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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. Buckling of Aluminum Honeycomb Core and Its Effect on Ultrasonic Velocity

    NASA Astrophysics Data System (ADS)

    Hsu, David K.; Dayal, Vinay; Harris, Aaron L.; Peters, John J.

    2004-02-01

    This paper reports an investigation on the interior buckling morphology of impact-damaged honeycomb core and its effects on the amplitude and velocity of transmitted ultrasound. In a systematic experiment, honeycomb core specimens were compressed to various degrees of buckling and the transmitted ultrasonic amplitude and time-of-flight were measured as a function of percent deformation. The measured time-of-flight showed a dramatic increase with increasing degree of buckling. As a comparison, the time of flight was modeled in a transient finite element analysis of a buckled honeycomb cell wall. A single cycle load was applied to the top end of the simplified model and the response was recorded at the bottom end of the wall. The finite element simulation results for time-of-flight showed qualitative agreement with the experimental data.

  3. Prospects of pulse phase thermography for finding disbonds in CFRP-sandwich parts with aluminum honeycomb cores compared to ultrasonic

    NASA Astrophysics Data System (ADS)

    Gruber, J.; Stotter, B.; Mayr, G.; Hendorfer, G.

    2013-01-01

    This work shows the prospects of pulse phase thermography (PPT) compared to ultrasonic testing when applied to carbon fiber reinforced polymer (CFRP) sandwich parts with aluminum honeycomb cores. Measurements were carried out on full-scale components with flaws like disbonds, septum disbonds, staggers and displaced cores, where the last two are not literally flaws, but nevertheless regions of interest. The effect of the measurement time and the feasibility of extrapolating temperature decays were evaluated. Phase images, gathered with PPT, are compared with ultrasonic Cscan images to show the capability of PPT for quality assurance purposes. Finally, the saving on inspection time when using pulse phase thermography instead of ultrasonic testing is considered.

  4. Aluminum core structures brazed without use of flux

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Aluminum alloy face sheets are brazed to aluminum alloy honeycomb cores without using corrosive flux by means of one or three methods. The completed brazed structure has the high-strength characteristics of heat treated aluminum alloys.

  5. Experimental Analysis and Modeling of the Crushing of Honeycomb Cores

    NASA Astrophysics Data System (ADS)

    Aminanda, Y.; Castanié, B.; Barrau, J.-J.; Thevenet, P.

    2005-05-01

    In the aeronautical field, sandwich structures are widely used for secondary structures like flaps or landing gear doors. The modeling of low velocity/low energy impact, which can lead to a decrease of the structure strength by 50%, remains a designer’s main problem. Since this type of impact has the same effect as quasi-static indentation, the study focuses on the behavior of honeycomb cores under compression. The crushing phenomenon has been well identified for years but its mechanism is not described explicitly and the model proposed may not satisfy industrial purposes. To understand the crushing mechanism, honeycomb test specimens made of Nomex™, aluminum alloy and paper were tested. During the crushing, a CCD camera showed that the cell walls buckled very quickly. The peak load recorded during tests corresponded to the buckling of the common edge of three honeycomb cells. Further tests on corner structures to simulate only one vertical edge of a honeycomb cell show a similar behavior. The different specimens exhibited similar load/displacement curves and the differences observed were only due to the behavior of the different materials. As a conclusion of this phenomenological study, the hypothesis that loads are mainly taken by the vertical edge can be made. So, a honeycomb core subjected to compression can be modeled by a grid of nonlinear springs. A simple analytical model was then developed and validated by tests on Nomex™ honeycomb core indented by different sized spherical indenters. A good correlation between theory and experiment was found. This result can be used to satisfactorily model using finite elements the indentation on a sandwich structure with a metallic or composite skin and honeycomb core.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    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.

  8. The Total Hemispheric Emissivity of Painted Aluminum Honeycomb at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    NASA uses high-emissivity surfaces on deep-space radiators or 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. 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.

  10. Adhesive coating eliminated in new honeycomb-core fabrication process

    NASA Technical Reports Server (NTRS)

    Batty, W. L.; Hayes, R. H.; Magee, F. S.

    1974-01-01

    Technique eliminates use of silicone-based adhesive material as bonding medium. Adhesive requires precise time-temperature cure. Prepreg resin is used as bonding medium, and each layer is laminated together to form honeycomb billet. Process can be used in any application where nonmetallic honeycomb core is being fabricated.

  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. 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.

  13. 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...

  14. 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...

  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. 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...

  18. Finite Element Development and Specifications of a Patched, Recessed Nomex Core Honeycomb Panel for Increased Sound Transmission Loss

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.

    2007-01-01

    This informal report summarizes the development and the design specifications of a recessed nomex core honeycomb panel in fulfillment of the deliverable in Task Order 13RBE, Revision 10, Subtask 17. The honeycomb panel, with 0.020-inch thick aluminum face sheets, has 0.016-inch thick aluminum patches applied to twenty-five, 6 by 6 inch, quarter inch thick recessed cores. A 10 dB higher transmission loss over the frequency range 250 - 1000 Hz was predicted by a MSC/NASTRAN finite element model when compared with the transmission loss of the base nomex core honeycomb panel. The static displacement, due to a unit force applied at either the core or recessed core area, was of the same order of magnitude as the static displacement of the base honeycomb panel when exposed to the same unit force. The mass of the new honeycomb design is 5.1% more than the base honeycomb panel. A physical model was constructed and is being tested.

  19. Crushing Strength of Aluminum Honeycomb with Thinning Cell Wall

    NASA Astrophysics Data System (ADS)

    Ogasawara, Nagahisa; Chiba, Norimasa; Kobayashi, Eiji; Kikuchi, Yuji

    To evaluate the crash safety of automobiles, various collision tests are performed by the auto industry. In the offset frontal collision test and the side collision test, the target is an aluminum honeycomb material which has thinning cell walls. In this study, based on the analyses of the shock absorption mechanism, a new crushing strength formula is proposed. First, load-displacement curves obtained from compression tests in quasi-static condition showed an almost linear relation between a thinning rate of cell walls and a crushing strength. Second, based on Wierzbicki's theory, a new formula was proposed, which can estimate a crushing strength of a honeycomb material with thinning wall. In addition, a correcting equation which considered an elastic deformation was also proposed. Third, parametric analyses were carried out with a FE model which can simulate a delamination between cell walls. The results obtained from the theory and FEM almost corresponded to each other for a wide range of the thinning rate. Fourth, impact tests were carried out, in which the weight was dropped freely at the speed used for the automobile tests. Those results almost agreed well with the sum of the theoretical crush strength and the inside air pressure.

  20. Glass polyimide honeycomb cores for advanced space transportation systems

    NASA Technical Reports Server (NTRS)

    Brentjes, J.

    1979-01-01

    The use of a glass fiber reinforced polyimide honeycomb was considered for various applications requiring lightweight stiff structures which may experience temperatures up to 600K. The experiences and results of fabricating these core types are reported. The process parameters and most desirable characteristics are noted. The differences in considering resins for making laminates versus their use in surface coatings are stressed. This comparison is made to explain the problems encountered in using the three new resin types for dipping honeycomb to the desired density. Some properties and the effect of post cure, forming and ventilating techniques for the condensation polyimide core types are presented.

  1. Apparatus measures thermal conductivity of honeycomb-core panels

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Overall thermal conductivity of honeycomb-core panels at elevated temperatures is measured by an apparatus with a heater assembly and a calibrated heat-rate transducer. The apparatus has space between the heater and transducer for insertion of a test panel and insulation.

  2. 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.

  3. Probabilistic nondestructive evaluation of bonded aluminum honeycomb structures

    NASA Astrophysics Data System (ADS)

    Schaefer, Lloyd A.

    1995-07-01

    Aluminum honeycomb panels fabricated in accordance with spacecraft fracture control guidelines must be evaluated to a 90/95 POD/CL (probability of detection/confidence) level for detection of the critical initial flaw (CIF) size. Severe weight limitations can drive the CIF to a size of one cell diameter, or smaller. Additionally, producibility (low or no type II errors) must be maintained, and inspection costs minimized. To assure these goals, a reliability demonstration program was undertaken on thin skin panels for the Space Station Electric Power System ORU (orbital replacement unit) enclosures. This paper examines the probabilistic NDE process in detail, including: analysis of the manufacturing methodology, expected flaw types, construction of the disbond flaw data base, and the subsequent evaluations and results using laser shearography. The experimental data is then reduced utilizing the statistical methodology outlined in a proposed military standard for NDE reliability demonstrations, and contrasted against conventional through transmission ultrasonic inspection. The effort revealed that substantial gains in system reliability and flaw type discrimination are possible with laser shearography, along with a nearly order of magnitude reduction in inspection time.

  4. 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.

  5. Smart impact management devices: experimental validation of impact triggered rapid expansion of aluminum honeycomb

    NASA Astrophysics Data System (ADS)

    Browne, Alan L.; Johnson, Nancy L.; Webb, Scott R.

    2006-03-01

    A major limitation of current dedicated impact energy management structures and passive devices used in the transportation industry is that their starting volume is their maximum volume, i.e. they dissipate energy by crushing or stroking from a larger to a smaller volume. This space so occupied is not available for other uses, including such necessary/desirable functions as vehicle serviceability and repair, operational clearances, and interior spaciousness. This limitation has led to the proposal of a class of "smart" impact energy management devices, based on unexpanded aluminum honeycomb (HOBE), that initially occupy a small volume and based on sensor input are rapidly expanded to a much larger crushable volume (nominally 75 times greater) just prior to or in response to an impact. This paper documents the first portion of an experimental exploration of the viability of this technology. Specific goals of the herein documented test program were the demonstration, starting from blocks of unexpanded aluminum honeycomb, a) of the feasibility (and robustness) of sensor triggered rapid expansion both in terms of the integrity and uniformity of the resulting expanded honeycomb, and b) that expansion mechanisms that were required could be simple and have low energy/force requirements. The test program documented here was successful in both respects, demonstrating and thus validating the feasibility and robustness of low energy rapid expansion of aluminum honeycomb.

  6. 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.

  7. 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.

  8. Prospects and limitations of digital Shearography and Active Thermography in finding and rating flaws in CFRP sandwich parts with honeycomb core

    NASA Astrophysics Data System (ADS)

    Gruber, J.; Mayr, G.; Hendorfer, G.

    2012-05-01

    This work shows the prospects and limitations of the non-destructive testing methods Digital Shearography and Active Thermography when applied to CFRP sandwich parts with honeycomb cores. Two specimens with different core materials (aluminum, NOMEX) and artificial flaws such as delaminations, disbonds and inclusions of foreign material, are tested with Digital Shearography and Pulse Thermography including Pulse Phase Thermography. Both methods provide a good ability for finding and rating the flaws.

  9. 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%.

  10. 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.

  11. Quiet Honeycomb Panels

    NASA Technical Reports Server (NTRS)

    Palumbo, Daniel L.; Klos, Jacob

    2010-01-01

    Sandwich honeycomb composite panels are lightweight and strong, and, therefore, provide a reasonable alternative to the aluminum ring frame/stringer architecture currently used for most aircraft airframes. The drawback to honeycomb panels is that they radiate noise into the aircraft cabin veil- efficiently provoking the need for additional sound treatment which adds weight and reduces the material's cost advantage. A series of honeycomb panels was made -hick incorporated different design strategies aimed at reducing the honeycomb panels' radiation efficiency while at the same time maintaining their strength. The majority of the designs were centered around the concept of creating 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.

  12. Modal analysis and acoustic transmission through offset-core honeycomb sandwich panels

    NASA Astrophysics Data System (ADS)

    Mathias, Adam Dustin

    The work presented in this thesis is motivated by an earlier research that showed that double, offset-core honeycomb sandwich panels increased thermal resistance and, hence, decreased heat transfer through the panels. This result lead to the hypothesis that these panels could be used for acoustic insulation. Using commercial finite element modeling software, COMSOL Multiphysics, the acoustical properties, specifically the transmission loss across a variety of offset-core honeycomb sandwich panels, is studied for the case of a plane acoustic wave impacting the panel at normal incidence. The transmission loss results are compared with those of single-core honeycomb panels with the same cell sizes. The fundamental frequencies of the panels are also computed in an attempt to better understand the vibrational modes of these particular sandwich-structured panels. To ensure that the finite element analysis software is adequate for the task at hand, two relevant benchmark problems are solved and compared with theory. Results from these benchmark results compared well to those obtained from theory. Transmission loss results from the offset-core honeycomb sandwich panels show increased transmission loss, especially for large cell honeycombs when compared to single-core honeycomb panels.

  13. 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

    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.

  14. Shape-variable sandwich structure with SMA honeycomb core and CFRP skins

    NASA Astrophysics Data System (ADS)

    Okabe, Yoji; Sugiyama, Hiroshi

    2009-03-01

    The authors proposed a sandwich structure that consists of a shape memory alloy (SMA) honeycomb core and carbon fiber reinforced plastic (CFRP) skins as a lightweight geometric-variable structure. This method has the better ability to bend skins with high in-plane stiffness, because the SMA honeycomb core generates a recovery-shear-force and applies the force uniformly to the skins. Hence, although this sandwich beam is really lightweight and has a moderate specific bending stiffness, the beam can be bent by raising the temperature. The honeycomb core was made of thin Ti-Ni SMA foils, and skins were thin unidirectional CFRP laminates. Pre-shear-strain was applied to the SMA honeycomb core, and the both ends of the two skins were fixed. When the beam was heated, it was bent upward taking the form of a sigmoid curve. Furthermore, it was verified that the beam was able to generate the sufficient actuation force. Then, when the specimen was cooled down to the room temperature, the specimen returned to the straight beam again. Hence the twoway actuation is possible by heating and cooling. Also the mechanism of this bending deformation could be clarified by a numerical simulation using the finite element method.

  15. 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.

  16. 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.

  17. 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.

  18. Complex foamed aluminum parts as permanent cores in aluminum castings

    SciTech Connect

    Simancik, F.; Schoerghuber, F.

    1998-12-31

    The feasibility of complex shaped aluminum foam parts as permanent cores in aluminum castings has been investigated. The foamed samples were prepared by injection of the foam into sand molds. It turned out that sound castings can be produced if the foam core is properly preheated and/or surface treated before casting. The effect of the foam core on the performance of the casting was evaluated by in compression testing and by measuring structural damping. The gain in the related properties turned out to be much higher than the weight increase of the casting due to the presence of the core. The weight increase may be partially offset through a reduction of the wall-thickness of the shell.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Guided wave propagation in a honeycomb composite sandwich structure in presence of a high density core.

    PubMed

    Sikdar, Shirsendu; Banerjee, Sauvik

    2016-09-01

    A coordinated theoretical, numerical and experimental study is carried out in an effort to interpret the characteristics of propagating guided Lamb wave modes in presence of a high-density (HD) core region in a honeycomb composite sandwich structure (HCSS). Initially, a two-dimensional (2D) semi-analytical model based on the global matrix method is used to study the response and dispersion characteristics of the HCSS with a soft core. Due to the complex structural characteristics, the study of guided wave (GW) propagation in HCSS with HD-core region inherently poses many challenges. Therefore, a numerical simulation of GW propagation in the HCSS with and without the HD-core region is carried out, using surface-bonded piezoelectric wafer transducer (PWT) network. From the numerical results, it is observed that the presence of HD-core significantly decreases both the group velocity and the amplitude of the received GW signal. Laboratory experiments are then conducted in order to verify the theoretical and numerical results. A good agreement between the theoretical, numerical and experimental results is observed in all the cases studied. An extensive parametric study is also carried out for a range of HD-core sizes and densities in order to study the effect due to the change in size and density of the HD zone on the characteristics of propagating GW modes. It is found that the amplitudes and group velocities of the GW modes decrease with the increase in HD-core width and density. PMID:27290650

  7. Phase diagram of dipolar hard-core bosons on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Nakafuji, Takashi; Ito, Takeshi; Nagamori, Yuya; Ichinose, Ikuo

    2016-08-01

    In this paper, we study phase diagrams of dipolar hard-core boson gases on a honeycomb lattice. The system is described by the Haldane-Bose-Hubbard model with complex hopping amplitudes and nearest-neighbor repulsion. By using the slave-particle representation of the hard-core bosons and also the path-integral quantum Monte Carlo simulations, we investigate the system and show that the systems have a rich phase diagram. There are Mott, superfluid, chiral superfluid, and sublattice chiral superfluid phases as well as the density-wave phase. We also found a coexisting phase of superfluid and chiral superfluid. Critical behaviors of the phase transitions are also clarified.

  8. Honeycomb-laminate composite structure

    NASA Technical Reports Server (NTRS)

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

    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.

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

    NASA Technical Reports Server (NTRS)

    Rinker, Martin; Krueger, Ronald; Ratcliffe, James

    2013-01-01

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

  10. Phononic band gap design in honeycomb lattice with combinations of auxetic and conventional core

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    We present a novel design of a honeycomb lattice geometry that uses a seamless combination of conventional and auxetic cores, i.e. elements showing positive and negative Poisson’s ratio. The design is aimed at tuning and improving the band structure of periodic cellular structures. The proposed cellular configurations show a significantly wide band gap at much lower frequencies compared to their pure counterparts, while still retaining their major dynamic features. Different topologies involving both auxetic inclusions in a conventional lattice and conversely hexagonal cellular inclusions in auxetic butterfly lattices are presented. For all these cases the impact of the varying degree of auxeticity on the band structure is evaluated. The proposed cellular designs may offer significant advantages in tuning high-frequency bandgap behaviour, which is relevant to phononics applications. The configurations shown in this paper may be made iso-volumetric and iso-weight to a given regular hexagonal topology, making possible to adapt the hybrid lattices to existing sandwich structures with fixed dimensions and weights. This work also features a comparative study of the wave speeds corresponding to different configurations vis-a vis those of a regular honeycomb to highlight the superior behaviour of the combined hybrid lattice.

  11. Electromechanical modeling of a honeycomb core integrated vibration energy converter with increased specific power for energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Chandrasekharan, Nataraj

    especially if the application imposes a space/size constraint. Moreover, the bimorph with increased thickness will now require a larger mechanical force to deform the structure which can fall outside the input ambient excitation amplitude range. In contrast, the honeycomb core bimorph offers an advantage in terms of preserving the global geometric dimensions. The natural frequency of the honeycomb core bimorph can be altered by manipulating honeycomb cell design parameters, such as cell angle, cell wall thickness, vertical cell height and inclined cell length. This results in a change in the mass and stiffness properties of the substrate and hence the bimorph, thereby altering the natural frequency of the harvester. Design flexibility of honeycomb core bimorphs is demonstrated by varying honeycomb cell parameters to alter mass and stiffness properties for power harvesting. The influence of honeycomb cell parameters on power generation is examined to evaluate optimum design to attain highest specific power. In addition, the more compliant nature of a honeycomb core bimorph decreases susceptibility towards fatigue and can increase the operating lifetime of the harvester. The second component of this dissertation analyses an uncoupled equivalent circuit model for piezoelectric energy harvesting. Open circuit voltage developed on the piezoelectric materials can be easily computed either through analytical or finite element models. The efficacy of a method to determine power developed across a resistive load, by representing the coupled piezoelectric electromechanical problem with an external load as an open circuit voltage driven equivalent circuit, is evaluated. The lack of backward feedback at finite resistive loads resulting from such an equivalent representation is examined by comparing the equivalent circuit model to the governing equations of a fully coupled circuit model for the electromechanical problem. It is found that the backward feedback is insignificant for weakly

  12. 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%.

  13. Light-weight sandwich panel honeycomb core with hybrid carbon-glass fiber composite skin for electric vehicle application

    NASA Astrophysics Data System (ADS)

    Cahyono, Sukmaji Indro; Widodo, Angit; Anwar, Miftahul; Diharjo, Kuncoro; Triyono, Teguh; Hapid, A.; Kaleg, S.

    2016-03-01

    The carbon fiber reinforced plastic (CFRP) composite is relative high cost material in current manufacturing process of electric vehicle body structure. Sandwich panels consisting polypropylene (PP) honeycomb core with hybrid carbon-glass fiber composite skin were investigated. The aim of present paper was evaluate the flexural properties and bending rigidity of various volume fraction carbon-glass fiber composite skins with the honeycomb core. The flexural properties and cost of panels were compared to the reported values of solid hybrid Carbon/Glass FRP used for the frame body structure of electric vehicle. The finite element model of represented sandwich panel was established to characterize the flexural properties of material using homogenization technique. Finally, simplified model was employed to crashworthiness analysis for engine hood of the body electric vehicle structure. The good cost-electiveness of honeycomb core with hybrid carbon-glass fiber skin has the potential to be used as a light-weight alternative material in body electric vehicle fabricated.

  14. 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.

  15. 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.

  16. Insulated Honeycomb

    NASA Technical Reports Server (NTRS)

    Bhat, Balakrishna T.

    1989-01-01

    Proposed insulated honeycomb structure similar to reinforced honeycomb structure described in NPO-17538. Panels of insulated honeycomb used to make supports for solar-energy collectors and radar antennas.

  17. 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.

  18. Wax Reinforces Honeycomb During Machining

    NASA Technical Reports Server (NTRS)

    Towell, Timothy W.; Fahringer, David T.; Vasquez, Peter; Scheidegger, Alan P.

    1995-01-01

    Method of machining on conventional metal lathe devised for precise cutting of axisymmetric contours on honeycomb cores made of composite (matrix/fiber) materials. Wax filling reinforces honeycomb walls against bending and tearing while honeycomb being contoured on lathe. Innovative method of machining on lathe involves preparation in which honeycomb is placed in appropriate fixture and the fixture is then filled with molten water-soluble wax. Number of different commercial waxes have been tried.

  19. Debris Impact on CFRP-AL Honeycomb Sandwich Structure

    NASA Astrophysics Data System (ADS)

    Higashide, Masumi; Nagao, Yosuke; Kibe, Seishiro; Francesconi, Alessandro; Paverin, Daniele

    In order to do risk assessments of debris impacts on unmanned spacecraft, it is necessary to investigate damage of honeycomb sandwich structures caused by debris impacts. However, the study of the honeycomb sandwich panel with CFRP face sheets has not been sufficiently performed. The purpose of this study is to investigate hypervelocity impact phenomena of CFRP-AL honeycomb sandwich structure. Hypervelocity impact tests were performed with a two-stage light gas gun at University of Padova. Three kinds of CFRP-AL honeycomb sandwich panels which are frequently used as a material of a spacecraft structure were tested. The cell size and the core thickness were varied. Aluminum spheres, 0.8 mm in diameter, were used as projectiles. The tests were performed at a velocity range between 2 and 5 km/sec. After the tests, the projectiles perforated all targets. The perforation holes on the panels were measured, and ultrasonic inspection was performed. The area of the perforation holes of the panel were increased with the impact velocity. The core size of the honeycomb core did not influence the relationship between the hole and the impact velocity. Impacts of the projectile on the foil of honeycomb cell caused heavy damage to a face sheet of the opposite side of the impact surface.

  20. 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.

  1. Honeycomb vs. Foam: Evaluating Potential Upgrades to ISS Module Shielding

    NASA Technical Reports Server (NTRS)

    Ryan, Shannon J.; Christiansen, Eric L.

    2009-01-01

    The presence of honeycomb cells in a dual-wall structure is advantageous for mechanical performance and low weight in spacecraft primary structures but detrimental for shielding against impact of micrometeoroid and orbital debris particles (MMOD). The presence of honeycomb cell walls acts to restrict the expansion of projectile and bumper fragments, resulting in the impact of a more concentrated (and thus lethal) fragment cloud upon the shield rear wall. The Multipurpose Laboratory Module (MLM) is a Russian research module scheduled for launch and ISS assembly in 2011 (currently under review). Baseline shielding of the MLM is expected to be predominantly similar to that of the existing Functional Energy Block (FGB), utilizing a baseline triple wall configuration with honeycomb sandwich panels for the dual bumpers and a thick monolithic aluminum pressure wall. The MLM module is to be docked to the nadir port of the Zvezda service module and, as such, is subject to higher debris flux than the FGB module (which is aligned along the ISS flight vector). Without upgrades to inherited shielding, the MLM penetration risk is expected to be significantly higher than that of the FGB module. Open-cell foam represents a promising alternative to honeycomb as a sandwich panel core material in spacecraft primary structures as it provides comparable mechanical performance with a minimal increase in weight while avoiding structural features (i.e. channeling cells) detrimental to MMOD shielding performance. In this study, the effect of replacing honeycomb sandwich panel structures with metallic open-cell foam structures on MMOD shielding performance is assessed for an MLM-representative configuration. A number of hypervelocity impact tests have been performed on both the baseline honeycomb configuration and upgraded foam configuration, and differences in target damage, failure limits, and derived ballistic limit equations are discussed.

  2. Processing and characterization of honeycomb composite systems

    NASA Astrophysics Data System (ADS)

    Shafizadeh, Jahan Emir

    Honeycomb composite structures are widely used in the aerospace and sporting goods industries because of the superior performance and weight saving advantages they offer over traditional metal structures. However, in order to maximize the mechanical and chemical properties of honeycomb composites, the structures must be specially designed to take advantage of their inherent anisotropic, viscoelastic and heterogeneous qualities. In the open literature little work has been done to understand these relationships. Most research efforts have been focused towards studying and modeling the effects of environmental exposure, impact damage and energy absorption. The objectives of this work was to use a systemic engineering approach to explore the fundamental material relationships of honeycomb composites with an emphasis towards the industrial manufacturing, design and performance characteristics of these materials. To reach this goal, a methodology was created to develop model honeycomb systems that were characteristically similar to their commercial counterparts. From the model systems, some of the important chemical and mechanical properties that controlled the behavior of honeycomb core were identified. With the knowledge gained from the model system, studies were carried out to correlate the compressive properties of honeycomb rings to honeycomb core. This type of correlation gives paper, resin, and adhesive manufactures the ability to develop new honeycomb materials without requiring specific honeycomb manufacturers to divulge their trade secrets. After characterizing the honeycomb core, efforts were made to understand the manufacturing and in-service responses of honeycomb materials. Using three Design of Experiments, investigations were performed to measure the mechanisms of composite structures to propagate damage and water over a fourteen month service period. Collectively, this research represents a fundamental starting point for understanding the processing

  3. 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

  4. 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

  5. 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.

  6. The use of neutron imaging for the study of honeycomb structures in aircraft

    NASA Astrophysics Data System (ADS)

    Hungler, P. C.; Bennett, L. G. I.; Lewis, W. J.; Brenizer, J. S.; Heller, A. K.

    2009-06-01

    Highly maneuverable aircraft, such as the CF188 Hornet, have several flight control surfaces on both the leading and the trailing edges of the wing surfaces. They are composed of composite panels constructed of aluminum honeycomb core usually covered with graphite epoxy skins. Although very light and structurally stiff, they are being compromised by water ingress. The trapped water degrades their structural integrity by interacting with the adhesive. Various studies are underway to understand the movement of water in the honeycomb core as well as to determine a method of removing the water. With a vertical neutron beam tube at Royal Military College (RMC), the component can be positioned horizontally and the pooled water in each honeycomb cell can be imaged. These images have been compared with those from a horizontal beam and thus vertical placement of the structure at the Pennsylvania State University Radiation Science and Engineer Center's Breazeale reactor. Thereby, both the filet bond between the honeycomb and the skin as well as the node bond between the honeycomb cells can be studied to determine their contribution to the movement of water throughout the structure. Moreover, the exit path for water has been visualized as part of developing a drying procedure for these flight control surfaces.

  7. Titanium honeycomb panel testing

    NASA Astrophysics Data System (ADS)

    Richards, W. L.; Thompson, Randolph C.

    The paper describes the procedures of thermal mechanical tests carried out at the NASA Dryden Flight Research Facility on two tianium honeycomb wing panels bonded using liquid interface diffusion (LID) technique, and presents the results of these tests. The 58.4 cm square panels consisted of two 0.152-cm-thick Ti 6-2-4-2 face sheets LID-bonded to a 1.9-cm-thick honeycomb core, with bearing plates fastened to the perimeter of the upper and the lower panel surfaces. The panels were instrumented with sensors for measuring surface temperature, strain, and deflections to 315 C and 482 C. Thermal stress levels representative of those encountered during aerodynamic heating were produced by heating the upper panel surface and restraining all four edges. After more than 100 thermal cycles from room temperature to 315 C and 50 cycles from room temperature to 482 C, no significant structural degradation was detected in the panels.

  8. Titanium honeycomb panel testing

    NASA Technical Reports Server (NTRS)

    Richards, W. L.; Thompson, Randolph C.

    1991-01-01

    The paper describes the procedures of thermal mechanical tests carried out at the NASA Dryden Flight Research Facility on two tianium honeycomb wing panels bonded using liquid interface diffusion (LID) technique, and presents the results of these tests. The 58.4 cm square panels consisted of two 0.152-cm-thick Ti 6-2-4-2 face sheets LID-bonded to a 1.9-cm-thick honeycomb core, with bearing plates fastened to the perimeter of the upper and the lower panel surfaces. The panels were instrumented with sensors for measuring surface temperature, strain, and deflections to 315 C and 482 C. Thermal stress levels representative of those encountered during aerodynamic heating were produced by heating the upper panel surface and restraining all four edges. After more than 100 thermal cycles from room temperature to 315 C and 50 cycles from room temperature to 482 C, no significant structural degradation was detected in the panels.

  9. Face Sheet/Core Disbond Growth in Honeycomb Sandwich Panels Subjected to Ground-Air-Ground Pressurization and In-Plane Loading

    NASA Technical Reports Server (NTRS)

    Chen, Zhi M.; Krueger, Ronald; Rinker, Martin

    2015-01-01

    Typical damage modes in light honeycomb sandwich structures include face sheet/core disbonding and core fracture, both of which can pose a threat to the structural integrity of a component. These damage modes are of particular interest to aviation certification authorities since several in-service occurrences, such as rudder structural failure and other control surface malfunctions, have been attributed to face sheet/core disbonding. Extensive studies have shown that face sheet/core disbonding and core fracture can lead to damage propagation caused by internal pressure changes in the core. The increasing use of composite sandwich construction in aircraft applications makes it vitally important to understand the effect of ground-air-ground (GAG) cycles and conditions such as maneuver and gust loads on face sheet/core disbonding. The objective of the present study was to use a fracture mechanics based approach developed earlier to evaluate the loading at the disbond front caused by ground-air-ground pressurization and in-plane loading. A honeycomb sandwich panel containing a circular disbond at one face sheet/core interface was modeled with three-dimensional (3D) solid finite elements. The disbond was modeled as a discrete discontinuity and the strain energy release rate along the disbond front was computed using the Virtual Crack Closure Technique (VCCT). 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. The commercial finite element analysis software, Abaqus/Standard, was used for the analyses. The recursive pressure-deformation coupling problem was solved by representing the entrapped air in the honeycomb cells as filled cavities in Abaqus/Standard. The results show that disbond size, face sheet thickness and core thickness are important parameters that determine crack tip loading at the disbond front. Further, the pressure

  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. Lightweight Aluminum Mirrors Using Foam Core Sandwich Construction

    NASA Technical Reports Server (NTRS)

    Content, D.; Lyons, J., III; Budinoff, J.

    1999-01-01

    The possible use of all aluminum mirrors made from thin faceplates supported by aluminum foam is explored from an optomechanical design and fabrication perspective. Foam mirrors can be relatively cheaply and easily made using conventional foam fabrication and diamond turning; such a mirror recently flew for the first time on the Stardust mission. The proposed structural concept is highly weight efficient and should not be prone to quilting. The weight and structural stability of such mirrors is presented, along with plans underway at GSFC for developing this concept.

  12. A preliminary report on the effect of elevated temperature exposure on the mechanical properties of titanium-alloy honeycomb-core sandwich panels.

    NASA Technical Reports Server (NTRS)

    Bales, T. T.; Cain, R. L.

    1971-01-01

    A study has been initiated to determine the effects of elevated-temperature exposure on the room-temperature mechanical properties of titanium honeycomb-core sandwich panels fabricated by brazing or spot diffusion bonding. Only flatwise tensile properties following exposure have been determined to date. Preliminary results indicate very little change in the flatwise tensile strength of sandwich panels fabricated by spot diffusion bonding following exposures of 10,000 hr at 600 and 800 F and 1000 hr at 1000 F. Titanium panels fabricated by using a Ti-Zr-Be braze alloy are susceptible to oxidation at elevated temperature and experience flatwise tensile strength degradation after continuous exposures of 7500 hr at 600 F, 1000 hr at 800 F, and less than 100 hr at 1000 F. It is possible that the exposure life of the brazed panels may be substantially increased if the panel edges are sealed to prevent oxidation of the braze alloy.

  13. Honeycomb-Fin Heat Sink

    NASA Technical Reports Server (NTRS)

    Rippel, Wally E.

    1989-01-01

    Improved finned heat sink for electronic components more lightweight, inexpensive, and efficient. Designed for use with forced air, easily scaled up to dissipate power up to few hundred watts. Fins are internal walls of aluminum honeycomb structure. Cell structure gives strength to thin aluminum foil. Length of channels chosen for thermodynamic efficency; columns of cells combined in any reasonable number because flowing air distributed to all. Heat sink cools nearly as effectively at ends as near its center, no matter how many columns of cells combined.

  14. Nonlinear acoustics and honeycomb materials

    NASA Astrophysics Data System (ADS)

    Thompson, D. O.

    2012-05-01

    The scope of research activity that Bruce Thompson embraced was very large. In this talk three different research topics that the author shared with Bruce are reviewed. They represent Bruce's introduction to NDE and include nonlinear acoustics, nondestructive measurements of adhesive bond strengths in honeycomb panels, and studies of flexural wave dispersion in honeycomb materials. In the first of these, four harmonics of a 30 Mhz finite amplitude wave were measured for both fused silica and aluminum single crystals with varying lengths and amounts of cold work using a capacity microphone with heterodyne receiver with a flat frequency response from 30 to 250 Mhz. The results for fused silica with no dislocation structure could be described by a model due to Fubini, originally developed for gases, that depends upon only the second and third order elastic constants and not the fourth and higher order constants. The same was not true for the aluminum with dislocation structures. These results raised some questions about models for harmonic generation in materials with dislocations. In the second topic, experiments were made to determine the adhesive bond strengths of honeycomb panels using the vibrational response of the panels (Chladni figures). The results showed that both the damping characteristics of panel vibrations as a whole and velocity of propagation of elastic waves that travel along the surface and sample the bondline can be correlated with destructively determined bond strengths. Finally, the phase velocity of flexural waves traveling along a 1-inch honeycomb sandwich panel was determined from 170 Hz to 50 Khz, ranging from 2.2×104 cm/sec at the low end to 1.18×105 cm/sec at 40 Khz. The dispersion arises from the finite thickness of the panel and agreed with the results of continuum models for the honeycomb. Above 40 Khz, this was not the case. The paper concludes with a tribute to Bruce for his many wonderful contributions and lessons beyond his

  15. Ambient temperature fatigue tests of elements of an actively cooled honeycomb sandwich structural panel

    NASA Technical Reports Server (NTRS)

    Sharpe, E. L.; Elber, W.

    1977-01-01

    Elements of an actively cooled structural panel for a hypersonic aircraft have been investigated for fatigue characteristics. The study involved a bonded honeycomb sandwich panel with d-shaped coolant tubes. The curved portion of these tubes was embedded in the honeycomb, and the flat portion was bonded or soldered to the inner surface of the outer skin. The elements examined were two plain skin specimens (aluminum alloy); two specimens with skins attached to manifolds and tubes (one specimen was bonded, the other soldered); and a specimen representative of a corner section of the complete cooled sandwich. Sinusoidal loads were applied to all specimens. The honeycomb sandwich specimen was loaded in both tension and compression; the other specimens were loaded in tension only. The cooling tubes were pressurized with oil throughout the fatigue tests. The most significant results of these tests follow: All specimens exceeded their design life of 20,000 cycles without damage. Crack growth rates obtained in the plain skin specimens were used to determine the crack growth characteristics of aluminum alloy. Cracks in skins either bonded or soldered to cooling tubes propagated past the tubes without penetration. The coolant tubes served as crack arresters and temporarily stopped crack growth when a crack reached a tube-skin interface. The honeycomb core demonstrated that it could contain leakage from a tube.

  16. Post-Buckling Analysis of Curved Honeycomb Sandwich Panels Containing Interfacial Disbonds

    NASA Technical Reports Server (NTRS)

    Pineda, Evan J.; Bednarcyk, Brett A.; Krivanek, Thomas K.

    2016-01-01

    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 plan for the next-generation Space Launch System heavy lift launch 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 incorporating geometric nonlinearity. In a predetermined circular region, facesheet and core nodes were detached to simulate a disbond, between the outer mold line facesheet and honeycomb core, induced via low-speed impact. Surface-to-surface contact in the disbonded region was invoked to prevent interpenetration of the facesheet and core elements and obtain realistic stresses in the core. The diameter of this disbonded region was varied and the effect of the size of the disbond on the post-buckling response was observed. Significant changes in the slope of the edge load-deflection response were used to determine the onset of global buckling and corresponding buckling load. Finally, several studies were conducted to determine the sensitivity of the numerical predictions to refinement in the finite element mesh.

  17. Hypervelocity Impact Evaluation of Metal Foam Core Sandwich Structures

    NASA Technical Reports Server (NTRS)

    Yasensky, John; Christiansen, Eric L.

    2007-01-01

    A series of hypervelocity impact (HVI) tests were conducted by the NASA Johnson Space Center (JSC) Hypervelocity Impact Technology Facility (HITF) [1], building 267 (Houston, Texas) between January 2003 and December 2005 to test the HVI performance of metal foams, as compared to the metal honeycomb panels currently in service. The HITF testing was conducted at the NASA JSC White Sands Testing Facility (WSTF) at Las Cruces, New Mexico. Eric L. Christiansen, Ph.D., and NASA Lead for Micro-Meteoroid Orbital Debris (MMOD) Protection requested these hypervelocity impact tests as part of shielding research conducted for the JSC Center Director Discretionary Fund (CDDF) project. The structure tested is a metal foam sandwich structure; a metal foam core between two metal facesheets. Aluminum and Titanium metals were tested for foam sandwich and honeycomb sandwich structures. Aluminum honeycomb core material is currently used in Orbiter Vehicle (OV) radiator panels and in other places in space structures. It has many desirable characteristics and performs well by many measures, especially when normalized by density. Aluminum honeycomb does not perform well in Hypervelocity Impact (HVI) Testing. This is a concern, as honeycomb panels are often exposed to space environments, and take on the role of Micrometeoroid / Orbital Debris (MMOD) shielding. Therefore, information on possible replacement core materials which perform adequately in all necessary functions of the material would be useful. In this report, HVI data is gathered for these two core materials in certain configurations and compared to gain understanding of the metal foam HVI performance.

  18. Advanced radiator concepts utilizing honeycomb panel heat pipes

    NASA Astrophysics Data System (ADS)

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

    1987-10-01

    The feasibility of fabricating and processing moderate temperature range vapor chamber type heat pipes in a low mass honeycomb panel configuration for highly efficient radiator fins for potential use on the 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 thickness, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. A thin-wall all-welded stainless steel design with methanol as the working fluid was the initial prototype unit. It was found that an aluminum panel could not be fabricated in the same manner as a stainless steel panel due to diffusion bonding and resistance welding considerations. Therefore, a formed and welded design was developed. The prototype consists of ten panels welded together into a large panel 122 by 24 by 0.15 in., with a heat rejection capability of 1000 watts and a fin efficiency of essentially 1.0.

  19. 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.

  20. 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.

  1. 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.

  2. Nde of Bonded Aluminum Components on Aircraft Structures

    NASA Astrophysics Data System (ADS)

    Barnard, Daniel J.; Hsu, David K.; Foreman, Cory; Wendt, Scott; Kreitinger, Nicholas A.; Steffes, Gary J.

    2008-02-01

    Bonded aluminum structures have been commonly used on aircraft for many years, and many of these applications include flight control surfaces. These bonded structures can be made up of aluminum face sheets adhesively bonded to a central honeycomb core, or they could also be composed of machined components that are bonded in a tongue-in-groove type manner called Grid-Lock. Nondestructive Inspection (NDI) methods of bonded aluminum structures usually involve the detection of skin-to-core disbonds, core buckling and damage caused by impacts. In the case of Grid-Lock, NDI techniques are focused on the detection of failures in the tongue-in-groove adhesive joint. Three nondestructive inspection methods were applied to honeycomb sandwich structures and Grid-Lock panels. The three methods were computer aided tap test (CATT), air-coupled ultrasonic testing (ACUT), and mechanical impedance analysis (MIA). The honeycomb structures tested consisted of structural panels and flight control surfaces from various aircraft. The Grid-Lock samples tested are laboratory specimens that simulate various defects. Experimental results and comparisons from each of these methods and samples will be presented.

  3. 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

  4. 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.

  5. 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

    Ceriumore » m (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 pore 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

  6. 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

  7. Characterization of the effects of water and disbond on ultrasonic signals in honeycomb composite structures

    NASA Astrophysics Data System (ADS)

    Edwards, A. K.

    The flight control surfaces of the CF188 Hornet are composed of carbon/epoxy skin and aluminum honeycomb core composite material, which has a known susceptibility to water ingress. The rudder is most commonly affected and it is suspected that past in-flight failures have occurred due to the amount of bond degradation between the skin and core. Current inspection techniques involve the use of through-transmission ultrasonic testing. The presence of water within the core, however, provides coupling for the transmission of sound, which can result in the masking of certain disbonded areas. In this study, neutron radiography was used to detect the precise location of water within a test rudder. Through-transmission C-Scan ultrasonic testing was also carried out. Examination of the individual A-Scans revealed that two time-separated signals occurred where water was present. The signal from the sound that travelled down the aluminum core cell walls occurred earlier in time due to the higher velocity of sound in aluminum. The signal from the sound that travelled through the water occurred later as the velocity in water is approximately one quarter of the velocity in aluminum. Analysis of time-gated aluminum signals in the form of C-Scan amplitude or energy plots strongly suggested that the identification of areas of disbond, when water was present, is possible. This identification was achievable since the ultrasound transmission intensity for aluminum bonded to epoxy is three times that in the case of disbond, when water is present between the epoxy and aluminum.

  8. 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

  9. Bending Response of Sandwiched Double Tube Structures with Aluminum Foam Core

    NASA Astrophysics Data System (ADS)

    Guo, L. W.; Yu, J. L.

    2010-05-01

    Three point bending response of sandwiched double cylindrical tube structures with aluminum foam core was studied numerically using the explicit finite element method. The numerical results are in good agreement with the corresponding experimental results and display the advantage of this new structure in load carrying capacity and energy absorption efficiency over the traditional foam-filled single tube structure. The deformation and failure mechanism is revealed by comparisons of the strain and stress distributions and the history of the maximum strain. The influence of the inner tube diameter for the structure was explored. It is found that increasing the inner tube diameter enhances the maximum deflection at failure of the foam-filled double tube within the diameter range considered. With a proper inner tube diameter, a steady load carrying capacity of the foam-filled double tube structure can be achieved, which shows an excellent crashworthiness with high energy absorption efficiency.

  10. 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.

  11. Honeycombs in honeycombs: complex liquid crystal alumina composite mesostructures.

    PubMed

    Zhang, Ruibin; Zeng, Xianbing; Prehm, Marko; Liu, Feng; Grimm, Silko; Geuss, Markus; Steinhart, Martin; Tschierske, Carsten; Ungar, Goran

    2014-05-27

    Small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM) were used to study orientation patterns of two polyphilic liquid crystals (LC) confined to cylindrical pores of anodic aluminum oxide (AAO). The hierarchical hybrid systems had the LC honeycomb (lattice parameter 3.5-4 nm) inside the pores of the AAO honeycomb (diameters 60 and 400 nm). By conducting complete reciprocal space mapping using SAXS, we conclude that the columns of both compounds align in planes normal to the AAO pore axis, with a specific crystallographic direction of the LC lattice aligning strictly parallel to the pore axis. AFM of LC-containing AAO fracture surfaces further revealed that the columns of the planar anchoring LC (compound 1) formed concentric circles in the plane normal to the pore axis near the AAO wall. Toward the pore center, the circles become anisometric "racetrack" loops consisting of two straight segments and two semicircles. This mode compensates for slight ellipticity of the pore cross section. Indications are, however, that for perfectly circular pores, circular shape is maintained right to the center of the pore, the radius coming down to the size of a molecule. For the homeotropically anchoring compound 2, the columns are to the most part straight and parallel to each other, arranged in layers normal to the AAO pore axis, like logs in an ordered pile. Only near the pore wall the columns splay somewhat. In both cases, columns are confined to layers strictly perpendicular to the AAO pore axis, and there is no sign of escape to the third dimension or of axial orientation, the latter having been reported previously for some discotic LCs. The main cause of the two new LC configurations, the "racetrack" and the "logpile", and of their difference from those of confined nematic LC, is the very high splay energy and low bend energy of columnar phases. PMID:24758721

  12. Extruded ceramic honeycomb and method

    DOEpatents

    Day, J. Paul

    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.

  13. Effects of Processing Parameters on the Fabrication of Copper Cladding Aluminum Rods by Horizontal Core-Filling Continuous Casting

    NASA Astrophysics Data System (ADS)

    Su, Ya-Jun; Liu, Xin-Hua; Huang, Hai-You; Wu, Chun-Jing; Liu, Xue-Feng; Xie, Jian-Xin

    2011-02-01

    Copper cladding aluminum (CCA) rods with a diameter of 30 mm and a sheath thickness of 3 mm were fabricated by horizontal core-filling continuous casting (HCFC) technology. The effects of key processing parameters, such as the length of the mandrel tube of composite mold, aluminum casting temperature, flux of the secondary cooling water, and mean withdrawing speed were optimized based on some quality criteria, including the uniformity of the sheath thickness, integrality of the rods, and thickness of the interface. The causes of internal flaws formation of CCA rods were also discussed. The results showed that the continuity of the liquid aluminum core-filling process and the interface reaction control between solid copper and liquid aluminum were two key problems that strongly affected the stability of the casting process and the product quality. Our research indicated that for the CCA rod with the previously mentioned size, the optimal length of mandrel tube was 210 mm. A shorter mandrel tube allowed of easier erosion at the interface, which led to a nonuniform sheath thickness. Conversely, it tended to result in a discontinuous filling process of liquid aluminum, which causes shrinkage or cold shuts. The optimal casting temperatures of copper and aluminum were 1503 K (1230 °C) and 1043 K to 1123 K (770 °C to 850 °C), respectively. When the casting temperature of aluminum was below 1043 K (770 °C), the casting process would be discontinuous, resulting in shrinkages or cold shuts. Nevertheless, when the casting temperature of aluminum was higher than 1123 K (850 °C), a severe interface reaction between solid copper and liquid aluminum would occur. The proper flux of the secondary cooling water and the mean withdrawing speed were determined as 600 to 800 L/h and 60 to 87 mm/min, respectively. In the previously mentioned proper ranges of processing parameters, the interfacial shear strengths of CCA rods were 40.5 to 67.9 MPa.

  14. 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.

  15. Thermal inspection of composite honeycomb structures

    NASA Astrophysics Data System (ADS)

    Zalameda, Joseph N.; Parker, F. Raymond

    2014-05-01

    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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Design Optimization and Analysis of a Composite Honeycomb Intertank

    NASA Technical Reports Server (NTRS)

    Finckenor, Jeff; Spurrier, Mile

    1999-01-01

    Intertanks, the structure between tanks of launch vehicles, are prime candidates for weight reduction of rockets. This paper discusses the optimization and detailed follow up analysis and testing of a 96 in. diameter, 77 in. tall intertank. The structure has composite face sheets with an aluminum honeycomb core. The ends taper to a thick built up laminate for a double lap bolted splice joint interface. It is made in 8 full length panels joined with bonded double lap joints. The nominal load is 4000 lb/in. Optimization is by Genetic Algorithm and minimizes weight by varying core thickness, number and orientation of acreage and buildup plies, and the size, number and spacing of bolts. A variety of design 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 elasticity 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. This analysis and testing resulted in several small changes to the optimized design. The equation used for hole bearing strength was found to be inadequate, resulting in thicker ends. The core thickness increased 0.05", and potting compound was added in the taper to strengthen the facesheet bond. The intertank has undergone a 250,000 lb 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.

  1. 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.

  2. 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.

  3. The dynamic mechanical properties study on the sandwich panel of different thickness steel plate-foam aluminum core

    NASA Astrophysics Data System (ADS)

    Chang, Zhongliang; Zou, Guangping; Zhao, Weiling; Xia, Peixiu

    2009-12-01

    The foam aluminum belongs to multi-cell materials, and it has good mechanical performance, such as large deformation capacity and good energy absorption, and usually used as core material of sandwich panel, now it is widely used in automotive, aviation, aerospace and other fields, particularly suitable for various anti-collision structure and buffer structure. In this article, based on an engineering background, the INSTRON4505 electronic universal testing machine and split Hopkinson pressure bar (SHPB) were used for testing the static and dynamic mechanical properties of sandwich panel with different thickness steel plate- foam aluminum core, from the results we can see that the steel plate thickness has big influence on the stress-strain curve of the sandwich panel, and also takes the sandwich panel with 1mm steel panel to study the material strain rate dependence which under different high shock wave stress loaded, the results show that the sandwich panel is strain rate dependence material. And also, in order to get good waveforms in the SHPB experiment, the waveform shaped technique is used in the dynamic experiments, and the study of this paper will good to sandwich panel used in the engineering.

  4. The dynamic mechanical properties study on the sandwich panel of different thickness steel plate-foam aluminum core

    NASA Astrophysics Data System (ADS)

    Chang, Zhongliang; Zou, Guangping; Zhao, Weiling; Xia, Peixiu

    2010-03-01

    The foam aluminum belongs to multi-cell materials, and it has good mechanical performance, such as large deformation capacity and good energy absorption, and usually used as core material of sandwich panel, now it is widely used in automotive, aviation, aerospace and other fields, particularly suitable for various anti-collision structure and buffer structure. In this article, based on an engineering background, the INSTRON4505 electronic universal testing machine and split Hopkinson pressure bar (SHPB) were used for testing the static and dynamic mechanical properties of sandwich panel with different thickness steel plate- foam aluminum core, from the results we can see that the steel plate thickness has big influence on the stress-strain curve of the sandwich panel, and also takes the sandwich panel with 1mm steel panel to study the material strain rate dependence which under different high shock wave stress loaded, the results show that the sandwich panel is strain rate dependence material. And also, in order to get good waveforms in the SHPB experiment, the waveform shaped technique is used in the dynamic experiments, and the study of this paper will good to sandwich panel used in the engineering.

  5. 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.

  6. Honeycomb lattices with defects

    NASA Astrophysics Data System (ADS)

    Spencer, Meryl A.; Ziff, Robert M.

    2016-04-01

    In this paper, we introduce a variant of the honeycomb lattice in which we create defects by randomly exchanging adjacent bonds, producing a random tiling with a distribution of polygon edges. We study the percolation properties on these lattices as a function of the number of exchanged bonds using an alternative computational method. We find the site and bond percolation thresholds are consistent with other three-coordinated lattices with the same standard deviation in the degree distribution of the dual; here we can produce a continuum of lattices with a range of standard deviations in the distribution. These lattices should be useful for modeling other properties of random systems as well as percolation.

  7. 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.

  8. 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.

  9. 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.

  10. Fastening hardware to honeycomb panels

    NASA Technical Reports Server (NTRS)

    Kenger, A.

    1979-01-01

    Adhesive bonding reduces likelihood of skin failure due to excessive forces or torques by utilizing an adhesive to honeycomb skin. Concept is useful in other applications of composites such as aircraft, automobiles, and home appliances.

  11. Versatile honeycomb matrix heat shield

    NASA Technical Reports Server (NTRS)

    Zell, Peter T. (Inventor)

    2010-01-01

    A thermal protection system for atmospheric entry of a vehicle, the system including a honeycomb structure with selected cross sectional shapes that receives and holds thermally cured thermal protection (TP) blocks that have corresponding cross sectional shapes. Material composition for TP blocks in different locations can be varied to account for different atmospheric heating characteristics at the different locations. TP block side walls may be attached to all, or to less than all, the corresponding honeycomb structure side walls.

  12. Internal stresses in pre-stressed micron-scale aluminum core-shell particles and their improved reactivity

    SciTech Connect

    Levitas, Valery I.; McCollum, Jena; Pantoya, Michelle L.; Tamura, Nobumichi

    2015-09-07

    Dilatation of aluminum (Al) core for micron-scale particles covered by alumina (Al{sub 2}O{sub 3}) shell was measured utilizing x-ray diffraction with synchrotron radiation for untreated particles and particles after annealing at 573 K and fast quenching at 0.46 K/s. Such a treatment led to the increase in flame rate for Al + CuO composite by 32% and is consistent with theoretical predictions based on the melt-dispersion mechanism of reaction for Al particles. Experimental results confirmed theoretical estimates and proved that the improvement of Al reactivity is due to internal stresses. This opens new ways of controlling particle reactivity through creating and monitoring internal stresses.

  13. Surface plasmon interference on the surface of an aluminum-covered fiber core array for solgel fabrication of submicrometer gratings.

    PubMed

    Wang, Wenjie; He, Miao; Zhang, Yong; Li, Shuti; He, Anhe; Wang, Xin; Hu, Candong; Zhu, Qiuxiang; Zhou, Jun; Ning, Guoxiang

    2010-11-15

    An interesting method to fabricate submicrometer gratings (SMGs) utilizing the interference of surface plasmon waves (SPWs) is presented. The stationary wave field off the aluminum (Al) layer surface of an Al-covered UV fiber core, formed by the interference of the induced SPWs, has been employed as a submicrometer photolithography tool to inscribe SMGs on the surface of a self-processing hybrid HfO(2)/SiO(2) solgel film. Using atomic force microscopy, the period of the fabricated SMGs was measured as 105 nm. The intensity distribution of the stationary wave field was measured by a near-field scanning optical microscope and anastomosed with theoretical values calculated by using FDTD simulations. PMID:21082009

  14. High capacity demonstration of honeycomb panel heat pipes

    NASA Technical Reports Server (NTRS)

    Tanzer, H. J.; Cerza, M. R., Jr.; Hall, J. B.

    1986-01-01

    High capacity honeycomb panel heat pipes were investigated as heat rejection radiators on future space platforms. Starting with a remnant section of honeycomb panel measuring 3.05-m long by 0.127-m wide that was originally designed and built for high-efficiency radiator fins, features were added to increase thermal transport capacity and thus permit test evaluation as an integral heat transport and rejection radiator. A series of subscale panels were fabricated and reworked to isolate individual enhancement features. Key to the enhancement was the addition of a liquid sideflow that utilizes pressure priming. A prediction model was developed and correlated with measured data, and then used to project performance to large, space-station size radiators. Results show that a honeycomb panel with 5.08-cm sideflow spacing and core modification will meet the design load of a 50 kW space heat rejection system.

  15. Investigation of honeycomb structure using pulse infrared thermography method

    NASA Astrophysics Data System (ADS)

    Li, Huijuan

    2010-11-01

    To reduce weight and improve strength in the aerospace industry, composite structure has gained popularity as a replacement for conventional materials and structures, such as adhesive bonding and honeycomb structure. Honeycomb structures composed by a honeycomb core between two facesheets are very common on aerospace parts. However, the adhesive bonding process is more susceptible to quality variations during manufacturing than traditional joining methods. With the large increase in the use of composite materials and honeycomb structures, the need for high speed, large area inspection for fracture critical, sub-surface defects in aircraft, missiles and marine composites led to broad acceptance of infrared based NDT methods. Infrared thermography is one of several non-destructive testing techniques which can be used for defect detection in aircraft materials. Infrared thermography can be potentially useful, as it is quick, real time, non-contact and can examine over a relatively large area in one inspection procedure. In this paper, two kinds of defects which are of various size, shape and location below the test surface are planted in the honeycomb structure, they are all tested by pulsed thermography, analyze the thermal sequence and intensity graph got by this methods, it shows that pulsed thermography is an effective nondestructive technique for inspecting disbonding defect, can distinguish the location and the dimension of the defect exactly.

  16. Pulsed phase thermography for defect detection of honeycomb structure

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Feng, Lichun; Li, Yanhong; Zhang, Cunlin

    2009-07-01

    Pulse Phase Thermography (PPT) has been reported as a powerful technique of the thermal NDE. In this paper, the authors show that the original phase-images of two kinds of honeycomb structure defects by PPT based on Fast Fourier Transform (FFT) for the signal of temperature-time of each pixel. One is the artificial defects in honeycomb structure core under surface skin, and the defects can be identified easily. The other is disbonding defect between surface skin and core, and the difference is apparent compared with bonding and no-bonding between surface skin and core. To improve the signal to noise ratio for defect inspection of honeycomb structure, the temperature decay curve of each pixel is smoothed by moving average filter and then fitted by exponential function. After FFT on the fitted data of temperature, the fitted phase-images of two kinds of honeycomb structure defects are given. Compared with the original thermal-images of PT and original phase-images, the calculated phase-images are much more improved. Another advantage is the data could be represented by coefficients of fitting functions, and the storage of data could be greatly reduced. At last, the calculation process of temperature decay curve and analysis of the influence caused by increasing sampling time and frequency are given.

  17. 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.

  18. Method of fabricating a honeycomb structure

    DOEpatents

    Holleran, Louis M.; Lipp, G. Daniel

    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.

  19. Interfacial Microstructure and Bonding Strength of Copper Cladding Aluminum Rods Fabricated by Horizontal Core-Filling Continuous Casting

    NASA Astrophysics Data System (ADS)

    Su, Ya-Jun; Liu, Xin-Hua; Huang, Hai-You; Liu, Xue-Feng; Xie, Jian-Xin

    2011-12-01

    Copper cladding aluminum (CCA) rods with a diameter of 30 mm and a sheath thickness of 3 mm were fabricated by horizontal core-filling continuous casting (HCFC) technology. The microstructure and morphology, distribution of chemical components, and phase composition of the interface between Cu and Al were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), and energy dispersive spectrometer (EDS). The formation mechanism of the interface and the effects of key processing parameters, e.g., aluminum casting temperature, secondary cooling intensity, and mean withdrawing speed on the interfacial microstructure and bonding strength were investigated. The results show that the CCA rod has a multilayered interface, which is composed of three sublayers—sublayer I is Cu9Al4 layer, sublayer II is CuAl2 layer, and sublayer III is composed of α-Al/CuAl2 pseudo eutectic. The thickness of sublayer III, which occupies 92 to 99 pct of the total thickness of the interface, is much larger than the thicknesses of sublayers I and II. However, the interfacial bonding strength is dominated by the thicknesses of sublayers I and II; i.e., the bonding strength decreases with the rise of the thicknesses of sublayers I and II. When raising the aluminum casting temperature, the total thickness of the interface increases while the thicknesses of sublayers I and II decrease and the bonding strength increases. Either augmenting the secondary cooling intensity or increasing the mean withdrawing speed results in the decrease in both total thickness of the interface and the thicknesses of sublayers I and II, and an increase in the interfacial bonding strength. The CCA rod with the largest interfacial bonding strength of 67.9 ± 0.5 MPa was fabricated under such processing parameters as copper casting temperature 1503 K (1230 °C), aluminum casting temperature 1063 K (790 °C), primary cooling water flux 600 L/h, secondary cooling water flux 700 L/h, and

  20. New Double-Infiltration Methodology to Prepare PCL-PS Core-Shell Nanocylinders Inside Anodic Aluminum Oxide Templates.

    PubMed

    Sanz, Belén; Blaszczyk-Lezak, Iwona; Mijangos, Carmen; Palacios, Jordana K; Müller, Alejandro J

    2016-08-01

    Melt nanomolding of core-shell nanocylinders of different sizes, employing anodic aluminum oxide (AAO) templates, is reported here for the first time. The core-shell nanostructures are achieved by a new melt double-infiltration technique. During the first infiltration step, polystyrene (PS) nanotubes are produced by an adequate choice of AAO nanopore diameter size. In the second step, PCL is infiltrated inside the PS nanotubes, as its melting point (and infiltration temperature) is lower than the glass transition temperature of PS. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) measurements verified the complete double-infiltration of the polymers. Differential scanning calorimetry (DSC) experiments show that the infiltrated PCL undergoes a confined fractionated crystallization with two crystallization steps located at temperatures that depend on which surface is in contact with the PCL nanocylinders (i.e., alumina or PS). The melt double-infiltration methodology represents a novel approach to study the effect of the surrounding surface on polymer crystallization under confinement. PMID:27420298

  1. 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.

  2. 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.

  3. Detecting moisture in composite honeycomb panels

    NASA Technical Reports Server (NTRS)

    Culp, J. D.; Sapp, J. W., Jr.

    1979-01-01

    Radiographic inspection technique detects liquids trapped in cells of honeycomb composite panels constructed with porous fiber-reinforced plastic skins. Procedure is of use in industries such as aerospace or automotive engineering where honeycomb composites are being used or studied.

  4. 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.

  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. 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.

  7. 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.

  8. 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.

  9. Mechanical properties of additively manufactured octagonal honeycombs.

    PubMed

    Hedayati, R; Sadighi, M; Mohammadi-Aghdam, M; Zadpoor, A A

    2016-12-01

    Honeycomb structures have found numerous applications as structural and biomedical materials due to their favourable properties such as low weight, high stiffness, and porosity. Application of additive manufacturing and 3D printing techniques allows for manufacturing of honeycombs with arbitrary shape and wall thickness, opening the way for optimizing the mechanical and physical properties for specific applications. In this study, the mechanical properties of honeycomb structures with a new geometry, called octagonal honeycomb, were investigated using analytical, numerical, and experimental approaches. An additive manufacturing technique, namely fused deposition modelling, was used to fabricate the honeycomb from polylactic acid (PLA). The honeycombs structures were then mechanically tested under compression and the mechanical properties of the structures were determined. In addition, the Euler-Bernoulli and Timoshenko beam theories were used for deriving analytical relationships for elastic modulus, yield stress, Poisson's ratio, and buckling stress of this new design of honeycomb structures. Finite element models were also created to analyse the mechanical behaviour of the honeycombs computationally. The analytical solutions obtained using Timoshenko beam theory were close to computational results in terms of elastic modulus, Poisson's ratio and yield stress, especially for relative densities smaller than 25%. The analytical solutions based on the Timoshenko analytical solution and the computational results were in good agreement with experimental observations. Finally, the elastic properties of the proposed honeycomb structure were compared to those of other honeycomb structures such as square, triangular, hexagonal, mixed, diamond, and Kagome. The octagonal honeycomb showed yield stress and elastic modulus values very close to those of regular hexagonal honeycombs and lower than the other considered honeycombs. PMID:27612831

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

    NASA Astrophysics Data System (ADS)

    Bowles, Susan J.; Scala, Christine M.

    1999-12-01

    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.

  11. 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.

  12. 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.

  13. Bosonic edge states in gapped honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Guo, Huaiming; Niu, Yuekun; Chen, Shu; Feng, Shiping

    2016-03-01

    By quantum Monte Carlo simulations of bosons in gapped honeycomb lattices, we show the existence of bosonic edge states. For a single layer honeycomb lattice, bosonic edge states can be controlled to appear, cross the gap, and merge into bulk states by an on-site potential applied on the outermost sites of the boundary. On a bilayer honeycomb lattice, A bosonic edge state traversing the gap at half filling is demonstrated. The topological origin of the bosonic edge states is discussed with pseudo Berry curvature. The results will simulate experimental studies of these exotic bosonic edge states with ultracold bosons trapped in honeycomb optical lattices.

  14. Nanoscale Superconducting Honeycomb Charge Order in IrTe2.

    PubMed

    Kim, Hyo Sung; Kim, Sooran; Kim, Kyoo; Min, Byung Il; Cho, Yong-Heum; Wang, Lihai; Cheong, Sang-Wook; Yeom, Han Woong

    2016-07-13

    Entanglement of charge orderings and other electronic orders such as superconductivity is in the core of challenging physics issues of complex materials including high temperature superconductivity. Here, we report on the observation of a unique nanometer scale honeycomb charge ordering of the cleaved IrTe2 surface, which hosts a superconducting state. IrTe2 was recently established to exhibit an intriguing cascade of stripe charge orders. The stripe phases coexist with a hexagonal phase, which is formed locally and falls into a superconducting state below 3 K. The atomic and electronic structures of the honeycomb and hexagon pattern of this phase are consistent with the charge order nature, but the superconductivity does not survive on neighboring stripe charge order domains. The present work provides an intriguing physics issue and a new direction of functionalization for two-dimensional materials. PMID:27221583

  15. Nanoscale Superconducting Honeycomb Charge Order in IrTe2

    NASA Astrophysics Data System (ADS)

    Kim, Hyo Sung; Kim, Sooran; Kim, Kyoo; Min, Byung Il; Cho, Yong-Heum; Wang, Lihai; Cheong, Sang-Wook; Yeom, Han Woong

    2016-07-01

    Entanglement of charge orderings and other electronic orders such as superconductivity is in the core of challenging physics issues of complex materials including high temperature superconductivity. Here, we report on the observation of a unique nanometer scale honeycomb charge ordering of the cleaved IrTe2 surface, which hosts a superconducting state. IrTe2 was recently established to exhibit an intriguing cascade of stripe charge orders. The stripe phases coexist with a hexagonal phase, which is formed locally and falls into a superconducting state below 3 K. The atomic and electronic structures of the honeycomb and hexagon pattern of this phase are consistent with the charge order nature but the superconductivity does not survive on neighboring stripe charge order domains. The present work provides an intriguing physics issue and a new direction of functionalization for two dimensional materials.

  16. Development of Pyrrone structural forms for honeycomb filler

    NASA Technical Reports Server (NTRS)

    Kimmel, B. G.

    1973-01-01

    The development of techniques for the preparation of Pyrrone structural foams for use as honeycomb filler is described. The feasibility of preparing foams from polymers formed by the condensation of 3,3'-diaminobenzidine (DAB), or 3,3',4,4'-tetraaminobenzophenone (TABP), with 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) was investigated. Initially, most of the effort was devoted to preparing Pyrrone prepolymers with improved and more reproducible foaming properties for making chemically blown foams. When it became apparent that very high curing shrinkages would not allow the use of unfilled Pyrrone prepolymers in a foam-in-place process, emphasis was shifted from chemically blown foams to syntactic foams. Syntactic foam formulations containing hollow carbon microspheres were developed. Syntactic foams made from selected formulations were found to have very low coefficients of thermal expansion. A technique was developed for the emplacement of Pyrrone syntactic foam formulations in honeycomb core structures.

  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

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

    NASA Technical Reports Server (NTRS)

    Ryan, Shannon; Christiansen, Eric; Lear, Dana

    2009-01-01

    Metallic foams are a relatively new class of materials with low density and novel physical, mechanical, thermal, electrical and acoustic properties. Although incompletely characterized, they offer comparable mechanical performance to traditional spacecraft structural materials (i.e. honeycomb sandwich panels) without detrimental through-thickness channeling cells. There are two competing types of metallic foams: open cell and closed cell. Open cell foams are considered the more promising technology due to their lower weight and higher degree of homogeneity. Leading micrometeoroid and orbital debris shields (MMOD) incorporate thin plates separated by a void space (i.e. Whipple shield). Inclusion of intermediate fabric layers, or multiple bumper plates have led to significant performance enhancements, yet these shields require additional non-ballistic mass for installation (fasteners, supports, etc.) that can consume up to 35% of the total shield weight [1]. Structural panels, such as open cell foam core sandwich panels, that are also capable of providing sufficient MMOD protection, represent a significant potential for increased efficiency in hypervelocity impact shielding from a systems perspective through a reduction in required non-ballistic mass. In this paper, the results of an extensive impact test program on aluminum foam core sandwich panels are reported. The effect of pore density, and core thickness on shielding performance have been evaluated over impact velocities ranging from 2.2 - 9.3 km/s at various angles. A number of additional tests on alternate sandwich panel configurations of comparable-weight have also been performed, including aluminum honeycomb sandwich panels (see Figure 1), Nomex honeycomb core sandwich panels, and 3D aluminum honeycomb sandwich panels. A total of 70 hypervelocity impact tests are reported, from which an empirical ballistic limit equation (BLE) has been derived. The BLE is in the standard form suitable for implementation in

  19. Increased power to weight ratio of piezoelectric energy harvesters through integration of cellular honeycomb structures

    NASA Astrophysics Data System (ADS)

    Chandrasekharan, N.; Thompson, L. L.

    2016-04-01

    The limitations posed by batteries have compelled the need to investigate energy harvesting methods to power small electronic devices that require very low operational power. Vibration based energy harvesting methods with piezoelectric transduction in particular has been shown to possess potential towards energy harvesters replacing batteries. Current piezoelectric energy harvesters exhibit considerably lower power to weight ratio or specific power when compared to batteries the harvesters seek to replace. To attain the goal of battery-less self-sustainable device operation the power to weight ratio gap between piezoelectric energy harvesters and batteries need to be bridged. In this paper the potential of integrating lightweight honeycomb structures with existing piezoelectric device configurations (bimorph) towards achieving higher specific power is investigated. It is shown in this study that at low excitation frequency ranges, replacing the solid continuous substrate of conventional bimorph with honeycomb structures of the same material results in a significant increase in power to weight ratio of the piezoelectric harvester. At higher driving frequency ranges it is shown that unlike the traditional piezoelectric bimorph with solid continuous substrate, the honeycomb substrate bimorph can preserve optimum global design parameters through manipulation of honeycomb unit cell parameters. Increased operating lifetime and design flexibility of the honeycomb core piezoelectric bimorph is demonstrated as unit cell parameters of the honeycomb structures can be manipulated to alter mass and stiffness properties of the substrate, resulting in unit cell parameter significantly influencing power generation.

  20. 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

  1. Design of composite hollow-core panels

    SciTech Connect

    Philippe, M.H.; Naciri, T.; Ehrlacher, A.

    1996-11-01

    A design method is proposed to describe the static behavior of hollow-core panels under flexure. These panels are made of diagonal stiffeners placed between two faces with a composite material (carbon-epoxy). The hollow-core panels and the design method were both developed by the ENPC for the making of structural components having a high stiffness/weight ratio. An analytical model based on a periodic media homogenization method was developed to obtain the constitutive law of the equivalent homogeneous panel. The accuracy of this model was assessed by comparing the calculated deflections with those of another 3D finite element model. An optimization method, based on the Euler equations, was further developed to provide the minimum weight for a given deflection. The faces and the stiffeners thicknesses were set as variables for the optimization process. With the partnership of the SNCF (the French railroads company), this method was applied to the design of the intermediate floor of the two-levels cabins for the TGV trains (high speed trains). The deflection of the aluminum honeycomb core sandwich floor already used by the SNCF was computed and, afterwards, the optimization method was used to find a hollow-core floor having the same deflection but a minimum weight. The results of the optimization clearly indicate that it is possible to reduce the aluminum TGV floor weight to one third.

  2. Fabrication and development of several heat pipe honeycomb sandwich panel concepts. [airframe integrated scramjet engine

    NASA Technical Reports Server (NTRS)

    Tanzer, H. J.

    1982-01-01

    The feasibility of fabricating and processing liquid metal heat pipes in a low mass honeycomb sandwich panel configuration for application on the NASA Langley airframe-integrated Scramjet engine was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts was evaluated within constraints dictated by existing manufacturing technology and equipment. The chosen design consists of an all-stainless steel structure, sintered screen facesheets, and two types of core-ribbon; a diffusion bonded wire mesh and a foil-screen composite. Cleaning, fluid charging, processing, and process port sealing techniques were established. The liquid metals potassium, sodium and cesium were used as working fluids. Eleven honeycomb panels 15.24 cm X 15.24 cm X 2.94 cm were delivered to NASA Langley for extensive performance testing and evaluation; nine panels were processed as heat pipes, and two panels were left unprocessed.

  3. Detection of Skin Disbond in Honeycombs and Coating Detachment by a Laser Acoustic Technique

    NASA Astrophysics Data System (ADS)

    Blouin, A.; Campagne, B.; Néron, C.; Monchalin, J.-P.

    2007-03-01

    Many engineering structures are composite and include for example a protective coating or a bonded layer. A novel technique, close to laser-ultrasonics but significantly different, has been developed for the detection of disbonds between the coating or the bonded layer and the substrate. It is also applicable to the detection of core unbonds in honeycomb structures. The technique is based on the thermoelastic excitation by a pulsed laser of the top layer or top skin which is driven into vibration if it is detached from the substrate underneath. This vibration is then detected by a second laser coupled to a photorefractive interferometer. The technique can be made very flexible by using optical fiber coupling. One foresees its application to the in-service inspection of aerospace structures for the detection of core unbonds in honeycombs or near surface delaminations. Examples of application to honeycombs and to various coatings are presented.

  4. Fabrication and development of several heat pipe honeycomb sandwich panel concepts. Final report

    SciTech Connect

    Tanzer, H.J.

    1982-06-01

    The feasibility of fabricating and processing liquid metal heat pipes in a low mass honeycomb sandwich panel configuration for application on the NASA Langley airframe-integrated Scramjet engine was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts was evaluated within constraints dictated by existing manufacturing technology and equipment. The chosen design consists of an all-stainless steel structure, sintered screen facesheets, and two types of core-ribbon, a diffusion bonded wire mesh and a foil-screen composite. Cleaning, fluid charging, processing, and process port sealing techniques were established. The liquid metals, potassium, sodium and cesium were used as working fluids. Eleven honeycomb panels 15.24 cm X 15.24 cm X 2.94 cm were delivered to NASA Langley for extensive performance testing and evaluation, nine panels were processed as heat pipes, and two panels were left unprocessed.

  5. Double core-hole emissivity of transient aluminum plasmas produced in the interaction with ultra-intense x-ray laser pulse

    NASA Astrophysics Data System (ADS)

    Gao, Cheng; Zeng, Jiaolong; Yuan, Jianmin

    2015-11-01

    Emissivity of single core-hole (SCH) and double core-hole (DCH) states of aluminum plasmas produced in the interaction with ultra-intense x-ray laser pulse interaction are investigated systematically by solving the time-dependent rate equation implemented in the detailed level accounting approximation. We first demonstrated the plasma density effects on level populations and charge state distribution. Compared with recent experiments, it is shown that the plasma density effects play important roles in the evolution dynamics. Then we systematically investigated the emissivity of the transient aluminum plasmas produced by the x-ray laser pulses with a few photon energies above the threshold photon energy to create DCH states. For the laser photon energy where there are resonant absorptions (RA), 1s-np transitions with both full 1s and SCH 1s states play important roles in time evolution of the population and DCH emission spectroscopy. The significant RA effects are illustrated in detail for x-ray pulses, which creates the 1s-2p resonant absorption from the SCH states of Al VII. With the increase of the photon energy, the emissions from lower charge states become larger.

  6. Crashworthiness analysis on alternative square honeycomb structure under axial loading

    NASA Astrophysics Data System (ADS)

    Li, Meng; Deng, Zongquan; Guo, Hongwei; Liu, Rongqiang; Ding, Beichen

    2013-07-01

    Hexagonal metal honeycomb is widely used in energy absorption field for its special construction. However, many other metal honeycomb structures also show good energy absorption characteristics. Currently, most of the researches focus on hexagonal honeycomb, while few are performed into different honeycomb structures. Therefore, a new alternative square honeycomb is developed to expand the non-hexagonal metal honeycomb applications in the energy absorption fields with the aim of designing low mass and low volume energy absorbers. The finite element model of alternative square honeycomb is built to analyze its specific energy absorption property. As the diversity of honeycomb structure, the parameterized metal honeycomb finite element analysis program is conducted based on PCL language. That program can automatically create finite element model. Numerical results show that with the same foil thickness and cell length of metal honeycomb, the alternative square has better specific energy absorption than hexagonal honeycomb. Using response surface method, the mathematical formulas of honeycomb crashworthiness properties are obtained and optimization is done to get the maximum specific energy absorption property honeycomb. Optimal results demonstrate that to absorb same energy, alternative square honeycomb can save 10% volume of buffer structure than hexagonal honeycomb can do. This research is significant in providing technical support in the extended application of different honeycomb used as crashworthiness structures, and is absolutely essential in low volume and low mass energy absorber design.

  7. Square lattice honeycomb reactor for space power and propulsion

    NASA Astrophysics Data System (ADS)

    Gouw, Reza; Anghaie, Samim

    2000-01-01

    The most recent nuclear design study at the Innovative Nuclear Space Power and Propulsion Institute (INSPI) is the Moderated Square-Lattice Honeycomb (M-SLHC) reactor design utilizing the solid solution of ternary carbide fuels. The reactor is fueled with solid solution of 93% enriched (U,Zr,Nb)C. The square-lattice honeycomb design provides high strength and is amenable to the processing complexities of these ultrahigh temperature fuels. 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. The M-SLHC design is based on a cylindrical core that has critical radius and length of 37 cm and 50 cm, respectively. This design utilized zirconium hydrate to act as moderator. The fuel sub-assemblies are designed as cylindrical tubes with 12 cm in diameter and 10 cm in length. Five fuel subassemblies are stacked up axially to form one complete fuel assembly. These fuel assemblies are then arranged in the circular arrangement to form two fuel regions. The first fuel region consists of six fuel assemblies, and 18 fuel assemblies for the second fuel region. A 10-cm radial beryllium reflector in addition to 10-cm top axial beryllium reflector is used to reduce neutron leakage from the system. To perform nuclear design analysis of the M-SLHC design, a series of neutron transport and diffusion codes are used. To optimize the system design, five axial regions are specified. In each axial region, temperature and fuel density are varied. The axial and radial power distributions for the system are calculated, as well as the axial and radial flux distributions. Temperature coefficients of the system are also calculated. A water submersion accident scenario is also analyzed for these systems. Results of the nuclear design analysis indicate that a compact core can be designed based on ternary uranium carbide square-lattice honeycomb fuel, which provides a relatively

  8. Ceramic Honeycomb Structures and Method Thereof

    NASA Technical Reports Server (NTRS)

    Cagliostro, Domenick E.; Riccitiello, Salvatore R.

    1989-01-01

    The present invention relates to a method for producing ceramic articles and the articles, the process comprising the chemical vapor deposition (CVD) and/or chemical vapor infiltration (CVI) of a honeycomb structure. Specifically the present invention relates to a method for the production of a ceramic honeycomb structure, including: (a) obtaining a loosely woven fabric/binder wherein the fabric consists essentially of metallic, ceramic or organic fiber and the binder consists essentially of an organic or inorganic material wherein the fabric/binder has and retains a honeycomb shape, with the proviso that when the fabric is metallic or ceramic the binder is organic only; (b) substantially evenly depositing at least one layer of a ceramic on the fabric/binder of step (a); and (c) recovering the ceramic coated fiber honeycomb structure. In another aspect, the present invention relates to a method for the manufacture of a lightweight ceramic-ceramic composite honeycomb structure, which process comprises: (d) pyrolyzing a loosely woven fabric a honeycomb shaped and having a high char yield and geometric integrity after pyrolysis at between about 700 degrees and 1,100 degrees Centigrade; (e) substantially evenly depositing at least one layer of ceramic material on the pyrolyzed fabric of step (a); and (f) recovering the coated ceramic honeycomb structure. The ceramic articles produced have enhanced physical properties and are useful in aircraft and aerospace uses.

  9. Study of the core-corona structure formed during the explosion of an aluminum wire in vacuum

    SciTech Connect

    Tkachenko, S. I.; Mingaleev, A. R.; Pikuz, S. A.; Romanova, V. M.; Khattatov, T. A.; Shelkovenko, T. A.; Ol'khovskaya, O. G.; Gasilov, V. A.; Kalinin, Yu. G.

    2012-01-15

    The time evolution of the matter parameters and current distribution in the discharge channel formed during a nanosecond explosion of a 25-{mu}m-diameter 12-mm-long aluminum wire was studied in a series of experiments with the following parameters: the discharge voltage was U{sub 0} = 20 kV, the current amplitude was I{sub max} {approx} 8 kA, and the current rise rate was dI/dt {approx} 40 A/ns. Optical shadow and schlieren images of the discharge channel were obtained using the second harmonic of a YAG: Nd{sup +3} laser, and UV images of the discharge channel self-radiation were recorded using a four-frame camera with a microchannel plate. The process of aluminum wire explosion was simulated numerically (including simulations performed from the 'cold start'). The numerical results were compared with the experimental data.

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

    NASA Astrophysics Data System (ADS)

    Yan, Jiaxue

    Honeycomb structures are widely used in many areas for their material characteristics such as high strength-to-weight ratio, stiffness-to-weight, sound transmission, and other properties. Honeycomb structures are generally constructed from periodically spaced tessellations of unit cells. It can be shown that the effective stiffness and mass properties of honeycomb are controlled by the local geometry and wall thickness of the particular unit cells used. Of particular interest are regular hexagonal (6-sided) honeycomb unit cell geometries which exhibit positive effective Poisson's ratio, and modified 6-sided auxetic honeycomb unit cells with Poisson's ratio which is effectively negative; a property not found in natural materials. One important honeycomb meta-structure is sandwich composites designed with a honeycomb core bonded between two panel layers. By changing the geometry of the repetitive unit cell, and overall depth and material properties of the honeycomb core, sandwich panels with different vibration and acoustic properties can be designed to shift resonant frequencies and improve intensity and Sound Transmission Loss (STL). In the present work, a honeycomb finite element model based on beam elements is programmed in MATLAB and verified with the commercial finite element software ABAQUS for frequency extraction and direct frequency response analysis. The MATLAB program was used to study the vibration and acoustic properties of different kinds of honeycomb sandwich panels undergoing in-plane loading with different incident pressure wave angles and frequency. Results for the root mean square intensity IRMS based on normal velocity on the transmitted side of the panel measure vibration magnitude are reported for frequencies between 0 and 1000 Hz. The relationship between the sound transmission loss computed with ABAQUS and the inverse of the intensity of surface velocity is established. In the present work it is demonstrated that the general trend between the

  11. 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.

  12. Properties of honeycomb polyester knitted fabrics

    NASA Astrophysics Data System (ADS)

    Feng, A. F.

    2016-07-01

    The properties of honeycomb polyester weft-knitted fabrics were studied to understand their advantages. Seven honeycomb polyester weft-knitted fabrics and one common polyester weft-knitted fabric were selected for testing. Their bursting strengths, fuzzing and pilling, air permeability, abrasion resistance and moisture absorption and perspiration were studied. The results show that the honeycomb polyester weft-knitted fabrics have excellent moisture absorption and liberation. The smaller their thicknesses and area densities are, the better their moisture absorption and liberation will be. Their anti-fuzzing and anti-pilling is good, whereas their bursting strengths and abrasion resistance are poorer compared with common polyester fabric's. In order to improve the hygroscopic properties of the fabrics, the proportion of the honeycomb microporous structure modified polyester in the fabrics should not be less than 40%.

  13. 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.

  14. An elastic analysis of a honeycomb structure with negative Poisson’s ratio

    NASA Astrophysics Data System (ADS)

    Zhang, Z. K.; Hu, H.; Xu, B. G.

    2013-08-01

    This paper presents a novel honeycomb structure that exhibits a negative Poisson’s ratio (NPR). In contrast to other NPR honeycomb structures studied in the past, the new structure can be easily fabricated using conventional technology and materials on a large scale of production with a low cost. The geometry of the structure is first described, and then an elastic analysis based on standard beam theory is carried out to establish the relation of its Young’s modulus with relevant geometrical parameters and material properties. The effects of the geometrical parameters in non-dimensional forms on the Young’s modulus of the structure are discussed. The compressive tests were performed on samples of the structure made with the same aluminum alloy but with different geometrical parameters to verify the theoretical analysis. The results obtained from both the theoretical calculations and experiments show that the proposed NPR honeycomb structure has a very obvious NPR behavior. Moreover, its elastic modulus is significantly affected by its geometrical parameters, and can be optimized for specific applications through the design and control of honeycomb geometry parameters.

  15. 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).

  16. Compressive failure modes and parameter optimization of the trabecular structure of biomimetic fully integrated honeycomb plates.

    PubMed

    Chen, Jinxiang; Tuo, Wanyong; Zhang, Xiaoming; He, Chenglin; Xie, Juan; Liu, Chang

    2016-12-01

    To develop lightweight biomimetic composite structures, the compressive failure and mechanical properties of fully integrated honeycomb plates were investigated experimentally and through the finite element method. The results indicated that: fracturing of the fully integrated honeycomb plates primarily occurred in the core layer, including the sealing edge structure. The morphological failures can be classified into two types, namely dislocations and compactions, and were caused primarily by the stress concentrations at the interfaces between the core layer and the upper and lower laminations and secondarily by the disordered short-fiber distribution in the material; although the fully integrated honeycomb plates manufactured in this experiment were imperfect, their mass-specific compressive strength was superior to that of similar biomimetic samples. Therefore, the proposed bio-inspired structure possesses good overall mechanical properties, and a range of parameters, such as the diameter of the transition arc, was defined for enhancing the design of fully integrated honeycomb plates and improving their compressive mechanical properties. PMID:27612711

  17. Thermographic nondestructive testing (TNDT) of honeycomb composite structural parts of Atlas space launch vehicles

    SciTech Connect

    Burleigh, D.D.; Kuhns, D.R.; Cowell, S.D.; Engel, J.E.

    1994-12-31

    Thermography is a means of recording the patterns of heat emission from a surface. Thermographic nondestructive testing (TNDT) uses this technology to detect sub-surface defects. Generally, a heat pulse is applied to a surface that is thermographically monitored. If a sub-surface defect exists that locally reduces or improves the thermal properties of the material, the surface thermal pattern will be perturbed over the defect. TNDT has been used successfully on a wide variety of composite laminates, filament-wound structures, sandwich structures, and foam-insulated cryogenic tanks. Both real structures with real delamination and impact damage, as well as test panels with simulated delaminations, face sheet disbonds, and interply implants have been tested. For some of these applications, TNDT is the best technique. The thrust structure at the aft end of the Atlas space launch vehicle is a composite sandwich comprised of aluminum honeycomb core with fiberglass/phenolic face sheets. The surface area of this structure is approximately 600 ft{sup 2}. In 1992, General Dynamics Space Systems Division (GDSS) began using TNDT for quality verification of these complex composite parts. TNDT has been used on these parts during manufacture and assembly, and on the launch pad at Cape Canaveral. The NDT technique previously used on these parts, since their design in 1957, was ``coin tap.`` Compared to this method, TNDT provides a greatly improved inspection in less time and at a lower cost. A heat gun with a diffuser attachment is used to heat the inspection area while the area is monitored thermographically. TNDT is a rapid, remote, non-contact, highly portable, real-time scanning technique that can provide a well-documented video record of subsurface structural details including facesheet disbonds and skin delaminations. A specification and test procedure has been written, equipment has been procured, and personnel have been trained and certified.

  18. 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

  19. The dynamic shear properties of structural honeycomb materials

    NASA Astrophysics Data System (ADS)

    Adams, R. D.; Maheri, M. R.

    A technique is described for measuring the dynamic modulus and damping of honeycomb materials. Results of tests on both aluminium and Nomex honeycombs are presented and compared with those reported in the literature.

  20. Detecting water in aviation honeycomb structures by using transient infrared thermographic NDT

    NASA Astrophysics Data System (ADS)

    Vavilov, Vladimir P.; Klimov, Alexey G.; Nesteruk, Dmitry; Shiryaev, Vladimir V.

    2003-04-01

    A lot of structural key elements of many modern civilian and military airplanes, such as flaps, keel, etc., are made of honeycomb structures. Honeycombs involve a combination of some materials including aluminum, Nomex, glass and graphite epoxy composites. During exploitation, atmosphere water could penetrate these structures due to possible imperfections in various junctions, and, thus, deteriorate airplane durability. In Russia, water in honeycombs is typically detected by using the X ray and ultrasonic technique. However, the X ray equipment is hardly accepted by commercial airlines because of the safety reason, and the point-by-point ultrasonic inspection is low-productive. Since 2002, we develop the IR thermographic method of detecting water by thermally stimulating aviation panels under test. Unlike the technique accepted by Airbus Industry, Inc., that uses 'a warm blanket', we use a powerful optical heater assembled with an IR camera into a single set. The first stage of research included modeling the detection process and optimizing the experimental procedure. As a result, we have demonstrated that, due to the high heat capacity of water, a temperature signal over moist areas evolves in time during a relatively long period that relaxes the requirements to the test protocol. Thus, even aluminum panels can be thermally stimulated during few seconds with a delay time being also in a few second range. A similar protocol can be applied to the inspection of composite honeycombs where the image quality resembles that obtained by X rays. The paper will describe all stages of the research starting from modeling and finishing with the preliminary experimental results obtained in situ on civilian airplanes.

  1. 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.

  2. Sensing and actuation of smart chiral honeycombs

    NASA Astrophysics Data System (ADS)

    Abramovitch, H.; Burgard, M.; Edery-Azulay, Lucy; Evans, K. E.; Hoffmeister, M.; Miller, W.; Scarpa, F.; Smith, C. W.; Tee, K. F.; Schönecker, A.; Seffner, L.

    2008-03-01

    A chiral honeycomb configuration is developed with embedded piezosensors and actuators for smart sandwich panel applications. The chiral honeycomb concept is made of repeating units of cylinders and plates (ligaments), featuring an in-plane negative Poisson's ratio. Rapid Prototyping vacuum-cast and FDM (Fusion Deposition Moulding) techniques are developed to embed micro fibres composites to be used for potential structural health monitoring (SHM) applications, and microwave absorption screens for electromagnetic compatibility. Finite Element models are also developed to prototype and simulate the response, sensing and actuation capability of the honeycombs for design purposes. Dynamic tests using scanning laser vibrometers and acoustic wave propagation are carried out to assess the feasibility of the concept.

  3. 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.

  4. 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.

  5. Reduced fidelity in the Kitaev honeycomb model

    SciTech Connect

    Wang, Zhi; Ma, Tianxing; Gu, Shi-Jian; Lin, Hai-Qing

    2010-06-15

    We study reduced fidelity and reduced fidelity susceptibility in the Kitaev honeycomb model. It is shown that the nearest-two-site reduced fidelity susceptibility manifests itself as a peak at the quantum phase transition point, although the one-site reduced fidelity susceptibility vanishes. Our results directly reveal that the reduced fidelity susceptibility can be used to characterize the quantum phase transition in the Kitaev honeycomb model, which suggests that, despite its local nature, the reduced fidelity susceptibility is an accurate marker of the topological phase transition when it is properly chosen.

  6. Method and apparatus for extruding large honeycombs

    SciTech Connect

    Kragle, Harry A.; Lambert, David W.; Lipp, G. Daniel

    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.

  7. 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

  8. 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.

  9. 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.

  10. 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)

  11. [Removal and Recycle of Phosphor from Water Using Magnetic Core/Shell Structured Fe₃O₄ @ SiO₂Nanoparticles Functionalized with Hydrous Aluminum Oxide].

    PubMed

    Lai, Li; Xie, Qiang; Fang, Wen-kan; Xing, Ming-chao; Wu, De-yi

    2016-04-15

    A novel magnetic core/shell structured nano-particle Fe₃O₄@ SiO₂phosphor-removal ahsorbent functionalized with hydrous aluminum oxides (Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O) was synthesized. Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O was characterized by XRD, TEM, VSM and BET nitrogen adsorption experiment. The XRD and TEM results demonstrated the presence of the core/shell structure, with saturated magnetization and specific surface area of 56.00 emu · g⁻¹ and 47.27 m² · g⁻¹, respectively. In batch phosphor adsorption experiment, the Langmuir adsorption maximum capacity was 12.90 mg · g⁻¹ and nearly 96% phosphor could be rapidly removed within a contact time of 40 mm. Adsorption of phosphor on Fe₃O₄@ SiO₂@ Al₂O₃ · nH₂O was highly dependent on pH condition, and the favored pH range was 5-9 in which the phosphor removal rate was above 90%. In the treatment of sewage water, the recommended dosage was 1.25 kg · t⁻¹. In 5 cycles of adsorption-regeneration-desorption experiment, over 90% of the adsorbed phosphor could be desorbed with 1 mol · L⁻¹ NaOH, and Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O could be reused after regeneration by pH adjustment with slightly decreased phosphor removal rate with increasing recycling number, which proved the recyclability of Fe₃O₄@ SiO₂@ Al₂O₃· nH₂O and thereby its potential in recycling of phosphor resources. PMID:27548967

  12. Light weight aluminum optics

    NASA Astrophysics Data System (ADS)

    Catura, R. C.; Vieira, J. R.

    1985-09-01

    Light weight mirror blanks were fabricated by dip-brazing a core of low mass aluminum foam material to thin face sheets of solid aluminum. The blanks weigh 40% of an equivalent size solid mirror and were diamond turned to provide reflective surfaces. Optical interferometry was used to assess their dimensional stability over 7 months. No changes in flatness are observed (to the sensitivity of the measurements of a half wavelength of red light).

  13. High heat flux actively cooled honeycomb sandwich structural panel for a hypersonic aircraft

    NASA Technical Reports Server (NTRS)

    Koch, L. C.; Pagel, L. L.

    1978-01-01

    The results of a program to design and fabricate an unshielded actively cooled structural panel for a hypersonic aircraft are presented. The design is an all-aluminum honeycomb sandwich with embedded cooling passages soldered to the inside of the outer moldline skin. The overall finding is that an actively cooled structure appears feasible for application on a hypersonic aircraft, but the fabrication process is complex and some material and manufacturing technology developments are required. Results from the program are summarized and supporting details are presented.

  14. Acoustic scattering response of hierarchic honeycomb structures for cylindrical and spherical structures

    NASA Astrophysics Data System (ADS)

    Mor, Arun

    Sandwich panels with honeycomb core are often employed in structures for improved mechanical properties with lightweight. Honeycombs are defined by non-overlapping and periodic unit cells. Most research conducted on these sandwich panels focuses on stiffness and strength properties. The acoustic aspect of these panels has been focused on sound transmission loss. For acoustics, previous studies used effective honeycomb orthotropic elastic moduli based on Cartesian unit cell geometry to model the core as a homogeneous structure. While efficient, this modeling approach loses accuracy at higher frequencies. Furthermore, when used for curved panels, the effective moduli are only approximate. In this work, mechanical and acoustic characteristics of cylindrical and spherical honeycomb panels are studied using finite element analysis. The unit cell geometry core is oriented both radially and in the transverse direction. The models are analyzed for sound scattering measured by target strength with interactions between structure and the acoustic medium through coupling between the domains. Both air and water are compared for the acoustic region. Different honeycomb core geometries varying in the hexagon arrangement, number of unit cells and level of hierarchy are studied. The structures developed are constrained to have the same total mass allowing for comparisons based on only changes in stiffness properties. The effect of face sheet thickness on the mechanical and acoustic properties of the curved sandwich structures is also studied. The vibration and acoustic scattering behavior of these structures have been investigated for natural frequencies between 1-1000 Hz to predict and understand the different responses near and at resonances. The target strength response of the structures has been studied in the near field at both front and back of the structures. The effect of acoustic coupling is observed clearly on varying the outer domains properties between air and water. It

  15. Finite Element Analysis of Honeycomb Impact Attenuator

    NASA Astrophysics Data System (ADS)

    Yang, Seung-Yong; Choi, Seung-Kyu; Kim, Nohyu

    To participate in Student Formula Society of Automotive Engineers (SAE) competitions, it is necessary to build an impact attenuator that would give an average deceleration not to exceed 20g when it runs into a rigid wall. Students can use numerical simulations or experimental test data to show that their car satisfies this safety requirement. A student group to study formula cars at the Korea University of Technology and Education has designed a vehicle to take part in a SAE competition, and a honeycomb structure was adopted as the impact attenuator. In this paper, finite element calculations were carried out to investigate the dynamic behavior of the honeycomb attenuator. Deceleration and deformation behaviors were studied. Effect of the yield strength was checked by comparing the numerical results. ABAQUS/Explicit finite element code was used.

  16. 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.

  17. Microdischarges in ceramic foams and honeycombs

    NASA Astrophysics Data System (ADS)

    Hensel, K.

    2009-08-01

    Microdischarges in spatially confined geometries, such as microcavities and micropores of various materials, present a promising method for the generation and maintenance of stable discharges at atmospheric pressure. They have been successfully used in many biomedical, environmental and industrial applications. The paper presents two relatively new types of discharges in confined volumes - a capillary microdischarge in ceramic foams and a sliding discharge inside the capillaries of ceramic honeycombs - and describes their basic physical properties and mechanisms. Microdischarges inside the microporous ceramic foams develop from the surface barrier discharge if the amplitude of the applied voltage reaches given threshold, but only for a specific pore size. Sliding discharge inside the honeycomb capillaries is produced by a combination of AC barrier discharge inside catalytic pellet bed coupled in series with DC powered honeycomb monolith. Both discharges produce relatively cold microplasmas with high level of non-equilibrium. The basic characteristics of the microdischarges, addressing the effects of the applied voltage, discharge power, pore size, length and diameter of the capillaries are discussed.

  18. Calculation of the elastic properties of a triangular cell core for lightweight composite mirrors

    NASA Astrophysics Data System (ADS)

    Penado, F. Ernesto; Clark, James H., III; Walton, Joshua P.; Romeo, Robert C.; Martin, Robert N.

    2007-09-01

    The use of composite materials in the fabrication of optical telescope mirrors offers many advantages over conventional methods, including lightweight, portability and the potential for lower manufacturing costs. In the construction of the substrate for these mirrors, sandwich construction offers the advantage of even lower weight and higher stiffness. Generally, an aluminum or Nomex honeycomb core is used in composite applications requiring sandwich construction. However, the use of a composite core offers the potential for increased stiffness and strength, low thermal distortion compatible with that of the facesheets, the absence of galvanic corrosion and the ability to readily modify the core properties. In order to design, analyze and optimize these mirrors, knowledge of the mechanical properties of the core is essential. In this paper, the mechanical properties of a composite triangular cell core (often referred to as isogrid) are determined using finite element analysis of a representative unit cell. The core studied offers many advantages over conventional cores including increased thermal and dimensional stability, as well as low weight. Results are provided for the engineering elastic moduli of cores made of high stiffness composite material as a function of the ply layup and cell size. Finally, in order to illustrate the use of these properties in a typical application, a 1.4-m diameter composite mirror is analyzed using the finite element method, and the resulting stiffness and natural frequencies are presented.

  19. 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

  20. Epitaxial Graphene on SiC(0001): More than Just Honeycombs

    NASA Astrophysics Data System (ADS)

    Qi, Y.; Rhim, S. H.; Sun, G. F.; Weinert, M.; Li, L.

    2010-08-01

    Using scanning tunneling microscopy with Fe-coated W tips and first-principles calculations, we show that the interface of epitaxial graphene/SiC(0001) is a warped graphene layer with hexagon-pentagon-heptagon (H5,6,7) defects that break the honeycomb symmetry, thereby inducing a gap and states below EF near the K point. Although the next graphene layer assumes the perfect honeycomb lattice, its interaction with the warped layer modifies the dispersion about the Dirac point. These results explain recent angle-resolved photoemission and carbon core-level shift data and solve the long-standing problem of the interfacial structure of epitaxial graphene on SiC(0001).

  1. Epitaxial graphene on SiC(0001): More than just honeycombs

    NASA Astrophysics Data System (ADS)

    Li, L.; Qi, Y.; Rhim, R. H.; Sun, G. F.; Weinert, M.

    2011-03-01

    Combing scanning tunneling microscopy using transition-metal (Fe, Cr)-coated W tips and first-principles calculations, we show that the interface of epitaxial graphene/SiC(0001) is a warped graphene layer with periodic inclusions of hexagon-pentagon-heptagon (H5 , 6 , 7) defects. These defects break the six-fold honeycomb symmetry, thereby inducing a gap and two states below EF near the Dirac point. Furthermore, we show that the next graphene layer assumes the perfect honeycomb lattice, but its interaction with the warped interfacial layer modifies the linear dispersion about the Dirac point, leading to parabolic dispersion and an apparent gap of ~ 0.25 eV. These results explain recent angle-resolved photoemission and carbon core-level shift data, and resolve the long-standing issue of the interfacial structure of epitaxial graphene on SiC(0001).

  2. Development of an Equivalent Composite Honeycomb Model: A Finite Element Study

    NASA Astrophysics Data System (ADS)

    Steenackers, G.; Peeters, J.; Ribbens, B.; Vuye, C.

    2016-07-01

    Finite element analysis of complex geometries such as honeycomb composites, brings forth several difficulties. These problems are expressed primarily as high calculation times but also memory issues when solving these models. In order to bypass these issues, the main goal of this research paper is to define an appropriate equivalent model in order to minimize the complexity of the finite element model and thus minimize computation times. A finite element study is conducted on the design and analysis of equivalent layered models, substituting the honeycomb core in sandwich structures. A comparison is made between available equivalent models. An equivalent model with the right set of material property values is defined and benchmarked, consisting of one continuous layer with orthotropic elastic properties based on different available approximate formulas. This way the complex geometry does not need to be created while the model yields sufficiently accurate results.

  3. 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.

  4. 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 ...

  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

  6. 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.

  7. Classification of defects in honeycomb composite structure of helicopter rotor blades

    NASA Astrophysics Data System (ADS)

    Balaskó, M.; Sváb, E.; Molnár, Gy.; Veres, I.

    2005-04-01

    The use of non-destructive testing methods to qualify the state of rotor blades with respect to their expected flight hours, with the aim to extend their lifetime without any risk of breakdown, is an important financial demand. In order to detect the possible defects in the composite structure of Mi-8 and Mi-24 type helicopter rotor blades used by the Hungarian Army, we have performed combined neutron- and X-ray radiography measurements at the Budapest Research Reactor. Several types of defects were detected, analysed and typified. Among the most frequent and important defects observed were cavities, holes and/or cracks in the sealing elements on the interface of the honeycomb structure and the section boarders. Inhomogeneities of the resin materials (resin-rich or starved areas) at the core-honeycomb surfaces proved to be an other important point. Defects were detected at the adhesive filling, and water percolation was visualized at the sealing interfaces of the honeycomb sections. Corrosion effects, and metal inclusions have also been detected.

  8. Local feedback control of light honeycomb panels.

    PubMed

    Hong, Chinsuk; Elliott, Stephen J

    2007-01-01

    This paper summarizes theoretical and experimental work on the feedback control of sound radiation from honeycomb panels using piezoceramic actuators. It is motivated by the problem of sound transmission in aircraft, specifically the active control of trim panels. Trim panels are generally honeycomb structures designed to meet the design requirement of low weight and high stiffness. They are resiliently mounted to the fuselage for the passive reduction of noise transmission. Local coupling of the closely spaced sensor and actuator was observed experimentally and modeled using a single degree of freedom system. The effect of the local coupling was to roll off the response between the actuator and sensor at high frequencies, so that a feedback control system can have high gain margins. Unfortunately, only relatively poor global performance is then achieved because of localization of reduction around the actuator. This localization prompts the investigation of a multichannel active control system. Globalized reduction was predicted using a model of 12-channel direct velocity feedback control. The multichannel system, however, does not appear to yield a significant improvement in the performance because of decreased gain margin. PMID:17297778

  9. Lattice Defects in the Kitaev Honeycomb Model.

    PubMed

    Brennan, John; Vala, Jiří

    2016-05-19

    The Kitaev honeycomb lattice system is an important model of topological materials whose phase diagram exhibits both abelian and non-abelian topological phases. The latter, a so-called Ising phase, is related to topological superconductors. Its quasiparticle excitations, which are formed by Majorana fermions attached to vortices, show non-abelian fractional statistics and are known as Ising anyons. We investigate dislocation defects in the Ising phase of the Kitaev honeycomb model. After introducing them to the system, we accordingly generalize our solution of this model to the situation with the defects. The important part of this effort is developing an appropriate Jordan-Wigner fermionization procedure. It is expected that the presence of defects manifests itself by the formation of fermionic zero-energy modes around the defect end points. We numerically confirm this expectation and further investigate properties of these modes. The computational potential of our technique is demonstrated for both diagonalization and dynamical simulations. The latter focuses on the process of fusion of the vortex zero-energy modes with the Majorana fermions attached to the defect. This process simulates fusion of non-abelian Ising anyons. PMID:26886150

  10. 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.

  11. 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.

  12. 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.

  13. Simulation of the honeycomb construction process

    NASA Astrophysics Data System (ADS)

    Yuanzhang, Zhang

    2010-06-01

    The construction process of the honeycomb by bees is an astonishing process. The original structure which the bees built is nothing more than a lot of rough cylinders. But keeping the beeswax semi-flow for a certain time, those rough structures become perfect hexahedral columns. A modified, simplified particle method was used here to simulate the semi-flow state of the material. Although the parameters used here were still rather subjective, the simulation still could demonstrate some behavior of that sort of material like beeswax. And the method that the bees used to build their honey comb, could be an efficient method to imitate when we are trying to manufacture cellular materials.

  14. Numerical simulation of a porous honeycomb burner

    SciTech Connect

    Hackert, C.L.; Elizey, J.L.; Ezekoye, O.A.

    1997-07-01

    A two-dimensional simulation of a honeycomb burner using single step global chemistry is used to investigate the importance of thermal properties and boundary conditions to inert porous burners. Comparisons to available experimental results are made where possible, and a parametric study of the effects of burner properties on the flame is performed. The burner solid emissivity is found to be relatively unimportant to the achievable burning rate and radiant output fraction, so long as it is above a certain minimum value (about 0.3). In contrast, increases in solid conductivity always lead to marked increases in burning rate. The flame is shown to exhibit significant curvature on both a pore scale and burner scale.

  15. Stripe states in photonic honeycomb ribbon

    PubMed Central

    Park, Sul-Ah; Son, Young-Woo; Ahn, Kang-Hun

    2015-01-01

    We reveal new stripe states in deformed hexagonal array of photonic wave guides when the array is terminated to have a ribbon-shaped geometry. Unlike the well-known zero energy edge modes of honeycomb ribbon, the new one-dimensional states are shown to originate from high-energy saddle-shaped photonic bands of the ribbon's two-dimensional counterpart. We find that the strain field deforming the ribbon generates pseudo-electric fields in contrast to pseudo-magnetic fields in other hexagonal crystals. Thus, the stripe states experience Bloch oscillation without any actual electric field so that the spatial distributions of stripes have a singular dependence on the strength of the field. The resulting stripe states are located inside the bulk and their positions depend on their energies.

  16. Optimum Running Condition of Honeycomb Type Rotation Desiccant Device Composed of Polymer Sorbent

    NASA Astrophysics Data System (ADS)

    Kida, Takahisa; Inaba, Hideo; Horibe, Akihiko

    This paper deals with the optimum running conditions of honeycomb rotor composed of new polymer sorbent which was composed of the cross-linked polymer of sodium acrylate. At first, overall mass transfer coefficient of the honeycomb rotor for numerical computation was derived by the experimental results from the model experimental apparatus. Numerical simulations could predict the optimum running conditions of the honeycomb rotor such as the revolution number of the honeycomb rotor against the inflow air velocity and honeycomb length etc.

  17. Honeycomb Betavoltaic Battery for Space Applications

    NASA Astrophysics Data System (ADS)

    Lee, Jin R.; Ulmen, Ben; Miley, George H.

    2008-01-01

    Radioisotopic batteries offer advantages relative to conventional chemical batteries for applications requiring a long lifetime with minimum maintenance. Thus, thermoelectric type cells fueled with Pu have been used extensively on NASA space missions. The design for a small beta battery using nickel-63 (Ni-63) and a vacuum direct collection method is described here. A honeycomb nickel wire structure is employed to achieve bi-directional direct collection by seeding Ni-63 onto honeycomb shaped wires that will provide structural support as well. The battery design is intended to power low power electronics and distribute power needs in space probes as well as space colonies. Ni-63 is chosen as the source emitter because it has a long half-life and ease of manufacturing. The use of vacuum is especially well mated to space use; hence, vacuum insulation is employed to gain a higher efficiency than prior beta batteries with a dielectric insulator. A unique voltage down-converter is incorporated to efficiently reduce the inherent output voltage from 17.4 kV to ~17.4 V. This converter operates like a ``reverse'' Marx circuit where capacitor charging occurs in series but the discharge is in parallel. The reference battery module described here is about 100 cm×100 cm×218 cm and has a power of ~10 W with a conversion efficiency of ~15.8%. These modules can be stacked for higher powers and are very attractive for various applications in space colonization due to their long life (half-life for Ni-63~100 yrs) and low maintenance.

  18. 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.

  19. Propogation loss with frequency of ultrasound guided waves in a composite metal-honeycomb structure

    NASA Astrophysics Data System (ADS)

    Saxena, Indu F.; Baid, Harsh K.; Guzman, Narciso; Kempen, Lothar U.; Mal, Ajit

    2009-05-01

    Non-destructive testing of critical structural components is time consuming, while necessary for maintaining safe operation. Large aerospace structures, such as the vertical stabilizers of aircraft undergo inspection at regular intervals for damage diagnostics. However, conventional techniques for damage detection and identification before repair can be scheduled are conducted off-line and therefore can take weeks. The use of guided ultrasound waves is being investigated to expedite damage detection in composites. We measure the frequency dependent loss of ultrasonic guided waves for a structure comprising a boron-nitride composite skin sandwiching an aluminum honeycomb. A wide range of ultrasound frequencies propagate as measured using PZTs, with the lowest attenuation observed about 200-250 kHz. These measurements are confirmed using optical fiber Bragg grating arrays used as ultrasound transducers.

  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

  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. 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.

  4. Effective Dirac Hamiltonian for anisotropic honeycomb lattices: Optical properties

    NASA Astrophysics Data System (ADS)

    Oliva-Leyva, M.; Naumis, Gerardo G.

    2016-01-01

    We derive the low-energy Hamiltonian for a honeycomb lattice with anisotropy in the hopping parameters. Taking the reported Dirac Hamiltonian for the anisotropic honeycomb lattice, we obtain its optical conductivity tensor and its transmittance for normal incidence of linearly polarized light. Also, we characterize its dichroic character due to the anisotropic optical absorption. As an application of our general findings, which reproduce the previous case of uniformly strained graphene, we study the optical properties of graphene under a nonmechanical distortion.

  5. 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.

  6. 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)

  7. Aluminum Hydroxide

    MedlinePlus

    ... penicillamine (Cuprimine, Depen), prednisone (Deltasone, Orasone), products containing iron, tetracycline (Sumycin, Tetracap, and others), ticlopidine (Ticlid), and vitamins.be aware that aluminum hydroxide may interfere with other medicines, making them less effective. Take your other medications 1 ...

  8. Edge states in polariton honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Milićević, 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 π and π* 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.

  9. Hypervelocity impact response of honeycomb sandwich panels

    NASA Astrophysics Data System (ADS)

    Schonberg, William; Schäfer, Frank; Putzar, Robin

    2010-02-01

    Man-made orbital poses a serious threat to spacecraft that are launched to operate in Earth orbit because it can strike such spacecraft at very high velocities and consequently damage mission-critical systems. This paper describes the findings of a study whose objective was to develop a system of empirical equations that can be used to predict the trajectories and spread of the debris clouds that exit the rear facesheet following a high speed perforating impact of a honeycomb sandwich panel (HC/SP). These equations are based on a database containing the results of nearly 400 tests from 13 previously published papers and reports. Overall the correlation coefficient values for the various regression equations obtained are fairly reasonable, and range from near 60% to well above 90%. This indicates that the chosen forms of the equations are a good fit to the data, and that they are capable of picking up most of the variations in the data that result from changes in test conditions. These equations can now be used to estimate the amount of mass in a debris cloud if an HC/SP is perforated by a high speed impact, where this mass will travel, and what spacecraft components will be impacted by it. This information can then be fed into a risk assessment code to calculate the probability of spacecraft failure under a prescribed set of impact conditions.

  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. 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

  12. 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

  13. Identical band gaps in structurally re-entrant honeycombs.

    PubMed

    Zhu, Zhu-Wei; Deng, Zi-Chen

    2016-08-01

    Structurally re-entrant honeycomb is a sort of artificial lattice material, characterized by star-like unit cells with re-entrant topology, as well as a high connectivity that the number of folded sheets jointing at each vertex is at least six. In-plane elastic wave propagation in this highly connected honeycomb is investigated through the application of the finite element method in conjunction with the Bloch's theorem. Attention is devoted to exploring the band characteristics of two lattice configurations with different star-like unit cells, defined as structurally square re-entrant honeycomb (SSRH) and structurally hexagonal re-entrant honeycomb (SHRH), respectively. Identical band gaps involving their locations and widths, interestingly, are present in the two considered configurations, attributed to the resonance of the sketch folded sheets, the basic component elements for SSRH and SHRH. In addition, the concept of heuristic models is implemented to elucidate the underlying physics of the identical gaps. The phenomenon of the identical bandgaps is not only beneficial for people to further explore the band characteristics of lattice materials, but also provides the structurally re-entrant honeycombs as potential host structures for the design of lattice-based metamaterials of interest for elastic wave control. PMID:27586722

  14. Aluminum alloy

    NASA Technical Reports Server (NTRS)

    Blackburn, Linda B. (Inventor); Starke, Edgar A., Jr. (Inventor)

    1989-01-01

    This invention relates to aluminum alloys, particularly to aluminum-copper-lithium alloys containing at least about 0.1 percent by weight of indium as an essential component, which are suitable for applications in aircraft and aerospace vehicles. At least about 0.1 percent by weight of indium is added as an essential component to an alloy which precipitates a T1 phase (Al2CuLi). This addition enhances the nucleation of the precipitate T1 phase, producing a microstructure which provides excellent strength as indicated by Rockwell hardness values and confirmed by standard tensile tests.

  15. Mesoporous aluminum phosphite

    SciTech Connect

    El Haskouri, Jamal; Perez-Cabero, Monica; Guillem, Carmen; Latorre, Julio; Beltran, Aurelio; Beltran, Daniel; Amoros, Pedro

    2009-08-15

    High surface area pure mesoporous aluminum-phosphorus oxide-based derivatives have been synthesized through an S{sup +}I{sup -} surfactant-assisted cooperative mechanism by means of a one-pot preparative procedure from aqueous solution and starting from aluminum atrane complexes and phosphoric and/or phosphorous acids. A soft chemical extraction procedure allows opening the pore system of the parent as-prepared materials by exchanging the surfactant without mesostructure collapse. The nature of the pore wall can be modulated from mesoporous aluminum phosphate (ALPO) up to total incorporation of phosphite entities (mesoporous aluminum phosphite), which results in a gradual evolution of the acidic properties of the final materials. While phosphate groups in ALPO act as network building blocks (bridging Al atoms), the phosphite entities become basically attached to the pore surface, what gives practically empty channels. The mesoporous nature of the final materials is confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM) and N{sub 2} adsorption-desorption isotherms. The materials present regular unimodal pore systems whose order decreases as the phosphite content increases. NMR spectroscopic results confirm the incorporation of oxo-phosphorus entities to the framework of these materials and also provide us useful information concerning the mechanism through which they are formed. - Abstract: TEM image of the mesoporous aluminum phosphite showing the hexagonal disordered pore array that is generated by using surfactant micelles as template. Also a scheme emphasizing the presence of an alumina-rich core and an ALPO-like pore surface is presented.

  16. Modeling and structural analysis of honeycomb structure mirror

    NASA Astrophysics Data System (ADS)

    Li, Yeping

    2012-09-01

    In development of large-scale astronomical telescopes, some promising new technology and method such as honeycomb structure mirrors and silicon carbide mirrors are applied for primary mirrors. Especially in space telescopes, the mirror lightweight design is becoming the key technology and honeycomb structure mirrors are normally required more and more to reduce the cost and increase the feasibility of the telescopes system. In this paper, a parameter FEA model of a two meters honeycomb structure mirror has been built, by using the engineering analysis software ANSYS. Through this model, the structural analysis, thermal deformation analysis and the simulation active correction of low-order frequency aberration by the finite element method have been presented.

  17. Manufacture of large glass honeycomb mirrors. [for astronomical telescopes

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    The problem of making very large glass mirrors for astronomical telescopes is examined, and the advantages of honeycomb mirrors made of borosilicate glass are discussed. Thermal gradients in the glass that degrade the figure of thick borosilicate mirrors during use can be largely eliminated in a honeycomb structure by internal ventilation (in air) or careful control of the radiation environment (in space). It is expected that ground-based telescopes with honeycomb mirrors will give better images than those with solid mirrors. Materials, techniques, and the experience that has been gained making trial mirrors and test castings as part of a program to develop 8-10-m-diameter lightweight mirrors are discussed.

  18. 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

  19. A first theoretical realization of honeycomb topological magnon insulator.

    PubMed

    Owerre, S A

    2016-09-28

    It has been recently shown that in the Heisenberg (anti)ferromagnet on the honeycomb lattice, the magnons (spin wave quasipacticles) realize a massless two-dimensional (2D) Dirac-like Hamiltonian. It was shown that the Dirac magnon Hamiltonian preserves time-reversal symmetry defined with the sublattice pseudo spins and the Dirac points are robust against magnon-magnon interactions. The Dirac points also occur at nonzero energy. In this paper, we propose a simple realization of nontrivial topology (magnon edge states) in this system. We show that the Dirac points are gapped when the inversion symmetry of the lattice is broken by introducing a next-nearest neighbour Dzyaloshinskii-Moriya (DM) interaction. Thus, the system realizes magnon edge states similar to the Haldane model for quantum anomalous Hall effect in electronic systems. However, in contrast to electronic spin current where dissipation can be very large due to Ohmic heating, noninteracting topological magnons can propagate for a long time without dissipation as magnons are uncharged particles. We observe the same magnon edge states for the XY model on the honeycomb lattice. Remarkably, in this case the model maps to interacting hardcore bosons on the honeycomb lattice. Quantum magnetic systems with nontrivial magnon edge states are called topological magnon insulators. They have been studied theoretically on the kagome lattice and recently observed experimentally on the kagome magnet Cu(1-3, bdc) with three magnon bulk bands. Our results for the honeycomb lattice suggests an experimental procedure to search for honeycomb topological magnon insulators within a class of 2D quantum magnets and ultracold atoms trapped in honeycomb optical lattices. In 3D lattices, Dirac and Weyl points were recently studied theoretically, however, the criteria that give rise to them were not well-understood. We argue that the low-energy Hamiltonian near the Weyl points should break time-reversal symmetry of the pseudo spins

  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

  1. A first theoretical realization of honeycomb topological magnon insulator

    NASA Astrophysics Data System (ADS)

    Owerre, S. A.

    2016-09-01

    It has been recently shown that in the Heisenberg (anti)ferromagnet on the honeycomb lattice, the magnons (spin wave quasipacticles) realize a massless two-dimensional (2D) Dirac-like Hamiltonian. It was shown that the Dirac magnon Hamiltonian preserves time-reversal symmetry defined with the sublattice pseudo spins and the Dirac points are robust against magnon–magnon interactions. The Dirac points also occur at nonzero energy. In this paper, we propose a simple realization of nontrivial topology (magnon edge states) in this system. We show that the Dirac points are gapped when the inversion symmetry of the lattice is broken by introducing a next-nearest neighbour Dzyaloshinskii–Moriya (DM) interaction. Thus, the system realizes magnon edge states similar to the Haldane model for quantum anomalous Hall effect in electronic systems. However, in contrast to electronic spin current where dissipation can be very large due to Ohmic heating, noninteracting topological magnons can propagate for a long time without dissipation as magnons are uncharged particles. We observe the same magnon edge states for the XY model on the honeycomb lattice. Remarkably, in this case the model maps to interacting hardcore bosons on the honeycomb lattice. Quantum magnetic systems with nontrivial magnon edge states are called topological magnon insulators. They have been studied theoretically on the kagome lattice and recently observed experimentally on the kagome magnet Cu(1-3, bdc) with three magnon bulk bands. Our results for the honeycomb lattice suggests an experimental procedure to search for honeycomb topological magnon insulators within a class of 2D quantum magnets and ultracold atoms trapped in honeycomb optical lattices. In 3D lattices, Dirac and Weyl points were recently studied theoretically, however, the criteria that give rise to them were not well-understood. We argue that the low-energy Hamiltonian near the Weyl points should break time-reversal symmetry of the pseudo

  2. 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. γ - TiAl and

  3. Carbon Honeycomb High Capacity Storage for Gaseous and Liquid Species.

    PubMed

    Krainyukova, Nina V; Zubarev, Evgeniy N

    2016-02-01

    We report an exceptionally stable honeycomb carbon allotrope obtained by deposition of vacuum-sublimated graphite. The allotrope structures are derived from our low temperature electron diffraction and electron microscopy data. These structures can be both periodic and random and are built exclusively from sp^{2}-bonded carbon atoms, and may be considered as three-dimensional graphene. They demonstrate high levels of physical absorption of various gases unattainable in other carbon forms such as fullerites or nanotubes. These honeycomb structures can be used not only for storage of various gases and liquids but also as a matrix for new composites. PMID:26894716

  4. Carbon Honeycomb High Capacity Storage for Gaseous and Liquid Species

    NASA Astrophysics Data System (ADS)

    Krainyukova, Nina V.; Zubarev, Evgeniy N.

    2016-02-01

    We report an exceptionally stable honeycomb carbon allotrope obtained by deposition of vacuum-sublimated graphite. The allotrope structures are derived from our low temperature electron diffraction and electron microscopy data. These structures can be both periodic and random and are built exclusively from s p2 -bonded carbon atoms, and may be considered as three-dimensional graphene. They demonstrate high levels of physical absorption of various gases unattainable in other carbon forms such as fullerites or nanotubes. These honeycomb structures can be used not only for storage of various gases and liquids but also as a matrix for new composites.

  5. Chaos in the honeycomb optical-lattice unit cell

    NASA Astrophysics Data System (ADS)

    Porter, Max D.; Reichl, L. E.

    2016-01-01

    Natural and artificial honeycomb lattices are of great interest because the band structure of these lattices, if properly constructed, contains a Dirac point. Such lattices occur naturally in the form of graphene and carbon nanotubes. They have been created in the laboratory in the form of semiconductor 2DEGs, optical lattices, and photonic crystals. We show that, over a wide energy range, gases (of electrons, atoms, or photons) that propagate through these lattices are Lorentz gases and the corresponding classical dynamics is chaotic. Thus honeycomb lattices are also of interest for understanding eigenstate thermalization and the conductor-insulator transition due to dynamic Anderson localization.

  6. Dirac lines in the superconducting hyper-honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Bouhon, Adrien; Black-Schaffer, Annica

    Motivated by the recent discovery of the hyper-honeycomb β-Li2IrO3 studied in the context of Kitaev spin liquids, we investigate the possibility to realize superconductivity in the hyper-honeycomb lattice. Based on a t-J model we discuss the effect of the band structure and spin-orbit coupling on the most stable superconducting state. Using group theory we construct all symmetry allowed superconducting states and show that we naturally get Dirac line nodes protected by the non-symmorphic symmetries.

  7. The actuated performance of multi-layer piezoelectric actuator in active vibration control of honeycomb sandwich panel

    NASA Astrophysics Data System (ADS)

    Luo, Yajun; Xie, Shilin; Zhang, Xinong

    2008-11-01

    This paper discusses the use of the multi-layer piezoelectric actuator (MPA) in the active vibration control of the honeycomb sandwich panel (HSP). A literature overview of the available works is first presented. And the main motivation using the MPA in the AVC of HSP is discussed. Then, the honeycomb core is in advance treated as an orthotropic plate. The governing equations of the system are derived by the Hamilton principle on the basis of both displacement and transverse tress assumptions. The formulations of the actuation force/moment are obtained and indicate that the actuation force/moment are two four-order polynomial function of the piezoelectric layers number. Finally, active control experiments of a cantilever honeycomb sandwich panel (CHSP) are performed using the MPA. The control law of proportional velocity feedback is adopted in the experiments. These experiments include the resonant vibration control and the sinusoidal swept of the control system at the case of different piezoelectric layers number. The results show that the MPA can effectively control the vibration of the high damping HSP, and the control performance per voltage by the proposed actuator can be improved significantly through increasing the piezoelectric patch number. Consequently, the MPA exhibits better actuation capability than that with only single layer.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Hollow needle used to cut metal honeycomb structures

    NASA Technical Reports Server (NTRS)

    Gregg, E. A.

    1966-01-01

    Hollow needle tool cuts metal honeycomb structures without damaging adjacent material. The hollow needle combines an electrostatic discharge and a stream of oxygen at a common point to effect rapid, accurate metal cutting. The tool design can be varied to use the hollow needle principle for cutting a variety of shapes.

  13. Honeycomb and triangular domain wall networks in heteroepitaxial systems.

    PubMed

    Elder, K R; Chen, Z; Elder, K L M; Hirvonen, P; Mkhonta, S K; Ying, S-C; Granato, E; Huang, Zhi-Feng; Ala-Nissila, T

    2016-05-01

    A comprehensive study is presented for the influence of misfit strain, adhesion strength, and lattice symmetry on the complex Moiré patterns that form in ultrathin films of honeycomb symmetry adsorbed on compact triangular or honeycomb substrates. The method used is based on a complex Ginzburg-Landau model of the film that incorporates elastic strain energy and dislocations. The results indicate that different symmetries of the heteroepitaxial systems lead to distinct types of domain wall networks and phase transitions among various surface Moiré patterns and superstructures. More specifically, the results show a dramatic difference between the phase diagrams that emerge when a honeycomb film is adsorbed on substrates of honeycomb versus triangular symmetry. It is also shown that in the small deformation limit, the complex Ginzburg-Landau model reduces to a two-dimensional sine-Gordon free energy form. This free energy can be solved exactly for one dimensional patterns and reveals the role of domains walls and their crossings in determining the nature of the phase diagrams. PMID:27155643

  14. Titanium honeycomb structure. [for supersonic aircraft wing structure

    NASA Technical Reports Server (NTRS)

    Davis, R. A.; Elrod, S. D.; Lovell, D. T.

    1972-01-01

    A brazed titanium honeycomb sandwich system for supersonic transport wing cover panels provides the most efficient structure spanwise, chordwise, and loadwise. Flutter testing shows that high wing stiffness is most efficient in a sandwich structure. This structure also provides good thermal insulation if liquid fuel is carried in direct contact with the wing structure in integral fuel tanks.

  15. Honeycomb and triangular domain wall networks in heteroepitaxial systems

    NASA Astrophysics Data System (ADS)

    Elder, K. R.; Chen, Z.; Elder, K. L. M.; Hirvonen, P.; Mkhonta, S. K.; Ying, S.-C.; Granato, E.; Huang, Zhi-Feng; Ala-Nissila, T.

    2016-05-01

    A comprehensive study is presented for the influence of misfit strain, adhesion strength, and lattice symmetry on the complex Moiré patterns that form in ultrathin films of honeycomb symmetry adsorbed on compact triangular or honeycomb substrates. The method used is based on a complex Ginzburg-Landau model of the film that incorporates elastic strain energy and dislocations. The results indicate that different symmetries of the heteroepitaxial systems lead to distinct types of domain wall networks and phase transitions among various surface Moiré patterns and superstructures. More specifically, the results show a dramatic difference between the phase diagrams that emerge when a honeycomb film is adsorbed on substrates of honeycomb versus triangular symmetry. It is also shown that in the small deformation limit, the complex Ginzburg-Landau model reduces to a two-dimensional sine-Gordon free energy form. This free energy can be solved exactly for one dimensional patterns and reveals the role of domains walls and their crossings in determining the nature of the phase diagrams.

  16. 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.

  17. 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.

  18. Honeycombing on CT; its definition, pathologic correlation, and future direction of its diagnosis.

    PubMed

    Johkoh, Takeshi; Sakai, Fumikazu; Noma, Satoshi; Akira, Masanori; Fujimoto, Kiminori; Watadani, Takeyuki; Sugiyama, Yukihiko

    2014-01-01

    Honeycombing on CT is the clue for the diagnosis of usual interstitial pneumonia (UIP) and its hallmark. According to the ATS-ERS-JRS-ALAT 2010 guideline, the patients with honeycombing on CT can be diagnosed as UIP without surgical biopsy. On CT scans, it is defined as clustered cystic airspaces, typically of comparable diameters of the order of 3-10mm, which are usually subpleural and have well-defined walls. Pathologically, honeycombing consists of both collapsing of multiple fibrotic alveoli and dilation of alveolar duct and lumen Although the definition of honeycombing seems to be strict, recognition of honeycombing on CT is various among each observer Because typical honeycombing is frequently observed in the patients with UIP, we should judge clustered cysts as honeycombing when a diagnosis of UIP is suspected. PMID:23806532

  19. Quantum Hall effects in a non-Abelian honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Li, Ling; Hao, Ningning; Liu, Guocai; Bai, Zhiming; Li, Zai-Dong; Chen, Shu; Liu, W. M.

    2015-12-01

    We study the tunable quantum Hall effects in a non-Abelian honeycomb optical lattice which is a multi-Dirac-point system. We find that the quantum Hall effects present different features with the change in relative strengths of several perturbations. Namely, the quantum spin Hall effect can be induced by gauge-field-dressed next-nearest-neighbor hopping, which, together with a Zeeman field, can induce the quantum anomalous Hall effect characterized by different Chern numbers. Furthermore, we find that the edge states of the multi-Dirac-point system represent very different features for different boundary geometries, in contrast with the generic two-Dirac-point system. Our study extends the borders of the field of quantum Hall effects in a honeycomb optical lattice with multivalley degrees of freedom.

  20. Fatigue and impact properties of metal honeycomb sandwich panel

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

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

  1. The Colored Hofstadter Butterfly for the Honeycomb Lattice

    NASA Astrophysics Data System (ADS)

    Agazzi, A.; Eckmann, J.-P.; Graf, G. M.

    2014-08-01

    We rely on a recent method for determining edge spectra and we use it to compute the Chern numbers for Hofstadter models on the honeycomb lattice having rational magnetic flux per unit cell. Based on the bulk-edge correspondence, the Chern number is given as the winding number of an eigenvector of a transfer matrix, as a function of the quasi-momentum . This method is computationally efficient (of order in the resolution of the desired image). It also shows that for the honeycomb lattice the solution for for flux in the -th gap conforms with the Diophantine equation , which determines . A window such as , or possibly shifted, provides a natural further condition for , which however turns out not to be met. Based on extensive numerical calculations, we conjecture that the solution conforms with the relaxed condition.

  2. Total heat transport data for plastic honeycomb-type structures

    SciTech Connect

    Platzer, W.J. )

    1992-11-01

    The total heat transport within honeycomb-type structures consists mainly of radiation and conduction heat transport, as convection is usually suppressed. For surface emissivities larger than 0.7, independent mode analysis may be used, and a splitting of the measured total heat transport into parts is possible. Only a few parameters used in simple modeling equations are needed to describe the heat transport in this approximation. They have been obtained by fitting the functions to experimental results and are presented in tabular form for 11 different materials. The thickness and temperature dependence is included in the results. The presented data may be used as input parameters either for simple calculations in an independent mode analysis (IMA) or for a dependent mode analysis (DMA). Thus even selective flat-plate honeycomb collectors may be modeled reliably.

  3. Adsorption-induced strain of a nanoscale silicon honeycomb

    NASA Astrophysics Data System (ADS)

    Grosman, A.; Puibasset, J.; Rolley, E.

    2015-03-01

    We report on systematic measurements of both adsorption and anisotropic mechanical deformations of mesoporous silicon, using heptane at room temperature. Porous Si obtained from highly doped (100) Si can be thought of as a nanoscale random honeycomb with pores parallel to the [001] axis. We show that strains ε\\parallel and ε\\bot measured along and transversely to the pore axis exhibit a hysteretic behavior as a function of the fluid pressure, which is due to the hysteresis in fluid adsorption. The pressure dependence of the strains together with the independent measurement of the transverse stress, allows us to determine the biaxial transverse modulus and to estimate the longitudinal Young's modulus of porous Si. We argue that the value of these constants implies that Young's modulus of the 6 nm thick walls of the honeycomb is about 5 times smaller than that of bulk silicon, striking evidence of finite-size effects.

  4. Mechanical-Acoustic Multi-Objective Optimization of Honeycomb Plate

    NASA Astrophysics Data System (ADS)

    Li, Wang-Ying; Yang, Xiong-Wei; Li, Yue-Ming

    At present, optimal design against noise caused by vibrating structures is often formulated with the objective of minimizing sound power or sound pressure. In this paper, a mechanical and acoustic multi-objective optimization method is proposed aimed at minimizing static, dynamic and acoustic response of a honeycomb sandwich panel under given mass constraint. The multi-objective is defined as a weighted sum of static deflection, vibration response and sound power from the norm method. The static and dynamic responses are calculated using FEM and sound power radiated by structures is calculated using discrete Rayleigh integral. The sensitivities of static, dynamic and acoustic response are formulated to improve efficiency by the adjoint method. Numerical examples on the honeycomb plate are considered, which indicate that the proposed method can improve acoustical property without weakening mechanical property.

  5. Layer Anti-Ferromagnetism on Bilayer Honeycomb Lattice

    PubMed Central

    Tao, Hong-Shuai; Chen, Yao-Hua; Lin, Heng-Fu; Liu, Hai-Di; Liu, Wu-Ming

    2014-01-01

    Bilayer honeycomb lattice, with inter-layer tunneling energy, has a parabolic dispersion relation, and the inter-layer hopping can cause the charge imbalance between two sublattices. Here, we investigate the metal-insulator and magnetic phase transitions on the strongly correlated bilayer honeycomb lattice by cellular dynamical mean-field theory combined with continuous time quantum Monte Carlo method. The procedures of magnetic spontaneous symmetry breaking on dimer and non-dimer sites are different, causing a novel phase transition between normal anti-ferromagnet and layer anti-ferromagnet. The whole phase diagrams about the magnetism, temperature, interaction and inter-layer hopping are obtained. Finally, we propose an experimental protocol to observe these phenomena in future optical lattice experiments. PMID:24947369

  6. Charge dynamics in doped Mott insulators on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Ma, Xixiao; Lan, Yu; Qin, Ling; Feng, Shiping

    2016-03-01

    Within the framework of the fermion-spin theory, the charge transport in the doped Mott insulators on a honeycomb lattice is studied by taking into account the pseudogap effect. It is shown that the conductivity spectrum in the low-doped regime is separated by the pseudogap into a low-energy non-Drude peak followed by a broad mid-infrared band. However, the decrease of the pseudogap with the increase of doping leads to a shift of the position of the mid-infrared band towards the low-energy non-Drude peak, and then the low-energy Drude behavior recovers in the high-doped regime. The combined results of both the doped honeycomb-lattice and square-lattice Mott insulators indicate that the two-component conductivity induced by the pseudogap is a universal feature in the doped Mott insulators.

  7. Ultrasonic waveguide transducer for high temperature testing of ceramic honeycomb

    NASA Astrophysics Data System (ADS)

    Wang, N.; An, C. P.; Nickerson, S. T.; Gunasekaran, N.; Shi, Z.

    2013-01-01

    This paper describes the development of a practical ultrasonic waveguide transducer designed for in situ material property characterization of ceramic honeycomb at high temperatures (>1200°C) and under fast thermal cycles (>1000°C/min). The low thermal conductivity MACOR waveguide allows the use of conventional transducer (max temp. 50°C) at one end and guides ultrasonic waves into the high temperature region where the characterization is carried out. The impact of time, temperature, and heating/cooling rates on the material behavior was studied. It was demonstrated that the same transducer could also be used for in-situ crack detection during the thermal shock testing of ceramic honeycomb.

  8. 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.

  9. 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.

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

    PubMed Central

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

    2014-01-01

    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

  11. Spin-orbital quantum liquid on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Corboz, Philippe

    2013-03-01

    The symmetric Kugel-Khomskii can be seen as a minimal model describing the interactions between spin and orbital degrees of freedom in transition-metal oxides with orbital degeneracy, and it is equivalent to the SU(4) Heisenberg model of four-color fermionic atoms. We present simulation results for this model on various two-dimensional lattices obtained with infinite projected-entangled pair states (iPEPS), an efficient variational tensor-network ansatz for two dimensional wave functions in the thermodynamic limit. This approach can be seen as a two-dimensional generalization of matrix product states - the underlying ansatz of the density matrix renormalization group method. We find a rich variety of exotic phases: while on the square and checkerboard lattices the ground state exhibits dimer-Néel order and plaquette order, respectively, quantum fluctuations on the honeycomb lattice destroy any order, giving rise to a spin-orbital liquid. Our results are supported from flavor-wave theory and exact diagonalization. Furthermore, the properties of the spin-orbital liquid state on the honeycomb lattice are accurately accounted for by a projected variational wave-function based on the pi-flux state of fermions on the honeycomb lattice at 1/4-filling. In that state, correlations are algebraic because of the presence of a Dirac point at the Fermi level, suggesting that the ground state is an algebraic spin-orbital liquid. This model provides a good starting point to understand the recently discovered spin-orbital liquid behavior of Ba3CuSb2O9. The present results also suggest to choose optical lattices with honeycomb geometry in the search for quantum liquids in ultra-cold four-color fermionic atoms. We acknowledge the financial support from the Swiss National Science Foundation.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. A honeycomb composite of mollusca shell matrix and calcium alginate.

    PubMed

    You, Hua-jian; Li, Jin; Zhou, Chan; Liu, Bin; Zhang, Yao-guang

    2016-03-01

    A honeycomb composite is useful to carry cells for application in bone, cartilage, skin, and soft tissue regenerative therapies. To fabricate a composite, and expand the application of mollusca shells as well as improve preparing methods of calcium alginate in tissue engineering research, Anodonta woodiana shell powder was mixed with sodium alginate at varying mass ratios to obtain a gel mixture. The mixture was frozen and treated with dilute hydrochloric acid to generate a shell matrix/calcium alginate composite. Calcium carbonate served as the control. The composite was transplanted subcutaneously into rats. At 7, 14, 42, and 70 days after transplantation, frozen sections were stained with hematoxylin and eosin, followed by DAPI, β-actin, and collagen type-I immunofluorescence staining, and observed using laser confocal microscopy. The composite featured a honeycomb structure. The control and composite samples displayed significantly different mechanical properties. The water absorption rate of the composite and control group were respectively 205-496% and 417-586%. The composite (mass ratio of 5:5) showed good biological safety over a 70-day period; the subcutaneous structure of the samples was maintained and the degradation rate was lower than that of the control samples. Freezing the gel mixture afforded control over chemical reaction rates. Given these results, the composite is a promising honeycomb scaffold for tissue engineering. PMID:26700239

  17. 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.

  18. Design for aluminum recycling

    SciTech Connect

    Not Available

    1993-10-01

    This article describes the increasing use of aluminum in automobiles and the need to recycle to benefit further growth of aluminum applications by assuring an economical, high-quality source of metal. The article emphasizes that coordination of material specifications among designers can raise aluminum scrap value and facilitate recycling. Applications of aluminum in automobile construction are discussed.

  19. 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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Hou, Jing-Min; Chen, Wei

    2015-12-01

    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.

  2. 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

  3. Water Vapor Desorption Characteristics of Honeycomb Type Sorption Element Composed of Organic Sorbent

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Kida, Takahisa; Horibe, Akihiko; Kaneda, Makoto; Okamoto, Tamio; Seo, Jeong-Kyun

    This paper describes the water vapor desorption characteristics of honeycomb shape type sorbent element containing new organic sorbent of the bridged complex of sodium polyacrylate. The transient experiments in which the dry air was passed into the honeycomb type sorbent element sorbed water vapor were carried out under various conditions of air velocity, temperature, relative humidity and honeycomb length. The obtained data for desorption process were compared with those for sorption process. Finally, Sherwood number of mass transfer of the organic sorbent for desorption process was derived in terms of Reynolds number, modified Stefan number and non-dimensional honeycomb length.

  4. 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.

  5. Characterizatin of ultrafine aluminum nanoparticles

    SciTech Connect

    Sandstrom, M. M.; Jorgensen, B. S.; Mang, J. T.; Smith, B. L.; Son, S. F.

    2004-01-01

    Aluminum nanopowders with particle sizes ranging from {approx}25 nm to 80 nm were characterized by a variety of methods. We present and compare the results from common powder characterization techniques including transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), BET gas adsorption surface area analysis, thermogravimetric analysis (TGA), photon correlation spectroscopy (PCS), and low angle laser light scattering (LALLS). Aluminum nanoparticles consist of an aluminum core with an aluminum oxide coating. HRTEM measurements of both the particle diameter and oxide layer thickness tend to be larger than those obtained from BET and TGA. LALLS measurements show a large degree of particle agglomeration in solution; therefore, primary particle sizes could not be determined. Furthermore, results from small-angle scattering techniques (SAS), including small-angle neutron (SANS) and x-ray (SAXS) scattering are presented and show excellent agreement with the BET, TGA, and HRTEM. The suite of analytical techniques presented in this paper can be used as a powerful tool in the characterization of many types of nanosized powders.

  6. Spring back of infinite honeycomb sheets beyond plastic deformation

    NASA Astrophysics Data System (ADS)

    Bonfanti, A.; Bhaskar, A.

    2015-02-01

    Cellular structures are promising for applications where high stiffness and strength are required with the minimal use of material. They are often used in applications where the plastic deformation plays an important role, such as those involving crashworthiness, energy absorption, and stents. The elastic analysis of a honeycomb sheet has been carried out in the past [1]. The present analysis extends this classical work in the elasto-plastic regime. Recoil analysis due to elastic recovery is absent from the published literature. This work aims to develop an analytical model to calculate the spring back for a simplified case, that of an infinite honeycomb sheet. An elastic-perfectly plastic material model is assumed. The recoil for a clamped beam with a load and moment applied at the free edge is analytically calculated first. This is carried out by relating the stress distribution of the cross section to the final deformed shape. The part corresponding to the elastic contribution is subsequently subtracted in order to obtain the final configuration after the external load is removed. This simple elasto-plastic analysis is then incorporated into the analysis of an infinite sheet made of uniform hexagonal cells. The translational symmetry of the lattice is exploited along with the analysis of a beam under tip loading through to plastic stage and recoil. The final shape of the struts upon the removal of the remote stress is completely determined by the plastic deformation which cannot be recovered. The expression for the beam thus obtained is then used to build an analytical model for an infinite honeycomb sheet loaded in both directions.

  7. Half-metallicity in 2D organometallic honeycomb frameworks.

    PubMed

    Sun, Hao; Li, Bin; Zhao, Jin

    2016-10-26

    Half-metallic materials with a high Curie temperature (T C) have many potential applications in spintronics. Magnetic metal free two-dimensional (2D) half-metallic materials with a honeycomb structure contain graphene-like Dirac bands with π orbitals and show excellent aspects in transport properties. In this article, by investigating a series of 2D organometallic frameworks with a honeycomb structure using first principles calculations, we study the origin of forming half-metallicity in this kind of 2D organometallic framework. Our analysis shows that charge transfer and covalent bonding are two crucial factors in the formation of half-metallicity in organometallic frameworks. (i) Sufficient charge transfer from metal atoms to the molecules is essential to form the magnetic centers. (ii) These magnetic centers need to be connected through covalent bonding, which guarantee the strong ferromagnetic (FM) coupling. As examples, the organometallic frameworks composed by (1,3,5)-benzenetricarbonitrile (TCB) molecules with noble metals (Au, Ag, Cu) show half-metallic properties with T C as high as 325 K. In these organometallic frameworks, the strong electronegative cyano-groups (CN groups) drive the charge transfer from metal atoms to the TCB molecules, forming the local magnetic centers. These magnetic centers experience strong FM coupling through the d-p covalent bonding. We propose that most of the 2D organometallic frameworks composed by molecule-CN-noble metal honeycomb structures contain similar half metallicity. This is verified by replacing TCB molecules with other organic molecules. Although the TCB-noble metal organometallic framework has not yet been synthesized, we believe the development of synthesizing techniques and facility will enable the realization of them. Our study provides new insight into the 2D half-metallic material design for the potential applications in nanotechnology. PMID:27541575

  8. 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.

  9. 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 / ν, γ / ν and β / ν were found. Their values indicate that the stationary state of the antiferromagnetic majority voter model belongs to the Ising model universality class.

  10. Geometric Frustration of Colloidal Dimers on a Honeycomb Magnetic Lattice

    NASA Astrophysics Data System (ADS)

    Tierno, Pietro

    2016-01-01

    We study the phase behavior and the collective dynamics of interacting paramagnetic colloids assembled above a honeycomb lattice of triangular shaped magnetic minima. A frustrated colloidal molecular crystal is realized when filling these potential minima with exactly two particles per pinning site. External in-plane rotating fields are used to anneal the system into different phases, including long range ordered stripes, random fully packed loops, labyrinth and disordered states. At a higher amplitude of the annealing field, the dimer lattice displays a two-step melting transition where the initially immobile dimers perform first localized rotations and later break up by exchanging particles across consecutive lattice minima.

  11. Electron and phonon properties and gas storage in carbon honeycombs

    NASA Astrophysics Data System (ADS)

    Gao, Yan; Chen, Yuanping; Zhong, Chengyong; Zhang, Zhongwei; Xie, Yuee; Zhang, Shengbai

    2016-06-01

    A new kind of three-dimensional carbon allotrope, termed carbon honeycomb (CHC), has recently been synthesized [PRL 116, 055501 (2016)]. Based on the experimental results, a family of graphene networks has been constructed, and their electronic and phonon properties are studied by various theoretical approaches. All networks are porous metals with two types of electron transport channels along the honeycomb axis and they are isolated from each other: one type of channel originates from the orbital interactions of the carbon zigzag chains and is topologically protected, while the other type of channel is from the straight lines of the carbon atoms that link the zigzag chains and is topologically trivial. The velocity of the electrons can reach ~106 m s-1. Phonon transport in these allotropes is strongly anisotropic, and the thermal conductivities can be very low when compared with graphite by at least a factor of 15. Our calculations further indicate that these porous carbon networks possess high storage capacity for gaseous atoms and molecules in agreement with the experiments.A new kind of three-dimensional carbon allotrope, termed carbon honeycomb (CHC), has recently been synthesized [PRL 116, 055501 (2016)]. Based on the experimental results, a family of graphene networks has been constructed, and their electronic and phonon properties are studied by various theoretical approaches. All networks are porous metals with two types of electron transport channels along the honeycomb axis and they are isolated from each other: one type of channel originates from the orbital interactions of the carbon zigzag chains and is topologically protected, while the other type of channel is from the straight lines of the carbon atoms that link the zigzag chains and is topologically trivial. The velocity of the electrons can reach ~106 m s-1. Phonon transport in these allotropes is strongly anisotropic, and the thermal conductivities can be very low when compared with graphite by

  12. Fully packed loop model on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Blöte, H. W. J.; Nienhuis, B.

    1994-02-01

    We investigate the O(n) model on the honeycomb lattice, using its loop representation in the limit of full packing. The universal properties, which we calculate by means of finite-size scaling and transfer-matrix techniques, are different from the branches of O(n) critical behavior known thus far. The conformal anomaly of the model varies between -1 and 2 in the interval 0<=n<=2. The universality class of the model is characterized as a superposition of a low-temperature O(n) phase, and a solid-on-solid model at a temperature independent of n.

  13. Water intrusion in thin-skinned composite honeycomb sandwich structures

    NASA Technical Reports Server (NTRS)

    Jackson, Wade C.; O'Brien, T. Kevin

    1988-01-01

    Thin-skinned composite honeycomb sandwich structures from the trailing edge of the U.S. Army's Apache and Chinook helicopters have been tested to ascertain their susceptibility to water intrusion as well as such intrusions' effects on impact damage and cyclic loading. Minimum-impact and fatigue conditions were determined which would create microcracks sufficiently large to allow the passage of water through the skins; damage sufficient for this to occur was for some skins undetectable under a 40X-magnification optical microscope. Flow rate was a function of moisture content, damage, applied strain, and pressure differences.

  14. Geometric Frustration of Colloidal Dimers on a Honeycomb Magnetic Lattice.

    PubMed

    Tierno, Pietro

    2016-01-22

    We study the phase behavior and the collective dynamics of interacting paramagnetic colloids assembled above a honeycomb lattice of triangular shaped magnetic minima. A frustrated colloidal molecular crystal is realized when filling these potential minima with exactly two particles per pinning site. External in-plane rotating fields are used to anneal the system into different phases, including long range ordered stripes, random fully packed loops, labyrinth and disordered states. At a higher amplitude of the annealing field, the dimer lattice displays a two-step melting transition where the initially immobile dimers perform first localized rotations and later break up by exchanging particles across consecutive lattice minima. PMID:26849619

  15. 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.

  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. Assessment of a novel neutron tomography instrument and other nondestructive technologies for the characterization of degradation in honeycomb composites

    NASA Astrophysics Data System (ADS)

    Hungler, P. C.

    The feasibility of developing a nondestructive evaluation technique (NDE) or combination of techniques capable of characterizing degradation in honeycomb composites was investigated. To enable the determination of the exact location of water ingress inside a honeycomb composite structure, a novel neutron tomography instrument (NTI) was designed and developed at RMC. The system represents the only NTI available in Canada and allows a range of objects to be investigated including honeycomb coupons and complete CF 188 rudders. In order to produce 3D volumetric reconstructions of sufficient quality to assess the location of water, the system was optimized in terms of optics, spatial resolution and signal-to-noise ratio (SNR). An imaging test object was designed to enable the quantitative measurement of the spatial resolution in 2D images and 3D reconstructions, filling a gap in the current neutron imaging standards. Several noise reduction filters were applied to 2D and 3D images produced by the NTI, which improved the spatial resolution and SNR. Appropriate coupons that were purposely degraded to represent honeycomb composites subjected to water ingress were designed, constructed and tested. To produce coupons with different degrees of degradation in the skin to core bond, varying numbers of freeze-thaw cycles were used. Destructive flat-wise tension tests were then performed to evaluate the coupons and the results showed a strong first-order linear decay relationship between the number of freeze-thaw cycles and the filet bond strength. The method developed to reliably degrade the filet bond, provides a more appropriate degradation mechanism compared to other available methods for producing degraded coupons. The degraded coupons were subsequently inspected using several adapted NDE techniques: neutron tomography, infrared thermography, through-transmission ultrasonics and acoustic bond testing. Neutron tomography was capable of detailing the exact location of water in

  18. 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.

  19. 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.

  20. 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

  1. Biodegradable honeycomb-patterned film composed of poly(lactic acid) and dioleoylphosphatidylethanolamine.

    PubMed

    Fukuhira, Yukako; Kitazono, Eiichi; Hayashi, Takami; Kaneko, Hiroaki; Tanaka, Masaru; Shimomura, Masatsugu; Sumi, Yoshihiko

    2006-03-01

    Honeycomb-patterned films have been reported to be useful for scaffolds of cell culture in tissue engineering. In the present study, we investigated a new compound, dioleoylphosphatidylethanolamine (DOPE), a naturally derived phospholipid having unsaturated fatty acid moieties, as a surfactant for fabricating honeycomb-patterned poly(d,l-lactide) (PLA) film. Only DOPE among commercially available phospholipids was useful as a surfactant, and it showed good solubility in PLA/chloroform solution and an excellent property for fabricating honeycomb-patterned film (the concentration of DOPE was from 0.2% to 20% by weight based on the weight of PLA). The pore size of the honeycomb was uniform, and all pores were interconnected with each other. The contact angle of water on the honeycomb-patterned film was affected by the amount of DOPE. Time-of-flight secondary ion mass spectrometer (TOF-SIMS) data suggested that DOPE was concentrated on the surface of the honeycomb-patterned film. To investigate cell proliferation and adhesion on the honeycomb-patterned film, NIH3T3 fibroblast cells were cultured on the film. The NIH3T3 cells adhered well on the honeycomb-patterned PLA film with DOPE (PLA-DOPE) and showed good cell proliferation compared to that on honeycomb-patterned PLA film fabricated with a copolymer (CAP) of dodecylacrylamide and omega-carboxyhexylacrylamide (PLA-CAP). These results suggest that the honeycomb-patterned PLA-DOPE can be applicable as a scaffold for cells with better profiles in comparison with PLA-CAP. PMID:16293301

  2. 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.

  3. Iridium containing honeycomb Delafossites by topotactic cation exchange.

    PubMed

    Roudebush, John H; Ross, K A; Cava, R J

    2016-06-01

    We report the structure and magnetic properties of two new iridium-based honeycomb Delafossite compounds, Cu3NaIr2O6 and Cu3LiIr2O6, formed by a topotactic cation exchange reaction. The starting materials Na2IrO3 and Li2IrO3, which are based on layers of IrO6 octahedra in a honeycomb lattice separated by layers of alkali ions, are transformed to the title compounds by a topotactic exchange reaction through heating with CuCl below 450 °C; higher temperature reactions cause decomposition. The new compounds display dramatically different magnetic behavior from their parent compounds - Cu3NaIr2O6 has a ferromagnetic like magnetic transition at 10 K, while Cu3LiIr2O6 retains the antiferromagnetic transition temperature of its parent compound but displays significantly stronger dominance of antiferromagnetic coupling between spins. These results reveal that a surprising difference in the magnetic interactions between the magnetic Ir ions has been induced by a change in the non-magnetic interlayer species. A combination of neutron and X-ray powder diffraction is used for the structure refinement of Cu3NaIr2O6 and both compounds are compared to their parent materials. PMID:27147423

  4. 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.

  5. Deconfined Criticality in a J - Q model on Honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Pujari, Sumiran; Alet, Fabien; Damle, Kedar

    2013-03-01

    The Deconfined Criticality scenario[1] describes in the context of quantum magnets a generic non-Landau second-order transition between two orders that break different symmetries - antiferromagnetic order that breaks SU (2) symmetry and Valence bond (VB) order breaking lattice translational symmetry. We investigate this physics in the context of a J - Q model[2] on the honeycomb lattice using both T = 0 Projector Quantum Monte Carlo (QMC) and finite- T Stochastic Series Expansion QMC techniques. We find evidence for a continuous transition from different measurements including scaling of Néel and VB order parameters, Binder ratios of staggered magnetization, stiffness and uniform susceptibility. We have indications that this critical point belongs to the same universality class as the one observed on square lattice J - Q model. Our results also suggest that this critical fixed point controlling deconfined critical behaviour remains essentially unchanged even on the honeycomb lattice which allows three-fold hedgehog defects in the Néel order to be present in the continuum description of the critical point.

  6. Electron and phonon properties and gas storage in carbon honeycombs.

    PubMed

    Gao, Yan; Chen, Yuanping; Zhong, Chengyong; Zhang, Zhongwei; Xie, Yuee; Zhang, Shengbai

    2016-07-14

    A new kind of three-dimensional carbon allotrope, termed carbon honeycomb (CHC), has recently been synthesized [PRL 116, 055501 (2016)]. Based on the experimental results, a family of graphene networks has been constructed, and their electronic and phonon properties are studied by various theoretical approaches. All networks are porous metals with two types of electron transport channels along the honeycomb axis and they are isolated from each other: one type of channel originates from the orbital interactions of the carbon zigzag chains and is topologically protected, while the other type of channel is from the straight lines of the carbon atoms that link the zigzag chains and is topologically trivial. The velocity of the electrons can reach ∼10(6) m s(-1). Phonon transport in these allotropes is strongly anisotropic, and the thermal conductivities can be very low when compared with graphite by at least a factor of 15. Our calculations further indicate that these porous carbon networks possess high storage capacity for gaseous atoms and molecules in agreement with the experiments. PMID:27315245

  7. 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.

  8. 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)

  9. Aluminum reference electrode

    DOEpatents

    Sadoway, Donald R.

    1988-01-01

    A stable reference electrode for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na.sub.3 AlF.sub.6, wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution.

  10. Aluminum reference electrode

    DOEpatents

    Sadoway, D.R.

    1988-08-16

    A stable reference electrode is described for use in monitoring and controlling the process of electrolytic reduction of a metal. In the case of Hall cell reduction of aluminum, the reference electrode comprises a pool of molten aluminum and a solution of molten cryolite, Na[sub 3]AlF[sub 6], wherein the electrical connection to the molten aluminum does not contact the highly corrosive molten salt solution. This is accomplished by altering the density of either the aluminum (decreasing the density) or the electrolyte (increasing the density) so that the aluminum floats on top of the molten salt solution. 1 fig.

  11. PROCESS FOR JACKETING A CORE

    DOEpatents

    Last, G.A.

    1960-07-19

    A process is given for enclosing the uranium core of a nuclear fuel element by placing the core in an aluminum cup and closing the open end of the cup over the core. As the metal of the cup is brought together in a weld over the center of the end of the core, it is extruded inwardly as internal projection into a central recess in the core and outwardly as an external projection. Thus oxide inclusions in the weld of the cup are spread out into the internal and external projections and do not interfere with the integrity of the weld.

  12. Directed Self-Assembly of Large Scaffold-free Multicellular Honeycomb Structures

    PubMed Central

    Tejavibulya, Nalin; Youssef, Jacquelyn; Bao, Brian; Ferruccio, Toni-Marie; Morgan, Jeffrey R.

    2011-01-01

    A significant challenge to the field of biofabrication is the rapid construction of large three dimensional (3D) living tissues and organs. Multi-cellular spheroids have been used as building blocks. In this paper, we create large multi-cellular honeycomb building blocks using directed self-assembly, whereby cell-to-cell adhesion, in the context of the shape and obstacles of a micromold, drives the formation of a 3D structure. Computer aided design, rapid prototyping and replica molding were used to fabricate honeycomb-shaped micro-molds. Nonadhesive hydrogels cast from these micro-molds were equilibrated in cell culture medium and seeded with two types of mammalian cells. The cells settled into the honeycomb recess, were unable to attach to the nonadhesive hydrogel and so cell-to-cell adhesion drove the self-assembly of a large multicellular honeycomb within 24 hours. Distinct morphological changes occurred to the honeycomb and its cells indicating the presence of significant cell-mediated tension. Unlike the spheroid, whose size is constrained by a critical diffusion distance needed to maintain cell viability, the overall size of the honeycomb is not limited. The rapid production of the honeycomb building unit, with its multiple rings of high density cells and open lumen spaces, offers interesting new possibilities for biofabrication strategies. PMID:21828905

  13. The Morphology and Functions of Articular Chondrocytes on a Honeycomb-Patterned Surface

    PubMed Central

    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(ɛ-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 μm 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

  14. 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.

  15. Eruption of rhyolite at the Honeycomb Hills, Utah - Cyclical tapping of a zoned silicic magma reservoir

    NASA Astrophysics Data System (ADS)

    Byrd, Bradford J.; Nash, William P.

    1993-08-01

    Results are presented of the a study of preeruptive magma condition at the Honeycomb Hills (Utah) volcanic complex. For this purpose, the physical parameters, chemical variation of the melt phase of the magma, and thermodynamic relations of mineral equilibria in the fallout tephra deposit of the Honeycomb Hills rhyolite were examined, with particular attention given to the pyroclastic deposit and the correlation of fine-scale textural and compositional attributes of the tephra. The observed gradients in crystallinity and compositional trends were used to construct an eruption model illustrating the observed characteristics in each of the three phases of the Honeycomb Hills eruption.

  16. Electroless plating of honeycomb and pincushion polymer films prepared by self-organization.

    PubMed

    Yabu, Hiroshi; Hirai, Yuji; Shimomura, Masatsugu

    2006-11-01

    This report describes the fabrication and electroless plating of regular porous and pincushion-like polymer structures prepared by self-organization. Honeycomb-patterned films were prepared by simple casting of polymer solution under applied humid air and pincushion structures by peeling off the top layer of the former films. Silver-deposited honeycomb-patterned films and pincushion films were obtained by simple electroless plating of the respective original structures. XPS revealed Ag deposition on the honeycomb-patterned film. After thermal decomposition or solvent elution of the template polymer, unique metal mesoscopic structures were obtained. PMID:17073508

  17. Quenched dynamics of superconducting Dirac fermions on honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Lu, Ming; Xie, X. C.; X. C. Xie's group Team

    We study the BCS paring dynamics for the superconducting Dirac fermions on honeycomb lattice after a sudden quench of pairing strength. We observe two distinct phases, one is the synchronized phase with undamped oscillations of paring amplitude; the other phase has the paring amplitude oscillates from positive to negative. The exact phase transition point is given by investigating the integrability of the system. Different from the previous work on normal superconducting fermions, which has three distinct phases, our results shows the absence of the Landau damped phase and over damped phase. Moreover, we present a linear analysis in the weakly quenched regime, showing that in a rather long time scale, the dynamics can be approximated as the periodic oscillation with 2Δ∞ angular frequency along with the logarithmic decay of the pairing amplitude, in contrast of the t - 1 / 2 decay for the normal fermions, namely the Landau damped phase. The presenter's advisor.

  18. Discrete solitons and vortices in anisotropic hexagonal and honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Hoq, Q. E.; Kevrekidis, P. G.; Bishop, A. R.

    2016-02-01

    In the present work, we consider the self-focusing discrete nonlinear Schrödinger equation on hexagonal and honeycomb lattice geometries. Our emphasis is on the study of the effects of anisotropy, motivated by the tunability afforded in recent optical and atomic physics experiments. We find that multi-soliton and discrete vortex states undergo destabilizing bifurcations as the relevant anisotropy control parameter is varied. We quantify these bifurcations by means of explicit analytical calculations of the solutions, as well as of their spectral linearization eigenvalues. Finally, we corroborate the relevant stability picture through direct numerical computations. In the latter, we observe the prototypical manifestation of these instabilities to be the spontaneous rearrangement of the solution, for larger values of the coupling, into localized waveforms typically centered over fewer sites than the original unstable structure. For weak coupling, the instability appears to result in a robust breathing of the relevant waveforms.

  19. Topological phase transition on honeycomb lattice with third neighbor hooping

    NASA Astrophysics Data System (ADS)

    Chen, Yao-Hua; Hung, Hsiang-Hsuan; Ting, C. S.

    2014-03-01

    The topological phases originating in spin-orbital coupling systems have attracted great attention in modern condensed matter physics. Many interesting phenomena have been found in recent theoretical and experimental works, such as the integer and fractional quantum Hall effect, topological band insulator, topological Mott insulator, and topological superconductor. We have investigated the topological phase transition on honeycomb lattice with third neighbor hooping by employing the cellular dynamical mean-field theory combining with the continuous-time Monte Carlo method. The non-trivial topological insulator can be found by observing the spin Chern number directly, and the effects of the third neighbor hopping and interaction are also discussed. Furthermore, we also provide the whole phase diagram for interaction, third neighbor hopping, and temperature. This work is supported by the Texas Center for Superconductivity at the University of Houston and by the Robert A. Welch Foundation under Grant No. E-1146.

  20. Discrete solitons and vortices in anisotropic hexagonal and honeycomb lattices

    DOE PAGESBeta

    Hoq, Q. E.; Kevrekidis, P. G.; Bishop, A. R.

    2016-01-14

    We consider the self-focusing discrete nonlinear Schrödinger equation on hexagonal and honeycomb lattice geometries. Our emphasis is on the study of the effects of anisotropy, motivated by the tunability afforded in recent optical and atomic physics experiments. We find that multi-soliton and discrete vortex states undergo destabilizing bifurcations as the relevant anisotropy control parameter is varied. Furthermore, we quantify these bifurcations by means of explicit analytical calculations of the solutions, as well as of their spectral linearization eigenvalues. Finally, we corroborate the relevant stability picture through direct numerical computations. In the latter, we observe the prototypical manifestation of these instabilitiesmore » to be the spontaneous rearrangement of the solution, for larger values of the coupling, into localized waveforms typically centered over fewer sites than the original unstable structure. In weak coupling, the instability appears to result in a robust breathing of the relevant waveforms.« less

  1. Friction-factor characteristics for narrow channels with honeycomb surfaces

    NASA Technical Reports Server (NTRS)

    Ha, T. W.; Morrison, G. L.; Childs, D. W.

    1992-01-01

    The experimental determination of friction-factors for the flow of air in a narrow channel lined with various honeycomb geometries has been carried out. Test results show that, generally, the friction-factor is nearly constant or slightly decreases as the Reynolds number increases, a characteristic common to turbulent flow in pipes. However, in some test geometries this trend is remarkably different. The friction factor dramatically drops and then rises as the Reynolds number increases. This phenomenon can be characterized as a 'friction-factor jump'. Further investigations of the acoustic spectrum and friction-factor measurements for a broad range of Reynolds numbers indicate that the 'friction-factor jump' phenomenon is accompanied by an onset of a normal mode resonance excited coherent flow fluctuation structure, which occurs at Reynolds number of the order of 10,000. The purpose of this paper is to explain the friction-factor-jump phenomenon and friction-factor characteristics.

  2. Chiral bosonic phases on the Haldane honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Vasić, Ivana; Petrescu, Alexandru; Le Hur, Karyn; Hofstetter, Walter

    2015-03-01

    Recent experiments in ultracold atoms and photonic analogs have reported the implementation of artificial gauge fields in lattice systems, facilitating the realization of topological phases. Motivated by such advances, we investigate the Haldane honeycomb lattice tight-binding model, for bosons with local interactions at the average filling of one boson per site. We analyze the ground-state phase diagram and uncover three distinct phases: a uniform superfluid (SF), a chiral superfluid (CSF), and a plaquette Mott insulator with local current loops (PMI). Nearest-neighbor and next-nearest-neighbor currents distinguish CSF from SF, and the phase transition between them is first order. We apply bosonic dynamical mean-field theory and exact diagonalization to obtain the phase diagram, complementing numerics with calculations of excitation spectra in strong and weak coupling perturbation theory. The characteristic density fluctuations, current correlation functions, and excitation spectra are measurable in ultracold atom experiments.

  3. Chiral Bosonic Phases on the Haldane Honeycomb Lattice

    NASA Astrophysics Data System (ADS)

    Vasic, Ivana; Petrescu, Alexandru; Le Hur, Karyn; Hofstetter, Walter; Collaboration Collaboration

    2015-03-01

    Motivated by its recent realization in an ultracold atom experiment, we investigate the honeycomb lattice tight-binding model introduced by Haldane, for bosons with local interactions at the average filling of one boson per site. We uncover in the ground state phase diagram three phases: a uniform superfluid (SF), a chiral superfluid (CSF) and a plaquette Mott insulator with local current loops (PMI). Nearest-neighbor and next-nearest neighbor currents distinguish CSF from SF, and the phase transition between them is first order. We apply bosonic dynamical mean field theory and exact diagonalization to obtain the zero temperature phase diagram, complementing numerics with calculations of excitation spectra in strong and weak coupling perturbation theory. Furthermore, we explore the possibility of chiral Mott insulating phases at the average filling of one boson every two sites. The characteristic density fluctuations, current correlation functions, and excitation spectra are measurable in ultracold atom experiments.

  4. Topological features of engineered arrays of adsorbates in honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Gonzalez-Arraga, Luis A.; Lado, J. L.; Guinea, Francisco

    2016-09-01

    Hydrogen adatoms are one of the most the promising proposals for the functionalization of graphene. The adatoms induce narrow resonances near the Dirac energy, which lead to the formation of magnetic moments. Furthermore, they also create local lattice distortions which enhance the spin-orbit coupling. The combination of magnetism and spin-orbit coupling allows for a rich variety of phases, some of which have non-trivial topological features. We analyze the interplay between magnetism and spin-orbit coupling in ordered arrays of adsorbates on honeycomb lattice monolayers, and classify the different phases that may arise. We extend our model to consider arrays of adsorbates in graphene-like crystals with stronger intrinsic spin-orbit couplings. We also consider a regime away from half-filling in which the Fermi level is at the bottom of the conduction band, we find a Berry curvature distribution corresponding to a Valley-Hall effect.

  5. Phosphorenes with Non-Honeycomb Structures: A Much Extended Family

    NASA Astrophysics Data System (ADS)

    Wu, Menghao; Fu, Huahua; Zhou, Ling; Yao, Kailun; Zeng, Xiao Cheng; Huazhong University of Science; Technology Team; University of Nebraska-Lincoln Team

    We predict a new class of monolayer phosphorous allotropes, namely, ɛ-P, ζ-P, η-P and θ-P. Distinctly different from the monolayer α-P (black) and previously predicted β-P (Phys. Rev. Lett. 112, 176802 (2014)), γ-P and δ-P (Phys. Rev. Lett. 113, 046804 (2014)) 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 phases, together with 5 hybrid phases, are confirmed stable by first-principles calculations. In particularly, the θ-P is shown to be equally stable as the α-P (black) and more stable than all previously reported phosphorene allotropes. Prediction of nonvolatile ferroelastic switching and structural transformation among different phases under strains points out their potential applications via strain engineering. MHW was supported by start-up fund from Huazhong University of Science and Technology.

  6. 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.

  7. Projective symmetry of partons in Kitaev's honeycomb model

    NASA Astrophysics Data System (ADS)

    Mellado, Paula

    2015-03-01

    Low-energy states of quantum spin liquids are thought to involve partons living in a gauge-field background. We study the spectrum of Majorana fermions of Kitaev's honeycomb model on spherical clusters. The gauge field endows the partons with half-integer orbital angular momenta. As a consequence, the multiplicities reflect not the point-group symmetries of the cluster, but rather its projective symmetries, operations combining physical and gauge transformations. The projective symmetry group of the ground state is the double cover of the point group. We acknowledge Fondecyt under Grant No. 11121397, Conicyt under Grant No. 79112004, and the Simons Foundation (P.M.); the Max Planck Society and the Alexander von Humboldt Foundation (O.P.); and the US DOE Grant No. DE-FG02-08ER46544 (O.T.).

  8. Honeycomb: Visual Analysis of Large Scale Social Networks

    NASA Astrophysics Data System (ADS)

    van Ham, Frank; Schulz, Hans-Jörg; Dimicco, Joan M.

    The rise in the use of social network sites allows us to collect large amounts of user reported data on social structures and analysis of this data could provide useful insights for many of the social sciences. This analysis is typically the domain of Social Network Analysis, and visualization of these structures often proves invaluable in understanding them. However, currently available visual analysis tools are not very well suited to handle the massive scale of this network data, and often resolve to displaying small ego networks or heavily abstracted networks. In this paper, we present Honeycomb, a visualization tool that is able to deal with much larger scale data (with millions of connections), which we illustrate by using a large scale corporate social networking site as an example. Additionally, we introduce a new probability based network metric to guide users to potentially interesting or anomalous patterns and discuss lessons learned during design and implementation.

  9. Aluminum: Recycling of Aluminum Dross/Saltcake

    SciTech Connect

    Blazek, S.

    1999-01-29

    As this NICE3 publication details, the objective of this project is to commercialize the process technology to eliminate all landfill waste associated with black dross and saltcake generated from aluminum recycling in the United States.

  10. Aluminum powder metallurgy processing

    NASA Astrophysics Data System (ADS)

    Flumerfelt, Joel Fredrick

    In recent years, the aluminum powder industry has expanded into non-aerospace applications. However, the alumina and aluminum hydroxide in the surface oxide film on aluminum powder require high cost powder processing routes. A driving force for this research is to broaden the knowledge base about aluminum powder metallurgy to provide ideas for fabricating low cost aluminum powder components. 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). The commercial atomization methods are bench marks of current aluminum powder technology. The GARS process is a laboratory scale inert gas atomization facility. A benefit of using pure aluminum powders is an unambiguous interpretation of the results without considering the effects of alloy elements. 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 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

  11. Antiferromagnetism and Kondo screening on a honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Lin, Heng-Fu; Hong-Shuai, Tao; Guo, Wen-Xiang; Liu, Wu-Ming

    2015-05-01

    Magnetic adatoms in the honeycomb lattice have received tremendous attention due to the interplay between Ruderman-Kittel-Kasuya-Yosida interaction and Kondo coupling leading to very rich physics. Here we study the competition between the antiferromagnetism and Kondo screening of local moments by the conduction electrons on the honeycomb lattice using the determinant quantum Monte Carlo method. While changing the interband hybridization V, we systematically investigate the antiferromagnetic-order state and the Kondo singlet state transition, which is characterized by the behavior of the local moment, antiferromagnetic structure factor, and the short range spin-spin correlation. The evolution of the single particle spectrum are also calculated as a function of hybridization V, we find that the system presents a small gap in the antiferromagnetic-order region and a large gap in the Kondo singlet region in the Fermi level. We also find that the localized and itinerant electrons coupling leads to the midgap states in the conduction band in the Fermi level at very small V. Moreover, the formation of antiferromagnetic order and Kondo singlet are studied as on-site interaction U or temperature T increasing, we have derived the phase diagrams at on-site interaction U (or temperature T) and hybridization V plane. Project supported by the National Key Basic Research Special Foundation of China (Grants Nos. 2011CB921502 and 2012CB821305), the National Natural Science Foundation of China (Grants Nos. 61227902, 61378017, and 11434015), the State Key Laboratory for Quantum Optics and Quantum Optical Devices, China (Grant No. KF201403).

  12. Theoretical Predictions of Freestanding Honeycomb Sheets of Cadmium Chalcogenides

    SciTech Connect

    Zhou, Jia; Huang, Jingsong; Sumpter, Bobby G; Kent, Paul R; Xie, Yu; Terrones Maldonado, Humberto; Smith, Sean C

    2014-01-01

    Two-dimensional (2D) nanocrystals of CdX (X = S, Se, Te) typically grown by colloidal synthesis are coated with organic ligands. Recent experimental work on ZnSe showed that the organic ligands can be removed at elevated temperature, giving a freestanding 2D sheet of ZnSe. In this theoretical work, freestanding single- to few-layer sheets of CdX, each possessing a pseudo honeycomb lattice, are considered by cutting along all possible lattice planes of the bulk zinc blende (ZB) and wurtzite (WZ) phases. Using density functional theory, we have systematically studied their geometric structures, energetics, and electronic properties. A strong surface distortion is found to occur for all of the layered sheets, and yet all of the pseudo honeycomb lattices are preserved, giving unique types of surface corrugations and different electronic properties. The energetics, in combination with phonon mode calculations and molecular dynamics simulations, indicate that the syntheses of these freestanding 2D sheets could be selective, with the single- to few-layer WZ110, WZ100, and ZB110 sheets being favored. Through the GW approximation, it is found that all single-layer sheets have large band gaps falling into the ultraviolet range, while thicker sheets in general have reduced band gaps in the visible and ultraviolet range. On the basis of the present work and the experimental studies on freestanding double-layer sheets of ZnSe, we envision that the freestanding 2D layered sheets of CdX predicted herein are potential synthesis targets, which may offer tunable band gaps depending on their structural features including surface corrugations, stacking motifs, and number of layers.

  13. 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

  14. Managing aluminum phosphide poisonings.

    PubMed

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

    2011-07-01

    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 KMnO(4), 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

  15. Steps toward 8m honeycomb mirror blanks. III - 1.8m honeycomb sandwich blanks cast from borosilicate glass

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    The design, fabrication techniques, and equipment used for producing two 1.8-m honeycomb sandwich blanks, eventually leading to production of 8-m blanks, are reported. The procedure employed 85 cast hexagonal tiles at the bottom section, affixed against flotation by SiC bolts. The two plano concave mirrors are 1.83 m thick, weight 500 kg, and are each designed for 19 supports of astatic-lever type. Both blanks are of high quality and with an adequately low bubble content; one is to be figured to high-precision 0.25-arcsecond images, and is to be tested on the Multiple Mirror Telescope. Construction of a spin-casting facility based on the same principle is being planned for test-fabricating spin-cast mirrors on a smaller scale.

  16. 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.

  17. 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.

  18. Effective optimization and analysis of white LED properties by using nano-honeycomb patterned phosphor film.

    PubMed

    Lin, Huang-Yu; Wang, Sheng-Wen; Lin, Chien-Chung; Tu, Zong-Yi; Lee, Po-Tsung; Chen, Huang-Ming; Kuo, Hao-Chung

    2016-08-22

    This study presents an approach for patterning a polydimethylsiloxane (PDMS) phosphor film with a photonic crystal nano-honeycomb structure on a blue chip package. A phosphor film with a nano-honeycomb structure was patterned and transferred using a nanosphere and used for fabricating remote white light-emitting diodes (w-LEDs). The angular correlated color temperature deviation of the remote phosphor LED could be improved by varying nano-honeycomb structure pitches (450, 750, and 1150 nm). In particular, w-LED samples with excellent color uniformity (ΔCCT ranging from 940 to 440 K) were fabricated from 750-nm w-LED samples with nano-honeycomb-patterned tops. PMID:27557183

  19. BONDING ALUMINUM METALS

    DOEpatents

    Noland, R.A.; Walker, D.E.

    1961-06-13

    A process is given for bonding aluminum to aluminum. Silicon powder is applied to at least one of the two surfaces of the two elements to be bonded, the two elements are assembled and rubbed against each other at room temperature whereby any oxide film is ruptured by the silicon crystals in the interface; thereafter heat and pressure are applied whereby an aluminum-silicon alloy is formed, squeezed out from the interface together with any oxide film, and the elements are bonded.

  20. 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.

  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. Loop-Nodal and Point-Nodal Semimetals in Three-Dimensional Honeycomb Lattices

    NASA Astrophysics Data System (ADS)

    Ezawa, Motohiko

    2016-03-01

    A honeycomb structure has a natural extension to three dimensions. Simple examples are hyperhoneycomb and stripy-honeycomb lattices, which are realized in β -Li2IrO3 and γ -Li2IrO3 , respectively. We propose a wide class of three-dimensional (3D) honeycomb lattices which are loop-nodal semimetals. Their edge states have intriguing properties similar to the two-dimensional honeycomb lattice in spite of a dimensional difference. Partial flat bands emerge at the zigzag or bearded edge of the 3D honeycomb lattice, whose boundary is given by the Fermi loop in the bulk spectrum. On the other hand, perfect flat bands emerge in the zigzag-bearded edge or when the anisotropy is large. The loop-nodal structure is destroyed once staggered potential or antiferromagnetic order is introduced. All these 3D honeycomb lattices become strong topological insulators with the inclusion of the spin-orbit interaction (SOI). Furthermore, point-nodal semimetals may be realized in the presence of both antiferromagnetic order and the SOI. We construct the effective four-band theory with the SOI to understand the physics near the Fermi level, based upon which the density of states and the dc conductivity are calculated.

  3. 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

  4. 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.

  5. Loop-Nodal and Point-Nodal Semimetals in Three-Dimensional Honeycomb Lattices.

    PubMed

    Ezawa, Motohiko

    2016-03-25

    A honeycomb structure has a natural extension to three dimensions. Simple examples are hyperhoneycomb and stripy-honeycomb lattices, which are realized in β-Li_{2}IrO_{3} and γ-Li_{2}IrO_{3}, respectively. We propose a wide class of three-dimensional (3D) honeycomb lattices which are loop-nodal semimetals. Their edge states have intriguing properties similar to the two-dimensional honeycomb lattice in spite of a dimensional difference. Partial flat bands emerge at the zigzag or bearded edge of the 3D honeycomb lattice, whose boundary is given by the Fermi loop in the bulk spectrum. On the other hand, perfect flat bands emerge in the zigzag-bearded edge or when the anisotropy is large. The loop-nodal structure is destroyed once staggered potential or antiferromagnetic order is introduced. All these 3D honeycomb lattices become strong topological insulators with the inclusion of the spin-orbit interaction (SOI). Furthermore, point-nodal semimetals may be realized in the presence of both antiferromagnetic order and the SOI. We construct the effective four-band theory with the SOI to understand the physics near the Fermi level, based upon which the density of states and the dc conductivity are calculated. PMID:27058097

  6. Carbothermic Aluminum Production Using Scrap Aluminum As A Coolant

    DOEpatents

    LaCamera, Alfred F.

    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.

  7. MTBE OXIDATION BY BIFUNCTIONAL ALUMINUM

    EPA Science Inventory

    Bifunctional aluminum, prepared by sulfating zero-valent aluminum with sulfuric acid, has a dual functionality of simultaneously decomposing both reductively- and oxidatively-degradable contaminants. In this work, the use of bifunctional aluminum for the degradation of methyl te...

  8. 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.

  9. 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.

  10. 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.

  11. Aluminum space frame technology

    SciTech Connect

    Birch, S.

    1994-01-01

    This article examines the increased application of aluminum to the construction of automobile frames. The topics of the article include a joint venture between Audi and Alcoa, forms in which aluminum is used, new alloys and construction methods, meeting rigidity and safety levels, manufacturing techniques, the use of extrusions, die casting, joining techniques, and pollution control during manufacturing.

  12. 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…

  13. Cast aluminum denture base.

    PubMed

    Barco, M T; Dembert, M L

    1987-08-01

    The laboratory procedures for a cast aluminum base denture have been presented. If an induction casting machine is not available, the "two-oven technique" works well, provided the casting arm is kept spinning manually for 4 minutes after casting. If laboratory procedures are executed precisely and with care, the aluminum base denture can be cast with good results. PMID:3305884

  14. 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

  15. The aluminum smelting process.

    PubMed

    Kvande, Halvor

    2014-05-01

    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

  16. 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.

  17. 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

  18. A continuum of compass spin models on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Zou, Haiyuan; Liu, Bo; Zhao, Erhai; Liu, W. Vincent

    2016-05-01

    Quantum spin models with spatially dependent interactions, known as compass models, play an important role in the study of frustrated quantum magnetism. One example is the Kitaev model on the honeycomb lattice with spin-liquid ground states. Another example is the geometrically frustrated quantum 120° model whose ground state has not been unambiguously established. To generalize the Kitaev model beyond the exactly solvable limit and connect it with other models, we propose a new model, dubbed ``the tripod model,'' which contains a continuum of compass-type models. It not only unifies paradigmatic spin models, but also enables the study of their quantum phase transitions. We obtain the phase diagram of the tripod model numerically by tensor networks in the thermodynamic limit. We show that the ground state of the quantum 120° model has long-range dimer order. Moreover, we find an extended spin-disordered (spin-liquid) phase between the dimer phase and an antiferromagnetic phase. The unification and solution of a continuum of frustrated spin models as outline here may be useful to exploring new domains of other quantum spin or orbital models.

  19. A continuum of compass spin models on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Zou, Haiyuan; Liu, Bo; Zhao, Erhai; Liu, W. Vincent

    2016-05-01

    Quantum spin models with spatially dependent interactions, known as compass models, play an important role in the study of frustrated quantum magnetism. One example is the Kitaev model on the honeycomb lattice with spin-liquid (SL) ground states and anyonic excitations. Another example is the geometrically frustrated quantum 120° model on the same lattice whose ground state has not been unambiguously established. To generalize the Kitaev model beyond the exactly solvable limit and connect it with other compass models, we propose a new model, dubbed ‘the tripod model’, which contains a continuum of compass-type models. It smoothly interpolates the Ising model, the Kitaev model, and the quantum 120° model by tuning a single parameter {θ }\\prime , the angle between the three legs of a tripod in the spin space. Hence it not only unifies three paradigmatic spin models, but also enables the study of their quantum phase transitions. We obtain the phase diagram of the tripod model numerically by tensor networks in the thermodynamic limit. We show that the ground state of the quantum 120° model has long-range dimer order. Moreover, we find an extended spin-disordered (SL) phase between the dimer phase and an antiferromagnetic phase. The unification and solution of a continuum of frustrated spin models as outline here may be useful to exploring new domains of other quantum spin or orbital models.

  20. Monomer-dimer problem on random planar honeycomb lattice

    SciTech Connect

    Ren, Haizhen; 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.

  1. Proximate Kitaev quantum spin liquid behaviour in a honeycomb magnet

    DOE PAGESBeta

    Banerjee, A.; Bridges, C. A.; Yan, J. -Q.; Aczel, A. A.; Li, L.; Stone, M. B.; Granroth, G. E.; Lumsden, M. D.; Yiu, Y.; Knolle, J.; et al

    2016-04-04

    Quantum spin liquids (QSLs) are topological states of matter exhibiting remarkable properties such as the capacity to protect quantum information from decoherence. While their featureless ground states have precluded their straightforward experimental identification, excited states are more revealing and particularly interesting due to the emergence of fundamentally new excitations such as Majorana Fermions. Ideal probes of these excitations are inelastic neutron scattering experiments. We report these here for a ruthenium-based material α-RuCl3, continuing a major search (so far concentrated on iridium materials inimical to neutron probes) for realizations of the celebrated Kitaev honeycomb topological QSL. Our measurements confirm the requisitemore » strong spin-orbit coupling and low-temperature magnetic order matching predictions proximate to the QSL. We find stacking faults, inherent to the highly 2D nature of the material, resolve an outstanding puzzle. Crucially, dynamical response measurements above interlayer energy scales are naturally accounted for in terms of deconfinement physics expected for QSLs. Comparing these with recent dynamical calculations involving gauge flux excitations and Majorana fermions of the pure Kitaev model, we propose the excitation spectrum of α-RuCl3 as prime candidate for realization of fractionalized Kitaev physics.« less

  2. Thermal analysis of a 4m honeycomb telescope primary mirror

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Xian, Hao

    2012-09-01

    Thermal characteristics of a 4m class honeycomb telescope primary mirror are presented. A 3 dimensional finite elements model of the primary mirror with the varying ambient air temperature as the boundary conditions is used for the numerical simulations. Every night's air temperature profile has been detected in 2009 in Gaomeigu observatory site. Four typical nights' air temperature profiles in different seasons are chose as the boundary conditions in finite element simulation. Temperature difference between primary mirror's optical surface and ambient air is studied, as well as the axial temperature difference inner the mirror blank and radial temperature difference on the optical surface. Primary mirror seeing phenomenon results from the temperature difference between primary mirror's optical surface and the ambient air is discussed. Thermal deformations due to temperature gradient of the primary mirror are analyzed by the finite element model. Axial thermal deformations on the optical surface are discussed in detail. Thermal deformation would induce the optical surface of primary mirror to distort from the normal shape, and lead to large observation image quality degradation. Primary mirror seeing with the turbulence near the optical surface would introduce wavefront aberration and deteriorate the final observation image. In order to reduce mirror seeing and thermal deformation, it is necessary to design a thermal control system for primary mirror. The thermal and structural analysis result will be valuable in designing primary mirror's thermal control system.

  3. Kondo route to spin inhomogeneities in the honeycomb Kitaev model

    NASA Astrophysics Data System (ADS)

    Das, S. D.; Dhochak, K.; Tripathi, V.

    2016-07-01

    Paramagnetic impurities in a quantum spin liquid give rise to Kondo effects with highly unusual properties. We have studied the effect of locally coupling a paramagnetic impurity with the spin-1/2 honeycomb Kitaev model in its gapless spin-liquid phase. The (impurity) scaling equations are found to be insensitive to the sign of the coupling. The weak and strong coupling fixed points are stable, with the latter corresponding to a noninteracting vacancy and an interacting, spin-1 defect for the antiferromagnetic and ferromagnetic cases, respectively. The ground state in the strong coupling limit in both cases has a nontrivial topology associated with a finite Z2 flux at the impurity site. For the antiferromagnetic case, this result has been obtained straightforwardly owing to the integrability of the Kitaev model with a vacancy. The strong-coupling limit of the ferromagnetic case is, however, nonintegrable, and we address this problem through exact-diagonalization calculations with finite Kitaev fragments. Our exact diagonalization calculations indicate that the weak-to-strong coupling transition and the topological phase transition occur rather close to each other and are possibly coincident. We also find an intriguing similarity between the magnetic response of the defect and the impurity susceptibility in the two-channel Kondo problem.

  4. 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 δ-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.

  5. Proximate Kitaev quantum spin liquid behaviour in a honeycomb magnet.

    PubMed

    Banerjee, A; Bridges, C A; Yan, J-Q; Aczel, A A; Li, L; Stone, M B; Granroth, G E; Lumsden, M D; Yiu, Y; Knolle, J; Bhattacharjee, S; Kovrizhin, D L; Moessner, R; Tennant, D A; Mandrus, D G; Nagler, S E

    2016-07-01

    Quantum spin liquids (QSLs) are topological states of matter exhibiting remarkable properties such as the capacity to protect quantum information from decoherence. Whereas their featureless ground states have precluded their straightforward experimental identification, excited states are more revealing and particularly interesting owing to the emergence of fundamentally new excitations such as Majorana fermions. Ideal probes of these excitations are inelastic neutron scattering experiments. These we report here for a ruthenium-based material, α-RuCl3, continuing a major search (so far concentrated on iridium materials) for realizations of the celebrated Kitaev honeycomb topological QSL. Our measurements confirm the requisite strong spin-orbit coupling and low-temperature magnetic order matching predictions proximate to the QSL. We find stacking faults, inherent to the highly two-dimensional nature of the material, resolve an outstanding puzzle. Crucially, dynamical response measurements above interlayer energy scales are naturally accounted for in terms of deconfinement physics expected for QSLs. Comparing these with recent dynamical calculations involving gauge flux excitations and Majorana fermions of the pure Kitaev model, we propose the excitation spectrum of α-RuCl3 as a prime candidate for fractionalized Kitaev physics. PMID:27043779

  6. Monomer-dimer problem on random planar honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Ren, Haizhen; Zhang, Fuji; Qian, Jianguo

    2014-02-01

    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.

  7. 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.

  8. 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.

  9. The honeycomb terrain on the Hellas basin floor, Mars: A case for salt or ice diapirism

    NASA Astrophysics Data System (ADS)

    Bernhardt, H.; Reiss, D.; Hiesinger, H.; Ivanov, M. A.

    2016-04-01

    We present quantitative plausibility studies of potential formation mechanisms for the "honeycomb" terrain on the northwestern Hellas basin floor. The honeycomb terrain is a unique landscape of ~10.5 × 5 km wide, mostly cell-shaped depressions that are arranged in a regular, dense pattern covering ~36,000 km2. We argue against the honeycombs being (peri)glacial landforms (till rings, iceberg imprints, and thermokarst) or the result of igneous diapirism, as terrestrial analogs do not reproduce their key characteristics. Fossilized impact melt convection cells also appear to be an unsuitable interpretation, as melt solidification should not permit such structures to be retained. We present arguments in favor of salt or ice diapirism as honeycomb formation models. Honeycomb-sized diapirs could be formed by a ~2 km thick salt layer (~72,000 km3 for the entire honeycomb terrain), which might have been derived from the highlands north of Hellas Planitia—an area of abundant chloride signatures and intense snowfall according to ancient Mars climate models. Nearby volcanic activity ~3.8 Ga ago potentially enabled recurring phases of (probably salty) meltwater runoff (as indicated by meandering channels) and might therefore have enabled evaporite deposition in the Hellas basin. Being twice as buoyant as salt, water ice would require an only ~1 km thick layer (i.e., ~36,000 km3) to form honeycomb-sized diapirs, which would be in agreement with a likely ~2 km thick ice stability zone beneath the Hellas basin floor. However, it would remain an open question as to why we find only one such ice diapir landscape on Mars.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. 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

  16. 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.

  17. Detection of disbonds in a honeycomb composite structure using guided waves

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

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

  18. A Technique to Determine Billet Core Charge Weight for P/M Fuel Tubes

    SciTech Connect

    Peacock, H.B.

    2001-07-02

    The core length in an extruded tube depends on the weight of powder in the billet core. In the past, the amount of aluminum powder needed to give a specified core length was determined empirically. This report gives a technique for calculating the weight of aluminum powder for the P/M core. An equation has been derived which can be used to determine the amount of aluminum needed for P/M billet core charge weights. Good agreement was obtained when compared to Mark 22 tube extrusion data. From the calculated charge weight, the elastomeric bag can be designed and made to compact the U3O8-Al core.

  19. Oxidation dynamics of aluminum nanorods

    SciTech Connect

    Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

    2015-02-23

    Aluminum nanorods (Al-NRs) are promising fuels for pyrotechnics due to the high contact areas with oxidizers, but their oxidation mechanisms are largely unknown. Here, reactive molecular dynamics simulations are performed to study thermally initiated burning of oxide-coated Al-NRs with different diameters (D = 26, 36, and 46 nm) in oxygen environment. We found that thinner Al-NRs burn faster due to the larger surface-to-volume ratio. The reaction initiates with the dissolution of the alumina shell into the molten Al core to generate heat. This is followed by the incorporation of environmental oxygen atoms into the resulting Al-rich shell, thereby accelerating the heat release. These results reveal an unexpectedly active role of the alumina shell as a “nanoreactor” for oxidation.

  20. Oxidation dynamics of aluminum nanorods

    NASA Astrophysics Data System (ADS)

    Li, Ying; Kalia, Rajiv K.; Nakano, Aiichiro; Vashishta, Priya

    2015-02-01

    Aluminum nanorods (Al-NRs) are promising fuels for pyrotechnics due to the high contact areas with oxidizers, but their oxidation mechanisms are largely unknown. Here, reactive molecular dynamics simulations are performed to study thermally initiated burning of oxide-coated Al-NRs with different diameters (D = 26, 36, and 46 nm) in oxygen environment. We found that thinner Al-NRs burn faster due to the larger surface-to-volume ratio. The reaction initiates with the dissolution of the alumina shell into the molten Al core to generate heat. This is followed by the incorporation of environmental oxygen atoms into the resulting Al-rich shell, thereby accelerating the heat release. These results reveal an unexpectedly active role of the alumina shell as a "nanoreactor" for oxidation.

  1. 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.

  2. 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.

  3. 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)

  4. CORROSION PROTECTION OF ALUMINUM

    DOEpatents

    Dalrymple, R.S.; Nelson, W.B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred. (D.C.W.)

  5. Corrosion Protection of Aluminum

    DOEpatents

    Dalrymple, R. S.; Nelson, W. B.

    1963-07-01

    Treatment of aluminum-base metal surfaces in an autoclave with an aqueous chromic acid solution of 0.5 to 3% by weight and of pH below 2 for 20 to 50 hrs at 160 to 180 deg C produces an extremely corrosion-resistant aluminum oxidechromium film on the surface. A chromic acid concentration of 1 to 2% and a pH of about 1 are preferred.

  6. Existence of featureless paramagnets on the square and the honeycomb lattices in 2+1 dimensions

    NASA Astrophysics Data System (ADS)

    Jian, Chao-Ming; Zaletel, Michael

    2016-01-01

    The peculiar features of quantum magnetism sometimes forbid the existence of gapped "featureless" paramagnets which are fully symmetric and unfractionalized. The Lieb-Schultz-Mattis theorem is an example of such a constraint, but it is not known what the most general restriction might be. We focus on the existence of featureless paramagnets on the spin-1 square lattice and the spin-1 and spin-1/2 honeycomb lattice with spin rotation and space group symmetries in 2+1 dimensions. Although featureless paramagnet phases are not ruled out by any existing theorem, field theoretic arguments disfavor their existence. Nevertheless, by generalizing the construction of Affleck, Kennedy, Lieb, and Tasaki to a class we call "slave-spin" states, we propose featureless wave functions for these models. The featurelessness of the spin-1 slave-spin states on the square and honeycomb lattice are verified both analytically and numerically, but the status of the spin-1/2 honeycomb state remains unclear.

  7. Optimization and Design of 2d Honeycomb Lattice Photonic Crystal Modulated by Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Guo, Caihong; Zheng, Jihong; Gui, Kun; Zhang, Menghua; Zhuang, Songlin

    2013-12-01

    Photonic crystals (PCs) with infiltrating liquid crystals (LCs) have many potential applications because of their ability to continuously modulate the band-gaps. Using the plane-wave expansion method (PWM), we simulate the band-gap distribution of 2D honeycomb lattice PC with different pillar structures (circle, hexagonal and square pillar) and with different filling ratios, considering both when the LC is used as filling pillar material and semiconductors (Si, Ge) are used in the substrate, and when the semiconductors (Si, Ge) are pillar material and the LC is the substrate. Results show that unlike LC-based triangle lattice PC, optimized honeycomb lattice PC has the ability to generate absolute photonic band-gaps for fabricating optical switches. We provide optimization parameters for LC infiltrating honeycomb lattice PC structure based on simulation results and analysis.

  8. Breaking inversion symmetry in a state-dependent honeycomb lattice: artificial graphene with tunable band gap

    NASA Astrophysics Data System (ADS)

    Weinberg, M.; Staarmann, C.; Ölschläger, C.; Simonet, J.; Sengstock, K.

    2016-06-01

    Here, we present the application of a novel method for controlling the geometry of a state-dependent honeycomb lattice: the energy offset between the two sublattices of the honeycomb structure can be adjusted by rotating the atomic quantization axis. This enables us to continuously tune between a homogeneous graphene-like honeycomb lattice and a triangular lattice and to open an energy gap at the characteristic Dirac points. We probe the symmetry of the lattice with microwave spectroscopy techniques and investigate the behavior of atoms excited to the second energy band. We find a striking influence of the energy gap at the Dirac cones onto the lifetimes of bosonic atoms in the excited band.

  9. 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.

  10. Complete band gaps and deaf bands of triangular and honeycomb water-steel phononic crystals

    NASA Astrophysics Data System (ADS)

    Hsiao, Fu-Li; Khelif, Abdelkrim; Moubchir, Hanane; Choujaa, Abdelkrim; Chen, Chii-Chang; Laude, Vincent

    2007-02-01

    Phononic crystals with triangular and honeycomb lattices are investigated experimentally and theoretically. They are composed of arrays of steel cylinders immersed in water. The measured transmission spectra reveal the existence of complete band gaps but also of deaf bands. Band gaps and deaf bands are identified by comparing band structure computations, obtained by a periodic-boundary finite element method, with transmission simulations, obtained using the finite difference time domain method. The appearance of flat bands and the polarization of the associated eigenmodes is also discussed. Triangular and honeycomb phononic crystals with equal cylinder diameter and smallest spacing are compared. As previously obtained with air-solid phononic crystals, it is found that the first complete band gap opens for the honeycomb lattice but not for the triangular lattice, thanks to symmetry reduction.

  11. Use of aluminum nitride to obtain temperature measurements in a high temperature and high radiation environment

    DOEpatents

    Wernsman, Bernard R.; Blasi, Raymond J.; Tittman, Bernhard R.; Parks, David A.

    2016-04-26

    An aluminum nitride piezoelectric ultrasonic transducer successfully operates at temperatures of up to 1000.degree. C. and fast (>1 MeV) neutron fluencies of more than 10.sup.18 n/cm.sup.2. The transducer comprises a transparent, nitrogen rich aluminum nitride (AlN) crystal wafer that is coupled to an aluminum cylinder for pulse-echo measurements. The transducer has the capability to measure in situ gamma heating within the core of a nuclear reactor.

  12. 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.

  13. Prediction of Quantum Anomalous Hall Insulator in half-fluorinated GaBi Honeycomb

    NASA Astrophysics Data System (ADS)

    Chen, Sung-Ping; Huang, Zhi-Quan; Crisostomo, Christian P.; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    2016-08-01

    Using first-principles electronic structure calculations, we predict half-fluorinated GaBi honeycomb under tensile strain to harbor a quantum anomalous Hall (QAH) insulator phase. We show that this QAH phase is driven by a single inversion in the band structure at the Γ point. Moreover, we have computed the electronic spectrum of a half-fluorinated GaBi nanoribbon with zigzag edges, which shows that only one edge band crosses the Fermi level within the band gap. Our results suggest that half-fluorination of the GaBi honeycomb under tensile strain could provide a new platform for developing novel spintronics devices based on the QAH effect.

  14. Nonlinear excitations in the honeycomb lattice: Beyond the high-symmetry points of the band structure

    NASA Astrophysics Data System (ADS)

    Arévalo, Edward; Morales-Molina, Luis

    2016-05-01

    The interplay between nonlinearity and the band structure of pristine honeycomb lattices is systematically explored. For that purpose, a theory of collective excitations valid for the first Brillouin zone of the lattice is developed. Closed-form expressions of two-dimensional excitations are derived for Bloch wave numbers beyond the high-symmetry points of the band structure. A description of the regions of validity of different nonlinear excitations in the first-Brillouin zone is given. We find that the unbounded nature of these excitations in nonlinear honeycomb latices is a signature of the strong influence of the Dirac cones in other parts of the band structure.

  15. Non-affine fluctuations and the statistics of defect precursors in the planar honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Mitra, Amartya; Ganguly, Saswati; Sengupta, Surajit; Sollich, Peter

    2015-06-01

    Certain localised displacement fluctuations in the planar honeycomb lattice may be identified as precursors to topological defects. We show that these fluctuations are among the most pronounced non-affine distortions of an elemental coarse graining volume of the honeycomb structure at non zero temperatures. We obtain the statistics of these precursor modes in the canonical ensemble, evaluating exactly their single point and two-point spatio-temporal distributions, for a lattice with harmonic nearest neighbour and next near neighbour bonds. As the solid is destabilised by tuning interactions, the precursor fluctuations diverge and correlations become long-lived and long-ranged.

  16. 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.

  17. Mineral resources of the Honeycombs Wilderness Study Area, Washakie County, Wyoming

    SciTech Connect

    Peper, J.D.; Hill, R.H.; Kulik, D.M.; Almquist, C.L.

    1988-01-01

    The Honeycombs Wilderness Study Area in Washakie County, Wyo., has no identified mineral or energy resources. A moderate resource potential exists for oil and gas, for undiscovered subsurface coal in the northeastern and southeastern parts of the study area, and for industrial commodities, sand and gravel, mudstone, and sandstone along the western and northern edges of this study area. The Honeycombs Wilderness Study Area has a low resource potential for uranium and no resource potential for metals other than subsurface titanium or for geothermal resources. The potential for subsurface titanium in placer deposits is unknown in this study area.

  18. 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

  19. 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.

  20. 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...

  1. Bimodal distribution of neon nanobubbles in aluminum

    SciTech Connect

    Dhaka, R. S.; Barman, S. R.

    2009-03-15

    Ne 1s core-level photoelectron spectra from Ne nanobubbles implanted in aluminum exhibit two peaks whose binding energies and relative intensities change with implantation energy, isochronal annealing, and sputtering. These changes in the core-level spectra are manifestations of the nanometer size of the bubbles since the screening of the photohole by the Al conduction electrons depends on the bubble size. Existence of a bimodal depth and size distribution of Ne nanobubbles is demonstrated in this work: smaller bubbles of about 4 A in radius are formed close to the Al(111) surface while the larger sized bubbles of 20 A in radius exist deeper below in the beneath subsurface region. A general relation between the radius of the rare-gas bubbles and their core-level binding energies is established.

  2. 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

  3. Efficacy of Honeycomb TCP-induced Microenvironment on Bone Tissue Regeneration in Craniofacial Area

    PubMed Central

    Watanabe, Satoko; Takabatake, Kiyofumi; Tsujigiwa, Hidetsugu; Watanabe, Toshiyuki; Tokuyama, Eijiro; Ito, Satoshi; Nagatsuka, Hitoshi; Kimata, Yoshihiro

    2016-01-01

    Artificial bone materials that exhibit high biocompatibility have been developed and are being widely used for bone tissue regeneration. However, there are no biomaterials that are minimally invasive and safe. In a previous study, we succeeded in developing honeycomb β-tricalcium phosphate (β-TCP) which has through-and-through holes and is able to mimic the bone microenvironment for bone tissue regeneration. In the present study, we investigated how the difference in hole-diameter of honeycomb β-TCP (hole-diameter: 75, 300, 500, and 1600 μm) influences bone tissue regeneration histologically. Its osteoconductivity was also evaluated by implantation into zygomatic bone defects in rats. The results showed that the maximum bone formation was observed on the β-TCP with hole-diameter 300μm, included bone marrow-like tissue and the pattern of bone tissue formation similar to host bone. Therefore, the results indicated that we could control bone tissue formation by creating a bone microenvironment provided by β-TCP. Also, in zygomatic bone defect model with honeycomb β-TCP, the result showed there was osseous union and the continuity was reproduced between the both edges of resected bone and β-TCP, which indicated the zygomatic bone reproduction fully succeeded. It is thus thought that honeycomb β-TCP may serve as an excellent biomaterial for bone tissue regeneration in the head, neck and face regions, expected in clinical applications. PMID:27279797

  4. Efficacy of Honeycomb TCP-induced Microenvironment on Bone Tissue Regeneration in Craniofacial Area.

    PubMed

    Watanabe, Satoko; Takabatake, Kiyofumi; Tsujigiwa, Hidetsugu; Watanabe, Toshiyuki; Tokuyama, Eijiro; Ito, Satoshi; Nagatsuka, Hitoshi; Kimata, Yoshihiro

    2016-01-01

    Artificial bone materials that exhibit high biocompatibility have been developed and are being widely used for bone tissue regeneration. However, there are no biomaterials that are minimally invasive and safe. In a previous study, we succeeded in developing honeycomb β-tricalcium phosphate (β-TCP) which has through-and-through holes and is able to mimic the bone microenvironment for bone tissue regeneration. In the present study, we investigated how the difference in hole-diameter of honeycomb β-TCP (hole-diameter: 75, 300, 500, and 1600 μm) influences bone tissue regeneration histologically. Its osteoconductivity was also evaluated by implantation into zygomatic bone defects in rats. The results showed that the maximum bone formation was observed on the β-TCP with hole-diameter 300μm, included bone marrow-like tissue and the pattern of bone tissue formation similar to host bone. Therefore, the results indicated that we could control bone tissue formation by creating a bone microenvironment provided by β-TCP. Also, in zygomatic bone defect model with honeycomb β-TCP, the result showed there was osseous union and the continuity was reproduced between the both edges of resected bone and β-TCP, which indicated the zygomatic bone reproduction fully succeeded. It is thus thought that honeycomb β-TCP may serve as an excellent biomaterial for bone tissue regeneration in the head, neck and face regions, expected in clinical applications. PMID:27279797

  5. 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.

  6. Macroscopic Artificial Magnetic Honeycomb Lattice of Thermally Controlled Ultra-Small Bonds

    NASA Astrophysics Data System (ADS)

    Summers, Brock; Dahal, Ashutosh; Debeer-Schitt, Lisa; Gunasekera, Jagath; Singh, Deepak

    The two-dimensional artificial magnetic honeycomb lattice system is evolving into a new research arena to explore a plethora of novel magnetism that are predicted to occur as functions of temperature and magnetic field: a long-range spin ice, spin liquid, an entropy-driven magnetic charge-ordered state involving topological vortex pairs and a spin-order due to the spin chirality. We have created macroscopic samples of artificial magnetic honeycomb lattices of Cobalt and Permalloy having connected ultra-small elements (bonds), with length scales of sub-10 nm to 30 nm, which have never before been possible. The equivalent energy of the resulting systems is 10-100 K and is thus amenable to both temperature- and field-dependent exploration of novel magnetic phenomena. We have performed detailed magnetic and small angle neutron scattering measurements (SANS) on the newly fabricated honeycomb lattice of Permalloy that show the thermal character of the system. Furthermore, the experimental data reveals the onset of magnetic ordered regimes in temperature that are consistent with the predicted novel phase diagram in artificial honeycomb lattice. Research is supported by U.S. Department of Energy, Office of Basic Energy Sciences under Grant No. DE-SC0014461.

  7. Non-destructive inspection of drilled holes in reinforced honeycomb sandwich panels using active thermography

    NASA Astrophysics Data System (ADS)

    Usamentiaga, R.; Venegas, P.; Guerediaga, J.; Vega, L.; López, I.

    2012-11-01

    The aerospace industry is in constant need of ever-more efficient inspection methods for quality control. Product inspection is also essential to maintain the safe operation of aircraft components designed to perform for decades. This paper proposes a method for non-destructive inspection of drilled holes in reinforced honeycomb sandwich panels. Honeycomb sandwich panels are extensively employed in the aerospace industry due to their high strength and stiffness to weight ratios. In order to attach additional structures to them, panels are reinforced by filling honeycomb cells and drilling holes into the reinforced areas. The proposed procedure is designed to detect the position of the holes within the reinforced area and to provide a robust measurement of the distance between each hole and the boundary of the reinforced area. The result is a fast, safe and clean inspection method for drilled holes in reinforced honeycomb sandwich panels that can be used to robustly assess a possible displacement of the hole from the center of the reinforced area, which could have serious consequences. The proposed method is based on active infrared thermography, and uses state of the art methods for infrared image processing, including signal-to-nose ratio enhancement, hole detection and segmentation. Tests and comparison with X-ray inspections indicate that the proposed system meets production needs.

  8. 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.

  9. Topological States in Multi-Orbital Honeycomb Lattices of HgTe Quantum Dots

    NASA Astrophysics Data System (ADS)

    Delerue, Christophe; Beugeling, Wouter; Kalesaki, Efterpi; Niquet, Yann-Michel; Vanmaekelbergh, Daniel; Morais Smith, Cristiane

    Recent works demonstrate that 2D single-crystalline sheets of semiconductors forming a honeycomb lattice can be synthesized by oriented attachment of semiconductor nanocrystals. Inspired by these results, we have performed atomistic tight-binding calculations of the band structure of CdSe and HgTe sheets with honeycomb nano-geometry. In the case of CdSe, we predict that their conduction band exhibits Dirac cones at two distinct energies. The lowest one has s-orbital character. The bands higher in energy present a Dirac cone and nontrivial flat bands because of their p-orbital character. We show that lattices of HgTe combine the effects of the honeycomb geometry and strong spin-orbit coupling. The conduction bands 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 and a flattened band detached from the others. Honeycomb structures of HgTe constitute a promising platform for the observation of a fractional Chern insulator or a fractional quantum spin Hall phase.

  10. Numerical calculations for Heisenberg ferromagnet on honeycomb lattice using Oguchi’s method

    SciTech Connect

    Mert, Gülistan; Mert, H. Şevki

    2015-03-10

    Magnetic properties such as the magnetization, internal energy and specific heat for Heisenberg ferromagnet with spin - 1/2 on honeycomb lattice are have been calculated using Oguchi’s method. We have found that the magnetic specific heat exhibits two peaks.

  11. 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.

  12. Regeneration of aluminum hydride

    DOEpatents

    Graetz, Jason Allan; Reilly, James J.

    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.

  13. Elevated temperature aluminum alloys

    NASA Technical Reports Server (NTRS)

    Meschter, Peter (Inventor); Lederich, Richard J. (Inventor); O'Neal, James E. (Inventor)

    1989-01-01

    Three aluminum-lithium alloys are provided for high performance aircraft structures and engines. All three alloys contain 3 wt % copper, 2 wt % lithium, 1 wt % magnesium, and 0.2 wt % zirconium. Alloy 1 has no further alloying elements. Alloy 2 has the addition of 1 wt % iron and 1 wt % nickel. Alloy 3 has the addition of 1.6 wt % chromium to the shared alloy composition of the three alloys. The balance of the three alloys, except for incidentql impurities, is aluminum. These alloys have low densities and improved strengths at temperatures up to 260.degree. C. for long periods of time.

  14. Aluminum Hydroxide and Magnesium Hydroxide

    MedlinePlus

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

  15. On the Fabrication, Characterization and Mechanical Properties of Melt-Stretched Stochastic Honeycombs

    NASA Astrophysics Data System (ADS)

    Hostetter, Megan

    This thesis presents a new type of polypropylene (PP) cellular material fabricated through a simple melt-stretching process. Stochastic honeycombs have an open cell, random honeycomb structure, with webs oriented perpendicular to built-in skins. This process has the advantage that, for example, PP pellets can be turned into a sandwich panel in one step. It was demonstrated that despite the randomness in the web structure, the out-of-plane compressive strength of stochastic honeycombs was repeatable, and exceeded that of commercial PP foams and was comparable to commercial PP honeycombs. The key material properties required to produce an this architecture were shown to be a high melt strength and a high viscosity, branched polymer. The viscosity was shown to affect the total length of the webs in cross-section and the relative partitioning of material through the skin, transition region and webs. Web thickness was affected by the areal density of the polymer during fabrication. Mechanical testing methods were adapted from ASTM standards for honeycombs, and the fabrication method was advanced from a manual to a machine controlled process. Stochastic honeycombs were shown to buckle elastically, plastically, and fracture after the peak strength. Elastic and plastic buckling were dominant at lower densities, and plastic buckling and fracture at higher densities. A thin-plate buckling model for the strength of stochastic honeycombs was developed and verified experimentally. The crystallinity of the polymer affected the tensile strength and stiffness, having a linear effect on the buckling strength. The architecture was composed of webs bound on both sides and webs bound on one side and free on the other. A greater fraction of bound webs increased the strength of the structure in the buckling model. A fabrication study showed that melt-stretching the polymer at higher strain rates increased the connectivity and fraction of bound webs. Additionally, higher density led to a

  16. PROCESS FOR REMOVING ALUMINUM COATINGS

    DOEpatents

    Flox, J.

    1959-07-01

    A process is presented for removing aluminum jackets or cans from uranium slugs. This is accomplished by immersing the aluminum coated uranium slugs in an aqueous solution of 9 to 20% sodium hydroxide and 35 to 12% sodium nitrate to selectively dissolve the aluminum coating, the amount of solution being such as to obtain a molar ratio of sodium hydroxide to aluminum of at least

  17. Composite Cores

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Spang & Company's new configuration of converter transformer cores is a composite of gapped and ungapped cores assembled together in concentric relationship. The net effect of the composite design is to combine the protection from saturation offered by the gapped core with the lower magnetizing requirement of the ungapped core. The uncut core functions under normal operating conditions and the cut core takes over during abnormal operation to prevent power surges and their potentially destructive effect on transistors. Principal customers are aerospace and defense manufacturers. Cores also have applicability in commercial products where precise power regulation is required, as in the power supplies for large mainframe computers.

  18. 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.

  19. 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...

  20. 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.

  1. 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

  2. Aluminum battery alloys

    DOEpatents

    Thompson, David S.; Scott, Darwin H.

    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.

  3. 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....

  4. 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...

  5. Aluminum-ferricyanide battery

    SciTech Connect

    Marsh, C.; Licht, S.L.

    1993-11-29

    A battery capable of producing high current densities with high charge capacity is described which includes an aluminum anode, a ferricyanide electrolyte and a second electrode capable of reducing ferricyanide electrolyte which is either dissolved in an alkaline solution or alkaline seawater solution. The performance of the battery is enhanced by high temperature and high electrolyte flow rates.

  6. 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.

  7. Fluxless aluminum brazing

    DOEpatents

    Werner, W.J.

    1974-01-01

    This invention relates to a fluxless brazing alloy for use in forming brazed composites made from members of aluminum and its alloys. The brazing alloy consists of 35-55% Al, 10--20% Si, 25-60% Ge; 65-88% Al, 2-20% Si, 2--18% In; 65--80% Al, 15-- 25% Si, 5- 15% Y. (0fficial Gazette)

  8. 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.

  9. REMOVAL OF ALUMINUM COATINGS

    DOEpatents

    Peterson, J.H.

    1959-08-25

    A process is presented for dissolving aluminum jackets from uranium fuel elements without attack of the uranium in a boiling nitric acid-mercuric nitrate solution containing up to 50% by weight of nitrtc acid and mercuric nitrate in a concentration of between 0.05 and 1% by weight.

  10. Building an aluminum car

    SciTech Connect

    Ashley, S.

    1994-05-01

    This article examines the increasing use of aluminum in automobiles to decrease weight and consequently increase fuel economy. The topics of the article include federal fuel economy goals, the development of optimum body structure and manufacturing techniques, comparison with steel, cost of materials, weight reduction and recycling of materials.

  11. Evolution of a honeycomb network of precipitates in a hot-rolled commercial Mg-Y-Nd-Zr alloy

    NASA Astrophysics Data System (ADS)

    Choudhuri, D.; Meher, S.; Nag, S.; Dendge, N.; Hwang, J. Y.; Banerjee, R.

    2013-07-01

    Coupled processes of dynamic recovery and precipitation, occurring during hot-rolling and subsequent aging, lead to the formation of a unique honeycomb network of precipitates in commercial Mg-Y-Nd-Zr or WE43 alloy. The honeycomb network is developed on the (0 0 0 1)Mg basal planes and consisted of fine Nd-rich β 1 platelets lying on all three ? planes presumably decorating recovery-generated dislocation subcell boundaries. Three variants of β 1 platelets are connected by Y-rich ? precipitates at the nodes of the hexagonal honeycomb network.

  12. Preparation and characterization of morph-genetic aluminum nitride/carbon composites from filter paper

    SciTech Connect

    Wang Wei Xue Tao; Jin Zhihao; Qiao Guanjun

    2008-04-01

    Morph-genetic aluminum nitride/carbon composites with cablelike structure were prepared from filter paper template through the surface sol-gel process and carbothermal nitridation reaction. The resulting materials have a hierarchical structure originating from the morphology of cellulose paper. The aluminum nitride/carbon composites have the core-shell microstructure, the core is graphitic carbon, and the shell is aluminum nitride nanocoating formed by carbothermal nitridation reduction of alumina with the interfacial carbon in nitrogen atmosphere. Scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and transmission electron microscope were employed to characterize the structural morphology and phase compositions of the final products.

  13. Quantum molecular dynamics simulations of the oxidation of aluminum-cyclopentadienyl clusters

    NASA Astrophysics Data System (ADS)

    Alnemrat, Sufian; Hooper, Joseph P.

    2014-05-01

    We report Car-Parrinello molecular dynamics simulations of the oxidation of aluminum-cyclopentadienyl clusters currently being considered as novel fuels or energetic materials. These clusters contain a small aluminum core surrounded by a single organic ligand layer. The aromatic cyclopentadienyl ligands form a very strong bond with surface Al atoms, giving rise to a stable organometallic cluster which crystallizes into a low-symmetry solid-state material. Our calculations of an isolated cluster in oxygen show minimal reaction between the ligand and oxygen molecules at simulation temperatures of 300 and 1000 K. Rather, in all cases O2 diffuses through the ligand barrier, splits into atomic oxygen upon contact with the aluminum, and forms an amorphous aluminum oxide core. Loss of aluminum-ligand units, as expected from bond strength calculations, is not observed except following significant oxidation. We present simple metrics to quantitatively compare the steric barrier of the outer ligands that limits the oxidation process.

  14. SOLDERING OF ALUMINUM BASE METALS

    DOEpatents

    Erickson, G.F.

    1958-02-25

    This patent deals with the soldering of aluminum to metals of different types, such as copper, brass, and iron. This is accomplished by heating the aluminum metal to be soldered to slightly above 30 deg C, rubbing a small amount of metallic gallium into the part of the surface to be soldered, whereby an aluminum--gallium alloy forms on the surface, and then heating the aluminum piece to the melting point of lead--tin soft solder, applying lead--tin soft solder to this alloyed surface, and combining the aluminum with the other metal to which it is to be soldered.

  15. Preparation and study of 2-D semiconductors with Dirac type bands due to the honeycomb nanogeometry

    NASA Astrophysics Data System (ADS)

    Kalesaki, E.; Boneschanscher, M. P.; Geuchies, J. J.; Delerue, C.; Morais Smith, C.; Evers, W. H.; Allan, G.; Altantzis, T.; Bals, S.; Vanmaekelbergh, D.

    2014-03-01

    The interest in 2-dimensional systems with a honeycomb lattice and related Dirac-­type electronic bands has exceeded the prototype graphene1. Currently, 2-­dimensional atomic2,3 and nanoscale4-­8 systems are extensively investigated in the search for materials with novel electronic properties that can be tailored by geometry. The immediate question that arises is how to fabricate 2-­D semiconductors that have a honeycomb nanogeometry, and as a consequence of that, display a Dirac-­type band structure? Here, we show that atomically coherent honeycomb superlattices of rocksalt (PbSe, PbTe) and zincblende (CdSe, CdTe) semiconductors can be obtained by nanocrystal self-­assembly and facet-­to-­facet atomic bonding, and subsequent cation exchange. We present a extended structural analysis of atomically coherent 2-­D honeycomb structures that were recently obtained with self-assembly and facet-­to-­facet bonding9. We show that this process may in principle lead to three different types of honeycomb structures, one with a graphene type-­, and two others with a silicene-­type structure. Using TEM, electron diffraction, STM and GISAXS it is convincingly shown that the structures are from the silicene-­type. In the second part of this work, we describe the electronic structure of graphene-­type and silicene type honeycomb semiconductors. We present the results of advanced electronic structure calculations using the sp3d5s* atomistic tight-­binding method10. For simplicity, we focus on semiconductors with a simple and single conduction band for the native bulk semiconductor. When the 3-­D geometry is changed into 2-­D honeycomb, a conduction band structure transformation to two types of Dirac cones, one for S-­ and one for P-­orbitals, is observed. The width of the bands depends on the honeycomb period and the coupling between the nanocrystals. Furthermore, there is a dispersionless P-­orbital band, which also forms a landmark of the honeycomb structure

  16. 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.

  17. 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

  18. The use of paper honeycomb for prototype blade construction for small to medium-sized wind driven generators

    NASA Technical Reports Server (NTRS)

    Meyer, H.

    1973-01-01

    Paper honeycomb is used for the construction of conventional, propeller-type, windmill blades. Using fairly simple techniques and conventional power tools, it is possible to shape both simple foils and more complex foils with or without tapered plan forms and with or without varying profiles. A block of honeycomb, in its compressed form, is mounted on a wedge and run through a bandsaw with the table at an appropriate tilt angle. It is the combination of the wedge angle and the table angle that gives the tapered planform and profile shape. Next the honeycomb is expanded on the shaft and jigged to give the desired angles of attack. With the honeycomb fixed in position, the blade is covered with a fine weave fiberglass cloth. Any surface quality can then be achieved with filling and sanding.

  19. Viscoelastic lithography for fabricating self-organizing soft micro-honeycomb structures with ultra-high aspect ratios

    NASA Astrophysics Data System (ADS)

    Jeong, Gi Seok; No, Da Yoon; Lee, Jaeseo; Yoon, Junghyo; Chung, Seok; Lee, Sang-Hoon

    2016-05-01

    High-aspect ratio micro- and nano-structures have been used for the production of a variety of applications. In this paper, we describe a simple and cost-effective approach to fabricate an arrayed microarchitecture with an ultra-high aspect ratio using soft materials. The shapes and sizes of the honeycomb structure can be easily modulated by changing the dimensions and position of the base mould pattern and the pressure. The honeycomb structure is used to prepare a drug delivery patch and a microwell array to form cell spheroids without cell loss. The honeycomb structures prepared using natural ECM (collagen-Matrigel) materials are successfully fabricated. The hepatocytes and endothelial cells are seeded and co-cultured in the ECM-based micro-honeycomb to prepare a 3D liver model successfully mimicking an ultrastructure of liver and providing enhanced liver function.

  20. Honeycomb-alumina supported garnet membrane: Composite electrolyte with low resistance and high strength for lithium metal batteries

    NASA Astrophysics Data System (ADS)

    Liu, Kai; Wang, Chang-An

    2015-05-01

    Li-ion ceramic electrolyte material is considered the key for advanced lithium metal batteries, and garnet-type oxides are promising ceramic electrolyte materials. To disentangle the thinness-strength dilemma in garnet-type Li6.4La3Zr1.4Ta0.6O12 (LLZTO) electrolyte, we designed and successfully synthesized a ceramic-ceramic composite electrolyte, i.e. a honeycomb-Al2O3 pellet supported LLZTO membrane. The honeycomb-Al2O3 pellet acts as a supporter to the thin LLZTO membrane and makes the whole composite electrolyte strong enough, while the straight holes in the Al2O3 supporter can be filled with liquid electrolyte and acts as channels for Li+ transportation. Such a composite design eliminates the concern over the LLZTO membrane's fragility, and keeps its good electrical property.

  1. Honeycomb-like nanofiber based triboelectric nanogenerator using self-assembled electrospun poly(vinylidene fluoride-co-trifluoroethylene) nanofibers

    NASA Astrophysics Data System (ADS)

    Jang, Shin; Kim, Hyounjin; Kim, Yeongjun; Kang, Byung Ju; Oh, Je Hoon

    2016-04-01

    In this study, a honeycomb-like nanofiber based triboelectric nanogenerator (HN-TENG) is presented. In order to fabricate the honeycomb-like nanofiber, we utilized self-assembly of electrospun poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) nanofibers. The honeycomb-like P(VDF-TrFE) nanofiber network was directly produced via electrospinning without any additional processing. The HN-TENG showed a maximum voltage, current, and power density of 160 V, 17 μA, and 1.6 W/m2, respectively. The power density was enhanced more than twofold as compared with a typical flat nanofiber network based TENG due to the large surface area and high surface roughness of the honeycomb structure. Finally, we verified that HN-TENG has the potential to be used for practical applications by driving 100 light emitting diodes and charging capacitors.

  2. Viscoelastic lithography for fabricating self-organizing soft micro-honeycomb structures with ultra-high aspect ratios

    PubMed Central

    Jeong, Gi Seok; No, Da Yoon; Lee, JaeSeo; Yoon, Junghyo; Chung, Seok; Lee, Sang-Hoon

    2016-01-01

    High-aspect ratio micro- and nano-structures have been used for the production of a variety of applications. In this paper, we describe a simple and cost-effective approach to fabricate an arrayed microarchitecture with an ultra-high aspect ratio using soft materials. The shapes and sizes of the honeycomb structure can be easily modulated by changing the dimensions and position of the base mould pattern and the pressure. The honeycomb structure is used to prepare a drug delivery patch and a microwell array to form cell spheroids without cell loss. The honeycomb structures prepared using natural ECM (collagen–Matrigel) materials are successfully fabricated. The hepatocytes and endothelial cells are seeded and co-cultured in the ECM-based micro-honeycomb to prepare a 3D liver model successfully mimicking an ultrastructure of liver and providing enhanced liver function. PMID:27157977

  3. Evidence for coexisting magnetic order in frustrated three-dimensional honeycomb iridates Li2IrO3

    NASA Astrophysics Data System (ADS)

    Breznay, Nicholas; Ruiz, Alejandro; Frano, Alex; Analytis, James

    The search for unconventional magnetism has found a fertile hunting ground in 5d iridium oxide (iridate) materials. The competition between coulomb, spin-orbit, and crystal field energy scales in honeycomb iridates leads to a quantum magnetic system with localized spin-1/2 moments communicating through spin-anisotropic Kitaev exchange interactions. Although early and ongoing work has focused on layered two-dimensional honeycomb compounds such as Na2IrO3 and a 4d analog, RuCl3, recently discovered polytypes of Li2IrO3 take on three-dimensional honeycomb structures. Bulk thermodynamic studies, as well as recent resonant x-ray diffraction and absorption spectroscopy experiments, have uncovered a rich phase diagram for these three-dimensional honeycomb iridates. Low temperature incommensurate and commensurate magnetic orders can be stabilized by tuning the applied magnetic field, displaying a delicate coexistence that signals highly frustrated magnetism.

  4. 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.

  5. 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.

  6. Aluminum permanganate battery

    SciTech Connect

    Marsh, C.; Licht, S.L.

    1993-11-30

    A battery is provided comprising an aluminum anode, an aqueous solution of permanganate as the cathodic species and a second electrode capable of reducing permanganate. Such a battery system is characterized by its high energy density and low polarization losses when operating at high temperatures in a strong caustic electrolyte, i.e., high concentration of hydroxyl ions. A variety of anode and electrocatalyst materials are suitable for the efficient oxidation-reduction process and are elucidated.

  7. 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

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    Sastre, Francisco; Henkel, Malte

    2016-04-01

    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 ω =1.06(9).

  10. Prediction of Quantum Anomalous Hall Insulator in half-fluorinated GaBi Honeycomb.

    PubMed

    Chen, Sung-Ping; Huang, Zhi-Quan; Crisostomo, Christian P; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    2016-01-01

    Using first-principles electronic structure calculations, we predict half-fluorinated GaBi honeycomb under tensile strain to harbor a quantum anomalous Hall (QAH) insulator phase. We show that this QAH phase is driven by a single inversion in the band structure at the Γ point. Moreover, we have computed the electronic spectrum of a half-fluorinated GaBi nanoribbon with zigzag edges, which shows that only one edge band crosses the Fermi level within the band gap. Our results suggest that half-fluorination of the GaBi honeycomb under tensile strain could provide a new platform for developing novel spintronics devices based on the QAH effect. PMID:27507248

  11. Topological Properties of Electrons in Honeycomb Lattice with Detuned Hopping Energy

    NASA Astrophysics Data System (ADS)

    Wu, Long-Hua; Hu, Xiao

    2016-04-01

    Honeycomb lattice can support electronic states exhibiting Dirac energy dispersion, with graphene as the icon. We propose to derive nontrivial topology by grouping six neighboring sites of honeycomb lattice into hexagons and enhancing the inter-hexagon hopping energies over the intra-hexagon ones. We reveal that this manipulation opens a gap in the energy dispersion and drives the system into a topological state. The nontrivial topology is characterized by the index associated with a pseudo time-reversal symmetry emerging from the C6 symmetry of the hopping texture, where the angular momentum of orbitals accommodated on the hexagonal “artificial atoms” behaves as the pseudospin. The size of topological gap is proportional to the hopping-energy difference, which can be larger than typical spin-orbit couplings by orders of magnitude and potentially renders topological electronic transports available at high temperatures.

  12. Topological Properties of Electrons in Honeycomb Lattice with Detuned Hopping Energy

    PubMed Central

    Wu, Long-Hua; Hu, Xiao

    2016-01-01

    Honeycomb lattice can support electronic states exhibiting Dirac energy dispersion, with graphene as the icon. We propose to derive nontrivial topology by grouping six neighboring sites of honeycomb lattice into hexagons and enhancing the inter-hexagon hopping energies over the intra-hexagon ones. We reveal that this manipulation opens a gap in the energy dispersion and drives the system into a topological state. The nontrivial topology is characterized by the index associated with a pseudo time-reversal symmetry emerging from the C6 symmetry of the hopping texture, where the angular momentum of orbitals accommodated on the hexagonal “artificial atoms” behaves as the pseudospin. The size of topological gap is proportional to the hopping-energy difference, which can be larger than typical spin-orbit couplings by orders of magnitude and potentially renders topological electronic transports available at high temperatures. PMID:27076196

  13. Carbon honeycomb grids for advanced lead-acid batteries. Part I: Proof of concept

    NASA Astrophysics Data System (ADS)

    Kirchev, Angel; Kircheva, Nina; Perrin, Marion

    2011-10-01

    The carbon honeycomb grid is proposed as innovative solution for high energy density lead acid battery. The proof of concept is demonstrated, developing grids suitable for the small capacity, scale of valve-regulated lead acid batteries with 2.5-3 Ah plates. The manufacturing of the grids, includes fast, known and simple processes which can be rescaled for mass production with a minimum, investment costs. The most critical process of green composite carbonisation by heating in inert, atmosphere from 200 to 1000 °C takes about 5 h, guaranteeing the low cost of the grids. An AGM-VRLA, cell with prototype positive plate based on the lead-2% tin electroplated carbon honeycomb grid and, conventional negative plates is cycled demonstrating 191 deep cycles. The impedance spectroscopy, measurements indicate the grid performance remains acceptable despite the evolution of the corrosion, processes during the cycling.

  14. The critical surface fugacity of self-avoiding walks on a rotated honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Beaton, Nicholas R.

    2014-02-01

    In a recent paper by Beaton et al, it was proved that a model of self-avoiding walks on the honeycomb lattice, interacting with an impenetrable surface, undergoes an adsorption phase transition when the surface fugacity is 1+\\sqrt{2}. Their proof used a generalization of an identity obtained by Duminil-Copin and Smirnov, and confirmed a conjecture of Batchelor and Yung. We consider a similar model of self-avoiding walk adsorption on the honeycomb lattice, but with the lattice rotated by π/2. For this model there also exists a conjecture for the critical surface fugacity, made in 1998 by Batchelor, Bennett-Wood and Owczarek. Using similar methods to Beaton et al, we prove that this is indeed the critical fugacity.

  15. Prediction of Quantum Anomalous Hall Insulator in Functionalized GaBi Honeycomb

    NASA Astrophysics Data System (ADS)

    Crisostomo, Christian; Chen, Sung-Ping; Huang, Zhi-Quan; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    Using first-principles electronic calculations, we predict functionalized GaBi honeycomb under tensile strain to harbor quantum anomalous hall (QAH) insulating phase. A single band inversion at Γ point was found in spin-polarized band structure of half-fluorinated planar strained GaBi. In order to confirm the topological properties, we evaluated the Chern number (C) and found that C = 1, indicating the presence of QAH phase. Additionally, the same value was also obtained by using hydrogen atoms, instead of fluorine atoms, as the adsorbate in both planar and buckled GaBi. Moreover, the electronic spectrum of a half-fluorinated GaBi nanoribbon with armchair or zigzag edges possess only one edge band crossing the Fermi level within the band gap. Finally, a suitable substrate which could induce the similar effect of half-hydrogenation or half-fluorination on the GaBi honeycomb could be used for spintronic devices.

  16. Prediction of Quantum Anomalous Hall Insulator in half-fluorinated GaBi Honeycomb

    PubMed Central

    Chen, Sung-Ping; Huang, Zhi-Quan; Crisostomo, Christian P.; Hsu, Chia-Hsiu; Chuang, Feng-Chuan; Lin, Hsin; Bansil, Arun

    2016-01-01

    Using first-principles electronic structure calculations, we predict half-fluorinated GaBi honeycomb under tensile strain to harbor a quantum anomalous Hall (QAH) insulator phase. We show that this QAH phase is driven by a single inversion in the band structure at the Γ point. Moreover, we have computed the electronic spectrum of a half-fluorinated GaBi nanoribbon with zigzag edges, which shows that only one edge band crosses the Fermi level within the band gap. Our results suggest that half-fluorination of the GaBi honeycomb under tensile strain could provide a new platform for developing novel spintronics devices based on the QAH effect. PMID:27507248

  17. Self-Assembly of Cubes into 2D Hexagonal and Honeycomb Lattices by Hexapolar Capillary Interactions

    NASA Astrophysics Data System (ADS)

    Soligno, Giuseppe; Dijkstra, Marjolein; van Roij, René

    2016-06-01

    Particles adsorbed at a fluid-fluid interface induce capillary deformations that determine their orientations and generate mutual capillary interactions which drive them to assemble into 2D ordered structures. We numerically calculate, by energy minimization, the capillary deformations induced by adsorbed cubes for various Young's contact angles. First, we show that capillarity is crucial not only for quantitative, but also for qualitative predictions of equilibrium configurations of a single cube. For a Young's contact angle close to 90°, we show that a single-adsorbed cube generates a hexapolar interface deformation with three rises and three depressions. Thanks to the threefold symmetry of this hexapole, strongly directional capillary interactions drive the cubes to self-assemble into hexagonal or graphenelike honeycomb lattices. By a simple free-energy model, we predict a density-temperature phase diagram in which both the honeycomb and hexagonal lattice phases are present as stable states.

  18. A Lightweight Radial Line Slot Antenna with Honeycomb Structure for Space Use

    NASA Astrophysics Data System (ADS)

    Ueda, Hideki; Hirokawa, Jiro; Ando, Makoto; Amano, Osamu; Kamata, Yukio

    A lightweight and high gain planar antenna for space use is realized with radial waveguide slotted array and honeycomb structure with the weight of 1.16kg and the diameter of 920.5mm. The slot coupling is analyzed by method of moments considering the hybrid mode in the multi-layer waveguide structure. The propagation constant of the honeycomb structure is measured and the low-loss property is obtained at the frequency range of 8GHz. The fabricated RLSA is measured and the reflection is around -10dB in 8GHz band. The measured aperture fields agree with the calculation in the radial direction. In the azimuthal direction, on the other hand, the fields show ripples of 6dB and 60 degree. The gain of 35.9dBi with the efficiency of 58.7% is obtained at 8.6GHz.

  19. 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.

  20. Self-Assembly of Cubes into 2D Hexagonal and Honeycomb Lattices by Hexapolar Capillary Interactions.

    PubMed

    Soligno, Giuseppe; Dijkstra, Marjolein; van Roij, René

    2016-06-24

    Particles adsorbed at a fluid-fluid interface induce capillary deformations that determine their orientations and generate mutual capillary interactions which drive them to assemble into 2D ordered structures. We numerically calculate, by energy minimization, the capillary deformations induced by adsorbed cubes for various Young's contact angles. First, we show that capillarity is crucial not only for quantitative, but also for qualitative predictions of equilibrium configurations of a single cube. For a Young's contact angle close to 90°, we show that a single-adsorbed cube generates a hexapolar interface deformation with three rises and three depressions. Thanks to the threefold symmetry of this hexapole, strongly directional capillary interactions drive the cubes to self-assemble into hexagonal or graphenelike honeycomb lattices. By a simple free-energy model, we predict a density-temperature phase diagram in which both the honeycomb and hexagonal lattice phases are present as stable states. PMID:27391753

  1. 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.

  2. Emergent Honeycomb Lattice in LiZn2Mo3O8

    NASA Astrophysics Data System (ADS)

    Flint, Rebecca; Lee, Patrick A.

    2013-11-01

    We introduce the idea of emergent lattices, where a simple lattice decouples into two weakly coupled lattices as a way to stabilize spin liquids. In LiZn2Mo3O8, the disappearance of 2/3 of the spins at low temperatures suggests that its triangular lattice decouples into an emergent honeycomb lattice weakly coupled to the remaining spins, and we suggest several ways to test this proposal. We show that these orphan spins act to stabilize the spin liquid in the J1-J2 honeycomb model and also discuss a possible 3D analogue, Ba2MoYO6 that may form a “depleted fcc lattice.”

  3. Novel thiophene-bearing conjugated microporous polymer honeycomb-like porous spheres with ultrahigh iodine uptake.

    PubMed

    Ren, Feng; Zhu, Zhaoqi; Qian, Xin; Liang, Weidong; Mu, Peng; Sun, Hanxue; Liu, Jiehua; Li, An

    2016-07-28

    Two conjugated microporous polymers containing thiophene-moieties (SCMPs) were obtained by the polymerization of 3,3',5,5'-tetrabromo-2,2'-bithiophene and ethynylbenzene monomers through the palladium-catalyzed Sonogashira-Hagihara crosscoupling reaction. The resulting SCMPs show high thermal stability with a decomposition temperature above 300 °C. Scanning electron microscopy images show that the resulting SCMPs formed as an aggregation composed of micrometer-sized SCMP spheres, in which honeycomb-like porous spheres with penetrated pores on the surface were observed. Taking advantage of such a unique honeycomb-like porous morphology as well as π-conjugated structures, the SCMPs show ultrahigh absorption performance for iodine vapour with an uptake of up to 345 wt% obtained, which is the highest value reported to date for CMPs, thus making the resulting SCMPs ideal absorbent materials for reversible iodine capture to address environmental issues. PMID:27417941

  4. 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

  5. Application of Wave Propagation and Vibration-based Structural Health Monitoring Techniques to Friction Stir Welded Plate and Sandwich Honeycomb Panel

    NASA Astrophysics Data System (ADS)

    Sundararaman, S.; White, J. R.; Adams, D. E.; Jata, K. V.

    2007-03-01

    Wave propagation and vibration-based structural health monitoring methodologies are presented to detect, locate and quantify dent/crack, thermal debond, and corrosion damage in a solid aluminum friction stir weld plate and a sandwich honeycomb thermal protection panel. A wave propagation based method can identify small defects because propagating waves typically consist of small wavelengths while a vibration-based scheme is better equipped to quantify damage over wide areas of large structures. Near-real time online diagnostics is achieved by using localized sensing (wave propagation) and distributed sensing (vibration-based) in an active measurement array. Sensor/actuator arrays have been developed to implement these techniques and portable health management systems have been developed based on the combination of damage detection algorithms, active sensing, and graphical user interfaces. Propagating waves are shown to have a heightened sensitivity to damage located at the anti-nodes of a friction stir wed plate forced by low frequency environmental vibrations. Measurement of the input forcing in the vibration-based method is shown to enable damage quantification.

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

    NASA Technical Reports Server (NTRS)

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

    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.

  7. Effects of interaction in the Hofstadter regime of the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Mishra, Archana; Hassan, S. R.; Shankar, R.

    2016-03-01

    We investigate phases of spinless fermions on the honeycomb lattice with nearest-neighbor interaction in the Hofstadter regime. The interaction induces incompressible nematic and ferrielectric phases with broken translation symmetry. Some of the transitions are accompanied by changes in the Hall conductivity. We study pair correlations and show that the quantum metric, averaged over the Brillouin zone, characterizes the shape of the pair correlation function.

  8. 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.

  9. 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

  10. Frustrated quantum antiferromagnet with third neighbor interactions and single ion anisotropy on the honeycomb lattice

    NASA Astrophysics Data System (ADS)

    Pires, A. S. T.

    2016-08-01

    I study the spin-1 Heisenberg antiferromagnet on the two dimensional honeycomb lattice at zero temperature, with first J1, second J2 and third J3 neighbors exchange interactions and single ion easy plane anisotropy, using the SU(3) Schwinger boson formalism. The phase diagram is shown. The results show the existence of a region in the intermediate frustrated regime where the system does not have quantum magnetic order.

  11. Bosons with Artificial Gauge Fields and Mott Physics on the Honeycomb Lattice

    NASA Astrophysics Data System (ADS)

    Vidanovic, Ivana; Petrescu, Alexandru; Le Hur, Karyn; Hofstetter, Walter

    2014-03-01

    We study bosons in the tight-binding model on the honeycomb lattice introduced by Haldane. We analyze the ground state topology and quasiparticle properties in the Mott phase by applying bosonic dynamical mean field theory, strong-coupling perturbation theory, exact diagonalization and numerical evaluations of sample Hall conductivity. The phase diagram also contains two different superfluid phases. The quasiparticle dynamics, number fluctuations, and local currents are measurable in cold atom experiments.

  12. 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

  13. Extracting aluminum from dross tailings

    NASA Astrophysics Data System (ADS)

    Amer, A. M.

    2002-11-01

    Aluminum dross tailings, an industrial waste, from the Egyptian Aluminium Company (Egyptalum) was used to produce two types of alums: aluminum-sulfate alum [itAl2(SO4)3.12H2O] and ammonium-aluminum alum [ (NH 4)2SO4AL2(SO4)3.24H2O]. This was carried out in two processes. The first process is leaching the impurities using diluted H2SO4 with different solid/liquid ratios at different temperatures to dissolve the impurities present in the starting material in the form of solute sulfates. The second process is the extraction of aluminum (as aluminum sulfate) from the purifi ed aluminum dross tailings thus produced. The effects of temperature, time of reaction, and acid concentration on leaching and extraction processes were studied. The product alums were analyzed using x-ray diffraction and thermal analysis techniques.

  14. 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.

  15. Honeycomb self-assembled peptide scaffolds by the breath figure method.

    PubMed

    Du, Mingchun; Zhu, Pengli; Yan, Xuehai; Su, Ying; Song, Weixing; Li, Junbai

    2011-04-01

    The self-assembly of molecules into desired architectures is currently a challenging subject for the development of supramolecular chemistry. Here we present a facile "breath figure" assembly process through the use of the self-assembled peptide building block diphenylalanine (L-Phe-L-Phe, FF). Macroporous honeycomb scaffolds were fabricated, and average pore size could be regulated, from (1.00±0.18) μm to (2.12±0.47) μm, through the use of different air speeds. It is indicated that the honeycomb formation is humidity-, solvent-, concentration-, and substrate-dependent. Moreover, water molecules introduced from "breath figure" intervene in the formation of hydrogen bonds during FF molecular self-assembly, which results in a hydrogen bond configuration transition from antiparallel β sheet to parallel β sheet. Meanwhile, as a result of the higher polarity of water molecules, the FF molecular array is transformed from laminar stacking into a hexagonal structure. These findings not only elucidate the FF molecule self-assembly process, but also strongly support the mechanism of breath figure array formation. Finally, human embryo skin fibroblast (ESF) culture experiments suggest that FF honeycomb scaffolds are an attractive biomaterial for growth of adherent cells with great potential applications in tissue engineering. PMID:21387428

  16. 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.

  17. Theory of Magnetic Phases in Hyperhoneycomb and Harmonic-honeycomb Iridates

    NASA Astrophysics Data System (ADS)

    Lee, Eric Kin Ho; Kim, Yong Baek

    2015-03-01

    Motivated by recent experiments, we consider a generic spin model in the jeff = 1 / 2 basis for the hyperhoneycomb and harmonic-honeycomb iridates. Based on microscopic considerations, the effect of an additional bond-dependent anisotropic spin exchange interaction (Γ) beyond the Heisenberg-Kitaev model is investigated. We obtain the magnetic phase diagrams of the hyperhoneycomb and harmonic-honeycomb (H-1) lattices via a combination of the Luttinger-Tisza approximation, single-Q variational ansatz, and classical Monte Carlo simulated annealing. The resulting phase diagrams on both systems show the existence of incommensurate, non-coplanar spiral magnetic orders as well as other commensurate magnetic orders. The spiral orders show counter-propagating spiral patterns, which may be favorably compared to recent experimental results on both iridates. The parameter regime of various magnetic orders and ordering wavevectors are quite similar in both systems. We discuss the implications of our work to recent experiments and also compare our results to those of the two dimensional honeycomb iridate systems. Computations were performed on the GPC supercomputer at the SciNet HPC Consortium. This research was supported by the NSERC, CIFAR, and Centre for Quantum Materials at the University of Toronto.

  18. 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 γ-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.

  19. An `H'-shape three-dimensional meta-material used in honeycomb structure absorbing material

    NASA Astrophysics Data System (ADS)

    Huang, Daqing; Kang, Feiyu; Zhou, Zhuohui; Cheng, Hongfei; Ding, Heyan

    2015-03-01

    An `H'-shape three-dimensional meta-material structure which loaded on the sidewall of honeycomb structure absorbing material was designed and fabricated in this project. The simulation results demonstrated a super-wide absorption band below -10 dB between 2.3 and 18 GHz, which expanded 7 GHz compared with the absorber without meta-material. The relative impedance curve was analyzed, which showed that the meta-material has little impact on the impedance-matching characteristics of the honeycomb structure absorbing material. We further studied the distribution of both electronic field energy and magnetic field energy. The former one indicated that the low-frequency absorption peaks could easily be moved by adjusting the parameters of the parallel-plate capacitors which generate electric resonance, and the latter one illustrated that the three-dimensional meta-material could generate magnetic resonance between units which would not exist in two-dimensional meta-material. Then we verified the simulation results through experiment which display a similar absorbing curve. The differences between simulation results and experiment results were caused by the addition substrate of the meta-material, which could not be eliminated in this experiment. However, it still implied that we can obtain a meta-material absorber that has a super-wide absorbing band if we can put the meta-material on the sidewall of the honeycomb without attachments.

  20. Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl3Nanosheets

    NASA Astrophysics Data System (ADS)

    Weber, Daniel; Schoop, Leslie M.; Duppel, Viola; Lippmann, Judith M.; Nuss, Jürgen; Lotsch, Bettina V.

    2016-06-01

    Spin $\\frac{1}{2}$ honeycomb materials have gained substantial interest due to their exotic magnetism and possible application in quantum computing. However, in all current materials out-of-plane interactions are interfering with the in-plane order, hence a true 2D magnetic honeycomb system is still of demand. Here, we report the exfoliation of the magnetic semiconductor $\\alpha$-RuCl$_3$ into the first halide monolayers and the magnetic characterization of the spin $\\frac{1}{2}$ honeycomb arrangement of turbostratically stacked RuCl$_3$ monolayers. The exfoliation is based on a reductive lithiation/hydration approach, which gives rise to a loss of cooperative magnetism due to the disruption of the spin $\\frac{1}{2}$ state by electron injection into the layers. After an oxidative treatment, cooperative magnetism similar to the bulk is restored. The oxidized pellets of restacked single layers feature a magnetic transition at T$_N$ = 7 K in the in-plane direction, while the magnetic properties in the out-of-plane direction vastly differ from bulk $\\alpha$-RuCl$_3$. The macroscopic pellets of RuCl$_3$ therefore behave like a stack of monolayers without any symmetry relation in the stacking direction. The deliberate introduction of turbostratic disorder to manipulate the spin structure of RuCl$_3$ is of interest for research in frustrated magnetism and complex magnetic order as predicted by the Kitaev-Heisenberg model.

  1. Topological honeycomb magnon Hall effect: A calculation of thermal Hall conductivity of magnetic spin excitations

    NASA Astrophysics Data System (ADS)

    Owerre, S. A.

    2016-07-01

    Quite recently, the magnon Hall effect of spin excitations has been observed experimentally on the kagome and pyrochlore lattices. The thermal Hall conductivity κxy changes sign as a function of magnetic field or temperature on the kagome lattice, and κxy changes sign upon reversing the sign of the magnetic field on the pyrochlore lattice. Motivated by these recent exciting experimental observations, we theoretically propose a simple realization of the magnon Hall effect in a two-band model on the honeycomb lattice. The magnon Hall effect of spin excitations arises in the usual way via the breaking of inversion symmetry of the lattice, however, by a next-nearest-neighbour Dzyaloshinsky-Moriya interaction. We find that κxy has a fixed sign for all parameter regimes considered. These results are in contrast to the Lieb, kagome, and pyrochlore lattices. We further show that the low-temperature dependence on the magnon Hall conductivity follows a T2 law, as opposed to the kagome and pyrochlore lattices. These results suggest an experimental procedure to measure thermal Hall conductivity within a class of 2D honeycomb quantum magnets and ultracold atoms trapped in a honeycomb optical lattice.

  2. 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.

  3. Magnetic Properties of Restacked 2D Spin 1/2 honeycomb RuCl3 Nanosheets.

    PubMed

    Weber, Daniel; Schoop, Leslie M; Duppel, Viola; Lippmann, Judith M; Nuss, Jürgen; Lotsch, Bettina V

    2016-06-01

    Spin 1/2 honeycomb materials have gained substantial interest due to their exotic magnetism and possible application in quantum computing. However, in all current materials out-of-plane interactions are interfering with the in-plane order, hence a true 2D magnetic honeycomb system is still in demand. Here, we report the exfoliation of the magnetic semiconductor α-RuCl3 into the first halide monolayers and the magnetic characterization of the spin 1/2 honeycomb arrangement of turbostratically stacked RuCl3 monolayers. The exfoliation is based on a reductive lithiation/hydration approach, which gives rise to a loss of cooperative magnetism due to the disruption of the spin 1/2 state by electron injection into the layers. The restacked, macroscopic pellets of RuCl3 layers lack symmetry along the stacking direction. After an oxidative treatment, cooperative magnetism similar to the bulk is restored. The oxidized pellets of restacked single layers feature a magnetic transition at TN = 7 K if the field is aligned parallel to the ab-plane, while the magnetic properties differ from bulk α-RuCl3 if the field is aligned perpendicular to the ab-plane. The deliberate introduction of turbostratic disorder to manipulate the magnetic properties of RuCl3 is of interest for research in frustrated magnetism and complex magnetic order as predicted by the Kitaev-Heisenberg model. PMID:27176463

  4. 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

  5. Two-Dimensional Iron Tungstate: A Ternary Oxide Layer With Honeycomb Geometry

    PubMed Central

    2016-01-01

    The exceptional physical properties of graphene have sparked tremendous interests toward two-dimensional (2D) materials with honeycomb structure. We report here the successful fabrication of 2D iron tungstate (FeWOx) layers with honeycomb geometry on a Pt(111) surface, using the solid-state reaction of (WO3)3 clusters with a FeO(111) monolayer on Pt(111). The formation process and the atomic structure of two commensurate FeWOx phases, with (2 × 2) and (6 × 6) periodicities, have been characterized experimentally by combination of scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption (TPD) and understood theoretically by density functional theory (DFT) modeling. The thermodynamically most stable (2 × 2) phase has a formal FeWO3 stoichiometry and corresponds to a buckled Fe2+/W4+ layer arranged in a honeycomb lattice, terminated by oxygen atoms in Fe–W bridging positions. This 2D FeWO3 layer has a novel structure and stoichiometry and has no analogues to known bulk iron tungstate phases. It is theoretically predicted to exhibit a ferromagnetic electronic ground state with a Curie temperature of 95 K, as opposed to the antiferromagnetic behavior of bulk FeWO4 materials. PMID:27110319

  6. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  7. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  8. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  9. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  10. 21 CFR 73.1645 - Aluminum powder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Aluminum powder. 73.1645 Section 73.1645 Food and... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1645 Aluminum powder. (a) Identity. (1) The color additive aluminum powder shall be composed of finely divided particles of aluminum prepared from virgin aluminum....

  11. Quasicrystalline particulate reinforced aluminum composite

    SciTech Connect

    Anderson, I.E.; Biner, S.B.; Sordelet, D.J.; Unal, O.

    1997-07-01

    Particulate reinforced aluminum and aluminum alloy composites are rapidly emerging as new commercial materials for aerospace, automotive, electronic packaging and other high performance applications. However, their low processing ductility and difficulty in recyclability have been the key concern. In this study, two composite systems having the same aluminum alloy matrix, one reinforced with quasicrystals and the other reinforced with the conventional SiC reinforcements were produced with identical processing routes. Their processing characteristics and tensile mechanical properties were compared.

  12. Cathodic phenomena in aluminum electrowinning

    NASA Astrophysics Data System (ADS)

    Bouteillon, J.; Poignet, J. C.; Rameau, J. J.

    1993-02-01

    Although aluminum is one of the world's highest production-volume primary metals, it is particularly costly to produce for a variety of factors, not the least of which are the expenses associated with electrolytic reduction. Based on the scale of global aluminum processing, even minor improvements in the electrowinning technology can result in significant savings of resources. Thus, from this perspective, the following reviews recent studies of cathodic phenomena in aluminum electrowinning.

  13. A comparative study of the impact properties of sandwich materials with different cores

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, K. R.; Shankar, K.; Viot, P.; Guerard, S.

    2012-08-01

    Sandwich panels are made of two high strength skins bonded to either side of a light weight core and are used in applications where high stiffness combined with low structural weight is required. The purpose of this paper is to compare the mechanical response of several sandwich panels whose core materials are different. Sandwich panels with glass fibre-reinforced polymer face sheets were used, combined with five different cores; polystyrene foam, polypropylene honeycomb, two different density Balsa wood and Cork. All specimens were subjected to low velocity impact and their structural response (Force-displacement curves) were compared to quasistatic response of the panel tested using an hemispherical indenter.

  14. 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.

  15. 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.

  16. Mechanics of pressure-adaptive honeycomb and its application to wing morphing

    NASA Astrophysics Data System (ADS)

    Vos, Roelof; Barrett, Ron

    2011-09-01

    Current, highly active classes of adaptive materials have been considered for use in many different aerospace applications. From adaptive flight control surfaces to wing surfaces, shape-memory alloy (SMA), piezoelectric and electrorheological fluids are making their way into wings, stabilizers and rotor blades. Despite the benefits which can be seen in many classes of aircraft, some profound challenges are ever present, including low power and energy density, high power consumption, high development and installation costs and outright programmatic blockages due to a lack of a materials certification database on FAR 23/25 and 27/29 certified aircraft. Three years ago, a class of adaptive structure was developed to skirt these daunting challenges. This pressure-adaptive honeycomb (PAH) is capable of extremely high performance and is FAA/EASA certifiable because it employs well characterized materials arranged in ways that lend a high level of adaptivity to the structure. This study is centered on laying out the mechanics, analytical models and experimental test data describing this new form of adaptive material. A directionally biased PAH system using an external (spring) force acting on the PAH bending structure was examined. The paper discusses the mechanics of pressure adaptive honeycomb and describes a simple reduced order model that can be used to simplify the geometric model in a finite element environment. The model assumes that a variable stiffness honeycomb results in an overall deformation of the honeycomb. Strains in excess of 50% can be generated through this mechanism without encountering local material (yield) limits. It was also shown that the energy density of pressure-adaptive honeycomb is akin to that of shape-memory alloy, while exhibiting strains that are an order of magnitude greater with an energy efficiency close to 100%. Excellent correlation between theory and experiment is demonstrated in a number of tests. A proof-of-concept wing section

  17. 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.

  18. Production of aluminum metal by electrolysis of aluminum sulfide

    DOEpatents

    Minh, Nguyen Q.; Loutfy, Raouf O.; Yao, Neng-Ping

    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.

  19. Critical properties of aluminum.

    PubMed

    Bhatt, Divesh; Jasper, Ahren W; Schultz, Nathan E; Siepmann, J Ilja; Truhlar, Donald G

    2006-04-01

    Gibbs ensemble Monte Carlo calculations are performed using a validated embedded-atom potential to obtain the vapor-liquid coexistence curve for elemental aluminum in good agreement with available experimental data up to the boiling point. These calculations are then extended to make a reliable prediction of the critical temperature, pressure, and density of Al, which have previously been known only with very large uncertainties. This demonstrates the ability of modern simulations to predict fundamental physical properties that are extremely difficult to measure directly. PMID:16568986

  20. Metal Foam Shields

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.

    2006-01-01

    This paper compares the ballistic performance of metallic foam sandwich structures with honeycomb structures. Honeycomb sandwich structures, consisting of metallic or composite facesheets and honeycomb cores, are often used in spacecraft construction due to their light-weight and structural stiffness. Honeycomb panels, however, are considered rather poor candidates for protection from micrometeoroid orbital debris (MMOD) particles because the honeycomb channels the debris cloud from MMOD impacts on outer facesheet causing a concentrated load on the second facesheet. Sandwich structures with light-weight, open-cell metallic cores and metal or composite facesheets provide improved MMOD protection because channeling does not occur and because the core is more effective at disrupting hypervelocity impacts then honeycomb. This paper describes hypervelocity impact tests on metallic foam sandwich structures (aluminum and titanium) with metallic facesheets, compare them to equivalent mass and thickness honeycomb panels, based on the results of hypervelocity impact tests.

  1. Design Criteria for X-CRV Honeycomb Panels: A Preliminary Study

    NASA Technical Reports Server (NTRS)

    Caccese, Vincent; Verinder, Irene

    1997-01-01

    The objective of this project is to perform the first step in developing structural design criteria for composite sandwich panels that are to be used in the aeroshell of the crew return vehicle (X-CRV). The preliminary concept includes a simplified method for assessing the allowable strength in the laminate material. Ultimately, it is intended that the design criteria be extended to address the global response of the vehicle. This task will require execution of a test program as outlined in the recommendation section of this report. The aeroshell of the X-CRV is comprised of composite sandwich panels consisting of fiberite face sheets and a phenolic honeycomb core. The function of the crew return vehicle is to enable the safe return of injured or ill crewpersons from space station, the evacuation of crew in case of emergency or the return of crew if an orbiter is not available. A significant objective of the X-CRV project is to demonstrate that this vehicle can be designed, built and operated at lower cost and at a significantly faster development time. Development time can be reduced by driving out issues in both structural design and manufacturing concurrently. This means that structural design and analysis progresses in conjunction with manufacturing and testing. Preliminary tests results on laminate coupons are presented in the report. Based on these results a method for detection material failure in the material is presented. In the long term, extrapolation of coupon data to large scale structures may be inadequate. Test coupons used to develop failure criteria at the material scale are typically small when compared to the overall structure. Their inherent small size indicates that the material failure criteria can be used to predict localized failure of the structure, however, it can not be used to predict failure for all failure modes. Some failure modes occur only when the structure or one of its sub-components are studied as a whole. Conversely, localized

  2. 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.

  3. 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

  4. 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)

  5. 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

  6. 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)

  7. Boron carbide-aluminum cermets

    SciTech Connect

    Halverson, D.C.

    1986-09-03

    We have developed boron carbide-aluminum cermets by means of thermodynamic, kinetic, and processing studies. Our research indicates that boron carbide-aluminum cermets offer ''tailorable'' microstructures with designable properties through process control. This new class of cermets has the potential to become a very important material with wide industrial applications.

  8. 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

  9. 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...

  10. 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.

  11. The thermomechanical stability of micro-solid oxide fuel cells fabricated on anodized aluminum oxide membranes

    NASA Astrophysics Data System (ADS)

    Kwon, Chang-Woo; Lee, Jae-Il; Kim, Ki-Bum; Lee, Hae-Weon; Lee, Jong-Ho; Son, Ji-Won

    2012-07-01

    The thermomechanical stability of micro-solid oxide fuel cells (micro-SOFCs) fabricated on an anodized aluminum oxide (AAO) membrane template is investigated. The full structure consists of the following layers: AAO membrane (600 nm)/Pt anode/YSZ electrolyte (900 nm)/porous Pt cathode. The utilization of a 600-nm-thick AAO membrane significantly improves the thermomechanical stability due to its well-known honeycomb-shaped nanopore structure. Moreover, the Pt anode layer deposited in between the AAO membrane and the YSZ electrolyte preserves its integrity in terms of maintaining the triple-phase boundary (TPB) and electrical conductivity during high-temperature operation. Both of these results guarantee thermomechanical stability of the micro-SOFC and extend the cell lifetime, which is one of the most critical issues in the fabrication of freestanding membrane-type micro-SOFCs.

  12. Channeling of aluminum in silicon

    SciTech Connect

    Wilson, R.G.; Hopkins, C.G.

    1985-05-15

    A systematic study of channeling of aluminum in the silicon crystal is reported. Depth distributions measured by secondary ion mass spectrometry are reported for 40-, 75-, and 150-keV aluminum channeled in the <100> and <110> directions of silicon. The profile dependence on alignment angle is shown for 150-keV aluminum in the <110> of silicon. Aluminum has low electronic stopping in silicon and corresponding deep channeled profiles are observed for aligned implants and deep channeling tails are observed on random implants. The maximum channeling range for 150-keV Al in <100> silicon is about 2.8 ..mu..m and is about 6.4 ..mu..m in <110> silicon. Some ions will reach the maximum channeling range even for 2/sup 0/ misalignment. Many of the deep channeling tails and ''supertails'' reported in earlier literature can be explained by the normal channeling of aluminum in silicon.

  13. Incommensurate counterrotating magnetic order stabilized by Kitaev interactions in the layered honeycomb α -Li2IrO3

    NASA Astrophysics Data System (ADS)

    Williams, S. Â. C.; Johnson, R. Â. D.; Freund, F.; Choi, Sungkyun; Jesche, A.; Kimchi, I.; Manni, S.; Bombardi, A.; Manuel, P.; Gegenwart, P.; Coldea, R.

    2016-05-01

    The layered honeycomb magnet α -Li2IrO3 has been theoretically proposed as a candidate to display unconventional magnetic behaviour associated with Kitaev interactions between spin-orbit entangled jeff=1 /2 magnetic moments on a honeycomb lattice. Here we report single crystal magnetic resonant x-ray diffraction combined with powder magnetic neutron diffraction to reveal an incommensurate magnetic order in the honeycomb layers with Ir magnetic moments counterrotating on nearest-neighbor sites. This unexpected type of magnetic structure for a honeycomb magnet cannot be explained by a spin Hamiltonian with dominant isotropic (Heisenberg) couplings. The magnetic structure shares many key features with the magnetic order in the structural polytypes β - and γ -Li2IrO3 , understood theoretically to be stabilized by dominant Kitaev interactions between Ir moments located on the vertices of three-dimensional hyperhoneycomb and stripyhoneycomb lattices, respectively. Based on this analogy and a theoretical soft-spin analysis of magnetic ground states for candidate spin Hamiltonians, we propose that Kitaev interactions also dominate in α -Li2IrO3 , indicative of universal Kitaev physics across all three members of the harmonic honeycomb family of Li2IrO3 polytypes.

  14. Synthesis of honeycomb MnO2 nanospheres/carbon nanoparticles/graphene composites as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Xiong, Yachao; Zhou, Min; Chen, Hao; Feng, Lei; Wang, Zhao; Yan, Xinzhu; Guan, Shiyou

    2015-12-01

    Improving the electrochemical performance of manganese dioxide (MnO2) electrodes is of great significance for supercapacitors. In this study, a novel honeycomb MnO2 nanospheres/carbon nanoparticles/graphene composites has been fabricated through freeze-drying method. The honeycomb MnO2 nanospheres are well inserted and dispersed on the graphene. Carbon nanoparticles in the composites act as spacers to effectively prevent graphene from restacking and agglomeration, construct efficient 3D conducting architecture with graphene for honeycomb MnO2 nanospheres, and alleviate the aggregation of honeycomb MnO2 nanospheres by separating them from each other. As a result, such honeycomb MnO2 nanospheres/carbon nanoparticles/graphene composites display much improved electrochemical capacitive performance of 255 F g-1 at a current density of 0.5 A g-1, outstanding rate capability (150 F g-1 remained at a current density of 20 A g-1) and good cycling stability (83% of the initial capacitance retained after 1000 charge/discharge cycles). The strategy for the synthesis of these composites is very effective.

  15. 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.

  16. Aluminum Zintl anion moieties within sodium aluminum clusters

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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, NamAln-, 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.

  17. Aluminum Zintl anion moieties within sodium aluminum clusters.

    PubMed

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

    2014-02-01

    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(m)Al(n)(-), 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. PMID:24511934

  18. First principles pseudopotential calculations on aluminum and aluminum alloys

    SciTech Connect

    Davenport, J.W.; Chetty, N.; Marr, R.B.; Narasimhan, S.; Pasciak, J.E.; Peierls, R.F.; Weinert, M.

    1993-12-31

    Recent advances in computational techniques have led to the possibility of performing first principles calculations of the energetics of alloy formation on systems involving several hundred atoms. This includes impurity concentrations in the 1% range as well as realistic models of disordered materials (including liquids), vacancies, and grain boundaries. The new techniques involve the use of soft, fully nonlocal pseudopotentials, iterative diagonalization, and parallel computing algorithms. This approach has been pioneered by Car and Parrinello. Here the authors give a review of recent results using parallel and serial algorithms on metallic systems including liquid aluminum and liquid sodium, and also new results on vacancies in aluminum and on aluminum-magnesium alloys.

  19. 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.

  20. 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