10 for pure aluminum and 7075. These improvements were independent of prior sputter-cleaning. The coefficient of friction was not significantly influenced by the implantation schemes. Due to a coarse microstructure, tribological tests of ion-implanted A390 were inconclusive. Corrosion studies performed in a 3.5 wt% NaCl solution (seawater) indicated nitrogen implantation gave pure aluminum improved corrosion resistance. The improvement is due to the complete conversion of the aluminum surface to AlN. Because of pre-existing precipitates, the corrosion properties of 7075 and A390 were not significantly affected. This work demonstrated significant modification of the tribological and electrochemical properties of the aluminum surface can be accomplished using nitrogen plasma source ion implantation.

  4. Simulating the Response of a Composite Honeycomb Energy Absorber. Part 2; Full-Scale Impact Testing

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Annett, Martin S.; Jackson, Karen E.; Polanco, Michael A.

    2012-01-01

    NASA has sponsored research to evaluate an externally deployable composite honeycomb designed to attenuate loads in the event of a helicopter crash. The concept, designated the Deployable Energy Absorber (DEA), is an expandable Kevlar(Registered TradeMark) honeycomb. The DEA has a flexible hinge that allows the honeycomb to be stowed collapsed until needed during an emergency. Evaluation of the DEA began with material characterization of the Kevlar(Registered TradeMark)-129 fabric/epoxy, and ended with a full-scale crash test of a retrofitted MD-500 helicopter. During each evaluation phase, finite element models of the test articles were developed and simulations were performed using the dynamic finite element code, LS-DYNA(Registered TradeMark). The paper will focus on simulations of two full-scale impact tests involving the DEA, a mass-simulator and a full-scale crash of an instrumented MD-500 helicopter. Isotropic (MAT24) and composite (MAT58) material models, which were assigned to DEA shell elements, were compared. Based on simulations results, the MAT58 model showed better agreement with test.

  5. Carbon honeycomb grids for advanced lead-acid batteries. Part II: Operation of the negative plates

    NASA Astrophysics Data System (ADS)

    Kirchev, A.; Dumenil, S.; Alias, M.; Christin, R.; de Mascarel, A.; Perrin, M.

    2015-04-01

    The article presents the recent progress in the carbon honeycomb grid technology for valve-regulated lead-acid batteries with absorptive glass-mat separators (AGM-VRLAB). The work is focused on the development of negative current collectors using industrial grade composite honeycomb precursors. The developed model AGM-VRLA cells comprised of one prototype honeycomb negative electrode and two conventional traction positive counter-electrodes show high utilisation of the negative active material and long cycle life both in high-rate partial state of charge (HRPSoC) cycling mode and in deep cycling mode. The analysis of the results from the cycle-life tests and the tear-down analysis indicate that the benefits delivered by the novel grids can be related to the low mesh size of the grid, low ?-coefficient, as well as the use of milled carbon fibre additive. The combination of the three, results in the reversibility of the negative active material sulfation process when the electrolyte concentration in the cells is lower than the one traditionally used in the AGM-VRLAB technology. The negative plates show no signs of irreversible degradation after more than 900 cycles in deep cycling mode and more than 2000 capacity turnovers (equivalent cycles) in HRPSoC cycling mode.

  6. Multipulse Chaotic Dynamics of Six-Dimensional Nonautonomous Nonlinear System for a Honeycomb Sandwich Plate

    NASA Astrophysics Data System (ADS)

    Hao, W. L.; Zhang, W.; Yao, M. H.

    This paper studies the global bifurcations and multipulse chaotic dynamics of a four-edge simply supported honeycomb sandwich rectangular plate under combined in-plane and transverse excitations. Based on the von Karman type equation for the geometric nonlinearity and Reddy's third-order shear deformation theory, the governing equations of motion are derived for the four-edge simply supported honeycomb sandwich rectangular plate. The Galerkin method is employed to discretize the partial differential equations of motion to a three-degree-of-freedom nonlinear system. The six-dimensional nonautonomous nonlinear system is simplified to a three-order standard form by using the normal form method. The extended Melnikov method is improved to investigate the six-dimensional nonautonomous nonlinear dynamical system in a mixed coordinate. The global bifurcations and multipulse chaotic dynamics of the four-edge simply supported honeycomb sandwich rectangular plate are studied by using the improved extended Melnikov method. The multipulse chaotic motions of the system are found by using numerical simulation, which further verifies the result of theoretical analysis.

  7. Bondonic effects in group-IV honeycomb nanoribbons with Stone-Wales topological defects.

    PubMed

    Putz, Mihai V; Ori, Ottorino

    2014-01-01

    This work advances the modeling of bondonic effects on graphenic and honeycomb structures, with an original two-fold generalization: (i) by employing the fourth order path integral bondonic formalism in considering the high order derivatives of the Wiener topological potential of those 1D systems; and (ii) by modeling a class of honeycomb defective structures starting from graphene, the carbon-based reference case, and then generalizing the treatment to Si (silicene), Ge (germanene), Sn (stannene) by using the fermionic two-degenerate statistical states function in terms of electronegativity. The honeycomb nanostructures present ?-sized Stone-Wales topological defects, the isomeric dislocation dipoles originally called by authors Stone-Wales wave or SWw. For these defective nanoribbons the bondonic formalism foresees a specific phase-transition whose critical behavior shows typical bondonic fast critical time and bonding energies. The quantum transition of the ideal-to-defect structural transformations is fully described by computing the caloric capacities for nanostructures triggered by ?-sized topological isomerisations. Present model may be easily applied to hetero-combinations of Group-IV elements like C-Si, C-Ge, C-Sn, Si-Ge, Si-Sn, Ge-Sn. PMID:24705562

  8. First-principles study of defects and adatoms in silicon carbide honeycomb structures

    NASA Astrophysics Data System (ADS)

    Bekaroglu, E.; Topsakal, M.; Cahangirov, S.; Ciraci, S.

    2010-02-01

    We present a study of mechanical, electronic and magnetic properties of two-dimensional (2D), monolayer of silicon carbide (SiC) in honeycomb structure and its quasi-one-dimensional (quasi-1D) armchair nanoribbons using first-principles plane-wave method. In order to reveal dimensionality effects, a brief study of three-dimensional (3D) bulk and 1D atomic chain of SiC are also included. Calculated bond-lengths, cohesive energies, charge transfers and band gaps display a clear dimensionality effect. The stability analysis based on the calculation of phonon frequencies indicates that 2D SiC monolayer is stable in planar geometry. We found that 2D SiC monolayer in honeycomb structure and its bare and hydrogen passivated nanoribbons are ionic, nonmagnetic, wide band gap semiconductors. The band gap is further increased upon self-energy corrections. The mechanical properties are investigated using the strain energy calculations. The effect of various vacancy defects, adatoms, and substitutional impurities on electronic and magnetic properties in 2D SiC monolayer and in its armchair nanoribbons is also investigated. Some of these vacancy defects and impurities, which are found to influence physical properties and attain magnetic moments, can be used to functionalize SiC honeycomb structures.

  9. When block copolymer self-assembly in hierarchically ordered honeycomb films depicts the breath figure process.

    PubMed

    Escalé, Pierre; Save, Maud; Billon, Laurent; Ruokolainen, Janne; Rubatat, Laurent

    2016-01-21

    Nowadays, a challenge in the preparation of hierarchically ordered materials is the control of concomitant and interacting self-organization processes occurring in time at different length scales. In the present paper, the breath figure process is combined with block copolymer nano-phase segregation to elaborate hierarchically structured honeycomb porous films. Copolymer ordering, at the nanometer length scale, is observed and described in detail with respect to the array of pores of micrometer dimension, hence pointing out the structural interplays between both length-scales. The study is focused on two diblock copolymers made of polystyrene and poly(tert-butyl acrylate) (PS-b-PtBA) with compositions producing lamellae or hexagonal packing of cylinders at thermodynamical equilibrium. Transmission Electron Microscopy completed with Small and Ultra-Small Angle Scattering are performed to evidence the inner morphologies of the honeycomb. The structural data are discussed in the light of the honeycomb film formation process establishing the interest in using kinetically trapped block copolymer self-organization as an imprint to elucidate the complex breath figure process. PMID:26528753

  10. Experimental and Analytical Evaluation of a Composite Honeycomb Deployable Energy Absorber

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Kellas, Sotiris; Horta, Lucas G.; Annett, Martin S.; Polanco, Michael A.; Littell, Justin D.; Fasanella, Edwin L.

    2011-01-01

    In 2006, the NASA Subsonic Rotary Wing Aeronautics Program sponsored the experimental and analytical evaluation of an externally deployable composite honeycomb structure that is designed to attenuate impact energy during helicopter crashes. The concept, which is designated the Deployable Energy Absorber (DEA), utilizes an expandable Kevlar honeycomb structure to dissipate kinetic energy through crushing. The DEA incorporates a unique flexible hinge design that allows the honeycomb to be packaged and stowed flat until needed for deployment. A variety of deployment options such as linear, radial, and/or hybrid methods can be used. Experimental evaluation of the DEA utilized a building block approach that included material characterization testing of its constituent, Kevlar -129 fabric/epoxy, and flexural testing of single hexagonal cells. In addition, the energy attenuation capabilities of the DEA were demonstrated through multi-cell component dynamic crush tests, and vertical drop tests of a composite fuselage section, retrofitted with DEA blocks, onto concrete, water, and soft soil. During each stage of the DEA evaluation process, finite element models of the test articles were developed and simulations were performed using the explicit, nonlinear transient dynamic finite element code, LS-DYNA. This report documents the results of the experimental evaluation that was conducted to assess the energy absorption capabilities of the DEA.

  11. Formation and soot combustion of honeycomb-like LaFeO3 microfibers.

    PubMed

    Zou, Lianli; Jing, Maoxiang; Xiang, Jun; Wang, Pan; Shen, Xiangqian

    2014-03-01

    The nanocrystalline, honeycomb-like, perovskite LaFeO3 microfibers with a fibre diameter about 1-2 microm and channel sizes about 180-220 nm on the cross-section were prepared by the citrate-gel process. These microfibers were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and Brunauere-Emmette-Teller (BET) method. After calcined at a low temperature of 550 degrees C for 6 hours, the single phase of perovskite LaFeO3 microfibers is formed and the grain size increases from 27 to 38 nm with the calcination temperature increasing from 500 to 650 degrees C. The catalytic activity for soot combustion was analyzed by thermo-gravimetric method (TG), and the LaFeO3 microfibers calcined at 600 degrees C exhibits the highest catalytic activity for soot combustion, with a lowest T50 (393 degrees C) and T90 (434 degrees C). The formation mechanism of the honeycomb-like structure is analyzed and these honeycomb-like microfibers can be used as advanced catalysts, absorbents, filters and microreactors. PMID:24745245

  12. Thermodynamic Study of 3D ``Harmonic'' Honeycomb Li2IrO3

    NASA Astrophysics Data System (ADS)

    Ruiz, Alejandro; Helm, Toni; Breznay, Nicholas; Lopez, Gilbert; Analytis, James

    2015-03-01

    Honeycomb iridates have been the focus of substantial interest due to the strong magnetic frustration that arises from their edge-shared bonding environment, which favors a strongly anisotropic Ising-like exchange between bonds. In materials with edge-shared IrO6 octahedra, spin-anisotropy of the exchange between neighboring effective spin-1/2 states is enhanced by the interference of the two exchange paths across the planar Ir-O2-Ir bond. In the honeycomb lattice, such an interaction couples different orthogonal spin components for the three nearest neighbors; no single exchange direction can be simultaneously satisfied, leading to strong frustration which can be described by the Kitaev-model. We have recently synthesized a new structure that retains the same bonding environment as the honeycomb lattice, and extends this physics to three-dimensions. Previous RMXD experiments on our orthorhombic ? < 1 > -Li2IrO3 samples revealed an incommensurate, non-coplanar magnetic structure with counter-rotating moments, suggesting that Kitaev exchange is the dominant spin interaction in this system. In this work, we study the thermal properties of our single crystals as a function of temperature and applied magnetic field. Berkeley Chancellor's Fellowship & NSF-GRFP.

  13. ESCA studies of yttrium aluminum garnets

    SciTech Connect

    Pawlak, D.A.; Wozniak, K.; Frukacz, Z.; Barr, T.L.; Fiorentino, D.; Seal, S.

    1999-03-04

    X-ray photoelectron spectroscopy (XPS/ESCA) has been employed to investigate pure single crystals and powdered samples of yttrium aluminum garnet, Y{sub 3}Al{sub 5}O{sub 12} (YAG), and YAG crystals doped with several rare earth elements (Ln = Pr, Er, Ho, Tm) and a transition metal (Cr). Core level XPS peak shapes of the main elements forming the garnet structure can be rationalized due to different structural environments of particular ions modified by doping. The change of dopant oxidation state also results in variation of XPS peaks and helps to identify the sites in which it takes place. Single-crystal and powder samples give different XPS spectra. Possible sources of these differences are discussed. Similarities and differences between simple and mixed oxides are shown. The structure of YAG suggests the presence of only one independent oxygen ion; however the O(1s) spectra of all YAG systems exhibit two readily discerned peaks. An explanation for this dichotomy is discussed, involving the possible polarization of the oxygen valence electron density between the aluminum and yttrium. Alternative explanations are also considered.

  14. Electrolyte treatment for aluminum reduction

    DOEpatents

    Brown, Craig W. (Seattle, WA); Brooks, Richard J. (Seattle, WA); Frizzle, Patrick B. (Seattle, WA); Juric, Drago D. (Bulleen, AU)

    2002-01-01

    A method of treating an electrolyte for use in the electrolytic reduction of alumina to aluminum employing an anode and a cathode, the alumina dissolved in the electrolyte, the treating improving wetting of the cathode with molten aluminum during electrolysis. The method comprises the steps of providing a molten electrolyte comprised of ALF.sub.3 and at least one salt selected from the group consisting of NaF, KF and LiF, and treating the electrolyte by providing therein 0.004 to 0.2 wt. % of a transition metal or transition metal compound for improved wettability of the cathode with molten aluminum during subsequent electrolysis to reduce alumina to aluminum.

  15. Chrome - Free Aluminum Coating System

    NASA Technical Reports Server (NTRS)

    Bailey, John H.; Gugel, Jeffrey D.

    2010-01-01

    This slide presentation concerns the program to qualify a chrome free coating for aluminum. The program was required due to findings by OSHA and EPA, that hexavalent chromium, used to mitigate corrosion in aerospace aluminum alloys, poses hazards for personnel. This qualification consisted of over 4,000 tests. The tests revealed that a move away from Cr+6, required a system rather than individual components and that the maximum corrosion protection required pretreatment, primer and topcoat.

  16. Preparation and characterization of energetic materials coated superfine aluminum particles

    NASA Astrophysics Data System (ADS)

    Liu, Songsong; Ye, Mingquan; Han, Aijun; Chen, Xin

    2014-01-01

    This work is devoted to protect the activity of aluminum in solid rocket propellants by means of solvent/non-solvent method in which nitrocellulose (NC) and Double-11 (shortened form of double-base gun propellant, model 11) have been used as coating materials. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the morphology of coated Al particles. Other characterization data of coated and uncoated Al particles, such as infrared absorption spectrum, laser particle size analysis and the active aluminum content were also studied. The thermal behavior of pure and coated aluminum samples have also been studied by simultaneous thermogravimetry-differential thermal analysis (TG-DTA) and differential scanning calorimetry (DSC). The results indicated that: superfine aluminum particles could be effectively coated with nitrocellulose and Double-11 through a solvent/non-solvent method. The energetic composite particles have core-shell structures and the thickness of the coating film is about 20-50 nm. The active aluminum content of different coated samples was measured by means of oxidation-reduction titration method. The results showed that after being stored in room temperature and under 50% humidity condition for about 4months the active aluminum content of coated Al particles decreased from 99.8 to 95.8% (NC coating) and 99.2% (Double-11 coating) respectively. Double-11 coating layer had a much better protective effect. The TG-DTA and DSC results showed that the energy amount and energy release rate of NC coated and Double-11 coated Al particles were larger than those of the raw Al particles. Double-11 coated Al particles have more significant catalytic effect on the thermal decomposition characters of AP than that of NC coated Al particles. These features accorded with the energy release characteristics of solid propellant.

  17. Biophysical aspects of aluminum intoxication

    SciTech Connect

    Weis, C.P.

    1987-01-01

    This thesis is directed toward defining mechanisms of aluminum toxicity from a biophysical perspective. Studies included focus on the ability of toxic aluminum species and altered pH to damage or modulate association between the calcium regulatory protein calmodulin and model target proteins. The role of pH and aluminum in alteration of plasma membrane lipid order and fluidity is investigated using time resolved fluorescence polarization. Using circular dichroism, time resolved fluorescence, and enzyme assay, pH is shown to modulate the conformation and function of calmodulin within the physiological pH range. The role of aluminum in disturbing the binding between calmodulin and melittin or mastoparan, model targets for calmodulin function is defined. Membrane disturbances induced by aluminum and altered pH are investigated in chapter four and appendix C. Time resolved dynamic motion of the membrane probe DPH, and proton sensitive fluorescence probes are used to monitor proton pumping and membrane fluidity in response to aluminum and acid stress.

  18. Aluminum laser welding optimization

    NASA Astrophysics Data System (ADS)

    Chmelí?ková, Hana; Halenka, Viktor; Lapšanská, Hana; Havelková, Martina

    2007-04-01

    Pulsed Nd:YAG laser with maximal power 150 W is used in our laboratory to cut, drill and weld metal and non-metal thin materials to thickness 2 mm. Welding is realized by fixed processing head or movable fiber one with beam diameter 0,6 mm in focus plane. Welding of stainless and low-carbon steel was tested before and results are publicized and used in practice. Now the goal of our experiment was optimization of process parameters for aluminum that has other physical properties than steels, lower density, higher heat conductivity and surface reflexivity. Pure alumina specimen 0,8 mm and Al-Mg-Si alloy 0,5 mm prepared for butt welds. Problem with surface layer of Al IIO 3 was overcome by sanding and chemical cleaning with grinding paste. Critical parameters for good weld shape are specimen position from beam focus plane, pulse length and energy, pulse frequency and the motion velocity that determines percentage of pulse overlap. Argon as protective gas was used with speed 6 liters per second. Thermal distribution in material can be modeled by numerical simulation. Software tool SYSWELD makes possible to fit laser as surface heat source, define weld geometry, and make meshing of specimen to finite elements and compute heat conduction during process. Color isotherms, vectors, mechanical deformations and others results can be study in post-processing.

  19. Commonwealth Aluminum: Manufacturer Conducts Plant-Wide Energy Assessments at Two Aluminum Sheet Production Operations;

    SciTech Connect

    Not Available

    2006-04-01

    DOE Industrial Technologies Program case study describes the savings possible if Commonwealth Aluminum (now Aleris Rolled Products) makes improvements noted in energy assessments at two aluminum mills.

  20. Effects of load voltage on voltage breakdown modes of electrical exploding aluminum wires in air

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Li, Xingwen; Yang, Zefeng; Wang, Kun; Chao, Youchuang; Shi, Zongqian; Jia, Shenli; Qiu, Aici

    2015-06-01

    The effects of the load voltage on the breakdown modes are investigated in exploding aluminum wires driven by a 1 kA, 0.1 kA/ns pulsed current in air. From laser probing images taken by laser shadowgraphy, schlieren imaging, and interferometry, the position of the shockwave front, the plasma channel, and the wire core edge of the exploding product can be determined. The breakdown mode makes a transition from the internal mode, which involves breakdown inside the wire core, to the shunting mode, which involves breakdown in the compressed air, with decreasing charging voltage. The breakdown electrical field for a gaseous aluminum wire core of nearly solid density is estimated to be more than 20 kV/cm, while the value for gaseous aluminum of approximately 0.2% solid density decreases to 15-20 kV/cm. The breakdown field in shunting mode is less than 20 kV/cm and is strongly affected by the vaporized aluminum, the desorbed gas, and the electrons emitted from the wire core during the current pause. Ohmic heating during voltage collapses will induce further energy deposition in the current channel and thus will result in different expansion speeds for both the wire core and the shockwave front in the different modes.

  1. 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

    sandwich panel structures Gregory W. Kooistra, Douglas T. Queheillalt, Haydn N.G. Wadley Department hardenable 6061 aluminum tetrahedral lattice truss core sandwich panels have been fabricated by folding perforated sheets to form highly flexible cellular cores. Flat or curved sandwich panels can be fabricated

  2. System integration and demonstration of adhesive bonded high temperature aluminum alloys for aerospace structure, phase 2

    NASA Technical Reports Server (NTRS)

    Falcone, Anthony; Laakso, John H.

    1993-01-01

    Adhesive bonding materials and processes were evaluated for assembly of future high-temperature aluminum alloy structural components such as may be used in high-speed civil transport aircraft and space launch vehicles. A number of candidate high-temperature adhesives were selected and screening tests were conducted using single lap shear specimens. The selected adhesives were then used to bond sandwich (titanium core) test specimens, adhesive toughness test specimens, and isothermally aged lap shear specimens. Moderate-to-high lap shear strengths were obtained from bonded high-temperature aluminum and silicon carbide particulate-reinforced (SiC(sub p)) aluminum specimens. Shear strengths typically exceeded 3500 to 4000 lb/in(sup 2) and flatwise tensile strengths exceeded 750 lb/in(sup 2) even at elevated temperatures (300 F) using a bismaleimide adhesive. All faceskin-to-core bonds displayed excellent tear strength. The existing production phosphoric acid anodize surface preparation process developed at Boeing was used, and gave good performance with all of the aluminum and silicon carbide particulate-reinforced aluminum alloys investigated. The results of this program support using bonded assemblies of high-temperature aluminum components in applications where bonding is often used (e.g., secondary structures and tear stoppers).

  3. Aluminum industry applications for OTEC

    SciTech Connect

    Jones, M.S.; Leshaw, D.; Sathyanarayana, K.; Sprouse, A.M.; Thiagarajan, V.

    1980-12-01

    The objective of the program is to study the integration issues which must be resolved to realize the market potential of ocean thermal energy conversion (OTEC) power for the aluminum industry. The study established, as a baseline, an OTEC plant with an electrical output of 100 MWe which would power an aluminum reduction plant. The reduction plant would have a nominal annual output of about 60,000 metric tons of aluminum metal. Three modes of operation were studied, viz: 1. A reduction plant on shore and a floating OTEC power plant moored offshore supplying energy by cable. 2. A reduction plant on shore and a floating OTEC power plant at sea supplying energy by means of an ''energy bridge.'' 3. A floating reduction plant on the same platform as the OTEC power plant. For the floating OTEC/aluminum plantship, three reduction processes were examined. 1. The conventional Hall process with prebaked anodes. 2. The drained cathode Hall cell process. 3. The aluminum chloride reduction process.

  4. Scaleable Clean Aluminum Melting Systems

    SciTech Connect

    Han, Q.; Das, S.K.

    2008-02-15

    The project entitled 'Scaleable Clean Aluminum Melting Systems' was a Cooperative Research and Development Agreements (CRADAs) between Oak Ridge National Laboratory (ORNL) and Secat Inc. The three-year project was initially funded for the first year and was then canceled due to funding cuts at the DOE headquarters. The limited funds allowed the research team to visit industrial sites and investigate the status of using immersion heaters for aluminum melting applications. Primary concepts were proposed on the design of furnaces using immersion heaters for melting. The proposed project can continue if the funding agency resumes the funds to this research. The objective of this project was to develop and demonstrate integrated, retrofitable technologies for clean melting systems for aluminum in both the Metal Casting and integrated aluminum processing industries. The scope focused on immersion heating coupled with metal circulation systems that provide significant opportunity for energy savings as well as reduction of melt loss in the form of dross. The project aimed at the development and integration of technologies that would enable significant reduction in the energy consumption and environmental impacts of melting aluminum through substitution of immersion heating for the conventional radiant burner methods used in reverberatory furnaces. Specifically, the program would couple heater improvements with furnace modeling that would enable cost-effective retrofits to a range of existing furnace sizes, reducing the economic barrier to application.

  5. DNA-lipid complexes: stability of honeycomb-like and spaghetti-like structures.

    PubMed Central

    May, S; Ben-Shaul, A

    1997-01-01

    A molecular level theory is presented for the thermodynamic stability of two (similar) types of structural complexes formed by (either single strand or supercoiled) DNA and cationic liposomes, both involving a monolayer-coated DNA as the central structural unit. In the "spaghetti" complex the central unit is surrounded by another, oppositely curved, monolayer, thus forming a bilayer mantle. The "honeycomb" complex is a bundle of hexagonally packed DNA-monolayer units. The formation free energy of these complexes, starting from a planar cationic/neutral lipid bilayer and bare DNA, is expressed as a sum of electrostatic, bending, mixing, and (for the honeycomb) chain frustration contributions. The electrostatic free energy is calculated using the Poisson-Boltzmann equation. The bending energy of the mixed lipid layers is treated in the quadratic curvature approximation with composition-dependent bending rigidity and spontaneous curvature. Ideal lipid mixing is assumed within each lipid monolayer. We found that the most stable monolayer-coated DNA units are formed when the charged/neutral lipid composition corresponds (nearly) to charge neutralization; the optimal monolayer radius corresponds to close DNA-monolayer contact. These conclusions are also valid for the honeycomb complex, as the chain frustration energy is found to be negligible. Typically, the stabilization energies for these structures are on the order of 1 k(B)T/A of DNA length, reflecting mainly the balance between the electrostatic and bending energies. The spaghetti complexes are less stable due to the additional bending energy of the external monolayer. A thermodynamic analysis is presented for calculating the equilibrium lipid compositions when the complexes coexist with excess bilayer. PMID:9370436

  6. Steam explosions of single drops of core-melt simulants

    SciTech Connect

    Nelson, L.S. ); Hyndman, D.A.; Duda, P.M. )

    1991-01-01

    We have studied triggering of fuel-coolant interactions, the work performed against the surrounding coolant during the interaction, and the generation of hydrogen produced by melt-water chemical reactions with laboratory-scale experiments. We used single drops of three core- melt simulants: (a) molten stoichiometric thermite-generated iron- aluminum oxide melts to simulate the core-melt material that might be produced in the severe accident of an oxide-fueled reactor; (b) molten aluminum to simulate melt that might be produced in the severe accident of a nonpower reactor; and (c) an intermediate material, aluminum-enriched iron-aluminum oxide thermite, that might simulate severe meltdown of an oxide-metal dispersion fuel (cermet). As a result of these experiments, we have concluded that the peak pressure (or impulse) of the transient is not a governing parameter for the triggering of steam explosions of single drops of melt. We have observed maximum pressure-volume work outputs produced by the aluminum-rich and stoichiometric thermite melts of about 70 and 25 J/g of melt; the corresponding values for molten aluminum at 1273 and 1473 K are about 14 and 21 J/g of melt. The extent of metal-water reaction for the stoichiometric and aluminized melts were 13 and 19%. The aluminum melts at 1273 and 1473 K produced approximately 1 and 3% metal-water reaction. 5 refs., 7 figs.

  7. Oxidation of ligand-protected aluminum clusters: An ab initio molecular dynamics study

    SciTech Connect

    Alnemrat, Sufian; Hooper, Joseph P.

    2014-03-14

    We report Car-Parrinello molecular dynamics simulations of the oxidation of ligand-protected aluminum clusters that form a prototypical cluster-assembled material. These clusters contain a small aluminum core surrounded by a monolayer of organic ligand. The aromatic cyclopentadienyl ligands form a strong bond with surface Al atoms, giving rise to an organometallic cluster that crystallizes into a low-symmetry solid and is briefly stable in air before oxidizing. Our calculations of isolated aluminum/cyclopentadienyl clusters reacting with oxygen show minimal reaction between the ligand and O{sub 2} molecules at simulation temperatures of 500 and 1000 K. In all cases, the reaction pathway involves O{sub 2} diffusing through the ligand barrier, splitting into atomic oxygen upon contact with the aluminum, and forming an oxide cluster with aluminum/ligand bonds still largely intact. Loss of individual aluminum-ligand units, as expected from unimolecular decomposition calculations, is not observed except following significant oxidation. These calculations highlight the role of the ligand in providing a steric barrier against oxidizers and in maintaining the large aluminum surface area of the solid-state cluster material.

  8. A comparison of the static and dynamic characteristics of straight-bore and convergent tapered-bore honeycomb annular gas seals 

    E-print Network

    Dawson, Matthew Peter

    2000-01-01

    Results are presented from tests conducted with straight-bore and convergent tapered-bore honeycomb annular gas seals. The test seals had a 114.3 mm bore with an L/D = 0.75 and a nominal radial clearance of 0.19 mm. The honeycomb cell depth for both...

  9. A comparison of experimental and theoretical results for labyrinth gas seals with honeycomb stators. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Hawkins, Lawrence Allen

    1988-01-01

    Experimental results for the rotordynamic stiffness and damping coefficients of a labyrinth -rotor honeycomb-stator seal are presented. The coefficients are compared to the coefficients of a labyrinth-rotor smooth-stator seal having the same geometry. The coefficients are compared to analytical results from a two-control-volume compressible flow model. The experimental results show that the honeycomb stator configuration is more stable than the smooth stator configuration at low rotor speeds. At high rotor speeds and low clearance, the smooth stator seal is more stable. The theoretical model predicts the cross-coupled stiffness of the honeycomb stator seal correctly within 25 percent of measured values. The model provides accurate predictions of direct damping for large clearance seals. Overall, the model does not perform as well for low clearance seals as for high clearance seals.

  10. Assembly of acid and sintering resistant honeycomb washcoat and catalytically active phase using sols of silica, zirconia, and platinum

    SciTech Connect

    Felthouse, T.R.; Berkel, D.A.; Jost, S.R.

    1995-12-01

    Development of high performance honeycomb catalysts containing platinum active phase for gas phase air oxidation of sulfur dioxide is described. Stepwise assembly of these washcoated honeycombs consists of: (1) selection of honeycomb composition (mullite substrate) and cell density based on pressure drop requirements; (2) identification of washcoat slurry composition (silica-precursor sol, silica powder, and surfactants if needed); (3) processing of the washcoat-substrate by dip coating, drying, and calcining; (4) loading of the platinum active phase through a facilitated adsorption technique followed by drying and activation steps; and (5) reactor loading and evaluation. Details of these steps will be presented that include thermal and chemical stability tests. Characterization by transmission electron microscopy of the final Pt/(ZrO{sub 2}-SiO{sub 2}) composite attached to the mullite substrate will be reported.

  11. Experimental results for labyrinth gas seals with honeycomb stators - Comparisons to smooth-stator seals and theoretical predictions

    NASA Technical Reports Server (NTRS)

    Hawkins, Larry; Childs, Dara; Hale, Keith

    1989-01-01

    Experimental measurements are presented for the rotordynamic stiffness and damping coefficients of a teeth-on-rotor labyrinth seal with a honeycomb stator. Inlet circumferential velocity, inlet pressure, rotor speed, and seal clearance are primary variables. Results are compared to data for teeth-on-rotor labyrinth seals with smooth stators and to analytical predictions from a two-control-volume compressible flow model. The experimental results show that the honeycomb-stator configuration is more stable than the smooth-stator configuration at low rator speeds. At high rotor speeds, the stator surface does not affect stability. The theoretical model predicts the cross-coupled stiffness of the honeycomb-stator seal correctly within 25 percent of measured values. The model provides accurate predictions of direct damping for large clearance seals; however, the model predictions and test results diverge with increasing running speed. Overall, the model does not perform as well for low clearance seals as for high clearance seals.

  12. How to directly observe Landau levels in driven-dissipative strained honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Salerno, Grazia; Ozawa, Tomoki; Price, Hannah M.; Carusotto, Iacopo

    2015-09-01

    We study the driven-dissipative steady-state of a coherently driven Bose field in a honeycomb lattice geometry. In the presence of a suitable spatial modulation of the hopping amplitudes, a valley-dependent artificial magnetic field appears and the low-energy eigenmodes have the form of relativistic Landau levels. We show how the main properties of the Landau levels can be extracted by observing the peaks in the absorption spectrum of the system and the corresponding spatial intensity distribution. Finally, quantitative predictions for realistic lattices based on photonic or microwave technologies are discussed.

  13. Possible phase separation in square and honeycomb Hubbard model: A variational cluster study

    NASA Astrophysics Data System (ADS)

    Fang, Kun; Fernando, G. W.; Balatsky, A. V.; Kocharian, A. N.

    2015-10-01

    The VCA ground state of the 2D Hubbard model is examined for possible phase separation under hole doping manifested by spatial inhomogeneities of coexisting different electron densities at equilibrium. Phase separation is accompanied by spectral weight loss and first Brillouin zone boundary deformation. Such an instability is observed in square structures and it is absent in honeycomb lattices. To our knowledge, no previous publications have revealed relationship between a Fermi surface instability and phase separation. Our VCA calculations provide strong support for this spontaneous instability, driven by electron correlations in specific lattice geometries, proposed in our earlier publications using exact quantum cluster calculations.

  14. 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.

  15. Power-law spin correlations in a perturbed spin model on a honeycomb lattice.

    PubMed

    Tikhonov, K S; Feigel'man, M V; Kitaev, A Yu

    2011-02-11

    We consider the spin-1/2 model on the honeycomb lattice in the presence of a weak magnetic field h? < 1. Such a perturbation destroys the exact integrability of the model in terms of gapless fermions and static Z2 fluxes. We show that it results in the appearance of a long-range tail in the irreducible dynamic spin correlation function: ? h(z)(2)f(t,r), where f(t,r) ? [max(t,r)]-4 is proportional to the density polarization function of fermions. PMID:21405492

  16. Topological states with broken translational and time-reversal symmetries in a honeycomb-triangular lattice

    NASA Astrophysics Data System (ADS)

    Sarjonen, R.; Törmä, P.

    2015-06-01

    We study fermions in a lattice, with on-site and nearest neighbor attractive interactions between two spin species. We consider two geometries: (1) both spins in a triangular lattice and (2) a mixed geometry with up spins in honeycomb and down spins in triangular lattices. We focus on the interplay between spin-population imbalance, on-site and valence bond pairing, and order parameter symmetry. The mixed geometry leads to a rich phase diagram of topologically nontrivial phases. In both geometries, we predict order parameters with simultaneous time-reversal and translational symmetry breaking.

  17. Composite multi-vortex diffraction-free beams and van-Hove singularities in honeycomb lattices.

    PubMed

    Paltoglou, Vassilis; Chen, Zhigang; Efremidis, Nikolaos K

    2015-03-15

    We find diffraction-free beams for graphene and MoS2-type honeycomb optical lattices. The resulting composite solutions have the form of multi-vortices, with spinor topological charges (n, n±1). Exact solutions for the spinor components are obtained in the Dirac limit. The effects of the valley degree of freedom and the mass are analyzed. Passing through the van Hove singularity, the topological structure of the solutions is modified. Exactly at the singularity, the diffraction-free beams take the form of strongly localized one-dimensional stripes. PMID:25768176

  18. Superconductor-insulator transition in frustrated Josephson-junction arrays on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Granato, Enzo

    2014-12-01

    The zero-temperature superconductor to insulator transition is studied in a selfcharging model of Josephson-junction arrays on a honeycomb lattice in an external magnetic field corresponding to f flux quantum per plaquette. Path integral Monte Carlo simulations of the equivalent (2+1)-dimensional classical model are used to study the phase transition and critical behavior. For f = 1/3, the transition is first order. For f = 0 and f = 1/2, the transition is second order and the corresponding correlation length exponents are estimated from finite-size scaling.

  19. Quantum spin Hall effect in a two-orbital model on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Hayami, Satoru; Kusunose, Hiroaki; Motome, Yukitoshi

    2015-03-01

    The spin Hall effect is investigated in a two-orbital tight-binding model on a honeycomb lattice. We show that the model exhibits three topologically-different insulating phases at half filling, which are distinguished by different quantized values of the spin Hall conductivity. We analytically determine the phase boundaries, where the valence and conduction bands touch with each other with forming the Dirac nodes at the Fermi level. The results are discussed in terms of the effective antisymmetric spin-orbit coupling. The relation to the Kane- Mele model and implications for a magnetoelectric effect are also discussed.

  20. Temperature-induced spontaneous time-reversal symmetry breaking on the honeycomb lattice.

    PubMed

    Liu, Wei; Punnoose, Alexander

    2015-05-01

    Phase transitions involving spontaneous time-reversal symmetry breaking are studied on the honeycomb lattice at finite hole doping with next-nearest-neighbor repulsion. We derive an exact expression for the mean-field equation of state in closed form, valid at temperatures much less than the Fermi energy. Contrary to standard expectations, we find that thermally induced intraband particle-hole excitations can create and stabilize a uniform metallic phase with broken time-reversal symmetry as the temperature is raised in a region where the ground state is a trivial metal. PMID:25978244

  1. Rechargeable Aluminum-Ion Batteries

    SciTech Connect

    Paranthaman, Mariappan Parans; Liu, Hansan; Sun, Xiao-Guang; Dai, Sheng; Brown, Gilbert M

    2015-01-01

    This chapter reports on the development of rechargeable aluminum-ion batteries. A possible concept of rechargeable aluminum/aluminum-ion battery based on low-cost, earth-abundant Al anode, ionic liquid EMImCl:AlCl3 (1-ethyl-3-methyl imidazolium chloroaluminate) electrolytes and MnO2 cathode has been proposed. Al anode has been reported to show good reversibility in acid melts. However, due to the problems in demonstrating the reversibility in cathodes, alternate battery cathodes and battery concepts have also been presented. New ionic liquid electrolytes for reversible Al dissolution and deposition are needed in the future for replacing corrosive EMImCl:AlCl3 electrolytes.

  2. Recycling of aluminum salt cake

    SciTech Connect

    Jody, B.J.; Daniels, E.J.; Bonsignore, P.V.; Karvelas, D.E.

    1991-12-01

    The secondary aluminum industry generates more than 110 {times} 10{sup 3} tons of salt-cake waste every year. This waste stream contains about 3--5% aluminum, 15--30% aluminum oxide, 30--40% sodium chloride, and 20--30% potassium chloride. As much as 50% of the content of this waste is combined salt (sodium and potassium chlorides). Salt-cake waste is currently disposed of in conventional landfills. In addition, over 50 {times} 10{sup 3} tons of black dross that is not economical to reprocess a rotary furnace for aluminum recovery ends up in landfills. The composition of the dross is similar to that of salt cake, except that it contains higher concentrations of aluminum (up to 20%) and correspondingly lower amounts of salts. Because of the high solubility of the salts in water, these residues, when put in landfills, represent a potential source of pollution to surface-water and groundwater supplies. The increasing number of environmental regulations on the generation and disposal of industrial wastes are likely to restrict the disposal of these salt-containing wastes in conventional landfills. Processes exist that employ the dissolution and recovery of the salts from the waste stream. These wet-processing methods are economical only when the aluminum concentration in that waste exceeds about 10%. Argonne National Laboratory (ANL) conducted a study in which existing technologies were reviewed and new concepts that are potentially more cost-effective than existing processes were developed and evaluated. These include freeze crystallization, solvent/antisolvent extraction, common-ion effect, high-pressure/high-temperature process, and capillary-effect systems. This paper presents some of the technical and economic results of the aforementioned ANL study.

  3. Influence of insulating coating on aluminum wire explosions

    SciTech Connect

    Li, Yang; Wu, Jian; Sheng, Liang; Zhao, Jizhen; Zhang, Mei; Yuan, Yuan; Peng, Bodong; Li, Xingwen

    2014-10-15

    Single wire explosions are widely used in understanding the early stages of z-pinch experiments. This paper presents a serial of experiments conducted on the pulse power generator with ?1?kA peak current and ?10?ns rising time in Xi'an Jiao Tong University. Polyimide coated aluminum wires and uncoated ones were tested under three different voltages to analyze the effect of insulating coating. Experimental results showed that insulating coating can increase the energy deposition 10%?30% in aluminum wires by delaying the voltage collapse and raising the maximum load resistance. The substantial energy deposition resulted in about 20% faster expansion rates for coated wires. Experimental evidence that plasma channel shunts the current from the wire core was observed by streak camera and schlieren graphs. This paper also briefly discussed the influence of nonuniform coating on the morphology of wire expansion.

  4. Influence of insulating coating on aluminum wire explosions

    NASA Astrophysics Data System (ADS)

    Li, Yang; Sheng, Liang; Wu, Jian; Li, Xingwen; Zhao, Jizhen; Zhang, Mei; Yuan, Yuan; Peng, Bodong

    2014-10-01

    Single wire explosions are widely used in understanding the early stages of z-pinch experiments. This paper presents a serial of experiments conducted on the pulse power generator with ˜1 kA peak current and ˜10 ns rising time in Xi'an Jiao Tong University. Polyimide coated aluminum wires and uncoated ones were tested under three different voltages to analyze the effect of insulating coating. Experimental results showed that insulating coating can increase the energy deposition 10%˜30% in aluminum wires by delaying the voltage collapse and raising the maximum load resistance. The substantial energy deposition resulted in about 20% faster expansion rates for coated wires. Experimental evidence that plasma channel shunts the current from the wire core was observed by streak camera and schlieren graphs. This paper also briefly discussed the influence of nonuniform coating on the morphology of wire expansion.

  5. BIOLOGICAL SPECIATION AND TOXICOKINETICS OF ALUMINUM

    EPA Science Inventory

    This review discusses recent literature on the chemical and physiological factors that result in the absorption, distribution, and excretion of aluminum in mammals, with particular regard to gastrointestinal absorption and speciation in plasma. umans encounter aluminum, a ubiquit...

  6. 75 FR 80527 - Aluminum Extrusions From China

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-22

    ...Aluminum Extrusions From China AGENCY: United States...less-than-fair-value imports from China of aluminum extrusions...Rubber, Manufacturing, Energy, Allied Industrial and...People's Republic of China: Preliminary...

  7. Current technologies and trends of aluminum design

    E-print Network

    Chen, Michael, 1981-

    2004-01-01

    A literature review of current aluminum technology in the building and construction industry was carried out. Aluminum is an ideal material for building in corrosive environments and for building structures where small ...

  8. Micro Joining of Aluminum Graphite Composites 

    E-print Network

    Velamati, Manasa

    2012-07-16

    Advanced aluminum graphite composites have unique thermal properties due to opposing coefficients of thermal expansion of aluminum and graphite. The thermal and mechanical properties of such composites are anisotropic due to directional properties...

  9. Safe bending of boron/aluminum sheets

    NASA Technical Reports Server (NTRS)

    Liskay, G. G.; Yoshino, S. Y.

    1980-01-01

    Low cost procedure utilizing aluminum backing sheets protects boron/aluminum sheet from cracking during bending. Process utilizes inexpensive universal-brake bending dies rather than special hydroforming dies.

  10. Hermetically sealed aluminum electrolytic capacitor

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S.; Liu, Yanming; Elias, William

    1995-01-01

    Aluminum electrolytic capacitors are presently not allowed on NASA missions because they outgas water and organic vapors, as well as H2. As a consequence, much larger and heavier packages of tantalum capacitors are used. A hermetically sealed aluminum capacitor has been developed under NASA-MSFC SBIR contracts. This capacitor contains a nongassing electrolyte that was developed for this application so internal pressure would remain low. Capacitors rated at 250 to 540 V have been operated under full load for thousands of hours at 85 and 105 C with good electrical performance and low internal pressure. Electrolyte chemistry and seal engineering concepts will be discussed.

  11. Aluminum-carbon composite electrode

    DOEpatents

    Farahmandi, C.J.; Dispennette, J.M.

    1998-07-07

    A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg. 3 figs.

  12. Aluminum-carbon composite electrode

    DOEpatents

    Farahmandi, C. Joseph (Auburn, AL); Dispennette, John M. (Auburn, AL)

    1998-07-07

    A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

  13. 75 FR 70689 - Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum-Greenwood Forge Division; Currently...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-18

    ... in the Federal Register on November 17, 2009 (74 FR 59254). At the request of the State agency and a... and Training Administration Kaiser Aluminum Fabricated Products, LLC; Kaiser Aluminum- Greenwood Forge... Aluminum Fabricated Products, LLC, Kaiser Aluminum-Greenwood Forge Division, including on- site...

  14. DUBLIN CORE

    EPA Science Inventory

    The Dublin Core is a metadata element set intended to facilitate discovery of electronic resources. It was originally conceived for author-generated descriptions of Web resources, and the Dublin Core has attracted broad ranging international and interdisciplinary support. The cha...

  15. Mineral resource of the month: aluminum

    USGS Publications Warehouse

    Bray, E. Lee

    2012-01-01

    The article offers information on aluminum, a mineral resource which is described as the third-most abundant element in Earth's crust. According to the article, aluminum is the second-most used metal. Hans Christian Oersted, a Danish chemist, was the first to isolate aluminum in the laboratory. Aluminum is described as lightweight, corrosion-resistant and an excellent conductor of electricity and heat.

  16. Development of a composite-reinforced aluminum conductor

    SciTech Connect

    Balsam, J.

    1999-11-11

    Fact sheet written for the Inventions and Innovation Program about a new composite-reinforced aluminum conductor for utility transmission and distribution. The millions of people affected by a blackout in the western US, Canada, and parts of Mexico in July 1996 had no idea the power outage was caused by overloaded transmission lines sagging low enough to touch trees. Millions of New Englanders affected by power outages during the 1997--98 winter probably weren't aware that accumulations of ice and snow on transmission lines had caused the lines to snap. Yet, these two examples illustrate the urgent need to begin upgrading this country's aging electrical-power distribution systems. A key step in this process lies in improving the weight and conductivity characteristics of utility transmission and distribution lines. Conventional conductors used for overhead transmission and distribution lines are comprised of aluminum strands of wire wrapped around a steel core. The aluminum serves as the electrical conductor, while the steel provides mechanical support. This hybrid design results in an excellent weight-to-conductivity ratio, but it also yields a heavier product, which requires stronger and more costly support structures and limits conductivity. W. Brandt Goldsworthy and Associates, Inc., of Torrance, California, is developing a new composite-reinforced aluminum conductor to replace aging steel-core lines. The new composite conductor is lighter, stronger, and carries a higher current capacity than traditional power lines. The technology has been designed primarily for domestic utility transmission and distribution systems. This application takes the highest priority as utility deregulation continues to increase the demand for direct-power access. Subsequent applications exist through opportunities in the industrial power, building wire, telecommunications and data transmission, and high-temperature superconductor markets. Similar applications overseas also represent tremendous potential, with growth projected at 10 times that of the United States market.

  17. Blood aluminum levels as a function of aluminum intake from drinking water

    SciTech Connect

    Turnquest, E.M.; Hallenbeck, W.H. )

    1991-04-01

    Questions regarding the health effects of aluminum are still unanswered. The speciation, pharmacokinetics, and toxicity of aluminum are not well understood. Furthermore, no animal or human studies of aluminum absorption have been reported using drinking water as the source of aluminum. The following experiment attempted to reach a better understanding of the bioavailability of aluminum from drinking water. Its objective was to determine whether or not increased aluminum ingestion from drinking water would be reflected in increased serum and whole blood aluminum levels in the baboon experimental model.

  18. PREFACE: Ultrathin layers of graphene, h-BN and other honeycomb structures Ultrathin layers of graphene, h-BN and other honeycomb structures

    NASA Astrophysics Data System (ADS)

    Geber, Thomas; Oshima, Chuhei

    2012-08-01

    Since ancient times, pure carbon materials have been familiar in human society—not only diamonds in jewellery and graphite in pencils, but also charcoal and coal which have been used for centuries as fuel for living and industry. Carbon fibers are stronger, tougher and lighter than steel and increase material efficiency because of their lower weight. Today, carbon fibers and related composite materials are used to make the frames of bicycles, cars and even airplane parts. The two-dimensional allotrope, now called graphene, is just a single layer of carbon atoms, locked together in a strongly bonded honeycomb lattice. In plane, graphene is stiffer than diamond, but out-of-plane it is soft, like rubber. It is virtually invisible, may conduct electricity (heat) better than copper and weighs next to nothing. Carbon compounds with two carbon atoms as a base, such as graphene, graphite or diamond, have isoelectronic sister compounds made of boron-nitrogen pairs: hexagonal and cubic boron nitride, with almost the same lattice constant. Although the two 2D sisters, graphene and h-BN, have the same number of valence electrons, their electronic properties are very different: freestanding h-BN is an insulator, while charge carriers in graphene are highly mobile. The past ten years have seen a great expansion in studies of single-layer and few-layer graphene. This activity has been concerned with the ? electron transport in graphene, in electric and magnetic fields. More than 30 years ago, however, single-layer graphene and h-BN on solid surfaces were widely investigated. It was noted that they drastically changed the chemical reactivity of surfaces, and they were known to 'poison' heterogeneous catalysts, to passivate surfaces, to prevent oxidation of surfaces and to act as surfactants. Also, it was realized that the controlled growth of h-BN and graphene on substrates yields the formation of mismatch driven superstructures with peculiar template functionality on the nanometer scale. This special section contains interesting papers on graphene, h-BN and related 'honeycomb' compounds on solid surfaces, which are currently in development. Interfacial interaction strongly modifies the electronic and atomic structures of these overlayer systems and substrate surfaces. In addition, one can recognize a variety of growth phenomena by changing the surface and growth conditions, which are promising as regards fabricating those noble nanosystems. We have great pleasure in acknowledging the enthusiastic response and participation of our invited authors and their diligent preparation of the manuscripts. Ultrathin layers of graphene, h-BN and other honeycomb structures contents Ultrathin layers of graphene, h-BN and other honeycomb structuresThomas Geber and Chuhei Oshima Templating of arrays of Ru nanoclusters by monolayer graphene/Ru Moirés with different periodicitiesEli Sutter, Bin Wang, Peter Albrecht, Jayeeta Lahiri, Marie-Laure Bocquet and Peter Sutter Controllable p-doping of graphene on Ir(111) by chlorination with FeCl3N A Vinogradov, K A Simonov, A V Generalov, A S Vinogradov, D V Vyalikh, C Laubschat, N Mårtensson and A B Preobrajenski Optimizing long-range order, band gap, and group velocities for graphene on close-packed metal surfacesF D Natterer, S Rusponi, M Papagno, C Carbone and H Brune Epitaxial growth of graphene on transition metal surfaces: chemical vapor deposition versus liquid phase depositionSamuel Grandthyll, Stefan Gsell, Michael Weinl, Matthias Schreck, Stefan Hüfner and Frank Müller High-yield boron nitride nanosheets from 'chemical blowing': towards practical applications in polymer compositesXuebin Wang, Amir Pakdel, Chunyi Zhi, Kentaro Watanabe, Takashi Sekiguchi, Dmitri Golberg and Yoshio Bando BCx layers with honeycomb lattices on an NbB2(0001) surfaceChuhei Oshima Epitaxial growth of boron-doped graphene by thermal decomposition of B4CWataru Norimatsu, Koichiro Hirata, Yuta Yamamoto, Shigeo Arai and Michiko Kusunoki Mechanical exfoliation of epitaxial graphene on Ir(111) enabled by Br2 intercalationCh

  19. 76 FR 23490 - Aluminum tris (O

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-27

    ...aluminum tris (O-ethylphosphonate) on pineapple fodder and forage because they are not...aluminum tris (O-ethylphosphonate) on pineapple fodder and forage because they are...aluminum tris (O-ethylphosphonate) on pineapple fodder and forage because they...

  20. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Aluminum sulfate. 182.1125 Section 182.1125 Food... GENERALLY RECOGNIZED AS SAFE Multiple Purpose GRAS Food Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This substance is generally recognized as safe when used...

  1. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aluminum sulfate. 182.1125 Section 182.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This...

  2. 21 CFR 172.310 - Aluminum nicotinate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aluminum nicotinate. 172.310 Section 172.310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Special Dietary and Nutritional Additives § 172.310 Aluminum nicotinate. Aluminum nicotinate may be...

  3. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Aluminum sulfate. 182.1125 Section 182.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This...

  4. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Aluminum sulfate. 182.1125 Section 182.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This...

  5. Aluminum: Principled Scenario Exploration through Minimality

    E-print Network

    Dougherty, Daniel J.

    Aluminum: Principled Scenario Exploration through Minimality Tim Nelson1, Salman Saghafi1, Daniel J. We present Aluminum, a modification of Alloy that presents only minimal scenarios: those that contain no more than is necessary. Aluminum lets users explore the scenario space by adding to scenarios

  6. 21 CFR 182.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Aluminum sulfate. 182.1125 Section 182.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This...

  7. Aluminum in Superconducting Magnets Robert J. Weggel

    E-print Network

    McDonald, Kirk

    Aluminum in Superconducting Magnets Robert J. Weggel Magnet Optimization Research Engineering is aluminum, either ultrapure, as quenchstabilization matrix metal, and/or alloyed and coldworked and heat for magnets in which the stresses and strains are modest. The strongest aluminum alloy commercially available

  8. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This...

  9. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This...

  10. Behorende bij het proefschrift: Aluminum-Mediated

    E-print Network

    Technische Universiteit Delft

    STELLINGEN Behorende bij het proefschrift: Aluminum-Mediated Selective Solid-Phase Epitaxy of High be formed, it would be possible to achieve an ideally selective aluminum-mediated solid-phase epitaxial (SPE) silicon growth (this thesis, Chapter 2). 2. The downscaling of the junction depth in aluminum

  11. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This...

  12. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This...

  13. 21 CFR 582.1125 - Aluminum sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Aluminum sulfate. 582.1125 Section 582.1125 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1125 Aluminum sulfate. (a) Product. Aluminum sulfate. (b) Conditions of use. This...

  14. 21 CFR 172.310 - Aluminum nicotinate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Aluminum nicotinate. 172.310 Section 172.310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Special Dietary and Nutritional Additives § 172.310 Aluminum nicotinate. Aluminum nicotinate may be...

  15. Aluminum: Principled Scenario Exploration through Minimality

    E-print Network

    Fisler, Kathryn

    Aluminum: Principled Scenario Exploration through Minimality Tim Nelson1, Salman Saghafi1, Daniel J Aluminum, a modification of Alloy that presents only minimal scenarios: those that contain no more than is necessary. Aluminum lets users explore the scenario space by adding to scenarios and backtracking. It also

  16. Shielded Aluminum Flat-Conductor Cable

    NASA Technical Reports Server (NTRS)

    Farina, S.

    1984-01-01

    Thin wiring harness stores compactly. Flat aluminum conductors glued between layers of polyimide. Aluminum shield surrounds insulated conductors. Outer layer polyimide. Aluminum shield reduces flexibility of cable and cable withstand only limited number of repetitions of sharp bending at same spot.

  17. Method for Selective Cleaning of Mold Release from Composite Honeycomb Surfaces

    NASA Technical Reports Server (NTRS)

    Pugel, Diane

    2011-01-01

    Honeycomb structures are commonly employed as load- and force-bearing structures as they are structurally strong and lightweight. Manufacturing processes for heat-molded composite honeycomb structures commence with the placement of pre-impregnated composite layups over metal mandrels. To prevent permanent bonding between the composite layup and the metal mandrels, an agent, known as a mold release agent, is used. Mold release agents allow the molded composite material to be removed from mandrels after a heat-forming process. Without a specific removal process, mold release agents may continue to adhere to the surface of the composite material, thereby affecting the bonding of other materials that may come into contact with the composite surface in later stages of processing A constituent common to commercially available household cleaning agents is employed for the removal of mold release agents common to the manufacturing of heat-formed composite materials. The reliability of the solvent has been proven by the longevity and reliability of commercial household cleaners. At the time of this reporting, no one has attempted using constituent for this purpose. The material to be cleaned is immersed in the solution, vertically removed so that the solution is allowed to drain along cell walls and into a solvent bath, and then placed on a compressed airflow table for drying.

  18. Symplectic analysis of dynamic properties of hexagonal honeycomb sandwich tubes with plateau borders

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Deng, Zichen; Meng, Junmiao; Xu, Xiaojian; Wang, Yan

    2015-09-01

    A new type of hexagonal honeycomb sandwich tube with plateau borders are introduced in this work and the Symplectic analysis with its high computational efficiency and high accuracy is applied to obtain the structural dynamic properties. The effects of material distribution (?) and relative density (?bar) on the dynamic properties of the structure are also studied. Based on the definition of the elastic constants and the homogenization method, the independent elastic constants are obtained. By introducing dual variables and applying the variational principle, the canonical equations of Hamiltonian system are constructed. The precise integration method and extended Wittrick-Williams algorithm are adopted to solve the canonical equations. The dispersion relations of sandwich tubes are obtained, and the effects of material distribution and relative density on the normalized frequencies of the sandwich tubes are investigated. The proposed homogenization method is verified by comparing with other researchers' works. Dispersion relations of the sandwich tubes are obtained. The material distribution parameter and the relative density have significant effects on the dynamic properties of the structures. This work expects to offer new opportunities for the optimal design of metallic honeycomb sandwich tubes and future applications in the engineering sector.

  19. Band gap analysis of star-shaped honeycombs with varied Poisson’s ratio

    NASA Astrophysics Data System (ADS)

    Meng, J.; Deng, Z.; Zhang, K.; Xu, X.; Wen, F.

    2015-09-01

    In this paper, star-shaped honeycombs are analyzed in terms of their equivalent mechanical behaviors and band gap properties. Firstly, by applying Castigliano’s second theorem, the effective Young’s modulus and Poisson’s ratio are derived by an analytical method used in structural mechanics. On the basis of Bloch’s theorem, the dispersion characteristics are then analyzed by the dynamic matrix in conjunction with the Wittrick-Williams (W-W) algorithm. It should be noted that the presented method can form a more simple stiffness and mass matrices of the proposed structures, compared with the traditional finite element (FE) method. Thereafter, the effects of the geometrical parameters on the effective constants and band gaps are investigated and discussed. Numerical results demonstrate that the negative Poisson’s ratio provides an enhanced effective Young’s modulus of the considered honeycombs. Furthermore, the band gap exists in a much lower frequency region with an unchanged summing band gap width when the Poisson’s ratio is in negative values. In general, the work can serve as a guide for the optimal design of cellular structures.

  20. Photoexcited states of the harmonic honeycomb iridate ? -Li2IrO3

    NASA Astrophysics Data System (ADS)

    Hinton, J. P.; Patankar, S.; Thewalt, E.; Ruiz, A.; Lopez, G.; Breznay, N.; Vishwanath, A.; Analytis, J.; Orenstein, J.; Koralek, J. D.; Kimchi, I.

    2015-09-01

    We report equilibrium and nonequilibrium optical measurements on the recently synthesized "harmonic" honeycomb iridate ? -Li2IrO3 (LIO), as well as the layered honeycomb iridate Na2IrO3 (NIO). Using Fourier transform infrared microscopy we performed reflectance measurements on LIO, from which we obtained the optical conductivity below 2 eV. In addition, we measured the photoinduced changed in reflectance ? R , as a function of time t , temperature T , and probe field polarization in both LIO and NIO. In LIO, ? R (t ,T ) is anisotropic and comprises three T -dependent components. Two of these components are related to the onset of magnetic order and the third is related to a photoinduced population of metastable electronic excited states. In NIO, ? R (t ,T ) has a single T -dependent component that is strikingly similar to the electronic excitation component of ? R in LIO. Through analysis and comparison of ? R (t ,T ) for two compounds, we extract information on the onset of magnetic correlations at and above the transition temperature in LIO, the bare spin-flip scattering rate in equilibrium, the lifetime of low-lying quasiparticle excitations, and the polarization dependence of optical transitions that are sensitive to magnetic order.

  1. Carbon honeycomb grids for advanced lead-acid batteries. Part III: Technology scale-up

    NASA Astrophysics Data System (ADS)

    Kirchev, A.; Serra, L.; Dumenil, S.; Brichard, G.; Alias, M.; Jammet, B.; Vinit, L.

    2015-12-01

    The carbon honeycomb grid technology employs new carbon/carbon composites with ordered 3D structure instead of the classic lead-acid battery current collectors. The technology is laboratory scaled up from small size grids corresponding to electrodes with a capacity of 3 Ah to current collectors suitable for assembly of lead-acid batteries covering the majority of the typical lead-acid battery applications. Two series of 150 grids each (one positive and one negative) are manufactured using low-cost lab-scale equipment. They are further subjected to pasting with active materials and the resulting battery plates are assembled in 12 V AGM-VLRA battery mono-blocks for laboratory testing and outdoor demonstration in electric scooter replacing its original VRLAB pack. The obtained results demonstrate that the technology can replace successfully the state of the art negative grids with considerable benefits. The use of the carbon honeycomb grids as positive plate current collectors is limited by the anodic corrosion of the entire structure attacking both the carbon/carbon composite part and the electroplated lead-tin alloy coating.

  2. Featureless and nonfractionalized Mott insulators on the honeycomb lattice at 1/2 site filling

    PubMed Central

    Kimchi, Itamar; Parameswaran, S. A.; Turner, Ari M.; Wang, Fa; Vishwanath, Ashvin

    2013-01-01

    Within the Landau paradigm, phases of matter are distinguished by spontaneous symmetry breaking. Implicit here is the assumption that a completely symmetric state exists: a paramagnet. At zero temperature such quantum featureless insulators may be forbidden, triggering either conventional order or topological order with fractionalized excitations. Such is the case for interacting particles when the particle number per unit cell, f, is not an integer. However, can lattice symmetries forbid featureless insulators even at integer f? An especially relevant case is the honeycomb (graphene) lattice—where free spinless fermions at (the two sites per unit cell mean is half-filling per site) are always metallic. Here we present wave functions for bosons, and a related spin-singlet wave function for spinful electrons, on the honeycomb lattice and demonstrate via quantum to classical mappings that they do form featureless Mott insulators. The construction generalizes to symmorphic lattices at integer f in any dimension. Our results explicitly demonstrate that in this case, despite the absence of a noninteracting insulator at the same filling, lack of order at zero temperature does not imply fractionalization.

  3. Strong coupling approach to Mott transition of massless and massive Dirac fermions on honeycomb lattice

    E-print Network

    Adibi, E

    2015-01-01

    Phase transitions in the Hubbard model and ionic Hubbard model at half-filling on the honeycomb lattice are investigated in the strong coupling perturbation theory which corresponds to an expansion in powers of the hopping $t$ around the atomic limit. Within this formulation we find analytic expressions for the single-particle spectrum, whereby the calculation of the insulating gap is reduced to a simple root finding problem. This enables high precision determination of the insulating gap that does not require any extrapolation procedure. The critical value of Mott transition on the honeycomb lattice is obtained to be $U_c\\approx 2.38 t$. Studying the ionic Hubbard model at the lowest order, we find two insulating states, one with Mott character at large $U$ and another with single-particle gap character at large ionic potential, $\\Delta$. The present approach gives a critical gapless state at $U=2\\Delta$ at lowest order. By systematically improving on the perturbation expansion, the density of states around ...

  4. Removal of alachlor from water by catalyzed ozonation on Cu/Al2O3 honeycomb

    PubMed Central

    2013-01-01

    Background The herbicide alachlor (2-chloro-2?6?-diethyl-N-methoxymethylacetanilide) has been known as a probable human carcinogen, and the MCL (minimum contamination level) for drinking water has been set at 2 ?g L-1. Therefore, the advanced methods for effectively removing it from water are a matter of interest. Catalyzed ozonation is a promising method for refractory organics degradation. Cu/Al2O3 catalyzed ozonation for degrading an endocrine disruptor (alachlor) in water was investigated. Results Experimental results showed that the ozonation of alachlor can be effectively catalyzed and enhanced by Cu/Al2O3-honeycomb. The main intermediate products formed (aliphatic carboxylic acids) were mineralized to a large extent in the catalytic process. Conclusions This study has shown that Cu/Al2O3-honeycomb is a feasible and efficient catalyst in the ozonation of alachlor in water. Less intermediate oxidation product was produced in the catalytic process than in the uncatalytic one. Furthermore, the mineralization of alachlor could be enhanced by increasing the pH of the reaction solution. PMID:23977841

  5. Effect of geometry and microstructure of honeycomb TCP scaffolds on bone regeneration.

    PubMed

    Takabatake, Kiyofumi; Yamachika, Eiki; Tsujigiwa, Hidetsugu; Takeda, Yasushi; Kimura, Mariko; Takagi, Shin; Nagatsuka, Hitoshi; Iida, Seiji

    2014-09-01

    In recent years, artificial biological materials have been commonly used for the treatment of bone tissue defects caused by trauma, tumors, or surgical stress. Although tricalcium phosphate (TCP) is a promising absorbent bone tissue reconstruction biomaterial, it has been reported that its biocompatibility and osteoconductivity depend on its preparation method and sintering temperature. In addition, although it is thought that the microenvironment produced by the extracellular matrix plays an important role in cell growth and differentiation, there have been few studies on how the geometric structure of artificial biological materials affects cells. In the present study, a new honeycomb TCP scaffold containing through-holes with diameters of 300 µm has been developed. The influence of the sintering temperature on the crystal structure and material properties of the honeycomb TCP scaffold was investigated using scanning electron microscopy and X-ray diffraction. Its biocompatibility and osteoconductivity were also evaluated by implantation into experimental animals. It was found that a ?-TCP scaffold sintered at 1200°C exhibited high biocompatibility and osteoconductivity, and when it was loaded with BMP-2, it exhibited both osteoconductivity and osteoinductivity, promoting rapid bone formation in both ectopic and orthotopic areas. It is thus a highly promising bone reconstruction material that is expected to find clinical applications. PMID:24115688

  6. Novel electronic degrees of freedom emerging from symmetry breaking of honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Feng, Ji

    2013-03-01

    Electrons are central to the society-transforming information technologies. The intrinsic degrees of freedom of an electron, namely, its charge and spin, have been extensively explored in electronic and spintronic devices. As we are approaching the limit of device miniaturization, the exploration of novel electronic degrees of freedom, in terms of theoretical development and materials discovery, is of current interest. In this talk, we will focus on two strategies to break the symmetry of a Fermionic honeycomb lattice that lead to novel degrees of freedom of Bloch electrons. The essential idea in these approaches is to lift the isospin degeneracy a honeycomb lattice by introducing contrasting identities (chemical or magnetic) to the two sublattices. The new indices of Bloch electrons will then arise, corresponding to contrasting responses to external fields, such as in optical selectivity and anomalous electronic transport. Using combined computational, theoretical and experimental approaches, we go on to demonstrate that the proposed physics can be realized in real material systems. In particular, our results indicate that monolayer transition metal chalcogenides, such as non-magnetic MoX2 and antiferromagnetic MnPX3 (X = S, Se), can indeed exhibit selective circular dichroism. The associated Berry curvature-supported quantum transport will also be discussed.

  7. Facile Synthesis of Hierarchical Mesoporous Honeycomb-like NiO for Aqueous Asymmetric Supercapacitors.

    PubMed

    Ren, Xiaochuan; Guo, Chunli; Xu, Liqiang; Li, Taotao; Hou, Lifeng; Wei, Yinghui

    2015-09-16

    Three-dimensional (3D) hierarchical nanostructures have been demonstrated as one of the most ideal electrode materials in energy storage systems due to the synergistic combination of the advantages of both nanostructures and microstructures. In this study, the honeycomb-like mesoporous NiO microspheres as promising cathode materials for supercapacitors have been achieved using a hydrothermal reaction, followed by an annealing process. The electrochemical tests demonstrate the highest specific capacitance of 1250 F g(-1) at 1 A g(-1). Even at 5 A g(-1), a specific capacitance of 945 F g(-1) with 88.4% retention after 3500 cycles was obtained. In addition, the 3D porous graphene (reduced graphene oxide, rGO) has been prepared as an anode material for supercapacitors, which displays a good capacitance performance of 302 F g(-1) at 1 A g(-1). An asymmetric supercapacitor has been successfully fabricated based on the honeycomb-like NiO and rGO. The asymmetric supercapacitor achieves a remarkable performance with a specific capacitance of 74.4 F g(-1), an energy density of 23.25 Wh kg(-1), and a power density of 9.3 kW kg(-1), which is able to light up a light-emitting diode. PMID:26301430

  8. Investigation of shape memory alloy honeycombs by means of a micromechanical analysis

    NASA Astrophysics Data System (ADS)

    Freed, Yuval; Aboudi, Jacob; Gilat, Rivka

    2008-07-01

    Shape memory alloy (SMA) honeycombs are promising new smart materials which may be used for light-weight structures, biomedical implants, actuators and active structures. In this study, the behavior of several SMA honeycomb structures is investigated by means of a continuum-based thermomechanically coupled micromechanical analysis. To this end, macroscopic inelastic stress-strain responses of several topologies are investigated, both for pseudoelasticity and for shape memory effect. It was found that the triangular topology exhibits the best performance. In addition, the initial transformation surfaces are presented for all possible combinations of applied in-plane stresses. A special two-phase microstructure that is capable of producing an overall negative coefficient of thermal expansion is suggested and studied. In this configuration, in which one of the phases is a SMA, residual strains are being generated upon recovery. Here, the negative coefficient of thermal expansion appears to be associated with a larger amount of residual strain upon recovery. Furthermore, a two-dimensional SMA re-entrant topology that generates a negative in-plane Poisson's ratio is analyzed, and the effect of the full thermomechanical coupling is examined. Finally, the response of a particular three-dimensional microstructure is studied.

  9. Moving vortex phases, dynamical symmetry breaking, and jamming for vortices in honeycomb pinning arrays

    SciTech Connect

    Reichhardt, Charles; Reichhardt, Cynthia

    2008-01-01

    We show using numerical simulations that vortices in honeycomb pinning arrays can exhibit a remarkable variety of dynamical phases that are distinct from those found for triangular and square pinning arrays. In the honeycomb arrays, it is possible for the interstitial vortices to form dimer or higher n-mer states which have an additional orientational degree of freedom that can lead to the formation of vortex molecular crystals. For filling fractions where dimer states appear, a dynamical symmetry breaking can occur when the dimers flow in one of two possible alignment directions. This leads to transport in the direction transverse to the applied drive. We show that dimerization produces distinct types of moving phases which depend on the direction of the driving force with respect to the pinning lattice symmetry. When the dimers are driven along certain directions, a reorientation of the dimers can produce a jamming phenomenon which results in a strong enhancement in the critical depinning force. The jamming can also cause unusual effects such as an increase in the critical depinning force when the size of the pinning sites is reduced.

  10. Electrochemical properties of honeycomb-like structured HFBI self-organized membranes on HOPG electrodes.

    PubMed

    Yamasaki, Ryota; Takatsuji, Yoshiyuki; Lienemann, Michael; Asakawa, Hitoshi; Fukuma, Takeshi; Linder, Markus; Haruyama, Tetsuya

    2014-11-01

    HFBI (derived from Trichoderma sp.) is a unique structural protein, which forms a self-organized monolayer at both air/water interface and water/solid interfaces in accurate two-dimensional ordered structures. We have taken advantage of the unique functionality of HFBI as a molecular carrier for preparation of ordered molecular phase on solid substrate surfaces. The HFBI molecular carrier can easily form ordered structures; however, the dense molecular layers form an electrochemical barrier between the electrode and solution phase. In this study, the electrochemical properties of HFBI self-organized membrane-covered electrodes were investigated. Wild-type HFBI has balanced positive and negative charges on its surface. Highly oriented pyrolytic graphite (HOPG) electrodes coated with HFBI molecules were investigated electrochemically. To improve the electrochemical properties of this HFBI-coated electrode, the two types of HFBI variants, with oppositely charged surfaces, were prepared genetically. All three types of HFBI-coated HOPG electrode perform electron transfer between the electrode and solution phase through the dense HFBI molecular layer. This is because the HFBI self-organized membrane has a honeycomb-like structure, with penetrating holes. In the cases of HFBI variants, the oppositely charged HFBI membrane phases shown opposite electrochemical behaviors in electrochemical impedance spectroscopy. HFBI is a molecule with a unique structure, and can easily form honeycomb-like structures on solid material surfaces such as electrodes. The molecular membrane phase can be used for electrochemical molecular interfaces. PMID:25454670

  11. CaMn2Sb2: Spin waves on a frustrated antiferromagnetic honeycomb lattice

    DOE PAGESBeta

    McNally, D. E.; Simonson, J. W.; Kistner-Morris, J. J.; Smith, G. J.; Hassinger, J. E.; DeBeer-Schmidt, L.; Kolesnikov, A. I.; Zaliznyak, I.; Aronson, M. C.

    2015-05-22

    We present inelastic neutron scattering measurements of the antiferromagnetic insulator CaMn2Sb2:, which consists of corrugated honeycomb layers of Mn. The dispersion of magnetic excitations has been measured along the H and L directions in reciprocal space, with a maximum excitation energy of ? 24 meV. These excitations are well described by spin waves in a Heisenberg model, including first and second neighbor exchange interactions, J1 and J2, in the Mn plane and also an exchange interaction between planes. The determined ratio J2/J1 ? 1/6 suggests that CaMn2Sb2: is the first example of a compound that lies very close to themore »mean field tricritical point, known for the classical Heisenberg model on the honeycomb lattice, where the N´eel phase and two different spiral phases coexist. The magnitude of the determined exchange interactions reveal a mean field ordering temperature ? 4 times larger than the reported N´eel temperature TN = 85 K, suggesting significant frustration arising from proximity to the tricritical point.« less

  12. Aluminum and its light alloys

    NASA Technical Reports Server (NTRS)

    Merica, Paul D

    1920-01-01

    Report is a summary of research work which has been done here and abroad on the constitution and mechanical properties of the various alloy systems with aluminum. The mechanical properties and compositions of commercial light alloys for casting, forging, or rolling, obtainable in this country are described.

  13. Ballistic impact response of an UHMWPE fiber reinforced laminate encasing of an aluminum-alumina hybrid panel

    E-print Network

    Wadley, Haydn

    -alumina hybrid panel M.R. O'Masta a, *, B.G. Compton b , E.A. Gamble b , F.W. Zok b , V.S. Deshpande c , H composites Sandwich panels Aluminum alloys Alumina A B S T R A C T The impact response of an ultrahigh investigated. The laminate encapsulated an aluminum alloy sand- wich panel whose corrugated core was filled

  14. 24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. A CORE WORKER DISPLAYS THE CORE BOX AND CORES FOR A BRASS GATE VALVE BODY MADE ON A CORE BOX, CA. 1950. - Stockham Pipe & Fittings Company, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  15. Aluminum-induced granulomas in a tattoo

    SciTech Connect

    McFadden, N.; Lyberg, T.; Hensten-Pettersen, A.

    1989-05-01

    A patient who developed localized, granulomatous reactions in a tattoo is described. With the use of scanning electron microscopy and energy dispersive x-ray microanalysis, both aluminum and titanium particles were found in the involved skin sections. Intradermal provocation testing with separate suspensions of aluminum and titanium induced a positive response only in the case of aluminum. Examination by scanning electron microscopy and energy dispersive x-ray microanalysis of the provoked response established aluminum as the only nonorganic element present in the test site tissue. This is the first report of confirmed aluminum-induced, delayed-hypersensitivity granulomas in a tattoo.

  16. Decarbonization process for carbothermically produced aluminum

    DOEpatents

    Bruno, Marshall J.; Carkin, Gerald E.; DeYoung, David H.; Dunlap, Sr., Ronald M.

    2015-06-30

    A method of recovering aluminum is provided. An alloy melt having Al.sub.4C.sub.3 and aluminum is provided. This mixture is cooled and then a sufficient amount of a finely dispersed gas is added to the alloy melt at a temperature of about 700.degree. C. to about 900.degree. C. The aluminum recovered is a decarbonized carbothermically produced aluminum where the step of adding a sufficient amount of the finely dispersed gas effects separation of the aluminum from the Al.sub.4C.sub.3 precipitates by flotation, resulting in two phases with the Al.sub.4C.sub.3 precipitates being the upper layer and the decarbonized aluminum being the lower layer. The aluminum is then recovered from the Al.sub.4C.sub.3 precipitates through decanting.

  17. Dynamic impact response of high-density square honeycombs made of TRIP steel and TRIP matrix composite material

    NASA Astrophysics Data System (ADS)

    Ehinger, D.; Krüger, L.; Krause, S.; Martin, U.; Weigelt, C.; Aneziris, C. G.

    2012-08-01

    Two designs of square-celled metallic honeycomb structures fabricated by a modified extrusion technology based on a powder feedstock were investigated. The strength and ductility of these cellular materials are achieved by an austenitic CrNi (AISI 304) steel matrix particle reinforced by an MgO partially-stabilized zirconia building up their cell wall microstructure. Similar to the mechanical behaviour of the bulk materials, the strengthening mechanism and the martensitic phase transformations in the cell walls are affected by the deformation temperature and the nominal strain rate. The microstructure evolution during quasi-static and dynamic impact compression up to high strain rates of 103 1/s influences the buckling and failure behaviour of the honeycomb structures. In contrast to bending-dominated quasi-isotropic networks like open-celled metal foams, axial compressive loading to the honeycomb's channels causes membrane stretching as well as crushing of the vertical cell node elements and cell walls. The presented honeycomb materials differ geometrically in their cell wall thickness-to-cell size-ratio. Therefore, the failure behaviour is predominantly controlled by global buckling and torsional-flexural buckling, respectively, accompanied by plastic matrix flow and strengthening of the cell wall microstructure.

  18. Aerodynamic performance of conventional and advanced design labyrinth seals with solid-smooth abradable, and honeycomb lands. [gas turbine engines

    NASA Technical Reports Server (NTRS)

    Stocker, H. L.; Cox, D. M.; Holle, G. F.

    1977-01-01

    Labyrinth air seal static and dynamic performance was evaluated using solid, abradable, and honeycomb lands with standard and advanced seal designs. The effects on leakage of land surface roughness, abradable land porosity, rub grooves in abradable lands, and honeycomb land cell size and depth were studied using a standard labyrinth seal. The effects of rotation on the optimum seal knife pitch were also investigated. Selected geometric and aerodynamic parameters for an advanced seal design were evaluated to derive an optimized performance configuration. The rotational energy requirements were also measured to determine the inherent friction and pumping energy absorbed by the various seal knife and land configurations tested in order to properly assess the net seal system performance level. Results indicate that: (1) seal leakage can be significantly affected with honeycomb or abradable lands; (2) rotational energy absorption does not vary significantly with the use of a solid-smooth, an abradable, or a honeycomb land; and (3) optimization of an advanced lab seal design produced a configuration that had leakage 25% below a conventional stepped seal.

  19. A novel isolation curtain to reduce turbine ingress heating and an advanced model for honeycomb labyrinth seals 

    E-print Network

    Choi, Dong Chun

    2006-08-16

    A combination of 3-D and 2-D computational fluid dynamics (CFD) modeling as well as experimental testing of the labyrinth seal with hexagonal honeycomb cells on the stator wall was performed. For the 3-D and 2-D CFD models, ...

  20. Impact resistance and energy absorption of regular and functionally graded hexagonal honeycombs with cell wall material strain hardening

    E-print Network

    Vaziri, Ashkan

    with cell wall material strain hardening D. Mousanezhad a , R. Ghosh a , A. Ajdari b , A.M.S. Hamouda c , H honeycomb Material strain hardening Energy absorption Impact resistance a b s t r a c t This paper highlights the effects of cell wall material strain hardening and density functional gradation (FG) on in

  1. A novel isolation curtain to reduce turbine ingress heating and an advanced model for honeycomb labyrinth seals

    NASA Astrophysics Data System (ADS)

    Choi, Dong Chun

    A combination of 3-D and 2-D computational fluid dynamics (CFD) modeling as well as experimental testing of the labyrinth seal with hexagonal honeycomb cells on the stator wall was performed. For the 3-D and 2-D CFD models, the hexagonal honeycomb structure was modeled using the concept of the baffle (zero-thickness wall) and the simplified 2-D fin, respectively. The 3-D model showed that even a small axial change of the tooth (or honeycomb wall) location, or a small circumferential change of the honeycomb wall location significantly affected the flow patterns and leakage characteristics especially for small tooth tip clearance. Also, the local details of the flow field were investigated. The seven basic procedural steps to develop a 2-D axisymmetric honeycomb labyrinth seal leakage model were shown. Clearly demonstrated for varying test conditions was the 2-D model capability to predict the 3-D honeycomb labyrinth flow that had been measured at different operating conditions from that used in developing the 2-D model. Specifically, the 2-D model showed very close agreement with measurements. In addition, the 2-D model greatly reduced the computer resource requirement needed to obtain a solution of the 3-D honeycomb labyrinth seal leakage. The novel and advanced strategy to reduce the turbine ingress heating, and thus the coolant requirement, by injecting a "coolant isolation curtain" was developed numerically using a 3-D CFD model. The coolant isolation curtain was applied under the nozzle guide vane platform for the forward cavity of a turbine stage. Specifically, the isolation curtain serves to isolate the hot mainstream gas from the turbine outer region. The effect of the geometry change, the outer cavity axial gap clearance, the circumferential location of the injection curtain slot and the injection fluid angle on the ingress heating was investigated. Adding the chamfer to the baseline design gave a similar or higher maximum temperature T*max than did the baseline design without chamfer, but implementation of the injection curtain slot reduced substantially T*max of the outer region. In addition, a more desirable uniform adiabatic wall temperature distribution along the outer rotor and stator surfaces was observed due to the presence of the isolation curtain.

  2. Reactively Deposited Aluminum Oxide and Fluoropolymer Filled Aluminum Oxide Protective Coatings for Polymers

    NASA Technical Reports Server (NTRS)

    Rutledge, Sharon K.; Banks, Bruce A.; Hunt, Jason

    1995-01-01

    Reactive ion beam sputter deposition of aluminum simultaneous with low energy arrival of oxygen ions at the deposition surface enables the formation of highly transparent aluminum oxide films. Thick (12 200 A), adherent, low stress, reactively deposited aluminum oxide films were found to provide some abrasion resistance to polycarbonate substrates. The reactively deposited aluminum oxide films are also slightly more hydrophobic and more transmitting in the UV than aluminum oxide deposited from an aluminum oxide target. Simultaneous reactive sputter deposition of aluminum along with polytetrafluoroethylene (PTFE Teflon) produces fluoropolymer-filled aluminum oxide films which are lower in stress, about the same in transmittance, but more wetting than reactively deposited aluminum oxide films. Deposition properties, processes and potential applications for these coatings will be discussed.

  3. Low-aluminum-content iron-aluminum alloys

    SciTech Connect

    Sikka, V.K.; Baldwin, R.H.; Howell, C.R.

    1993-07-01

    The low room-temperature ductility Fe{sub 3}Al-based alloys is associated with their environmental embrittlement. Reducing the aluminum level from 29 to 16 at % has been found to be an effective method in essentially eliminating the environmental-embrittlement effect and increasing the room-temperature ductility value to over 25%. This paper will present data on alloy compositions, melting, casting and processing methods, and mechanical properties. Plans for future work on these alloys will also be described.

  4. Microstructure and Mechanical Properties of AA1235 Aluminum Foil Stocks Produced Directly from Electrolytic Aluminum Melt

    NASA Astrophysics Data System (ADS)

    Xiong, Hanqing; Yu, Kun; Wen, Li; Yao, Sujuan; Dai, Yilong; Wang, Zhifeng

    2015-09-01

    A new process is developed to obtain high-quality AA1235 aluminum foil stocks and to replace the traditional manufacture process. During the new manufacture process, AA1235 aluminum sheets are twin-roll casted directly through electrolytic aluminum melt (EAM), and subsequently the sheets are processed into aluminum foil stocks by cold rolling and annealing. Microstructure and mechanical properties of the AA1235 aluminum sheets produced through such new process are investigated in each state by optimal microscope, scanning electron microscopy, X-ray diffraction, orientation imaging microscopy, transmission electron microscopy, etc. The results show that compared with the traditional AA1235 aluminum foil stocks produced through re-melted aluminum melt (RAM), the amount of impurities is decreased in the EAM aluminum foil stocks. The EAM aluminum foil stock obtains less ?-FeSiAl5 phases, but more ?-Fe2SiAl8 phases. The elongation of EAM aluminum foil stocks is improved significantly owing to more cubic orientation. Especially, the elongation value of the EAM aluminum foil stocks is approximately 25 pct higher than that of the RAM aluminum foil stocks. As a result, the EAM aluminum foil stocks are at an advantage in increasing the processing performance for the aluminum foils during subsequent processes.

  5. Mercury-Free Dissolution of Aluminum-Based Nuclear Material: From Basic Science to the Plant

    SciTech Connect

    Crooks, W.J. III

    2003-05-14

    Conditions were optimized for the first plant-scale dissolution of an aluminum-containing nuclear material without using mercury as a catalyst. This nuclear material was a homogeneous mixture of plutonium oxide and aluminum metal that had been compounded for use as the core matrix in Mark 42 nuclear fuel. Because this material had later failed plutonium distribution specifications, it was rejected for use in the fabrication of Mark 42 fuel tubes, and was stored at the Savannah River Site (SRS) awaiting disposition. This powder-like material was composed of a mixture of approximately 80 percent aluminum and 11 percent plutonium. Historically, aluminum-clad spent nuclear fuels [13] have been dissolved using a mercuric nitrate catalyst in a nitric acid (HNO3) solution to facilitate the dissolution of the bulk aluminum cladding. Developmental work at SRS indicated that the plutonium oxide/aluminum compounded matrix could be dissolved without mercury. Various mercury-free conditions were studied to evaluate the rate of dissolution of the Mark 42 compact material and to assess the corrosion rate to the stainless steel dissolver. The elimination of mercury from the dissolution process fit with waste minimization and industrial hygiene goals to reduce the use of mercury in the United States. The mercury-free dissolution technology was optimized for Mark 42 compact material in laboratory-scale tests, and successfully implemented at the plant.

  6. Hermetically Sealed Aluminum Electrolytic Capacitor

    NASA Technical Reports Server (NTRS)

    Alwitt, Robert S.; Liu, Yanming; Elias, William

    1996-01-01

    Aluminum electrolytic capacitors are presently not allowed on NASA missions because they outgas water and organic vapors, as well as H2. As a consequence, for some applications, much larger and heavier packages of tantalum capacitors must be used. A hermetically sealed aluminum capacitor has been developed. This contains a nongassing electrolyte that was developed for this application so internal pressure would remain low. Capacitors rated from 250 V to 540 V have been operated under full load for thousands of hours at 85 and 105 C with good electrical performance and absence of gas generation. Electrolyte chemistry and seal engineering will be discussed, as well as the extension of this design concept to lower voltage ratings.

  7. Adhesive bonding of aluminum alloys

    SciTech Connect

    Thrall, E.W.; Shannon, R.W.

    1985-01-01

    The topics concerned with the European chromic acid anodize process, the sealed chromic acid anodize, the phosphoric acid anodize, surface analysis, and adhesive selection are discussed. Consideration is given to epoxy adhesives, elevated-temperature-resistant adhesives, the mechanical properties of adhesives, environmental/durability testing, and coatings. Data on the use of chemical analysis for control, the structural analysis of adhesive-bonded joints, tooling design and inspection, nondestructive inspection, and adhesive-bonded aluminum structure repair are presented.

  8. Sodium-aluminum chloride cells

    SciTech Connect

    Granstaff, S.M. Jr.; Auborn, J.J.; Hooper, A.

    1981-01-01

    Secondary cells using solid electrolytes, with molten sodium anodes and having cathodes composed of sulfur compounds and aluminum chloride have been cycled for over 800 deep cycles on a 2.7 volt plateau at moderate temperatures (150-200/degree/C). At these temperatures and operating in a basic solution, the cells avoid the corrosion problems of other higher temperature or acidic solution sodium-sulfur cells. 14 refs.

  9. Electrically Conductive Anodized Aluminum Surfaces

    NASA Technical Reports Server (NTRS)

    Nguyen, Trung Hung

    2006-01-01

    Anodized aluminum components can be treated to make them sufficiently electrically conductive to suppress discharges of static electricity. The treatment was conceived as a means of preventing static electric discharges on exterior satin-anodized aluminum (SAA) surfaces of spacecraft without adversely affecting the thermal-control/optical properties of the SAA and without need to apply electrically conductive paints, which eventually peel off in the harsh environment of outer space. The treatment can also be used to impart electrical conductivity to anodized housings of computers, medical electronic instruments, telephoneexchange equipment, and other terrestrial electronic equipment vulnerable to electrostatic discharge. The electrical resistivity of a typical anodized aluminum surface layer lies between 10(exp 11) and 10(exp 13) Omega-cm. To suppress electrostatic discharge, it is necessary to reduce the electrical resistivity significantly - preferably to < or = 10(exp 9) Omega-cm. The present treatment does this. The treatment is a direct electrodeposition process in which the outer anodized surface becomes covered and the pores in the surface filled with a transparent, electrically conductive metal oxide nanocomposite. Filling the pores with the nanocomposite reduces the transverse electrical resistivity and, in the original intended outer-space application, the exterior covering portion of the nanocomposite would afford the requisite electrical contact with the outer-space plasma. The electrical resistivity of the nanocomposite can be tailored to a value between 10(exp 7) and 10(exp 12) Omega-cm. Unlike electrically conductive paint, the nanocomposite becomes an integral part of the anodized aluminum substrate, without need for adhesive bonding material and without risk of subsequent peeling. The electrodeposition process is compatible with commercial anodizing production lines. At present, the electronics industry uses expensive, exotic, electrostaticdischarge- suppressing finishes: examples include silver impregnated anodized, black electroless nickel, black chrome, and black copper. In comparison with these competing finishes, the present nanocomposite finishes are expected to cost 50 to 20 percent less and to last longer.

  10. Aluminum-lithium target behavior

    SciTech Connect

    McDonell, W.R.

    1989-10-01

    Information on physical properties and irradiation behavior of aluminum-lithium target alloys employed for the production of tritium in Savannah River reactors has been reviewed to support development of technology for the New Production Reactor (NPR). Phase compositions and microstructures, thermal conductivity, mechanical properties, and constituent diffusion phenomena of the alloys, established in prior site studies, are presented. Irradiation behavior, including distributions of product tritium and helium and related exposure limits due to swelling and cracking of the target alloys is discussed, along with gas release processes occurring during subsequent product recovery operations. The property review supports designation of the aluminum-lithium alloys as ideally well-suited target materials for low-temperature, tritium-producing reactors, demonstrated over 35 years of Savannah River reactor operation. Low temperature irradiation and reaction with lithium in the alloy promotes tritium retention during reactor exposure, and the aluminum provides a matrix from which the product is readily recovered on heating following irradiation. 33 refs., 26 figs., 8 tabs.

  11. Targeted grafting of thermoresponsive polymers from a penetrative honeycomb structure for cell sheet engineering.

    PubMed

    Chen, Shuangshuang; Lu, Xuemin; Zhu, Dandan; Lu, Qinghua

    2015-10-01

    Responsive membranes have been used to construct smart biomaterial interfaces. We report a novel approach to fabricate honeycomb films with a pattern of thermoresponsive polymer, namely poly(N-isopropylacrylamide). The approach was based on a combination of the breath figure method and reversible addition-fragmentation chain transfer. The hybrid film had morphological and chemical patterns resulting in varied wettability and morphology at various stages, as well as high thermo-responsiveness. Enhanced cell adhesion was observed at an incubation temperature of 37 °C, which is above its lower critical solution temperature (LCST). Furthermore, cells could be harvested at temperatures below the LCST without trypsin treatment. The non-invasive characteristics give this membrane potential as a substrate for cell sheet engineering. PMID:26268946

  12. Ru-Ru Dimers in honeycomb-layered Li2RuO3

    NASA Astrophysics Data System (ADS)

    Huang, Fei-Ting; Yang, J. J.; Wang, Y. Z.; Horibe, Y.; Cheong, S.-W.

    2014-03-01

    Dark-field transmission electron microscopy and sub-Å aberration-corrected scanning transmission electron microscopy (STEM) have been used to investigate the local structural properties of Li2RuO3 We found intriguing Ru-Ru dimerization in the Ru honeycomb skeletons associated with the spin-orbital coupling of the 4 d electrons below 540 K. Furthermore, we demonstrated that the Ru-Ru dimers can be delicately broken through various antiphase boundaries and chemical doping. Soliton-like walls in the Ru-Ru dimer lattice are unambiguously observed in real space, and are found to order in a periodic manner for particular situations. The correlation between macroscopic physical properties and local structural distortions in the Li2RuO3 will be discussed in detail.

  13. Magnetic hysteresis, compensation behaviors, and phase diagrams of bilayer honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Ersin, Kantar

    2015-10-01

    Magnetic behaviors of the Ising system with bilayer honeycomb lattice (BHL) structure are studied by using the effective-field theory (EFT) with correlations. The effects of the interaction parameters on the magnetic properties of the system such as the hysteresis and compensation behaviors as well as phase diagrams are investigated. Moreover, when the hysteresis behaviors of the system are examined, single and double hysteresis loops are observed for various values of the interaction parameters. We obtain the L-, Q-, P-, and S-type compensation behaviors in the system. We also observe that the phase diagrams only exhibit the second-order phase transition. Hence, the system does not show the tricritical point (TCP).

  14. Asymptotic behavior for a version of directed percolation on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Chang, Shu-Chiuan; Chen, Lung-Chi

    2015-10-01

    We consider a version of directed bond percolation on the honeycomb lattice as a brick lattice such that vertical edges are directed upward with probability y, and horizontal edges are directed rightward with probabilities x and one in alternate rows. Let ?(M , N) be the probability that there is at least one connected-directed path of occupied edges from (0 , 0) to (M , N) . For each x ?(0 , 1 ] , y ?(0 , 1 ] and aspect ratio ? = M / N fixed, we show that there is a critical value ?c =(1 - x + xy) (1 + x - xy) /(xy2) such that as N ? ?, ?(M , N) is 1, 0 and 1 / 2 for ? >?c, ?

  15. Shock-induced melting of honeycomb-shaped Cu nanofoams: Effects of porosity

    NASA Astrophysics Data System (ADS)

    Zhao, F. P.; Li, B.; Jian, W. R.; Wang, L.; Luo, S. N.

    2015-07-01

    We investigate shock-induced melting in honeycomb-shaped Cu nanofoams with extensive molecular dynamics simulations. A total of ten porosities ( ?) are explored, ranging from 0 to 0.9 at an increment of 0.1. Upon shock compression, void collapse leads to local melting followed by supercooling at low shock strengths. Superheating occurs at ? ? 0.1 . Both supercooling of melts and superheating of solid remnants are transient, and the equilibrated shock states eventually fall on the equilibrium melting curve for partial melting. However, phase equilibrium has not been achieved on the time scale of simulations in supercooled Cu liquid (from completely melted nanofoams). The temperatures for incipient and complete melting are related to porosity via a power law, ( 1 - ? ) k , and approach the melting temperature at zero pressure as ? ? 1 .

  16. Strain induced topological phase transitions in monolayer honeycomb structures of group-V binary compounds

    PubMed Central

    Nie, Yaozhuang; Rahman, Mavlanjan; Wang, Daowei; Wang, Can; Guo, Guanghua

    2015-01-01

    We present first-principles calculations of electronic structures of a class of two-dimensional (2D) honeycomb structures of group-V binary compounds. Our results show these new 2D materials are stable semiconductors with direct or indirect band gaps. The band gap can be tuned by applying lattice strain. During their stretchable regime, they all exhibit metal-indirect gap semiconductor-direct gap semiconductor-topological insulator (TI) transitions with increasing strain from negative (compressive) to positive (tensile) values. The topological phase transition results from the band inversion at the ? point which is due to the evolution of bonding and anti-bonding states under lattice strain. PMID:26656257

  17. Nano-honeycomb structured transparent electrode for enhanced light extraction from organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Shi, Xiao-Bo; Qian, Min; Wang, Zhao-Kui; Liao, Liang-Sheng

    2015-06-01

    A universal nano-sphere lithography method has been developed to fabricate nano-structured transparent electrode, such as indium tin oxide (ITO), for light extraction from organic light-emitting diodes (OLEDs). Perforated SiO2 film made from a monolayer colloidal crystal of polystyrene spheres and tetraethyl orthosilicate sol-gel is used as a template. Ordered nano-honeycomb pits on the ITO electrode surface are obtained by chemical etching. The proposed method can be utilized to form large-area nano-structured ITO electrode. More than two folds' enhancement in both current efficiency and power efficiency has been achieved in a red phosphorescent OLED which was fabricated on the nano-structured ITO substrate.

  18. Growth of Si nanorods in honeycomb and hexagonal-closed-packed arrays using glancing angle deposition

    SciTech Connect

    Patzig, Christian; Rauschenbach, Bernd; Fuhrmann, Bodo; Leipner, Hartmut S.

    2008-01-15

    Regular arrays of Si nanorods with a circular cross section in hexagonal-closed-packed and triangular cross section in honeycomblike arrangements were grown using glancing angle deposition on Si(100) and fused silica substrates that were patterned with Au dots using self-assembled mono- and double layers of polystyrene nanospheres as an evaporation mask. The Au dots were used as an etching mask for the underlying silica substrates in a reactive ion beam etching process, which greatly enhanced the height of the seeding spaces for the subsequent glancing angle deposition. An elongated shadowing length l of the prepatterned nucleation sites and less growth of Si structures between the surface mounds could be achieved this way. Differences in form, height, and diameter of the Si nanorods grown on either hcp or honeycomb arrays are explained by purely geometrical arguments. Different seed heights and interseed distances are found to be the main reasons for the strong distinctions between the grown nanorod arrays.

  19. Absence of a Spin Liquid Phase in the Hubbard Model on the Honeycomb Lattice

    PubMed Central

    Sorella, Sandro; Yunoki, Seiji

    2012-01-01

    A spin liquid is a novel quantum state of matter with no conventional order parameter where a finite charge gap exists even though the band theory would predict metallic behavior. Finding a stable spin liquid in two or higher spatial dimensions is one of the most challenging and debated issues in condensed matter physics. Very recently, it has been reported that a model of graphene, i.e., the Hubbard model on the honeycomb lattice, can show a spin liquid ground state in a wide region of the phase diagram, between a semi-metal (SM) and an antiferromagnetic insulator (AFMI). Here, by performing numerically exact quantum Monte Carlo simulations, we extend the previous study to much larger clusters (containing up to 2592 sites), and find, if any, a very weak evidence of this spin liquid region. Instead, our calculations strongly indicate a direct and continuous quantum phase transition between SM and AFMI. PMID:23251778

  20. CO2 Adsorption on Activated Carbon Honeycomb-Monoliths: A Comparison of Langmuir and Tóth Models

    PubMed Central

    Vargas, Diana P.; Giraldo, Liliana; Moreno-Piraján, Juan C.

    2012-01-01

    Activated carbon honeycomb-monoliths with different textural properties were prepared by chemical activation of African palm shells with H3PO4, ZnCl2 and CaCl2 aqueous solutions of various concentrations. The adsorbents obtained were characterized by N2 adsorption at 77 K, and their carbon dioxide adsorption capacities were measured at 273 K and 1 Bar in volumetric adsorption equipment. The experimental adsorption isotherms were fitted to Langmuir and Tóth models, and a better fit was observed to Tóth equation with a correlation coefficient of 0.999. The maximum experimental values for adsorption capacity at the highest pressure (2.627–5.756 mmol·g?1) are between the calculated data in the two models. PMID:22942710

  1. Nine new phosphorene polymorphs with non-honeycomb structures: a much extended family.

    PubMed

    Wu, Menghao; Fu, Huahua; Zhou, Ling; Yao, Kailun; Zeng, Xiao Cheng

    2015-05-13

    We predict a new class of monolayer phosphorus allotropes, namely, ?-P, ?-P, ?-P, and ?-P. Distinctly different from the monolayer ?-P (black) and previously predicted ?-P (Phys. Rev. Lett. 2014, 112, 176802), ?-P, and ?-P (Phys. Rev. Lett. 2014, 113, 046804) with buckled honeycomb lattice, the new allotropes are composed of P4 square or P5 pentagon units that favor tricoordination for P atoms. The new four polymorphs, together with five additional hybrid polymorphs, greatly enrich the phosphorene structures, and their stabilities are confirmed by first-principles calculations. In particular, the ?-P is shown to be equally stable as the ?-P (black) and more stable than all previously reported phosphorene polymorphs. Prediction of nonvolatile ferroelastic switching and structural transformation among different polymorphs under strains points out their potential applications via strain engineering. PMID:25844524

  2. Zigzag order and phase competition in expanded Kitaev-Heisenberg model on honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Yao, Xiaoyan

    2015-07-01

    The Kitaev-Heisenberg model on the honeycomb lattice is investigated in two cases: (I) with the Kitaev interaction between the nearest neighbors, and (II) with the Kitaev interaction between the next nearest neighbors. In the full parameter range, the ground states are searched by Monte Carlo simulation and identified by evaluating the correlation functions. The energies of different phases are calculated and compared with the simulated result to show the phase competition. It is observed from both energy calculation and the density of states that the zigzag order shows a symmetric behavior to the stripy phase in the pure Kitaev-Heisenberg model. By considering more interactions in both cases, the energy of zigzag order can be reduced lower than the energies of other states. Thus the zigzag phase may be stabilized in more parameter region and even extended to the whole parameter range.

  3. Resonant Transmission of Air-Coupled Ultrasound Through Metallic Inserts in Honeycomb Sandwich Structures

    SciTech Connect

    Peters, J.J.; Barnard, D.J.; Hsu, D.K.; Dayal, V.

    2005-04-09

    Metallic inserts are embedded into composite honeycomb sandwiches as hard points for mechanical connections. Air-coupled ultrasound can be used for detecting disbonds between the insert and the facesheet. It was discovered in such inspections that a surprisingly large amplitude could be transmitted through thick metallic inserts (e.g. 0.75'' thick and 1.5'' diameter), whereas a thin plate of the same material will transmit a much weaker signal. This paper reports an experimental and analytic study of the geometrical effect of inserts on transmitted UT signals. Modal analyses of cylindrical inserts were made using the finite element code ANSYS. The transmission efficiency or air-coupled ultrasound correlated well with the longitudinal vibration mode of the cylinder.

  4. Time resolved shearographic and thermographic NDE methods for graphite epoxy/honeycomb composite

    SciTech Connect

    Spicer, J.B.; Champion, J.L.; Osiander, R.; Spicer, J.W.M.

    1996-10-01

    Results are presented showing the application of both time resolved thermography and time resolved shearography to specimens of graphite epoxy/honeycomb composites containing delaminations. Of particular importance is the demonstration that the depth of a defect can be determined by measuring the time dependence of the shearographic fringe development during heating. Upon application of a noncontacting heating source, large thermoelastic deformation in the heated region occurs over delamination regions in a specimen. The bending stresses in the material above the delamination decrease characteristically when the diffusing temperature field interacts with the delamination and the temperature gradient through the intact material decreases. As a result, both the presence of the delamination and its depth can be measured simultaneously.

  5. Strain induced topological phase transitions in monolayer honeycomb structures of group-V binary compounds.

    PubMed

    Nie, Yaozhuang; Rahman, Mavlanjan; Wang, Daowei; Wang, Can; Guo, Guanghua

    2015-01-01

    We present first-principles calculations of electronic structures of a class of two-dimensional (2D) honeycomb structures of group-V binary compounds. Our results show these new 2D materials are stable semiconductors with direct or indirect band gaps. The band gap can be tuned by applying lattice strain. During their stretchable regime, they all exhibit metal-indirect gap semiconductor-direct gap semiconductor-topological insulator (TI) transitions with increasing strain from negative (compressive) to positive (tensile) values. The topological phase transition results from the band inversion at the ? point which is due to the evolution of bonding and anti-bonding states under lattice strain. PMID:26656257

  6. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus_minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus_minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  7. Aluminum oxide film thickness and emittance

    SciTech Connect

    Thomas, J.K.; Ondrejcin, R.S.

    1991-11-01

    Aluminum reactor components which are not actively cooled could be subjected to high temperatures due to gamma heating after the core coolant level dropped during the ECS phase of a hypothetical LOCA event. Radiative heat transfer is the dominant heat transfer process in this scenario and therefore the emittance of these components is of interest. Of particular interest are the safety rod thimbles and Mark 60B blanket assemblies; for the K Reactor, these components have been exposed to low temperature (< 55{degrees}C) moderator for about a year. The average moderator temperature was assumed to be 30{degrees}C. The Al oxide film thickness at this temperature, after one year of exposure, is predicted to be 6.4 {mu}m {plus minus} 10%; insensitive to exposure time. Dehydration of the film during the gamma heating accident would result in a film thickness of 6.0 {mu}m {plus minus} 11%. Total hemispherical emittance is predicted to be 0.69 at 96{degrees}C, decreasing to 0.45 at 600{degrees}C. Some phenomena which would tend to yield thicker oxide films in the reactor environment relative to those obtained under experimental conditions were neglected and the predicted film thickness values are therefore conservative. The emittance values predicted for a given film thickness are also conservative. The conservativisms inherent in the predicted emittance are particularly relevant for uncertainty analysis of temperatures generated using these values.

  8. Chiral d-wave superconductivity on the honeycomb lattice close to the Mott state

    NASA Astrophysics Data System (ADS)

    Black-Schaffer, Annica M.; Wu, Wei; Le Hur, Karyn

    2014-08-01

    We study superconductivity on the honeycomb lattice close to the Mott state at half filling. Due to the sixfold lattice symmetry and disjoint Fermi surfaces at opposite momenta, we show that several different fully gapped superconducting states naturally exist on the honeycomb lattice, of which the chiral d +id'-wave state has previously been shown to appear when superconductivity appears close to the Mott state. Using renormalized mean-field theory to study the t-J model and quantum Monte Carlo calculations of the Hubbard-U model we show that the d +id'-wave state is the favored superconducting state for a wide range of on-site repulsion U, from the intermediate to the strong coupling regime. We also investigate the possibility of a mixed chirality d-wave state, where the overall chirality cancels. We find that a state with d +id'-wave symmetry in one valley but d -id'-wave symmetry in the other valley is not possible in the t-J model without reducing the translational symmetry, due to the zero-momentum and spin-singlet nature of the superconducting order parameter. Moreover, any extended unit cells result either in disjoint Dirac points, which cannot harbor this mixed chirality state, or the two valleys are degenerate at the zone center, where valley hybridization prevents different superconducting condensates. We also investigate extended unit cells where the overall chirality cancels in real space. For supercells containing up to eight sites, including the Kekulé distortion, we find no energetically favorable d-wave solution with an overall zero chirality within the restriction of the t-J model.

  9. Automated laser-based barely visible impact damage detection in honeycomb sandwich composite structures

    SciTech Connect

    Girolamo, D. Yuan, F. G.; Girolamo, L.

    2015-03-31

    Nondestructive evaluation (NDE) for detection and quantification of damage in composite materials is fundamental in the assessment of the overall structural integrity of modern aerospace systems. Conventional NDE systems have been extensively used to detect the location and size of damages by propagating ultrasonic waves normal to the surface. However they usually require physical contact with the structure and are time consuming and labor intensive. An automated, contactless laser ultrasonic imaging system for barely visible impact damage (BVID) detection in advanced composite structures has been developed to overcome these limitations. Lamb waves are generated by a Q-switched Nd:YAG laser, raster scanned by a set of galvano-mirrors over the damaged area. The out-of-plane vibrations are measured through a laser Doppler Vibrometer (LDV) that is stationary at a point on the corner of the grid. The ultrasonic wave field of the scanned area is reconstructed in polar coordinates and analyzed for high resolution characterization of impact damage in the composite honeycomb panel. Two methodologies are used for ultrasonic wave-field analysis: scattered wave field analysis (SWA) and standing wave energy analysis (SWEA) in the frequency domain. The SWA is employed for processing the wave field and estimate spatially dependent wavenumber values, related to discontinuities in the structural domain. The SWEA algorithm extracts standing waves trapped within damaged areas and, by studying the spectrum of the standing wave field, returns high fidelity damage imaging. While the SWA can be used to locate the impact damage in the honeycomb panel, the SWEA produces damage images in good agreement with X-ray computed tomographic (X-ray CT) scans. The results obtained prove that the laser-based nondestructive system is an effective alternative to overcome limitations of conventional NDI technologies.

  10. Automated laser-based barely visible impact damage detection in honeycomb sandwich composite structures

    NASA Astrophysics Data System (ADS)

    Girolamo, D.; Girolamo, L.; Yuan, F. G.

    2015-03-01

    Nondestructive evaluation (NDE) for detection and quantification of damage in composite materials is fundamental in the assessment of the overall structural integrity of modern aerospace systems. Conventional NDE systems have been extensively used to detect the location and size of damages by propagating ultrasonic waves normal to the surface. However they usually require physical contact with the structure and are time consuming and labor intensive. An automated, contactless laser ultrasonic imaging system for barely visible impact damage (BVID) detection in advanced composite structures has been developed to overcome these limitations. Lamb waves are generated by a Q-switched Nd:YAG laser, raster scanned by a set of galvano-mirrors over the damaged area. The out-of-plane vibrations are measured through a laser Doppler Vibrometer (LDV) that is stationary at a point on the corner of the grid. The ultrasonic wave field of the scanned area is reconstructed in polar coordinates and analyzed for high resolution characterization of impact damage in the composite honeycomb panel. Two methodologies are used for ultrasonic wave-field analysis: scattered wave field analysis (SWA) and standing wave energy analysis (SWEA) in the frequency domain. The SWA is employed for processing the wave field and estimate spatially dependent wavenumber values, related to discontinuities in the structural domain. The SWEA algorithm extracts standing waves trapped within damaged areas and, by studying the spectrum of the standing wave field, returns high fidelity damage imaging. While the SWA can be used to locate the impact damage in the honeycomb panel, the SWEA produces damage images in good agreement with X-ray computed tomographic (X-ray CT) scans. The results obtained prove that the laser-based nondestructive system is an effective alternative to overcome limitations of conventional NDI technologies.

  11. Aluminum Waste Reaction Indicators in a Municipal Solid Waste Landfill

    E-print Network

    Aluminum Waste Reaction Indicators in a Municipal Solid Waste Landfill Timothy D. Stark, F.ASCE1 landfills may contain aluminum from residential and commercial solid waste, industrial waste, and aluminum pro- duction wastes. Some aluminum-bearing waste materials, particularly aluminum production wastes

  12. Core Algebra.

    ERIC Educational Resources Information Center

    Hawaii Univ., Honolulu. Curriculum Research and Development Group.

    This document focuses on Core Algebra, a course offered in the Hawaii State Department of Education's "Mathematics Program Guide." This algebra option is designed to be less theoretical and more application-oriented than Algebra IA and IB. The text opens with a list of twenty minimum learner objectives of the course. The next section presents an…

  13. Test versus predictions for rotordynamic and leakage characteristics of a convergent-tapered, honeycomb-stator/smooth-rotor annular gas seal 

    E-print Network

    Van Der Velde Alvarez, Daniel Eduardo

    2009-05-15

    This thesis presents the results for measured and predicted rotordynamic coefficients and leakage for a convergent-tapered honeycomb seal (CTHC). The test seals had a diameter of 114.968 mm (4.5263 in) at the entrance, and ...

  14. Effects of low fluence neutron bombardment on material properties of aluminum 2024 t-3 and aluminum wire

    NASA Astrophysics Data System (ADS)

    Reeves, Jesse Lee

    The purpose of this work was to explore the impact of neutron irradiation (1018 n/m2 to 1021 n/m 2) on the aluminum alloy 2024 T-3, and several corrosion resistant treatments commonly used. The irradiation was conducted in the Utah Nuclear Engineering Programs Reactor facility using the Fast Neutron Irradiation Facility (FNIF) with a 1 MeV equivalent beam and the Center Irradiator (CI) with average neutron energy of 0.58 MeV. Historically, materials tests have focused on mechanical failures occurring at very high fluence. These same tests have generally been conducted for pure materials: the limited research existing for alloyed materials focuses on power plant materials such as zircaloy and steel. This body of information is mainly used to avoid catastrophic performance failures. Small research and test reactors operating at low power will subject core materials to fluence from 1014 n/m2 to 1024 n/m2. Aluminum alloys are very common in these systems. Materials used in research reactors, such as aluminum, have been deemed adequate due to high radiation tolerance and low mechanical failure rates. While aluminum and its alloys are a well-defined set of materials in nonradiation environments, there are very little published data for them for low fluence neutron radiation. This work measured Al 2024's (T-3) thermal conductivity, electrical resistivity, oxide layer thickness, oxide/metal interface and corrosion resistance (using passive current density) for Alodine, Anodize type II, Anodize type III and native oxide. These measurements were taken before and after irradiation and results were examined. Over the course of 30 to 50 years, property changes will likely impact thermal diffusion, corrosion properties and electrical properties. Defining these changes may give future engineers the tools needed to safely justify life extensions and build inspection methods to identify pre-failure conditions.

  15. Aluminum-stabilized NB3SN superconductor

    DOEpatents

    Scanlan, Ronald M. (Livermore, CA)

    1988-01-01

    An aluminum-stabilized Nb.sub.3 Sn superconductor and process for producing same, utilizing ultrapure aluminum. Ductile components are co-drawn with aluminum to produce a conductor suitable for winding magnets. After winding, the conductor is heated to convert it to the brittle Nb.sub.3 Sn superconductor phase, using a temperature high enough to perform the transformation but still below the melting point of the aluminum. This results in reaction of substantially all of the niobium, while providing stabilization and react-in-place features which are beneficial in the fabrication of magnets utilizing superconducting materials.

  16. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 25 2013-07-01 2013-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  17. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  18. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  19. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  20. 40 CFR 180.1091 - Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false Aluminum isopropoxide and aluminum... PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1091 Aluminum isopropoxide and aluminum secondary butoxide; exemption from the requirement of a tolerance. Aluminum isopropoxide (CAS Reg. No....

  1. Nanosized aluminum altered immune function.

    PubMed

    Braydich-Stolle, Laura K; Speshock, Janice L; Castle, Alicia; Smith, Marcus; Murdock, Richard C; Hussain, Saber M

    2010-07-27

    On the basis of their uses in jet fuels and munitions, the most likely scenario for aluminum nanoparticle (NP) exposure is inhalation. NPs have been shown to be capable of penetrating deep into the alveolar regions of the lung, and therefore human alveolar macrophages (U937) with human type II pneumocytes (A549) were cultured together and exposed to NPs dispersed in an artificial lung surfactant to more accurately mimic the lung microenvironment. Two types of NPs were evaluated: aluminum (Al) and aluminum oxide (Al2O3). Following a 24-h incubation, cell viability was assessed using MTS, and mild toxicity was observed at higher doses with the U937 cells affected more than the A549. Since the U937 cells provided protection from NP toxicity, the cocultures were exposed to a benign concentration of NPs and infected with the respiratory pathogen community-associated methicillin-resistant Staphylococcus aureus (ca-MRSA) to determine any changes in cellular function. Phagocytosis assays demonstrated that the NPs impaired phagocytic function, and bacterial growth curves confirmed that this reduction in phagocytosis was not related to NP-bacteria interactions. Furthermore, NFkappaB PCR arrays and an IL-6 and TNF-alpha real time PCR demonstrated that both types of NPs altered immune response activation. This change was confirmed by ELISA assays that evaluated the secretion of IL-6, IL-8, IL-10, IL-1beta, and TNF-alpha and illustrated that the NPs repressed secretion of these cytokines. Therefore, although the NPs were not toxic to the cells, they did impair the cell's natural ability to respond to a respiratory pathogen regardless of NP composition. PMID:20593840

  2. Irradiation tests for U 3Si-Al dispersion fuels with aluminum cladding

    NASA Astrophysics Data System (ADS)

    Chae, H. T.; Kim, H.; Lee, C. S.; Jun, B. J.; Park, J. M.; Kim, C. K.; Sohn, D. S.

    2008-02-01

    The HANARO fuel element is made of a cylindrical fuel meat, top and bottom aluminum end plugs and an aluminum cladding with eight longitudinal fins. The fuel meat of each fuel element consists of a dispersion of small particles of a high density uranium silicide (U 3Si) compound in a continuous aluminum matrix. To verify the irradiation performance of the HANARO fuel at a high power and a high burnup, in-pile irradiation tests were performed in the HANARO core. Detailed non-destructive and destructive post-irradiation examinations were conducted. It was verified through the irradiation tests that the HANARO fuel maintains a proper in-pile performance and integrity even at a high power of 121 kW/m and up to a high burnup of 85 at.% U-235.

  3. Potassium alum and aluminum sulfate micro-inclusions in polar ice from Dome Fuji, East Antarctica

    NASA Astrophysics Data System (ADS)

    Ohno, Hiroshi; Iizuka, Yoshinori; Horikawa, Shinichiro; Sakurai, Toshimitsu; Hondoh, Takeo; Motoyama, Hideaki

    2014-03-01

    Water-soluble trace constituents affect the physicochemical properties of polar ice. Their structural distribution provides important insights into the formation history of ice and inclusions. We report the first finding of KAl(SO4)2·12H2O (potassium alum) and Al2(SO4)3·nH2O (aluminum sulfate) micro-inclusions in the Dome Fuji ice core, East Antartica, using a micro-Raman technique. Eutectic temperatures of these water-soluble species determined using thermal analysis were -0.4 °C for potassium alum and -8.0 °C for aluminum sulfate. Although the formation process of the aluminum-bearing sulfates remains unclear, the occurrence of these salts largely depends on ice depth.

  4. 21 CFR 582.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Aluminum potassium sulfate. 582.1129 Section 582.1129...Food Additives § 582.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  5. 21 CFR 182.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Aluminum potassium sulfate. 182.1129 Section 182.1129...Food Substances § 182.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  6. 21 CFR 182.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Aluminum potassium sulfate. 182.1129 Section 182.1129...Food Substances § 182.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  7. 21 CFR 182.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Aluminum potassium sulfate. 182.1129 Section 182.1129...Food Substances § 182.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  8. 21 CFR 582.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Aluminum potassium sulfate. 582.1129 Section 582.1129...Food Additives § 582.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  9. 21 CFR 182.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Aluminum potassium sulfate. 182.1129 Section 182.1129...Food Substances § 182.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  10. 21 CFR 582.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Aluminum potassium sulfate. 582.1129 Section 582.1129...Food Additives § 582.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  11. 21 CFR 182.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2009-04-01 true Aluminum potassium sulfate. 182.1129 Section 182.1129...Food Substances § 182.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  12. 21 CFR 582.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Aluminum potassium sulfate. 582.1129 Section 582.1129...Food Additives § 582.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  13. 21 CFR 582.1129 - Aluminum potassium sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Aluminum potassium sulfate. 582.1129 Section 582.1129...Food Additives § 582.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of use....

  14. 49 CFR 229.51 - Aluminum main reservoirs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...2012-10-01 2012-10-01 false Aluminum main reservoirs. 229.51 Section 229.51 Transportation... Brake System § 229.51 Aluminum main reservoirs. (a) Aluminum main reservoirs used on locomotives shall be designed...

  15. 49 CFR 229.51 - Aluminum main reservoirs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...2013-10-01 2013-10-01 false Aluminum main reservoirs. 229.51 Section 229.51 Transportation... Brake System § 229.51 Aluminum main reservoirs. (a) Aluminum main reservoirs used on locomotives shall be designed...

  16. 49 CFR 229.51 - Aluminum main reservoirs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...2014-10-01 2014-10-01 false Aluminum main reservoirs. 229.51 Section 229.51 Transportation... Brake System § 229.51 Aluminum main reservoirs. (a) Aluminum main reservoirs used on locomotives shall be designed...

  17. 21 CFR 182.1781 - Sodium aluminum phosphate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 2014-04-01 2014-04-01 false Sodium aluminum phosphate. 182.1781 Section...Purpose GRAS Food Substances § 182.1781 Sodium aluminum phosphate. (a) Product. Sodium aluminum phosphate. (b) Conditions...

  18. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2009-04-01 true Aluminum calcium silicate. 182.2122 Section 182.2122...Anticaking Agents § 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  19. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122...Anticaking Agents § 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...

  20. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122...Anticaking Agents § 582.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2...