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Sample records for sandwich panel structures

  1. High temperature structural sandwich panels

    Science.gov (United States)

    Papakonstantinou, Christos G.

    High strength composites are being used for making lightweight structural panels that are being employed in aerospace, naval and automotive structures. Recently, there is renewed interest in use of these panels. The major problem of most commercial available sandwich panels is the fire resistance. A recently developed inorganic matrix is investigated for use in cases where fire and high temperature resistance are necessary. The focus of this dissertation is the development of a fireproof composite structural system. Sandwich panels made with polysialate matrices have an excellent potential for use in applications where exposure to high temperatures or fire is a concern. Commercial available sandwich panels will soften and lose nearly all of their compressive strength temperatures lower than 400°C. This dissertation consists of the state of the art, the experimental investigation and the analytical modeling. The state of the art covers the performance of existing high temperature composites, sandwich panels and reinforced concrete beams strengthened with Fiber Reinforced Polymers (FRP). The experimental part consists of four major components: (i) Development of a fireproof syntactic foam with maximum specific strength, (ii) Development of a lightweight syntactic foam based on polystyrene spheres, (iii) Development of the composite system for the skins. The variables are the skin thickness, modulus of elasticity of skin and high temperature resistance, and (iv) Experimental evaluation of the flexural behavior of sandwich panels. Analytical modeling consists of a model for the flexural behavior of lightweight sandwich panels, and a model for deflection calculations of reinforced concrete beams strengthened with FRP subjected to fatigue loading. The experimental and analytical results show that sandwich panels made with polysialate matrices and ceramic spheres do not lose their load bearing capability during severe fire exposure, where temperatures reach several

  2. A multifunctional heat pipe sandwich panel structure

    Energy Technology Data Exchange (ETDEWEB)

    Queheillalt, Douglas T.; Wadley, Haydn N.G. [University of Virginia, Department of Materials Science and Engineering, 140 Chemistry Way, P.O. Box 400745, Charlottesville, VA 22904 (United States); Carbajal, Gerardo [University of Turabo, School of Engineering, P.O. Box 3030, Gurabo 00778 (Puerto Rico); Peterson, G.P. [University of Colorado at Boulder, 914 Broadway, Boulder, CO 80309 (United States)

    2008-01-15

    A multifunctional sandwich panel combining efficient structural load support and thermal management characteristics has been designed and experimentally assessed. The concept is based upon a truncated, square honeycomb sandwich structure. In closed cell honeycomb structures, the transport of heat from one face to the other occurs by a combination of conduction through the webs and convection/radiation within the cells. Here, much more effective heat transport is achieved by multifunctionally utilizing the core as a heat pipe sandwich panel. Its interior consists of a 6061 aluminum truncated-square honeycomb core covered with a stochastic open-cell nickel foam wick. An electroless nickel plating barrier layer inhibited the chemical reaction between the deionized water working fluid and the aluminum structure, retarding the generation of non-condensable hydrogen gas. A thermodynamic model was used to guide the design of the heat pipe sandwich panel. We describe the results of a series of experiments that validate the operational principle of the multifunctional heat pipe sandwich panel and characterize its transient response to an intense localized heat source. The systems measured thermal response to a localized heat source agrees well with that predicted by a finite difference method model used to predict the thermal response. (author)

  3. Structural detailing of openings in sandwich panels

    NARCIS (Netherlands)

    Tomà, T.; Courage, W.

    1996-01-01

    European Recommendations exist which provide calculation rules to determine the strength and stiffness of sandwich panels composed of two metal faces with a foam in between. In case of openings in such panels (e.g. for windows) an influence will appear with regard to the stiffness and loadbearing

  4. Sandwich Panel as a Structural Element of Overlap

    Directory of Open Access Journals (Sweden)

    Novikov Maxim

    2016-01-01

    Full Text Available This paper considers the issue of sandwich panels using as load-bearing structural elements. The comparison of deflections and critical failure loads were obtained by the results of the full-scale roof sandwich panels tests conducted by the company “Joris Ide” and the theoretical design, according to the calculation method described in Euronorms. Based on these results it was concluded that sandwich panels can be treated as a load-bearing structure only with more taught manufacturing requirements. Thus, the reduced spread of critical loads can be achieved.

  5. Transient Thermal Testing and Analysis of a Thermally Insulating Structural Sandwich Panel

    Science.gov (United States)

    Blosser, Max L.; Daryabeigi, Kamran; Bird, Richard K.; Knutson, Jeffrey R.

    2015-01-01

    A core configuration was devised for a thermally insulating structural sandwich panel. Two titanium prototype panels were constructed to illustrate the proposed sandwich panel geometry. The core of one of the titanium panels was filled with Saffil(trademark) alumina fibrous insulation and the panel was tested in a series of transient thermal tests. Finite element analysis was used to predict the thermal response of the panel using one- and two-dimensional models. Excellent agreement was obtained between predicted and measured temperature histories.

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

    Science.gov (United States)

    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

  7. A ballistic limit equation for hypervelocity impacts on composite honeycomb sandwich panel satellite structures

    Science.gov (United States)

    Ryan, S.; Schaefer, F.; Destefanis, R.; Lambert, M.

    During a recent experimental test campaign performed in the framework of ESA Contract 16721, the ballistic performance of multiple satellite-representative Carbon Fibre Reinforced Plastic (CFRP)/Aluminium honeycomb sandwich panel structural configurations (GOCE, Radarsat-2, Herschel/Planck, BeppoSax) was investigated using the two-stage light-gas guns at EMI. The experimental results were used to develop and validate a new empirical Ballistic Limit Equation (BLE), which was derived from an existing Whipple-shield BLE. This new BLE provided a good level of accuracy in predicting the ballistic performance of stand-alone sandwich panel structures. Additionally, the equation is capable of predicting the ballistic limit of a thin Al plate located at a standoff behind the sandwich panel structure. This thin plate is the representative of internal satellite systems, e.g. an Al electronic box cover, a wall of a metallic vessel, etc. Good agreement was achieved with both the experimental test campaign results and additional test data from the literature for the vast majority of set-ups investigated. For some experiments, the ballistic limit was conservatively predicted, a result attributed to shortcomings in correctly accounting for the presence of high surface density multi-layer insulation on the outer facesheet. Four existing BLEs commonly applied for application with stand-alone sandwich panels were reviewed using the new impact test data. It was found that a number of these common approaches provided non-conservative predictions for sandwich panels with CFRP facesheets.

  8. Structural Response of Polyethylene Foam-Based Sandwich Panels Subjected to Edgewise Compression

    Directory of Open Access Journals (Sweden)

    Luciano Lamberti

    2013-10-01

    Full Text Available This study analyzes the mechanical behavior of low density polyethylene foam core sandwich panels subjected to edgewise compression. In order to monitor panel response to buckling, strains generated in the facesheets and overall out-of-plane deformations are measured with strain gages and projection moiré, respectively. A finite element (FE model simulating the experimental test is developed. Numerical results are compared with moiré measurements. After having been validated against experimental evidence, the FE model is parameterized, and a trade study is carried out to investigate to what extent the structural response of the panel depends on the sandwich wall construction and facesheet/core interface defects. The projection moiré set-up utilized in this research is able to capture the sudden and very localized buckling phenomena occurring under edgewise compression of foam-based sandwich panels. Results of parametric FE analyses indicate that, if the total thickness of the sandwich wall is fixed, including thicker facesheets in the laminate yields a larger deflection of the panel that becomes more sensitive to buckling. Furthermore, the mechanical response of the foam sandwich panel is found to be rather insensitive to the level of waviness of core-facesheet interfaces.

  9. Structural performance of new thin-walled concrete sandwich panel system reinforced with bfrp shear connectors

    DEFF Research Database (Denmark)

    Hodicky, Kamil; Hulin, Thomas; Schmidt, Jacob Wittrup

    2013-01-01

    This paper presents a new thin-walled concrete sandwich panel system reinforced with basalt fiber-reinforced plastic (BFRP) with optimum structural performances and a high thermal resistance developed by Connovate and Technical University of Denmark. The shear connecting system made of a BFRP grid...

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

    Science.gov (United States)

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

    2010-01-01

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

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

    Science.gov (United States)

    Ko, William L.; Jackson, Raymond H.

    1991-01-01

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

  12. EVALUATION OF THE STRUCTURAL BEHAVIOR OF ALUMINUM HONEYCOMB SANDWICH PANELS FOR MICROSATELLITES

    OpenAIRE

    Silva, Hiterson de Oliveira; Andrianov, Artem; Barcelos Júnior, Manuel Nascimento Dias

    2017-01-01

      Abstract. This work has as target the analysis of honeycomb structures by applying analytical models and numerical simulation that employ different finite element approaches: solid model for panel with equivalent honeycomb core properties, solid model of the honeycomb core and faces, and surface model of the honeycomb core and faces. There is also the standard test method for determination of the bending and shear properties of honeycomb sandwich samples whose results are employed for valid...

  13. Behaviour of Metal Foam Sandwich Panels

    DEFF Research Database (Denmark)

    Alkhudery, Hayder; Virdi, Kuldeep

    2011-01-01

    Sandwich panels as used in structures comprise of a foam core enclosed by thin high strength steel faces. This paper discusses currently design formulae of local buckling behaviour of such panels using the finite element method. Multiple wave finite element models were adopted to investigate...

  14. Thermo-structural optimization of all-metallic prismatic sandwich panels

    Science.gov (United States)

    Valdevit, Lorenzo

    All-metallic sandwich panels with prismatic cores offer tremendous potential for thermostructural applications, due to their exceptional bending response together with the possibility of driving a fluid through their open cores, thus enabling active cooling. This thesis offers a complete thermo-mechanical characterization of prismatic panels with both corrugated and diamond cores, with main emphasis on geometric optimization. For the mechanical study, the panel geometry is analytically optimized for minimum weight under any combination of bending and transverse shear force. For longitudinal loadings (i.e. bending axis parallel to the core corrugation direction), corrugated panels show excellent performance, equivalent to the best concepts available; for transverse loadings (i.e. bending axis perpendicular to the corrugation direction), this goal is achieved with diamond core designs. Failure maps are constructed based on the analytical model to provide easy visualization of the failure modes and allow immediate identification of optimal designs. Such maps are used to design a selected number of experiments, with the three-fold goal of (i) validating the analytical model, (ii) exploring the behavior subsequent to failure initiation (thus assessing the robustness of the chosen designs), and (iii) check the reliability of numerical simulations in capturing limit loads and deformation modes. Good agreement is achieved among analytical, computational and experimental results. In order to assess the active cooling performance of prismatic panels, a scenario is envisioned where a uniform heat flux is impinging on one face, with the rest of the panel being thermally insulated; under these conditions, all the heat flux is transferred to a cooling fluid flowing through the core channels. At any given level of the pressure drop, the panel geometry is optimized for maximum transferred heat flux subject to a temperature constraint on the structure. Although very large optimal

  15. X-joints in composite sandwich panels

    NARCIS (Netherlands)

    Vredeveldt, A.W.; Janssen, G.Th.M.

    1998-01-01

    The small structural weight of fast large ships such as fast mono hulls or catamaran type of ships is of extreme importance to their success. One possible light weight structural solution is the sandwich panel with fibre reinforced laminates and a balsa, honeycomb or foam core. A severe obstacle for

  16. Buckling optimisation of sandwich cylindrical panels

    Science.gov (United States)

    Abouhamzeh, M.; Sadighi, M.

    2016-06-01

    In this paper, the buckling load optimisation is performed on sandwich cylindrical panels. A finite element program is developed in MATLAB to solve the governing differential equations of the global buckling of the structure. In order to find the optimal solution, the genetic algorithm Toolbox in MATLAB is implemented. Verifications are made for both the buckling finite element code and also the results from the genetic algorithm by comparisons to the results available in literature. Sandwich cylindrical panels are optimised for the buckling strength with isotropic or orthotropic cores with different boundary conditions. Results are presented in terms of stacking sequence of fibers in the face sheets and core to face sheet thickness ratio.

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

    Science.gov (United States)

    Ko, William L.; Jackson, Raymond H.

    1993-01-01

    Combined inplane compressive and shear buckling analysis was conducted on flat rectangular sandwich panels using the Raleigh-Ritz minimum energy method with a consideration of transverse shear effect of the sandwich core. The sandwich panels were fabricated with titanium honeycomb core and laminated metal matrix composite face sheets. The results show that slightly slender (along unidirectional compressive loading axis) rectangular sandwich panels have the most desirable stiffness-to-weight ratios for aerospace structural applications; the degradation of buckling strength of sandwich panels with rising temperature is faster in shear than in compression; and the fiber orientation of the face sheets for optimum combined-load buckling strength of sandwich panels is a strong function of both loading condition and panel aspect ratio. Under the same specific weight and panel aspect ratio, a sandwich panel with metal matrix composite face sheets has much higher buckling strength than one having monolithic face sheets.

  18. Damage assessment of compression loaded debond damaged sandwich panels

    DEFF Research Database (Denmark)

    Moslemian, Ramin; Berggreen, Christian; Quispitupa, Amilcar

    2010-01-01

    with an implanted circular face/core debond. Compression tests were conducted on intact sandwich panels and panels with an implanted circular face/core debond with three different types of foam core materials (PVC H130, PVC H250 and PMI 51-IG). The strains and out-of-plane displacements of the debonded region were...... be minimized. Some of these applications involve the use of highly optimized sandwich solutions. Studies are under way to establish how the structural performance is influenced by the presence of production defects or in-service damage. This paper deals with the failure of compression loaded sandwich panels...... monitored using digital image correlation (DIC) measurements. Mixed mode bending (MMB) fracture characterization tests were conducted to determine the fracture toughness of the face/core interface in the panels. Finite element analysis and linear elastic fracture mechanics were employed to determine...

  19. ANALISIS KERAGAAN PANEL SANDWICH UNTUK RUMAH PRA-PABRIKASI

    Directory of Open Access Journals (Sweden)

    Naresworo Nugroho

    2010-12-01

    Full Text Available In the last five years, several earthquakes struck several places in Indonesia and thousands of people died caused of their masonry house. Therefore, the idea of bamboo utilization in the form of structural sandwich panel components for anti-seismic pre-fabrication house is one of appropriate way out. This research describes the performance and behavior of engineered structure wooden-bamboo sandwich panel in full sized test. The wall frame being use were meranti wood, this frame attached by plywood as face and back, then 5 cm bamboo cutting as core; the fastener used in this study were isocyanate resin and nails. This study carried out by experimental data of full scale structural tests on shear wall (ISO 22452. These result showed that the seismic reliability of the wall frame system made of bamboo sandwich panel was appropriate and will be useful for pre-fabrication houses as anti-seismic and environment friendly residential building

  20. Utilization of Bamboo as Lightweight Sandwich Panels

    Directory of Open Access Journals (Sweden)

    Suthon SRIVARO

    2016-05-01

    Full Text Available Lightweight sandwich panels consisting of bamboo faces and oil palm trunk core were manufactured using melamine urea formaldehyde with the resin content of 250 g/m2 (solid basis. The parameters examined were node and density of bamboo faces. Physical (board density, thickness swelling and water absorption and mechanical (modulus of elasticity and modulus of rupture properties of the sandwich board obtained were investigated and compared with other bamboo products and commercial wood based products. Result showed that this panel had better dimensional stability than those of other bamboo products but lower bending strength. Node of bamboo had no significant effect on any board properties examined. Most of board properties were influenced by bamboo face density. Comparing the properties to commercial wood based products, this panel could be used as wall/floor applications.

  1. Investigation on Wall Panel Sandwiched With Lightweight Concrete

    Science.gov (United States)

    Lakshmikandhan, K. N.; Harshavardhan, B. S.; Prabakar, J.; Saibabu, S.

    2017-08-01

    The rapid population growth and urbanization have made a massive demand for the shelter and construction materials. Masonry walls are the major component in the housing sector and it has brittle characteristics and exhibit poor performance against the uncertain loads. Further, the structure requires heavier sections for carrying the dead weight of masonry walls. The present investigations are carried out to develop a simple, lightweight and cost effective technology for replacing the existing wall systems. The lightweight concrete is developed for the construction of sandwich wall panel. The EPS (Expanded Polystyrene) beads of 3 mm diameter size are mixed with concrete and developed a lightweight concrete with a density 9 kN/m3. The lightweight sandwich panel is cast with a lightweight concrete inner core and ferrocement outer skins. This lightweight wall panel is tested for in-plane compression loading. A nonlinear finite element analysis with damaged plasticity model is carried out with both material and geometrical nonlinearities. The experimental and analytical results were compared. The finite element study predicted the ultimate load carrying capacity of the sandwich panel with reasonable accuracy. The present study showed that the lightweight concrete is well suitable for the lightweight sandwich wall panels.

  2. Bending and Deformation of Sandwich Panels Due to Localized Pressure

    Directory of Open Access Journals (Sweden)

    Bambang K. Hadi

    2005-05-01

    Full Text Available Bending and deformation of sandwich panels due to localized pressure were analyzed using both Rayleigh-Ritz and finite element methods. The faces were made of laminated composite plates, while the core was a honeycomb material. Carbon fiber and glass fiber reinforced plastics were used for composite plate faces. In the case of Rayleigh-Ritz method, first the total energy of the system was calculated and then taking the variations of the total energy, the sandwich panel deflections could be computed. The deflections were assumed by means of Fourier series. A finite element code NASTRAN was exploited extensively in the finite element method. 3-dimensional 8-node brick elements were used to model sandwich panels, for both the faces sheets and the core. The results were then compared to each other and in general they are in good agreements. Dimple phenomena were found in these cases. It shows that localized pressure on sandwich structures will produce dimple on the pressurize region with little effects on the rest of the structures.

  3. Residual Strength Prediction of Debond Damaged Sandwich Panels

    DEFF Research Database (Denmark)

    Berggreen, Carl Christian

    propagation and initiation, as these mechanisms are governing for the overall failure load of the structure. Thus, this presentation will describe the development, validation and application of a FEM based numerical model for prediction of residual strength of damaged sandwich panels. The core......This presentation concerns theoretical and experimental prediction of crack propagation and residual strength of debond damaged sandwich panels. It is evident that in order to achieve highly optimised structures which are able to operate in a stochastic loading environment, damage tolerance...... evaluation based on residual strength prediction is needed. Is a given damage critical for the structural integrity needing immanent repair, or is the damage negligible, where repair can be postponed to the next inspection? These questions are generally interesting for all types of structures...

  4. Laser welded steel sandwich panel bridge deck development : finite element analysis and stake weld strength tests.

    Science.gov (United States)

    2009-09-01

    This report summarizes the analysis of laser welded steel sandwich panels for use in bridge structures and : static testing of laser stake welded lap shear coupons. Steel sandwich panels consist of two face sheets : connected by a relatively low-dens...

  5. Experimental validation of the Higher-Order Theory approach for sandwich panels with flexible core materials

    NARCIS (Netherlands)

    Straalen, IJ.J. van

    2000-01-01

    During tthe 1990's the higher-order theory was developed by Frostig to enable detailed stress analyses of sandwich panel structures. To investigate the potentials of this approach experiments are performed on sandwich panels made of thin steel faces and mineral wool or polystyrene core material. A

  6. Deformation and fracture of impulsively loaded sandwich panels

    Science.gov (United States)

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

    2013-02-01

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

  7. Flexural Strength of Functionally Graded Nanotube Reinforced Sandwich Spherical Panel

    Science.gov (United States)

    Mahapatra, Trupti R.; Mehar, Kulmani; Panda, Subrata K.; Dewangan, S.; Dash, Sushmita

    2017-02-01

    The flexural behaviour of the functionally graded sandwich spherical panel under uniform thermal environment has been investigated in the present work. The face sheets of the sandwich structure are made by the functionally graded carbon nanotube reinforced material and the core face is made by the isotropic and homogeneous material. The material properties of both the fiber and matrix are assumed to be temperature dependent. The sandwich panel model is developed in the framework of the first order shear deformation theory and the governing equation of motion is derived using the variational principle. For the discretization purpose a suitable shell element has been employed from the ANSYS library and the responses are computed using a parametric design language (APDL) coding. The performance and accuracy of the developed model has been established through the convergence and validation by comparing the obtained results with previously published results. Finally, the influence of different geometrical parameters and material properties on the flexural behaviour of the sandwich spherical panel in thermal environment has been investigated through various numerical illustrations and discussed in details.

  8. New "sandwich" structures conformed from three dimensional

    Directory of Open Access Journals (Sweden)

    Alba, Juan J.

    1996-03-01

    Full Text Available Poor interlaminar properties as well as poor-skin-to-core adhesion properties are very often the common existing problems we find when designing with "sandwich" structures. A new type of 3D-fabric "sandwich" structure is being developed in order to avoid these problems. Although the manufacturing process is very simple, a very complex "sandwich" structure is obtained as a result of the complexity of the 3D-fabric used. This 3D-fabric is a 3D woven glass fabric produced on velvet weaving machines with glass yarns. It is an integrally woven "sandwich" laminate for all kinds of composite products. The strength of the vertical fibers makes, that also after impregnation with a resin matrix, the "sandwich" structure is maintained. The result is a laminate with high strength and stiffness and low weight. On each side of this "sandwich" laminate additional reinforcement materials can be laminated and a synthetic foam can be injected in the hollow structure. This will allow to establish the mechanical properties of a finished product.

    Las pobres propiedades, tanto interlaminares como de adhesión entre piel y núcleo, constituyen uno de los grandes problemas cuando se diseñan estructuras utilizando paneles tipo "sandwich". Un nuevo tipo de panel "sandwich", configurado a partir de tejidos tridimensionales, está siendo desarrollado en la actualidad con el objetivo de eliminar esos problemas. Aunque el proceso de fabricación es muy simple, el panel "sandwich" obtenido es de estructura compleja, como resultado de la complejidad del tejido tridimensional utilizado. Este tejido tridimensional (3D es un tejido de fibra de vidrio producido en máquinas de tejer especializadas. La resistencia de las fibras verticales hace que, después de la impregnación con una resina, se mantenga la configuración tipo "sandwich". El resultado es un laminado de alta resistencia, gran rigidez y bajo peso. Sobre cada uno de los lados del panel "sandwich" se pueden

  9. Thermal conductivity of newspaper sandwiched aerated lightweight concrete panel

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Soon-Ching; Low, Kaw-Sai [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Jalan Genting Kelang, Setapak, 53300 Kuala Lumpur, Wilayah Persekutuan (Malaysia)

    2010-12-15

    Investigation on the thermal conductivity of newspaper sandwiched aerated lightweight concrete (ALC) panels is the main purpose of this study. Various densities of ALC panels ranging from 1700, 1400 and 1100 kg/m{sup 3} with three different aerial intensities of newspaper sandwiched were produced. Investigation was limited to the effect of aerial intensity of newspaper sandwiched and the effect of density of ALC on thermal conductivity. It is found that the thermal conductivity of newspaper sandwiched ALC panels reduced remarkably compared to control ALC panels. The reduction was recorded at 18.0%, 21.8% and 20.7% correspond to densities of 1700, 1400 and 1100 kg/m{sup 3} with just a mere 0.05 g/cm{sup 2} aerial intensity of newspaper sandwiched. Newspaper sandwiched has a significant impact on the performance of thermal conductivity of ALC panels based on regression analysis. (author)

  10. Mechanical evaluation with fe analysis of sandwich panels for wind turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Yasaswi, M.; Naveen, P.N.E.; Prasad, R.V. [GIET. Dept. of Mechanical Engineering, Rajahmundry (India)

    2012-07-01

    Sandwich panels are notable for their structural efficiency and are used as load bearing components in various branches of engineering, especially in aerospace and marine industries. The objective of the present work is to perform computer-aided analysis on sandwich panels. The analysis of sandwich panel with truss core are compared with other four types of sandwich panel with continuous corrugated core, top hat core, zed core and channel core. The basic reason to use sandwich structure is to save weight, however smooth skins and excellent fatigue resistance are also attributes of a sandwich structure. A sandwich is comprised of two layered composite materials formed by bonding two or more thin facings or face sheets to relatively thick core materials. In this type of construction the facings resist nearly all of the in-plane loads and out-of-plane bending moments. The thin facings provide nearly all of the bending stiffness because they are generally of a much higher modulus material is located at a greatest distance from the neutral axis of the component. The basic concept of sandwich panel is that the facings carry the bending loads and the core carries the shear loads. The main function of the core material is to distribute local loads and stresses over large areas. From all this analysis it is concluded that the truss core Sandwich panels can be used in wind turbine blade design. (Author)

  11. Non-linear Behavior of Curved Sandwich Panels

    DEFF Research Database (Denmark)

    Berggreen, Carl Christian; Jolma, P.; Karjalainen, J. P.

    2003-01-01

    In this paper the non-linear behavior of curved sandwich panels is investigated both numerically and experimentally. Focus is on various aspects of finite element modeling and calculation procedures. A simply supported, singly curved, CFRP/PVC sandwich panel is analyzed under uniform pressure load...

  12. Wave propagation in sandwich panels with a poroelastic core.

    Science.gov (United States)

    Liu, Hao; Finnveden, Svante; Barbagallo, Mathias; Arteaga, Ines Lopez

    2014-05-01

    Wave propagation in sandwich panels with a poroelastic core, which is modeled by Biot's theory, is investigated using the waveguide finite element method. A waveguide poroelastic element is developed based on a displacement-pressure weak form. The dispersion curves of the sandwich panel are first identified as propagating or evanescent waves by varying the damping in the panel, and wave characteristics are analyzed by examining their motions. The energy distributions are calculated to identify the dominant motions. Simplified analytical models are also devised to show the main physics of the corresponding waves. This wave propagation analysis provides insight into the vibro-acoustic behavior of sandwich panels lined with elastic porous materials.

  13. Analysis and Behaviour of Sandwich Panels with Profiled Metal Facings under Transverse Load

    Directory of Open Access Journals (Sweden)

    M. Budescu

    2004-01-01

    Full Text Available Sandwich panels with thin steel facings and polyurethane core combine the load-carrying capacity of metal facings and protection functions with core properties. The core separates the two facings and keeps them in a stable condition, transmits shear between external layers, provides most of the shear rigidity and occasionally makes of useful contribution to the bending stiffness of the sandwich construction as a whole [1]. An experimental program on sandwich panels has been organized to prove that the mechanical properties of core and interface satisfy the load-carrying requirements for structural sandwich panels. The analysis of sandwich panels with deep profiles facings for cladding elements, respectively the roof constructions, has been carried out according to the European design norms [1], [5].

  14. Mechanical properties and experimental researches of new CSIPs sandwich panels

    Directory of Open Access Journals (Sweden)

    Du Wenfeng

    2017-01-01

    Full Text Available The advantages of glass fiber reinforced composites (FRP and SIPs (structural insulated panels are combined, and a new type of sandwich panel called composite structural insulated panels (CSIPs is proposed. Through the adhesive bonding, CSIPs are made of FRP as face sheets and expanded polyethylene foam (EPS as a core. To master the mechanical characteristics of CSIPs, firstly, adopting the large deflection theory of Reissener in this paper derived the calculation formula of displacement and the stability critical load of CSIPs. Then, ANSYS software was used to carry on the analysis of finite element simulation. Finally, a testing piece of CSIP with length 1000mm and breath 1000mm was made and a test was done. The results show that the theoretical analysis results, finite element simulation results and test results are basically coincide. So the calculating formula of deformation and bearing capacity of CSIPs are correct. And CSIPs have the outstanding advantages of light weight and high strength.

  15. Vibroacoustic optimization of anti-tetrachiral and auxetic hexagonal sandwich panels with gradient geometry

    Science.gov (United States)

    Ranjbar, Mostafa; Boldrin, Luca; Scarpa, Fabrizio; Neild, Simon; Patsias, Sophoclis

    2016-05-01

    The work describes the vibroacoustic behavior of anti-tetrachiral and auxetic hexagonal gradient sandwich panels using homogenized finite element models to determine the mechanical properties of the auxetic structures, the natural frequencies and radiated sound power level of sandwich panels made by the auxetic cores. The mechanical properties and the vibroacoustic behavior of auxetic hexagonal sandwich panels are investigated as a benchmark. The radiated sound power level of the structure over the frequency range of 0-1000 Hz is minimized by modifying the core geometry of the gradient auxetic sandwich panels. Several excitation cases are considered. First-order and random optimization methods are used for the minimization of radiated sound power level of the structures. The results of this study present significant insights into the design of auxetic structures with respect to their vibroacoustical properties.

  16. Impact properties of aluminium - glass fiber reinforced plastics sandwich panels

    Directory of Open Access Journals (Sweden)

    Mathivanan Periasamy

    2012-06-01

    Full Text Available Aluminium - glass fiber reinforced plastics (GFRP sandwich panels are hybrid laminates consisting of GFRP bonded with thin aluminum sheets on either side. Such sandwich materials are increasingly used in airplane and automobile structures. Laminates with varying aluminium thickness fractions, fiber volume fractions and orientation in the layers of GFRP were fabricated by hand lay up method and evaluated for their impact performance by conducting drop weight tests under low velocity impacts. The impact energy required for initiating a crack in the outer aluminium layer as well as the energy required for perforation was recorded. The impact load-time history was also recorded to understand the failure behavior. The damage depth and the damage area were measured to evaluate the impact resistance. Optical photography and scanning electron micrographs were taken to visualize the crack and the damage zone. The bidirectional cross-ply hybrid laminate (CPHL has been found to exhibit better impact performance and damage resistance than the unidirectional hybrid laminate (UDHL. Increase in aluminium thickness fraction (Al tf and fiber volume fraction (Vf resulted in an increase in the impact energy required for cracking and perforation. On an overall basis, the sandwich panels exhibited better impact performance than the monolithic aluminium.

  17. Influences of impurities in recycled plastics on properties of PIM sandwich panels

    OpenAIRE

    Qi, K; Song, J.; Tarverdi, K

    2009-01-01

    Powder impression moulding (PIM) is a novel technology for manufacturing lightweight sandwich panels from plastics in powder form. The process is featured by its high tolerant to impurities or contaminants in the feedstock and thus requires much less materials segregation and cleaning operations when use recycled plastics. This paper investigate the influences of polymer impurities and soil contamination on structure and properties of PIM sandwich panels using compositions that simulate a PE-...

  18. Static and Fatigue Characterization of Nomex Honeycomb Sandwich Panels

    Directory of Open Access Journals (Sweden)

    Keskes Boualem

    2013-07-01

    Full Text Available The main benefits of using the sandwich concept in structural components are the high stiffness, good fatigue resistance and low weight ratios. Recent advances in materials and construction techniques have resulted in further improvement and increased uniformity of the sandwich composite properties. In order to use these materials in different applications, the knowledge of simply their static properties alone is not sufficient but additional information on their fatigue properties and durability are required. In this paper, first static and fatigue tests on four points bending of nomex honeycomb composite sandwich panels have been performed. Load/displacement and S-N fatigue curves are presented and analysed. Fatigue failure and damage modes are observed with an optical microscope and are discussed. The second is to address such fatigue behaviour by using a damage model and check it by experimentation. This fatigue damage model is based on stiffness degradation, which is used as a damage indicator. Two non-linear cumulative damage models derived from the chosen stiffness degradation equation are examined with assumption of linear Miner's damage summation. Predicted results are compared with available experimental data.

  19. Design and manufacturing of bio-based sandwich structures

    CSIR Research Space (South Africa)

    John, Maya J

    2017-03-01

    Full Text Available The aim of this chapter is to discuss the design and manufacturing of bio-based sandwich structures. As the economic advantages of weight reduction have become mandatory for many advanced industries, bio-based sandwich panels have emerged...

  20. Performance enhancement of sandwich panels with honeycomb–corrugation hybrid core

    Directory of Open Access Journals (Sweden)

    Bin Han

    2016-01-01

    Full Text Available The concept of combining metallic honeycomb with folded thin metallic sheets (corrugation to construct a novel core type for lightweight sandwich structures is proposed. The honeycomb–corrugation hybrid core is manufactured by filling the interstices of aluminum corrugations with precision-cut trapezoidal aluminum honeycomb blocks, bonded together using epoxy glue. The performance of such hybrid-cored sandwich panels subjected to out-of-plane compression, transverse shear, and three-point bending is investigated, both experimentally and numerically. The strength and energy absorption of the sandwich are dramatically enhanced, compared to those of a sandwich with either empty corrugation or honeycomb core. The enhancement is induced by the beneficial interaction effects of honeycomb blocks and folded panels on improved buckling resistance as well as altered crushing modes at large plastic deformation. The present approach provides an effective method to further improve the mechanical properties of conventional honeycomb-cored sandwich constructions with low relative densities.

  1. Two-dimensional analysis of shallow sandwich panels

    DEFF Research Database (Denmark)

    Skvortsov, V; Bozhevolnaya, Elena

    2001-01-01

    The shallow singly curved and rectangular in-plane sandwich panels affected by lateral loads are considered. The set of governing equations on the basis of the Timoshenko-Reissner plate theory is derived for these panels in the case of general boundary conditions. Usage of any real boundary...

  2. Residual Strength of In-plane Loaded Debonded Sandwich Panels

    DEFF Research Database (Denmark)

    Berggreen, Carl Christian; Simonsen, Bo Cerup

    2005-01-01

    This paper presents a FEM based numerical model for prediction of residual strength of damaged sandwich panels. As demonstrated, the model can predict the maximum load carrying capacity of real-life panels with debond damages, where the failure is governed by face-sheet buckling followed by debond...

  3. Residual Strength of In-plane Loaded Debonded Sandwich Panels

    DEFF Research Database (Denmark)

    Lundsgaard-Larsen, Christian; Nøkkentved, Alexandros; Berggreen, Carl Christian

    2005-01-01

    Face/core debond damaged sandwich panels exposed to uniform and non-uniform compression loads are studied experimentally. The panel geometry is full-scale rectangular with a centrally located circular prefabricated debond. The results show a considerable strength reduction with increasing debond...

  4. Friction stir welding (FSW of aluminium foam sandwich panels

    Directory of Open Access Journals (Sweden)

    M. Bušić

    2016-07-01

    Full Text Available The article focuses on the influence of welding speed and tool tilt angle upon the mechanical properties at the friction stir welding of aluminium foam sandwich panels. Double side welding was used for producing butt welds of aluminium sandwich panels applying insertion of extruded aluminium profile. Such insertion provided lower pressure of the tool upon the aluminium panels, providing also sufficient volume of the material required for the weldment formation. Ultimate tensile strength and flexural strength for three-point bending test have been determined for samples taken from the welded joints. Results have confirmed anticipated effects of independent variables.

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

    Science.gov (United States)

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

    2014-05-01

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

  6. Structural and failure mechanics of sandwich composites

    CERN Document Server

    Carlsson, LA; Carlsson, Leif A

    2011-01-01

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

  7. A Robust Multifunctional Sandwich Panel Design with Trabecular Structures by the Use of Additive Manufacturing Technology for a New De-Icing System

    Directory of Open Access Journals (Sweden)

    Carlo Giovanni Ferro

    2017-06-01

    Full Text Available Anti-ice systems assure a vital on-board function in most aircraft: ice prevention or de-icing is mandatory for all aerodynamic surfaces to preserve their performance, and for all the movable surfaces to allow the proper control of the plane. In this work, a novel multi-functional panel concept which integrates anti-icing directly inside the primary structure is presented. In fact, constructing the core of the sandwich with trabecular non-stochastic cells allows the presence of a heat exchanger directly inside the structure with a savings in weight and an improvement in thermal efficiency. This solution can be realized easily in a single-piece component using Additive Manufacturing (AM technology without the need for joints, gluing, or welding. The objective of this study is to preliminarily investigate the mechanical properties of the core constructed with Selective Laser Melting (SLM; through the Design of Experiment (DOE, different design parameters were varied to understand how they affect the compression behaviour.

  8. Development of a finite element model for the simulation of parabolic impact of sandwich panels

    Directory of Open Access Journals (Sweden)

    Ramakrishnan Karthik Ram

    2015-01-01

    Full Text Available Sandwich panels are lightweight structures of two thin high strength facesheets bonded to either side of a thick low density core such as foams and honeycombs. It is necessary to study the impact response of sandwich structures in order to ensure the reliability and safety of these structures. The response of sandwich panels to impact loading is usually studied for impact at normal angle of incidence. In real engineering situations, the structures are more frequently loaded at some oblique angle or with a complex trajectory. It is easy to carry out normal impact tests using devices like the drop tower, but impacts at oblique angles are difficult to characterise experimentally. A tri-dimensional impact device called Hexapod has been developed to experimentally study the impact loading of sandwich plates with a parabolic trajectory. The Hexapod is a modified Gough-Stewart platform that can be moved independently in the six degrees of freedom, corresponding to three translation axes and three rotation axes. In this paper, an approach for modelling the parabolic impact of sandwich structures with thin metallic facesheets and polymer foam core using commercial finite element code LS-DYNA software is presented. The results of the FE model of sandwich panels are compared with experimental data in terms of the time history of vertical and horizontal components of force. A comparison of the strain history obtained from Digital Image Correlation and LS-Dyna model are also presented.

  9. Thermo-mechanical interaction effects in foam cored sandwich panels-correlation between High-order models and Finite element analysis results

    DEFF Research Database (Denmark)

    Palleti, Hara Naga Krishna Teja; Santiuste, Carlos; Thomsen, Ole Thybo

    2010-01-01

    Thermo-mechanical interaction effects including thermal material degradation in polymer foam cored sandwich structures is investigated using the commercial Finite Element Analysis (FEA) package ABAQUS/Standard. Sandwich panels with different boundary conditions in the form of simply supported...

  10. Sound transmission analysis of partially treated MR fluid-based sandwich panels using finite element method

    Science.gov (United States)

    Hemmatian, M.; Sedaghati, R.

    2017-04-01

    This study aims at developing a finite element model to predict the sound transmission loss (STL) of a multilayer panel partially treated with a Magnetorheological (MR) fluid core layer. MR fluids are smart materials with promising controllable rheological characteristics in which the application of an external magnetic field instantly changes their rheological properties. Partial treatment of sandwich panels with MR fluid core layer provides an opportunity to change stiffness and damping of the structure without significantly increasing the mass. The STL of a finite sandwich panel partially treated with MR fluid is modeled using the finite element (FE) method. Circular sandwich panels with clamped boundary condition and elastic face sheets in which the core layer is segmented circumferentially is considered. The MR fluid core layer is considered as a viscoelastic material with complex shear modulus with the magnetic field and frequency dependent storage and loss moduli. Neglecting the effect of the panel's vibration on the pressure forcing function, the work done by the acoustic pressure is expressed as a function of the blocked pressure in order to calculate the force vector in the equation of the motion of the panel. The governing finite element equation of motion of the MR sandwich panel is then developed to predict the transverse vibration of the panel which can then be utilized to obtain the radiated sound using Green's function. The developed model is used to conduct a systematic parametric study on the effect of different locations of MR fluid treatment on the natural frequencies and the STL.

  11. On the use of a woven mat to control the crack path in composite sandwich structures

    DEFF Research Database (Denmark)

    Lundsgaard-Larsen, Christian; Berggreen, Christian; Carlsson, Leif A.

    2008-01-01

    In the last couple of decades the use of sandwich structures has increased tremendously in applications where low weight is of importance e.g. ship structures, where sandwich panels are often built from fiber reinforced faces and foam cores. An important damage type in sandwich structures is sepa...

  12. Effect of microencapsulated phase change material in sandwich panels

    Energy Technology Data Exchange (ETDEWEB)

    Castellon, Cecilia; Medrano, Marc; Roca, Joan; Cabeza, Luisa F. [GREA Innovacio Concurrent, Edifici CREA, Universitat de Lleida, Pere de Cabrera s/n, 25001 Lleida (Spain); Navarro, Maria E.; Fernandez, Ana I. [Departamento de Ciencias de los Materiales e Ingenieria Metalurgica, Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); Lazaro, Ana; Zalba, Belen [Instituto de Investigacion en Ingenieria de Aragon, I3A, Grupo de Ingenieria Termica y Sistemas Energeticos (GITSE), Dpto. Ingenieria Mecanica, Area de Maquinas y Motores Termicos, Universidad de Zaragoza, Campus Politecnico Rio Ebro, Edificio ' ' Agustin de Betancourt,' ' Maria de Luna s/n, 50018 Zaragoza (Spain)

    2010-10-15

    Sandwich panels are a good option as building materials, as they offer excellent characteristics in a modular system. The goal of this study was to demonstrate the feasibility of using the microencapsulated PCM (Micronal BASF) in sandwich panels to increase their thermal inertia and to reduce the energy demand of the final buildings. In this paper, to manufacture the sandwich panel with microencapsulated PCM three different methods were tested. In case 1, the PCM was added mixing the microencapsulated PCM with one of the components of the polyurethane. In the other two cases, the PCM was added either a step before (case 2) or a step after (case 3) to the addition of the polyurethane to the metal sheets. The results show that in case 1 the effect of PCM was overlapped by a possible increase in thermal conductivity, but an increase of thermal inertia was found in case 3. In case 2, different results were obtained due to the poor distribution of the PCM. Some samples showed the effect of the PCM (higher thermal inertia), and other samples results were similar to the conventional sandwich panel. In both cases (2 and 3), it is required to industrialize the process to improve the results. (author)

  13. Simulation of Prestressed Concrete Sandwich Panels Subjected to Blast Loads (Preprint)

    Science.gov (United States)

    2010-02-01

    AFRL-RX-TY-TP-2010-0014 PREPRINT SIMULATION OF PRESTRESSED CONCRETE SANDWICH PANELS SUBJECTED TO BLAST LOADS Charles M. Newberry and...NUMBER (Include area code) 01-FEB-2010 Conference Paper PREPRINT 01-JAN-2009-- 31-DEC-2009 Simulation of Prestressed Concrete Sandwich Panels Subjected... concrete , sandwich panels, simulation, LS-DYNA, blast, tilt-up panels U U U UU 14 Paul Sheppard Reset Simulation of Prestressed Concrete Sandwich

  14. Non-Uniform Compressive Strength of Debonded Sandwich Panels

    DEFF Research Database (Denmark)

    Berggreen, Carl Christian; Simonsen, Bo Cerup

    2005-01-01

    This article describes the development, validation and application of a FEM based numerical model for prediction of residual strength of damaged sandwich panels. The core of the theoretical method is a newly developed procedure for prediction of the propagation of a face-core debond. As demonstra......This article describes the development, validation and application of a FEM based numerical model for prediction of residual strength of damaged sandwich panels. The core of the theoretical method is a newly developed procedure for prediction of the propagation of a face-core debond.......(2005)., shows that the model is indeed able to predict the failure modes and the residual strength of damaged panels with accuracy sufficient for practical applications. This opens up for a number of important engineering applications, for example risk-based inspection and repair schemes....

  15. Spacecraft Shielding: An Experimental Comparison Between Open Cell Aluminium Foam Core Sandwich Panel Structures and Whipple Shielding.

    Science.gov (United States)

    Pasini, D. L. S.; Price, M. C.; Burchell, M. J.; Cole, M. J.

    2013-09-01

    Spacecraft shielding is generally provided by metallic plates in a Whipple shield type configuration [1] where possible. However, mission restrictions such as spacecraft payload mass, can prevent the inclusion of a dedicated protective structure for prevention against impact damage from micrometeoroids. Due to this, often the spacecraft's primary structure will act as the de facto shield. This is commonly an aluminium honeycomb backed with either glass fibre reinforced plastic (GFRP) or aluminium faceplates [2]. Such materials are strong, lightweight and relatively cheap due to their abundance used within the aerospace industry. However, these materials do not offer the best protection (per unit weight) against hypervelocity impact damage. A new material for shielding (porous aluminium foam [3]) is suggested for low risk space missions. Previous studies by NASA [4] have been performed to test this new material against hypervelocity impacts using spherical aluminium projectiles. This showed its potential for protection for satellites in Earth orbit, against metallic space debris. Here we demonstrate the material's protective capabilities against micrometeoroids, using soda-lime glass spheres as projectiles to accurately gauge its potential with relation to silicatious materials, such as micrometeoroids and natural solar system debris. This is useful for spacecraft missions beyond Earth orbit where solar system materials are the dominant threat (via hypervelocity impacts) to the spacecraft, rather than manmade debris.

  16. Optimization process for thin-walled high performance concrete sandwich panels

    DEFF Research Database (Denmark)

    Hodicky, Kamil; Hulin, Thomas; Schmidt, Jacob Wittrup

    2014-01-01

    economical solution. The present paper aims to provide multi-objective optimisation procedure addressed to structural precast thin-walled High Performance Concrete Sandwich Panels (HPCSP). The research aim is concerned with developing a tool that considers the cost of HPCSP materials along...

  17. Optimization process for thin-walled High Performance Concrete sandwich panels

    DEFF Research Database (Denmark)

    Hodicky, Kamil; Hulin, Thomas; Schmidt, Jacob Wittrup

    2013-01-01

    economical solu-tion. The present paper aims to provide multi-objective optimisation procedure addressed to structural precast thin-walled High Performance Concrete Sandwich Panels (HPCSP). The research aim is concerned with de-veloping a tool that considers the cost of HPCSP materials along...

  18. Localized Effects in the Nonlinear Behavior of Sandwich Panels with a Transversely Flexible Core

    DEFF Research Database (Denmark)

    Frostig, Y.; Thomsen, Ole Thybo

    2005-01-01

    This paper presents the results of an investigation of the role of localized effects within the geometrically nonlinear domain on structural sandwich panels with a "compliant" core. Special emphasis is focused on the nonlinear response near concentrated loads and stiffened core regions. The adopt...

  19. A More Sustainable Way for Producing RC Sandwich Panels On-Site and in Developing Countries

    Directory of Open Access Journals (Sweden)

    Lorenzo Graziani

    2017-03-01

    Full Text Available The purpose of this work is to assess if traditionally used welded connectors for joining the two skins of reinforced concrete (RC sandwich panels, used as structural walls and horizontal structural elements, can be substituted with bent ones. In this way, the scope of the effort is to reduce drastically the energy required during manufacturing, thus having a much more sustainable building product. Wire mesh on site production, in fact, requires a large amount of energy for the welding process, as stated by several Environmental Product Declaration (EPD. In addition, the production of sandwich panels with bent connectors requires a low level of automation and no qualified labor allowing the diffusion in developing countries. The procedures used to execute the work were both experimental and numerical. Structural performances were examined by testing full-scale sandwich panels under (axial and eccentric compression and flexural loads. Additionally, a Finite Element (FE study was developed to investigate and to optimize the dimension of welded mesh and the number of connectors. The major findings show that it is possible to substitute welded connectors with bent ones without compromising the structural performance of the tested RC sandwich panels, thus having a more sustainable way for producing these last ones.

  20. Static and Fatigue Characterization of Nomex Honeycomb Sandwich Panels

    OpenAIRE

    Boualem, Keskes

    2013-01-01

    The main benefits of using the sandwich concept in structural components are the high stiffness, good fatigue resistance and low weight ratios. Recent advances in materials and construction techniques have resulted in further improvement and increased uniformity of the sandwich composite properties. In order to use these materials in different applications, the knowledge of simply their static properties alone is not sufficient but additional information on their fatigue properties and durabi...

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

    Science.gov (United States)

    McGowan, David M.; Ambur, Damodar R.

    1997-01-01

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

  2. Behavior of sandwich panels subjected to bending fatigue, axial compression loading and in-plane bending

    Science.gov (United States)

    Mathieson, Haley Aaron

    This thesis investigates experimentally and analytically the structural performance of sandwich panels composed of glass fibre reinforced polymer (GFRP) skins and a soft polyurethane foam core, with or without thin GFRP ribs connecting skins. The study includes three main components: (a) out-of-plane bending fatigue, (b) axial compression loading, and (c) in-plane bending of sandwich beams. Fatigue studies included 28 specimens and looked into establishing service life (S-N) curves of sandwich panels without ribs, governed by soft core shear failure and also ribbed panels governed by failure at the rib-skin junction. Additionally, the study compared fatigue life curves of sandwich panels loaded under fully reversed bending conditions (R=-1) with panels cyclically loaded in one direction only (R=0) and established the stiffness degradation characteristics throughout their fatigue life. Mathematical models expressing fatigue life and stiffness degradation curves were calibrated and expanded forms for various loading ratios were developed. Approximate fatigue thresholds of 37% and 23% were determined for non-ribbed panels loaded at R=0 and -1, respectively. Digital imaging techniques showed significant shear contribution significantly (90%) to deflections if no ribs used. Axial loading work included 51 specimens and examined the behavior of panels of various lengths (slenderness ratios), skin thicknesses, and also panels of similar length with various rib configurations. Observed failure modes governing were global buckling, skin wrinkling or skin crushing. In-plane bending involved testing 18 sandwich beams of various shear span-to-depth ratios and skin thicknesses, which failed by skin wrinkling at the compression side. The analytical modeling components of axially loaded panels include; a simple design-oriented analytical failure model and a robust non-linear model capable of predicting the full load-displacement response of axially loaded slender sandwich panels

  3. Experimental study on mechanical properties of aircraft honeycomb sandwich structures

    Directory of Open Access Journals (Sweden)

    Talebi Mazraehshahi H.

    2010-06-01

    Full Text Available Mechanical behaviour of sandwich panels under different conditions have been exprimentally studied in this research to increase the knowledge of aircraft sandwich panel structures and facilitate design criteria for aircraft structures. Tests were concentrated on the honeycomb sandwich structures under different loads including flexural, insert shear, flat wise tension and compression loads. Furthermore, effect of core density and face material on mechanical behavior of different samples were investigated and compared with analytical and FEM method. Effects of skin thickness on strength of honycomb sandwhich panels under shear pull out and moments have also been considerd in this study. According to this investigation, insert strength and flexural test under different load conditions is strongly affected by face thickness, but compression and tearoff (falt wise tensile properties of a sandwich panel depends on core material. The study concludes that the correlation between experimental results and the analytical predictions will enable the designer to predict the mechanical behaviour and strength of a sandwich beam; however, applied formula may lead engineers to unreliable results for shear modulus.

  4. Sound Transmission Loss Through a Corrugated-Core Sandwich Panel with Integrated Acoustic Resonators

    Science.gov (United States)

    Schiller, Noah H.; Allen, Albert R.; Zalewski, Bart F; Beck, Benjamin S.

    2014-01-01

    The goal of this study is to better understand the effect of structurally integrated resonators on the transmission loss of a sandwich panel. The sandwich panel has facesheets over a corrugated core, which creates long aligned chambers that run parallel to the facesheets. When ports are introduced through the facesheet, the long chambers within the core can be used as low-frequency acoustic resonators. By integrating the resonators within the structure they contribute to the static load bearing capability of the panel while also attenuating noise. An analytical model of a panel with embedded resonators is derived and compared with numerical simulations. Predictions show that acoustic resonators can significantly improve the transmission loss of the sandwich panel around the natural frequency of the resonators. In one configuration with 0.813 m long internal chambers, the diffuse field transmission loss is improved by more than 22 dB around 104 Hz. The benefit is achieved with no added mass or volume relative to the baseline structure. The embedded resonators are effective because they radiate sound out-of-phase with the structure. This results in destructive interference, which leads to less transmitted sound power.

  5. Research on Transient Liquid Phase Diffusion Bonding of Steel Sandwich Panels Under Small Plastic Deformation

    Science.gov (United States)

    Li, H.; Li, Z. X.

    2008-12-01

    Plastic deformation was newly introduced in transient liquid phase (TLP) diffusion bonding of steel sandwich panels. The effect of plastic deformation on bonding strength was investigated through lab experiments. It was assumed that three factors, including newly generated metal surface area, deformation heat, and lattice distortion, contribute to the acceleration of interface atoms diffusion and increase of diffusion coefficients. A numerical model of isothermal solidification time was developed for TLP bonding process under plastic deformation and applied to carbon steel sandwich panels bonding with copper interlayer. A reasonable isothermal solidification time was obtained when an effective diffusion coefficient was used. Based on lab experiments, the effects of plastic deformation on interlayer film thickness and isothermal solidification time were studied through theoretical calculation with the new model. The evolution of interlayer film thickness indicates a good agreement between the calculation and experimental measurement. The results show that the isothermal solidification time is obviously reduced due to the effect of plastic deformation. Furthermore, a new steel sandwich cooling panel for heat exchanger was fabricated by TLP diffusion bonding under 13.1% plastic deformation. The test results suggest that a steel sandwich panel of inequidistant fin structure can provide enhanced heat transfer efficiency.

  6. Experimental investigations of sandwich panels using high performance concrete thin plates exposed to fire

    DEFF Research Database (Denmark)

    Hulin, Thomas; Hodicky, Kamil; Schmidt, Jacob Wittrup

    2015-01-01

    Structural sandwich panels using thin high performance concrete (HPC) plates offer a possibility to address the modern environmental challenges faced by the construction industry. Fire resistance is a major necessity in structures using HPC. This paper presents experimental studies at elevated...... temperatures for panels with 30 mm thick plates stiffened by structural ribs, thick insulation layers, and steel shear connecting systems. Parametric variation assessing the role of each component of the sandwich structure was performed on unloaded specimens of reduced size. Full size walls were tested...... plate and one of them experienced heavy heat-induced spalling. Results highlighted insulation shear failure from differential thermal expansion at the interface with concrete. It suggests the existence of a high bond level between the two materials which might allow structural applications at early age...

  7. Sandwich Structured Composites for Aeronautics: Methods of Manufacturing Affecting Some Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Aneta Krzyżak

    2016-01-01

    Full Text Available Sandwich panels are composites which consist of two thin laminate outer skins and lightweight (e.g., honeycomb thick core structure. Owing to the core structure, such composites are distinguished by stiffness. Despite the thickness of the core, sandwich composites are light and have a relatively high flexural strength. These composites have a spatial structure, which affects good thermal insulator properties. Sandwich panels are used in aeronautics, road vehicles, ships, and civil engineering. The mechanical properties of these composites are directly dependent on the properties of sandwich components and method of manufacturing. The paper presents some aspects of technology and its influence on mechanical properties of sandwich structure polymer composites. The sandwiches described in the paper were made by three different methods: hand lay-up, press method, and autoclave use. The samples of sandwiches were tested for failure caused by impact load. Sandwiches prepared in the same way were used for structural analysis of adhesive layer between panels and core. The results of research showed that the method of manufacturing, more precisely the pressure while forming sandwich panels, influences some mechanical properties of sandwich structured polymer composites such as flexural strength, impact strength, and compressive strength.

  8. Morphing nacelle inlet lip with pneumatic actuators and a flexible nano composite sandwich panel

    Science.gov (United States)

    Gulsine Ozdemir, Nazli; Scarpa, Fabrizio; Craciun, Monica; Remillat, Chrystel; Lira, Cristian; Jagessur, Yogesh; Da Rocha-Schmidt, Luiz

    2015-12-01

    We present a hybrid pneumatic/flexible sandwich structure with thermoplastic (TP) nanocomposite skins to enable the morphing of a nacelle inlet lip. The design consists of pneumatic inflatables as actuators and a flexible sandwich panel that morphs under variable pressure combinations to adapt different flight conditions and save fuel. The sandwich panel forms the outer layer of the nacelle inlet lip. It is lightweight, compliant and impact resistant with no discontinuities, and consists of graphene-doped thermoplastic polyurethane (G/TPU) skins that are supported by an aluminium Flex-core honeycomb in the middle, with near zero in-plane Poisson’s ratio behaviour. A test rig for a reduced-scale demonstrator was designed and built to test the prototype of morphing nacelle with custom-made pneumatic actuators. The output force and the deflections of the experimental demonstrator are verified with the internal pressures of the actuators varying from 0 to 0.41 MPa. The results show the feasibility and promise of the hybrid inflatable/nanocomposite sandwich panel for morphing nacelle airframes.

  9. Evaluation of Shear Tie Connectors for Use in Insulated Concrete Sandwich Panels

    Science.gov (United States)

    2009-12-01

    of non-load bearing precast/ prestressed or tilt-up concrete sandwich wall panels (WP) are examined. These components are used extensively in modern... prestress wall panels, precast wall panels, tilt-up wall panels, concrete insulted wall systems U U U UU 37 Paul Sheppard Reset i Table of...illustrate this concept, the blast resistances of non-load bearing precast/ prestressed or tilt-up concrete sandwich wall panels were examined. These

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

    Science.gov (United States)

    Ko, William L.; Jackson, Raymond H.

    1992-01-01

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

  11. Multiscale Finite-Element Modeling of Sandwich Honeycomb Composite Structures

    Directory of Open Access Journals (Sweden)

    Yu. I. Dimitrienko

    2014-01-01

    Full Text Available The paper presents a developed multi-scale model of sandwich honeycomb structures. The model allows us both to calculate effective elastic-strength characteristics of honeycomb and forced covering of sandwich, and to find a 3D stress-strain state of structures using the threedimensional elastic theory for non- homogeneous media. On the basis of finite element analysis it is shown, that under four-point bending the maximal value of bending and shear stresses in the sandwich honeycomb structures are realized in the zone of applied force and plate support. Here the local stress maxima approximately 2-3 times exceed the “engineering” theoretical plate values of bending and shear stresses in the middle of panel. It is established that at tests for fourpoint bending there is a failure of the honeycomb sandwich panels because of the local adhesion failure rather than because of the covering exfoliation off the honeycomb core in the middle of panel.

  12. Dynamic response and optimal design of curved metallic sandwich panels under blast loading.

    Science.gov (United States)

    Qi, Chang; Yang, Shu; Yang, Li-Jun; Han, Shou-Hong; Lu, Zhen-Hua

    2014-01-01

    It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA) steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a "soft" outer face and a "hard" inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD) and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA) and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN) metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances.

  13. Dynamic Response and Optimal Design of Curved Metallic Sandwich Panels under Blast Loading

    Directory of Open Access Journals (Sweden)

    Chang Qi

    2014-01-01

    Full Text Available It is important to understand the effect of curvature on the blast response of curved structures so as to seek the optimal configurations of such structures with improved blast resistance. In this study, the dynamic response and protective performance of a type of curved metallic sandwich panel subjected to air blast loading were examined using LS-DYNA. The numerical methods were validated using experimental data in the literature. The curved panel consisted of an aluminum alloy outer face and a rolled homogeneous armour (RHA steel inner face in addition to a closed-cell aluminum foam core. The results showed that the configuration of a “soft” outer face and a “hard” inner face worked well for the curved sandwich panel against air blast loading in terms of maximum deflection (MaxD and energy absorption. The panel curvature was found to have a monotonic effect on the specific energy absorption (SEA and a nonmonotonic effect on the MaxD of the panel. Based on artificial neural network (ANN metamodels, multiobjective optimization designs of the panel were carried out. The optimization results revealed the trade-off relationships between the blast-resistant and the lightweight objectives and showed the great use of Pareto front in such design circumstances.

  14. Vibroacoustic Characterization of Corrugated-Core and Honeycomb-Core Sandwich Panels

    Science.gov (United States)

    Allen, Albert; Schiller, Noah

    2016-01-01

    The vibroacoustic characteristics of two candidate launch vehicle fairing structures, corrugated- core and honeycomb-core sandwich designs, were studied. The study of these structures has been motivated by recent risk reduction efforts focused on mitigating high noise levels within the payload bays of large launch vehicles during launch. The corrugated-core sandwich concept is of particular interest as a dual purpose structure due to its ability to harbor resonant noise control systems without appreciably adding mass or taking up additional volume. Specifically, modal information, wavelength dispersion, and damping were determined from a series of vibrometer measurements and subsequent analysis procedures carried out on two test panels. Numerical and analytical modeling techniques were also used to assess assumed material properties and to further illuminate underlying structural dynamic aspects. Results from the tests and analyses described herein may serve as a reference for additional vibroacoustic studies involving these or similar structures.

  15. Precast/Prestressed Concrete Experiments Performance on Non-Load Bearing Sandwich Wall Panels

    Science.gov (United States)

    2011-01-01

    AFRL-RX-TY-TR-2011-0021 PRECAST/ PRESTRESSED CONCRETE EXPERIMENTS PERFORMANCE ON NON-LOAD BEARING SANDWICH WALL PANELS Clay J. Naito...2008 -- 20-NOV-2010 Precast/ Prestressed Concrete Experiments Performance on Non-Loadbearing Sandwich Wall Panels FA8903-08-D-8768-0002 99999F GOVT F0...Wall Construction [TCA 2006] .............................................. 5 3. Prestressed Concrete Sandwich Wall Construction [PCI 1997

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

    Science.gov (United States)

    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

  17. Thermal Performance of Precast Concrete Sandwich Panel (PCSP) Design for Sustainable Built Environment

    Science.gov (United States)

    Ern, Peniel Ang Soon; Ling, Lim Mei; Kasim, Narimah; Hamid, Zuhairi Abd; Masrom, Md Asrul Nasid Bin

    2017-10-01

    Malaysia’s awareness of performance criteria in construction industry towards a sustainable built environment with the use of precast concrete sandwich panel (PCSP) system is applied in the building’s wall to study the structural behaviour. However, very limited studies are conducted on the thermal insulation of exterior and interior panels in PCSP design. In hot countries such as Malaysia, proper designs of panel are important to obtain better thermal insulation for building. This study is based on thermal performance of precast concrete sandwich panel design for sustainable built environment in Malaysia. In this research, three full specimens, which are control specimen (C), foamed concrete (FC) panels and concrete panels with added palm oil fuel ash (FC+ POFA), where FC and FC+POFA sandwiched with gypsum board (G) were produced to investigate their thermal performance. Temperature difference of exterior and interior surface of specimen was used as indicators of thermal-insulating performance of PCSP design. Heat transfer test by halogen lamp was carried out on three specimens where the exterior surface of specimens was exposed to the halogen lamp. The temperature reading of exterior and interior surface for three specimens were recorded with the help of thermocouple. Other factors also studied the workability, compressive strength and axial compressive strength of the specimens. This study has shown that FC + POFA specimen has the strength nearer to normal specimen (C + FC specimen). Meanwhile, the heat transfer results show that the FC+POFA has better thermal insulation performance compared to C and FC specimens with the highest temperature difference, 3.4°C compared to other specimens. The results from this research are useful to be implemented in construction due to its benefits such as reduction of energy consumption in air-conditioning, reduction of construction periods and eco-friendly materials.

  18. Experimental study of acoustical characteristics of honeycomb sandwich structures

    Science.gov (United States)

    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. Full-scale performance assessment of aircraft secondary sandwich structure using thermoelastic stress analysis

    OpenAIRE

    Crump, D.A.; Dulieu-Barton, J.M.; Savage, J

    2009-01-01

    The use of resin film infusion (RFI) has been proven to reduce the cost of production of aircraft secondary sandwich structure. In this paper thermoelastic stress analysis (TSA) is used to assess the performance of full scale aircraft sandwich structure panels produced using both the conventional autoclave process and RFI. Finite element (FE) models of both panel types are developed and TSA is used to validate the models.

  20. Vibro-acoustics of lightweight sandwich structures

    CERN Document Server

    Lu, Tianjian

    2014-01-01

    Vibro-Acoustics of Lightweight Sandwich Structures introduces the study of the coupled vibration and acoustic behavior of lightweight sandwich structures in response to harmonic force and sound pressure. This book focuses on the theoretical modeling and experimental investigation of lightweight sandwich structures in order to provide a predictive framework for vibro-acoustic characteristics of typical engineering structures. Furthermore, by developing solution tools, it concentrates on the influence of key systematic parameters leading to effective guidance for optimal structure design toward lightweight, high-stiffness and superior sound insulation capability. This book is intended for researchers, scientists, engineers and graduate students in mechanical engineering especially in structural mechanics, mechanics and acoustics. Fengxian Xin and Tianjian Lu both work at the School of Aerospace, Xi’an Jiaotong University.

  1. Modeling of Sensor Placement Strategy for Shape Sensing and Structural Health Monitoring of a Wing-Shaped Sandwich Panel Using Inverse Finite Element Method

    Directory of Open Access Journals (Sweden)

    Adnan Kefal

    2017-11-01

    Full Text Available This paper investigated the effect of sensor density and alignment for three-dimensional shape sensing of an airplane-wing-shaped thick panel subjected to three different loading conditions, i.e., bending, torsion, and membrane loads. For shape sensing analysis of the panel, the Inverse Finite Element Method (iFEM was used together with the Refined Zigzag Theory (RZT, in order to enable accurate predictions for transverse deflection and through-the-thickness variation of interfacial displacements. In this study, the iFEM-RZT algorithm is implemented by utilizing a novel three-node C°-continuous inverse-shell element, known as i3-RZT. The discrete strain data is generated numerically through performing a high-fidelity finite element analysis on the wing-shaped panel. This numerical strain data represents experimental strain readings obtained from surface patched strain gauges or embedded fiber Bragg grating (FBG sensors. Three different sensor placement configurations with varying density and alignment of strain data were examined and their corresponding displacement contours were compared with those of reference solutions. The results indicate that a sparse distribution of FBG sensors (uniaxial strain measurements, aligned in only the longitudinal direction, is sufficient for predicting accurate full-field membrane and bending responses (deformed shapes of the panel, including a true zigzag representation of interfacial displacements. On the other hand, a sparse deployment of strain rosettes (triaxial strain measurements is essentially enough to produce torsion shapes that are as accurate as those of predicted by a dense sensor placement configuration. Hence, the potential applicability and practical aspects of i3-RZT/iFEM methodology is proven for three-dimensional shape-sensing of future aerospace structures.

  2. Modeling of Sensor Placement Strategy for Shape Sensing and Structural Health Monitoring of a Wing-Shaped Sandwich Panel Using Inverse Finite Element Method.

    Science.gov (United States)

    Kefal, Adnan; Yildiz, Mehmet

    2017-11-30

    This paper investigated the effect of sensor density and alignment for three-dimensional shape sensing of an airplane-wing-shaped thick panel subjected to three different loading conditions, i.e., bending, torsion, and membrane loads. For shape sensing analysis of the panel, the Inverse Finite Element Method (iFEM) was used together with the Refined Zigzag Theory (RZT), in order to enable accurate predictions for transverse deflection and through-the-thickness variation of interfacial displacements. In this study, the iFEM-RZT algorithm is implemented by utilizing a novel three-node C°-continuous inverse-shell element, known as i3-RZT. The discrete strain data is generated numerically through performing a high-fidelity finite element analysis on the wing-shaped panel. This numerical strain data represents experimental strain readings obtained from surface patched strain gauges or embedded fiber Bragg grating (FBG) sensors. Three different sensor placement configurations with varying density and alignment of strain data were examined and their corresponding displacement contours were compared with those of reference solutions. The results indicate that a sparse distribution of FBG sensors (uniaxial strain measurements), aligned in only the longitudinal direction, is sufficient for predicting accurate full-field membrane and bending responses (deformed shapes) of the panel, including a true zigzag representation of interfacial displacements. On the other hand, a sparse deployment of strain rosettes (triaxial strain measurements) is essentially enough to produce torsion shapes that are as accurate as those of predicted by a dense sensor placement configuration. Hence, the potential applicability and practical aspects of i3-RZT/iFEM methodology is proven for three-dimensional shape-sensing of future aerospace structures.

  3. Combined shear/compression structural testing of asymmetric sandwich structures

    OpenAIRE

    Castanié, Bruno; Barrau, Jean-Jacques; Jaouen, Jean-Pierre; Rivallant, Samuel

    2004-01-01

    Asymmetric sandwich technology can be applied in the design of lightweight, non-pressurized aeronautical structures such as those of helicopters. A test rig of asymmetric sandwich structures subjected to compression/shear loads was designed, validated, and set up. It conforms to the standard certification procedure for composite aeronautical structures set out in the “test pyramid”, a multiscale approach. The static tests until failure showed asymmetric sandwich structures to be extremely res...

  4. Design and Testing of Sandwich Structures with Different Core Materials

    Directory of Open Access Journals (Sweden)

    Henrik HERRANEN

    2012-03-01

    Full Text Available The purpose of this study was to design a light-weight sandwich panel for trailers. Strength calculations and selection of different materials were carried out in order to find a new solution for this specific application. The sandwich materials were fabricated using vacuum infusion technology. The different types of sandwich composite panels were tested in 4-point bending conditions according to ASTM C393/C393M. Virtual testing was performed by use of ANSYS software to simplify the core material selection process and to design the layers. 2D Finite element analysis (FEA of 4-point bending was made with ANSYS APDL (Classic software. Data for the FEA was obtained from the tensile tests of glass fiber plastic (GFRP laminates. Virtual 2D results were compared with real 4-point bending tests.  3D FEA was applied to virtually test the selected sandwich structure in real working conditions. Based on FEA results the Pareto optimality concept has been applied and optimal solutions determined.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1340

  5. Ageing tests study on wood-based sandwich panels

    Directory of Open Access Journals (Sweden)

    Mateo, Raquel

    2011-12-01

    Full Text Available Composite lightweight wood panels are being increasingly used in construction in Spain. Their growing use should be accompanied by necessary guarantees based on studies of their properties. As it is prescriptive and in addition to others tests, in the present work is examinated the durability of these panels when exposed to the climatic conditions, a characteristic of great importance for wood products, according to Guide ETAG 016, the current standard defining the ageing tests to be used. However, due to the use class of this material, there are indications that the testing outlined in this Guide is inappropriate for assessing the ageing of wood-based sandwich panels. Alternative tests are here proposed that recreate rather better the real conditions under which these products are used. Covering the samples in a waterproof sheeting permeable to the outward movement of water vapour, which is in fact used in the installation, provided the best procedure for testing these panels.

    Los paneles sándwich de madera son un producto de creciente aplicación en la edificación de nuestro país. Este ascendente uso del material debe estar acompañado de las garantías necesarias avaladas por un estudio previo de sus prestaciones. Como es preceptivo y entre otros, se evalúa su durabilidad frente a las condiciones climatológicas, clave en los productos derivados de la madera, acorde a la normativa actual definida con tal fin, la Guía ETAG 016. Sin embargo, debido a la clase de uso del material, se ha detectado que dicha normativa tal y como está concebida no es capaz de valorar su envejecimiento adecuadamente. En este trabajo se proponen ensayos alternativos al establecido tras exhaustivos análisis que recrean las condiciones reales de uso y más acordes a los productos de madera. Se concluye que la incorporación de una lámina impermeable pero permeable al vapor de agua hacia el exterior, como las utilizadas en el montaje, aportan el mejor

  6. Ultra-Light Asymmetric Photovoltaic Sandwich Structures

    OpenAIRE

    Rion, J.; Leterrier, Y.; Månson, J.-A. E.; Blairon, Jean-Marie

    2009-01-01

    This work evaluated the possibility of using silicon solar cells as load-carrying elements in composite sandwich structures. Such an ultra-light multifunctional structure is a new concept enabling weight, and thus energy, to be saved in high-tech applications such as solar cars, solar planes or satellites. Composite sandwich structures with a weight of not, vert, similar800 g/m2 were developed, based on one 140 μm thick skin made of 0/90° carbon fiber-reinforced plastic (CFRP), one skin made ...

  7. Low-energy impact resistance of graphite-epoxy plates and ALS honeycomb sandwich panels

    Science.gov (United States)

    Hui, David

    1989-01-01

    Low energy impact may be potentially dangerous for many highly optimized stiff structures. Impact by foreign objects such as birds, ice, and runways stones or dropping of tools occur frequently and the resulting damage and stress concentrations may be unacceptable from a designer's standpoint. The barely visible, yet potentially dangerous dents due to impact of foreign objects on the Advanced Launch System (ALS) structure are studied. Of particular interest is the computation of the maximum peak impact force for a given impactor mass and initial velocity. The theoretical impact forces will be compared with the experimental dropweight results for the ALS face sheets alone as well as the ALS honeycomb sandwich panels.

  8. External mean flow influence on sound transmission through finite clamped double-wall sandwich panels

    Science.gov (United States)

    Liu, Yu; Catalan, Jean-Cédric

    2017-09-01

    This paper studies the influence of an external mean flow on the sound transmission through finite clamped double-wall sandwich panels lined with poroelastic materials. Biot's theory is employed to describe wave propagation in poroelastic materials and various configurations of coupling the poroelastic layer to the facing plates are considered. The clamped boundary of finite panels are dealt with by the modal superposition theory and the weighted residual (Garlekin) method, leading to a matrix equation solution for the sound transmission loss (STL) through the structure. The theoretical model is validated against existing theories of infinite sandwich panels with and without an external flow. The numerical results of a single incident wave show that the external mean flow has significant effects on the STL which are coupled with the clamped boundary effect dominating in the low-frequency range. The external mean flow also influences considerably the limiting incidence angle of the panel system and the effect of the incidence angle on the STL. However, the influences of the azimuthal angle and the external flow orientation are negligible.

  9. Flutter Characteristic Study of Composite Sandwich Panel with Functionally Graded Foam Core

    Directory of Open Access Journals (Sweden)

    Peng Jin

    2016-01-01

    Full Text Available This paper attempts to investigate the flutter characteristic of sandwich panel composed of laminated facesheets and a functionally graded foam core. The macroscopic properties of the foam core change continuously along this direction parallel to the facesheet lamina. The model used in the study is a simple sandwich panel-wing clamped at the root, with three simple types of grading strategies for FGM core: (1 linear grading strategy in the chord-wise direction, (2 linear grading strategy in the span-wise direction, and (3 bilinear grading of properties of foam core across the panel. The results show that use of FGM core has the potential to increase the flutter speed of the sandwich panel. Finally, a minimum weight design of composite sandwich panel with lamination parameters of facesheet and density distribution of foam core as design variables is conducted using particle swarm optimization (PSO.

  10. Sandwich Structure Based On Corrugated-Core: A Review

    Directory of Open Access Journals (Sweden)

    Zaid N. Z. M.

    2016-01-01

    Full Text Available Sandwich structures are commonly based on polymeric foam and honeycomb core material, for use in lightweight applications such as fuselage in aero plane, hull in marine construction and others. A review of sandwich structure based on corrugated-core is proposed and presented in this paper. Firstly, this paper aims to provide a means of comparing available sandwich structure in industries. Secondly, this paper aims to provide sandwich structure with corrugated-core for future research development efforts in field of sandwich construction. This paper starts with introduction of composite material such as sandwich structure, the advantages of sandwich structure was shown. After that these papers provide the structure of sandwich structure which includes the two faces and the cores. Furthermore, sandwich structure with different cores, which is honeycomb, foam core and corrugated core are discussed. At the end, the paper discussed more on corrugated-core for future research development.

  11. Blast Load Response of Steel Sandwich Panels with Liquid Encasement

    Energy Technology Data Exchange (ETDEWEB)

    Dale Karr; Marc Perlin; Benjamin Langhorst; Henry Chu

    2009-10-01

    We describe an experimental investigation of the response of hybrid blast panels for protection from explosive and impact forces. The fundamental notion is to dissipate, absorb, and redirect energy through plastic collapse, viscous dissipation, and inter-particle forces of liquid placed in sub-structural compartments. The panels are designed to absorb energy from an impact or air blast by elastic-plastic collapse of the panel substructure that includes fluid-filled cavities. The fluid contributes to blast effects mitigation by providing increased initial mass and resistance, by dissipation of energy through viscosity and fluid flow, and by redirecting the momentum that is imparted to the system from the impact and blast impulse pressures. Failure and deformation mechanisms of the panels are described.

  12. Lamb wave-based BVID imaging for a curved composite sandwich panel

    Science.gov (United States)

    He, Jiaze; Yuan, Fuh-Gwo

    2017-02-01

    Composite sandwich structures, consisting of a low density core sandwiched between two laminated facesheets, have been widely used in various aerospace structures. A new Lamb wave-based imaging condition, which will be referred to as the inverse incident wave energy (IIWE) imaging criterion, is proposed in this paper to resolve the situations where the incident wave energy weakly penetrates into the damaged area in the upper facesheet region. Current imaging conditions by analyzing wavefield reconstructed from laser Doppler vibrometer (LDV) scanning have been proven to be adequate for imaging damage in layered composite laminates. In this research, those current imaging conditions were applied and compared in the composite foam structures for barely visible impact damage (BVID). A piezoelectric wafer was used to excite Lamb waves into the structure and a LDV was used to scan the potential damaged areas in the upper facesheet of the panel. A BVID site in a curved composite sandwich foam aileron was inspected using various wavefield analysis methods and the damage images were compared with C-scan images. A few imaging conditions that are effective for this BVID site are identified when the incident waves have difficulties penetrating into the damaged region.

  13. Experimental Investigation of Dynamic Response and Deformation of Aluminium Honeycomb Sandwich Panels Subjected to Underwater Impulsive Loads

    Directory of Open Access Journals (Sweden)

    Da-Lin Xiang

    2015-01-01

    Full Text Available The response of aluminium sandwich panels with three thicknesses’ core subjected to different underwater loading levels has been studied in the fluid-structure interaction (FSI experiments. The transient response of the panels is measured using a three-dimensional (3D Digital Image Correlation (DIC system, along with high-speed photography. The full-field shape and displacement profiles of dry face sheets were recorded in real time compared with those of monolithic plate. The out-of-plane deflection and in-plane strain were quantified and analyzed. Three typical deformation modes of sandwich panel were identified. The results show that the core structure is crushed resulting in an initial large circular shape of deformation in the center area of panels. From this moment on, the panel is starting to act as a free vibration beam with initial velocities. The deformation modes consisted of homogeneous large deformation for both face sheets, obvious deformation border on wet face sheet, core node imprinting, remarkable wrinkled skin of deformation border, and a partial delamination and partial tear failure of the dry face. The blast-resistance of sandwich panel can be highly efficiently improved by increasing the thickness of core structure.

  14. Experimental and Theoretical Deflections of Hybrid Composite Sandwich Panel under Four-point Bending Load

    Directory of Open Access Journals (Sweden)

    Jauhar Fajrin

    2017-03-01

    Full Text Available This paper presents a comparison of theoretical and experimental deflection of a hybrid sandwich panel under four-point bending load. The paper initially presents few basic equations developed under three-point load, followed by development of model under four-point bending load and a comparative analysis between theoretical and experimental results. It was found that the proposed model for predicting the deflection of hybrid sandwich panels provided fair agreement with the experimental values. Most of the sandwich panels showed theoretical deflection values higher than the experimental values, which is desirable in the design. It was also noticed that the introduction of intermediate layer does not contribute much to reduce the deflection of sandwich panel as the main contributor for the total deflection was the shear deformation of the core that mostly determined by the geometric of the samples and the thickness of the core.

  15. Interfacial Crack Arrest in Sandwich Panels with Embedded Crack Stoppers Subjected to Fatigue Loading

    DEFF Research Database (Denmark)

    Martakos, G.; Andreasen, J. H.; Berggreen, Christian

    2017-01-01

    of the embedded crack arresters was evaluated in terms of the achieved enhancement of the damage tolerance of the tested sandwich panels. A finite element (FE) model of the experimental setup was used for predicting propagation rates and direction of the crack growth. The FE simulation was based on the adoption......A novel crack arresting device has been implemented in sandwich panels and tested using a special rig to apply out-of-plane loading on the sandwich panel face-sheets. Fatigue crack propagation was induced in the face-core interface of the sandwich panels which met the crack arrester. The effect...... of linear fracture mechanics and a fatigue propagation law (i.e. Paris law) to predict the residual fatigue life-time and behaviour of the test specimens. Finally, a comparison between the experimental results and the numerical simulations was made to validate the numerical predictions as well...

  16. Energy Dissipation in Sandwich Structures During Axial Compression

    DEFF Research Database (Denmark)

    Urban, Jesper

    2002-01-01

    The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full-scale structu......The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full...

  17. On the assumption of transverse isotropy of a honeycomb sandwich panel for NDT applications

    Science.gov (United States)

    Schaal, Christoph; Tai, Steffen; Mal, Ajit

    2017-04-01

    Due to their excellent strength-to-weight ratio, honeycomb sandwich panels are being increasingly used in lightweight structures, in particular in aircraft and aerospace industry. Delaminations of individual plies in the composite skins or disbonds of a layer in the multi-layer plate structures often remain undetected during visual inspection. Using guided ultrasonic waves, such hidden defects can be detected. For the successful application of ultrasonic nondestructive testing methods, however, wave propagation characteristics have to be well-understood. Recently developed semi-analytical techniques allow for the calculation of dispersion characteristics for many materials. However, the elastic material behavior is often simplified for these calculations. For example, woven composite laminates are modeled as a homogeneous, transversely isotropic plate. While these simplifications only lead to minor errors, the modeling of aluminum honeycomb core sandwich panels with homogeneous, transversely isotropic layers has yet to be validated. In this paper, an efficient numerical approach is used to determine the dispersion characteristics of a honeycomb core layer with and without simplified material behavior. A full 3D-model, including the honeycomb cells, of a small representative volume element of the material is generated using finite elements, and the resulting dispersion curves are compared to the ones obtained from simplified models. In addition to dispersion curves, the displacement fields of the waves are also analyzed.

  18. A Comparative Study of Ballistic Resistance of Sandwich Panels with Aluminum Foam and Auxetic Honeycomb Cores

    Directory of Open Access Journals (Sweden)

    Shu Yang

    2013-01-01

    Full Text Available An innovative auxetic-cored sandwich panel (AXP is proposed. Its perforation resistant performance under high-velocity projectile impact was numerically analyzed using the validated finite element simulation techniques and compared with that of the aluminum foam-cored sandwich panel (AFP of identical dimensions and weight. It has been found that the AXP is far superior to the AFP in ballistic resistance because of the material concentration at the impacted area due to the negative Poisson's ratio (NPR effect. A parametric study was carried out to investigate the effects of several key parameters, including impact velocity, face and core thicknesses, and core density, on the ballistic resistance of the AXP and AFP. The results show that the ballistic limit and perforation energy of the AXP is greatly affected by these parameters. Meanwhile, the advantages of AXP over AFP being used as ballistic resistant structures are highlighted. The primary outcome of this research is new information on the development and design of advanced ballistic resistant structures containing auxetic materials.

  19. Sound transmission analysis of MR fluid based-circular sandwich panels: Experimental and finite element analysis

    Science.gov (United States)

    Hemmatian, Masoud; Sedaghati, Ramin

    2017-11-01

    Magnetorheological Fluids (MR) have been recently utilized in sandwich panels to provide variable stiffness and damping to effectively control vibrations. In this study, the sound transmission behavior of MR based-sandwich panels is investigated through development of an efficient finite element model. A clamped circular sandwich panel with elastic face sheets and MR Fluid as the core layer has been considered. A finite element model utilizing circular and annular elements has been developed to derive the governing equations of motion in the finite element form. The transverse velocity is then calculated and utilized to obtain the sound radiated from the panel and subsequently the sound transmission loss. In order to validate the simulated results, a test setup including two anechoic spaces and an electro-magnet has been designed and fabricated. The magnetic flux density generated inside the electromagnet is simulated using magneto-static finite element analysis and validated with the measured magnetic flux density using Gaussmeter. The results from magneto-static analysis is used to derive an approximate polynomial function to evaluate the magnetic flux density as a function of the plate's radius and applied current. The STL and first axisymmetric natural frequency of the MR sandwich panels with aluminum face sheets are simulated and compared with those obtained experimentally. Finally, a parametric study on the effect of applied magnetic field, the thickness of the core layer and the thickness of face sheets on the STL and natural frequency of the adaptive sandwich panel are presented.

  20. Flexural behavior of sandwich panels with cellular wood, plywood stiffener/foam and thermoplastic composite core

    NARCIS (Netherlands)

    Labans, E.; Kalnins, Kaspars

    2017-01-01

    A series of experimental tests have been carried out on three types of novel sandwich panels mainly designed for application in lightweight mobile housing. Two types of the panels are manufactured entirely from wood-based materials while the third one presents a combination of plywood for surfaces

  1. Failure of uniformly compression loaded debond damaged sandwich panels — An experimental and numerical study

    DEFF Research Database (Denmark)

    Moslemian, Ramin; Quispitupa, Amilcar; Berggreen, Christian

    2012-01-01

    This paper deals with the failure of compression-loaded sandwich panels with an implanted circular face/core debond. Uniform compression tests were conducted on intact sandwich panels with three different types of core material (H130, H250 and PMI) and on similar panels with circular face....../core debonds having three different diameters. The strains and out-of-plane displacements of the panel surface were monitored using the digital image correlation technique. Mixed mode bending tests were conducted to determine the fracture toughness of the face/core interface of the panels. Finite element...... analysis and linear elastic fracture mechanics were employed to determine the critical buckling load and compression strength of the panels. Modeling approaches and failure criteria are discussed. Numerically determined crack propagation loads in most of the cases show a fair agreement with experimental...

  2. Behaviour of partially composite precast concrete sandwich panels under flexural and axial loads

    Science.gov (United States)

    Tomlinson, Douglas George

    Precast concrete sandwich panels are commonly used on building exteriors. They are typically composed of two concrete wythes that surround rigid insulation. They are advantageous as they provide both structural and thermal resistance. The structural response of sandwich panels is heavily influenced by shear connectors that link the wythes together. This thesis presents a study on partially composite non-prestressed precast concrete wall panels. Nine flexure tests were conducted on a wall design incorporating 'floating' concrete studs and Glass Fibre Reinforced Polymer (GFRP) connectors. The studs encapsulate and stiffen the connectors, reducing shear deformations. Ultimate loads increased from 58 to 80% that of a composite section as the connectors' reinforcement ratio increased from 2.6 to 9.8%. This design was optimized by reinforcing the studs and integrating them with the structural wythe; new connectors composed of angled steel or Basalt-FRP (BFRP) were used. The load-slip response of the new connector design was studied through 38 double shear push-through tests using various connector diameters and insertion angles. Larger connectors were stronger but more likely to pull out. Seven flexure tests were conducted on the new wall design reinforced with different combinations of steel and BFRP connectors and reinforcement. Composite action varied from 50 to 90% depending on connector and reinforcement material. Following this study, the axial-bending interaction curves were established for the new wall design using both BFRP and steel connectors and reinforcement. Eight panels were axially loaded to predesignated loads then loaded in flexure to failure. A technique is presented to experimentally determine the effective centroid of partially composite sections. Beyond the tension and compression-controlled failure regions of the interaction curve, a third region was observed in between, governed by connector failure. Theoretical models were developed for the bond

  3. Fatigue behavior of wood-fiber-based tri-axial engineered sandwich composite panels (ESCP)

    Science.gov (United States)

    Jinghao Li; John F. Hunt; Shaoqin Gong; Zhiyong Cai

    2015-01-01

    The static and fatigue bending behavior of wood-fiber-based tri-axial engineered sandwich composite panels (ESCP) has been investigated by four-point bending tests. Fatigue panels and weakened panels (wESCP) with an initial interface defect were manufactured for the fatigue tests. Stress σ vs. number of cycles curves (S-N) were recorded under the different stress...

  4. Dynamic Failure of Composite and Sandwich Structures

    CERN Document Server

    Abrate, Serge; Rajapakse, Yapa D S

    2013-01-01

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

  5. Finite Element Analysis of the SciFi-Nomex-Sandwich Panels

    CERN Document Server

    Schultz von Dratzig, Arndt

    2015-01-01

    A finite element analysis of the SciFi-Nomex-sandwich panels has been carried out in order to investigate their thermo-mechanical properties. This does not include the cooling of the silicon photomultipliers but is restricted to the panels themselves. Two kinds of panels have been considered: panels with 40 mm thickness and panels with 50 mm thickness. Both versions are equipped with mats of six layers of scintillating fibers. The analyses were carried out for a series of mechanical and thermal loads which might occur during the production or installation of the detector. For both versions the stiffnesses prove to be sufficient and no critical stresses or strains are found.

  6. Development and evaluation of aerogel-filled BMI sandwich panels for thermal barrier applications

    Directory of Open Access Journals (Sweden)

    A. Dineshkumar

    2016-07-01

    Full Text Available This study details a fabrication methodology envisaged to manufacture Glass/BMI honeycomb core aerogel-filled sandwich panels. Silica aerogel granules are used as core fillers to provide thermal insulation properties with little weight increase. Experimental heat transfer studies are conducted on these panels to study the temperature distribution between their two surfaces. Numerical studies are also carried out to validate the results. Despite exhibiting good thermal shielding capabilities, the Glass/BMI sandwich panels are found to oxidise at 180 ºC if exposed directly to heat. In order to increase the temperature bearing capacity and the operating temperature range for these panels, a way of coating them from outside with high temperature spray paint was tried. With a silicone-based coating, the temperature sustainability of these sandwich panels is found to increase to 350 ºC. This proved the effectiveness of the formed manufacturing process, selected high temperature coating, the coating method as well as the envisaged sandwich panel concept.

  7. Features of fire and explosion safety of buildings from a sandwich of panels

    Directory of Open Access Journals (Sweden)

    Salymova Eugenia

    2017-01-01

    Full Text Available Recently in Russia about 100% of buildings of an oil and gas complex are built with use triplex a sandwich of panels (S.P. Almost all these buildings are explosive and increase in their exploisure-resistance requires application of easily thrown off or safety designs. A sandwich of the panel is an ideal applicant for a role of safety designs according to the weight characteristics. Except inertial properties extremely important characteristic is opening pressure. This size remains acritical in view of a variety of their sizes, thickness of metal sheets, a variety of their fastening to metal designs. In work opening pressure at explosion for a sandwich of panels of 2×1,2 m in size for various options of fastening is experimentally received. We suspect that load of one knot of fastening does not depend on the panel sizes, only on the knot device. For various ways of fastening design pressure of opening in case of a normal distribution of durability of clusters is defined. The criterion for assessment of effectiveness of the panels used as safety designs is received. This criterion determines the maximal pressure upon dive during opening. The received criterion confirms effectiveness a sandwich of panels as a safety design.

  8. Ultrasonic guided wave characterization and damage detection in foam-core sandwich panel using PWAS and LDV

    Science.gov (United States)

    Chakraborty, Nibir; Roy Mahapatra, D.; Srinivasan, Gopalakrishnan

    2012-04-01

    Lamb wave type guided wave propagation in foam core sandwich structures and detectability of damages using spectral analysis method are reported in this paper. An experimental study supported by theoretical evaluation of the guided wave characteristics is presented here that shows the applicability of Lamb wave type guided ultrasonic wave for detection of damage in foam core sandwich structures. Sandwich beam specimens were fabricated with 10 mm thick foam core and 0.3 mm thick aluminum face sheets. Thin piezoelectric patch actuators and sensors are used to excite and sense guided wave. Group velocity dispersion curves and frequency response of sensed signal are obtained experimentally. The nature of damping present in the sandwich panel is monitored by measuring the sensor signal amplitude at various different distances measured from the center of the linear phased array. Delaminations of increasing width are created and detected experimentally by pitch-catch interrogation with guided waves and wavelet transform of the sensed signal. Signal amplitudes are analyzed for various different sizes of damages to differentiate the damage size/severity. A sandwich panel is also fabricated with a planer dimension of 600 mm x 400 mm. Release film delamination is introduced during fabrication. Non-contact Laser Doppler Vibrometer (LDV) is used to scan the panel while exciting with a surface bonded piezoelectric actuator. Presence of damage is confirmed by the reflected wave fringe pattern obtained from the LDV scan. With this approach it is possible to locate and monitor the damages by tracking the wave packets scattered from the damages.

  9. Degradation of shear stiffness of Nomex honeycomb sandwich panel in laser irradiation

    Science.gov (United States)

    Wang, Jiawei; Jiang, Houman; Wu, Lixiong; Zhu, Yongxiang; Wei, Chenghua; Ma, Zhiliang; Wang, Lijun

    2017-05-01

    Based on the overhanging beam three-point bending method, the experimental system was set up to measure the variety of shear stiffness of Nomex honeycomb sandwich panel in laser irradiation. The shear stiffness of the specimens under different laser power density was measured. The result shows that the thermal effect during the laser irradiation leads to the degradation of mechanical properties of Nomex honeycomb sandwich panel. High temperature rise rate in the specimen is another main reason for the shear stiffness degeneration. This research provides a reference for the degradation of mechanical properties of composite materials in laser irradiation and proposes a new method for the study of laser interaction with matter.

  10. Cost optimization of load carrying thin-walled precast high performance concrete sandwich panels

    DEFF Research Database (Denmark)

    Hodicky, Kamil; Hansen, Sanne; Hulin, Thomas

    2015-01-01

    The paper describes a procedure to find the structurally and thermally efficient design of load-carrying thin-walled precast High Performance Concrete Sandwich Panels (HPCSP) with an optimal economical solution. A systematic optimization approach is based on the selection of material’s performances...... and HPCSP’s geometrical parameters as well as on material cost function in the HPCSP design. Cost functions are presented for High Performance Concrete (HPC), insulation layer, reinforcement and include labour-related costs. The present study reports the economic data corresponding to specific manufacturing....... The solution of the optimization problem is performed in the computer package software Matlab® with SQPlab package and integrates the processes of HPCSP design, quantity take-off and cost estimation. The proposed optimization process outcomes in complex HPCSP design proposals to achieve minimum cost of HPCSP....

  11. Fracture Behaviours in Compression-loaded Triangular Corrugated Core Sandwich Panels

    Directory of Open Access Journals (Sweden)

    Zaid N.Z.M.

    2016-01-01

    Full Text Available The failure modes occurring in sandwich panels based on the corrugations of aluminium alloy, carbon fibre-reinforced plastic (CFRP and glass fibre-reinforced plastic (GFRP are analysed in this work. The fracture behaviour of these sandwich panels under compressive stresses is determined through a series of uniform lateral compression performed on samples with different cell wall thicknesses. Compression test on the corrugated-core sandwich panels were conducted using an Instron series 4505 testing machine. The post-failure examinations of the corrugated-core in different cell wall thickness were conducted using optical microscope. Load-displacement graphs of aluminium alloy, GFRP and CFRP specimens were plotted to show progressive damage development with five unit cells. Four modes of failure were described in the results: buckling, hinges, delamination and debonding. Each of these failure modes may dominate under different cell wall thickness or loading condition, and they may act in combination. The results indicate that thicker composites corrugated-core panels tend can recover more stress and retain more stiffness. This analysis provides a valuable insight into the mechanical behaviour of corrugated-core sandwich panels for use in lightweight engineering applications.

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

    Science.gov (United States)

    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.

  13. Harmonic Differential Quadrature Analysis of Soft-Core Sandwich Panels under Locally Distributed Loads

    Directory of Open Access Journals (Sweden)

    Xinwei Wang

    2016-11-01

    Full Text Available Sandwich structures are widely used in practice and thus various engineering theories adopting simplifying assumptions are available. However, most engineering theories of beams, plates and shells cannot recover all stresses accurately through their constitutive equations. Therefore, the soft-core is directly modeled by two-dimensional (2D elasticity theory without any pre-assumption on the displacement field. The top and bottom faces act like the elastic supports on the top and bottom edges of the core. The differential equations of the 2D core are then solved by the harmonic differential quadrature method (HDQM. To circumvent the difficulties in dealing with the locally distributed load by point discrete methods such as the HDQM, a general and rigorous way is proposed to treat the locally distributed load. Detailed formulations are provided. The static behavior of sandwich panels under different locally distributed loads is investigated. For verification, results are compared with data obtained by ABAQUS with very fine meshes. A high degree of accuracy on both displacement and stress has been observed.

  14. On the Effect of Curvature in Debonded Sandwich Panels Subjected to Compressive Loading

    DEFF Research Database (Denmark)

    Moslemian, Ramin; Berggreen, Christian; Branner, Kim

    2008-01-01

    with a circular debond. The Crack Surface Displacement Extrapolation (CSDE) method is used to calculate fracture parameters in the interface. Compression tests were carried out on two types of debonded curved panels with different curvature using Digital Image Correlation (DIC) measurements to determine the full......The aim of this study is to obtain an understanding of the effect of panel curvature on residual compressive strength in debond damaged sandwich panels. Finite element analysis and linear elastic fracture mechanics are employed to analyze the residual compressive strength of curved panels...

  15. REKAYASA BAHAN KOMPOSIT SANDWICH HIBRID UNTUK STRUKTUR SISTEM PANEL

    Directory of Open Access Journals (Sweden)

    Agus Hariyanto

    2017-04-01

    Full Text Available Tujuan penelitian ini adalah menyelidiki pengaruh ketebalan core terhadap peningkatan kekuatan bending komposit sandwich hibrid berpenguat kombinasi serat rami woven dan serat gelas woven bermatrix polyester dengan core berpenguat kombinasi serbuk kayu jati dan mahoni bermatrix polyester. Mekanisme perpatahan diamati dengan foto makro. Bahan yang digunakan untuk skin adalah serat rami (woven, serat E-Glass (woven, resin unsaturated polyester 157 BQTN (UPRs. Bahan yang digunakan untuk core adalah serbuk kayu jati dan mahoni dengan mesh 30 pada fraksi volume 50%, resin unsaturated polyester 157 BQTN. Hardener yang digunakan adalah MEKPO dengan konsentrasi 1%. Komposit dibuat dengan metode cetak tekan. Komposit  sandwich  hibrid tersusun  terdiri  dari dua skin komposit hibrid dengan core hibrid di tengahnya. Skin komposit hibrid sebagai lamina terdiri  dari dua lamina serat gelas anyam dan satu lamina serat rami (woven - woven – woven. Fraksi volume serat komposit skin hibrid adalah 30%. Komposit core hibrid yang digunakan adalah serbuk kayu jati dan mahoni dengan mesh 30 pada fraksi volume 50% dengan resin unsaturated polyester 157 BQTN. Variabel utama penelitian yaitu tebal core (10, 20, 30, 40, dan 50 mm. Spesimen dan prosedur pengujian bending mengacu pada standard ASTM C 393. Hasil penelitian menunjukkan bahwa penambahan ketebalan core mampu meningkatkan momen bending. Namun, menurunkan kekuatan bending, facing bending dan tegangan geser core komposit sandwich hibrid. Mekanisme patahan diawali oleh kegagalan komposit skin bagian tarik, core gagal geser, dan diakhiri oleh kegagalan skin sisi tekan. Pada bagian daerah batas core dan komposit skin menunjukkan adanya kegagalan delaminasi.

  16. Compression strength of sandwich panels with sub-interface damage in the foam core

    NARCIS (Netherlands)

    Koysin, V.; Shipsha, Andrey; Skvortsov, Vitaly

    2009-01-01

    This paper addresses the effect of a local quasi-static indentation or a low-velocity impact on the residual strength of foam core sandwich panels subjected to edgewise compression. The damage is characterized by a local zone of crushed core accompanied by a residual dent in the face sheet.

  17. Optimal Design of Multistage Two-Dimensional Cellular-Cored Sandwich Panel Heat Exchanger

    Directory of Open Access Journals (Sweden)

    Yongcun Zhang

    2014-08-01

    Full Text Available For a two-dimensional (2D cellular-cored sandwich panel heat exchanger, there exists an optimum cell size to achieve the maximum heat transfer with the prescribed pressure drop when the length is fixed and the two plates are isothermal. However, in engineering design, it is difficult to find 2D cellular materials with the ideal cell size because the cell size selected must be from those commercially available, which are discrete, not continuous. In order to obtain the maximum heat dissipation, an innovative design scheme is proposed for the sandwich panel heat exchanger which is divided into multiple stages in the direction of fluid flow where the 2D cellular material in each stage has a specific cell size. An analytical model is presented to evaluate the thermal performance of the multistage sandwich panel heat exchanger when all 2D cellular materials have the same porosity. Also, a new parameter named equivalent cell size (ECS is defined, which is dependent on the cell size and length of cellular material in all stages. Results show that the maximum heat dissipation design of the multistage sandwich panel heat exchanger can be converted to make the ECS equal to the optimal cell size of the single-stage exchanger.

  18. Composite Sandwich Structures for Shock Mitigation and Energy Absorption

    Science.gov (United States)

    2016-06-28

    Michelle S. Hoo Fatt Department of Mechanical Engineering College of Engineering Akron, Ohio 44325-3903 Tel: 330-972-6308 Defense Technical...examined. In the second or continuation grant period (July 2014 to Apri I 20 16), the research was extended to address the behavior of composite sandwich...panel theory is based mostly on linear elastic response. This research extended composite sandwich theory by considering the facesheets as anisotropic

  19. Modal Strain Energy-Based Debonding Assessment of Sandwich Panels Using a Linear Approximation with Maximum Entropy

    Directory of Open Access Journals (Sweden)

    Viviana Meruane

    2017-11-01

    Full Text Available Sandwich structures are very attractive due to their high strength at a minimum weight, and, therefore, there has been a rapid increase in their applications. Nevertheless, these structures may present imperfect bonding or debonding between the skins and core as a result of manufacturing defects or impact loads, degrading their mechanical properties. To improve both the safety and functionality of these systems, structural damage assessment methodologies can be implemented. This article presents a damage assessment algorithm to localize and quantify debonds in sandwich panels. The proposed algorithm uses damage indices derived from the modal strain energy method and a linear approximation with a maximum entropy algorithm. Full-field vibration measurements of the panels were acquired using a high-speed 3D digital image correlation (DIC system. Since the number of damage indices per panel is too large to be used directly in a regression algorithm, reprocessing of the data using principal component analysis (PCA and kernel PCA has been performed. The results demonstrate that the proposed methodology accurately identifies debonding in composite panels.

  20. Impact Response of Aluminum Foam Sandwiches for Light-Weight Ship Structures

    Directory of Open Access Journals (Sweden)

    Eugenio Guglielmino

    2011-12-01

    Full Text Available The structures realized using sandwich technologies combine low weight with high energy absorbing capacity, so they are suitable for applications in the transport industry (automotive, aerospace, shipbuilding industry where the “lightweight design” philosophy and the safety of vehicles are very important aspects. While sandwich structures with polymeric foams have been applied for many years, currently there is a considerable and growing interest in the use of sandwiches with aluminum foam core. The aim of this paper was the analysis of low-velocity impact response of AFS (aluminum foam sandwiches panels and the investigation of their collapse modes. Low velocity impact tests were carried out by a drop test machine and a theoretical approach, based on the energy balance model, has been applied to investigate their impact behavior. The failure mode and the internal damage of the impacted AFS have also been investigated by a Computed Tomography (CT system.

  1. REKAYASA DAN MANUFAKTUR KOMPOSIT SANDWICH HIBRID UNTUK PANEL

    Directory of Open Access Journals (Sweden)

    Agus Hariyanto

    2017-10-01

    Full Text Available Tujuan  penelitian  ini  adalah  menyelidiki  pengaruh  fraksi  volume  core  terhadap peningkatan kekuatan Impak komposit sandwich hibrid berpenguat kombinasi serat rami  woven  dan  serat  gelas  woven  bermatrix  polyester  dengan  core  berpenguat kombinasi serbuk kayu jati dan mahoni bermatrix polyester. Mekanisme perpatahan diamati dengan foto makro.Bahan yang digunakan untuk skin adalah serat rami (woven, serat E-Glass (woven, resin  unsaturated  polyester  157  BQTN  (UPRs.  Bahan  yang  digunakan  untuk  core adalah serbuk kayu jati dan mahoni dengan mesh 30 pada fraksi volume 30%, 40%, dan 50%, resin unsaturated polyester 157 BQTN. Hardener yang digunakan adalah MEKPO  dengan  konsentrasi  1%.  Komposit  dibuat  dengan  metode  cetak  tekan. Komposit  sandwich  hibrid tersusun  terdiri  dari dua skin komposit hibrid dengan core hibrid ditengahnya. Skin komposit hibrid sebagai lamina terdiri  dari dua lamina serat gelas anyam dan satu lamina serat rami (woven - woven – woven. Fraksi volume serat komposit skin hibrid adalah 30%. Komposit core hibrid yang digunakan adalah serbuk kayu jati dan mahoni dengan mesh 30 pada fraksi volume 30%, 40%, dan 50% dengan resin unsaturated polyester 157 BQTN. Variabel utama penelitian yaitu fraksi volume core (30%, 40%, dan 50%. Spesimen dan prosedur pengujian Impak mengacu pada standard ASTM D 5942. Hasil  penelitian  menunjukkan  bahwa  penambahan  fraksi  volume  core  mampu meningkatkan energi serap dan kekuatan impak komposit sandwich hibrid. Mekanisme patahan  diawali  oleh  kegagalan  komposit  skin  bagian  tarik,  core  gagal  geser,  dan diakhiri oleh kegagalan skin sisi tekan. Pada bagian daerah batas core dan komposit skin menunjukkan adanya kegagalan delaminasi.

  2. Investigations on the influences of elastic foundations on the aerothermoelastic flutter and thermal buckling properties of lattice sandwich panels in supersonic airflow

    Science.gov (United States)

    Chai, Yu-Yang; Song, Zhi-Guang; Li, Feng-Ming

    2017-11-01

    The lattice sandwich panels supported on elastic mediums are often applied in the construction of aerospace structures because of the low specific weight, excellent bending rigidity and outstanding vibration properties. This elastic medium can be any spring materials including damping tapes or heat shields which are attached to one side of the sandwich panel. Therefore, in this paper, aerothermoelastic flutter and thermal buckling characteristics of sandwich panels with the pyramidal lattice core resting on elastic foundations in supersonic airflow are studied. The influences of geometrical parameters and elastic foundation on the panel flutter and thermal buckling of the structures are analyzed in detail. In the structural modeling, the first-order shear deformation theory is applied, and the effective material properties of the lattice core are used. The aerodynamic pressure is evaluated by the supersonic piston theory. Hamilton's principle and the assumed modes method are applied to formulate the equation of motion. The highlight point of this investigation is that an effective thermal buckling suppression method utilizing the elastic foundation is proposed, based on which the thermal buckling of the structure can be completely eliminated with the natural frequencies remaining unchanged when the shearing layer parameter is equal to the thermal load. Through the numerical results, the influences of the elastic foundation, aspect ratio, core-to-facesheet thickness ratio, and inclination angle of the core truss on the aerothermoelastic behaviors of the lattice sandwich panel are analyzed, and the thermal buckling elimination effects are also examined.

  3. Effect of Faces Type and Thickness on Mechanical Properties of Sandwich Panels

    Directory of Open Access Journals (Sweden)

    Mohammad Jabbari

    2014-05-01

    Full Text Available Sandwich panels are new kind of layered composites that usually are composed of three layers and their core layers thickness is higher but the top layers are determinative indetermination of the products strength and stiffness. In this study, effect of faces type and thickness on mechanical properties of sandwich panels was investigated. The variables included, faces type with 3, 4 and 5 mm thickness (beech face, popular face and adhesive type (PMDI. After making panels, sampling test (based on DIN- EN 326-1 was considered. Mechanical properties of panels included modulus of elasticity as well as module of rupture (based on DIN- EN 310 standard and impact bending strength (IBS (based on ASTM- D 3499 standard were measured. The gathered data were analyzed as completely randomized factorial design. The results showed that, the thickness of faces has a significant effect on the mechanical properties. With increasing thickness of 3 to 5 mm, modulus of rupture, modulus of elasticity and impact bending strength (IBS increased. The interaction effect between species and thickness showed that using of beech genus with 5 mm thickness leads to increase of mechanical properties in sandwich panels.

  4. Out-plane Compressive Properties for Isosceles Trapezoid Honeycomb Core of FRP Sandwich Panel

    Directory of Open Access Journals (Sweden)

    ZHENG Ji-liang

    2017-02-01

    Full Text Available The experiment and simulation investigations on out-plane compressive characteristics of FRP sandwich panel were conducted. The results show that two deformation stages are elastic deformation and fracture stages in out-plane compressive deformation. The yielding mode deformation as t1/h which is very big,while the buckling mode deformation as t1/h which is very small. The part 2 in the honeycomb core is main bearing part for sandwich panel,and the part 2 is supported by the part 1 and part 3 in the honeycomb core,while the honeycomb core is supported by the panel. So,the cell wall thickness of part 2 has the most significant influence on the compressive strength,and the influence by the cell wall side length of honeycomb core is the secondary,while the influence by the cell wall thickness of part 1 and part 3 in honeycomb core and the thickness of panel is the weakest. When the honeycomb core height is fixed,the compressive strength of FRP sandwich panel gradually increases along with honeycomb core layers increase.

  5. Fluxless Brazing and Heat Treatment of a Plate-Fin Sandwich Actively Cooled Panel

    Science.gov (United States)

    Beuyukian, C. S.

    1978-01-01

    The processes and techniques used to fabricate plate-fin sandwich actively cooled panels are presented. The materials were 6061 aluminum alloy and brazing sheet having clad brazing alloy. The panels consisted of small scale specimens, fatigue specimens, and a large 0.61 m by 1.22 m test panel. All panels were fluxless brazed in retorts in heated platen presses while exerting external pressure to assure intimate contact of details. Distortion and damage normally associated with that heat treatment were minimized by heat treating without fixtures and solution quenching in an organic polymer solution. The test panel is the largest fluxless brazed and heat treated panel of its configuration known to exist.

  6. Non-Uniform Compressive Strength of Debonded Sandwich Panels

    DEFF Research Database (Denmark)

    Nøkkentved, Alexandros; Lundsgaard-Larsen, Christian; Berggreen, Carl Christian

    2005-01-01

    debonds show a considerable strength reduction with increasing debond diameter, with failure mechanisms varying between fast debond propagation and wrinkling-introduced face compression failure for large and small debonds, respectively. Residual strength predictions are based on intact panel testing......, and a comparison between a simple numerical model and the experimental results shows fair agreement....

  7. Ultimate Failure of Debond Damaged Sandwich Panels Loaded with Lateral Pressure

    DEFF Research Database (Denmark)

    Jolma, Perttu; Segercrantz, Sebastian; Berggreen, Christian

    2007-01-01

    In this study a tool for assessing residual strength of debond damaged laterally loaded sandwich panels is developed. The analysis tool consists of a parametric finite element model and a fracture mechanics calculation procedure to determine the residual strength. The parametric approach allows...... with a number of different ship type panels. Debond criticality is evaluated by using the developed tool and by comparing the test results from panel experiments. The comparison shows that the analysis tool predicts both failure load and failure mode well. The tool can be used to determine the residual strength...

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

    Science.gov (United States)

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

    2013-01-01

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

  9. Sandwich panels with high performance concrete thin plates at elevated temperatures

    DEFF Research Database (Denmark)

    Hulin, Thomas; Hodicky, Kamil; Schmidt, Jacob Wittrup

    2015-01-01

    Performance of conventional load-carrying sandwich structures made of concrete can be improved by the use of high performance concrete (HPC) plates of thin sections (30 mm), linked by shear connectors ensuring the composite behaviour of the structure. This paper proposes the application...... concerned HMT modelling and elastic stress analysis with nonlinear temperature effects of a full size loaded sandwich wall, qualitatively assessing the location of critically stressed zones. Modelling output was compared to published experimental results. The model reproduced experimental temperature...

  10. Numerical Analysis of Dynamic Response of Corrugated Core Sandwich Panels Subjected to Near-Field Air Blast Loading

    Directory of Open Access Journals (Sweden)

    Pan Zhang

    2014-01-01

    Full Text Available Three-dimensional fully coupled simulation is conducted to analyze the dynamic response of sandwich panels comprising equal thicknesses face sheets sandwiching a corrugated core when subjected to localized impulse created by the detonation of cylindrical explosive. A large number of computational cases have been calculated to comprehensively investigate the performance of sandwich panels under near-field air blast loading. Results show that the deformation/failure modes of panels depend strongly on stand-off distance. The beneficial FSI effect can be enhanced by decreasing the thickness of front face sheet. The core configuration has a negligible influence on the peak reflected pressure, but it has an effect on the deflection of a panel. It is found that the benefits of a sandwich panel over an equivalent weight solid plate to withstand near-field air blast loading are more evident at lower stand-off distance.

  11. Investigation on vibration excitation of debonded sandwich structures using time-average digital holography.

    Science.gov (United States)

    Thomas, Binu P; Annamala Pillai, S; Narayanamurthy, C S

    2017-05-01

    Sandwich structures, in the modern aerospace industry, are more sought after due to their high strength to stiffness ratio resulting in significant weight gains. Optical techniques like time-average holography and shearography are preferred in industries for inspection of huge sandwich and composite panels because of whole-field (full coverage) inspection in a lesser time leading to large savings in cost. These techniques conventionally use sinusoidal frequency sweep to capture the local resonance of defective regions. This paper highlights the difficulties with the conventional approach of time-average digital holography (TADH) and proposes a novel defect identification strategy through square wave excitation. The proposed method enhances the speed and accuracy of inspection; thereby it saves cost and increases confidence level. Extensive experiments have been carried out using honeycomb sandwich panels to demonstrate the methodology.

  12. The Influence of Face Sheet Wrinkle Defects on the Performance of FRP Sandwich Structures

    DEFF Research Database (Denmark)

    Hayman, Brian; Berggreen, Carl Christian; Pettersson, Robert

    2005-01-01

    reported here, the influence of wrinkle defects on the in-plane compressive strength of quasiisotropic CFRP laminates used in PVC foam-cored sandwich panels has been investigated by three approaches: testing of sandwich beam specimens in fourpoint bending, testing of sandwich panels with in...

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

    Science.gov (United States)

    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. Finite Element Simulation and Assessment of Single-Degree-of-Freedom Prediction Methodology for Insulated Concrete Sandwich Panels Subjected to Blast Loads

    Science.gov (United States)

    2011-02-01

    sandwich panels for blast loads. blast load; finite element modeling; large deflection behavior; load-deflection response; precast concrete ; prestressed ...of Precast/ Prestressed Concrete Structures for Blast ...............................................6 3. MODEL DEVELOPMENT AND VALIDATION...Laboratory (AFRL) and a Daniel P. Jenny Research Fellowship Grant from the Precast/ Prestressed Concrete Institute (PCI). The current technical points of

  15. Study of the cracking of sandwich panels of plasterboard and rockwool

    Directory of Open Access Journals (Sweden)

    Alonso, J. A.

    2013-09-01

    Full Text Available This paper presents the study of plasterboard and rockwool sandwich panels cracking under flexural loading. These panels are usually used to perform interior partition walls and they frequently show cracking pathology due to excessive deflexion of the slabs. There are currently no reliable simulation models and experimental data for the study of this problem. This paper presents the results of an experimental campaign aimed to characterize the fracture behaviour of sandwich panels and their individual components. In addition, the paper presents a cohesive model with embedded crack to simulate the fracture behaviour of the panel. Finally we present the results of tests for mixed mode fracture (tensile / shear commercial panels and their behaviour is reproduced with the cohesive model proposed, yielding a good fit.Este artículo presenta el estudio de la rotura de paneles sándwich de yeso laminado y lana de roca bajo solicitaciones de flexo-tracción dentro de su plano. Estos paneles se emplean para conformar tabiques interiores de edificación y con frecuencia se fisuran por flechas excesivas en los forjados. Actualmente no hay modelos de cálculo fiables ni datos experimentales que permitan estudiar este problema. Este trabajo presenta los resultados de una campaña experimental encaminada a caracterizar el comportamiento en rotura de los paneles sándwich y de sus componentes individuales. Además, se presenta un modelo cohesivo con fisura embebida que permite simular el comportamiento en rotura del panel sándwich conjunto. Por último se presentan los resultados de los ensayos de fractura en modo mixto (tracción/cortante de paneles comerciales y se reproduce su comportamiento con el modelo cohesivo propuesto, obteniéndose un buen ajuste.

  16. Experimental and analytical study about the compressive behavior of eps sandwich panels

    Directory of Open Access Journals (Sweden)

    Carbonari, G.

    2013-09-01

    Full Text Available This study presents a detailed characterization of the behavior of EPS sandwich panels subject to normal load taking into account several variables. For that, two experimental programs were performed, leading to the proposal of an analytical formulation to estimate the maximum load resisted. The results obtained show how the height of the panel, the material properties, the position and configuration of the reinforcement may affect the resistance of panels. Special attention should be given to the eccentric position of the reinforcement, which may reduce considerably the maximum load resisted. Some recommendations about the optimum placement of the reinforcement are proposed.El presente estudio se centra en la caracterización del comportamiento de paneles tipo Sandwich con hormigón y EPS sometidos a cargas normales de compresión y teniendo en cuenta diferentes variables. Para ello, se han realizado campañas experimentales, cuyos resultados muestran que los aspectos geométricos, las propiedades de los materiales, la posición y la configuración del refuerzo influyen de manera significativa en la resistencia de los paneles. Asimismo se propone una formulación analítica para estimar la máxima carga resistida por los mismos. El estudio muestra que es especialmente importante definir la posición de las armaduras en la sección transversal ya que la excentricidad de las mismas reduce la resistencia a compresión de los paneles.

  17. Out-of-plane shear strength of steel-concrete sandwich panels

    OpenAIRE

    Sagaseta, Juan; Francis, Philip

    2017-01-01

    Steel-concrete-steel (SCS) sandwich panels consist of two steel plates connected with tie bars filled with concrete; composite action is achieved using headed studs in the plates. This form of composite construction has recently regained interest in the construction industry as it allows modular construction and decongestion of reinforcement which is particularly useful in large infrastructure such as tunnels, wind turbines and nuclear energy facilities. This paper investigates...

  18. Process Factors and Edgewise Compressive Properties of Scarf-repaired Honeycomb Sandwich Structures

    Science.gov (United States)

    Liu, Sui; Guan, Zhidong; Guo, Xia; Sun, Kai; Kong, Jiaoyue; Yan, Dongxiu

    2014-10-01

    Bonded repairs were conducted on flat and edge-closed composite sandwich panels that had undergone different levels of initial damage, and edgewise compression behaviors of repaired panel were tested. Experimental results indicate that these repair techniques can restore the compression performance of damaged panels effectively. The repaired specimens recovered an average of over 83 % of their strength. A k-sample Anderson-Darling test was used to analyze the influence of various parameters, including curing temperature, curing pressure, and repair configurations. After a thorough comparison, it was concluded that a high-temperature, high-pressure treatment can improve the mechanical performance of repaired panels, but the improvement is closely related to the structural complexity of the repaired region. A double-side repair scheme could be used to prevent the degradation of mechanical performance caused by the additional bending moment. The conclusions drawn in the present study provide further insight into the mechanical performance of repaired sandwich panels under edgewise compressive loads. These data facilitate the improved design methodology on bonded repair of composite sandwich structures.

  19. Enhanced Performance of Sandwich Structures by Improved Damage Tolerance

    DEFF Research Database (Denmark)

    Martakos, Georgios

    up to about 200,000 load cycles, and to assess the effect of high cycle fatigue damage propagation was simulated up to about 2,000,000 load cycles. It was demonstrated that the developed computational methodology is capable of modelling the fatigue behaviour of sandwich structures with embedded peel...... behaviour around the new crack stopper elements. In support for the experimental investigations, a Finite Element (FE) analysis based methodology, including fracture mechanics analysis and the so-called ‘cycle jump’ technique, was developed to predict the progression of damage in sandwich specimens...... with embedded crack stoppers. The starting point for the research was is a new design for a crack stopper, referred to as a ‘peel stopper’, which is proposed for foam cored sandwich structures. Initially, the ability of the peel stopper to prolong the fatigue life of sandwich structures has been demonstrated...

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

    Science.gov (United States)

    Ratcliffe, James G.; Jackson, Wade C.

    2008-01-01

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

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

    Science.gov (United States)

    Ratcliffe, James G.; Jackson, Wade C.

    2008-01-01

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

  2. Thermo-Fluidic Comparison between Sandwich Panels with Tetrahedral Lattice Cores Fabricated by Casting and Metal Sheet Folding

    Directory of Open Access Journals (Sweden)

    Xiaoqing Zhang

    2017-07-01

    Full Text Available This numerical study compares single-phase forced convective heat transfer between two sandwich panels with tetrahedral metallic lattice cores separately fabricated by investment casting and the more cost-effective metal sheet folding method. The numerical model is validated against available experimental data. For a given Reynolds number and core porosity, the results reveal that the brazed sandwich outperforms the casted sandwich, exhibiting a 13% to 16% higher Nusselt number. Bigger vertexes and more evident blockage of mainstream by the ligaments are found to intensify the horseshoe vortex and the counter-rotating vortex pair upstream and downstream of each vertex. Relative to the casted sandwich panel, therefore, endwall heat transfer is enhanced by 22% to 27%, while similar heat transfer is achieved on the ligaments. It is also found that, for a given Reynolds number, the brazed sandwich induces a 1.6 to 1.7 times higher pressure drop relative to the casted sandwich due to more severe flow separation caused by the sharp edges of the rectangular ligaments. Finally, for a given pumping power, both sandwiches provide a similar heat transfer performance. Given that the brazed sandwich is more cost-effective and easier to fabricate than the casted one, the former may be superior from an engineering application point of view.

  3. Experimental and Theoretical Study of Sandwich Panels with Steel Facesheets and GFRP Core

    Directory of Open Access Journals (Sweden)

    Hai Fang

    2016-01-01

    Full Text Available This study presented a new form of composite sandwich panels, with steel plates as facesheets and bonded glass fiber-reinforced polymer (GFRP pultruded hollow square tubes as core. In this novel panel, GFRP and steel were optimally combined to obtain high bending stiffness, strength, and good ductility. Four-point bending test was implemented to analyze the distribution of the stress, strain, mid-span deflection, and the ultimate failure mode. A section transformation method was used to evaluate the stress and the mid-span deflection of the sandwich panels. The theoretical values, experimental results, and FEM simulation values are compared and appeared to be in good agreement. The influence of thickness of steel facesheet on mid-span deflection and stress was simulated. The results showed that the mid-span deflection and stress decreased and the decent speed was getting smaller as the thickness of steel facesheet increases. A most effective thickness of steel facesheet was advised.

  4. Effects of debonds and face sheet damage in GRP sandwich panels in naval ships

    DEFF Research Database (Denmark)

    Hayman, B.; Berggreen, Christian; Quispitupa, Amilcar

    2009-01-01

    Sandwich construction with face sheets of fibre-reinforced plastics (FRP) and a core of polymer foam or balsa wood offer a lightweight construction that is well suited to naval and other vessels for high-speed operation or where payload considerations require that the structural weight be minimised......-core debonds and face sheet impact damage is being extended to cover sandwich lay-ups with non-crimp glass reinforcements, vinylester matrix materials and foam cores of both PVC and PMI. Cases with both compressive and (for face sheet impact damage) tensile loading are considered. Modelling approaches...

  5. Constitutive Modeling of the Facesheet to Core Interface in Honeycomb Sandwich Panels Subject to Mode I Delamination

    Science.gov (United States)

    Hoewer, Daniel; Lerch, Bradley A.; Bednarcyk, Brett A.; Pineda, Evan Jorge; Reese, Stefanie; Simon, Jaan-Willem

    2017-01-01

    A new cohesive zone traction-separation law, which includes the effects of fiber bridging, has been developed, implemented with a finite element (FE) model, and applied to simulate the delamination between the facesheet and core of a composite honeycomb sandwich panel. The proposed traction-separation law includes a standard initial cohesive component, which accounts for the initial interfacial stiffness and energy release rate, along with a new component to account for the fiber bridging contribution to the delamination process. Single cantilever beam tests on aluminum honeycomb sandwich panels with carbon fiber reinforced polymer facesheets were used to characterize and evaluate the new formulation and its finite element implementation. These tests, designed to evaluate the mode I toughness of the facesheet to core interface, exhibited significant fiber bridging and large crack process zones, giving rise to a concave downward concave upward pre-peak shape in the load-displacement curve. Unlike standard cohesive formulations, the proposed formulation captures this observed shape, and its results have been shown to be in excellent quantitative agreement with experimental load-displacement and apparent critical energy release rate results, representative of a payload fairing structure, as well as local strain fields measured with digital image correlation.

  6. The Application of Statistical Design of Experiments to Study the In-Plane Shear Behaviour of Hybrid Composite Sandwich Panel

    Directory of Open Access Journals (Sweden)

    Fajrin J.

    2016-03-01

    Full Text Available This paper presents a statistical aspect of experimental study on the in-plane shear behaviour of hybrid composite sandwich panel with intermediate layer. The study was aimed at providing information of how significant the contribution of intermediate layer to the in-plane shear behaviour of new developed sandwich panel. The investigation was designed as a single factor experimental design and the results were throughly analysed with statistics software; Minitab 15. The panels were tested by applying a tensile force along the diagonal of the test frame simulating pure shear using a 100 kN MTS servo-hydraulic UTM. The result shows that the incorporation of intermediate layer has sinificantly enhanced the in-plane shear behaviour of hybrid composite sandwich panel. The statistical analysis shows that the value of F0 is much higher than the value of Ftable, which has a meaning that the improvement provided by the incorporation of intermediate layer is statistically significant.

  7. Experimental Validation of the Transverse Shear Behavior of a Nomex Core for Sandwich Panels

    Science.gov (United States)

    Farooqi, M. I.; Nasir, M. A.; Ali, H. M.; Ali, Y.

    2017-05-01

    This work deals with determination of the transverse shear moduli of a Nomex® honeycomb core of sandwich panels. Their out-of-plane shear characteristics depend on the transverse shear moduli of the honeycomb core. These moduli were determined experimentally, numerically, and analytically. Numerical simulations were performed by using a unit cell model and three analytical approaches. Analytical calculations showed that two of the approaches provided reasonable predictions for the transverse shear modulus as compared with experimental results. However, the approach based upon the classical lamination theory showed large deviations from experimental data. Numerical simulations also showed a trend similar to that resulting from the analytical models.

  8. Thermal-mechanical behavior of sandwich panels with closed-cell foam core under intensive laser irradiation

    Directory of Open Access Journals (Sweden)

    Li Zhi-Qiang

    2014-01-01

    Full Text Available Temperature field and thermal deformation of sandwich panels with closed-cell aluminum alloy foam core and heat-protective layer, which are subjected to Gaussian laser beam intensively irradiating, are investigated numerically. In transient heat analysis models, the influence of thermal conductivity, specific heat, and thickness of heat-protective layer on the temperature rise of the sandwich panels is calculated. In stress analysis models, a sequence coupled numerical method is utilized to simulate the thermal stress and deformation of sandwich panels induced by thermal expansion. Simulation results indicate that the temperature at center of sandwich panel increases firstly and then drops gradually with the increase of thermal conductivity of heat-protective layer after laser irradiation, and the critical thermal conductivity is obtained, while it decreases with the increase of specific heat and thickness of heat-protective layer. The thermal stress verifies the “Cyclo-hoop effect”, i. e. radial stress is compression stress in “hot zone” and tension stress in “cold zone”. The max thermal deformation of sandwich panels slightly increases with the increase of thickness of heat-protective layer for given specific heat and thermal conductivity.

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

    Science.gov (United States)

    Giancaspro, James William

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

  10. Nanocrystalline Aluminum Truss Cores for Lightweight Sandwich Structures

    Science.gov (United States)

    Schaedler, Tobias A.; Chan, Lisa J.; Clough, Eric C.; Stilke, Morgan A.; Hundley, Jacob M.; Masur, Lawrence J.

    2017-08-01

    Substitution of conventional honeycomb composite sandwich structures with lighter alternatives has the potential to reduce the mass of future vehicles. Here we demonstrate nanocrystalline aluminum-manganese truss cores that achieve 2-4 times higher strength than aluminum alloy 5056 honeycombs of the same density. The scalable fabrication approach starts with additive manufacturing of polymer templates, followed by electrodeposition of nanocrystalline Al-Mn alloy, removal of the polymer, and facesheet integration. This facilitates curved and net-shaped sandwich structures, as well as co-curing of the facesheets, which eliminates the need for extra adhesive. The nanocrystalline Al-Mn alloy thin-film material exhibits high strength and ductility and can be converted into a three-dimensional hollow truss structure with this approach. Ultra-lightweight sandwich structures are of interest for a range of applications in aerospace, such as fairings, wings, and flaps, as well as for the automotive and sports industries.

  11. Optimal Fuzzy and Dynamics Design of Ecological Sandwich Panel Vessel Roofs

    Directory of Open Access Journals (Sweden)

    Heikki Martikka

    2011-01-01

    Full Text Available In this study the basic engineering principles, goals, and constraints are all combined with fuzzy methodology and applied to optimally design sandwich panel circular plate roofs for large vessels loaded statically and dynamically. These panels are made up of two stiff, strong veneer skins separated by vertical and peripheral stiffener plates. Advantages are high strength, lightweight, and sustainability. In the present approach, first the goals and constraints of the end user are identified and expressed as decision variables which are formulated using the engineering variables for materials, geometry, and function. Then same consistent fuzzy satisfaction functions are formed over the desired ranges to suit the customer's desires. The risk of extreme dynamic loadings exciting resonance is studied by natural frequency and mode analysis by FEM and analytical models. The results show the most critical locations and give guidelines for innovative remedies of the concept before detailed FEM analyses to finalize the design.

  12. Mechanical properties and optical testing of metal honeycomb sandwich panel in MTPS

    Science.gov (United States)

    Lu, Jie; Zou, Guang ping; Liang, Jun

    2008-11-01

    Mechanical tests of a Co-based superalloy honeycomb thermal protection system (TPS) panel are finished at room temperature. The lateral tensile limit strength is higher than 59MPa and nearly four multiples of the flatwise compressive strength. Also the modulus in lateral tests are nearly two multiples of the ones under compressive loads. Because of many advantages in application, two optical non-contact methods are introduced in this work to solve different problems of honeycomb sandwich panels. Longitudinal strain of lateral tensile specimens is obtained by digital speckle correlation method (DSCM) and the results of different sub-pixel methods are constrasted. Then the equivalent elastic modulus is calculated further. Electronic speckle shearography pattern interferometry (ESSPI) is presented to obtain the nondestructive results of debonding defects between honeycomb cores and face sheets. Also the size and approximate location are decided real-time. All the results show the two introduced methods are feasible.

  13. Improvement Noise Insulation Performance of Polycarbonate Pane using Sandwich Structure

    Science.gov (United States)

    Shen, Min; Nagamura, Kazuteru; Nakagawa, Noritoshi; Okamura, Masaharu

    Polycarbonate (PC) laminates offer the possibility of designing strong and light weight panes application in automobile. However, the noise insulation performance of PC pane is worse than glass pane because of its high rate of stiffness to low weight. In this work, a new ultra-thin(less than 10mm) sandwich pane is proposed to obtain high transmission loss(TL). The sandwich structure consists of two thin laminates plates of the same PC material and a thin lightweight damping core bonded between those plates. Then TL is predicted using decoupled equations representing symmetric and anti-symmetric motions for a sandwich PC pane. The effects of various structural and material parameters on noise insulation performance are investigated with numerical examples. Numerical results show that the shear rigidity has evident effect on coincidence frequency and proposed structure has better noise insulation properties than single layer PC pane of equivalent thickness.

  14. Non-linear Dynamic Analysis of Steel Hollow I-core Sandwich Panel under Air Blast Loading

    Directory of Open Access Journals (Sweden)

    Asghar Vatani Oskouei

    2015-12-01

    Full Text Available In this paper, the non-linear dynamic response of novel steel sandwich panel with hollow I-core subjected to blast loading was studied. Special emphasis is placed on the evaluation of midpoint displacements and energy dissipation of the models. Several parameters such as boundary conditions, strain rate, mesh dependency and asymmetrical loading are considered in this study. The material and geometric non-linearities are also considered in the numerical simulation. The results obtained are compared with available experimental data to verify the developed FE model. Modeling techniques are described in detail. According to the results, sandwich panels with hollow I-core allowed more plastic deformation and energy dissipation and less midpoint displacement than conventional I-core sandwich panels and also equivalent solid plate with the same weight and material.

  15. Identification of material properties of sandwich structure with piezoelectric patches

    Directory of Open Access Journals (Sweden)

    Zemčík R.

    2008-11-01

    Full Text Available The work focuses on light-weight sandwich structures made of carbon-epoxy skins and foam core which have unique bending stiffness compared to conventional materials. The skins are manufactured by vacuum autoclave technology from unidirectional prepregs and the sandwich is then glued together. The resulting material properties of the structure usually differ from those provided by manufacturer or even those obtained from experimental tests on separate materials, which makes computational models unreliable. Therefore, the properties are identified using the combination of experimental analysis of the sandwich with attached piezoelectric transducer and corresponding static and modal finite element analyses. Simple mathematical optimization with repetitive finite element solution is used. The model is then verified by transient analysis when the piezoelectric patch is excited by harmonic signals covering the first two eigen-frequencies and the induced oscillations are measured by laser sensor.

  16. Flexural Behavior of Aluminum Honeycomb Core Sandwich Structure

    Science.gov (United States)

    Matta, Vidyasagar; Kumar, J. Suresh; Venkataraviteja, Duddu; Reddy, Guggulla Bharath Kumar

    2017-05-01

    This project is concerned with the fabrication and flexural testing of aluminium honey comb sandwich structure which is a special case of composite materials that is fabricated by attaching two thin but stiff skins to a light weight but thick core. The core material is normally low density material but its high thickness provide the sandwich composite with high bonding stiffness. Honeycomb core are classified into two types based on the materials and structures. Hexagonal shape has a unique properties i.e has more bonding strength and less formation time based on the cell size and sheet thickness. Sandwich structure exhibit different properties such as high load bearing capacity at low weight and has excellent thermal insulation. By considering the above properties it has tendency to minimize the structural problem. So honey comb sandwich structure is choosed. The core structure has a different applications such as aircraft, ship interiors, construction industries. As there is no proper research on strength characteristics of sandwich structure. So, we use light weight material to desire the strength. There are different parameters involved in this structure i.e cell size, sheet thickness and core height. In this project we considered 3 level of comparison among the 3 different parameters cell size of 4, 6 and 8 mm, sheet thickness of 0.3, 0.5 and 0.7 mm, and core height of 20,25 and 30 mm. In order to reduce the number of experiment we use taguchi design of experiment, and we select the L8 orthogonal array is the best array for this type of situation, which clearly identifies the parameters by independent of material weight to support this we add the minitab software, to identify the main effective plots and regression equation which involves the individual response and corresponding parameters. Aluminium material is used for the fabrication of Honeycomb sandwich structure among the various grades of aluminium we consider the AL6061 which is light weight material

  17. Multi-objective optimization of a functionally graded sandwich panel under mechanical loading in the presence of stress constraint

    Science.gov (United States)

    Ashjari, Mohammad; Khoshravan, Mohammad Reza

    2017-12-01

    A method was presented for multi-objective optimization of material distribution of simply supported functionally graded (FG) sandwich panel, and sensitivity analyses of optimal designs were also conducted based on design variables and objective functions. The material composition was assumed to vary only in the thickness direction. Piecewise cubic interpolation of volume fractions was used to calculate volume fractions of constituent material phases at a point; these fractions were defined at a limited number of evenly spaced control points. The effective material properties of the panel were obtained by applying the linear rule of mixtures. The behavior of FG sandwich panel was predicted by Reddy's assumptions of third-order shear deformation theory. Exact solutions for deflections and stresses of simply supported sandwich panel were presented using the Navier-type solution technique. The volume fractions at control points, material, and thickness of the faces which were selected as decision variables were optimized by a multi-objective evolutionary algorithm known as the fast and elitist multi-objective genetic algorithm (NSGA-II). The mass and deflection of the model were considered the objective functions to be minimized with stress constraints. This model was optimized to verify the capability and efficiency of the proposed model under mechanical loading. The framework proposed for designing FG sandwich panel under pure mechanical conditions was furnished by the results.

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

    Science.gov (United States)

    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.

  19. The Effect of Face and Adhesive Types on Mechanical Properties of Sandwich Panels Made from Honeycomb Paper

    Directory of Open Access Journals (Sweden)

    Mohsen Saffari

    2013-11-01

    Full Text Available Sandwich panels are new kind of layered composites that usually are composed of three layers and their core layer's thickness is higher and the outer layers are determinative in determination of the products strength and stiffness. The core layer is commonly made of honeycomb paper, corrugated paper and polyurethane etc. In this study, effects of face and adhesive types on mechanical properties of sandwich panels made from honeycomb paper were investigated. The variables included three types; beech face, poplar face and hardboard (S2S face, veneer less and adhesive type (two types; epoxy and PVA. Out of experimental panels specimens were cut and tested according to DIN E 326-1 standard. Mechanical properties of panels, included modulus of elasticity as well as modulus of rupture at the edge and surface (based on DIN EN 310 standard and Impact Bending Strength (IBS of the panels (based on ASTM D 3499 standard were measured. The gathered data were analyzed as completely randomized factorial design. Highest mechanical properties were reported for panels glued with epoxy resin and containing fiberboard at the middle. According to results, optimum condition of producing sandwich panels was observed in uses of epoxy resin and fiberboard S2S face, veneer less at the middle.

  20. Experimental and Numerical Investigation of the FRP Shear Mechanism for Concrete Sandwich Panels

    DEFF Research Database (Denmark)

    Hodicky, Kamil; Sopal, G.; Rizkalla, S.

    2015-01-01

    of this interface surface area. Test results also indicated that increasing the rigid foam thickness decreases the overall shear flow strength when compared with the same quantity of CFRP grid spacing. A nonlinear three-dimensional (3D) FEM analysis was performed to model the behavior of the tested segments......This paper investigates the composite action of 46 segments representing precast concrete sandwich panels (PCSPs) using a fiber-reinforced polymer [FRP; specifically, a carbon fiber-reinforced polymer (CFRP)] grid/rigid foam as a shear mechanism. The experimental aspect of the research reported...... reported in this paper indicated that increasing the spacing between vertical lines of CFRP grid increase the overall shear flow strengths due to the increase of the bonded contact area of the rigid foam to the concrete surface. However, the overall shear stresses were decreased due to the increase...

  1. Finite element analysis of hypervelocity impact behaviour of CFRP-Al/HC sandwich panel

    Directory of Open Access Journals (Sweden)

    Phadnis Vaibhav A.

    2015-01-01

    Full Text Available The mechanical response of CFRP-Al/HC (carbon fibre-reinforced/epoxy composite face sheets with Al honeycomb core sandwich panels to hyper-velocity impact (up to 1 km/s is studied using a finite-element model developed in ABAQUS/Explicit. The intraply damage of CFRP face sheets is analysed by mean of a user-defined material model (VUMAT employing a combination of Hashin and Puck criteria, delamination modelled using cohesive-zone elements. The damaged Al/HC core is assessed on the basis of a Johnson Cook dynamic failure model while its hydrodynamic response is captured using the Mie-Gruneisen equation of state. The results obtained with the developed finite-element model showed a reasonable correlation to experimental damage patterns. The surface peeling of both face sheets was evident, with a significant delamination around the impact location accompanied by crushing HC core.

  2. Experimental Study on the Performance of Polyurethane-Steel Sandwich Structure under Debris Flow

    National Research Council Canada - National Science Library

    Peizhen Li; Shutong Liu; Zheng Lu

    2017-01-01

    Polyurethane-steel sandwich structure, which creatively uses the polyurethane-steel sandwich composite as a structural material, is proposed to strengthen the impact resistance of buildings under debris flow...

  3. Experimental, Theoretical and Numerical Investigation of the Flexural Behaviour of the Composite Sandwich Panels with PVC Foam Core

    Science.gov (United States)

    Mostafa, A.; Shankar, K.; Morozov, E. V.

    2014-08-01

    This study presents the main results of an experimental, theoretical and numerical investigation on the flexural behaviour and failure mode of composite sandwich panels primarily developed for marine applications. The face sheets of the sandwich panels are made up of glass fibre reinforced polymer (GFRP), while polyvinylchloride (PVC) foam was used as core material. Four-point bending test was carried out to investigate the flexural behaviour of the sandwich panel under quasi static load. The finite element (FE) analysis taking into account the cohesive nature of the skin-core interaction as well as the geometry and materials nonlinearity was performed, while a classical beam theory was used to estimate the flexural response. Although the FE results accurately represented the initial and post yield flexural response, the theoretical one restricted to the initial response of the sandwich panel due to the linearity assumptions. Core shear failure associate with skin-core debonding close to the loading points was the dominant failure mode observed experimentally and validated numerically and theoretically.

  4. Development of biobased sandwich structures for mass transit application

    Science.gov (United States)

    Munusamy, Sethu Raaj

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

  5. Thermal-Mechanical Optimization of Folded Core Sandwich Panels for Thermal Protection Systems of Space Vehicles

    Directory of Open Access Journals (Sweden)

    Chen Zhou

    2017-01-01

    Full Text Available The integrated thermal protection system (ITPS is a complicated system that addresses both mechanical and thermal considerations. An M-pattern folded core sandwich panel packed with low-density insulation material provides inherently low mass for a potential ITPS panel. Herein, we identify the most influential geometric parameters and establish a viable, computationally efficient optimization procedure. Variables considered for optimization are geometric dimensions of the ITPS, while temperature and deflection are taken as constraints. A one-dimensional (1D thermal model based on a modified form of the rule of mixtures was established, while a three-dimensional (3D model was adopted for linear static analyses. Parametric models were generated to facilitate a design of experiment (DOE study, and approximate models using radial basis functions were obtained to carry out the optimization process. Sensitivity studies were first conducted to investigate the effect of geometric parameters on the ITPS responses. Then optimizations were performed for both thermal and thermal-mechanical constraints. The results show that the simplified 1D thermal model is able to predict temperature through the ITPS thickness satisfactorily. The combined optimization strategy evidently improves the computational efficiency of the design process showing it can be used for initial design of folded core ITPS.

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

    Science.gov (United States)

    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.

  7. Application of fibre reinforced plastic sandwich structures for automotive crashworthiness applications

    NARCIS (Netherlands)

    Lukaszewicz, D.; Blok, L.G.; Kratz, J.; Ward, C.; Kassapoglou, C.; Elmarakbi, A.; Araújo, A.L.

    2016-01-01

    In this work the application of fibre reinforced plastic (FRP) sandwich
    structures
    , with particular focus on aramid fibre tufted sandwiches is being studied for
    automotive crashworthiness applications using impact testing and numerical simulation.

  8. A Comparative Study of the Analysis, Numerical Modelling and Experimental Test on a Sandwich Panel with Plane and Profiled Facings

    Directory of Open Access Journals (Sweden)

    Raluca Hohan

    2010-01-01

    Full Text Available Sandwich panels are remarkable products because they can be as strong as a solid material but with less weight. The analysis that is required to predict the stresses and deflections in panels with flat or lightly profiled facings is that of conventional beam theory but with the addition of shear deformation. Knowing that the profiled sheets bring an increase of the flexural stiffness, formulas showing the calculus of a panel with flat and profiled facings are established. A comparison between the results of a mathematical calculus, an experimental test and a numerical modelling is provided.

  9. Experimental and simulation of split semi-torus key in PVC foam core to improve the debonding resistance of composite sandwich panel

    Science.gov (United States)

    Juliyana, M.; Santhana Krishnan, R.

    2018-02-01

    The sandwich composite panels consisting of facesheet and core material are used as a primary structural member for aerospace, civil and marine areas due to its high stiffness to weight ratio. But the debonding nature of facesheet from the foam core under shear loading conditions leads to failure of the composite structure. To inhibit the debonding, an innovative methodology of introducing semi-torus key is used in the present study. The polyvinyl chloride foam core(PVC) is grooved and filled with semi-torus shaped chopped strand prepregs which are sandwiched between alternate layers of woven roven(WR) and chopped strand mat(CSM) skins by vacuum infusion process. The sandwich panel manufactured with semi-torus keys is evaluated regarding experimental and numerical simulations under shear loading conditions. The present innovative concept delays the debonding between face-sheet and foam core with enhancement the shear load carrying capability as the initial stiffness is higher than the conventional model. Also, the shear behaviour of the proposed concept is in good agreement with experimental results. The split semi-torus keys sustain the shear failure resulting in resistance to debonding capability.

  10. The Effect of Face Sheet Wrinkle Defects on the Strength of FRP Sandwich Structures

    DEFF Research Database (Denmark)

    Hayman, Brian; Berggreen, Christian; Pettersson, Robert

    2007-01-01

    . In the studies reported here, the influence of wrinkle defects on the in-plane compressive strength of quasi-isotropic carbon fiber reinforced plastic (CFRP) laminates used in PVC foam-cored sandwich panels has been investigated by three approaches: testing of sandwich beam specimens in four-point bending...

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

    Directory of Open Access Journals (Sweden)

    S. Jedari Salami

    2013-01-01

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

  12. Sandwich-structured hollow fiber membranes for osmotic power generation

    KAUST Repository

    Fu, Feng Jiang

    2015-11-01

    In this work, a novel sandwich-structured hollow fiber membrane has been developed via a specially designed spinneret and optimized spinning conditions. With this specially designed spinneret, the outer layer, which is the most crucial part of the sandwich-structured membrane, is maintained the same as the traditional dual-layer membrane. The inner substrate layer is separated into two layers: (1) an ultra-thin middle layer comprising a high molecular weight polyvinylpyrrolidone (PVP) additive to enhance integration with the outer polybenzimidazole (PBI) selective layer, and (2) an inner-layer to provide strong mechanical strength for the membrane. Experimental results show that a high water permeability and good mechanical strength could be achieved without the expensive post treatment process to remove PVP which was necessary for the dual-layer pressure retarded osmosis (PRO) membranes. By optimizing the composition, the membrane shows a maximum power density of 6.23W/m2 at a hydraulic pressure of 22.0bar when 1M NaCl and 10mM NaCl are used as the draw and feed solutions, respectively. To our best knowledge, this is the best phase inversion hollow fiber membrane with an outer selective PBI layer for osmotic power generation. In addition, this is the first work that shows how to fabricate sandwich-structured hollow fiber membranes for various applications. © 2015 Elsevier B.V.

  13. Studi Eksperimen Balok Sandwich Glass Fiber Reinforcement Panel – Foam (GFRP-Foam pada Rumah Sederhana 2 Lantai

    Directory of Open Access Journals (Sweden)

    Dwi Mide Febriyan

    2017-01-01

    Full Text Available Gempa Sumatera Barat (2009 dan Mentawai (2010 telah menewaskan lebih dari 400 jiwa dan menyebabkan sedikitnya 88.000 kerusakan berat pada bangunan-bangunan yang ada. Diketahui bahwa kerusakan tersebut diakibatkan oleh beberapa faktor, salah satunya adalah akibat dari berat struktur bangunan yang konvensional. Preliminary desain menggunakan metode grafis dari H. G. Allen cukup akurat untuk mendapatkan dimensi panel komposit balok sandwich GFRP-Foam dengan beban rencana yang ditentukan. Program bantu elemen hingga menghasilkan analisa tegangan yang terjadi pada model panel balok sandwich. Beberapa pengujian terhadap model dari panel balok sandwich mengguakan FPB telah dilakukan untuk mendapatkan perilaku mekanis balok terhadap beban gravitasi. Pengujian menunjukkan bahwa balok berperilaku elastis hingga beban 500 kg dan keruntuhan terjadi ketiak beban mencapai 800 kg.. Hasil pengujian tersebut mengarah pada kesimpulan bahwa panel balok dengan 4 lapis fiberglass combo mat untuk masing – masing skin dan dengan dimensi balok 140 mm x 240 mm dengan bentang 3 meter memadai untuk menahan beban rencana dari rumah sederhana 2 lantai

  14. Delamination during drilling in polyurethane foam composite sandwich structures

    Science.gov (United States)

    Sharma, S. C.; Krishna, M.; Narasimha Murthy, H. N.

    2006-06-01

    The objective of this paper is to study the influence of drilling velocity, feed rate, and flank length on the delamination of polyurethane foam sandwich structures. A Taguchi-based design of experiments was used to assess the importance of the drilling parameters, and scanning electron microscopy (SEM) was used to assess the damage from drilling. The drilling of sandwich structures results in significant damage caused by delamination and surface roughness around the drilled holes. The drilling process was evaluated based on a factor called the delamination factor, which is defined as the ratio of the maximum diameter of the damage zone, measured using SEM, to the standard hole diameter (drill diameter). Analysis of variance of the experimental results showed that cutting speed was the most significant parameter among the controllable parameters during drilling of sandwich specimens followed by flank length and feed rate. Finally, confirmation tests were performed to make a comparison between the experimental results and the correlation results. The damage mechanisms are explained using SEM.

  15. Experimental and theoretical studies into the stress-strain state of the purlin supported by sandwich panels

    Directory of Open Access Journals (Sweden)

    Danilov Aleksandr Ivanovich

    2014-12-01

    Full Text Available In the article, the co-authors analyze the findings of the experimental and theoretical studies into the real behaviour of a thin-walled cold-formed purlin as part of the roof structure made of sandwich panels. The roof structure fragment was tested; displacements and stresses, that the purlin was exposed to, were identified in respect of each loading increment. NASTRAN software was employed to perform the numerical analysis of the roof structure, pre-exposed to experimental tests, in the geometrically and physically non-linear setting. The finite element model, generated as a result (the numerical analysis pattern, is sufficiently well-set, given the proposed grid of elements, and it ensures reasonably trustworthy results. The diagrams describing the stress/displacement to the load ratio and obtained numerically are consistent with those generated experimentally. The gap between the critical loading values reaches 4%. Analytical and experimental findings demonstrate their close conformity, and this fact may justify the application of the numerical model, generated within the framework of this research project, in the course of any further research actions. The co-authors have identified that the exhaustion of the bearing capacity occurs due to the loss of the buckling resistance as a result of the lateral torsional buckling.

  16. Composite Behavior of Insulated Concrete Sandwich Wall Panels Subjected to Wind Pressure and Suction

    Directory of Open Access Journals (Sweden)

    Insub Choi

    2015-03-01

    Full Text Available A full-scale experimental test was conducted to analyze the composite behavior of insulated concrete sandwich wall panels (ICSWPs subjected to wind pressure and suction. The experimental program was composed of three groups of ICSWP specimens, each with a different type of insulation and number of glass-fiber-reinforced polymer (GFRP shear grids. The degree of composite action of each specimen was analyzed according to the load direction, type of the insulation, and number of GFRP shear grids by comparing the theoretical and experimental values. The failure modes of the ICSWPs were compared to investigate the effect of bonds according to the load direction and type of insulation. Bonds based on insulation absorptiveness were effective to result in the composite behavior of ICSWP under positive loading tests only, while bonds based on insulation surface roughness were effective under both positive and negative loading tests. Therefore, the composite behavior based on surface roughness can be applied to the calculation of the design strength of ICSWPs with continuous GFRP shear connectors.

  17. Composite Behavior of Insulated Concrete Sandwich Wall Panels Subjected to Wind Pressure and Suction.

    Science.gov (United States)

    Choi, Insub; Kim, JunHee; Kim, Ho-Ryong

    2015-03-19

    A full-scale experimental test was conducted to analyze the composite behavior of insulated concrete sandwich wall panels (ICSWPs) subjected to wind pressure and suction. The experimental program was composed of three groups of ICSWP specimens, each with a different type of insulation and number of glass-fiber-reinforced polymer (GFRP) shear grids. The degree of composite action of each specimen was analyzed according to the load direction, type of the insulation, and number of GFRP shear grids by comparing the theoretical and experimental values. The failure modes of the ICSWPs were compared to investigate the effect of bonds according to the load direction and type of insulation. Bonds based on insulation absorptiveness were effective to result in the composite behavior of ICSWP under positive loading tests only, while bonds based on insulation surface roughness were effective under both positive and negative loading tests. Therefore, the composite behavior based on surface roughness can be applied to the calculation of the design strength of ICSWPs with continuous GFRP shear connectors.

  18. Carbon footprint hotspots of prefabricated sandwich panels for hostel construction in Perlis

    Science.gov (United States)

    Razali, Norashikin; Ayob, Afizah; Chandra, Muhammad Erwan Shah; Zaki, Mohd Faiz Mohammad; Ahmad, Abdul Ghapar

    2017-10-01

    Sustainable design and construction have gained increasing research interest, and reduction of carbon from building construction has become the main focus of environmental strategies in Malaysia. This study uses life cycle assessment and life cycle inventory analysis frameworks to estimate the amount of carbon footprint expressed in carbon dioxide equivalent tons (CO2e) produced by manufacturing prefabricated Industrialized Building System sandwich panels and its installation for a five-story hostel in Perlis, Malaysia. Results show that the carbon footprint hotspots were centered on boiler machine operation and cement with 4.52 and 369.04 tons CO2e, respectively. This finding is due to the extensive energy used for steam heating and high engine rating for the boiler. However, for cement, the carbon footprint hotspots are caused by the large quantity of cement applied in shotcrete mixture and its high extraction and production CO2 emission values. The overall onsite materials generated 96.36% of the total carbon footprint. These carbon footprint hotspot results constitute a necessary base for the Malaysian government in accomplishing an adequate dimensioning of carbon emissions in the building sector.

  19. Standard practice for radiologic examination of flat panel composites and sandwich core materials used in aerospace applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This practice is intended to be used as a supplement to Practices E 1742, E 1255, and E 2033. 1.2 This practice describes procedures for radiologic examination of flat panel composites and sandwich core materials made entirely or in part from fiber-reinforced polymer matrix composites. Radiologic examination is: a) radiographic (RT) with film, b) Computed Radiography (CR) with Imaging Plate, c) Digital Radiology (DR) with Digital Detector Array’s (DDA), and d) Radioscopic (RTR) Real Time Radiology with a detection system such as an Image Intensifier. The composite materials under consideration typically contain continuous high modulus fibers (> 20 GPa), such as those listed in 1.4. 1.3 This practice describes established radiological examination methods that are currently used by industry that have demonstrated utility in quality assurance of flat panel composites and sandwich core materials during product process design and optimization, process control, after manufacture inspection, in service exami...

  20. Study on the performance of infrared thermal imaging light source for detection of impact defects in CFRP composite sandwich panels

    Energy Technology Data Exchange (ETDEWEB)

    Park, Hee Sang [R and D, Korea Research Institute of Smart Material and Structures System Association, Daejeon (Korea, Republic of); Choi, Man Yong; Kwon, Koo Ahn; Park, Jeong Hak; Choi, Won Jae [Safety measurement center, Korea research Institute of Standards and Science, Daejeon (Korea, Republic of); Jung, Hyun Chul [Dept. of Mechanical Engineering Chosun University, Gwangju (Korea, Republic of)

    2017-04-15

    Recently, composite materials have been mainly used in the main wings, ailerons, and fuselages of aircraft and rotor blades of helicopters. Composite materials used in rapid moving structures are subject to impact by hail, lightning, and bird strike. Such an impact can destroy fiber tissues in the composite materials as well as deform the composite materials, resulting in various problems such as weakened rigidity of the composite structure and penetration of water into tiny cracks. In this study, experiments were conducted using a 2 kW halogen lamp which is most frequently used as a light source, a 2 kW near-infrared lamp, which is used for heating to a high temperature, and a 6 kW xenon flash lamp which emits a large amount of energy for a moment. CFRP composite sandwich panels using Nomex honeycomb core were used as the specimens. Experiments were carried out under impact damages of 1, 4 and 8 J. It was found that the detection of defects was fast when the xenon flash lamp was used. The detection of damaged regions was excellent when the halogen lamp was used. Furthermore, the near-infrared lamp is an effective technology for showing the surface of a test object.

  1. Random Vibration Suppression of a Truss Core Sandwich Panel Using Independent Modal Resonant Shunt and Modal Criterion

    Directory of Open Access Journals (Sweden)

    Kongming Guo

    2017-05-01

    Full Text Available The aim of this paper is to suppress the random spatial vibration of the face sheet of a lightly damped truss core sandwich panel structure. Because broad-bandwidth vibration energy is concentrated in resonance peaks for lightly damped structures, an independent modal resonant shunt control method is utilized to add damping ratios to the chosen modes. In this method, each piezoelectric transducer is connected to a single resonant shunt which is tuned to control the vibration of a single mode. An H2 norm sensitivity-based modal criterion is proposed in order to determine which modes to control under a given bandwidth of excitation and input-output condition. Numerical simulation is implemented while control strategies with different controlled modes are compared. The result shows that the independent modal resonant shunt control method can suppress random vibration response of the face sheet by using only a few piezoelectric transducers, and the proposed modal criterion can be used to determine which modes to control.

  2. Vibro-acoustic topology optimization of sandwich panels partially treated with MR fluid and silicone rubber core layer

    Science.gov (United States)

    Hemmatian, Masoud; Sedaghati, Ramin

    2017-12-01

    This study aims to investigate the topology optimization of sandwich panels partially treated with magnetorheological (MR) fluid and silicone rubber core layer. The finite element (FE) model of the partially treated sandwich panel has been developed using circular and 4-node quadrilateral elements. The FE model is then utilized to solve the free and forced vibration equations of motion to obtain the natural frequencies, loss factors and sound transmission loss (STL), respectively. Systematic parametric studies on the effect of the position of the MR fluid and silicone rubber on the first axisymmetric natural frequency, the corresponding loss factor and also the STL are presented. It has been shown that the vibrational and acoustical behavior of the sandwich panel changes considerably as the location of the MR treatment changes. To conduct optimization problems efficiently without using the full FE model, linear meta-models have been derived using random and D-optimal design points. The developed meta-models are then utilized to solve the topology optimization problems using the genetic algorithm and integer programing methods. The suitability of the identified optimal candidates are further evaluated using the developed FE model to determine the optimized topology for the constraint and unconstraint problems.

  3. Modelling the behaviour of composite sandwich structures when subject to air-blast loading

    Directory of Open Access Journals (Sweden)

    H Arora

    2016-09-01

    Full Text Available Large-scale glass fibre reinforced polymer (GFRP and carbon fibre reinforced polymer (CFRP sandwich structures (1.6 m x 1.3 m were subject to explosive air blast (100 kg TNT equivalent at stand-off distances of 14 m. Digital image correlation (DIC was used to obtain full-field data for the rear-face of each deforming target. A steel plate of comparable mass per unit area was also subjected to the same blast conditions for comparison. The experimental data was then verified with finite element models generated in Abaqus/Explicit. Close agreement was obtained between the numerical and experimental results, confirming that the CFRP panels had a superior blast performance to the GFRP panels. Moreover all composite targets sustained localised failures (that were more severe in the GFRP targets but retained their original shape post blast. The rear-skins remained intact for each composite target with core shear failure present.

  4. Effect of Rigid Polyurethane Foam Core Density on Flexural and Compressive Properties of Sandwich Panels with Glass/Epoxy Faces

    Directory of Open Access Journals (Sweden)

    saeed Nemati

    2013-01-01

    Full Text Available Sandwich panels as composite materials have two external walls of either metallic or polymer type. The space between these walls is filled by hard foam or other materials and the thickness of different layers is based on the final application of the panel. In the present work, the extent of variation in core density of polyether urethane foam and subsequent flexural and compressive changes in sandwich panels with glass or epoxy face sheets are tested and investigated. A number of hard polyether urethane foams with different middle panel layers density 80-295 kg/m3 are designed to study the effect of foam density on mechanical properties including flexural and compressive properties. Flexural and compressive test resultsshow that increased core density leads to improved mechanical properties. The slope of the curve decreases beyond density of 235 kg/m3. The reason may be explained on the limitation of shear intensity in increasing the mechanical properties. In this respect an optimum density of 235 kg/m3 is obtained for the system under examinations and for reaching higher strength panels, foams of different core materials should be selected.

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

    Science.gov (United States)

    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.

  6. Composite Behavior of a Novel Insulated Concrete Sandwich Wall Panel Reinforced with GFRP Shear Grids: Effects of Insulation Types

    Directory of Open Access Journals (Sweden)

    JunHee Kim

    2015-03-01

    Full Text Available A full-scale experimental program was used in this study to investigate the structural behavior of novel insulated concrete sandwich wall panels (SWPs reinforced with grid-type glass-fiber-reinforced polymer (GFRP shear connectors. Two kinds of insulation-expanded polystyrene (EPS and extruded polystyrene (XPS with 100 mm thickness were incased between the two concrete wythes to meet the increasing demand for the insulation performance of building envelope. One to four GFRP shear grids were used to examine the degree of composite action of the two concrete wythes. Ten specimens of SWPs were tested under displacement control subjected to four-point concentrated loads. The test results showed that the SWPs reinforced with GFRP grids as shear connectors developed a high degree of composite action resulting in high flexural strength. The specimens with EPS foam exhibited an enhanced load-displacement behavior compared with the specimens with XPS because of the relatively stronger bond between insulation and concrete. In addition, the ultimate strength of the test results was compared to the analytical prediction with the mechanical properties of only GRFP grids. The specimens with EPS insulation presented higher strength-based composite action than the ones with XPS insulation.

  7. Composite Behavior of a Novel Insulated Concrete Sandwich Wall Panel Reinforced with GFRP Shear Grids: Effects of Insulation Types.

    Science.gov (United States)

    Kim, JunHee; You, Young-Chan

    2015-03-03

    A full-scale experimental program was used in this study to investigate the structural behavior of novel insulated concrete sandwich wall panels (SWPs) reinforced with grid-type glass-fiber-reinforced polymer (GFRP) shear connectors. Two kinds of insulation-expanded polystyrene (EPS) and extruded polystyrene (XPS) with 100 mm thickness were incased between the two concrete wythes to meet the increasing demand for the insulation performance of building envelope. One to four GFRP shear grids were used to examine the degree of composite action of the two concrete wythes. Ten specimens of SWPs were tested under displacement control subjected to four-point concentrated loads. The test results showed that the SWPs reinforced with GFRP grids as shear connectors developed a high degree of composite action resulting in high flexural strength. The specimens with EPS foam exhibited an enhanced load-displacement behavior compared with the specimens with XPS because of the relatively stronger bond between insulation and concrete. In addition, the ultimate strength of the test results was compared to the analytical prediction with the mechanical properties of only GRFP grids. The specimens with EPS insulation presented higher strength-based composite action than the ones with XPS insulation.

  8. Fluid Structure Interaction Effect on Sandwich Composite Structures

    Science.gov (United States)

    2011-09-01

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

  9. Improvement of the in-plane crushing response of CFRP sandwich panels by through-thickness reinforcements

    NARCIS (Netherlands)

    Blok, L.G.; Kratz, J.; Lukaszewicz, D.; Hesse, S; Ward, C.; Kassapoglou, C.

    2016-01-01

    Fibre reinforced plastic (FRP) composite materials can provide superior specific energy absorption performance over conventional metallic structures if crush stability can be maintained during the impact event. The core in sandwich structures helps to stabilise the crush front by preventing global

  10. A study on an efficient prediction of welding deformation for T-joint laser welding of sandwich panel PART I : Proposal of a heat source model

    Directory of Open Access Journals (Sweden)

    Jae Woong Kim

    2013-09-01

    Full Text Available The use of I-Core sandwich panel has increased in cruise ship deck structure since it can provide similar bending strength with conventional stiffened plate while keeping lighter weight and lower web height. However, due to its thin plate thickness, i.e. about 4~6 mm at most, it is assembled by high power CO2 laser welding to minimize the welding deformation. This research proposes a volumetric heat source model for T-joint of the I-Core sandwich panel and a method to use shell element model for a thermal elasto-plastic analysis to predict welding deformation. This paper, Part I, focuses on the heat source model. A circular cone type heat source model is newly suggested in heat transfer analysis to realize similar melting zone with that observed in experiment. An additional suggestion is made to consider negative defocus, which is commonly applied in T-joint laser welding since it can provide deeper penetration than zero defocus. The proposed heat source is also verified through 3D thermal elasto-plastic analysis to compare welding deformation with experimental results. A parametric study for different welding speeds, defocus values, and welding powers is performed to investigate the effect on the melting zone and welding deformation. In Part II, focuses on the proposed method to employ shell element model to predict welding deformation in thermal elasto-plastic analysis instead of solid element model.

  11. Research overview of design method of super light multi-hole class- honeycomb sandwich structure materials

    Directory of Open Access Journals (Sweden)

    Xiang LI

    Full Text Available With the sandwich structure materials' application and promotion in the field of engineering continuously, existing sandwich structure material gradually cannot meet the design requirements. It is very urgent to develop new sandwich structure materials of high efficiency, energy saving and easy to process. The project puts forward and constructs a new kind of class-honeycomb sandwich structure material combined with important application backgrounds that super light and high strength metal sandwich structure materials are applied into the high weight and high energy consumption equipments of automobile, aerospace and machinery and so on. This research involve: mechanical properties equivalent method for the class-honeycomb sandwich structure and its core; Strength, stiffness and inherent frequency characteristic and failure criterions of the class-honeycomb sandwich structure; based on the failure criterions constructing the multiple-constraint models of the class-honeycomb sandwich structure. The research tries to put forward a new method for innovative design of lightweight material and structure and new ideas of lightweight technology research in theory and practice.

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    2014-05-01

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

  14. Measuring Cohesive Laws for Interfaces in Sandwich Structures

    DEFF Research Database (Denmark)

    Lundsgaard-Larsen, Christian; Sørensen, Bent F.; Berggreen, Carl Christian

    2006-01-01

    mixities. The sandwich specimens consists of glass fiber faces and Divinycell H200 foam core with a pre-crack between face and core made with teflon film. Arbitrary stiffening of the sandwich faces with steel bars adhered to the faces reduces rotations and ensures that the method is useable for a wide...

  15. Orthogonal model and experimental data for analyzing wood-fiber-based tri-axial ribbed structural panels in bending

    Science.gov (United States)

    Jinghao Li; John F. Hunt; Shaoqin Gong; Zhiyong Cai

    2017-01-01

    This paper presents an analysis of 3-dimensional engineered structural panels (3DESP) made from wood-fiber-based laminated paper composites. Since the existing models for calculating the mechanical behavior of core configurations within sandwich panels are very complex, a new simplified orthogonal model (SOM) using an equivalent element has been developed. This model...

  16. Effects of face sheet damage on residual strength of GRP sandwich panels in naval ships

    DEFF Research Database (Denmark)

    Hayman, Brian; Echtermeyer, Andreas T.; Berggreen, Christian

    2010-01-01

    been obtained for a set of sandwich materials that are representative for the vessels in question. The face sheet materials are glass-reinforced plastics (GRP) with non-crimp fabrics and two different types of vinylester resin. The core materials are PVC foams. Impact damage by sharp and blunt objects...

  17. High Strength Wood-based Sandwich Panels reinforced with fiberglass and foam

    Science.gov (United States)

    Jinghao Li; John F. Hunt; Shaoqin Gong; Zhiyong Cai

    2014-01-01

    Mechanical analysis is presented for new high-strengthsandwich panels made from wood-based phenolic impregnated laminated paper assembled with an interlocking tri-axial ribbed core. Four different panel configurations were tested, including panels with fiberglass fabric bonded to both outside faces with self-expanding urethane foam used to fill the ribbed core. The...

  18. Structural Response of Marine Sandwich Panels to Uniform Pressure Loading

    Science.gov (United States)

    1990-06-01

    Fiber-Resin Composites", ASTM D3039 -76 (Reapproved 1989), 1989 Annual Book of ASTM Standards , Vol. 15.03, American Society for Testing and Materials...31. "Specific Gravity and Density of Plastics by Displacement", ASTM D792-86, 1989 Annual Book of ASTM Standards , Vol. 8.01, American Society for...Book of ASTM Standards , Vol. 8.02, American Society for Testing and Materials, Philadelphia, PA, 1989, pp. 352-353. 33. "Fiber Content of Resin-Matrix

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

    Science.gov (United States)

    Tan, Seng

    2012-01-01

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

  20. Measuring Moisture Levels in Graphite Epoxy Composite Sandwich Structures

    Science.gov (United States)

    Nurge, Mark; Youngquist, Robert; Starr, Stanley

    2011-01-01

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

  1. Numerical modeling of sandwich panel response to ballistic loading - energy balance for varying impactor geometries

    DEFF Research Database (Denmark)

    Kepler, Jørgen Asbøl; Hansen, Michael Rygaard

    2007-01-01

    thickness but significantly smaller than panel length dimensions. Experimental data for the total loss in impactor kinetic energy and momentum and estimated damage energy are described. For a selection of impactor tip shapes, the numerical model is used to evaluate different simplified force histories...... between the impactor and the panel during penetration. The force histories are selected from a primary criterion of conservation of linear momentum in the impactor-panel system, and evaluated according to agreement with the total measured energy balance....

  2. Metal foam sandwich structure as a high temperature heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Salimijazi, H.R.; Pershin, L.; Coyle, T.W.; Mostaghimi, J.; Chandra, S. [Toronto Univ., ON (Canada)

    2008-07-01

    Nickel-based superalloys can be used at temperatures up to 1050 C in air. Superalloy open cell foam sheets with skin layers plasma sprayed on both sides can be used as high temperature heat exchangers provided that the two deposited skins are dense and well adhered to the open cell foam. In this study alloy 625 skins were deposited on each side of a sheet of metal foam by APS and HVOF to form a sandwich structure. Two densities of open cell foams, 20 and 10 pores per linear inch (ppi), were used in this study as the core. The initial Ni foam was converted to an alloy composition by plasma spraying aluminum and chromium on the foam's struts with subsequent diffusion/solutionizing heat treatments before the alloy 625 skins were deposited. The microstructure of the coatings and the interface between the struts and skins was investigated. A layer of Ni-Al alloy was formed near the surface of the struts as a result of the heat treatment. The foam struts were imbedded more deeply into the coatings deposited by HVOF than the coatings deposited by APS. (orig.)

  3. Effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure

    Directory of Open Access Journals (Sweden)

    Zaid N.Z.M.

    2017-01-01

    Full Text Available Sandwich structure is an attractive alternative that increasingly used in the transportation and aerospace industry. Corrugated-core with trapezoidal shape allows enhancing the damage resistance to the sandwich structure, but on the other hand, it changes the structural response of the sandwich structure. The aim of this paper is to study the effect of varying geometrical parameters of trapezoidal corrugated-core sandwich structure under compression loading. The corrugated-core specimen was fabricated using press technique, following the shape of trapezoidal shape. Two different materials were used in the study, glass fibre reinforced plastic (GFRP and carbon fibre reinforced plastic (CFRP. The result shows that the mechanical properties of the core in compression loading are sensitive to the variation of a number of unit cells and the core thickness.

  4. Stress Distribution on Sandwich Structure with Triangular Grid Cores Suffered from Bending Load

    Directory of Open Access Journals (Sweden)

    Cui Xu

    2015-01-01

    Full Text Available Triangular grid reinforced by carbon fiber/epoxy (CF/EP was designed and manufactured. The sandwich structure was prepared by gluing the core and composite skins. The mechanical properties of the sandwich structure were investigated by the finite element analysis (FEA and three-point bending methods. The calculated bending stiffness and core shear stress were compared to the characteristics of a honeycomb sandwich structure. The results indicated that the triangular core ultimately failed under a bending load of 11000 N; the principal stress concentration was located at the loading region; and the cracks occurred on the interface top skin and triangular core. In addition, the ultimate stress bearing of the sandwich structure was 8828 N. The experimental results showed that the carbon fiber reinforced triangular grid was much stiffer and stronger than the honeycomb structure.

  5. Modelling of Debond and Crack Propagation in Sandwich Structures Using Fracture and Damage Mechanics

    DEFF Research Database (Denmark)

    Berggreen, C.; Simonsen, Bo Cerup; Toernqvist, Rikard

    2003-01-01

    Skin-core de-bonding or core crack propagation will often be dominating mechanisms in the collapse modes of sandwich structures. This paper presents two different methods for prediction of crack propagation in a sandwich structure: a fracture mechanics approach, where a new mode-mix method...... is presented, and a local damage mechanics approach. The paper presents a real-life application example, where the superstructure in a vessel pulls the skin off the sandwich deck. The calculations show almost unstable crack growth initially followed by a stabilization, and a nearly linear relation between...

  6. Evaluation of Sandwich Structure Bonding In Out-of-Autoclave Processing

    Science.gov (United States)

    Hou, Tan-Hung; Baughman, James M.; Zimmerman, Thomas J.; Sutter, James K.; Gardner, John M.

    2010-01-01

    The out-of-autoclave-vacuum-bag-only (OOA-VBO) process is low in capital expenditures compared to the traditional autoclave, however, the material challenges for OOA-VBO workable material systems are high. Presently there are few such aerospace grade prepreg materials available commercially. In this study, we evaluated processing and properties of honeycomb sandwich structure (HC/SS) panels fabricated by co-curing composite face sheet with adhesives by the OOA-VBO process in an oven. The prepreg materials were IM7/MTM 45-1 and T40-800B/5320. Adhesives studied were AF-555M, XMTA-241/PM15, FM-309-1M and FM-300K. Aluminum H/C cores with and without perforations were included. It was found that adhesives in IM7/MTM 45-1/AF-555M, T40-800B/5320/FM 309-1M and T40-800B/5320/FM-300K panels all foamed but yielded high flatwise tensile (FWT) strength values above 8,275 kPA (1,200 psi). IM7/MTM 45-1/XMTA-241/PM15 did not foam, yet yielded a low FWT strength. SEM photomicrographs revealed that the origin of this low strength was poor adhesion in the interfaces between the adhesive and face sheet composite due to poor wetting associated with the high initial viscosity of the XMTA-241/PM15 adhesive.

  7. Measurement of shear strength resistance in flexion test on PUR sandwich panels: analysis of difficulties and finite element method simulation

    Directory of Open Access Journals (Sweden)

    J. M. Chillón Moreno

    2017-09-01

    Full Text Available The use of the composite construction elements combining different materials with complementary characteristics, it has spread increasingly. The sandwich panels composed by external metallic sheets that they contributes resistance and core of rigid insulating thermal foam, that provides qualities that improve the thermal comfort inside all kinds of constructions. They are in use in closings and covers that shape the surrounding one of the buildings. Of the different quality controls to which they have to surrender. In this article one proposes an improvement to the indicated one in the procedure for the determination of the resistance to the shear strength, Managing to avoid many anomalous results obtained by the utilization of rigid plates in the supports. Finally, so much the problem observed as the proposed solution, they are modeled and simulate by means of the method of finite elements.

  8. Vibration Characteristics Determined for Stainless Steel Sandwich Panels With a Metal Foam Core for Lightweight Fan Blade Design

    Science.gov (United States)

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

    2004-01-01

    The goal of this project at the NASA Glenn Research Center is to provide fan materials that are safer, weigh less, and cost less than the currently used titanium alloy or polymer matrix composite fans. The proposed material system is a sandwich fan construction made up of thin solid face sheets and a lightweight metal foam core. The stiffness of the sandwich structure is increased by separating the two face sheets by the foam layer. The resulting structure has a high stiffness and lighter weight in comparison to the solid facesheet material alone. The face sheets carry the applied in-plane and bending loads (ref. 1). The metal foam core must resist the transverse shear and transverse normal loads, as well as keep the facings supported and working as a single unit. Metal foams have ranges of mechanical properties, such as light weight, impact resistance, and vibration suppression (ref. 2), which makes them more suitable for use in lightweight fan structures. Metal foams have been available for decades (refs. 3 and 4), but the difficulties in the original processes and high costs have prevented their widespread use. However, advances in production techniques and cost reduction have created a new interest in this class of materials (ref. 5). The material chosen for the face sheet and the metal foam for this study was the aerospace-grade stainless steel 17-4PH. This steel was chosen because of its attractive mechanical properties and the ease with which it can be made through the powder metallurgy process (ref. 6). The advantages of a metal foam core, in comparison to a typical honeycomb core, are material isotropy and the ease of forming complex geometries, such as fan blades. A section of a 17-4PH sandwich structure is shown in the following photograph. Part of process of designing any blade is to determine the natural frequencies of the particular blade shape. A designer needs to predict the resonance frequencies of a new blade design to properly identify a useful

  9. Damage behavior of honeycomb sandwich structure under low-energy impact

    Directory of Open Access Journals (Sweden)

    Cheng Jialin

    2017-01-01

    Full Text Available Honeycomb sandwich structure is widely used in aircrafts and ships to absorb impact energy. Damage caused by low-energy impact is difficult to investigate, but will significantly reduce the strength of the sandwich structure. This paper presented a systematical experimental study on the damage behavior of honeycomb sandwich structure under different configurations. Drop weight tests were carried out to investigate the effect of impact energy, core material and face plate structure on the dynamic response of sandwich plate. Delamination regions were obtained through ultrasonic scanning. Conclusions were made that the damage behavior of the face plate was similar with composite laminates while the energy absorption capacity was related to the parameters of the honeycomb core and the mismatch angle of the face plate.

  10. The dynamic properties of sandwich structures based on metal-ceramic foams.

    Science.gov (United States)

    2014-01-01

    The present research program has studied the fracture properties of closed pore metal-ceramic foams for their potential applications as core systems in sandwich structures. The composite foams were created at Fireline, Inc. (Youngstown, OH) using the...

  11. Blast-Resistant Improvement of Sandwich Armor Structure with Aluminum Foam Composite

    Directory of Open Access Journals (Sweden)

    Shu Yang

    2013-01-01

    Full Text Available Sandwich armor structures with aluminum foam can be utilized to protect a military vehicle from harmful blast load such as a landmine explosion. In this paper, a system-level dynamic finite element model is developed to simulate the blast event and to evaluate the blast-resistant performance of the sandwich armor structure. It is found that a sandwich armor structure with only aluminum foam is capable of mitigating crew injuries under a moderate blast load. However, a severe blast load causes force enhancement and results in much worse crew injury. An isolating layer between the aluminum foam and the vehicle floor is introduced to remediate this drawback. The results show that the blast-resistant capability of the innovative sandwich armor structure with the isolating layer increases remarkably.

  12. Insert Design and Manufacturing for Foam-Core Composite Sandwich Structures

    Science.gov (United States)

    Lares, Alan

    Sandwich structures have been used in the aerospace industry for many years. The high strength to weight ratios that are possible with sandwich constructions makes them desirable for airframe applications. While sandwich structures are effective at handling distributed loads such as aerodynamic forces, they are prone to damage from concentrated loads at joints or due to impact. This is due to the relatively thin face-sheets and soft core materials typically found in sandwich structures. Carleton University's Uninhabited Aerial Vehicle (UAV) Project Team has designed and manufactured a UAV (GeoSury II Prototype) which features an all composite sandwich structure fuselage structure. The purpose of the aircraft is to conduct geomagnetic surveys. The GeoSury II Prototype serves as the test bed for many areas of research in advancing UAV technologies. Those areas of research include: low cost composite materials manufacturing, geomagnetic data acquisition, obstacle detection, autonomous operations and magnetic signature control. In this thesis work a methodology for designing and manufacturing inserts for foam-core sandwich structures was developed. The results of this research work enables a designer wishing to design a foam-core sandwich airframe structure, a means of quickly manufacturing optimized inserts for the safe introduction of discrete loads into the airframe. The previous GeoSury II Prototype insert designs (v.1 & v.2) were performance tested to establish a benchmark with which to compare future insert designs. Several designs and materials were considered for the new v.3 inserts. A plug and sleeve design was selected, due to its ability to effectively transfer the required loads to the sandwich structure. The insert material was chosen to be epoxy, reinforced with chopped carbon fibre. This material was chosen for its combination of strength, low mass and also compatibility with the face-sheet material. The v.3 insert assembly is 60% lighter than the

  13. Testing and evaluation of a slot and tab construction technique for light-weight wood-fiber-based structural panels under bending

    Science.gov (United States)

    Jinghao Li; John F. Hunt; Shaoqin Gong; Zhiyong Cai

    2015-01-01

    This paper presented construction and strain distributions for light-weight wood-fiber-based structural panels with tri-grid core made from phenolic impregnated laminated paper composites under bending. A new fastening configuration of slots in the faces and tabs on the core was applied to the face/core interfaces of the sandwich panel in addition to epoxy resin. Both...

  14. Elevated Temperature, Residual Compressive Strength of Impact-Damaged Sandwich Structure Manufactured Out-of-Autoclave

    Science.gov (United States)

    Grimsley, Brian W.; Sutter, James K.; Burke, Eric R.; Dixon, Genevieve D.; Gyekenyesi, Thomas G.; Smeltzer, Stanley S.

    2012-01-01

    Several 1/16th-scale curved sandwich composite panel sections of a 10 m diameter barrel were fabricated to demonstrate the manufacturability of large-scale curved sections using minimum gauge, [+60/-60/0]s, toughened epoxy composite facesheets co-cured with low density (50 kilograms per cubic meters) aluminum honeycomb core. One of these panels was fabricated out of autoclave (OoA) by the vacuum bag oven (VBO) process using Cycom(Registered Trademark) T40-800b/5320-1 prepreg system while another panel with the same lay-up and dimensions was fabricated using the autoclave-cure, toughened epoxy prepreg system Cycom(Registered Trademark) IM7/977-3. The resulting 2.44 m x 2 m curved panels were investigated by non-destructive evaluation (NDE) at NASA Langley Research Center (NASA LaRC) to determine initial fabrication quality and then cut into smaller coupons for elevated temperature wet (ETW) mechanical property characterization. Mechanical property characterization of the sandwich coupons was conducted including edge-wise compression (EWC), and compression-after-impact (CAI) at conditions ranging from 25 C/dry to 150 C/wet. The details and results of this characterization effort are presented in this paper.

  15. Effect of Porosity Content of Arc-Sprayed Alloy 625 Skins on the Flexural Behavior of Nickel Foam Core Sandwich Structures

    Science.gov (United States)

    Salavati, S.; Pershin, L.; Coyle, T. W.; Mostaghimi, J.

    2015-01-01

    Metallic foam core sandwich structures have been of particular interest for engineering applications in recent decades because of their unique mechanical and physical properties. Thermal spraying techniques have been recently introduced as a novel low-cost method for production of these structures with complex shapes. One of the potential applications of the metallic foam core sandwich structures prepared by thermal spray techniques is as heat shield devices. Open porosity in the microstructure of the coating may allow the cooling efficiency of the heat shield to be improved through the film cooling phenomenon. A modified twin wire-arc spraying process was employed to deposit high temperature resistant alloy 625 coatings with a high percentage of the open porosity. The effect of skin porosity on the mechanical properties (flexural rigidity) of the sandwich structures was studied using a four-point bending test. It was concluded from the four-point bending test results that increase in the porosity content of the coatings leads to decrease in the flexural rigidity of the sandwich panels. The ductility of the porous and conventional arc-sprayed alloy 625 coatings was improved after heat treatment at 1100 °C for 3 h.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Viot P.

    2012-08-01

    Full Text Available 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.

  18. Novel Crack Stopper Concept for Lightweight Foam Cored Sandwich Structures – Experimental Validation, Fe-Modelling and Potential for Use in Structures

    DEFF Research Database (Denmark)

    Martakos, Georgios; Andreasen, Jens H.; Berggreen, Christian

    A novel crack arresting device has been implemented in foam cored composite sandwich beams panels and tested under both static and fatigue loading conditions. Fatigue crack propagation was induced in the face-core interface of the sandwich panels which met the crack arrester. The effect of the em......A novel crack arresting device has been implemented in foam cored composite sandwich beams panels and tested under both static and fatigue loading conditions. Fatigue crack propagation was induced in the face-core interface of the sandwich panels which met the crack arrester. The effect...... of the embedded crack arresters was evaluated in terms of the achieved enhancement of the damage tolerance of the tested sandwich beams and panels. Finite element (FE) modelling of the experimental setups was used for predicting propagation rates and direction of the crack growth. The FE model predicts the energy...... sandwich beam and panel specimens subjected to fatigue loading conditions. The effect of the crack arresters on the fatigue life is analysed, and the predictive results are subsequently compared with the observations from fatigue tests. Overall it was demonstrated that the proposed crack arrester device...

  19. Finite element modeling approach and performance evaluation of fiber reinforced polymer sandwich bridge panels : final report.

    Science.gov (United States)

    2009-08-01

    In the United States, about 27% of the bridges are classified as structurally deficient or functionally obsolete. : Bridge owners are continually investigating methods to effectively retrofit existing bridges, or to economically replace : them with n...

  20. Finite element modeling approach and performance evaluation of fiber reinforced polymer sandwich bridge panels : summary.

    Science.gov (United States)

    2009-08-01

    In the United States, about 27% of the bridges are classified as structurally deficient or functionally obsolete. Bridge owners are continually investigating methods to effectively retrofit existing bridges, or to economically replace them with new o...

  1. Electromagnetic waves reflection, transmission and absorption by graphene - magnetic semiconductor - graphene sandwich-structure in magnetic field: Faraday geometry

    OpenAIRE

    Kuzmin, Dmitry A.; Bychkov, Igor V.; Shavrov, Vladimir G.

    2014-01-01

    Electrodynamic properties of the graphene - magnetic semiconductor - graphene sandwich-structure have been investigated theoretically with taking into account the dissipation processes. Influence of graphene layers on electromagnetic waves propagation in graphene - semi-infinte magnetic semiconductor and graphene - magnetic semiconductor - graphene sandwich-structure has been analyzed. Frequency and field dependences of the reflectance, transmittance and absorbtance of electromagnetic waves b...

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

    Science.gov (United States)

    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.

  3. Performance and Characterization of Shear Ties for Use in Insulated Precast Concrete Sandwich Wall Panels

    Science.gov (United States)

    2010-11-01

    prestressed concrete ; composite; test; constitutive model U U U UU 21 Paul Sheppard Reset To be submitted to ASCE Structural Journal Page 1... Prestressed Concrete , Composite, Test, Constitutive 19 Model 20 21 1 Associate Professor...computes the shear demand 22 from the flexural capacity of the section. This method is recommended by the Precast/ Prestressed 23 Concrete Institute (PCI

  4. Photo-induced currents in the sandwich metal-ferroelectric-metal structure

    Science.gov (United States)

    Ivanov, V.; Karpets, Yu; Perkov, Yu

    2017-01-01

    It was described the photoelectric effect in thin sandwich metal-ferroelectric-metal system. The effect was observed in doped lithium niobate crystals with two electrodes of different metals. The effect is observed only in doped lithium niobate crystals and has a maximum for concentrations of impurities of iron around 0.3 % weight. This paper proposed thermal model of the investigated phenomena resulting from field contact potential difference on the borders of section of metal-ferroelectric material. The results obtained can be used to develop radiation receivers, as well as in the interpretation of experimental results on studying the properties of sandwiched metal-ferroelectric-metal structure.

  5. Combining photocatalytic hydrogen generation and capsule storage in graphene based sandwich structures

    Science.gov (United States)

    Yang, Li; Li, Xiyu; Zhang, Guozhen; Cui, Peng; Wang, Xijun; Jiang, Xiang; Zhao, Jin; Luo, Yi; Jiang, Jun

    2017-07-01

    The challenge of safe hydrogen storage has limited the practical application of solar-driven photocatalytic water splitting. It is hard to isolate hydrogen from oxygen products during water splitting to avoid unwanted reverse reaction or explosion. Here we propose a multi-layer structure where a carbon nitride is sandwiched between two graphene sheets modified by different functional groups. First-principles simulations demonstrate that such a system can harvest light and deliver photo-generated holes to the outer graphene-based sheets for water splitting and proton generation. Driven by electrostatic attraction, protons penetrate through graphene to react with electrons on the inner carbon nitride to generate hydrogen molecule. The produced hydrogen is completely isolated and stored with a high-density level within the sandwich, as no molecules could migrate through graphene. The ability of integrating photocatalytic hydrogen generation and safe capsule storage has made the sandwich system an exciting candidate for realistic solar and hydrogen energy utilization.

  6. Combining photocatalytic hydrogen generation and capsule storage in graphene based sandwich structures.

    Science.gov (United States)

    Yang, Li; Li, Xiyu; Zhang, Guozhen; Cui, Peng; Wang, Xijun; Jiang, Xiang; Zhao, Jin; Luo, Yi; Jiang, Jun

    2017-07-06

    The challenge of safe hydrogen storage has limited the practical application of solar-driven photocatalytic water splitting. It is hard to isolate hydrogen from oxygen products during water splitting to avoid unwanted reverse reaction or explosion. Here we propose a multi-layer structure where a carbon nitride is sandwiched between two graphene sheets modified by different functional groups. First-principles simulations demonstrate that such a system can harvest light and deliver photo-generated holes to the outer graphene-based sheets for water splitting and proton generation. Driven by electrostatic attraction, protons penetrate through graphene to react with electrons on the inner carbon nitride to generate hydrogen molecule. The produced hydrogen is completely isolated and stored with a high-density level within the sandwich, as no molecules could migrate through graphene. The ability of integrating photocatalytic hydrogen generation and safe capsule storage has made the sandwich system an exciting candidate for realistic solar and hydrogen energy utilization.

  7. Piezoelectric performance of fluor polymer sandwiches with different void structures

    Science.gov (United States)

    Lou, Kexing; Zhang, Xiaoqing; Xia, Zhongfu

    2012-06-01

    Film sandwiches, consisting of two outer layers of fluoroethylenepropylene and one middle layer of patterned porous polytetrafluoroethylene, were prepared by patterning and fusion bonding. Contact charging was conducted to render the films piezoelectric. The critical voltage to trigger air breakdown in the inner voids in the fabricated films was investigated. The piezoelectric d 33 coefficients were measured employing the quasistatic method and dielectric resonance spectrum. The results show that the critical voltage for air breakdown in the inner voids is associated with the void microstructure of the films. For the films with patterning factors of 0%, 25% and 44%, the critical values are 300, 230 and 230 kV/cm, respectively. With an increase in the patterning factor, both the piezoelectric d 33 coefficients determined from the dielectric resonance spectra and those determined from quasistatic measurements increase, which might be due to a decrease in Young's modulus for the films. The nonlinearity of d 33 becomes increasingly obvious as the patterning factor increases.

  8. Rational Design of Composite Panels

    DEFF Research Database (Denmark)

    Riber, Hans Jørgen

    1996-01-01

    A non-linear structural model for composite panels is presented. The non-linear terms in the lateral displacements are modelled as an additional set of lateral loads acting on the panel. Hence the solution is reduced to that of an equivalent panel with small displacements In order to treat sandwich...

  9. Residual dent in locally loaded foam core sandwich structures – Analysis and use for NDI

    NARCIS (Netherlands)

    Koysin, V.; Shipsha, Andrey

    2008-01-01

    This paper addresses the residual denting in the face sheet and corresponding core damage in a locally loaded flat sandwich structure with foam core. The problem is analytically considered in the context of elastic bending of the face sheet accompanied by non-linear deformation of the crushed foam

  10. Noise Reduction in Double‿Panel Structures by Cavity and Panel Resonance Control

    NARCIS (Netherlands)

    Ho, J.; Berkhoff, Arthur P.

    2011-01-01

    This paper presents an investigation of the cavity and the panel resonance control in a double‿panel structure. The double‿panel structure, which consists of two panels with air in the gap, is widely adopted in many applications such as aerospace due to its light weight and effective

  11. Cavity Control and Panel Control Strategies in Double-Panel Structures for Transmitted Noise Reduction

    NARCIS (Netherlands)

    Ho, J.; Kalverboer, J.; Berkhoff, Arthur P.

    2012-01-01

    Investigation and comparisons of the cavity control and the panel control in a double-panel structure are presented in this paper. The double-panel structure, which comprises two panels with air in the gap, provides the advantages of low sound-transmission at high frequency, low heat-transmission

  12. Panel Resonance Control and Cavity Control in Double-Panel Structures for Active Noise Reduction

    NARCIS (Netherlands)

    Ho, J.; Berkhoff, Arthur P.

    2011-01-01

    An analytical and experimental investigation of panel resonance control and cavity control in a double-panel structure is presented in this paper. The double-panel structure, which consists of two panels with air in the gap, is widely adopted in many applications such as aerospace due to its low

  13. Fire development and wall endurance in sandwich and wood-frame structures

    Science.gov (United States)

    Carlton A. Holmes; Herbert W. Eickner; John J. Brenden; Curtis C. Peters; Robert H. White

    1980-01-01

    Large-scale fire tests were conducted on seven 16- by 24-foot structures. Four of these structures were of sandwich construction with cores of plastic or paper honeycomb and three were of wood-frame construction. The wasss were loaded to a computer design loading, and the fire endurance determined under a fire exposure from a typical building contents loading of 4-1/2...

  14. 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

    Science.gov (United States)

    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.

  15. Comparisons between various cavity and panel noise reduction control in double-panel structures

    NARCIS (Netherlands)

    Ho, J.; Kalverboer, J.; Berkhoff, Arthur P.

    2012-01-01

    This paper presents comparisons between various panel and cavity resonance control methods to reduce the transmitted sound in a double-panel structure. The double-panel, which consists of two panels with air in the gap, has the advantages of low weight and effective transmission-loss at high

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  18. A novel sandwich differential capacitive accelerometer with symmetrical double-sided serpentine beam-mass structure

    Science.gov (United States)

    Xiao, D. B.; Li, Q. S.; Hou, Z. Q.; Wang, X. H.; Chen, Z. H.; Xia, D. W.; Wu, X. Z.

    2016-02-01

    This paper presents a novel differential capacitive silicon micro-accelerometer with symmetrical double-sided serpentine beam-mass sensing structure and glass-silicon-glass sandwich structure. The symmetrical double-sided serpentine beam-mass sensing structure is fabricated with a novel pre-buried mask fabrication technology, which is convenient for manufacturing multi-layer sensors. The glass-silicon-glass sandwich structure is realized by a double anodic bonding process. To solve the problem of the difficulty of leading out signals from the top and bottom layer simultaneously in the sandwich sensors, a silicon pillar structure is designed that is inherently simple and low-cost. The prototype is fabricated and tested. It has low noise performance (the peak to peak value is 40 μg) and μg-level Allan deviation of bias (2.2 μg in 1 h), experimentally demonstrating the effectiveness of the design and the novel fabrication technology.

  19. Fabrication of Au/graphene oxide/Ag sandwich structure thin film and its tunable energetics and tailorable optical properties

    Directory of Open Access Journals (Sweden)

    Ruijin Hong

    2017-01-01

    Full Text Available Au/graphene oxide/Ag sandwich structure thin film was fabricated. The effects of graphene oxide (GO and bimetal on the structure and optical properties of metal silver films were investigated by X-ray diffraction (XRD, optical absorption, and Raman intensity measurements, respectively. Compared to silver thin film, Au/graphene oxide/Ag sandwich structure composite thin films were observed with wider optical absorption peak and enhanced absorption intensity. The Raman signal for Rhodamine B molecules based on the Au/graphene oxide/Ag sandwich nanostructure substrate were obviously enhanced due to the bimetal layer and GO layer with tunable absorption intensity and fluorescence quenching effects.

  20. Fluxless Brazing of Large Structural Panels

    Science.gov (United States)

    Beuyukian, C. S.

    1982-01-01

    Fluxless brazing is used in fabricating aluminum structural panels that withstand high internal pressure. Aluminum sheet of structural thickness with 4045 aluminum/silicon-braze-alloy cladding is brazed to corrugated "fin stock" having channels 0.001 inch (0.03mm) high by same width. Process is carried out in an inert (argon) atmosphere in a retort furnace. Filler bars are used in some channels to prevent fin stock from collapsing as pressure is applied.

  1. Modular FRP sandwich structures for building floor construction

    OpenAIRE

    Satasivam, Sindu Saprina

    2017-01-01

    Fibre reinforced polymers (FRP) have many advantageous properties compared to traditional steel and concrete, such as lightness in weight and corrosion resistance. FRP is high in strength and, when used as load-bearing members in building structures, can also provide function integration (such as thermal insulation) and environmental benefits (especially when glass fibres are used, i.e. glass fibre reinforced polymers or GFRP). This makes GFRP a promising structural material for building floo...

  2. Buckyball sandwiches.

    Science.gov (United States)

    Mirzayev, Rasim; Mustonen, Kimmo; Monazam, Mohammad R A; Mittelberger, Andreas; Pennycook, Timothy J; Mangler, Clemens; Susi, Toma; Kotakoski, Jani; Meyer, Jannik C

    2017-06-01

    Two-dimensional (2D) materials have considerably expanded the field of materials science in the past decade. Even more recently, various 2D materials have been assembled into vertical van der Waals heterostacks, and it has been proposed to combine them with other low-dimensional structures to create new materials with hybridized properties. We demonstrate the first direct images of a suspended 0D/2D heterostructure that incorporates C 60 molecules between two graphene layers in a buckyball sandwich structure. We find clean and ordered C 60 islands with thicknesses down to one molecule, shielded by the graphene layers from the microscope vacuum and partially protected from radiation damage during scanning transmission electron microscopy imaging. The sandwich structure serves as a 2D nanoscale reaction chamber, allowing the analysis of the structure of the molecules and their dynamics at atomic resolution.

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

    Directory of Open Access Journals (Sweden)

    Castejón, L.

    1997-12-01

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

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

  4. Application of self compacting concrete for steel-concrete-steel sandwich structure; Hagane concrete full sandwich kozo eno koryudo concrete no tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, M.; Kawamura, R. [Ministry of Transport, Tokyo (Japan); Yuguchi, Y.; Yamamoto, A.

    1998-04-01

    This construction refers to a construction to fabricate a submerged box constituting a submerged tunnel. Since the construction shape thereof is of a steel-concrete-steel sandwich structure (full-sandwich structure), it is indispensable to use self compacting concrete having excellent fillability and very little volumetric change after placement. Therefore, a test construction was performed before the actual construction to select correct mixing of self compacting concrete having good quality and conduct smooth construction. The test provided a very good result presenting no unfilled portions in the actual concrete construction. This paper reports the construction result thereof. This submerged box forms a part of the submerged tunnel linking the urban area of the Kobe city and an artificial island as one of the traffic networks in the port of Kobe. Its construction shape employs the full sandwich structure. The structure is such that sheet steels in place of reinforcing bars and unreinforced concrete filled inside a steel shell enclosed by sheared reinforcing sheet steels are integrated to resist external force. 1 ref., 9 figs., 4 tabs.

  5. Voltage-induced switching dynamics based on an AZO/VO2/AZO sandwiched structure

    Science.gov (United States)

    Xiao, Han; Li, Yi; Fang, Baoying; Wang, Xiaohua; Liu, Zhimin; Zhang, Jiao; Li, Zhengpeng; Huang, Yaqin; Pei, Jiangheng

    2017-11-01

    A vanadium dioxide (VO2) thin film was prepared on an Al-doped ZnO (AZO) conductive glass substrate by DC magnetron sputtering and a post-annealing process. The AZO/VO2/AZO sandwiched structure was fabricated on the VO2/AZO composite film using photolithography and a chemical etching process. The composition, microstructure and optical properties of the VO2/AZO composite film were tested. The results showed that the VO2/AZO composite film was poly-crystalline and the AZO layer did not change the preferred growth orientation of VO2. When the voltage was applied on both of the transparent conductive layers of the AZO/VO2/AZO sandwiched structure, an abrupt change in the current was observed at different temperatures. The temperature dependence of I-V characteristic curves for the AZO/VO2/AZO sandwiched structure was analyzed. The phase transition voltage value is 7.5 V at 20 °C and decreases with increasing temperature.

  6. Nondestructive Evaluation (NDE) for Inspection of Composite Sandwich Structures

    Science.gov (United States)

    Zalameda, Joseph N.; Parker, F. Raymond

    2014-01-01

    Composite honeycomb structures are 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. Flash thermography is a commonly used technique for composite honeycomb structure inspections due to its large area and rapid inspection capability. Flash 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 discussed. Limitations to the thermal detection of the core are investigated. In addition to flash thermography, X-ray computed tomography is used. The aluminum honeycomb core provides excellent X-ray contrast compared to the composite face sheet. The X-ray CT technique was used to detect impact damage, core crushing, and skin to core disbonds. Additionally, the X-ray CT technique is used to validate the thermography results.

  7. Analysis on spectra of hydroacoustic field in sonar cavity of the sandwich elastic wall structure

    Science.gov (United States)

    Xuetao, W.; Rui, H.; Weike, W.

    2017-09-01

    In this paper, the characteristics of the mechanical self - noise in sonar array cavity are studied by using the elastic flatbed - filled rectangular cavity parameterization model. Firstly, the analytic derivation of the vibration differential equation of the single layer, sandwich elastic wall plate structure and internal fluid coupling is carried out, and the modal method is used to solve it. Finally, the spectral characteristics of the acoustic field of rectangular cavity of different elastic wallboard materials are simulated and analyzed, which provides a theoretical reference for the prediction and control of sonar mechanical self-noise. In this paper, the sandwich board as control inside the dome background noise of a potential means were discussed, the dome background noise of qualitative prediction analysis and control has important theoretical significance.

  8. Application of air-coupled acoustic thermography (ACAT) for inspection of honeycomb sandwich structures

    Science.gov (United States)

    Zalameda, Joseph N.; Winfree, William P.; Pergantis, Charles G.; DeSchepper, Daniel; Flanagan, David

    2009-05-01

    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.

  9. Application of Air Coupled Acoustic Thermography (ACAT) for Inspection of Honeycomb Sandwich Structures

    Science.gov (United States)

    Winfree, William P.; Zalameda, Joseph N.; Pergantis, Charles; Flanagan, David; Deschepper, Daniel

    2009-01-01

    The application of a noncontact air coupled acoustic heating technique is investigated for the inspection of advanced honeycomb composite structures. A weakness in the out of plane stiffness of the structure, caused by a delamination or core damage, allows for the coupling of acoustic energy and thus this area will have a higher temperature than the surrounding area. Air coupled acoustic thermography (ACAT) measurements were made on composite sandwich structures with damage and were compared to conventional flash thermography. A vibrating plate model is presented to predict the optimal acoustic source frequency. Improvements to the measurement technique are also discussed.

  10. Clay Nanocomposite/Aerogel Sandwich Structures for Cryotanks

    Science.gov (United States)

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

    2006-01-01

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

  11. Buckling Design and Imperfection Sensitivity of Sandwich Composite Launch-Vehicle Shell Structures

    Science.gov (United States)

    Schultz, Marc R.; Sleight, David W.; Myers, David E.; Waters, W. Allen, Jr.; Chunchu, Prasad B.; Lovejoy, Andrew W.; Hilburger, Mark W.

    2016-01-01

    Composite materials are increasingly being considered and used for launch-vehicle structures. For shell structures, such as interstages, skirts, and shrouds, honeycomb-core sandwich composites are often selected for their structural efficiency. Therefore, it is becoming increasingly important to understand the structural response, including buckling, of sandwich composite shell structures. Additionally, small geometric imperfections can significantly influence the buckling response, including considerably reducing the buckling load, of shell structures. Thus, both the response of the theoretically perfect structure and the buckling imperfection sensitivity must be considered during the design of such structures. To address the latter, empirically derived design factors, called buckling knockdown factors (KDFs), were developed by NASA in the 1960s to account for this buckling imperfection sensitivity during design. However, most of the test-article designs used in the development of these recommendations are not relevant to modern launch-vehicle constructions and material systems, and in particular, no composite test articles were considered. Herein, a two-part study on composite sandwich shells to (1) examine the relationship between the buckling knockdown factor and the areal mass of optimized designs, and (2) to interrogate the imperfection sensitivity of those optimized designs is presented. Four structures from recent NASA launch-vehicle development activities are considered. First, designs optimized for both strength and stability were generated for each of these structures using design optimization software and a range of buckling knockdown factors; it was found that the designed areal masses varied by between 6.1% and 19.6% over knockdown factors ranging from 0.6 to 0.9. Next, the buckling imperfection sensitivity of the optimized designs is explored using nonlinear finite-element analysis and the as-measured shape of a large-scale composite cylindrical

  12. Manufacture of Green-Composite Sandwich Structures with Basalt Fiber and Bioepoxy Resin

    Directory of Open Access Journals (Sweden)

    J. P. Torres

    2013-01-01

    Full Text Available Nowadays, there is a growing interest for the use and development of materials synthesized from renewable sources in the polymer composites manufacturing industry; this applies for both matrix and reinforcement components. In the present research, a novel basalt fibre reinforced (BFR bioepoxy green composite is proposed as an environmentally friendly alternative to traditional petroleum-derived composites. In addition, this material system was combined with cork as core material for the fabrication of fibre composite sandwich structures. Mechanical properties of both skin and core materials were assessed through flexural and tensile tests. Finite element (FEM simulations for the mechanical stress analysis of the sandwich material were carried out, and a maximum allowable shear stress for material failure under bending loads was established. Permeability measurements of the basalt fabrics were carried out in order to perform numerical simulations of liquid composite moulding (LCM processes on the PAM-RTM software. The proposed green-composite sandwich material was used for the fabrication of a longboard as a case study for a sports equipment application. Numerical simulations of the mould filling stage allowed the determination of an optimal mould filling strategy. Finally, the load-bearing capacity of the board was studied by means of FEM simulations, and the presented design proved to be acceptable for service.

  13. Additive-manufactured sandwich lattice structures: A numerical and experimental investigation

    Science.gov (United States)

    Fergani, Omar; Tronvoll, Sigmund; Brøtan, Vegard; Welo, Torgeir; Sørby, Knut

    2017-10-01

    The utilization of additive-manufactured lattice structures in engineered products is becoming more and more common as the competitiveness of AM as a production technology has increased during the past several years. Lattice structures may enable important weight reductions as well as open opportunities to build products with customized functional properties, thanks to the flexibility of AM for producing complex geometrical configurations. One of the most critical aspects related to taking AM into new application areas—such as safety critical products—is currently the limited understanding of the mechanical behavior of sandwich-based lattice structure mechanical under static and dynamic loading. In this study, we evaluate manufacturability of lattice structures and the impact of AM processing parameters on the structural behavior of this type of sandwich structures. For this purpose, we conducted static compression testing for a variety of geometry and manufacturing parameters. Further, the study discusses a numerical model capable of predicting the behavior of different lattice structure. A reasonably good correlation between the experimental and numerical results was observed.

  14. Shape and Stress Sensing of Multilayered Composite and Sandwich Structures Using an Inverse Finite Element Method

    Science.gov (United States)

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

    2013-01-01

    The marked increase in the use of composite and sandwich material systems in aerospace, civil, and marine structures leads to the need for integrated Structural Health Management systems. A key capability to enable such systems is the real-time reconstruction of structural deformations, stresses, and failure criteria that are inferred from in-situ, discrete-location strain measurements. This technology is commonly referred to as shape- and stress-sensing. Presented herein is a computationally efficient shape- and stress-sensing methodology that is ideally suited for applications to laminated composite and sandwich structures. The new approach employs the inverse Finite Element Method (iFEM) as a general framework and the Refined Zigzag Theory (RZT) as the underlying plate theory. A three-node inverse plate finite element is formulated. The element formulation enables robust and efficient modeling of plate structures instrumented with strain sensors that have arbitrary positions. The methodology leads to a set of linear algebraic equations that are solved efficiently for the unknown nodal displacements. These displacements are then used at the finite element level to compute full-field strains, stresses, and failure criteria that are in turn used to assess structural integrity. Numerical results for multilayered, highly heterogeneous laminates demonstrate the unique capability of this new formulation for shape- and stress-sensing.

  15. Esthetic enhancement of concrete structures using ferro-cement panels.

    Science.gov (United States)

    1974-01-01

    An investigation of ferro-cement indicates that when used in colored panels, such panels can be used to enhance the appearance of concrete structures. The panels are simply made, light in weight, and easily attached to either old or new structures. W...

  16. Employment of a metal microgrid as a front electrode in a sandwich-structured photodetector.

    Science.gov (United States)

    Zhang, Junying; Cai, Chao; Pan, Feng; Hao, Weichang; Zhang, Weiwei; Wang, Tianmin

    2009-07-01

    A highly UV-transparent metal microgrid was prepared and employed as the front electrode in a sandwich-structured ultraviolet (UV) photodetector using TiO(2) thin film as the semiconductor layer. The photo-generated charger carriers travel a shorter distance before reaching the electrodes in comparison with a photodetector using large-spaced interdigitated metal electrodes (where distance between fingers is several to tens of micrometers) on the surface of the semiconductor film. This photodetector responds to UV light irradiation, and the photocurrent intensity increases linearly with the irradiation intensity below 0.2 mW/cm(2).

  17. Validation and implementation of sandwich structure bottom plate to rib weld joint in the base section of ITER Cryostat

    Energy Technology Data Exchange (ETDEWEB)

    Prajapati, Rajnikant, E-mail: rajnikant@iter-india.org [ITER-India, Institute For Plasma Research, A-29, GIDC Electronics Estate, Sector-25, Gandhinagar 382016 (India); Bhardwaj, Anil K.; Gupta, Girish; Joshi, Vaibhav; Patel, Mitul; Bhavsar, Jagrut; More, Vipul; Jindal, Mukesh; Bhattacharya, Avik; Jogi, Gaurav; Palaliya, Amit; Jha, Saroj; Pandey, Manish [ITER-India, Institute For Plasma Research, A-29, GIDC Electronics Estate, Sector-25, Gandhinagar 382016 (India); Jadhav, Pandurang; Desai, Hemal [Larsen & Toubro Limited, Heavy Engineering, Hazira Manufacturing Complex, Gujarat (India)

    2016-11-01

    Highlights: • ITER Cryostat base section sandwich structure bottom plate to rib weld joint is qualified through mock-up. • Established welding sequence was successfully implemented on all six sectors of cryostat base section. • Each layer liquid penetrant examination has been carried out for these weld joints and found satisfactory. - Abstract: Cryostat is a large stainless steel vacuum vessel providing vacuum environment to ITER machine components. The cryostat is ∼30 m in diameter and ∼30 m in height having variable thickness from 25 mm to 180 mm. Sandwich structure of cryostat base section withstands vacuum loading and limits the deformation under service conditions. Sandwich structure consists of top and bottom plates internally strengthened with radial and circular ribs. In current work, sandwich structure bottom plate to rib weld joint has been designed with full penetration joint as per ITER Vacuum Handbook requirement considering nondestructive examinations and welding feasibility. Since this joint was outside the scope of ASME Section VIII Div. 2, it was decided to validate through mock-up of bottom plate to rib joint. Welding sequence was established to control the distortion. Tensile test, macro-structural examination and layer by layer LPE were carried out for validation of this weld joint. However possibility of ultrasonic examination method was also investigated. The test results from the welded joint mock-up were found to confirm all code and specification requirements. The same was implemented in first sector (0–60°) of base section sandwich structure.

  18. Laser cutting sandwich structure glass-silicon-glass wafer with laser induced thermal-crack propagation

    Science.gov (United States)

    Cai, Yecheng; Wang, Maolu; Zhang, Hongzhi; Yang, Lijun; Fu, Xihong; Wang, Yang

    2017-08-01

    Silicon-glass devices are widely used in IC industry, MEMS and solar energy system because of their reliability and simplicity of the manufacturing process. With the trend toward the wafer level chip scale package (WLCSP) technology, the suitable dicing method of silicon-glass bonded structure wafer has become necessary. In this paper, a combined experimental and computational approach is undertaken to investigate the feasibility of cutting the sandwich structure glass-silicon-glass (SGS) wafer with laser induced thermal-crack propagation (LITP) method. A 1064 nm semiconductor laser cutting system with double laser beams which could simultaneously irradiate on the top and bottom of the sandwich structure wafer has been designed. A mathematical model for describing the physical process of the interaction between laser and SGS wafer, which consists of two surface heating sources and two volumetric heating sources, has been established. The temperature stress distribution are simulated by using finite element method (FEM) analysis software ABAQUS. The crack propagation process is analyzed by using the J-integral method. In the FEM model, a stationary planar crack is embedded in the wafer and the J-integral values around the crack front edge are determined using the FEM. A verification experiment under typical parameters is conducted and the crack propagation profile on the fracture surface is examined by the optical microscope and explained from the stress distribution and J-integral value.

  19. Material Based Structure Design: Numerical Analysis Thermodynamic Response of Thermal Pyrolytic Graphite /Al Sandwich Composites

    Science.gov (United States)

    Wang, Junxia; Yan, Shilin; Yu, Dingshan

    2016-12-01

    Amine-grafted multiwalled carbon nanotubes (MWCNTs) based thermally conductive adhesive (TCA) was studied in the previous paper and applied here in thermal pyrolytic graphite (TPG)/Al radiator due to its high thermal conductivity, toughness and cohesiveness. In this paper, in an attempt to confirm the application of TCA to TPG/Al sandwich radiator, the thermodynamic response in TPG/Al sandwich composites associated with key material properties and structural design was investigated using finite element simulation with commercial available ANSYS software. The induced thermal stress in TCA layer is substantial due to the thermal expansion mismatch between Al plate and TPG. The maximum thermal stress is located near the edge of TCA layer with the von Mises stress value of 4.02 MPa and the shear stress value of 1.66 MPa. The reasonable adjustment of physical-mechanical properties including thermal conductivity, thermal expansion, Young,s modulus and the thickness of TCA layer, Al plate and TPG are beneficial for reducing the temperature of the top surface of the upper skin and their effects on the reduction of thermal structural response in some ways. These findings will highlight the structural optimization of TPG/Al radiator for future application.

  20. Structural panel for engineering applications and method for manufacturing such a structural panel

    NARCIS (Netherlands)

    Guerdal, Z.; Vasiliev, V.

    2009-01-01

    The invention relates to a structural panel comprising a core of fibre material and outer layers on opposite sides of the core, wherein the core of fibre material is received in preshaped grooves provided in one outer layer's surface, the remaining area in said grooves being completely filled with

  1. Amorphous GeOx-Coated Reduced Graphene Oxide Balls with Sandwich Structure for Long-Life Lithium-Ion Batteries.

    Science.gov (United States)

    Choi, Seung Ho; Jung, Kyeong Youl; Kang, Yun Chan

    2015-07-01

    Amorphous GeOx-coated reduced graphene oxide (rGO) balls with sandwich structure are prepared via a spray-pyrolysis process using polystyrene (PS) nanobeads as sacrificial templates. This sandwich structure is formed by uniformly coating the exterior and interior of few-layer rGO with amorphous GeOx layers. X-ray photoelectron spectroscopy analysis reveals a Ge:O stoichiometry ratio of 1:1.7. The amorphous GeOx-coated rGO balls with sandwich structure have low charge-transfer resistance and fast Li(+)-ion diffusion rate. For example, at a current density of 2 A g(-1), the GeOx-coated rGO balls with sandwich and filled structures and the commercial GeO2 powders exhibit initial charge capacities of 795, 651, and 634 mA h g(-1), respectively; the corresponding 700th-cycle charge capacities are 758, 579, and 361 mA h g(-1). In addition, at a current density of 5 A g(-1), the rGO balls with sandwich structure have a 1600th-cycle reversible charge capacity of 629 mA h g(-1) and a corresponding capacity retention of 90.7%, as measured from the maximum reversible capacity at the 100th cycle.

  2. Negligible environmental sensitivity of graphene in a hexagonal boron nitride/graphene/h-BN sandwich structure.

    Science.gov (United States)

    Wang, Lei; Chen, Zheyuan; Dean, Cory R; Taniguchi, Takashi; Watanabe, Kenji; Brus, Louis E; Hone, James

    2012-10-23

    Using Raman spectroscopy, we study the environmental sensitivity of mechanically exfoliated and electrically floating single-layer graphene transferred onto a hexagonal boron nitride (h-BN) substrate, in comparison with graphene deposited on a SiO(2) substrate. In order to understand and isolate the substrate effect on graphene electrical properties, we model and correct for Raman optical interference in the substrates. As-deposited and unannealed graphene shows a large I(2D)/I(G) ratio on both substrates, indicating extremely high quality, close to that of graphene suspended in vacuum. Thermal annealing strongly activates subsequent environmental sensitivity on the SiO(2) substrate; such activation is reduced but not eliminated on the h-BN substrate. In contrast, in a h-BN/graphene/h-BN sandwich structure, with graphene protected on both sides, graphene remains pristine despite thermal processing. Raman data provide a deeper understanding of the previously observed improved graphene electrical conductivity on h-BN substrates. In the sandwich structure, the graphene 2D Raman feature has a higher frequency and narrower line width than in pristine suspended graphene, implying that the local h-BN environment modestly yet measurably changes graphene electron and phonon dispersions.

  3. A Comparative Study on Damage Mechanism of Sandwich Structures with Different Core Materials under Lightning Strikes

    Directory of Open Access Journals (Sweden)

    Jiangyan Yan

    2017-10-01

    Full Text Available Wind turbine blades are easily struck by lightning, a phenomenon that has attracted more and more attention in recent years. On this subject a large current experiment was conducted on three typical blade sandwich structures to simulate the natural lightning-induced arc effects. The resulting damage to different composite materials has been compared: polyvinyl chloride (PVC and polyethylene terephthalate (PET suffered pyrolysis and cracks inside, while the damage to balsa wood was fibers breaking off and large delamination between it and the resin layer, and only a little chemical pyrolysis. To analyze the damage mechanism on sandwich structures of different materials, a finite element method (FEM model to calculate the temperature and pressure distribution was built, taking into consideration heat transfer and flow expansion due to impulse currents. According to the simulation results, PVC had the most severe temperature and pressure distribution, while PET and balsa wood were in the better condition after the experiments. The temperature distribution results explained clearly why balsa wood suffered much less chemical pyrolysis than PVC. Since balsa wood had better thermal stability than PET, the pyrolysis area of PET was obviously larger than that of balsa wood too. Increasing the volume fraction of solid components of porous materials can efficiently decrease the heat transfer velocity in porous materials. Permeability didn’t influence that much. The findings provide support for optimum material selection and design in blade manufacturing.

  4. Manufacturing and Structural Feasibility of Natural Fiber Reinforced Polymeric Structural Insulated Panels for Panelized Construction

    Directory of Open Access Journals (Sweden)

    Nasim Uddin

    2011-01-01

    Full Text Available Natural fibers are emerging in the fields of automobile and aerospace industries to replace the parts such as body panels, seats, and other parts subjected to higher bending strength. In the construction industries, they have the potential to replace the wood and oriented strand boards (OSB laminates in the structural insulated panels (SIPs. They possess numerous advantages over traditional OSB SIPs such as being environmental friendly, recyclable, energy efficient, inherently flood resistant, and having higher strength and wind resistance. This paper mainly focuses on the manufacturing feasibility and structural characterization of natural fiber reinforced structural insulated panels (NSIPs using natural fiber reinforced polymeric (NFRP laminates as skin. To account for the use of natural fibers, the pretreatments are required on natural fibers prior to use in NFRP laminates, and, to address this issue properly, the natural fibers were given bleaching pretreatments. To this end, flexure test and low-velocity impact (LVI tests were carried out on NSIPs in order to evaluate the response of NSIPs under sudden impact loading and uniform bending conditions typical of residential construction. The paper also includes a comparison of mechanical properties of NSIPs with OSB SIPs and G/PP SIPs. The results showed significant increase in the mechanical properties of resulting NSIP panels mainly a 53% increase in load-carrying capacity compared to OSB SIPs. The bending modulus of NSIPs is 190% higher than OSB SIPs and 70% weight reduction compared to OSB SIPs.

  5. A new technology for sandwich plates and structures based on the use of in-situ foamable thermoplastic films

    Science.gov (United States)

    Beukers, Adriaan

    The cost effectiveness of structures in transports is basically depending on the operational capability and availability, the so called structure effectiveness, per unit cost. These costs are mainly determined by the cost to manufacture (acquisition costs) and the costs to operate (mass) and to maintain (damage sensitivity). In this paper the attention is focused on a new approach leading to efficiency improving sandwich material concepts, structures and related manufacturing processes, satisfying the value for money criterion as formulated by the cost effectiveness criterion. The sandwich materials and technology applied are based on the use of thermoformable continuous fiber reinforced thermoplastic polymers, in particular E-glass reinforced polyetherimide (PEI).

  6. Effective thermal/mechanical properties of honeycomb core panels for hot structure applications

    NARCIS (Netherlands)

    Fatemi, J.; Lemmen, M.H.J.

    2009-01-01

    The present work addresses the computation of the effective thermal and mechanical properties of a honeycombcore sandwich panel. The panel considered has a hexagon-cell honeycomb core. An alternative method, based on the Gebhart factors within a hexagonal cell, is presented in addition to the

  7. An Investigation of The Reticulated Foam - Perforated Steel Sheet Sandwich Structure As A Blast Mitigation Media

    Science.gov (United States)

    Nguyen, Thuy-Tien Ngoc; Proud, William; Institute of Shock Physics, Imperial College London Collaboration; Royal British Legion CentreBlast Injury Studies at Imperial College London Collaboration

    2015-06-01

    Explosions have always been the main cause of injuries during battles and conflicts, with improvised explosive devices (IEDs) becoming more and more common nowadays. In this paper, the interaction between blast waves and sandwich structures of reticulated foam and perforated sheets, with varying thickness and configuration, is studied using an air-driven shock tube apparatus. The mitigation effects for primary blast injuries of these structures are discussed in terms of pulse shape, pressure magnitude as well as shock impulse. Schlieren photography together with other high-speed imaging was also used to visually investigate the matter. The results show that lower open area of perforated sheet and increased thickness of foam offer best protection. However, below a threshold thickness, no mitigation is seen. The Institute of Shock Physics acknowledges the support of AWE, Aldermaston, UK and Imperial College London. The Centre for Blast Injury Studies acknowledges the support of the Royal British Legion and Imperial College London.

  8. Sandwich structure of Pd doped nanostructure TiO2 film as O2 sensor.

    Science.gov (United States)

    Wang, Hairong; Sun, Quantao; Chen, Lei; Zhao, Yulong

    2013-09-01

    In this paper, we investigated the sensing properties of sandwich structure of TiO2/Pd/TiO2 thin films at various operating temperatures and oxygen partial pressures. The nanostructure TiO2 thin films were prepared by the sol-gel method. Various thickness of Pd buried layer was deposited by magnetron sputtering of a pure Pd target. The films were characterized using X-ray diffraction analysis and SEM. It was found that TiO2/Pd/TiO2 thin films have the p-type behavior while the pure TiO2 thin film is n-type semiconductor materials. We found that the structure of TiO2/Pd/TiO2 thin films with 10 s sputtering Pd layer has a better stability at 240 °C.

  9. A chemically stable electrolyte with a novel sandwiched structure for proton-conducting solid oxide fuel cells (SOFCs)

    KAUST Repository

    Bi, Lei

    2013-11-01

    A chemically stable electrolyte structure was developed for proton-conducting SOFCs by using two layers of stable BaZr0.7Pr 0.1Y0.2O3 -δ to sandwich a highly-conductive but unstable BaCe0.8Y0.2O 3 -δ electrolyte layer. The sandwiched electrolyte structure showed good chemical stability in both CO2 and H2O atmosphere, indicating that the BZPY layers effectively protect the inner BCY electrolyte, while the BCY electrolyte alone decomposed completely under the same conditions. Fuel cell prototypes fabricated with the sandwiched electrolyte achieved a relatively high performance of 185 mW cm- 2 at 700 C, with a high electrolyte film conductivity of 4 × 10- 3 S cm- 1 at 600 C. © 2013 Elsevier B.V.

  10. High Conductive CFRP Sandwich Technologies for Platforms

    Science.gov (United States)

    Ihle, Alexander; Hartmann, D.; Wurfl, T.; Reichmann, O.; Liedtke, V.; Tschepe, C.; Berrill, M.

    2014-06-01

    A general trend in the design of Satellites structures is to use more and more extensively CFRP materials. These materials are lighter, stiffer and have a better dimensional stability than their metallic counterparts. However, the usually used CFRP materials have a low thermal conductivity, which makes the use of these materials difficult if not impossible for all parts that must conduct and distribute heat.For such applications, aluminium skin/core panels are often used for e.g. radiative structure panels. The goal of the study was to design, manufacture and test a CFRP spacecraft sandwich panel structure (based on a shear web supporting dissipative equipments) using high conductive CFRP in order to substitute common aluminium panels.

  11. Experimental Study of the Bending Properties and Deformation Analysis of Web-Reinforced Composite Sandwich Floor Slabs with Four Simply Supported Edges.

    Directory of Open Access Journals (Sweden)

    Yujun Qi

    Full Text Available Web-reinforced composite sandwich panels exhibit good mechanical properties in one-way bending, but few studies have investigated their flexural behavior and deformation calculation methods under conditions of four simply supported edges. This paper studies the bending performance of and deformation calculation methods for two-way web-reinforced composite sandwich panels with different web spacing and heights. Polyurethane foam, two-way orthogonal glass-fiber woven cloth and unsaturated resin were used as raw materials in this study. Vacuum infusion molding was used to prepare an ordinary composite sandwich panel and 5 web-reinforced composite sandwich panels with different spacing and web heights. The panels were subjected to two-way panel bending tests with simple support for all four edges. The mechanical properties of these sandwich panels during the elastic stage were determined by applying uniformly distributed loads. The non-linear mechanical characteristics and failure modes were obtained under centrally concentrated loading. Finally, simulations of the sandwich panels, which used the mechanical model established herein, were used to deduce the formulae for the deflection deformation for this type of sandwich panel. The experimental results show that webs can significantly improve the limit bearing capacity and flexural rigidity of sandwich panels, with smaller web spacing producing a stronger effect. When the web spacing is 75 mm, the limit bearing capacity is 4.63 times that of an ordinary sandwich panel. The deduced deflection calculation formulae provide values that agree well with the measurements (maximum error <15%. The results that are obtained herein can provide a foundation for the structural design of this type of panel.

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

    Science.gov (United States)

    Ratcliffe, James G.

    2010-01-01

    This paper details part of an effort focused on the development of a standardized facesheet/core peel debonding test procedure. The purpose of the test is to characterize facesheet/core peel in sandwich structure, accomplished through the measurement of the critical strain energy release rate associated with the debonding process. The specific test method selected for the standardized test procedure utilizes a single cantilever beam (SCB) specimen configuration. The objective of the current work is to develop a method for establishing SCB specimen dimensions. This is achieved by imposing specific limitations on specimen dimensions, with the objectives of promoting a linear elastic specimen response, and simplifying the data reduction method required for computing the critical strain energy release rate associated with debonding. The sizing method is also designed to be suitable for incorporation into a standardized test protocol. Preliminary application of the resulting sizing method yields practical specimen dimensions.

  13. Damage Evolution in Composite Materials and Sandwich Structures Under Impulse Loading

    Science.gov (United States)

    Silva, Michael Lee

    Damage evolution in composite materials is a rather complex phenomenon. There are numerous failure modes in composite materials stemming from the interaction of the various constituent materials and the particular loading conditions. This thesis is concerned with investigating damage evolution in sandwich structures under repeated transient loading conditions associated with impulse loading due to hull slamming of high-speed marine craft. To fully understand the complex stress interactions, a full field technique to reveal stress or strain is required. Several full field techniques exist but are limited to materials with particular optical properties. A full field technique applicable to most materials is known as thermoelastic stress analysis (TSA) and reveals the variation in sum of principal stresses of a cyclically loaded sample by correlating the stresses to a small temperature change occurring at the loading frequency. Digital image correlation (DIC) is another noncontact full field technique that reveals the deformation field by tracking the motion of subsets of a random speckle pattern during the loading cycles. A novel experimental technique to aid in the study of damage progression that combines TSA and DIC simultaneously utilizing a single infrared camera is presented in this thesis. A technique to reliably perform DIC with an infrared (IR) camera is developed utilizing variable emissivity paint. The thermal data can then be corrected for rigid-body motion and deformation such that each pixel represents the same material point in all frames. TSA is then performed on this corrected data, reducing motion blur and increasing accuracy. This combined method with a single infrared camera has several advantages, including a straightforward experimental setup without the need to correct for geometric effects of two spatially separate cameras. Additionally, there is no need for external lighting in TSA as the measured electromagnetic radiation is emitted by the

  14. Structural Insulated Panels: Past, Present, and Future

    Directory of Open Access Journals (Sweden)

    Abang Abdullah Abang Ali

    2013-01-01

    Full Text Available Since the emergence of construction technology, construction of affordable and environmentally-sensible home at fast pace has brought dream home within the reach. Structural Insulated Panel (SIP has become a topic of interest among researchers in the recent years. SIP has the advantages of minimal material wastage and labour-savingness whilst having potential to save house builders’ time and money as well as retaining the controlled quality. Nonetheless, it suffers from few drawbacks which should be further explored by researchers in its future design. This study present a brief overview of SIP history and common methods and materials utilised for SIP production. It reviews the recent research in the field of SIP by evaluating its application and drawbacks which enable SIP designers improve on SIP. The review of evaluating SIP application and its drawbacks clearly point to the need for further studies to progress beyond the current SIP to an improved one. It might be achieved by replacement of new material with common material used as skin and core of SIP. Considerably more research will need to be done to obtain SIP universal design standard.

  15. Shear-Panel Test Fixture Eliminates Corner Stresses

    Science.gov (United States)

    Kiss, J. J.; Farley, G. L.; Baker, D. J.

    1984-01-01

    New design eliminates corner stresses while maintaining uniform stress across panel. Shear panel test fixture includes eight frames and eight corner pins. Fixture assembled in two halves with shear panel sandwiched in between. Results generated from this fixture will result in good data base for design of efficient aircraft structures and other applications.

  16. The structure of a conserved piezo channel domain reveals a topologically distinct β sandwich fold.

    Science.gov (United States)

    Kamajaya, Aron; Kaiser, Jens T; Lee, Jonas; Reid, Michelle; Rees, Douglas C

    2014-10-07

    Piezo has recently been identified as a family of eukaryotic mechanosensitive channels composed of subunits containing over 2,000 amino acids, without recognizable sequence similarity to other channels. Here, we present the crystal structure of a large, conserved extramembrane domain located just before the last predicted transmembrane helix of C. elegans PIEZO, which adopts a topologically distinct β sandwich fold. The structure was also determined of a point mutation located on a conserved surface at the position equivalent to the human PIEZO1 mutation found in dehydrated hereditary stomatocytosis patients (M2225R). While the point mutation does not change the overall domain structure, it does alter the surface electrostatic potential that may perturb interactions with a yet-to-be-identified ligand or protein. The lack of structural similarity between this domain and any previously characterized fold, including those of eukaryotic and bacterial channels, highlights the distinctive nature of the Piezo family of eukaryotic mechanosensitive channels. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Lightweight composites for modular panelized construction

    Science.gov (United States)

    Vaidya, Amol S.

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

  18. Investigation of Quasi-Static Indentation Response of Inkjet Printed Sandwich Structures under Various Indenter Geometries

    Directory of Open Access Journals (Sweden)

    Vishwesh Dikshit

    2017-03-01

    Full Text Available The objective of this investigation was to determine the quasi-static indentation response and failure mode in three-dimensional (3D printed trapezoidal core structures, and to characterize the energy absorbed by the structures. In this work, the trapezoidal sandwich structure was designed in the following two ways. Firstly, the trapezoidal core along with its facesheet was 3D printed as a single element comprising a single material for both core and facesheet (type A; Secondly, the trapezoidal core along with facesheet was 3D printed, but with variation in facesheet materials (type B. Quasi-static indentation was carried out using three different indenters, namely standard hemispherical, conical, and flat indenters. Acoustic emission (AE technique was used to capture brittle cracking in the specimens during indentation. The major failure modes were found to be brittle failure and quasi-brittle fractures. The measured indentation energy was at a maximum when using a conical indenter at 9.40 J and 9.66 J and was at a minimum when using a hemispherical indenter at 6.87 J and 8.82 J for type A and type B series specimens respectively. The observed maximum indenter displacements at failure were the effect of material variations and composite configurations in the facesheet.

  19. Investigation of Quasi-Static Indentation Response of Inkjet Printed Sandwich Structures under Various Indenter Geometries.

    Science.gov (United States)

    Dikshit, Vishwesh; Nagalingam, Arun Prasanth; Yap, Yee Ling; Sing, Swee Leong; Yeong, Wai Yee; Wei, Jun

    2017-03-14

    The objective of this investigation was to determine the quasi-static indentation response and failure mode in three-dimensional (3D) printed trapezoidal core structures, and to characterize the energy absorbed by the structures. In this work, the trapezoidal sandwich structure was designed in the following two ways. Firstly, the trapezoidal core along with its facesheet was 3D printed as a single element comprising a single material for both core and facesheet (type A); Secondly, the trapezoidal core along with facesheet was 3D printed, but with variation in facesheet materials (type B). Quasi-static indentation was carried out using three different indenters, namely standard hemispherical, conical, and flat indenters. Acoustic emission (AE) technique was used to capture brittle cracking in the specimens during indentation. The major failure modes were found to be brittle failure and quasi-brittle fractures. The measured indentation energy was at a maximum when using a conical indenter at 9.40 J and 9.66 J and was at a minimum when using a hemispherical indenter at 6.87 J and 8.82 J for type A and type B series specimens respectively. The observed maximum indenter displacements at failure were the effect of material variations and composite configurations in the facesheet.

  20. Investigation of Quasi-Static Indentation Response of Inkjet Printed Sandwich Structures under Various Indenter Geometries

    Science.gov (United States)

    Dikshit, Vishwesh; Nagalingam, Arun Prasanth; Yap, Yee Ling; Sing, Swee Leong; Yeong, Wai Yee; Wei, Jun

    2017-01-01

    The objective of this investigation was to determine the quasi-static indentation response and failure mode in three-dimensional (3D) printed trapezoidal core structures, and to characterize the energy absorbed by the structures. In this work, the trapezoidal sandwich structure was designed in the following two ways. Firstly, the trapezoidal core along with its facesheet was 3D printed as a single element comprising a single material for both core and facesheet (type A); Secondly, the trapezoidal core along with facesheet was 3D printed, but with variation in facesheet materials (type B). Quasi-static indentation was carried out using three different indenters, namely standard hemispherical, conical, and flat indenters. Acoustic emission (AE) technique was used to capture brittle cracking in the specimens during indentation. The major failure modes were found to be brittle failure and quasi-brittle fractures. The measured indentation energy was at a maximum when using a conical indenter at 9.40 J and 9.66 J and was at a minimum when using a hemispherical indenter at 6.87 J and 8.82 J for type A and type B series specimens respectively. The observed maximum indenter displacements at failure were the effect of material variations and composite configurations in the facesheet. PMID:28772649

  1. Structural composite panel performance under long-term load

    Science.gov (United States)

    Theodore L. Laufenberg

    1988-01-01

    Information on the performance of wood-based structural composite panels under long-term load is currently needed to permit their use in engineered assemblies and systems. A broad assessment of the time-dependent properties of panels is critical for creating databases and models of the creep-rupture phenomenon that lead to reliability-based design procedures. This...

  2. 'All-Metal' Aromatic Sandwich Molecules: An Electronic Structure and Transport Study.

    Science.gov (United States)

    Das, Bidisa

    2015-01-01

    Electronic structure and transport is theoretically studied for neutral, all-metal aromatic sandwich molecules, Al4MAl4 (M = Cr, Mo) along with Al4 and Al4M (M = Cr, Mo) clusters in two-probe setups with silver and gold electrodes. Detailed electronic structure and transport studies of metallaromatic Al4MAl4 molecules show high electronic conductance [2.5*10(-4) S for Al4CrAl4 and 2.9*10(-4) S for Al4MoAl4] and three conduction channels simultaneously contribute to the total transmission probability. The study of transport properties of the bare Al4 cluster and Al4M cluster also show very high electronic conductance. The neutral Al4 cluster, when connected parallel to the electrodes, four Al atoms couple to the electrode atoms and at least eight electron conduction pathways contribute simultaneously to the conductance whereas for perpendicular connectivity only three conduction channels operate. All the molecules couple strongly to the electrodes by well-defined metal-metal bonds owing to their metallic nature indicating an easier electrode integration process, and the calculated current voltage curves are almost linear till applied voltages of 1 V for Al4MAl4 (M = Cr, Mo). The electronic transport of the clusters studied here resembles the values found for metal atomic chains in break junction studies.

  3. A novel sandwich capacitive accelerometer with a symmetrical structure fabricated from a D-SOI wafer

    Science.gov (United States)

    Zhou, Xiaofeng; Che, Lufeng; Wu, Jian; Li, Xiaolin; Wang, Yuelin

    2012-08-01

    This paper presents a novel sandwich capacitance accelerometer with a symmetrical double-sided beam-mass structure. The symmetrical beam-mass structure is fabricated from a double-device-layer silicon-on-insulate (D-SOI) wafer. The proof mass is suspended by eight beams at the corners on both sides. The beams are fabricated at the device layers of the SOI wafer; the cross-section of the beams is a standard trapezoid. The thickness of the beams can be well controlled because it is determined by the thickness of the device layer in the SOI wafer, and there is no dry etching process in the accelerometer fabrication. The resonance frequency of the developed accelerometer is measured in an open-loop system by a network analyzer. The quality factor and the resonant frequency are 18 and 812 Hz, respectively. The accelerometer has an opened-loop capacitance sensitivity of 8.7 pF g-1, a closed-loop sensitivity of 1.39 V g-1 and a nonlinearity of 0.49% over the range of 1 g. The measured input, referred to as the noise floor of the accelerometers, with an interface circuit is 2.4 µg (√Hz)-1 (0-100 Hz).

  4. Simulation of Delamination-Migration and Core Crushing in a CFRP Sandwich Structure

    Science.gov (United States)

    McElroy, M.; Leone, F.; Ratcliffe, J.; Czabaj, M.; Yuan, F. G.

    2015-01-01

    Following the onset of damage caused by an impact load on a composite laminate structure, delaminations often form propagating outwards from the point of impact and in some cases can migrate via matrix cracks between plies as they grow. The goal of the present study is to develop an accurate finite element modeling technique for simulation of the delamination-migration phenomena in laminate impact damage processes. An experiment was devised where, under a quasi-static indentation load, an embedded delamination in the facesheet of a laminate sandwich specimen migrates via a transverse matrix crack and then continues to grow on a new ply interface. The quasistatic nature of the indentation results in structural behavior equivalent to that seen in low-velocity impact and also allows for highly detailed real time damage characterization. Several finite element damage simulation methods were investigated. Comparing the experimental results with those of the different models reveals certain modeling features that are important to include in a numerical simulation of delamination-migration and some that may be neglected.

  5. Effect of temperature on composite sandwich structures subjected to low velocity impact. [aircraft construction materials

    Science.gov (United States)

    Sharma, A. V.

    1980-01-01

    The effect of low velocity projectile impact on sandwich-type structural components was investigated. The materials used in the fabrication of the impact surface were graphite-, Kevlar-, and boron-fibers with appropriate epoxy matrices. The testing of the specimens was performed at moderately low- and high-temperatures as well as at room temperature to assess the impact-initiated strength degradation of the laminates. Eleven laminates with different stacking sequences, orientations, and thicknesses were tested. The low energy projectile impact is considered to simulate the damage caused by runway debris, the dropping of the hand tools during servicing, etc., on the secondary aircraft structures fabricated with the composite materials. The results show the preload and the impact energy combinations necessary to cause catastrophic failure in the laminates tested. A set of faired curves indicating the failure thresholds is shown separately for the tension-and compression-loaded laminates. The specific-strengths and -modulii for the various laminates tested are also given.

  6. Novel sandwich structure adsorptive membranes for removal of 4-nitrotoluene from water

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yuexin [College of Chemistry, Beijing Normal University, Beijing 100875 (China); School of Pharmacy, North China University of Science and Technology, Tangshan 063000 (China); Jia, Zhiqian, E-mail: zhqjia@bnu.edu.cn [College of Chemistry, Beijing Normal University, Beijing 100875 (China)

    2016-11-05

    Highlights: • Novel sandwich PES-SPES/PS-PDVB/PTFE adsorptive membranes were prepared. • The removal efficiency for 4-nitrotoluene is greater than 95% after five recycles. • The membrane showed higher adsorption capacity than that of mixed matrix membrane. - Abstract: Novel sandwich PES-SPES/PS-PDVB/PTFE adsorptive membranes were prepared by a filtration/immersion precipitation method and employed for the removal of 4-nitrotoluene from water. The static adsorption thermodynamics, kinetics, dynamic adsorption/desorption and membrane reusability were investigated. The results showed that the Freundlich model describes the adsorption isotherm satisfactorily. With increased PS-PDVB content, the maximum static adsorption capacity, partition coefficient, apparent adsorption rate constant, and dynamic adsorption capacity all significantly increased. The sandwich membranes showed much higher removal efficiency and adsorption capacity than those of mixed matrix membranes. With respect to dynamics adsorption/desorption, the sandwich membranes exhibited excellent reusability, with a removal efficiency greater than 95% even after five recycles.

  7. The structural behaviour of laminated-guadua panels under parallel plane loads

    Directory of Open Access Journals (Sweden)

    Juan Jacobo Pinilla Rodríguez

    2012-03-01

    Full Text Available The Universidad Nacional de Colombia "Analysis, Design and Materials - GIES" research group tested two types of panels made from Guadua angustifolia Kunth and poly vinyl acetate (PVA as a first step in studying the behaviour of laminated guadua frames having panels of the same material under seismic load: type 1 panels had a solid cross-section and type 2 panels a sandwich cross-section.Each type of panel had three different heights and 10 replicates were tested for each type and height (60 trials in total.Each panel’s load compared to displacement curve was found; 0.34m and 0.63m type1 panels had initial elastic behaviour followed by inelastic behaviour while 0.98 m panels made of both types had an almost completely elastic behaviour until failure. All panels became crushed at their base; however, the main failure mechanism was warping.

  8. MULTILAYERED PLATE ELEMENTS WITH NODE-DEPENDENT KINEMATICS FOR THE ANALYSIS OF COMPOSITE AND SANDWICH STRUCTURES

    Directory of Open Access Journals (Sweden)

    Stefano Valvano

    2017-04-01

    Full Text Available In this paper a new plate finite element (FE for the analysis of composite and sandwich plates is proposed. By making use of the node-variable plate theory assumptions, the new finite element allows for a simultaneous analysis of different subregions of the problem domain with different kinematics and accuracy, in a global/local sense. In particular higher-order theories with an Equivalent-Single-Layer (ESL approach are simultaneously used with advanced Layer-Wise (LW models. As a consequence, the computational costs can be reduced drastically by assuming refined theories only in those zones/nodes of the structural domain where the resulting strain and stress states present a complex distribution. On the contrary, computationally cheaper, low-order kinematic assumptions can be used in the remaining parts of the plate where a localized detailed analysis is not necessary. The primary advantage of the present variable-kinematics element and related global/local approach is that no ad-hoc techniques and mathematical artifices are required to mix the fields coming from two different and kinematically incompatible adjacent elements, because the plate structural theory varies within the finite element itself. In other words, the structural theory of the plate element is a property of the FE node in this present approach, and the continuity between two adjacent elements is ensured by adopting the same kinematics at the interface nodes. According to the Unified Formulation by Carrera, the through-the-thickness unknowns are described by Taylor polynomial expansions with ESL approach and by Legendre polynomials with LW approach. Furthermore, the Mixed Interpolated Tensorial Components (MITC method is employed to contrast the shear locking phenomenon. Several numerical investigations are carried out to validate and demonstrate the accuracy and efficiency of the present plate element, including comparison with various closed-form and FE solutions from the

  9. Development of refined models for multilayered composite and sandwich structures: analytical formulation, FEM implementation and experimental assessment

    OpenAIRE

    Iurlaro, Luigi

    2015-01-01

    Over the last three decades, composite materials have been increasingly used in different engineering field due to their high stiffness-to-weight and strength-to-weight ratios. Nowadays, relatively thick laminated composite and sandwich materials with one hundred or more layers find their applications in primary load-bearing structural components of the modern aircraft. To ensure a reliable design and failure prediction, accurate evaluation of the strain/stress state is mandatory. A high-fide...

  10. Nonlinear Thermo-mechanical Finite Element Analysis of Polymer Foam Cored Sandwich Structures including Geometrical and Material Nonlinearity

    DEFF Research Database (Denmark)

    Palleti, Hara Naga Krishna Teja; Thomsen, Ole Thybo; Taher, Siavash Talebi

    In this paper, polymer foam cored sandwich structures with fibre reinforced composite face sheets subjected to combined mechanical and thermal loads will be analysed using the commercial FE code ABAQUS® incorporating both material and geometrical nonlinearity. Large displacements and rotations...... are included in the analysis. The full nonlinear stress-strain curves up to failure will be considered for the polymer foams at different temperatures to study the effect of material nonlinearity in detail....

  11. Design of X-joints in Sandwich Structures for Naval Vessels

    DEFF Research Database (Denmark)

    Hayman, Brian; Berggreen, Christian; Lundsgaard-Larsen, Christian

    2007-01-01

    In many naval ships of fibre composite sandwich construction, an X-joint exists where the end bulkhead of the superstructure is attached to the deck, with an internal bulkhead placed in the same vertical plane below the deck. This joint is subjected to alternating tensile and compressive loading...

  12. Application and Analysis of Sandwich Elements in the Primary Structure of Large Wind Turbine Blades

    DEFF Research Database (Denmark)

    Berggreen, Christian; Branner, Kim; Jensen, Jacob Fisker

    2007-01-01

    The present work studies the advantages of applying a sandwich construction as opposed to traditional single skin composites in the flanges of a load carrying spar in a future 180 m wind turbine rotor. A parametric finite element model is used to analyze two basic designs with single skin...

  13. Transmission of Sound Through Double-Plate Panel Structures

    DEFF Research Database (Denmark)

    Dickow, Kristoffer Ahrens; Domadiya, Parthkumar Gandalal; Andersen, Lars

    2011-01-01

    In the present paper, a finite-element model of a double-plate panel is implemented to investigate the transmission of sound through a simple lightweight structure. A numerical study is performed of the following three coupling configurations: 1) Structure-borne sound via plate-stud-plate structu......In the present paper, a finite-element model of a double-plate panel is implemented to investigate the transmission of sound through a simple lightweight structure. A numerical study is performed of the following three coupling configurations: 1) Structure-borne sound via plate......-stud-plate structures without air inclusions; 2) transmission via the plate-stud-plate structure including the internal acoustic medium; 3) transmission via plate-air-plate connections in a double-leaf panel with no structural coupling between the two plates. A fully coupled analysis is performed in which solid finite...... elements are adopted for the structure, whereas the acoustic medium is discretized into fluid continuum elements. The computations are carried out in frequency domain in the low frequency range and the load acts as a diffuse sound field on one side of the panel....

  14. Accuracy of Dynamic and Acoustic Analysis of Lightweight Panel Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Dickow, Kristoffer Ahrens; Andersen, Lars Vabbersgaard

    2012-01-01

    in such buildings is important. In the lowfrequency range, prediction of sound and vibration in building structures may be achieved by finite-element analysis (FEA). The aim of this paper is to compare the two commercial codes ABAQUS and ANSYS for FEA of an acoustic-structural coupling in a timber lightweight panel...

  15. 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

    Science.gov (United States)

    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.

  16. Comparative analysis of methods and results of numerical calculations of plywood panel

    Directory of Open Access Journals (Sweden)

    Ladnykh Irene

    2017-01-01

    Full Text Available The article discusses the new type of plywood panel for low-rise building. Сalculating methods for the plywood panels are considered according with the codes of rules and the method for calculating sandwich panels with a honeycomb, proposed by Soviet scientists for aviation structures.

  17. Fuzzy Structures Analysis of Aircraft Panels in NASTRAN

    Science.gov (United States)

    Sparrow, Victor W.; Buehrle, Ralph D.

    2001-01-01

    This paper concerns an application of the fuzzy structures analysis (FSA) procedures of Soize to prototypical aerospace panels in MSC/NASTRAN, a large commercial finite element program. A brief introduction to the FSA procedures is first provided. The implementation of the FSA methods is then disclosed, and the method is validated by comparison to published results for the forced vibrations of a fuzzy beam. The results of the new implementation show excellent agreement to the benchmark results. The ongoing effort at NASA Langley and Penn State to apply these fuzzy structures analysis procedures to real aircraft panels is then described.

  18. Ultra-Lightweight Nanocomposite Foams and Sandwich Structures for Space Structures Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Space structures that are ultra-lightweight, and have gas barrier property, space durability, radiation resistance and high impact resistance are desirable to...

  19. Ultra-Lightweight Nanocomposite Foams and Sandwich Structures for Space Structures Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Space structures that are ultra-lightweight, and have gas barrier property, space durability, radiation resistance, EMI shielding, and high impact resistance are...

  20. The interfacial fracture behavior of foam core composite sandwich structures by a viscoelastic cohesive model

    Science.gov (United States)

    Sun, Shiyong; Chen, Haoran

    2011-08-01

    A sandwich beam model consisting of two face sheets and a foam core bonded by a viscoelastic adhesive layer is considered in order to investigate interfacial fracture behavior. Firstly, a cohesive zone model in conjunction with a Maxwell element in parallel, or with a Kelvin element in series, respectively, is employed to describe the characteristics of viscoelasticity for the adhesive layer. The models can be implemented into the implicit finite element code. Next, the parametric study shows that the influences of loading rates on the cohesive zone energy and strength are quite different for different models. Finally, a sandwich double cantilever beam model is adopted to simulate the interface crack growth between the face sheet and core. Numerical examples are presented for various loading rates to demonstrate the efficacy of the rate-dependent cohesive models.

  1. Mechanical properties of sandwich composite made of syntactic foam core and GFRP skins

    Directory of Open Access Journals (Sweden)

    Zulzamri Salleh

    2016-12-01

    Full Text Available Sandwich composites or sandwich panels have been widely used as potential materials or building structures and are regarded as a lightweight material for marine applications. In particular, the mechanical properties, such as the compressive, tensile and flexural behaviour, of sandwich composites formed from glass fibre sheets used as the skin and glass microballoon/vinyl ester as the syntactic foam core were investigated in this report. This syntactic foam core is sandwiched between unidirectional glass fibre reinforced plastic (GFRP using vinyl ester resins to build high performance sandwich panels. The results show that the compressive and tensile strengths decrease when the glass microballoon content is increased in syntactic foam core of sandwich panels. Moreover, compressive modulus is also found to be decreased, and there is no trend for tensile modulus. Meanwhile, the flexural stiffness and effective flexural stiffness for edgewise position have a higher bending as 50% and 60%, respectively. Furthermore, the results indicated that the glass microballoon mixed in a vinyl ester should be controlled to obtain a good combination of the tensile, compressive and flexural strength properties.

  2. High-efficiency perovskite solar cells prepared by using a sandwich structure MAI-PbI2-MAI precursor film.

    Science.gov (United States)

    Zhang, Xuhui; Ye, Jiajiu; Zhu, Liangzheng; Zheng, Haiying; Liu, Guozhen; Liu, Xuepeng; Duan, Bin; Pan, Xu; Dai, Songyuan

    2017-04-06

    Two-step deposition has been widely used in the perovskite layer preparation for perovskite solar cells due to its attractive morphology controllability. However, the limited diffusivity of CH 3 NH 3 I (MAI) might cause some PbI 2 to remain in the perovskite film. The residual PbI 2 in the perovskite film would lead to inferior performance of devices, such as, low power conversion efficiency (PCE), poor reproducibility and weak air stability. In this work, we developed a sandwich structure MAI-PbI 2 -MAI precursor film to prepare a PbI 2 -free CH 3 NH 3 PbI 3 perovskite film. In comparison to the two-step approach, the MAI-PbI 2 -MAI precursor film with a typical sandwich structure formed a uniform and pinhole-free perovskite film without any PbI 2 residue, which could significantly improve the performance of the devices. Moreover, the bottom MAI layer of the MAI-PbI 2 -MAI precursor film could improve the interfacial contact of the porous TiO 2 layer, leading to the promotion of the charge transfer and reduction of the recombination rate. Therefore, the devices fabricated from the sandwich structure MAI-PbI 2 -MAI precursor films showed dramatic improvements of open-circuit voltage (V oc ), short-circuit current density (J sc ), fill factor (FF) and PCE. As a result, a promising PCE of 17.8% with good long-term air stability was achieved for the MAI-PbI 2 -MAI precursor film based PSC, which is better than that prepared by a two-step approach.

  3. A novel method of measuring leaf epidermis and mesophyll stiffness shows the ubiquitous nature of the sandwich structure of leaf laminas in broad-leaved angiosperm species.

    Science.gov (United States)

    Onoda, Yusuke; Schieving, Feike; Anten, Niels P R

    2015-05-01

    Plant leaves commonly exhibit a thin, flat structure that facilitates a high light interception per unit mass, but may increase risks of mechanical failure when subjected to gravity, wind and herbivory as well as other stresses. Leaf laminas are composed of thin epidermis layers and thicker intervening mesophyll layers, which resemble a composite material, i.e. sandwich structure, used in engineering constructions (e.g. airplane wings) where high bending stiffness with minimum weight is important. Yet, to what extent leaf laminas are mechanically designed and behave as a sandwich structure remains unclear. To resolve this issue, we developed and applied a novel method to estimate stiffness of epidermis- and mesophyll layers without separating the layers. Across a phylogenetically diverse range of 36 angiosperm species, the estimated Young's moduli (a measure of stiffness) of mesophyll layers were much lower than those of the epidermis layers, indicating that leaf laminas behaved similarly to efficient sandwich structures. The stiffness of epidermis layers was higher in evergreen species than in deciduous species, and strongly associated with cuticle thickness. The ubiquitous nature of sandwich structures in leaves across studied species suggests that the sandwich structure has evolutionary advantages as it enables leaves to be simultaneously thin and flat, efficiently capturing light and maintaining mechanical stability under various stresses. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  4. Multifunctional sandwich composites

    Science.gov (United States)

    Vaidya, Uday K.

    2003-10-01

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

  5. Carrier trapping induced abnormal temperature dependent photoluminescence properties of novel sandwiched structure InGaN quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    He, Juan; Li, Ding; Rajabi, K.; Yang, Wei; Hu, Xiaodong [State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Liu, Lei [Suzhou Institute of Nano-tech and Nano-bionics, CAS, Suzhou 215125 (China)

    2014-04-15

    A dual-wavelength LED sample with novel sandwiched structure in high-In-content MQWs is studied by temperature dependent photoluminescence (TDPL) and the abnormal temperature dependence of emission intensity is obtained. The novel MQWs structure which contains staggered quantum wells and an ultra-thin InN interlayer in the wells shows better luminescence property than the reference sample which has conventional quantum wells. Under 325 nm continuous wave laser excitation the LED sample of novel structure exhibits unexpected increasing luminescence intensity as temperature goes up from 140 K to 220 K and reaches its maximum at 220 K. This could be attributed to (1) the carrier redistribution and the novel sandwiched MQWs' high carrier trapping capability; (2) the intrinsic emission property of the MQWs enhanced by improvement of electron-hole overlap and reduction of quantum confined Stark effect (QCSE) and compositional fluctuation. TDPL under 405 nm laser excitation is also measured to support this view. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Application of layered finite elements in the numerical analysis of laminated composite and sandwich structures with delaminations

    Directory of Open Access Journals (Sweden)

    Vuksanović Đorđe

    2015-01-01

    Full Text Available Laminar composites are modern engineering materials widely used in the mechanical and civil engineering. In the paper, some recent advances in a numerical analysis of laminated composite and sandwich plates and shells of different shapes, with existing zones of partial delamination, are presented. The layered finite elements, based on the extended version of the Generalized Laminated Plate Theory of Reddy, are applied for the numerical solution of several structural problems. After the verification of the proposed model for intact structures using the existing data from the literature, the effects of the size and the position of embedded delamination zones on the structural response of laminated structures are investigated numerically by means of a variety of numerical applications.

  7. Fatigue Debond Growth in Sandwich Structures Loaded in Mixed Mode Bending (MMB)

    DEFF Research Database (Denmark)

    Quispitupa, Amilcar; Berggreen, Christian; Carlsson, Leif A.

    2008-01-01

    the fracture toughness of the debonded sandwich specimens at different mixed mode loadings. The mixed mode ratio (mode I to mode II) was controlled by changing the lever arm distance of the MMB test rig. Compliance technique and visual inspection was employed to measure the crack length during fatigue. Fatigue...... tests were performed at 90% of the static fracture toughness at a loading ratio of R=0.1. Fatigue results revealed higher debond crack growth rates when the lever arm distance was increased. For some specimens, the crack propagated just below the face/core interface in the foam core and for others...... the crack kinked into the face sheet....

  8. Effects of Structural Damage on Dynamic Behavior at Sandwich Composite Beams - Part I-Theoretical Approach

    Directory of Open Access Journals (Sweden)

    Tufoi Marius

    2014-07-01

    Full Text Available This paper series presents an analysis regarding the dynamics of sandwich composite beams, embedded at one end, in order to highlight the effect of geometrical and material discontinuities upon the natural frequencies. In first part (Part I, analysis was performed with EulerBernoulli analytical method for determining the vibration modes and in second part (Part II, analysis was performed with numerical simulation in SolidWorks software for a five-layer composite. In the last section of the paper, an example is shown regarding how to interpret the obtained results.

  9. Scalable Synthesis of Freestanding Sandwich-structured Graphene/Polyaniline/Graphene Nanocomposite Paper for Flexible All-Solid-State Supercapacitor

    Science.gov (United States)

    Xiao, Fei; Yang, Shengxiong; Zhang, Zheye; Liu, Hongfang; Xiao, Junwu; Wan, Lian; Luo, Jun; Wang, Shuai; Liu, Yunqi

    2015-03-01

    We reported a scalable and modular method to prepare a new type of sandwich-structured graphene-based nanohybrid paper and explore its practical application as high-performance electrode in flexible supercapacitor. The freestanding and flexible graphene paper was firstly fabricated by highly reproducible printing technique and bubbling delamination method, by which the area and thickness of the graphene paper can be freely adjusted in a wide range. The as-prepared graphene paper possesses a collection of unique properties of highly electrical conductivity (340 S cm-1), light weight (1 mg cm-2) and excellent mechanical properties. In order to improve its supercapacitive properties, we have prepared a unique sandwich-structured graphene/polyaniline/graphene paper by in situ electropolymerization of porous polyaniline nanomaterials on graphene paper, followed by wrapping an ultrathin graphene layer on its surface. This unique design strategy not only circumvents the low energy storage capacity resulting from the double-layer capacitor of graphene paper, but also enhances the rate performance and cycling stability of porous polyaniline. The as-obtained all-solid-state symmetric supercapacitor exhibits high energy density, high power density, excellent cycling stability and exceptional mechanical flexibility, demonstrative of its extensive potential applications for flexible energy-related devices and wearable electronics.

  10. Seismic Evaluation of Structural Insulated Panels in Comparison with Wood-Frame Panels

    Directory of Open Access Journals (Sweden)

    Stefanie Terentiuk

    2014-07-01

    Full Text Available Structural Insulated Panel (SIP wall systems have been used in residential and light commercial buildings for the past sixty years. Lack of sufficient published research on racking load performance and limited understanding of the influence of fastener types on seismic response has been a deterrent in widespread use of the wall system in seismically active areas. This paper presents the results of a study involving a total of twenty one 2.4 m × 2.4 m shear walls tested under monotonic and cyclic loading. Four different 114 mm thick SIP panel configurations and one traditional wood frame wall were tested under monotonic loading according to ASTM E 564-06; and thirteen 114 mm thick SIP panels and three wood frame walls were tested under the CUREE loading protocol according to ASTM E 2126-11. Parameters such as fastener type; spline design; hold-down anchor location; and sheathing bearing were adjusted throughout the testing in order to determine their effects on the SIP’s performance. Performance parameters such as peak load and displacement; energy dissipation; allowable drift load capacity and seismic compatibility were determined for all of the specimens. Such parameters were then used to demonstrate the SIP walls’ compatibility with the wood frame walls and to determine the efficiency of the different SIP wall configuration and spline systems employed.

  11. Amino Acid Distribution Rules Predict Protein Fold: Protein Grammar for Beta-Strand Sandwich-Like Structures

    Science.gov (United States)

    Kister, Alexander

    2015-01-01

    We present an alternative approach to protein 3D folding prediction based on determination of rules that specify distribution of “favorable” residues, that are mainly responsible for a given fold formation, and “unfavorable” residues, that are incompatible with that fold, in polypeptide sequences. The process of determining favorable and unfavorable residues is iterative. The starting assumptions are based on the general principles of protein structure formation as well as structural features peculiar to a protein fold under investigation. The initial assumptions are tested one-by-one for a set of all known proteins with a given structure. The assumption is accepted as a “rule of amino acid distribution” for the protein fold if it holds true for all, or near all, structures. If the assumption is not accepted as a rule, it can be modified to better fit the data and then tested again in the next step of the iterative search algorithm, or rejected. We determined the set of amino acid distribution rules for a large group of beta sandwich-like proteins characterized by a specific arrangement of strands in two beta sheets. It was shown that this set of rules is highly sensitive (~90%) and very specific (~99%) for identifying sequences of proteins with specified beta sandwich fold structure. The advantage of the proposed approach is that it does not require that query proteins have a high degree of homology to proteins with known structure. So long as the query protein satisfies residue distribution rules, it can be confidently assigned to its respective protein fold. Another advantage of our approach is that it allows for a better understanding of which residues play an essential role in protein fold formation. It may, therefore, facilitate rational protein engineering design. PMID:25625198

  12. Influence of the inter-layer adhesion on the structural strength of sandwich pipes; Influencia da adesao entre camadas na resistencia estrutural de dutos sanduiche

    Energy Technology Data Exchange (ETDEWEB)

    Castello, Xavier; Estefen, Segen [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Oceanica

    2005-07-01

    Sandwich pipes composed of two steel layers separated by a polypropylene annulus can be used for the transport of oil and gas in deep waters, combining high structural resistance with thermal insulation in order to prevent blockage by paraffin and hydrates. In this work, sandwich pipes with typical inner diameters of those employed in the offshore production are analyzed numerically regarding to the influence of the inter-layer adhesion of steel pipes and polymer on the limit strength under external pressure and longitudinal bending as well as the bending and straightening process representative of the reeling installation method. The numerical model incorporates geometric and material non-linearity, which had been based on previous works of the authors. Tests of specimens under tension and segments of sandwich pipes are carried through to evaluate the maximum shear stresses of the interfaces metal-polymer. The adhesion is modeled by contact adopting a maximum shear stress value to allow the relative displacement between the layers. It was observed that the structural resistance of the sandwich pipe is strongly dependent on the shear stress acting at the interface, occurring the collapse of the pipe when the maximum shear stress is reached. The results obtained are analyzed to determine the minimum shear strength at the union which provides adequate structural resistance for the sandwich pipe under representative conditions of the installation and operation loading phases. (author)

  13. Comparison of various decentralised structural and cavity feedback control strategies for transmitted noise reduction through a double panel structure

    NARCIS (Netherlands)

    Ho, J.H.; Berkhoff, A.P.

    2014-01-01

    This paper compares various decentralised control strategies, including structural and acoustic actuator-sensor configuration designs, to reduce noise transmission through a double panel structure. The comparison is based on identical control stability indexes. The double panel structure consists of

  14. Comparison of various decentralised structural and cavity feedback control strategies for transmitted noise reduction through a double panel structure

    NARCIS (Netherlands)

    Ho, J.; Berkhoff, Arthur P.

    This paper compares various decentralised control strategies, including structural and acoustic actuator–sensor configuration designs, to reduce noise transmission through a double panel structure. The comparison is based on identical control stability indexes. The double panel structure consists of

  15. Solution-Processed rGO/AgNPs/rGO Sandwich Structure as a Hole Extraction Layer for Polymer Solar Cells

    Directory of Open Access Journals (Sweden)

    Quang Trung Tran

    2015-01-01

    Full Text Available We found that inserting silver nanoparticles (AgNPs between two layers of reduced grapheme oxide (rGO has an effect on tailoring the work function of rGO. The utilization of rGO/AgNPs/rGO sandwich structure as the hole extraction layer in polymer solar cells is demonstrated. Solution-processable fabrication of this sandwich structure at the ITO/active layer interface facilitates the extraction of hole from active layer into ITO anode because of lowering the barrier level alignment at the interface. It results in an improvement of the short circuit current density and the overall photovoltaic performance.

  16. Solution-Processed rGO/AgNPs/rGO Sandwich Structure as a Hole Extraction Layer for Polymer Solar Cells

    OpenAIRE

    Quang Trung Tran; Hoang Thi Thu; Vinh Son Tran; Tran Viet Cuong; Chang-Hee Hong

    2015-01-01

    We found that inserting silver nanoparticles (AgNPs) between two layers of reduced grapheme oxide (rGO) has an effect on tailoring the work function of rGO. The utilization of rGO/AgNPs/rGO sandwich structure as the hole extraction layer in polymer solar cells is demonstrated. Solution-processable fabrication of this sandwich structure at the ITO/active layer interface facilitates the extraction of hole from active layer into ITO anode because of lowering the barrier level alignment at the in...

  17. Piezoelectric anisotropy and energy-harvesting characteristics of novel sandwich layer BaTiO3 structures

    Science.gov (United States)

    Roscow, James I.; Topolov, Vitaly Yu; Taylor, John T.; Bowen, Christopher R.

    2017-10-01

    This paper presents a detailed modelling and experimental study of the piezoelectric and dielectric properties of novel ferroelectric sandwich layer BaTiO3 structures that consist of an inner porous layer and dense outer layers. The dependencies of the piezoelectric coefficients {d}3j* and dielectric permittivity {\\varepsilon }33* σ of the sandwich structure on the bulk relative density α are analysed by taking into account an inner layer with a porosity volume fraction of 0.5-0.6. The observed changes in {d}3j* and {\\varepsilon }33* σ are interpreted within the framework of a model of a laminar structure whereby the electromechanical interaction of the inner porous layer and outer dense layers have an important role in determining the effective properties of the system. The porous layer is represented as a piezocomposite with a 1-3-0 connectivity pattern, and the composite is considered as a system of long poled ceramic rods with 1-3 connectivity which are surrounded by an unpoled ceramic matrix that contains a system of oblate air pores (3-0 connectivity). The outer monolithic is considered as a dense poled ceramic, however its electromechanical properties differ from those of the ceramic rods in the porous layer due to different levels of mobility of 90° domain walls in ceramic grains. A large anisotropy of {d}3j* at α = 0.64-0.86 is achieved due to the difference in the properties of the porous and monolithic layers and the presence of highly oblate air pores. As a consequence, high energy-harvesting figures of merit {d}3j* {g}3j* are achieved that obey the condition {d}33* {g}33* /({d}31* {g}31* )˜ {10}2 at {d}33* {g}33* ˜ {10}-12 {{{Pa}}}-1, and values of the hydrostatic piezoelectric coefficients {d}h* ≈ 100 {{pC}} {{{N}}}-1 and {g}h* ≈ 20 {{mV}} {{m}} {{{N}}}-1 are achieved at α= 0.64-0.70. The studied BaTiO3-based sandwich structures has advantages over highly anisotropic PbTiO3-type ceramics as a result of the higher piezoelectric activity

  18. Synthesis of rGO/PS compound with sandwich structure on Ni foam as binder-free electrode for supercapacitor

    Science.gov (United States)

    Luo, Guangsheng; Huang, Haifu; Cheng, Zhenzhi; Lei, Chenglong; Wu, Xiaoshan; Tang, Shaolong; Du, Youwei

    Here, we demonstrate the design of a binder-free reduced graphene oxide (rGO) and polystyrene colloidal microsphere (PS) compound with rGO/PS/rGO sandwich structure and application for supercapacitors electrode. rGO and PS are alternately deposited into 3D Ni foam by a simple layer-by-layer assembly based on dip-coating. The interlayer space of rGO film expanded by PS microsphere and 3D structure of compound electrode can effectively shorten diffusion pathways of ions and accelerate the transport of ions into graphene sheets. The resulting rGO/PS compound electrode exhibits a high specific capacitance with 164.7F g-1, and outstanding rate capability. It is found that the specific capacitance is dependent on the number of rGO film layers in rGO/PS compound electrode.

  19. Self-healing of sandwich structures with a grid stiffened shape memory polymer syntactic foam core

    Science.gov (United States)

    John, Manu; Li, Guoqiang

    2010-07-01

    In this paper, a new sandwich with an orthogrid stiffened shape memory polymer (SMP) based syntactic foam core was proposed, fabricated, programmed, impacted, healed (sealed), and compression tested, for the purposes of healing impact damage repeatedly and almost autonomously. Two prestrain levels (3% and 20%), two impact energy levels (30.0 and 53.3 J), and two recovery (healing) conditions (2D confined and 3D confined) were employed in this paper. Up to seven impact-healing cycles were conducted. Macroscopic and microscopic damage-healing observation and analysis were implemented. Residual strength was evaluated using an anti-buckling compression test fixture. It was found that the healing efficiency was over 100% for almost all the impact-healing cycles; programming using 20% prestrain led to higher residual strength than that with 3% prestrain; 3D confined recovery resulted in higher residual strength than 2D confined recovery; and as the impact energy increased, the healing efficiency slightly decreased.

  20. Sandwich heterostructures of antimony trioxide and bismuth trioxide films: Structural, morphological and optical analysis

    Science.gov (United States)

    Condurache-Bota, Simona; Praisler, Mirela; Gavrila, Raluca; Tigau, Nicolae

    2017-01-01

    Thin film heterostructures can be advantageous since they either exhibit novel or a combination of the properties of their components. Here we propose sandwich-type of heterostructures made of antimony trioxide and bismuth trioxide thin films, which were deposited on glass substrates by thermal vacuum deposition at three substrate temperatures, 50° Celsius apart. Their morphology and optical properties are studied as compared to the corresponding monolayers. It was found that even small substrate temperature changes strongly influence their morphology, increasing their roughness, while the optical transmittance shows a slight decrease as compared with the individual layers. The corresponding absorption coefficient exhibits intermediate values as compared to the component oxides, while the energy bandgaps for the indirect allowed transitions move towards the Infrared when overlapping the antimony and bismuth trioxides.

  1. Ab initio study of structural and magnetic properties of TM(n)(ferrocene)(n+1) (TM = Sc, Ti, V, Mn) sandwich clusters and nanowires (n = infinity).

    Science.gov (United States)

    Zhang, Xiuyun; Wang, Jinlan; Gao, Yi; Zeng, Xiao Cheng

    2009-03-24

    Structural and magnetic properties of multidecker sandwich clusters TM(n)(ferrocene)(n+1) [TM = V, Ti, Sc, Mn, ferrocene=FeCp(2), n = 1-3] and corresponding one-dimensional sandwich nanowires (n = infinity) are studied by means of gradient-corrected density functional theory. The TM(n)(FeCp(2))(n+1) clusters are highly stable polyferrocene-like sandwich structures due to strong Fe-Cp interaction. The total magnetic moment of TM(n)(FeCp(2))(n+1) (TM = V, Ti, Mn) increases linearly with the size n. More strikingly, Ti(n)(FeCp(2))(n+1) and V(n)(FeCp(2))(n+1) (n = 1-3) exhibit high magnetic moments 4, 8, 12 mu(B) and 1, 6, 11 mu(B), respectively. In contrast, Sc(n)(FeCp(2))(n+1) clusters are paramagnetic. The [TM(FeCp(2))](infinity) sandwich nanowires are ferromagnetic semiconductors whose band gap is 0.361, 0.506, 0.51, and 1.310 eV, respectively, for TM = Ti, Sc, V, and Mn. Among the four sandwich nanowires, [V(FeCp(2))](infinity) nanowire possesses the highest magnetic moment (5 mu(B)) per unit cell.

  2. Improved fatigue performance for wood-based structural panels using slot and tab construction

    Science.gov (United States)

    Jinghao Li; John F. Hunt; Shaoqin Gong; Zhiyong Cai

    2016-01-01

    This paper presents static and fatigue bending behavior for a wood-based structural panel having a slot and tab (S/T) construction technique. Comparisons were made with similarly fabricated panels without the S/T construction technique. Experimental results showed that both types of panels had similar bending properties in the static tests. However, the panels with S/T...

  3. Combined Compression and Shear Structural Evaluation of Stiffened Panels Fabricated Using Electron Beam Freeform Fabrication

    OpenAIRE

    Nelson, Erik Walter

    2008-01-01

    Unitized aircraft structures have the potential to be more efficient than current aircraft structures. The Electron Beam Freeform Fabrication (EBF3) process can be used to manufacture unitized aircraft structures. The structural efficiency of blade stiffened panels made with EBF3 was compared to panels made by integrally machining from thick plate. The panels were tested under two load cases in a combined compression-shear load test fixture. One load case tested the panels' responses to a...

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

    Science.gov (United States)

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

    2006-01-01

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

  5. A Numerical Study on the Edgewise Compression Strength of Sandwich Structures with Facesheet-Core Disbonds

    Science.gov (United States)

    Bergan, Andrew C.

    2017-01-01

    Damage tolerant design approaches require determination of critical damage modes and flaw sizes in order to establish nondestructive evaluation detection requirements. A finite element model is developed to assess the effect of circular facesheet-core disbonds on the strength of sandwich specimens subjected to edgewise compressive loads for the purpose of predicting the critical flaw size for a variety of design parameters. Postbuckling analyses are conducted in which an initial imperfection is seeded using results from a linear buckling analysis. Both the virtual crack closure technique (VCCT) and cohesive elements are considered for modeling disbond growth. Predictions from analyses using the VCCT and analyses using cohesive elements are in good correlation. A series of parametric analyses are conducted to investigate the effect of core thickness and material, facesheet layup, facesheet-core interface properties, and curvature on the criticality of facesheet-core disbonds of various sizes. The results from these analyses provide a basis for determining the critical flaw size for facesheet-core disbonds subjected to edgewise compression loads and, therefore, nondestructive evaluation flaw detection requirements for this configuration.

  6. Self-assembly of 2D sandwich-structured MnFe{sub 2}O{sub 4}/graphene composites for high-performance lithium storage

    Energy Technology Data Exchange (ETDEWEB)

    Li, Songmei, E-mail: songmei_li@buaa.edu.cn; Wang, Bo; Li, Bin; Liu, Jianhua; Yu, Mei; Wu, Xiaoyu

    2015-01-15

    Highlights: • MFO/GN composites were synthesized by a facile in situ solvothermal approach. • The MFO microspheres are sandwiched between the graphene layers. • Each MFO microsphere is an interstitial cluster of nanoparticles. • The MFO/GN electrode exhibits an enhanced cyclability for Li-ion batteries anodes. - Abstract: In this study, two-dimensional (2D) sandwich-structured MnFe{sub 2}O{sub 4}/graphene (MFO/GN) composites are synthesized by a facile in situ solvothermal approach, using cetyltrimethylammonium bromide (CTAB) as cationic surfactant. As a consequence, the nanocomposites of MFO/GN self-assembled into a 2D sandwich structure, in which the interstitial cluster structure of microsphere-type MnFe{sub 2}O{sub 4} is sandwiched between the graphene layers. This special structure of the MFO/GN composites used as anodes for lithium-ion batteries will be favorable for the maximum accessible surface of electroactive materials, fast diffusion of lithium ions and migration of electron, and elastomeric space to accommodate volume changes during the discharge–charge processes. The as-synthesized MFO/GN composites deliver a high specific reversible capacity of 987.95 mA h g{sup −1} at a current density of 200 mA g{sup −1}, a good capacity retention of 69.27% after 80 cycles and excellent rate performance for lithium storage.

  7. Design considerations for HFQ® hot stamped aluminium structural panels

    Directory of Open Access Journals (Sweden)

    Foster Alistair

    2015-01-01

    Full Text Available HFQ is a deep drawing process for alloyed aluminium sheet that can be used to produce complex-stamped forms while maintaining the high-strength of 6xxx and 7xxx alloys. By adopting a strategy to design for HFQ at the platform level, designers can reduce part count (thereby reducing cost and weight, reduce gauge (thereby reducing weight, and improve part packaging. Two simple design examples are given to assist designers in evolving traditionally formed panel designs to HFQ formed solutions. Example features are used to illustrate the effect of geometry, thickness and strength on the final structural component.

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

    Science.gov (United States)

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

    2006-01-01

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

  9. Failure mode prediction for composite structural insulated panels with MgO board facings

    Science.gov (United States)

    Smakosz, Łukasz; Kreja, Ireneusz

    2018-01-01

    Sandwich panels are readily used in civil engineering due to their high strength to weight ratio and the ease and speed of assembly. The idea of a sandwich section is to combine thin and durable facings with a light-weight core and the choice of materials used allows obtaining the desired behaviour. Panels in consideration consist of MgO (magnesium oxide) board facings and expanded polystyrene core and are characterized by immunity to biological corrosion, a high thermal insulation and a relatively low impact on environment. Customizing the range of panels to meet market needs requires frequent size changes, leading to different failure modes, which are identified in a series of costly full-scale laboratory tests. A nonlinear numerical model was created with a use of a commercial ABAQUS code and a user-defined procedure, which is able to reproduce observed failure mechanisms; its parameters were established on the basis of small-scale tests and numerical experiments. The model was validated by a comparison with the results of the full-scale bending and compression tests. The results obtained were in satisfactory agreement with the test data.

  10. Structuring User Involvement in Panel-Based Living Labs

    Directory of Open Access Journals (Sweden)

    Lieven De Marez

    2012-09-01

    Full Text Available A shift towards open innovation approaches with systematic user involvement has occurred within media and ICT. One of the emerging frameworks structuring these initiatives is the "living lab" approach. Despite the growing evidence of the beneficial nature of customer involvement in product development, research into specific user characteristics for innovation is still scarce, particularly in living labs, with the notable exception of literature on lead users. Especially within the context of living labs for ICT and media innovation, an application of the lead-user framework looks promising as a way to structure and facilitate user involvement. This article is based on the experiences of three Flemish living lab initiatives with a panel-based approach and provides a customer characteristics framework that guides user involvement in living labs.

  11. Comportamiento de paneles de bambú guadua laminado ante cargas paralelas al plano The structural behaviour of laminated-guadua panels under parallel plane loads

    Directory of Open Access Journals (Sweden)

    Takeuchi Tam Caori Patricia

    2012-08-01

    Full Text Available

    Como un primer paso en el estudio del comportamiento ante cargas sísmicas de pórticos de bambú guadua laminados con paneles del mismo material, el Grupo de Investigación “Análisis, Diseño y Materiales, GIES”, de la Universidad Nacional de Colombia, ensayó dos tipos de paneles elaborados con bambú Guadua angustifolia Kunth y poli (vinil acetato, PVA: los paneles tipo 1 de sección transversal maciza y los paneles tipo 2 de sección transversal tipo sándwich.
    Se consideraron tres alturas para cada tipo de panel y se ensayaron diez réplicas por altura y por tipo, para un total de sesenta ensayos.
    Para cada uno de los paneles ensayados se realizó una curva carga-desplazamiento. Los paneles tipo 1, con altura de 0,34 m y 0,63 m, mostraron un comportamiento elástico inicial seguido de un comportamiento inelástico, mientras que los paneles tipo 1 y 2 de 0,98 m de altura revelaron un comportamiento casi totalmente elástico hasta la falla. Todos los paneles sufrieron aplastamiento en la base; sin embargo, el principal mecanismo de falla fue el alabeo.
    The Universidad Nacional de Colombia "Analysis, Design and Materials - GIES" research group tested two types of panels made from Guadua angustifolia Kunth and poly vinyl acetate (PVA as a first step in studying the behaviour of laminated guadua frames having panels of the same material under seismic load: type 1 panels had a solid cross-section and type 2 panels a sandwich cross-section.
    Each type of panel had three different heights and 10 replicates were tested for each type and height (60 trials in total.
    Each panel’s load compared to displacement curve was found; 0.34m and 0.63m type1 panels had initial elastic behaviour followed by inelastic behaviour while 0.98 m panels made of both types had an almost completely elastic behaviour until failure. All panels became crushed at their base; however, the main failure mechanism was

  12. Thermally-Induced Structural Disturbances of Rigid Panel Solar Arrays

    Science.gov (United States)

    Johnston, John D.; Thornton, Earl A.

    1997-01-01

    The performance of a significant number of spacecraft has been impacted negatively by attitude disturbances resulting from thermally-induced motions of flexible structures. Recent examples of spacecraft affected by these disturbances include the Hubble Space Telescope (HST) and the Upper Atmosphere Research Satellite (UARS). Thermally-induced structural disturbances occur as the result of rapid changes in thermal loading typically initiated as a satellite exits or enters the Earth's shadow. Temperature differences in flexible appendages give rise to structural deformations, which in turn result in disturbance torques reacting back on the spacecraft. Structures which have proven susceptible to these disturbances include deployable booms and solar arrays. This paper investigates disturbances resulting from thermally-induced deformations of rigid panel solar arrays. An analytical model for the thermal-structural response of the solar array and the corresponding disturbance torque are presented. The effect of these disturbances on the attitude dynamics of a simple spacecraft is then investigated using a coupled system of governing equations which includes the effects of thermally-induced deformations. Numerical results demonstrate the effect of varying solar array geometry on the dynamic response of the system.

  13. Absence of coupled thermal interfaces in Al2O3/Ni/Al2O3 sandwich structure

    Science.gov (United States)

    Li, Xiangyu; Park, Wonjun; Chen, Yong P.; Ruan, Xiulin

    2017-10-01

    Sandwich structures of aluminum oxide, nickel, and aluminum oxide films are fabricated by atomic layer deposition to study thermal interfacial resistance between a metal and a dielectric material and the interfacial coupling effect across a thin metal layer. Thermal resistance of a thin nickel layer as well as two interfaces is measured using the 3ω method. Experimental results show interfacial resistance between nickel and aluminum oxide to be 6.8 ×10-3mm2 K /W at 300 K, with a weak dependence on the metal thickness and temperature. A two-temperature model and a detailed diffuse mismatch model have been used to estimate interfacial resistance theoretically, and the results agree reasonably well with experiments. Estimations from the two temperature model indicate that in the overall thermal interfacial resistance, the phonon-phonon interfacial resistance dominates over the resistance due to the electron-phonon coupling effect and inside the metal layer. Also, the phonon-phonon interfacial resistance does not vary as the metal layer thickness decreases below the electron-phonon cooling length, indicating that the two adjacent interfaces are not thermally coupled.

  14. Multiscale Fatigue Life Prediction for Composite Panels

    Science.gov (United States)

    Bednarcyk, Brett A.; Yarrington, Phillip W.; Arnold, Steven M.

    2012-01-01

    Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer s coupling with NASA s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach this damage increment is calculated. In this way, the effect of stress redistribution due to damage-induced stiffness change is captured, but the fatigue simulations remain computationally efficient. The model is compared to experimental fatigue life data for two composite facesheet/foam core sandwich panels, demonstrating very good agreement.

  15. Application of Shearography Techniques for Vibration Characterization and Damage Detection in Sandwich Structures

    National Research Council Canada - National Science Library

    Vollen, Marianne W; Vikhagen, Eiolf; Wang, Gunnar; Jensen, Alf E; Haugland, Svein J

    2005-01-01

    The paper presents a new Electronic Shearography (ES) system for Structural Health Monitoring and damage detection, where a huge step in sensitivity has been accomplished compared to earlier shearography systems...

  16. Influence of material non-linearity on the thermo-mechanical response of polymer foam cored sandwich structures - FE modelling and preliminary experiemntal results

    DEFF Research Database (Denmark)

    Palleti, Hara Naga Krishna Teja; Thomsen, Ole Thybo; Fruehmann, Richard.K

    to the model. The full stress-strain curves up to failure will be considered for the polymer foams at different temperatures in order to study the plasticity influence of polymer foam on the sandwich structures in detail. Due to stiff face sheets resting on the soft polymer core and the ratio of the stiffness...... of the core to polymer foam core increases with the increase temperature the problem suffers from the inherent ill-conditionality. Along with the inherent ill-conditioning, there is geometric non linearity and the material non linearity which makes the problem difficult to solve due to the convergence issues....... Finally the paper will be presenting the effect of material nonlinearity accompanied with geometric non linearity on the polymer foam cored sandwich structures subjected to thermo-mechanical load...

  17. Experimental investigation on the dynamic response of clamped corrugated sandwich plates subjected to underwater impulsive loadings

    Science.gov (United States)

    Huang, Wei; Zhang, Wei; Li, Dacheng; Hypervelocity Impact Research Center Team

    2015-06-01

    Corrugated sandwich plates are widely used in marine industry because such plates have high strength-to-weight ratios and blast resistance. The laboratory-scaled fluid-structure interaction experiments are performed to demonstrate the shock resistance of solid monolithic plates and corrugated sandwich plates by quantifying the permanent transverse deflection at mid-span of the plates as a function of impulsive loadings per areal mass. Sandwich structures with 6mm-thick and 10mm-thick 3003 aluminum corrugated core and 5A06 face sheets are compared with the 5A06 solid monolithic plates in this paper. The dynamic deformation of plates are captured with the the 3D digital speckle correlation method (DIC). The results affirm that sandwich structures show a 30% reduction in the maximum plate deflection compare with a monolithic plate of identical mass per unit area, and the peak value of deflection effectively reduced by increasing the thickness core. The failure modes of sandwich plates consists of core crushing, imprinting, stretch tearing of face sheets, bending and permanent deformation of entire structure with the increasing impulsive loads, and the failure mechanisms are analyzed with the postmortem panels and dynamic deflection history captured by cameras. National Natural Science Foundation of China (NO.: 11372088).

  18. Circuit models for Salisbury screens made from unidirectional carbon fiber composite sandwich structures

    Science.gov (United States)

    Riley, Elliot J.; Lenzing, Erik H.; Narayanan, Ram M.

    2016-05-01

    Carbon fiber composite materials have many useful structural material properties. The electromagnetic perfor- mance of these materials is of great interest for future applications. The work presented in this paper deals with the construction of Salisbury screen microwave absorbers made from unidirectional carbon fiber composite sand- wich structures. Specifically, absorbers centered at 7.25 GHz and 12.56 GHz are investigated. Circuit models are created to match the measured performance of the carbon fiber Salisbury screens using a genetic algorithm to extract lumped element circuit values. The screens presented in this paper utilize unidirectional carbon fiber sheets in place of the resistive sheet utilized in the classic Salisbury screen. The theory, models, prototypes, and measurements of these absorbers are discussed.

  19. Standard Test Method for Water Absorption of Core Materials for Structural Sandwich Constructions

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2001-01-01

    1.1 This test method covers the determination of the relative amount of water absorption by various types of structural core materials when immersed or in a high relative humidity environment. This test method is intended to apply to only structural core materials; honeycomb, foam, and balsa wood. 1.2 The values stated in SI units are to be regarded as the standard. The inch-pound units given may be approximate. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  20. Effects of Structural Damage on Dynamic Behavior at Sandwich Composite Beams – Part II- FEM Analysis

    Directory of Open Access Journals (Sweden)

    Marius Tufoi

    2014-07-01

    Full Text Available This paper presents results obtained by modal analysis on composite beam like structures in healthy and damaged state. The aim is to obtain damage “signatures” for all possible damage scenarios and to use these data to assess transversal cracks based on vibration techniques, by involving natural frequency shifts. The analysis was performed in SolidWorks software for a five-layer composite, 20 vibration modes being obtained by numerical simulation.

  1. A study on an efficient prediction of welding deformation for T-joint laser welding of sandwich panel Part II: Proposal of a method to use shell element model

    Directory of Open Access Journals (Sweden)

    Jae Woong Kim

    2014-06-01

    Full Text Available I-core sandwich panel that has been used more widely is assembled using high power CO2 laser welding. Kim et al. (2013 proposed a circular cone type heat source model for the T-joint laser welding between face plate and core. It can cover the negative defocus which is commonly adopted in T-joint laser welding to provide deeper penetration. In part I, a volumetric heat source model is proposed and it is verified thorough a comparison of melting zone on the cross section with experiment results. The proposed model can be used for heat transfer analysis and thermal elasto-plastic analysis to predict welding deformation that occurs during laser welding. In terms of computational time, since the thermal elasto-plastic analysis using 3D solid elements is quite time consuming, shell element model with multi-layers have been employed instead. However, the conventional layered approach is not appropriate for the application of heat load at T-Joint. This paper, Part II, suggests a new method to arrange different number of layers for face plate and core in order to impose heat load only to the face plate.

  2. A study on an efficient prediction of welding deformation for T-joint laser welding of sandwich panel Part II : Proposal of a method to use shell element model

    Directory of Open Access Journals (Sweden)

    Kim Jae Woong

    2014-06-01

    Full Text Available I-core sandwich panel that has been used more widely is assembled using high power CO₂laser welding. Kim et al. (2013 proposed a circular cone type heat source model for the T-joint laser welding between face plate and core. It can cover the negative defocus which is commonly adopted in T-joint laser welding to provide deeper penetration. In part I, a volumetric heat source model is proposed and it is verified thorough a comparison of melting zone on the cross section with experiment results. The proposed model can be used for heat transfer analysis and thermal elasto-plastic analysis to predict welding deformation that occurs during laser welding. In terms of computational time, since the thermal elasto-plastic analysis using 3D solid elements is quite time consuming, shell element model with multi-layers have been employed instead. However, the conventional layered approach is not appropriate for the application of heat load at T-Joint. This paper, Part II, suggests a new method to arrange different number of layers for face plate and core in order to impose heat load only to the face plate.

  3. Finite Element Approach for Analyses of Flanking Noise Transmission within Lightweight Panel Structure

    DEFF Research Database (Denmark)

    Domadiya, Parthkumar Gandalal; Dickow, Kristoffer Ahrens; Andersen, Lars

    2011-01-01

    This paper concerns the analysis of noise transmission in a lightweight panel structure. The analysis is based on Finite Element Analysis (FEA) employing solid elements for the structure. The analysis focuses on flanking noise transmission in panel structures of finite size. A parametric study...... and different designs of the ribs regarding the energy contained within the panel strip. The paper presents an analysis of vibrational energy transmission for an isotropic periodic panel strip excited by a concentrated force. The computations are carried out in frequency domain in the range below 2 kHz....

  4. Dimers of nineteen-electron sandwich compounds: Crystal and electronic structures, and comparison of reducing strengths

    KAUST Repository

    Mohapatra, Swagat Kumar

    2014-10-03

    The dimers of some Group 8 metal cyclopentadienyl/ arene complexes and Group 9 metallocenes can be handled in air, yet are strongly reducing, making them useful n-dopants in organic electronics. In this work, the Xray molecular structures are shown to resemble those of Group 8 metal cyclopentadienyl/pentadienyl or Group 9 metal cyclopentadienyl/diene model compounds. Compared to those of the model compounds, the DFT HOMOs of the dimers are significantly destabilized by interactions between the metal and the central C-C σ-bonding orbital, accounting for the facile oxidation of the dimers. The lengths of these C-C bonds (X-ray or DFT) do not correlate with DFT dissociation energies, the latter depending strongly on the monomer stabilities. Ru and Ir monomers are more reducing than their Fe and Rh analogues, but the corresponding dimers also exhibit much higher dissociation energies, so the estimated monomer cation/neutral dimer potentials are, with the exception of that of [RhCp2]2, rather similar (-1.97 to-2.15 V vs. FeCp2 +/0 in THF). The consequences of the variations in bond strength and redox potentials for the reactivity of the dimers are discussed.

  5. Acoustically Tailored Composite Rotorcraft Fuselage Panels

    Science.gov (United States)

    Hambric, Stephen; Shepherd, Micah; Koudela, Kevin; Wess, Denis; Snider, Royce; May, Carl; Kendrick, Phil; Lee, Edward; Cai, Liang-Wu

    2015-01-01

    A rotorcraft roof sandwich panel has been redesigned to optimize sound power transmission loss (TL) and minimize structure-borne sound for frequencies between 1 and 4 kHz where gear meshing noise from the transmission has the most impact on speech intelligibility. The roof section, framed by a grid of ribs, was originally constructed of a single honeycomb core/composite face sheet panel. The original panel has coincidence frequencies near 700 Hz, leading to poor TL across the frequency range of 1 to 4 kHz. To quiet the panel, the cross section was split into two thinner sandwich subpanels separated by an air gap. The air gap was sized to target the fundamental mass-spring-mass resonance of the double panel system to less than 500 Hz. The panels were designed to withstand structural loading from normal rotorcraft operation, as well as 'man-on-the-roof' static loads experienced during maintenance operations. Thin layers of VHB 9469 viscoelastomer from 3M were also included in the face sheet ply layups, increasing panel damping loss factors from about 0.01 to 0.05. Measurements in the NASA SALT facility show the optimized panel provides 6-11 dB of acoustic transmission loss improvement, and 6-15 dB of structure-borne sound reduction at critical rotorcraft transmission tonal frequencies. Analytic panel TL theory simulates the measured performance quite well. Detailed finite element/boundary element modeling of the baseline panel simulates TL slightly more accurately, and also simulates structure-borne sound well.

  6. Elimination of photon quenching by a transition layer to fabricate a quenching-shield sandwich structure for 800 nm excited upconversion luminescence of Nd3+-sensitized nanoparticles.

    Science.gov (United States)

    Zhong, Yeteng; Tian, Gan; Gu, Zhanjun; Yang, Yijun; Gu, Lin; Zhao, Yuliang; Ma, Ying; Yao, Jiannian

    2014-05-01

    Nd3+-sensitized quenching-shield sandwich-structured upconversion nanoparticles are reported, which exhibit highly efficient upconversion photoluminescence under excitation by an 800 nm continuous-wave laser. The transition-layer structure is essential to bridge energy transfer from the sensitizer to the activator and simultaneously block energy back-transfer from the activator to the sensitizer. These 800 nm-excited upconversion nanoparticles are a key step toward the development of upconversion nanophosphors for biological applications. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Enhanced antibacterial activity of silver nanoparticles/halloysite nanotubes/graphene nanocomposites with sandwich-like structure.

    Science.gov (United States)

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

    2014-04-11

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

  8. Análisis de ciclo de vida simplificado aplicado a viviendas de paneles SIP (structural insulated panels

    Directory of Open Access Journals (Sweden)

    Juan Pablo Cárdenas

    2015-04-01

    Full Text Available A medida que los asuntos ambientales se vuelven más importantes, las construcciones se han enfocado en su eficiencia energética y la energía necesaria para construir y producir los materiales. Esta investigación muestra un estudio de Análisis de Ciclo de Vida simplificado de energía operacional y energía contenida de cuatro viviendas nuevas ubicadas en Temuco, Chile, estructuradas con paneles SIP (Structural insulated panel para cuantificar la energía en cada etapa de este sistema de construcción. Para obtener la energía contenida, fueron utilizadas dos bases de datos internacionales para cuantificar la energía de cada material y se determinó la energía contenida en el proceso relacionado a la estructura de paneles SIP a través de mediciones en una compañía especializada en construcción de paneles SIP. Para la energía operacional, se llevaron a cabo modelos computacionales con el software Design Builder y se proyectó esta energía con una vida útil de 50 años. El análisis de la información obtenida muestra que la energía contenida por procesos de construcción representa cerca del 1.7% de la energía contenida y mientras que el total de energía contenida representa el 11% de la energía del ciclo de vida total de las viviendas, el remanente 89% representa la energía de operación. Por otro lado, observamos que las viviendas con paneles SIP generan cifras cercanas al 60% en ahorro en demanda energética, comparadas a las viviendas de mampostería estructural normalmente construidas en esta ciudad.

  9. Creep Behavior of Structural Insulated Panels (SIPS): Results from a Pilot Study

    Science.gov (United States)

    Dwight McDonald; Marshall Begel; C. Adam Senalik; Robert Ross; Thomas D. Skaggs; Borjen Yeh; Thomas Williamson

    2014-01-01

    Structural insulated panels (SIPs) have been recognized as construction materials in the International Residential Code (IRC) since 2009. Although most SIPs are used in wall applications, they can also be used as roof or floor panels that are subjected to long-term transverse loading, for which SIP creep performance may be critical in design. However, limited...

  10. Control source development for reduction of noise transmitted through a double panel structure

    NARCIS (Netherlands)

    Ho, J.

    2014-01-01

    A double panel structure, which consists of two panels with air in between, is widely adopted in many applications such as aerospace, automotive industries, and buildings due to its low sound transmission at high frequencies, low heat transmission, and low weight. Nevertheless, the resonance of the

  11. Structural behavior of SC panel subjected to impact loading using finite element analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyuk-Kee; Kim, Seung-Eock, E-mail: sekim@sejong.ac.kr

    2015-12-15

    Highlights: • Structural behavior of SC panel subjected to impact loading is evaluated using numerical analysis. • Sensitivity studies according to fracture energy and erosion value are performed. • Analysis results are compared with impact test for SC panel. - Abstract: After the terrorist attack on the World Trade Center using aircraft in New York City in 2001, safety assessments of nuclear power plant (NPP) structures subjected to impact loading have been actively performed. Since impact tests are possible for small-scale structures but not for full-scale structures, finite element (FE) analysis is necessary for a safety assessment of NPP structure. Analysis factors such as the material model of concrete and steel, strain rate effect, concrete fracture energy, and erosion value influence the analysis results. In this paper, the effect of the concrete fracture energy and the erosion in the material model of a steel-plate concrete (SC) panel subjected to the impact loading is evaluated using the commercial software LS-DYNA. The analysis results are compared with the impact test for an SC panel conducted in other research. A quarter model of an SC panel is adopted for impact analysis. The impact force–time history is applied on the SC panel. Sensitivity studies according to the fracture energy and the erosion value are performed in order to evaluate the structural behavior of SC panels.

  12. Sandwich or sweets?

    DEFF Research Database (Denmark)

    Kraus, Alexandra; Piqueras-Fiszman, Betina

    2016-01-01

    with the use of indirect measurements. However, literature results on the relationship between dynamic, motivational concepts (e.g., approach or avoidance tendencies) and evaluative concepts (e.g., positive or negative associations) remain inconclusive, possibly due to the use of different experimental...... manipulations and methodologies to operationalize these. Our aim with this study is to contribute to this line of research by developing a novel methodology that is based on structurally identical indirect measurement procedures. We measured explicit desire (motivation) and liking (evaluation) of two different...... foods (sandwich and sweets) on visual analogue scales, as well as implicit approach–avoidance tendencies and implicit positive–negative associations with two variants of the recoding-free Implicit Association Tests (IAT-RFs). At first, all participants (N = 108) unwrapped, smelled, and explicitly judged...

  13. The Testing Equipment to Study Heat Transfer through a Frame-Panel Enclosure Structure Fragment

    Directory of Open Access Journals (Sweden)

    Borzykh Vladimir

    2016-01-01

    Full Text Available Thermal properties of the panel - frame enclosure structures used for construction purposes in the city of Tyumen have been studied. The effect of filtration on the change in the thermal flow rate has been revealed.

  14. Corrosion Mechanisms in Brazed Al-Base Alloy Sandwich Structures as a Function of Braze Alloy and Process Variables

    Science.gov (United States)

    2013-02-01

    Welding , Brazing, and Soldering (ASM International: Materials Park, Ohio, 1993) p. 937. 3. A.K. Bhattamishra and K. Lai, "Microstructural studies on the...TCT6) condition, c) UNS A96061 T6 + UNS A94047 foil wedge. 47 ^ mtsst k\\ ’J%jry~z & ■^ KC t ^\\T iH ^^ >*^ .CH\\ WBSSS^SK ;s * iW >flLr4w...at an International Conference for Braze or Weld Sandwich work One A.B. Campbell Award for best paper for an author under 35 years of age iv

  15. SIGNS The sandwich sign

    African Journals Online (AJOL)

    214. 5. Kunimasa K, Jo T, Takaiwa T, Ishida T. Thoracic sandwich sign. Intern Med 2011;50:2865. 6. Caceres J, Mata JM, Castaner E, Villanueva A. CT recognition of traumatic herniation of stomach: the sandwich sign. J Thorac Imaging 1995 ...

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

    Science.gov (United States)

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

    2001-01-01

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

  17. Structure and reactivities of rhenium and technetium bis-arene sandwich complexes [M(η(6)-arene)2]().

    Science.gov (United States)

    Meola, Giuseppe; Braband, Henrik; Jordi, Sara; Fox, Thomas; Blacque, Olivier; Spingler, Bernhard; Alberto, Roger

    2017-10-31

    Sandwich complexes are important building blocks in medicinal inorganic chemistry for group 6 and 8 elements but are almost unknown for the manganese triad. We present the syntheses and full characterization of the mixed-arene (99)Tc sandwich complexes [(99)Tc(η(6)-hmbz)(η(6)-C6H5-NH3)](PF6)2 and [(99)Tc(η(6)-hmbz)(η(6)-C6H5-Br)](PF6). Both comprise functionalities for conjugation to targeting molecules or for being included as substructures in pharmaceutically active lead compounds. Since η(6)-benzene ligands are too stably bound to be replaced with incoming ligands, we prepared naphthalene complexes [Re(η(6)-C6H6)(η(6)-napht)](+) and [Re(η(6)-napht)2](+). Their reactivities towards substitution are increased and one or both naphthalene ligands can be replaced with mono- or multi-dentate ligands. Combining the features of (99)Tc and Re may lead to a molecule-based theranostic approach.

  18. Development of dynamic loudspeakers modified as incident pressure sources for noise reduction in a double panel structure

    NARCIS (Netherlands)

    Ho, J.; Berkhoff, Arthur P.; Crocker, Malcolm J.; Pawelczyk, Marek; Paosawatyanyong, Boonchoat

    2013-01-01

    This paper presents a modified loudspeaker source for decentralized feedback cavity control in a double panel structure to reduce the noise transmission. The double panel structure con-sists of two panels with air in between and offers the advantages of low weight, low sound transmission at high

  19. Development of Dynamic Loudspeakers Modified as Incident Pressure Sources for Noise Reductiuon in a Double Panel Structure

    NARCIS (Netherlands)

    Ho, J.H.; Berkhoff, A.P.

    2013-01-01

    This paper presents a modified loudspeaker source for decentralized feedback cavity control in a double panel structure to reduce the noise transmission. The double panel structure con-sists of two panels with air in between and offers the advantages of low weight, low sound transmission at high

  20. Design of Pd/PANI/Pd sandwich-structured nanotube array catalysts with special shape effects and synergistic effects for ethanol electrooxidation.

    Science.gov (United States)

    Wang, An-Liang; Xu, Han; Feng, Jin-Xian; Ding, Liang-Xin; Tong, Ye-Xiang; Li, Gao-Ren

    2013-07-24

    Low cost, high activity, and long-term durability are the main requirements for commercializing fuel cell electrocatalysts. Despite tremendous efforts, developing non-Pt anode electrocatalysts with high activity and long-term durability at low cost remains a significant technical challenge. Here we report a new type of hybrid Pd/PANI/Pd sandwich-structured nanotube array (SNTA) to exploit shape effects and synergistic effects of Pd-PANI composites for the oxidation of small organic molecules for direct alcohol fuel cells. These synthesized Pd/PANI/Pd SNTAs exhibit significantly improved electrocatalytic activity and durability compared with Pd NTAs and commercial Pd/C catalysts. The unique SNTAs provide fast transport and short diffusion paths for electroactive species and high utilization rate of catalysts. Besides the merits of nanotube arrays, the improved electrocatalytic activity and durability are especially attributed to the special Pd/PANI/Pd sandwich-like nanostructures, which results in electron delocalization between Pd d orbitals and PANI π-conjugated ligands and in electron transfer from Pd to PANI.

  1. Threading structural model of the manganese-stabilizing protein PsbO reveals presence of two possible beta-sandwich domains.

    Science.gov (United States)

    Pazos, F; Heredia, P; Valencia, A; de las Rivas, J

    2001-12-01

    The manganese-stabilizing protein (PsbO) is an essential component of photosystem II (PSII) and is present in all oxyphotosynthetic organisms. PsbO allows correct water splitting and oxygen evolution by stabilizing the reactions driven by the manganese cluster. Despite its important role, its structure and detailed functional mechanism are still unknown. In this article we propose a structural model based on fold recognition and molecular modeling. This model has additional support from a study of the distribution of characteristics of the PsbO sequence family, such as the distribution of conserved, apolar, tree-determinants, and correlated positions. Our threading results consistently showed PsbO as an all-beta (beta) protein, with two homologous beta domains of approximately 120 amino acids linked by a flexible Proline-Glycine-Glycine (PGG) motif. These features are compatible with a general elongated and flexible architecture, in which the two domains form a sandwich-type structure with Greek key topology. The first domain is predicted to include 8 to 9 beta-strands, the second domain 6 to 7 beta-strands. An Ig-like beta-sandwich structure was selected as a template to build the 3-D model. The second domain has, between the strands, long-loops rich in Pro and Gly that are difficult to model. One of these long loops includes a highly conserved region (between P148 and P174) and a short alpha-helix (between E181 and N188)). These regions are characteristic parts of PsbO and show that the second domain is not so similar to the template. Overall, the model was able to account for much of the experimental data reported by several authors, and it would allow the detection of key residues and regions that are proposed in this article as essential for the structure and function of PsbO. Copyright 2001 Wiley-Liss, Inc.

  2. Mitigation of Flanking Noise in Double-Plate Panel Structures by Periodic Stiffening

    DEFF Research Database (Denmark)

    Domadiya, Parthkumar Gandalal; Dickow, Kristoffer Ahrens; Andersen, Lars

    2011-01-01

    The present analysis focuses on flanking noise transmission within a two-wall structure of finite size. The walls are lightweight panel structures, each consisting of two plates with internal ribs. A finite-element model is utilized, assuming that the studs are fully fixed to the plates. Further......, the air enclosed in the cavities within the structure is taken into consideration, whereas the external air has been disregarded. A fully coupled analysis is performed in which solid finite elements are adopted for the structure, whereas the acoustic medium within the panel is discretized into fluid...

  3. Ultra-multiband absorption enhancement of graphene in a metal-dielectric-graphene sandwich structure covering terahertz to mid-infrared regime.

    Science.gov (United States)

    Wang, Zongpeng; Hou, Yumin

    2017-08-07

    We investigate the absorption enhancement of an unstructured graphene sheet in a broad frequency range from terahertz (THz) to mid-infrared regime. Ultra-multiband graphene absorption enhancement is observed by integrating graphene in a metal-dielectric-graphene (MDG) sandwich structure for polarized waves. Multiple order Fabry-Perot (FP) resonances are demonstrated to be responsible for the multiband absorption. Furthermore, perfect absorption is realized by introducing the MDG structure on a metal reflector to suppress the transmission channel. In addition, the absorption peaks can be easily tuned by changing the doping level of graphene. This work may have potential for improving the performance of graphene based optoelectrical devices and can be regarded as a demonstration of a tunable broadband near-perfect metamaterial absorber.

  4. Experimental Study of the Bending Properties and Deformation Analysis of Web-Reinforced Composite Sandwich Floor Slabs with Four Simply Supported Edges

    Science.gov (United States)

    Qi, Yujun; Fang, Hai; Liu, Weiqing

    2016-01-01

    Web-reinforced composite sandwich panels exhibit good mechanical properties in one-way bending, but few studies have investigated their flexural behavior and deformation calculation methods under conditions of four simply supported edges. This paper studies the bending performance of and deformation calculation methods for two-way web-reinforced composite sandwich panels with different web spacing and heights. Polyurethane foam, two-way orthogonal glass-fiber woven cloth and unsaturated resin were used as raw materials in this study. Vacuum infusion molding was used to prepare an ordinary composite sandwich panel and 5 web-reinforced composite sandwich panels with different spacing and web heights. The panels were subjected to two-way panel bending tests with simple support for all four edges. The mechanical properties of these sandwich panels during the elastic stage were determined by applying uniformly distributed loads. The non-linear mechanical characteristics and failure modes were obtained under centrally concentrated loading. Finally, simulations of the sandwich panels, which used the mechanical model established herein, were used to deduce the formulae for the deflection deformation for this type of sandwich panel. The experimental results show that webs can significantly improve the limit bearing capacity and flexural rigidity of sandwich panels, with smaller web spacing producing a stronger effect. When the web spacing is 75 mm, the limit bearing capacity is 4.63 times that of an ordinary sandwich panel. The deduced deflection calculation formulae provide values that agree well with the measurements (maximum error panel. PMID:26871435

  5. Investigation of failure mechanisms in GFRP sandwich structures with face sheet wrinkle defects used for wind turbine blades

    DEFF Research Database (Denmark)

    Leong, Martin Klitgaard; Overgaard, Lars C. T.; Thomsen, Ole Thybo

    2012-01-01

    on the failure modes of sandwich specimens consisting of thick GFRP face sheets with a wrinkle defect and a balsa wood core subjected to in-plane compression loading. Three distinct modes of failure were found, and the strain distributions leading up to these failures were established by use of digital image...... correlation (DIC). Finite element analyses were subsequently conducted to model the response of the test specimens prior to failure, and generally a very good agreement was found with the DIC measurements, although slight differences between the predicted and measured strain fields were observed in the local...... strain values around the wrinkle defect. The Northwestern University (NU) failure criterion was applied to predict failure initiation, and a good correlation with the experimental observations was achieved. © 2011 Elsevier Ltd....

  6. Design of sandwich beams for concentrated loading

    Science.gov (United States)

    Kim, Jongman

    Although sandwich construction offers well-known advantages for high stiffness with light-weight, the problem of designing a sandwich structure to withstand localized loading such as might result from accidental impact, for example, is important. The review of the literature and experimental results performed by the author has shown that current design and analysis procedures are not suitable for predictions of the response of sandwich structures for concentrated loading. To investigate the response of sandwich structures to concentrated loading, experiments were carried out on beam specimens with polyurethane foam core with various densities and thickness, and faces made of AS4/3501-6 carbon/epoxy fiber composite of various thickness under three point loading, which gives a concentrated loading. Overall deformation was measured, along with strains from both surface and embedded gages. Additionally, compression tests and torsion tests have been done for the polyurethane foam used as core in the sandwich beam to characterize its yield properties. Many theories, including classical theory, first order shear deformation theory, higher order theory, elasticity and FE analysis, were compared with the three-point bending experiments. A two-dimensional elasticity solution, which is suitable for sandwich beams under simply support boundary conditions, was used to obtain the strain/stress distribution, failure prediction and optimization work. The common failure modes of sandwich beams have been observed, including core failure in compression and shear failure in core, delamination, and fiber failure in the face. The failure modes can be predicted for sandwich beams under localized loading using elasticity theory and the failure is controlled by a failure mode with the lowest load. An algorithm developed by Swanson and Kim was used to predict the optimum design of sandwich structures for strength to weight under concentrated loading and compared with experimental yield or

  7. Plate Deformation Behavior of Polymer Matrix Composite-Ti Honeycomb-Metal Sandwiches for Pressurized Propulsion Component Applications

    Science.gov (United States)

    Bertelsen, William D.; Shin, E. eugene; Thesken, John C.; Sutter, James K.; Martin, Rich

    2004-01-01

    THe objectives are: 1. To experimentally validate bi-axial plate flexural performance of PMC-Ti H/C-A286 sandwich panels for the internally pressurized RBCC combustion chamber support structure. 2. To explore ASTM 2-D plate flexure test (D 6416) to simulate the internal pressure loading and to correlate the results with analytical and FE modeling based on 2-D flexure properties.

  8. Structural Assessment of Externally Strengthened Bridge Deck Panels

    Science.gov (United States)

    Sim, Jongsung; Oh, Hongseob; Meyer, Christian

    2006-03-01

    Deteriorated concrete bridge decks are strengthened with external bonding technique using either steel plate or various FRPs to enhance the decreased load carrying capacity and serviceability. But the failure characteristics of bridge decks strengthened with various materials can be changed according to mechanical properties of strengthening materials or strengthening scheme as well as the strengthening amount. In this paper, strengthening effect of deck strengthened with carbon fiber sheets, glass fiber sheets or steel plates is compared. And the theoretical load carrying capacity are evaluated using yield line theory and punching shear model properly modified for the strengthened RC member. The panels strengthened with sheet type FRP materials failed more often in a ductile mode, indicating that the failure developed after the rebar yielded.

  9. Luminance uniformity study of OLED lighting panels depending on OLED device structures.

    Science.gov (United States)

    Bae, Hyeong Woo; Son, Young Hoon; Kang, Byoung Yeop; Lee, Jung Min; Nam, Hyoungsik; Kwon, Jang Hyuk

    2015-11-30

    This paper describes the luminance uniformity of OLED lighting panels depending on OLED device structures of single emission layer (single-EML), 2-tandem, and 3-tandem. The luminance distribution is evaluated through the circuit simulation and the fabricated panel measurement. In the simulation results with yellow-green color panels of 30 × 80 mm2 emission area, a 3-tandem structure shows the lowest non-uniformity (1.34% at 7.5V), compared to single-EML (5.67% at 2.8V) and 2-tandem (2.78% at 5.3 V) structures at 1,000 cd/m2. The luminance non-uniformity is germane to the OLED conductance showing that the high luminance-current efficiency is of the most importance to achieve the uniform voltage and luminance distribution. In measurement, a 3-tandem structure also achieves the most uniform luminance distribution with non-uniformity of 4.1% while single EML and 2-tandem structures accomplish 9.6%, and 6.4%, respectively, at ~1,000 cd/m2. In addition, the simulation results ensure that a 3-tandem structure panel is allowed to be enlarged the panel size up to about 5,000 mm2 for lower luminance non-uniformity than 10% without any auxiliary metal electrodes.

  10. The effects of design details on cost and weight of fuselage structures

    Science.gov (United States)

    Swanson, G. D.; Metschan, S. L.; Morris, M. R.; Kassapoglou, C.

    1993-01-01

    Crown panel design studies showing the relationship between panel size, cost, weight, and aircraft configuration are compared to aluminum design configurations. The effects of a stiffened sandwich design concept are also discussed. This paper summarizes the effect of a design cost model in assessing the cost and weight relationships for fuselage crown panel designs. Studies were performed using data from existing aircraft to assess the effects of different design variables on the cost and weight of transport fuselage crown panel design. Results show a strong influence of load levels, panel size, and material choices on the cost and weight of specific designs. A design tool being developed under the NASA ACT program is used in the study to assess these issues. The effects of panel configuration comparing postbuckled and buckle resistant stiffened laminated structure is compared to a stiffened sandwich concept. Results suggest some potential economy with stiffened sandwich designs for compression dominated structure with relatively high load levels.

  11. Mitigation of Blast Effects on Protective Structures by Aluminum Foam Panels

    Directory of Open Access Journals (Sweden)

    Doyeon Byun

    2012-06-01

    Full Text Available Aluminum foams have low density and are attractive materials to mitigate high-speed pressure by blast loads due to high-energy absorption capabilities. In order to develop nonlinear material models for the aluminum foam with different density, mechanical properties of the foam and foam panels under compression, tension, shear and bending moment were obtained by numerous tests. Through the explicit analyses of the foam panels by LS-DYNA, the derived models were verified. Performance of the foam panels with different scaled distances was evaluated by blast tests. Thickness, density and skin plate properties of the panel are the most important parameters to estimate the transmitted pressure to protective structures. Because the pressure of close range blast loading is not uniform, the skin plays an important role in the behavior of the foam. Numerical simulations considering the parameters provided basic design guidelines for the protective structures with sacrificial foam panels. Properly designed panels for the required blast loads can control the transmitted pressure to the target structure under a certain pressure on the yield strength of the foam.

  12. Development of Crashworthy Bottom and Side Structures

    DEFF Research Database (Denmark)

    Naar, H.; Kujala, P.; Simonsen, Bo Cerup

    2002-01-01

    structures. The first structure is a conventional double bottom. In the second structure (presently protected through a patent) the bottom plating is stiffened with hat-profiles instead of bulb profiles. In the third structure the outer shell is an all-steel sandwich panel. In the fourth structure the bottom...

  13. Mechanical Property Analysis on Sandwich Structured Hybrid Composite Made from Natural Fibre, Glass Fibre and Ceramic Fibre Wool Reinforced with Epoxy Resin

    Science.gov (United States)

    Bharat, K. R.; Abhishek, S.; Palanikumar, K.

    2017-06-01

    Natural fibre composites find wide range of applications and usage in the automobile and manufacturing industries. They find lack in desired properties, which are required for present applications. In current scenario, many developments in composite materials involve the synthesis of Hybrid composite materials to overcome some of the lacking properties. In this present investigation, two sandwich structured hybrid composite materials have been made by reinforcing Aloe Vera-Ceramic Fibre Wool-Glass fibre with Epoxy resin matrix and Sisal fibre-Ceramic Fibre Wool-Glass fibre with Epoxy resin matrix and its mechanical properties such as Tensile, Flexural and Impact are tested and analyzed. The test results from the two samples are compared and the results show that sisal fibre reinforced hybrid composite has better mechanical properties than aloe vera reinforced hybrid composite.

  14. Lightweight Composite Intertank Structure

    Science.gov (United States)

    Mehle, Greg V.

    1995-01-01

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

  15. Estimate of the thermal diffusivity of films with a sandwich structure by using pulsed transient analysis and AC calorimetry

    CERN Document Server

    Choi, M H; Park, C H; Kim, S W; Hahn, S H; Seong, D J; Kim, J C

    1999-01-01

    The thermal diffusivity in a direction perpendicular to an epoxy resin film sandwiched between two identical metal layers was measured not only by using a pulsed transient analysis but also by using AC calorimetry. The pulsed transient analysis utilized the surface-temperature decay of the heating pulse from a Q-switched, 2nd harmonic generated Nd:YAG laser. The temperature decay was measured with a HgCdTe infrared detector. After data collection, a nonlinear least-squares regression was performed to estimate the optimal values of several separate thermal parameters by fitting the data to the solutions. Additionally, the thermal diffusivity of the samples was obtained by using the AC calorimetric method which measured the frequency-dependent phase changes of the samples. The thermal diffusivities obtained by the two methods were in the range of 0.07 approx 0.09 x 10 sup - sup 2 cm sup 2 /s, agreed within 8 %, but were lower than the literature values. To improve the results, the contact heat resistance from t...

  16. Medical student selection: choice of a semi-structured panel interview or an unstructured one-on-one interview.

    Science.gov (United States)

    Ann Courneya, Carol; Wright, Kristin; Frinton, Vera; Mak, Edwin; Schulzer, Michael; Pachev, George

    2005-09-01

    Reliability has been shown to be higher in structured medical admissions interviews as compared to unstructured interviews. This study reports the comparison of a proposed semi-structured panel interview with a current individual unstructured medical admissions interview. Inter-rater reliability coefficients were calculated, and correlations were estimated between panel, individual and academic scores. Admission status in 2003 was related to these scores by means of logistic regression. Both individual and panel interviews were significantly correlated with admissions status. The inter rater reliability coefficient (from individual interviews) was 0.12 whereas the interpanel reliability coefficient was 0.52. Panel interview: good across panel and within panel consistency of scoring. No effect of who asked the questions, question order, or interview duration on scoring. No correlation between panel interview scores and academic variables (MCAT, GPA). We found good inter-panel reliability, a high consistency within and between interview panels, and uniformly positive questionnaire responses. The panel interview measures something different from academic variables. These data, in conjunction with a strong sense from the medical and psychological literature supporting the reliability and validity of a semi-structured panel interview, support our decision to replace our individual interview with the panel interview.

  17. Effect of Jointing Mortar on Structural Behaviour of Wall Panels ...

    African Journals Online (AJOL)

    emerging as the grand eco-material for building construction for the 21st century due to its availability, environmental/cultural appropriateness, structural adequacy, familiarity to the local people, “breathability”, amongst others. Accordingly, both ...

  18. Fracture Analysis of Debonded Sandwich Columns Under Axial Compression

    DEFF Research Database (Denmark)

    May, A.; Avilés, F.; Berggreen, Christian

    A sandwich structure consists of two strong and stiff face sheets bonded to a weak low density core. The large separation between the face sheets provides increased bending rigidity and strength at low weight cost. Thus, sandwich structures frequently present better mechanical properties than mon...

  19. STRUCTURAL EVALUATION OF PSSDB WALL PANEL WITH SQUARE OPENING AND VARIED SCREW SPACING

    Directory of Open Access Journals (Sweden)

    SITI HAWA HAMZAH

    2009-03-01

    Full Text Available Profiled steel sheet dry boards or PSSDB system is an alternative composite construction system comprising of profiled steel sheet compositely connected to dry boards by self-tapping self-driving screws. PSSDB system was used widely as flooring system in the lightweight construction of buildings and office space in factories. Due to its superiority in the installation techniques, PSSDB system was expanded in the application as load bearing wall panel system in buildings. The PSSDB system is as an alternative construction technique on load bearing wall panel that offers cost savings synonymously with the rapid progress of science and technology which leads to the shift from traditional utilization of construction materials to newer construction techniques. A finite element analysis was carried out to determine the effect of screw spacing on the PSSDB wall panel. The spacing selected was between 100 mm to 500 mm, at an increment of 100 mm in each different model. The wall panel measured 3000 mm by 3000 mm with a 1200 mm square window opening, 78 mm thick and butt joints vertically positioned in the dry boards. This paper looks into the system as load bearing wall panels, analyzing it under axial compressive load using established Finite Element technique. The deformation profile of the PSSDB wall panel system showed a single curvature deformation profile, maximum lateral displacement at two-thirds wall panel height and critical sections at the upper corners of the square opening. The finite element analysis had provided good prediction of the structural behavior of the PSSDB wall panel system and it is concluded that the PW200 model possesses the optimum arrangement of the fixing screws used.

  20. Evolution of integrated panel structural design and interfaces for PV power plants

    Science.gov (United States)

    Arnett, J. C.; Anderson, A. J.; Robertson, R. E.

    1983-11-01

    The evolution of integrated photovoltaic (PV) panel design at ARCO Solar is discussed. Historically, framed PV modules of about 1 x 4-ft size were individually mounted in the field on fixed support structures and interconnected electrically with cables to build higher-power arrays. When ARCO Solar saw the opportunity in 1982 to marry its PV modules with state-of-the-art heliostat trackers developed by ARCO Power Systems, it became obvious that mounting individual modules was impractical. For this project, the framed modules were factory-assembled into panels and interconnected with cables before being mounted on the trackers. Since then, ARCO Solar made considerable progress and gained substantial experience in the design and fabrication of large PV panels. Constraints and criteria considered in these design activities included static and dynamic loads; assembly and transportation equipment and logistics, structural and electrical interfaces, and safety and grounding concerns.

  1. Structure and Reactivity of Half-Sandwich Rh(+3) and Ir(+3) Carbene Complexes. Catalytic Metathesis of Azobenzene Derivatives.

    Science.gov (United States)

    Tindall, Daniel J; Werlé, Christophe; Goddard, Richard; Philipps, Petra; Farès, Christophe; Fürstner, Alois

    2018-02-07

    Traditional rhodium carbene chemistry relies on the controlled decomposition of diazo derivatives with [Rh 2 (OAc) 4 ] or related dinuclear Rh(+2) complexes, whereas the use of other rhodium sources is much less developed. It is now shown that half-sandwich carbene species derived from [Cp*MX 2 ] 2 (M = Rh, Ir; X = Cl, Br, I, Cp* = pentamethylcyclopentadienyl) also exhibit favorable application profiles. Interestingly, the anionic ligand X proved to be a critical determinant of reactivity in the case of cyclopropanation, epoxide formation and the previously unknown catalytic metathesis of azobenzene derivatives, whereas the nature of X does not play any significant role in -OH insertion reactions. This perplexing disparity can be explained on the basis of spectral and crystallographic data of a representative set of carbene complexes of this type, which could be isolated despite their pronounced electrophilicity. Specifically, the donor/acceptor carbene 10a derived from ArC(═N 2 )COOMe and [Cp*RhCl 2 ] 2 undergoes spontaneous 1,2-migratory insertion of the emerging carbene unit into the Rh-Cl bond with formation of the C-metalated rhodium enolate 11. In contrast, the analogous complexes 10b,c derived from [Cp*RhX 2 ] 2 (X = Br, I) as well as the iridium species 13 and 14 derived from [Cp*IrCl 2 ] 2 are sufficiently stable and allow true carbene reactivity to be harnessed. These complexes are competent intermediates for the catalytic metathesis of azobenzene derivatives, which provides access to α-imino esters that would be difficult to make otherwise. Rather than involving metal nitrenes, the reaction proceeds via aza-ylides that evolve into diaziridines; a metastable compound of this type has been fully characterized.

  2. A DYNAMIC PANEL MODEL OF CAPITAL STRUCTURE AND AGENCY COST IN NIGERIAN LISTED COMPANIES

    OpenAIRE

    Dauda Mohammed

    2013-01-01

    This study examines the impact of agency costs on capital structure of Nigeria listed companies for the period of 2000-2006. Using a dynamic panel model, the study demonstrates the extent to which asset utilization helps explain the financing structure of Nigerian firms. The main finding shows an inverse relationship between capital structure and agency costs of Nigerian firms. Thus, the negative coefficient on the agency cost variable indicates that, on average, the management of Nigerian fi...

  3. Causal feedforward control of a stochastically excited fuselage structure with active sidewall panel.

    Science.gov (United States)

    Misol, Malte; Haase, Thomas; Monner, Hans Peter; Sinapius, Michael

    2014-10-01

    This paper provides experimental results of an aircraft-relevant double panel structure mounted in a sound transmission loss facility. The primary structure of the double panel system is excited either by a stochastic point force or by a diffuse sound field synthesized in the reverberation room of the transmission loss facility. The secondary structure, which is connected to the frames of the primary structure, is augmented by actuators and sensors implementing an active feedforward control system. Special emphasis is placed on the causality of the active feedforward control system and its implications on the disturbance rejection at the error sensors. The coherence of the sensor signals is analyzed for the two different disturbance excitations. Experimental results are presented regarding the causality, coherence, and disturbance rejection of the active feedforward control system. Furthermore, the sound transmission loss of the double panel system is evaluated for different configurations of the active system. A principal result of this work is the evidence that it is possible to strongly influence the transmission of stochastic disturbance sources through double panel configurations by means of an active feedforward control system.

  4. The Structure Of The Tapping Panel Of Raphia hookeri,(Mann and ...

    African Journals Online (AJOL)

    Journal of Agriculture, Forestry and the Social Sciences ... which varies from 7 to 60 days, sap flow is induced through the removal of thin slices of tissues of three major structures in the panel- the emerging petioles of the short spear leaves, the emerging primary branch inflorescences and the main inflorescence axis.

  5. Status and trends : profile of structural panels in the United States and Canada

    Science.gov (United States)

    Henry Spelter; David McKeever; Matthew Alderman

    2006-01-01

    This paper provides an overview of the North American (United States and Canada) structural panel industry, which consists of softwood plywood and oriented strandboard (OSB). The paper describes the evolution of overall capacities, effective capacity utilization, and manufacturing costs. As part of that, it describes changes in industry operating parameters such as...

  6. Structural analysis and sizing of stiffened, metal matrix composite panels for hypersonic vehicles

    Science.gov (United States)

    Collier, Craig S.

    1992-12-01

    The present method for strength and stability analyses of stiffened, fiber-reinforced composite panels to be used in hypersonic vehicle structures is of great generality, and can be linked with planar finite-element analysis (FEA). Nonlinear temperature and load-dependent material data for each laminate are used to 'build-up' the stiffened panel's membrane, bending, and membrane-bending coupling stiffness terms, as well as thermal coefficients. The resulting, FEA-solved thermomechanical forces and moments are used to calculate strain at any location in the panel; this allows an effective ply-by-ply orthotropic strength analysis to be conducted, together with orthotropic instability checks for each laminated segment of the cross-section.

  7. Adaptive support for aircraft panel testing: New method and its experimental verification on a beam structure

    Science.gov (United States)

    Sachau, Delf; Baschke, Manuel

    2017-04-01

    Acoustic transmissibility of aircraft panels is measured in full-scale test rigs. The panels are supported at their frames. These boundary conditions do not take into account the dynamic influence of the fuselage, which is significant in the frequency range below 300 Hz. This paper introduces a new adaptive boundary system (ABS). It combines accelerometers and electrodynamic shakers with real-time signal processing. The ABS considers the dynamic effect of the fuselage on the panel. The frames are dominating the dynamic behaviour of a fuselage in the low-frequency range. Therefore, the new method is applied to a beam representing a frame of the aircraft structure. The experimental results are evaluated and the precision of the ABS is discussed. The theoretical apparent mass representing the cut-off part of a frame is calculated and compared with the apparent mass, as provided by the ABS. It is explained how the experimental set-up limits the precision of the ABS.

  8. Design and fabrication of a skin stringer discrete tube actively cooled structural panel

    Science.gov (United States)

    Anthony, F. M.

    1978-01-01

    The design optimization and practical implementation of actively cooled structural panel concepts was investigated. The desired actively cooled structural panel consisted of the cooled skin and a substructure. The primary load carrying components were fabricated from 2024-T3 aliminum alloy. The 3003-H14 coolant passage tubing was chosen because of its excellent corrosion resistance, workability needed to obtain the desired cross sectional shape, and strength. The Epon 951 adhesive was selected for its excellent structural properties and is the thinnest of available films, 0.064 mm. The Eccobond 58C silver filled epoxy was chosen because of its high thermal conductivity, and the alumina filled Epon 828 was chosen for structural and expansion characteristics.

  9. FEA of the Variations in Sound Insulation in Nominally Identical Prefabricated Lightweight Timber Panel Structures

    DEFF Research Database (Denmark)

    Kirkegaard, Poul Henning; Andersen, Lars

    2013-01-01

    The measurements of sound propagation in buildings usually show a variation between nominally identical constructed structures. These variations can be due to variations in structural properties, measurement uncertainties or workmanship related factors. Better knowledge about the source...... for these variations can lead to lowered production costs. The present paper presents a numerical analysis of the variations in sound propagation of norminally identical prefabricated lightweight timber panel structues. By using the commercial FEA software ABAQUS, a parameter study is carried out regarding variation...

  10. Predicting safe sandwich production

    DEFF Research Database (Denmark)

    Birk, Tina; Duan, Zhi; Møller, Cleide Oliveira de Almeida

    2014-01-01

    Time and temperature control is crucial to avoid growth of pathogens during production and serving of cold ready-to-eat meals. The Danish guidelines state that chilled foods, such as sandwiches, should not be outside the cold chain for more than 3 hours including the time for preparation and serv......Time and temperature control is crucial to avoid growth of pathogens during production and serving of cold ready-to-eat meals. The Danish guidelines state that chilled foods, such as sandwiches, should not be outside the cold chain for more than 3 hours including the time for preparation...... and serving. However, Danish sandwich producing companies find it challenging to comply with this and have expressed a need for more flexibility. The Danish guidelines do allow for a prolongation of the acceptable time outside the cold chain, if the safety of the specific production can be documented....... There is, therefore, room for developing targeted tools for evaluating the time-temperature scenarios in sandwich production. This study describes a decision support tool developed to offer the producers more flexibility. Based on time/temperature measurements obtained during preparation combined...

  11. Three-dimensional sandwich-structured NiMn2O4@reduced graphene oxide nanocomposites for highly reversible Li-ion battery anodes

    Science.gov (United States)

    Huang, Jiarui; Wang, Wei; Lin, Xirong; Gu, Cuiping; Liu, Jinyun

    2018-02-01

    A sandwich-structured NiMn2O4@reduced graphene oxide (NiMn2O4@rGO) nanocomposite consisting of ultrathin NiMn2O4 sheets uniformly anchored on both sides of a three-dimensional (3D) porous rGO is presented. The NiMn2O4@rGO nanocomposites prepared through a dipping process combining with a hydrothermal method show a good electrochemical performance including a high reversible capability of 1384 mAh g-1 at 1000 mA g-1 over 1620 cycles, and an superior rate performance. Thus, a full cell consisting of a commercial LiCoO2 cathode and the NiMn2O4@rGO anode delivers a stable capacity of about 1046 mAh g-1 (anode basis) after cycling at 50 mA g-1 for 60 times. It is demonstrated that the 3D porous composite structure accommodates the volume change during the Li+ insertion/extraction process and facilitates the rapid transport of ions and electrons. The high performance would enable the presented NiMn2O4@rGO nanocomposite a promising anode candidate for practical applications in Li-ion batteries.

  12. Half-sandwich structure of cyclopentadienyl dialuminum [Al2(eta5-C5H5)] from pulsed-field ionization electron spectroscopy and ab initio calculations.

    Science.gov (United States)

    Lei, Yuxiu; Yang, Dong-Sheng

    2008-02-21

    Cyclopentadienyl dialuminum [Al2Cp, Cp = C5H5] was prepared in a pulsed laser ablation cluster beam source and identified with a time-of-flight photoionization mass spectrometer. The high-resolution electron spectrum of this complex was obtained using pulsed-field ionization zero electron kinetic energy (ZEKE) photoelectron spectroscopy. Three isomeric structures with two Al atoms residing on the same or opposite sites of the Cp plane were predicted by second-order Møller-Plesset perturbation theory. A half-sandwich structure with an aluminum dimer perpendicular to the Cp plane was identified by the experiment. The ground electronic states of the neutral and ionized species are 2A' ' in Cs symmetry and 1A1 in C5v symmetry, respectively. In both the neutral and ionic states, one of the Al2 atoms binds with five carbons, and the metal-ligand bonding consists of orbital and electrostatic contributions. Ionization of the 2A' ' neutral state enhances the metal-ligand bonding but weakens the metal-metal interaction.

  13. Non-linear analytical solutions for laterally loaded sandwich plates

    DEFF Research Database (Denmark)

    Riber, Hans Jørgen

    1997-01-01

    This work focuses on the response of orthotropic sandwich composite plates with large deflections due to high lateral loads. The results have special application to the design of ship structures. A geometrical nonlinear theory is outlined, on the basis of the classical sandwich plate theory...

  14. RC structures strengthened by metal shear panels: experimental and numerical analysis

    Science.gov (United States)

    De Matteis, G.; Formisano, A.; Mazzolani, F. M.

    2008-07-01

    Metal shear panels (MSPs) may be effectively used as a lateral load resisting system for framed structures. In the present paper, such a technique is applied for the seismic protection of existing RC buildings, by setting up a specific design procedure, which has been developed on the basis of preliminary full-scale experimental tests. The obtained results allowed the development of both simplified and advanced numerical models of both the upgraded structure and the applied shear panels. Also, the proposed design methodology, which is framed in the performance base design philosophy, has been implemented for the structural upgrading of a real Greek existing multi-storey RC building. The results of the numerical analysis confirmed the effectiveness of the proposed technique, also emphasising the efficiency of the implemented design methodology.

  15. Physical and mechanical properties of plywood panels manufactures with tropical plantation species for structural use

    Directory of Open Access Journals (Sweden)

    Diego Camacho

    2012-06-01

    Full Text Available Concrete, steel and plastics are the materials used for construction in Costa Rica. Meanwhile, wood from plantation are being introduced in the market. The present study aims to characterize and measured some physical and mechanical properties of plywood panels manufactured with veneers of Gmelina arborea, Tectona grandis and Acacia mangium coming from forest plantations for structural use. It was produced three plywood boards of each species and general characterization of them was done, and physical and mechanical properties were determined. The results shown that panels manufactured with T. grandis wood presented physical and mechanical properties higher than G. arborea and A. mangium. In accordance with standards of Voluntary Products Standart PS 1-95 and PS 1-09 of the United States, structural plywood of G. arborea can be grouped in grade 3, and plywood manufactured with T. grandis and A. mangium wood in grade 2. All species can be used in the manufacture of structural elements.

  16. Structural and magnetic properties of Ni{sub 78}Fe{sub 22} thin films sandwiched between low-softening-point glasses and application in spin devices

    Energy Technology Data Exchange (ETDEWEB)

    Misawa, Takahiro; Mori, Sumito [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Komine, Takashi [Faculty of Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan); Fujioka, Masaya; Nishii, Junji [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Kaiju, Hideo, E-mail: kaiju@es.hokudai.ac.jp [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan)

    2016-12-30

    Graphical abstract: This paper presents the first demonstration of the formation of Ni{sub 78}Fe{sub 22} thin films sandwiched between low-softening-point (LSP) glasses used in spin quantum cross (SQC) devices and the theoretical prediction of spin filter effect in Ni{sub 78}Fe{sub 22}-based SQC devices. The fomation of the LSP-glass/Ni{sub 78}Fe{sub 22}/LSP-glass structures was successfully demonstrated using a newly proposed thermal pressing technique. Interestingly, this technique gives rise to both a highly-oriented crystal growth in Ni{sub 78}Fe{sub 22} thin films and a 100-fold enhancement in coercivity, in contrast to those of as-deposited Ni{sub 78}Fe{sub 22} thin films. This remarkable increase in coercivity can be explained by the calculation based on two-dimensional random anisotropy model. These excellent features on structural and magnetic properties allowed us to achieve that the stray magnetic field was uniformly generated from the Ni{sub 78}Fe{sub 22} thin-film edge in the direction perpendicular to the cross section of the LSP-glass/Ni{sub 78}Fe{sub 22}/LSP-glass structures. As we calculated the stray magnetic field generated between the two edges of Ni{sub 78}Fe{sub 22} thin-film electrodes in SQC devices, a high stray field of approximately 5 kOe was generated when the gap distance between two edges of the Ni{sub 78}Fe{sub 22} thin-film electrodes was less than 5 nm and the thickness of Ni{sub 78}Fe{sub 22} was greater than 20 nm. These experimental and calculated results suggest that Ni{sub 78}Fe{sub 22} thin films sandwiched between LSP glasses can be used as electrodes in SQC devices, providing a spin-filter effect, and also our proposed techniques utilizing magnetic thin-film edges will open up new opportunities for the creation of high performance spin devices, such as large magnetoresistance devices and nanoscale spin injectors. Our paper is of strong interest to the broad audience of Applied Surface Science, as it demonstrates that the

  17. EXPERIMENTAL ANALYSIS OF FLEXURAL STRENGTH ON GLASS FIBER SANDWICH COMPOSITE BY VARYING Z-PINS PITCHES

    OpenAIRE

    Pravin*, Jeyapratha

    2016-01-01

    This paper ambit to evaluate the flexural strength of glass fiber sandwich panels with varying z-pins pitches. Failure of sandwich panel are delamination and core shear, to minimize the crack propagation, pins are inserted in z-direction, by varying pitches through its thickness. During the insertion of pin, may cause the material some damage. Despite the damage, flexural property does not affected due interpolation of pins. Although the experiment were pull out with a phenomenal results of z...

  18. Structural affection of the integration of the solar panels in existing buildings; Afeccion estructural de la integracion de los paneles solares en edificios existentes

    Energy Technology Data Exchange (ETDEWEB)

    Mencias, D. C.; Arroba, M. F.

    2008-07-01

    For a short time, is obligatory to install solar and/or photovoltaic panels, not only in new buildings, even those who are subjected to a important reform or rehabilitation. The installation of these panels, involves a series of structural impacts on the structure of the buildings where they are installed, which originally had not been planned or considered in loads evaluation. These new actions are originated both in the weight of the solar elements as a resistance that oppose the wind force and the consequent counterweights. This communication proposes the analysis of the reduction that these new loads cause in safety factors considered in the initial calculation. Permanent loads influence direct their own panels and the accumulation of deposits and derivative, such as caused by the counterweights installed for the wind, are analyzed in Ultimated State Limits. (Author)

  19. Controlling the electronic and geometric structures of 2D insertions to realize high performance metal/insertion-MoS2 sandwich interfaces.

    Science.gov (United States)

    Su, Jie; Feng, Liping; Zeng, Wei; Liu, Zhengtang

    2017-06-08

    Metal/insertion-MoS2 sandwich interfaces are designed to reduce the Schottky barriers at metal-MoS2 interfaces. The effects of geometric and electronic structures of two-dimensional (2D) insertion materials on the contact properties of metal/insertion-MoS2 interfaces are comparatively studied by first-principles calculations. Regardless of the geometric and electronic structures of 2D insertion materials, Fermi level pinning effects and charge scattering at the metal/insertion-MoS2 interface are weakened due to weak interactions between the insertion and MoS2 layers, no gap states and negligible structural deformations for MoS2 layers. The Schottky barriers at metal/insertion-MoS2 interfaces are induced by three interface dipoles and four potential steps that are determined by the charge transfers and structural deformations of 2D insertion materials. The lower the electron affinities of 2D insertion materials, the more are the electrons lost from the Sc surface, resulting in lower n-type Schottky barriers at Sc/insertion-MoS2 interfaces. The larger the ionization potentials and the thinner the thicknesses of 2D insertion materials, the fewer are the electrons that accumulate at the Pt surface, leading to lower p-type Schottky barriers at Pt/insertion-MoS2 interfaces. All Sc/insertion-MoS2 interfaces exhibited ohmic characters. The Pt/BN-MoS2 interface exhibits the lowest p-type Schottky barrier of 0.52 eV due to the largest ionization potential (∼6.88 eV) and the thinnest thickness (single atomic layer thickness) of BN. These results in this work are beneficial to understand and design high performance metal/insertion-MoS2 interfaces through 2D insertion materials.

  20. Design and fabrication of Rene 41 advanced structural panels. [their performance under axial compression, shear, and bending loads

    Science.gov (United States)

    Greene, B. E.; Northrup, R. F.

    1975-01-01

    The efficiency was investigated of curved elements in the design of lightweight structural panels under combined loads of axial compression, inplane shear, and bending. The application is described of technology generated in the initial aluminum program to the design and fabrication of Rene 41 panels for subsequent performance tests at elevated temperature. Optimum designs for two panel configurations are presented. The designs are applicable to hypersonic airplane wing structure, and are designed specifically for testing at elevated temperature in the hypersonic wing test structure located at the NASA Flight Research Center. Fabrication methods developed to produce the Rene panels are described, and test results of smaller structural element specimens are presented to verify the design and fabrication methods used. Predicted strengths of the panels under several proposed elevated temperature test load conditions are presented.

  1. Vibration Analysis of Cylindrical Sandwich Aluminum Shell with Viscoelastic Damping Treatment

    Directory of Open Access Journals (Sweden)

    Tai-Hong Cheng

    2013-01-01

    Full Text Available This paper has applied the constrained viscoelastic layer damping treatments to a cylindrical aluminum shell using layerwise displacement theory. The transverse shear, the normal strains, and the curved geometry are exactly taken into account in the present layerwise shell model, which can depict the zig-zag in-plane and out-of-plane displacements. The damped natural frequencies, modal loss factors, and frequency response functions of cylindrical viscoelastic aluminum shells are compared with those of the base thick aluminum panel without a viscoelastic layer. The thickness and damping ratio of the viscoelastic damping layer, the curvature of proposed cylindrical aluminum structure, and placement of damping layer of the aluminum panel were investigated using frequency response function. The presented results show that the sandwiched viscoelastic damping layer can effectively suppress vibration of cylindrical aluminum structure.

  2. The Influence of GI and GII on the Compression After Impact Strength of Carbon Fiber/Epoxy Laminates and Sandwich Structure

    Science.gov (United States)

    Nettles, A. T.; Scharber, L. L.

    2017-01-01

    This study measured the compression after impact strength of IM7 carbon fiber laminates made from epoxy resins with various mode I and mode II toughness values to observe the effects of these toughness values on the resistance to damage formation and subsequent residual compression strength-carrying capabilities. Both monolithic laminates and sandwich structure were evaluated. A total of seven different epoxy resin systems were used ranging in approximate GI values of 245-665 J/sq m and approximate GII values of 840-2275 J/sq m. The results for resistance to impact damage formation showed that there was a direct correlation between GII and the planar size of damage, as measured by thermography. Subsequent residual compression strength testing suggested that GI had no influence on the measured values and most of the difference in compression strength was directly related to the size of damage. Thus, delamination growth assumed as an opening type of failure mechanism does not appear to be responsible for loss of compression strength in the specimens examined in this study.

  3. Theoretical study of structure, bonding, and electronic behavior of novel sandwich complexes Os3(C6H6) n ( n = 1, 2)

    Science.gov (United States)

    Zhou, K.; Zhao, C. B.; Huang, W. D.

    2017-11-01

    The correlations between structural and electronic properties of the monolayer cluster Os3 and sandwich complexes of Os3(C6H6) n ( n = 1, 2) were studied with density functional theory. Every Os adopts η2 fashion to coordinate with C6H6 in Os3(C6H6), while every Os adopts η2 and η1 fashion to coordinate with below and above C6H6 rings in Os3(C6H6)2. η2 fashion is σ donation and π back bond, and η1 fashion belong to σ bond. The first binding energy between Os3 and below C6H6 ring is-114.23 kJ/mol, which is weaker than the second binding energy with-174.16 kJ/mol between Os3(C6H6) and above C6H6 ring. The reason is that the change of spin multiplicity is different, which leads the symmetry of Os3(C6H6)2 to be broken.

  4. Emission enhancement in indium zinc oxide(IZO)/Ag/IZO sandwiched structure due to surface plasmon resonance of thin Ag film

    Energy Technology Data Exchange (ETDEWEB)

    Kiba, Takayuki, E-mail: tkiba@mail.kitami-it.ac.jp [Department of Materials Science and Engineering, Kitami Institute of Technology, Kitami 090-8507 (Japan); Yanome, Kazuki; Kawamura, Midori; Abe, Yoshio; Kim, Kyung Ho [Department of Materials Science and Engineering, Kitami Institute of Technology, Kitami 090-8507 (Japan); Takayama, Junichi; Murayama, Akihiro [Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814 (Japan)

    2016-12-15

    Highlights: • 2–8-fold enhancement was observed for the defect related emission in IZO with Ag thin film. • The results of time-resolved PL spectra suggested the increase in radiative recombination rate. • The emission enhancement is due to surface plasmonic resonance effect of Ag thin film. • Non-radiative process of the Ag surface plasmon also affects the enhancement efficiency. - Abstract: We report on a photoluminescence (PL) enhancement in IZO/Ag/IZO sandwiched structure via surface plasmonic effects of 14 nm-thick Ag film. In the presence of Ag thin film, the 2–8-fold enhancement was observed for the broad PL around 2.34 eV, which can be originated from defect states in amorphous IZO film. The results of time-resolved PL spectra suggested that the increase in radiative recombination rate, and the maximum Purcell factor of 19 was estimated from the analysis of the PL decay profiles. The comparison between the results of static- and dynamic-PL measurement suggests that the non-radiative process after the excitation of the surface plasmon of the silver film also affects the total efficiency of the emission enhancement.

  5. Co(OH)2/RGO/NiO sandwich-structured nanotube arrays with special surface and synergistic effects as high-performance positive electrodes for asymmetric supercapacitors.

    Science.gov (United States)

    Xu, Han; Zhang, Chi; Zhou, Wen; Li, Gao-Ren

    2015-10-28

    High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (∼1470 F g(-1) at 5 mV s(-1)) and excellent cycling stability with ∼98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg(-1)), a high power density (27.5 kW kg(-1)) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs.

  6. Mechanical behavior of a sandwich with corrugated GRP core: numerical modeling and experimental validation

    Directory of Open Access Journals (Sweden)

    D. Tumino

    2014-10-01

    Full Text Available In this work the mechanical behaviour of a core reinforced composite sandwich structure is studied. The sandwich employs a Glass Reinforced Polymer (GRP orthotropic material for both the two external skins and the inner core web. In particular, the core is designed in order to cooperate with the GRP skins in membrane and flexural properties by means of the addition of a corrugated laminate into the foam core. An analytical model has been developed to replace a unit cell of this structure with an orthotropic equivalent thick plate that reproduces the in plane and out of plane behaviour of the original geometry. Different validation procedures have been implemented to verify the quality of the proposed method. At first a comparison has been performed between the analytical model and the original unit cell modelled with a Finite Element mesh. Elementary loading conditions are reproduced and results are compared. Once the reliability of the analytical model was assessed, this homogenised model was implemented within the formulation of a shell finite element. The goal of this step is to simplify the FE analysis of complex structures made of corrugated core sandwiches; in fact, by using the homogenised element, the global response of a real structure can be investigated only with the discretization of its mid-surface. Advantages are mainly in terms of time to solution saving and CAD modelling simplification. Last step is then the comparison between this FE model and experiments made on sandwich beams and panels whose skins and corrugated cores are made of orthotropic cross-ply GRP laminates. Good agreement between experimental and numerical results confirms the validity of the proposed model.

  7. Comparison of STRUCTURAL-ACOUSTIC Control Designs on AN Active Composite Panel

    Science.gov (United States)

    BINGHAM, B.; ATALLA, M. J.; HAGOOD, N. W.

    2001-07-01

    This work presents a comparison of three technologies for structural-acoustic control that, while prevalent in the literature, had not been compared on a single structure. The comparison is generalizable because the techniques are implemented on a panel structure representative of a more complex structure (e.g., an aircraft fuselage, a submarine vehicle hull, a satellite payload shroud, etc.). The test-bed used for this comparison is a carbon-fiber composite panel manufactured with embedded active fiber composite actuators. Since such integrated structures constitute a continued avenue of research, the manufacturing and performance of this structure is illustrated. The design of the test-bed is guided by an effort to achieve a dynamic response similar to a single panel in a typical aircraft or rotorcraft fuselage.Existing active control architectures for broadband acoustic radiation reduction are compared both analytically and experimentally on a representative structure to quantify the capabilities and limitations of the existing control methodologies. Specifically, three broad categories of control are compared: classical feedback (rate feedback), optimal feedback (linear quadratic Gaussian), and adaptive feedforward control (x -filtered least mean square). The control architectures implemented during this study are all single-input/single-output in order to allow a fair comparison of the issues involved in the design, as well as the use and performance of each approach. Both the vibration and the acoustic performance are recorded for each experiment under equivalent conditions to allow a generalizable comparison. Experimental results lead to conclusions pertaining to the application of active structural-based control to improve the acoustic performance of more complex structures.

  8. The Effects of Foam Thermal Protection System on the Damage Tolerance Characteristics of Composite Sandwich Structures for Launch Vehicles

    Science.gov (United States)

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

    2011-01-01

    For any structure composed of laminated composite materials, impact damage is one of the greatest risks and therefore most widely tested responses. Typically, impact damage testing and analysis assumes that a solid object comes into contact with the bare surface of the laminate (the outer ply). However, most launch vehicle structures will have a thermal protection system (TPS) covering the structure for the majority of its life. Thus, the impact response of the material with the TPS covering is the impact scenario of interest. In this study, laminates representative of the composite interstage structure for the Ares I launch vehicle were impact tested with and without the planned TPS covering, which consists of polyurethane foam. Response variables examined include maximum load of impact, damage size as detected by nondestructive evaluation techniques, and damage morphology and compression after impact strength. Results show that there is little difference between TPS covered and bare specimens, except the residual strength data is higher for TPS covered specimens.

  9. Buckling driven debonding in sandwich columns

    DEFF Research Database (Denmark)

    Østergaard, Rasmus Christian

    2008-01-01

    results from two mechanisms: (a) interaction of local debond buckling and global buckling and (b) the development of a damaged zone at the debond crack tip. Based on the pronounced imperfection sensitivity, the author predicts that an experimental measurement of the strength of sandwich structures may...... exhibit a large scatter caused by geometrical variations between test specimens. (C) 2007 Elsevier Ltd. All rights reserved....

  10. Planarity certification of ATLAS Micromegas detector panels

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Ralph; Biebel, Otmar; Bortfeldt, Jonathan; Flierl, Bernhard; Hertenberger, Ralf; Loesel, Philipp; Herrmann, Maximilian [LMU Muenchen (Germany); Zibell, Andre [JMU Wuerzburg (Germany)

    2016-07-01

    During the second long LHC shutdown, 2019/20, the precision tracking detectors of the ATLAS muon spectrometer in the inner end caps will be replaced using Micromegas, a planar gas-detector technology. Modules of 2 m{sup 2} area are built in quadruplets from five precisely planar sandwich panels that define the anodes and the cathodes of the four active detector planes. A panel is composed of three consecutive layers FR4 - aluminum honeycomb - FR4. Single plane spatial particle resolution below 100 μm is achievable when the deviations from planarity of the strip-anodes do not exceed 80 μm RMS over the whole active area and the parallelism of the readout strips is within 30 μm. In order to measure the dimensional accuracy of each panel, laser distance sensors combined with a coordinate measurement system have been investigated. The sensor requirements to measure the planarity of the panels are a resolution of 0.3 μm and a beam spot diameter of ∼20 μm, well below 100 μ m the size of the smallest structures. We report on achieved planarities of the panels and the performance of the laser sensor system. A panel with an RMS better than 30 μm was build and the evolution of its planarity due to humidity and temperature effects is shown.

  11. Thermal annealing and SHI irradiation induced modifications in sandwiched structured Carbon-gold-Carbon (a-C/Au/a-C) nanocomposite thin film

    Science.gov (United States)

    Singh, S. K.; Singhal, R.

    2017-09-01

    In the present work, we study the annealing and swift heavy ion (SHI) beam induced modifications in the optical and structural properties of sandwiched structured Carbon-gold-Carbon (a-C/Au/a-C) nanocomposite (NCs) thin films. The NCs thin films were synthesized by electron-beam evaporation technique at room temperature with ∼30 nm thickness for both carbon layer and ∼6 nm for gold layer. Gold-carbon NCs thin films were annealed in the presence of argon at a temperature of 500 °C, 600 °C and 750 °C. The NCs thin films were also irradiated with 90 MeV Ni ions beam with different ion fluences in the range from 3 × 1012, 6 × 1012 and 1 × 1013 ions/cm2. Surface plasmon resonance (SPR) of Au nanoparticles are not observed in the pristine film but, after annealing at temperature of 600 °C and 750 °C, it was clearly seen at ∼534 nm as confirmed by UV-visible absorption spectroscopy. 90 MeV Ni irradiated thin film at the fluence of 1 × 1013 ions/cm2 also show strong absorption band at ∼534 nm. The growth and size of Au nanoparticle for pristine and 90 MeV Ni ion irradiated thin film with fluence of 1 × 1013 ions/cm2, were estimated by Transmission electron microscopy (TEM) images with the bi-model distribution. The size of the gold nanoparticle (NPs) was found to be ∼4.5 nm for the pristine film and ∼5.4 nm for the irradiated film at a fluence of 1 × 1013 ions/cm2. The thickness and metal atomic fraction in carbon matrix were estimated by Rutherford backscattering spectroscopy (RBS). The effect of annealing as well as heavy ion irradiation on D and G band of carbon matrix were studied by Raman spectroscopy.

  12. Introduction to Analysis and Design of Plate Panels

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Lützen, Marie

    panels and to present some fairly easy methods and results to be used in the design phase to judge, whether a plate panel can be considered safe from a structural point of view or requires a more detailed numerical analysis, typically using the Finite Element Method. Furthermore, a short introduction...... panels used in ship structures) and Jones (1997) (dealing mostly with impact responses). Finally, a recent book also including shell structures is Ventsel and Krauthammer (2001). Compared to the textbooks cited above the present treatment puts more emphasis on stiffened plates than usually seen. However......, composite materials as glass-fibre-reinforced plates, sandwich plates and reinforced concrete plates are not included as they are topics for other courses. The present notes are mainly based on Pedersen and Jensen (1983), written in Danish. The first version of the notes was prepared by Marie L...

  13. Effect of Thin Cement-Based Renders on the Structural Response of Masonry Wall Panels

    Directory of Open Access Journals (Sweden)

    Marco Corradi

    2018-01-01

    Full Text Available URM (Unreinforced Masonry historic buildings can be generally arranged into three categories: adobe, brick and stone masonry. However, a common feature of URM structures is typically the low mechanical properties of the masonry material, especially in terms of shear strength. URM buildings are not amenable to seismic analysis, and the relatively low strength of stone and brickwork masonry often requires expensive and invasive retrofitting intervention. Hard, intractable stones broke artificially or naturally into random shapes were often used for construction in many parts of Europe and constitute the main material of historic buildings. Thin, cement or lime-based renders are often employed to protect masonry construction, but these are frequently ignored in analysis and design. This paper shows how standard, thin, cement-based renderings can highly enhance the lateral load-capacity and shear stiffness of wall panels. An experimental campaign was carried out on-site to assess the effect of cement-based renders. In detail, compression and shear tests were conducted on twelve full-scale wall panels up to failure, and comparisons are presented to study the effect of cement-based renders on the structural behavior of stone and brickwork masonry panels.

  14. Shear Behavior of 3D Woven Hollow Integrated Sandwich Composites: Experimental, Theoretical and Numerical Study

    Science.gov (United States)

    Zhou, Guangming; Liu, Chang; Cai, Deng'an; Li, Wenlong; Wang, Xiaopei

    2017-08-01

    An experimental, theoretical and numerical investigation on the shear behavior of 3D woven hollow integrated sandwich composites was presented in this paper. The microstructure of the composites was studied, then the shear modulus and load-deflection curves were obtained by double lap shear tests on the specimens in two principal directions of the sandwich panels, called warp and weft. The experimental results showed that the shear modulus of the warp was higher than that of the weft and the failure occurred in the roots of piles. A finite element model was established to predict the shear behavior of the composites. The simulated results agreed well with the experimental data. Simultaneously, a theoretical method was developed to predict the shear modulus. By comparing with the experimental data, the accuracy of the theoretical method was verified. The influence of structural parameters on shear modulus was also discussed. The higher yarn number, yarn density and dip angle of the piles could all improve the shear modulus of 3D woven hollow integrated sandwich composites at different levels, while the increasing height would decrease the shear modulus.

  15. Ownership and Determinants Capital Structure of Public Listed Companies in Indonesia: a Panel Data Analysis

    Directory of Open Access Journals (Sweden)

    Arief Tri Hardiyanto

    2013-04-01

    Full Text Available Capital structure is a mix of debts and equities used by a company to finance its investment. Debt offers benefit of tax shield from interest expenses that can be deducted in calculating company income tax. Unfortunately, company can not use debts in unlimited amount because it will lead to risk of bankcrupt. Therefore, company needs to establish a target (unobserved capital structure which will optimize the value of the firm. The purpose of this study is to investigate the determinant of capital structure and ownership in public listed companies in Indonesia Stock Exchange using Time-Series CrossSection Regression (TSCSREG and supported with a balanced panel data. Data used are financial statements of 228 public listed companies from group of eight industry sectors. Research finding confirms that tax shield and fixed financial burden are significantly influence the capital structure and state ownership also significantly influence the capital structure of the state owned enterprises.

  16. Effects of Various Blowout Panel Configurations on the Structural Response of LANL Building 16-340 to Internal Explosions

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, Jason P. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

    2005-09-01

    The risk of accidental detonation is present whenever any type of high explosives processing activity is performed. These activities are typically carried out indoors to protect processing equipment from the weather and to hide possibly secret processes from view. Often, highly strengthened reinforced concrete buildings are employed to house these activities. These buildings may incorporate several design features, including the use of lightweight frangible blowout panels, to help mitigate blast effects. These panels are used to construct walls that are durable enough to withstand the weather, but are of minimal weight to provide overpressure relief by quickly moving outwards and creating a vent area during an accidental explosion. In this study the behavior of blowout panels under various blast loading conditions was examined. External loadings from explosions occurring in nearby rooms were of primary interest. Several reinforcement systems were designed to help blowout panels resist failure from external blast loads while still allowing them to function as vents when subjected to internal explosions. The reinforcements were studied using two analytical techniques, yield-line analysis and modal analysis, and the hydrocode AUTODYN. A blowout panel reinforcement design was created that could prevent panels from being blown inward by external explosions. This design was found to increase the internal loading of the building by 20%, as compared with nonreinforced panels. Nonreinforced panels were found to increase the structural loads by 80% when compared to an open wall at the panel location.

  17. Ni Foam-Ni3 S2 @Ni(OH)2 -Graphene Sandwich Structure Electrode Materials: Facile Synthesis and High Supercapacitor Performance.

    Science.gov (United States)

    Wang, Xiaobing; Hu, Jiangjiang; Su, Yichang; Hao, Jin; Liu, Fanggang; Han, Shuang; An, Jian; Lian, Jianshe

    2017-03-23

    A novel Ni foam-Ni3 S2 @Ni(OH)2 -graphene sandwich-structured electrode (NF-NN-G) with high areal mass loading (8.33 mg cm(-2) ) has been developed by sulfidation and hydrolysis reactions. The conductivity of Ni3 S2 and Ni(OH)2 were both improved. The upper layer of Ni(OH)2 , covered with a thin graphene film, is formed in situ from the surface of the lower layer of Ni3 S2 , whereas the Ni3 S2 grown on Ni foam substrate mainly acts as a rough support bridging the Ni(OH)2 and Ni foam. The graphene stabilized the Ni(OH)2 and the electrochemical properties were effectively enhanced. The as-synthesized NF-NN-G-5mg electrode shows a high specific capacitance (2258 F g(-1) at 1 A g(-1) or 18.81 F cm(-2) at 8.33 mA cm(-2) ) and an outstanding rate property (1010 F g(-1) at 20 Ag(-1) or 8.413 F cm(-2) at 166.6 mA cm(-2) ). This result is around double the capacitance achieved in previous research on Ni3 S2 @Ni(OH)2 /3DGN composites (3DGN=three-dimensional graphene network). In addition, the as-fabricated NF-NN-G-5mg composite electrode has an excellent cycle life with no capacitance loss after 3000 cycles, indicating a potential application as an efficient electrode. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Mechanical and vibro-acoustic aspects of composite sandwich cylinders

    NARCIS (Netherlands)

    Yuan, C.

    2013-01-01

    Designing a fuselage involves many considerations such as strength and stability, fatigue, damage tolerance, fire and lightning resistance, thermal and acoustic insulation, production, inspection, maintenance and repair. In the background of the application of composite sandwich structures on the

  19. Half-sandwich ruthenium, rhodium and iridium complexes of ...

    Indian Academy of Sciences (India)

    sandwich ruthenium, rhodium and iridium complexes of triazolopyridine ligand: Synthesis and structural studies. NARASINGA RAO PALEPU RAO MOHAN KOLLIPARA. Regular Article Volume 129 Issue 2 February 2017 pp 177-184 ...

  20. Elastic stability of superplastically formed/diffusion-bonded orthogonally corrugated core sandwich plates

    Science.gov (United States)

    Ko, W. L.

    1980-01-01

    The paper concerns the elastic buckling behavior of a newly developed superplastically formed/diffusion-bonded (SPF/DB) orthogonally corrugated core sandwich plate. Uniaxial buckling loads were calculated for this type of sandwich plate with simply supported edges by using orthotropic sandwich plate theory. The buckling behavior of this sandwich plate was then compared with that of an SPF/DB unidirectionally corrugated core sandwich plate under conditions of equal structural density. It was found that the buckling load for the former was considerably higher than that of the latter.

  1. Experimental Study of the Bending Properties and Deformation Analysis of Web-Reinforced Composite Sandwich Floor Slabs with Four Simply Supported Edges.

    Science.gov (United States)

    Qi, Yujun; Fang, Hai; Liu, Weiqing

    2016-01-01

    Web-reinforced composite sandwich panels exhibit good mechanical properties in one-way bending, but few studies have investigated their flexural behavior and deformation calculation methods under conditions of four simply supported edges. This paper studies the bending performance of and deformation calculation methods for two-way web-reinforced composite sandwich panels with different web spacing and heights. Polyurethane foam, two-way orthogonal glass-fiber woven cloth and unsaturated resin were used as raw materials in this study. Vacuum infusion molding was used to prepare an ordinary composite sandwich panel and 5 web-reinforced composite sandwich panels with different spacing and web heights. The panels were subjected to two-way panel bending tests with simple support for all four edges. The mechanical properties of these sandwich panels during the elastic stage were determined by applying uniformly distributed loads. The non-linear mechanical characteristics and failure modes were obtained under centrally concentrated loading. Finally, simulations of the sandwich panels, which used the mechanical model established herein, were used to deduce the formulae for the deflection deformation for this type of sandwich panel. The experimental results show that webs can significantly improve the limit bearing capacity and flexural rigidity of sandwich panels, with smaller web spacing producing a stronger effect. When the web spacing is 75 mm, the limit bearing capacity is 4.63 times that of an ordinary sandwich panel. The deduced deflection calculation formulae provide values that agree well with the measurements (maximum error design of this type of panel.

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

    Science.gov (United States)

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

    2010-03-01

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

  3. Design and test of lightweight sandwich T-joint for naval ships

    DEFF Research Database (Denmark)

    Toftegaard, H.; Lystrup, Aa.

    2005-01-01

    -joint with reduced weight but with the same or higher strength than the existing design. The lightweight T-joint is designed for sandwich panels with 60 mm thick PVC foam core and 4 rum thick glass fibre/vinyl ester skin laminates. The panels are joined by use of filler and two triangular PVC foam fillets (core...... of panels joined by filler and overlaminates of the same thickness as the skin laminates. Various improved T-joints have been designed and investigated. Some with focus on improved strength (survivability), and others with focus on reduced weight. This paper describes the design and test of a sandwich T...

  4. Development of a hemodialysis safety checklist using a structured panel process.

    Science.gov (United States)

    Silver, Samuel A; Thomas, Alison; Rathe, Andrea; Robinson, Pamela; Wald, Ron; Harel, Ziv; Bell, Chaim M

    2015-01-01

    The World Health Organization created a Surgical Safety Checklist with a pause or "time out" to help reduce preventable adverse events and improve communication. A similar tool might improve patient safety and reduce treatment-associated morbidity in the hemodialysis unit. To develop a Hemodialysis Safety Checklist (Hemo Pause) for daily use by nurses and patients. A modified Delphi consensus technique based on the RAND method was used to evaluate and revise the checklist. University-affiliated in-center hemodialysis unit. A multidisciplinary team of physicians, nurses, and administrators developed the initial version of the Hemo Pause Checklist. The evaluation team consisted of 20 registered hemodialysis nurses. The top 5 hemodialysis safety measures according to hemodialysis nurses. A 75% agreement threshold was required for consensus. The structured panel process was iterative, consisting of a literature review to identify safety parameters, individual rating of each parameter by the panel of hemodialysis nurses, an in-person consensus meeting wherein the panel refined the parameters, and a final anonymous survey that assessed panel consensus. The literature review produced 31 patient safety parameters. Individual review by panelists reduced the list to 25 parameters, followed by further reduction to 19 at the in-person consensus meeting. The final round of scoring yielded the following top 5 safety measures: 1) confirmation of patient identity, 2) measurement of pre-dialysis weight, 3) recognition and transcription of new medical orders, 4) confirmation of dialysate composition based on prescription, and 5) measurement of pre-dialysis blood pressure. Revision using human factors principles incorporated the 19 patient safety parameters with greater than or equal to 75% consensus into a final checklist of 17-items. The literature review was not systematic. This was a single-center study, and the panel lacked patient and family representation. A novel 17-item

  5. Finite element simulation of low velocity impact loading on a sandwich composite

    OpenAIRE

    Vishwas M.; Joladarashi Sharnappa; Kulkarni Satyabodh M.

    2018-01-01

    Sandwich structure offer more advantage in bringing flexural stiffness and energy absorption capabilities in the application of automobile and aerospace components. This paper presents comparison study and analysis of two types of composite sandwich structures, one having Jute Epoxy skins with rubber core and the other having Glass Epoxy skins with rubber core subjected to low velocity normal impact loading. The behaviour of sandwich structure with various parameters such as energy absorption...

  6. Panel Data with Cross-Sectional Dependence Characterized by a Multi-Level Factor Structure

    DEFF Research Database (Denmark)

    Rodríguez-Caballero, Carlos Vladimir

    A panel data model with a multi-level cross-sectional dependence is proposed. The factor structure is driven by top-level common factors as well as non-pervasive factors. I propose a simple method to filter out the full factor structure that overcomes limitations in standard procedures which may...... mix up both levels of unobservable factors and may hamper the identification of the model. The model covers both stationary and non-stationary cases and takes into account other relevant features that make the model well suited to the analysis of many types of time series frequently addressed...... in macroeconomics and finance. The model makes it possible to examine the time series and cross-sectional dynamics of variables allowing for a rich fractional cointegration analysis. A Monte Carlo simulation is conducted to examine the finite sample features of the suggested procedure. Findings indicate...

  7. Computational Simulation of VARI Fluid Process Molding for Stiffened Panel Structural Composites

    Directory of Open Access Journals (Sweden)

    XIAO Fei

    2016-08-01

    Full Text Available The resin filling time can be predicted and the flow pattern of resin can be simulated in Composites VARI Fluid Process Molding with simulation software PAM-RTM. The permeability is important parameter in VARI process. In-plane and transverse permeability are usually tested with complicate and expensive enclosed mold.A set of model with simple structure, easy operation, low cost, was built to obtain accurate permeability by using a process of vacuum-assisted resin infusion (VARI. Besides, the method of equivalent model was employed. The simulation results of effective model is compared with those of experimental VARI process. The filling times for simulation method is 254 s which is shorter than 301 s of the experimental process. Based on flow runner project with equivalent model, the stiffened panel structural composite is prepared to validate the selective process.

  8. Simple Stiffness Tailoring of Balsa Sandwich Core Material

    OpenAIRE

    Kepler, J.A.

    2010-01-01

    Abstract A concept for improving the shear stiffness properties of balsa core material for sandwich structures is presented. The concept is based on utilization of the strongly orthotropic properties of the balsa wood, applying an appropriate transverse layup sequence. The effective core material shear modulus is modeled using basic laminate theory. This is subsequently validated through sandwich beam bending and lap shear experiments. Compared to the standard balsa core systems, a...

  9. Use of a structured panel process to define quality metrics for antimicrobial stewardship programs.

    Science.gov (United States)

    Morris, Andrew M; Brener, Stacey; Dresser, Linda; Daneman, Nick; Dellit, Timothy H; Avdic, Edina; Bell, Chaim M

    2012-05-01

    Antimicrobial stewardship programs are being implemented in health care to reduce inappropriate antimicrobial use, adverse events, Clostridium difficile infection, and antimicrobial resistance. There is no standardized approach to evaluate the impact of these programs. To use a structured panel process to define quality improvement metrics for evaluating antimicrobial stewardship programs in hospital settings that also have the potential to be used as part of public reporting efforts. A multiphase modified Delphi technique. Paper-based survey supplemented with a 1-day consensus meeting. A 10-member expert panel from Canada and the United States was assembled to evaluate indicators for relevance, effectiveness, and the potential to aid quality improvement efforts. There were a total of 5 final metrics selected by the panel: (1) days of therapy per 1000 patient-days; (2) number of patients with specific organisms that are drug resistant; (3) mortality related to antimicrobial-resistant organisms; (4) conservable days of therapy among patients with community-acquired pneumonia (CAP), skin and soft-tissue infections (SSTI), or sepsis and bloodstream infections (BSI); and (5) unplanned hospital readmission within 30 days after discharge from the hospital in which the most responsible diagnosis was one of CAP, SSTI, sepsis or BSI. The first and second indicators were also identified as useful for accountability purposes, such as public reporting. We have successfully identified 2 measures for public reporting purposes and 5 measures that can be used internally in healthcare settings as quality indicators. These indicators can be implemented across diverse healthcare systems to enable ongoing evaluation of antimicrobial stewardship programs and complement efforts for improved patient safety.

  10. Volatile organic chemical emissions from structural insulated panel (SIP) materials and implications for indoor air quality

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, Alfred T.

    2003-09-01

    The emissions of volatile organic compounds (VOCs) from structural insulated panel (SIP) materials were investigated. Specimens of newly produced SIPs and associated panel adhesives were obtained from two relatively large manufacturers. Additionally, specimens of the oriented strand board (OSB) used as the inner and outer sheathing and the extruded polystyrene core for the SIP were obtained from one manufacturer. Using small-scale chambers, emissions of formaldehyde, acetaldehyde, acetic acid and other VOCs from SIPs, OSB and polystyrene were measured over a period of four months and from the adhesives over two months. SIP specimens overlaid by gypsum board panels were also tested over four months. The predominant VOCs emitted by the SIPs included acetic acid, pentanal, hexanal and styrene. The emissions of formaldehyde and acetaldehyde were relatively low. Acetic acid and the aldehydes derived from the OSB, while styrene derived from the polystyrene. One of the SIPs emitted toluene and methyl acetate. The adhesives primarily emitted a mixture of hydrocarbons. The emission rates of most VOCs from the SIP/gypsum board assemblies were approximately the same or higher than their respective emission rates from the unfinished SIPs. Modeling using VOC emission factors obtained for the SIP/gypsum board assemblies demonstrated the potential for SIP materials to degrade indoor air quality in houses. A field study to investigate VOC concentrations and emission rates in SIP houses relative to closely matched conventionally constructed houses is necessary to determine the actual impacts of SIPs. If significant impacts are observed, to it may be desirable to develop control measures to reduce the emissions of VOCs from SIPs, such as the substitution of lower emitting materials or the use of vapor diffusion barriers.

  11. Structure, Mechanism, and Application of Vacuum Insulation Panels in Chinese Buildings

    Directory of Open Access Journals (Sweden)

    Changhai Peng

    2016-01-01

    Full Text Available Thermal insulation is one of the most used approaches to reduce energy consumption in buildings. Vacuum insulation panels (VIPs are new thermal insulation materials that have been used in the domestic and overseas market in the last 20 years. Due to the vacuum thermal insulation technology of these new materials, their thermal conductivity can be as low as 0.004 W/(m·K at the center of panels. In addition, VIPs that are composites with inorganic core and an envelope out of commonly three metallized PET layers and a PE sealing layer can provide B class fire resistance (their core materials are not flammable and are classified as A1. Compared with other conventional thermal insulation materials, the thermal insulation and fire resistance performances form the foundation of VIP’s applications in the construction industry. The structure and thermal insulation mechanism of VIP and their application potential and problems in Chinese buildings are described in detail.

  12. Characterization of Linkage Disequilibrium and Population Structure in a Mungbean Diversity Panel

    Directory of Open Access Journals (Sweden)

    Thomas J. Noble

    2018-01-01

    Full Text Available Mungbean [Vigna radiata (L. R. Wilczek var. radiata] is an important grain legume globally, providing a high-quality plant protein source largely produced and consumed in South and East Asia. This study aimed to characterize a mungbean diversity panel consisting of 466 cultivated accessions and demonstrate its utility by conducting a pilot genome-wide association study of seed coat color. In addition 16 wild accessions were genotyped for comparison and in total over 22,000 polymorphic genome-wide SNPs were identified and used to analyze the genetic diversity, population structure, linkage disequilibrium (LD of mungbean. Polymorphism was lower in the cultivated accessions in comparison to the wild accessions, with average polymorphism information content values 0.174, versus 0.305 in wild mungbean. LD decayed in ∼100 kb in cultivated lines, a distance higher than the linkage decay of ∼60 kb estimated in wild mungbean. Four distinct subgroups were identified within the cultivated lines, which broadly corresponded to geographic origin and seed characteristics. In a pilot genome-wide association mapping study of seed coat color, five genomic regions associated were identified, two of which were close to seed coat color genes in other species. This mungbean diversity panel constitutes a valuable resource for genetic dissection of important agronomical traits to accelerate mungbean breeding.

  13. Design, fabrication, and test of lightweight shell structure. [for application to the space tug design

    Science.gov (United States)

    1974-01-01

    A cylindrical shell skirt structure was subjected to a design and analysis study using a wide variety of structural materials and concepts. The design loading, axial compression, and torsion is representative of that expected on a typical space tug skirt section. Structural concepts evaluated included honeycomb sandwich, truss, isogrid, and skin/stringer/frame. The materials considered included a wide variety of structural metals as well as glass, graphite, and boron-reinforced composites. Honeycomb sandwich with aluminum faceskins, honeycomb sandwich with graphite/epoxy faceskins, and aluminum truss with fiberglass meteoroid protection layers were the designs selected for further evaluation. Procurement of materials required for fabrication is reported and the structural test plan and fabrication drawings are included. Construction of the graphite/epoxy faceskins, chem mill of the aluminum faceskins, chem mill of aluminum truss components, and fabrication of the graphite/epoxy honeycomb sandwich development panel is also reported.

  14. Rheological behaviour and thermal dilation effects of alumino-silicate adhesives intended for joining of high-temperature resistant sandwich structures

    Czech Academy of Sciences Publication Activity Database

    Černý, Martin; Chlup, Zdeněk; Strachota, Adam; Schweigstillová, Jana; Svítilová, Jaroslava; Halasová, Martina

    2017-01-01

    Roč. 37, č. 5 (2017), s. 2209-2218 ISSN 0955-2219 R&D Projects: GA ČR GAP107/12/2445 Grant - others:OPPK(XE) CZ.2.16/3.1.00/21538 Program:OPPK Institutional support: RVO:67985891 ; RVO:68081723 ; RVO:61389013 Keywords : Sandwich * Inorganic adhesive * Si-O-C ceramics * Ceramic foam * Ceramic fibre Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass; CD - Macromolecular Chemistry (UMCH-V); JH - Ceramics, Fire-Resistant Materials and Glass (UFM-A) OBOR OECD: Polymer science (UMCH-V) Impact factor: 3.411, year: 2016

  15. Bending Characteristics of Foldable Touch Display Panel with a Protection Structure Design

    Directory of Open Access Journals (Sweden)

    Hsien-Chie Cheng

    2015-01-01

    Full Text Available The study proposes and demonstrates an enhancement of a touch display panel (TDP through a polymer-based protection structure to achieve higher bendability and reliability. The bending performance of the TDP without or with the protection structure designs is addressed using three-dimensional geometry-nonlinear finite element analysis and mechanical testing. The elastic properties of the components in the TDP structure are derived from nanoindentation and uniaxial tensile/compressive testing. The calculated results are compared with each other and also against the experimental bending fatigue test data. At last, a design guideline and optimal factor setting for enhanced bending performance are sought through parametric FE analysis and Taguchi experimental design, respectively. The optimal design is compared with the original in terms of bending stress. The simulation results show that bending would create significant tensile and compressive bending stresses on the indium tin oxide/dielectric layers, which are the main cause of several commonly observed failures, such as thin film cracking and delamination, in a thin rigid film coating on a thick compliant substrate. It also turns out that a substrate with a lower stiffness has a better mechanical stability against bending stress.

  16. Structural Stability of a Stiffened Aluminum Fuselage Panel Subjected to Combined Mechanical and Internal Pressure Loads

    Science.gov (United States)

    Rouse, Marshall; Young, Richard D.; Gehrki, Ralph R.

    2003-01-01

    Results from an experimental and analytical study of a curved stiffened aluminum panel subjected to combined mechanical and internal pressure loads are presented. The panel loading conditions were simulated using a D-box test fixture. Analytical buckling load results calculated from a finite element analysis are presented and compared to experimental results. Buckling results presented indicate that the buckling load of the fuselage panel is significantly influenced by internal pressure loading. The experimental results suggest that the stress distribution is uniform in the panel prior to buckling. Nonlinear finite element analysis results correlates well with experimental results up to buckling.

  17. Vibroacoustic Model Validation for a Curved Honeycomb Composite Panel

    Science.gov (United States)

    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.

  18. A new rate-dependent unidirectional composite model - Application to panels subjected to underwater blast

    Science.gov (United States)

    Wei, Xiaoding; de Vaucorbeil, Alban; Tran, Phuong; Espinosa, Horacio D.

    2013-06-01

    In this study, we developed a finite element fluid-structure interaction model to understand the deformation and failure mechanisms of both monolithic and sandwich composite panels. A new failure criterion that includes strain-rate effects was formulated and implemented to simulate different damage modes in unidirectional glass fiber/matrix composites. The laminate model uses Hashin's fiber failure criterion and a modified Tsai-Wu matrix failure criterion. The composite moduli are degraded using five damage variables, which are updated in the post-failure regime by means of a linear softening law governed by an energy release criterion. A key feature in the formulation is the distinction between fiber rupture and pull-out by introducing a modified fracture toughness, which varies from a fiber tensile toughness to a matrix tensile toughness as a function of the ratio of longitudinal normal stress to effective shear stress. The delamination between laminas is modeled by a strain-rate sensitive cohesive law. In the case of sandwich panels, core compaction is modeled by a crushable foam plasticity model with volumetric hardening and strain-rate sensitivity. These constitutive descriptions were used to predict deformation histories, fiber/matrix damage patterns, and inter-lamina delamination, for both monolithic and sandwich composite panels subjected to underwater blast. The numerical predictions were compared with experimental observations. We demonstrate that the new rate dependent composite damage model captures the spatial distribution and magnitude of damage significantly more accurately than previously developed models.

  19. Application of Structured Light System Technique for Authentication of Wooden Panel Paintings

    Directory of Open Access Journals (Sweden)

    Fernando Buchón-Moragues

    2016-06-01

    Full Text Available This paper presents a new application of photogrammetric techniques for protecting cultural heritage. The accuracy of the method and the fact that it can be used to carry out different tests without contact between the sample and the instruments can make this technique very useful for authenticating and cataloging artworks. The application focuses on the field of pictorial artworks, and wooden panel paintings in particular. In these works, the orography formed by the brushstrokes can be easily digitalized using a photogrammetric technique, called Structured Light System, with submillimeter accuracy. Thus, some of the physical characteristics of the brushstrokes, like minimum and maximum heights or slopes become a fingerprint of the painting. We explain in detail the general principles of the Structured Light System Technique and the specific characteristics of the commercial set-up used in this work. Some experiments are carried out on a sample painted by us to check the accuracy limits of the technique and to propose some tests that can help to stablish a methodology for authentication purposes. Finally, some preliminary results obtained on a real pictorial artwork are presented, providing geometrical information of its metric features as an example of the possibilities of this application.

  20. Application of Structured Light System Technique for Authentication of Wooden Panel Paintings

    Science.gov (United States)

    Buchón-Moragues, Fernando; Bravo, José María; Ferri, Marcelino; Redondo, Javier; Sánchez-Pérez, Juan Vicente

    2016-01-01

    This paper presents a new application of photogrammetric techniques for protecting cultural heritage. The accuracy of the method and the fact that it can be used to carry out different tests without contact between the sample and the instruments can make this technique very useful for authenticating and cataloging artworks. The application focuses on the field of pictorial artworks, and wooden panel paintings in particular. In these works, the orography formed by the brushstrokes can be easily digitalized using a photogrammetric technique, called Structured Light System, with submillimeter accuracy. Thus, some of the physical characteristics of the brushstrokes, like minimum and maximum heights or slopes become a fingerprint of the painting. We explain in detail the general principles of the Structured Light System Technique and the specific characteristics of the commercial set-up used in this work. Some experiments are carried out on a sample painted by us to check the accuracy limits of the technique and to propose some tests that can help to stablish a methodology for authentication purposes. Finally, some preliminary results obtained on a real pictorial artwork are presented, providing geometrical information of its metric features as an example of the possibilities of this application. PMID:27314353

  1. Carbon Mitigation Impacts of Increased Softwood Lumber and Structural Panel Use for Nonresidential Construction in the United States

    Science.gov (United States)

    Prakash Nepal; Kenneth E. Skog; David B. McKeever; Richard D. Bergman; Karen L. Abt; Robert C. Abt

    2016-01-01

    More wood use in the United States to construct low-rise nonresidential (NR) buildings would increase consumption and production of softwood (SW) lumber, engineered wood products, and structural and nonstructural wood panels. Using a consequential life-cycle analysis, we estimated the change in net CO2 emissions thatwould be caused by increased...

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

    Science.gov (United States)

    Nicole M. Stark; Zhiyong Cai; Charles Carll

    2010-01-01

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

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

    Science.gov (United States)

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

    2012-01-01

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

  4. Impact damage analysis of balsawood sandwich composite materials

    Science.gov (United States)

    Abdalslam, Suof Omran

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

  5. Facesheet Delamination of Composite Sandwich Materials at Cryogenic Temperatures

    Science.gov (United States)

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

    2003-01-01

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

  6. Evaluation of Thin Kevlar-Epoxy Fabric Panels Subjected to Shear Loading

    Science.gov (United States)

    Baker, Donald J.

    1996-01-01

    The results of an analytical and experimental investigation of 4-ply Kevlar-49-epoxy panels loaded by in-plane shear are presented. Approximately one-half of the panels are thin-core sandwich panels and the other panels are solid-laminate panels. Selected panels were impacted with an aluminum sphere at a velocity of either 150 or 220 ft/sec. The strength of panels impacted at 150 ft/sec was not reduced when compared to the strength of the undamaged panels, but the strength of panels impacted at 220 ft/sec was reduced by 27 to 40 percent. Results are presented for panels that were cyclically loaded from a load less than the buckling load to a load in the postbuckling load range. The thin-core sandwich panels had a lower fatigue life than the solid panels. The residual strength of the solid and sandwich panels cycled more than one million cycles exceeded the baseline undamaged panel strengths. The effect of hysteresis in the response of the sandwich panels is not significant. Results of a nonlinear finite element analysis conducted for each panel design are presented.

  7. Numerical computation of motions and structural loads for large containership using 3D Rankine panel method

    Science.gov (United States)

    Kim, Jung-Hyun; Kim, Yonghwan

    2017-12-01

    In this paper, we present the results of our numerical seakeeping analyses of a 6750-TEU containership, which were subjected to the benchmark test of the 2nd ITTC-ISSC Joint Workshop held in 2014. We performed the seakeeping analyses using three different methods based on a 3D Rankine panel method, including 1) a rigid-body solver, 2) a flexible-body solver using a beam model, and 3) a flexible-body solver using the eigenvectors of a 3D Finite Element Model (FEM). The flexible-body solvers adopt a fully coupled approach between the fluid and structure. We consider the nonlinear Froude-Krylov and restoring forces using a weakly nonlinear approach. In addition, we calculate the slamming loads on the bow flare and stern using a 2D generalized Wagner model. We compare the numerical and experimental results in terms of the linear response, the time series of the nonlinear response, and the longitudinal distribution of the sagging and hogging moments. The flexible-body solvers show good agreement with the experimental model with respect to both the linear and nonlinear results, including the high-frequency oscillations due to springing and whipping vibrations. The rigid-body solver gives similar results except for the springing and whipping.

  8. Experimental Study for Structural Behaviour of Precast Lightweight Panel (PLP) Under Flexural Load

    Science.gov (United States)

    Goh, W. I.; Mohamad, N.; Tay, Y. L.; Rahim, N. H. A.; Jhatial, A. A.; Samad, A. A. A.; Abdullah, R.

    2017-06-01

    Precast lightweight concrete slab is first fabricated in workshop or industrial before construction and then transported to site and installed by skilled labour. It can reduce construction time by minimizing user delay and time for cast-in-situ to increase workability and efficiency. is environmental friendly and helps in resource reduction. Although the foamed concrete has low compressive strength compared to normal weight concrete but it has excellent thermal insulation and sound absorption. It is environmental friendly and helps in resource reduction. To determine the material properties of foamed concrete, nine cubes and six cylindrical specimens were fabricated and the results were recorded. In this study, structural behaviour of precast lightweight panel (PLP) with dry density of 1800 kg/m3 was tested under flexural load. The results were recorded and analysed in terms of ultimate load, crack pattern, load-deflection profiles and strain distribution. Linear Voltage Displacement Transducers (LVDT) and strain gauges were used to determine the deflection and strain distribution of PLP. The theoretical and experimental ultimate load of PLP was analysed and recorded to be 70 and 62 kN respectively, having a difference of 12.9%. Based on the results, it can be observed that PLP can resist the adequate loading. Thus, it can be used in precast industry for construction purposes.

  9. Impact damage and residual strength analysis of composite panels with bonded stiffeners. [for primary aircraft structures

    Science.gov (United States)

    Madan, Ram C.; Shuart, Mark J.

    1990-01-01

    Blade-stiffened, compression-loaded cover panels were designed, manufactured, analyzed, and tested. All panels were fabricated from IM6/1808I interleafed graphite-epoxy. An orthotropic blade stiffener and an orthotropic skin were selected to satisfy the design requirements for an advanced aircraft configuration. All specimens were impact damaged prior to testing. Experimental results were obtained for three- and five-stiffener panels. Analytical results described interlaminar forces caused by impact and predicted specimen residual strength. The analytical results compared reasonably with the experimental results for residual strength of the specimens.

  10. Pulsed terahertz inspection of non-conducting sandwich composites

    Science.gov (United States)

    Lopato, P.; Chady, T.

    2013-01-01

    Pulsed terahertz inspection enables accurate, contactless and safe for operating personnel evaluation of non-conducting structures. In this paper we present results of pulsed terahertz testing of various sandwich composite structures incorporating glass and basalt fibers based skin materials and spherecore and balsa wood based core materials. Various Time-Frequency Distributions (TFD) are utilized in order to obtain most valuable defects response.

  11. Quantum confinement in multi-nanolayer sandwich systems

    Science.gov (United States)

    Khmelinskii, Igor; Makarov, Vladimir I.

    2017-11-01

    Presently we explored quantum confinement (QC) in three-nanolayer sandwich systems, composed of Au-SnO2-Fe, Au-SnO2-Si and Au-SnO2-Ag layers. We recorded the absorption spectra of these sandwich systems, all with discrete structure. We recorded the action spectra of the photocurrent for the Au-SnO2-Fe sandwich system, with the photocurrent quantum yields increasing with the photon energy, achieving 3.1 at 4.7 × 104 cm-1. The photocurrent action spectra correlate with high accuracy with optical absorption spectra. We discuss the mechanisms determining the absorption bandwidth value, including surface imperfections, thermal distribution of the vibrational level populations in the electronic ground state, and the diabatic coupling of levels of the excited state to those of a ;dark; state. Volt-Ampere (V/A) characteristics were recorded for all three of the sandwich systems, quite similar to those of a Schottky diode. We report the parameter values of the V/A characteristics, found by fitting the experimental data with a theoretical curve. We also report charge density changes in the SnO2 layer caused by low constant voltage applied to the sandwich structure, observed as changes in the absorption band intensity.

  12. Population Structure and Phylogenetic Relationships in a Diverse Panel of Brassica rapa L.

    Science.gov (United States)

    Bird, Kevin A.; An, Hong; Gazave, Elodie; Gore, Michael A.; Pires, J. Chris; Robertson, Larry D.; Labate, Joanne A.

    2017-01-01

    The crop species Brassica rapa L. has significant economic importance around the world. However, the global distribution and complex evolutionary history of the species has made investigating its genetic population structure difficult. Crop domestication and improvement has resulted in extreme phenotypic diversity and subspecies that are used for oilseed, food for human consumption, and fodder for livestock. These subspecies include the oilseed morphotypes. oleifera (turnip rape), ssp. dichotoma (brown sarson/toria), ssp. trilocularis (yellow sarson); ssp. rapa (turnip); and Asian leafy vegetables ssp. pekinensis (Chinese cabbage), ssp. chinensis (bok choy), ssp. nipposinica (mizuna/mibuna), ssp. rapifera (rapini/broccoli rabe), ssp. narinosa (tatsoi), ssp parachinensis (choy sum), and ssp. perviridis (komatsuna). To date, studies have had insufficient sampling to determine the relationship of all morphotypes, especially oilseed morphotypes, and questions remain over the contribution of morphotype and geographic origin to population structure. We used genotyping-by-sequencing to score 18,272 single nucleotide polymorphism markers in a globally diverse panel of 333 B. rapa National Plant Germplasm System accessions that included 10 recognized subspecies. Our population genetic and phylogenetic analyses were broadly congruent and revealed five subpopulations that were largely reflective of morphotype and geography. These subpopulations were 1. European turnips/oilseed, 2. Asian turnips/oilseed, 3. yellow/brown sarson (ssp. trilocularis and ssp. dichotoma), 4. Chinese cabbage (ssp. pekinensis), and 5. bok choy, choy sum, and tatsoi (ssp. chinensis, ssp. parachinensis, ssp. narinosa). Additionally, we found evidence of polyphyly and/or paraphyly, particularly for oilseed morphotypes (ssp. oleifera and ssp. dichotoma) and turnips. The results of this study have provided improved resolution to the genetic and phylogenetic relationships of subspecies within the species B

  13. Acoustical and thermal performance of multilayer closing panels used in steel-structured buildings

    Directory of Open Access Journals (Sweden)

    Rovadávia Aline de Jesus Ribas

    Full Text Available Abstract This article provides an evaluation of the acoustical and thermal performance of some closing systems by referencing materials such as cement plates, plasterboard walls, precast concrete panels and expanded polystyrene. Reverberation time is calculated by applying an empirical formula, which uses temperature and relative air humidity values obtained from simulations that were conducted using the computational simulation program ESP-r (Energy Simulation Program-research. The internal temperature presented by the ESP-r is an indicator of thermal performance. Using a simplified graphic method, the acoustical performance is also evaluated by estimating the loss of sound transmission that occurs through the closing panels. Combinations of these panels, which form multilayer panels mediated by a layer of air and with or without insulating material between them, are applied. The results show that multilayered closing systems, when filled with insulating material, are an efficient solution than can provide adequate acoustical and thermal performance.

  14. Capital structure, profitability and firm value: panel evidence of listed firms in Kenya

    OpenAIRE

    Kodongo, Odongo; Mokoaleli-Mokoteli, Thabang; Maina, Leonard

    2014-01-01

    This paper investigates the relationship between leverage and the financial performance of listed firm in Kenya. We use annual data for the period 2002 – 2011. Using various panel procedures, our study finds reasonably strong evidence that leverage significantly, and negatively, affects the profitability of listed firms in Kenya. However, leverage has no effect on Tobin’s Q, our proxy for firm value. Our results are robust to alternative panel specifications and hold for both small-size and l...

  15. Synthetic, reactivity, and structural studies on half-sandwich (eta5-C5Me5)Be and related compounds: halide, alkyl, and iminoacyl derivatives.

    Science.gov (United States)

    del Mar Conejo, M; Fernández, Rafael; Carmona, Ernesto; Andersen, Richard A; Gutiérrez-Puebla, Enrique; Monge, M Angeles

    2003-09-22

    The half-sandwich compounds [(eta(5)-C(5)Me(5))BeX] (X=Cl, 1 a; Br, 1 b), readily prepared from the reaction of the halides BeX(2) and M[C(5)Me(5)] (M=Na or K), are useful synthons for other (eta(5)-C(5)Me(5))Be organometallic compounds, including the alkyl derivatives [(eta(5)-C(5)Me(5))BeR] (R=Me, 2 a; CMe(3), 2 b; CH(2)CMe(3), 2 c; CH(2)Ph, 2 d). The latter compounds can be obtained by metathetical exchange of the halides 1 with the corresponding lithium reagent and exhibit NMR signals and other properties in accord with the proposed formulation. Attempts to make [(eta(5)-C(5)Me(5))BeH] have proved fruitless, probably due to instability of the hydride toward disproportionation into [Be(C(5)Me(5))(2)] and BeH(2). The half-sandwich iminoacyl [(eta(5)-C(5)Me(5))Be(C(NXyl)Cp')] and [(eta(5)-C(5)Me(4)H)Be(C(NXyl)Cp')]3, 6 where Xyl=C(6)H(3)-2,6-Me(2) and Cp'=C(5)Me(5) or C(5)Me(4)H, are formed when the beryllocenes [Be(C(5)Me(5))(2)], [Be(C(5)Me(4)H)(2)], and [Be(C(5)Me(5))(C(5)Me(4)H)] are allowed to react with CNXyl. Isolation of three different iminoacyl isomers from the reaction of the mixed-ring beryllocene [(eta(5)-C(5)Me(5))Be(eta(1)-C(5)Me(4)H)] and CNXyl, namely compounds 5 a, 5 b, and 6, provides compelling evidence for the existence in solution of different beryllocene isomers, generated in the course of two very facile processes that explain the solution dynamics of these metallocenes, that is the 1,5-sigmatropic shift of the Be(eta(5)-Cp') unit around the periphery of the eta(1)-Cp' ring, and the molecular inversion rearrangement that exchanges the roles of the two rings.

  16. Robust and Air-Stable Sandwiched Organo-Lead Halide Perovskites for Photodetector Applications

    KAUST Repository

    Mohammed, Omar F.

    2016-02-25

    We report the simplest possible method to date for fabricating robust, air-stable, sandwiched perovskite photodetectors. Our proposed sandwiched structure is devoid of electron or hole transporting layers and also the expensive electrodes. These simpler architectures may have application in the perovskite-only class of solar cells scaling up towards commercialization.

  17. Highly improved photo-induced bias stability of sandwiched triple layer structure in sol-gel processed fluorine-doped indium zinc oxide thin film transistor

    Directory of Open Access Journals (Sweden)

    Dongha Kim

    2016-03-01

    Full Text Available In order to improve the reliability of TFT, an Al2O3 insulating layer is inserted between active fluorine doped indium zinc oxide (IZO:F thin films to form a sandwiched triple layer. All the thin films were fabricated via low-cost sol-gel process. Due to its large energy bandgap and high bonding energy with oxygen atoms, the Al2O3 layer acts as a photo-induced positive charge blocking layer that effectively blocks the migration of both holes and V o2+ toward the interface between the gate insulator and the semiconductor. The inserted Al2O3 triple layer exhibits a noticeably low turn on voltage shift of −0.7 V under NBIS as well as the good TFT performance with a mobility of 10.9 cm2/V ⋅ s. We anticipate that this approach can be used to solve the stability issues such as NBIS, which is caused by inescapable oxygen vacancies.

  18. Tailoring the Dielectric Layer Structure for Enhanced Performance of Organic Field-Effect Transistors: The Use of a Sandwiched Polar Dielectric Layer

    Directory of Open Access Journals (Sweden)

    Shijiao Han

    2016-07-01

    Full Text Available To investigate the origins of hydroxyl groups in a polymeric dielectric and its applications in organic field-effect transistors (OFETs, a polar polymer layer was inserted between two polymethyl methacrylate (PMMA dielectric layers, and its effect on the performance as an organic field-effect transistor (OFET was studied. The OFETs with a sandwiched dielectric layer of poly(vinyl alcohol (PVA or poly(4-vinylphenol (PVP containing hydroxyl groups had shown enhanced characteristics compared to those with only PMMA layers. The field-effect mobility had been raised more than 10 times in n-type devices (three times in the p-type one, and the threshold voltage had been lowered almost eight times in p-type devices (two times in the n-type. The on-off ratio of two kinds of devices had been enhanced by almost two orders of magnitude. This was attributed to the orientation of hydroxyl groups from disordered to perpendicular to the substrate under gate-applied voltage bias, and additional charges would be induced by this polarization at the interface between the semiconductor and dielectrics, contributing to the accumulation of charge transfer.

  19. Structural concepts for large solar concentrators

    Science.gov (United States)

    Hedgepeth, J. M.; Miller, R. K.

    1986-01-01

    Solar collectors for space use are examined, including both early designs and current concepts. In particular, attention is given to stiff sandwich panels and aluminum dishes as well as inflated and umbrella-type membrane configurations. The Sunflower concentrator is described as an example of a high-efficiency collector. It is concluded that stiff reflector panels are most likely to provide the long-term consistent accuracy necessary for low-orbit operation. A new configuration consisting of a Pactruss backup structure, with identical panels installed after deployment in space, is presented. It is estimated that concentration ratios in excess of 2000 can be achieved with this concept.

  20. Predicting the behaviour of a wide sandwich beam under pressure loading

    NARCIS (Netherlands)

    Davies, P.; Bigourdan, B.; Chaudot, P.; Choqueuse, D.; Ferreira, A.; Karjalainen, J.P.; Hildebrand, M.; Mustakangas, M.; Gaarder, R.; Carli, F.; Straalen, IJ.J. van; Sargent, J.P.; Adams, R.D.; Broughton, J.; Beevers, A.

    2000-01-01

    This paper presents results from analytical and finite elenent modelling of the response of a wide foam core sandwich beam to uniform pressure loading. New tests have been performed using an image analysis system which allows core shear strain mapping. Predicted panel displacenpnts and strains are

  1. Calculation of dynamic stresses in viscoelastic sandwich beams using oma

    DEFF Research Database (Denmark)

    Pelayo, F.; Aenlle, M. L.; Ismael, G.

    2017-01-01

    The mechanical response of sandwich elements with viscoelastic core is time and temperature dependent. Laminated glass is a sandwich element where the mechanical behavior of the glass layers is usually considered linear-elastic material whereas the core is made of an amorphous thermoplastic which...... data. In simple structures, analytical mode shapes can be used alternatively to the numerical ones. In this paper, the dynamic stresses on the glass layers of a laminated glass beam have estimated using the experimental acceleration responses measured at 7 points of the beam, and the experimental mode...

  2. Fracture Characterization of Sandwich Face/Core Interfaces

    DEFF Research Database (Denmark)

    Manca, Marcello

    such result it is important to devise new experimental and analytical techniques to establish the multi-mode fracture characteristics of sandwich plate structures and accordingly develop methods to inhibit defect propagation. This thesis deals with characterization of fracture between face and core...... samples. A number of sandwich materials were tested (GFRP/foam cores and CFRP/Nomex) bothin static and fatigue. A linear elastic fracture mechanics model was used to determine the analyticalexpression of compliance which allowed to calculate automatically the crack length. In combination, a finite element...

  3. Transverse Shear Behavior of a Nomex Core for Sandwich Panels

    Science.gov (United States)

    Nasir, M. A.; Khan, Z.; Farooqi, I.; Nauman, S.; Anas, S.; Khalil, S.; Pasha, A.; Khan, Z.; Shah, M.; Qaiser, H.; Ata, R.

    2015-01-01

    The out-of-plane transverse shear characteristics of a Nomex honeycomb core have been studied. Finite-element analyses were performed to find the equivalent transverse shear moduli of the honeycomb core by using a unit-cell-based modeling approach with account of the orthotropic nature of Nomex paper. The results obtained are compared with those of three theoretical approaches. The differences between the numerical and theoretical results are attributed to the isotropic behavior of the basic core material considered in the theoretical approaches.

  4. Design and Testing of an Active Core for Sandwich Panels

    Science.gov (United States)

    2008-03-01

    easily through adhesive bonds. However, the actuation energy and the actuation strain of PZT material are generally less then that of the shape...of Moving Asymptote ( MMA ) (Svanberg 2002), can be applied to the large scale optimization problem. Mathematically, SIMP uses a nonlinear...typical SIMP formulation the satisfaction of constraints are generally guaranteed, and also because of numerically motivated reasons when employing MMA as

  5. Structural aspects of SAR antenna for Japanese Earth Resources Satellite 1

    Science.gov (United States)

    Mitsuma, H.

    1984-09-01

    Research and development to establish the basic technology of Synthetic Aperture Radar (SAR) for the Japanese Earth Resources Satellite-1 are described. The solar array paddle technologies (honeycomb sandwich panel and deployment mechanism) were applied to the SAR antenna. Structural and mechanical component tests, and thermal distortion tests are discussed.

  6. Adhesion of resin-modified glass-ionomer cements may affect the integrity of tooth structure in the open sandwich technique.

    Science.gov (United States)

    Czarnecka, Beata; Kruszelnicki, Anna; Kao, Anthony; Strykowska, Marta; Nicholson, John W

    2014-12-01

    To study the interfaces between model cavities prepared in teeth and four glass ionomer cements (two conventional and two resin-modified). Ten non-cavitated molars and premolars were used and, in each, two 3mm deep slot preparations were created on opposing sides of the tooth. The teeth were conditioned as appropriate, then restored using the open sandwich technique, using a conventional glass ionomer (Fuji IX, Ketac Molar) or resin modified glass ionomer (Fuji II LC or N100), followed by completion with composite resin. The teeth were then embedded in a transparent acrylic resin and cut parallel to the long axis through both restorations, using a low speed diamond wheel saw. Samples were evaluated using a metallographic light microscope (100×). Three areas were assessed: the axial wall, the axial gingival line angle and the cavo-surface line angle. Bonding was categorized as inadequate or adequate based on the appearance and inadequate bonding was further studied and classified. Data were analysed statistically using the McNamara analysis. The majority of materials failed to make adequate contact with the axial wall, and there were also flaws at the axial/gingival line angle in several samples. By contrast, the cavo-surface line angle was generally soundly filled and the materials showed intimate contact with the tooth surface in this region. The most serious inadequacy, though, was not lack of intimate contact and/or adhesive bond, but the presence of perpendicular cracks in 30% of the Fuji II LC samples which extended into the underlying dentin. The problems of placement and dentin cracking experienced with these materials demonstrate that adhesive bond strength alone cannot be used as the criterion of success for restorative materials. In fact good adhesion can, in certain cases, promote cracking of the dentin due to stresses within the material, an outcome which is undesirable. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All

  7. Detecting Serial Correlation in the Error Structure of a Cross-Lagged Panel Model.

    Science.gov (United States)

    1988-02-02

    11 SWV IvW WV WV and their perception of the quality of care they are receiving from the Health Maintenance Organizacion in which they are enrolled...Kenny, D.A. and Campbell, D.T. (1972) "Does Intelligence Cause Achievement: A Cross-Lagged Panel Analysis", Journal of Educational Psychology , 63, 258-275...Duncan, O.D. (1969) "Some Linear Models for Two-Wave, .Two-Variable Panel Analysis", Psychological Bulletin, 72, 0 177-182. Durbin, J. (1970

  8. Metabolic Panel

    Science.gov (United States)

    A metabolic panel is a group of tests that measures different chemicals in the blood. These tests are usually ... kidneys and liver. There are two types: basic metabolic panel (BMP) and comprehensive metabolic panel (CMP). The ...

  9. Research Status and Action of Sub-millimeter Debris Impact Damage on Spacecraft Structure

    OpenAIRE

    Higashide, Masumi; Kurosaki, Hirohisa; Hasegawa, Sunao; 東出, 真澄; 黒崎, 裕久; 長谷川, 直

    2015-01-01

    To assess debris impact risk for the satellite, submillimeter debris impact damage has not been investigated enough to conduct satellite protective designing. JAXA is researching vulnerability of satellite structure materials against submillimeter debris impact, and proposing shielding methods. This report shows summary of submillimeter impact damages of honeycomb sandwich panels. The damage of the panel was investigated by hypervelocity impact experiments with the two-stage light gas gun in ...

  10. Nurse managers and the sandwich support model.

    Science.gov (United States)

    Chisengantambu, Christine; Robinson, Guy M; Evans, Nina

    2017-09-15

    To explore the interplay between the work of nurse managers and the support they receive and provide. Support is the cornerstone of management practices and is pivotal in employees feeling committed to an organisation. Support for nurse managers is integral to effective health sector management; its characteristics merit more attention. The experiences of 15 nurse managers in rural health institutions in South Australia were explored using structured interviews, observation and document review. Effective decision making requires adequate support, which influences the perceptions and performance of nurse managers, creating an environment in which they feel appreciated and valued. An ideal support system is proposed, the "sandwich support model," to promote effective functioning and desirable patient outcomes via support "from above" and "from below." The need to support nurse managers effectively is crucial to how they function. The sandwich support model can improve management practices, more effectively assisting nurse managers. Organisations should revisit and strengthen support processes for nurse managers to maximize efficiencies. This paper contributes to understanding the importance of supporting nurse managers, identifying the processes used and the type of support offered. It highlights challenges and issues affecting support practices within the health sector. © 2017 John Wiley & Sons Ltd.

  11. Microtomography with a sandwich detector for mouse bone imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seung Ho; Kim, Junwoo; Kim, Ho Kyung [Pusan National University, Busan (Korea, Republic of); Youn, Hanbean; Jeon, Hosang [Pusan National University Yangsan Hospital, Yangsan (Korea, Republic of)

    2015-10-15

    Single-shot dual-energy imaging, using sandwich detector, the rear detector usually uses a thicker x-ray converter to enhance quantum efficiency with the higher-energy spectrum, hence providing a blurrier image than the front detector. The weighted logarithmic subtraction of the two images therefore results in a form of unsharp masking that enhances edges in the resultant image. Inspired by this observation, we have developed a micro computed tomography (micro-CT) system with the sandwich detector for high-resolution bone imaging of small animals. The sandwich detector consists of two flat-panel detectors by stacking one upon the other. Although the x-ray beam continuously irradiates, the step-rotation of an object and stay-readout of projection data were considered for the scanning and data gathering. It will be necessary that more elaborate experiments with the mouse and/or other quantitative phantoms. And quantification of the image quality of bone-enhanced images in comparisons with the conventional images will be performed. The image analysis of differences between bone-enhanced images obtained from the projection- and image-based approaches can be performed.

  12. Standard practice for acoustic emission examination of plate-like and flat panel composite structures used in aerospace applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers acoustic emission (AE) examination or monitoring of panel and plate-like composite structures made entirely of fiber/polymer composites. 1.2 The AE examination detects emission sources and locates the region(s) within the composite structure where the emission originated. When properly developed AE-based criteria for the composite item are in place, the AE data can be used for nondestructive examination (NDE), characterization of proof testing, documentation of quality control or for decisions relative to structural-test termination prior to completion of a planned test. Other NDE methods may be used to provide additional information about located damage regions. For additional information see Appendix X1. 1.3 This practice can be applied to aerospace composite panels and plate-like elements as a part of incoming inspection, during manufacturing, after assembly, continuously (during structural health monitoring) and at periodic intervals during the life of a structure. 1.4 This pra...

  13. Determination of genotoxic potential by comparison of structurally related azo dyes using DNA repair-deficient DT40 mutant panels.

    Science.gov (United States)

    Ooka, Masato; Kobayashi, Koji; Abe, Takuya; Akiyama, Kazuhiko; Hada, Masahiko; Takeda, Shunichi; Hirota, Kouji

    2016-12-01

    Azo dyes, including Sudan I, Orange II and Orange G, are industrial dyes that are assumed to have genotoxic potential. However, neither the type of DNA damage induced nor the structural features responsible for toxicity have been determined. We used a panel of DNA-repair-pathway-deficient mutants generated from chicken DT40 cells to evaluate the ability of these azo dyes to induce DNA damage and to identify the type of DNA damage induced. We compared the structurally related azo dyes Sudan I, Orange II and Orange G to identify the structural features responsible for genotoxicity. Compared with wild type cells, the double-strand break repair defective RAD54-/-/KU70-/- cells were significantly more sensitive to Sudan I, but not to Orange II or Orange G. The quantum-chemical calculations revealed that Sudan I, but not Orange II or Orange G, has a complete planar aromatic ring structure. These suggest that the planar feature of Sudan I is critical to the inducing of double-strand breaks. In summary, we used a DNA-repair mutant panel in combination with quantum-chemical calculations to provide a clue to the chemical structure responsible for genotoxicity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Effects of Various Blowout Panel Configurations on the Structural Response of Los Alamos National Laboratory Building 16-340 to Internal Explosions

    Energy Technology Data Exchange (ETDEWEB)

    Wilke, Jason P. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

    2005-09-01

    The risk of accidental detonation is present whenever any type of high explosives processing activity is performed. These activities are typically carried out indoors to protect processing equipment from the weather and to hide possibly secret processes from view. Often, highly strengthened reinforced concrete buildings are employed to house these activities. These buildings may incorporate several design features, including the use of lightweight frangible blowout panels, to help mitigate blast effects. These panels are used to construct walls that are durable enough to withstand the weather, but are of minimal weight to provide overpressure relief by quickly moving outwards and creating a vent area during an accidental explosion. In this study the behavior of blowout panels under various blast loading conditions was examined. External loadings from explosions occurring in nearby rooms were of primary interest. Several reinforcement systems were designed to help blowout panels resist failure from external blast loads while still allowing them to function as vents when subjected to internal explosions. The reinforcements were studied using two analytical techniques, yield-line analysis and modal analysis, and the hydrocode AUTODYN. A blowout panel reinforcement design was created that could prevent panels from being blown inward by external explosions. This design was found to increase the internal loading of the building by 20%, as compared with nonreinforced panels. Nonreinforced panels were found to increase the structural loads by 80% when compared to an open wall at the panel location.

  15. Failure Predictions of Out-of-Autoclave Sandwich Joints with Delaminations Under Flexure Loads

    Science.gov (United States)

    Nordendale, Nikolas A.; Goyal, Vinay K.; Lundgren, Eric C.; Patel, Dhruv N.; Farrokh, Babak; Jones, Justin; Fischetti, Grace; Segal, Kenneth N.

    2015-01-01

    An analysis and a test program was conducted to investigate the damage tolerance of composite sandwich joints. The joints contained a single circular delamination between the face-sheet and the doubler. The coupons were fabricated through out-of-autoclave (OOA) processes, a technology NASA is investigating for joining large composite sections. The four-point bend flexure test was used to induce compression loading into the side of the joint where the delamination was placed. The compression side was chosen since it tends to be one of the most critical loads in launch vehicles. Autoclave cure was used to manufacture the composite sandwich sections, while the doubler was co-bonded onto the sandwich face-sheet using an OOA process after sandwich panels were cured. A building block approach was adopted to characterize the mechanical properties of the joint material, including the fracture toughness between the doubler and face-sheet. Twelve four-point-bend samples were tested, six in the sandwich core ribbon orientation and six in sandwich core cross-ribbon direction. Analysis predicted failure initiation and propagation at the pre-delaminated location, consistent with experimental observations. A building block approach using fracture analyses methods predicted failure loads in close agreement with tests. This investigation demonstrated a small strength reduction due to a flaw of significant size compared to the width of the sample. Therefore, concerns of bonding an OOA material to an in-autoclave material was mitigated for the geometries, materials, and load configurations considered.

  16. Composition and structure of balsa (Ochroma pyramidale) wood

    OpenAIRE

    Borrega, Marc; Ahvenainen, Patrik; Serimaa, Ritva; Gibson, Lorna

    2014-01-01

    Balsa, with its low density and relatively high mechanical properties, is frequently used as the core in structural sandwich panels, in applications ranging from wind turbine blades to racing yachts. Here, both the cellular and cell wall structure of balsa are described, to enable multi-scale modeling and an improved understanding of its mechanical properties. The cellular structure consists of fibers (66–76 %), rays (20–25 %) and vessels (3–9 %). The density of balsa ranges from roughly 60 t...

  17. Mechanical Characterization of In and Out-of-Autoclave Cured Composite Panels for Large Launch Vehicles

    Science.gov (United States)

    Kellas, Sotiris; Lerch, Bradley A.; Wilmoth, Nathan

    2012-01-01

    Two manufacturing demonstration panels (1/16th-arc-segments of 10 m diameter cylinder) were fabricated under the composites part of the Lightweight Space Structures and Materials program. Both panels were of sandwich construction with aluminum core and 8-ply quasi-isotropic graphite/epoxy facesheets. One of the panels was constructed with in-autoclave curable unidirectional prepreg (IM7/977-3) and the second with out-of-autoclave unidirectional prepreg (T40-800B/5320-1). Following NDE inspection, each panel was divided into a number of small specimens for material property characterization and a large (0.914 m wide by 1.524 m long) panel for a buckling study. Results from the small specimen tests were used to (a) assess the fabrication quality of each 1/16th arc segment panel and (b) to develop and/or verify basic material property inputs to Finite Element analysis models. The mechanical performance of the two material systems is assessed at the coupon level by comparing average measured properties such as flatwise tension, edgewise compression, and facesheet tension. The buckling response of the 0.914 m wide by 1.524 m long panel provided a comparison between the in- and out-of autoclave systems at a larger scale.

  18. Investigation of out of plane compressive strength of 3D printed sandwich composites

    Science.gov (United States)

    Dikshit, V.; Yap, Y. L.; Goh, G. D.; Yang, H.; Lim, J. C.; Qi, X.; Yeong, W. Y.; Wei, J.

    2016-07-01

    In this study, the 3D printing technique was utilized to manufacture the sandwich composites. Composite filament fabrication based 3D printer was used to print the face-sheet, and inkjet 3D printer was used to print the sandwich core structure. This work aims to study the compressive failure of the sandwich structure manufactured by using these two manufacturing techniques. Two different types of core structures were investigated with the same type of face-sheet configuration. The core structures were printed using photopolymer, while the face-sheet was made using nylon/glass. The out-of-plane compressive strength of the 3D printed sandwich composite structure has been examined in accordance with ASTM standards C365/C365-M and presented in this paper.

  19. Titanium-silicon carbide composite lattice structures

    Science.gov (United States)

    Moongkhamklang, Pimsiree

    Sandwich panel structures with stiff, strong face sheets and lightweight cellular cores are widely used for weight sensitive, bending dominated loading applications. The flexural stiffness and strength of a sandwich panel is determined by the stiffness, strength, thickness, and separation of the face sheets, and by the compressive and shear stiffness and strength of the cellular core. Panel performance can be therefore optimized using cores with high specific stiffness and strength. The specific stiffness and strength of all cellular materials depends upon the specific elastic modulus and strength of the material used to make the structure. The stiffest and strongest cores for ambient temperature applications utilize carbon fiber reinforced polymer (CFRP) honeycombs and lattice structures. Few options exist for lightweight sandwich panels intended for high temperature uses. High temperature alloys such as Ti-6A1-4V can be applied to SiC monofilaments to create very high specific modulus and strength fibers. These are interesting candidates for the cores of elevated temperature sandwich structures such as the skins of hypersonic vehicles. This dissertation explores the potential of sandwich panel concepts that utilize millimeter scale titanium matrix composite (TMC) lattice structures. A method has been developed for fabricating millimeter cell size cellular lattice structures with the square or diamond collinear truss topologies from 240 mum diameter Ti-6A1-4V coated SiC monofilaments (TMC monofilaments). Lattices with relative densities in the range 10% to 20% were manufactured and tested in compression and shear. Given the very high compressive strength of the TMC monofilaments, the compressive strengths of both the square and diamond lattices were dominated by elastic buckling of the constituent struts. However, under shear loading, some of the constituent struts of the lattices are subjected to tensile stresses and failure is then set by tensile failure of the

  20. Shear properties evaluation of a truss core of sandwich beams

    Science.gov (United States)

    Wesolowski, M.; Ludewicz, J.; Domski, J.; Zakrzewski, M.

    2017-10-01

    The open-cell cores of sandwich structures are locally bonded to the face layers by means of adhesive resin. The sandwich structures composed of different parent materials such as carbon fibre composites (laminated face layers) and metallic core (aluminium truss core) brings the need to closely analyse their adhesive connections which strength is dominated by the shear stress. The presented work considers sandwich beams subjected to the static tests in the 3-point bending with the purpose of estimation of shear properties of the truss core. The main concern is dedicated to the out-of plane shear modulus and ultimate shear stress of the aluminium truss core. The loading of the beam is provided by a static machine. For the all beams the force - deflection history is extracted by means of non-contact optical deflection measurement using PONTOS system. The mode of failure is identified for each beam with the corresponding applied force. A flexural rigidity of the sandwich beams is also discussed based on force - displacement plots.

  1. ACT Payload Shroud Structural Concept Analysis and Optimization

    Science.gov (United States)

    Zalewski, Bart B.; Bednarcyk, Brett A.

    2010-01-01

    Aerospace structural applications demand a weight efficient design to perform in a cost effective manner. This is particularly true for launch vehicle structures, where weight is the dominant design driver. The design process typically requires many iterations to ensure that a satisfactory minimum weight has been obtained. Although metallic structures can be weight efficient, composite structures can provide additional weight savings due to their lower density and additional design flexibility. This work presents structural analysis and weight optimization of a composite payload shroud for NASA s Ares V heavy lift vehicle. Two concepts, which were previously determined to be efficient for such a structure are evaluated: a hat stiffened/corrugated panel and a fiber reinforced foam sandwich panel. A composite structural optimization code, HyperSizer, is used to optimize the panel geometry, composite material ply orientations, and sandwich core material. HyperSizer enables an efficient evaluation of thousands of potential designs versus multiple strength and stability-based failure criteria across multiple load cases. HyperSizer sizing process uses a global finite element model to obtain element forces, which are statistically processed to arrive at panel-level design-to loads. These loads are then used to analyze each candidate panel design. A near optimum design is selected as the one with the lowest weight that also provides all positive margins of safety. The stiffness of each newly sized panel or beam component is taken into account in the subsequent finite element analysis. Iteration of analysis/optimization is performed to ensure a converged design. Sizing results for the hat stiffened panel concept and the fiber reinforced foam sandwich concept are presented.

  2. Standard Test Method for Sandwich Corrosion Test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 This test method defines the procedure for evaluating the corrosivity of aircraft maintenance chemicals, when present between faying surfaces (sandwich) of aluminum alloys commonly used for aircraft structures. This test method is intended to be used in the qualification and approval of compounds employed in aircraft maintenance operations. 1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information. 1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific hazard statements appear in Section 9.

  3. REINFORCED COMPOSITE PANEL

    DEFF Research Database (Denmark)

    2003-01-01

    A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....

  4. Intermediate-scale Fire Performance of Composite Panels under Varying Loads

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Alexander [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jernigan, Dann A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Dodd, Amanda B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-04-01

    New aircraft are being designed with increasing quantities of composite materials used in their construction. Different from the more traditional metals, composites have a higher propensity to burn. This presents a challenge to transportation safety analyses, as the aircraft structure now represents an additional fuel source involved in the fire scenario. Most of the historical fire testing of composite materials is aime d at studying kinetics, flammability or yield strength under fire conditions. Most of this testing is small - scale. Heterogeneous reactions are often length - scale dependent, and this is thought to be particularly true for composites which exhibit signific ant microscopic dynamics that can affect macro - scale behavior. We have designed a series of tests to evaluate composite materials under various structural loading conditions with a consistent thermal condition. We have measured mass - loss , heat flux, and temperature throughout the experiments. Several types of panels have been tested, including simple composite panels, and sandwich panels. The main objective of the testing was to understand the importance of the structural loading on a composite to its b ehavior in response to fire - like conditions. During flaming combustion at early times, there are some features of the panel decomposition that are unique to the type of loading imposed on the panels. At load levels tested, fiber reaction rates at later t imes appear to be independent of the initial structural loading.

  5. THE INFLUENCE OF ARAB SPRING EFFECT ON ECONOMIC GROWTH IN THE MIDDLE EAST COUNTRIES: STRUCTURAL BREAK PANEL DATA ANALYSIS

    Directory of Open Access Journals (Sweden)

    Murat Beser

    2017-09-01

    Full Text Available Civil commotions that are started in December, 2010 and named as “Arab Spring” had been spread to Middle East countries and had also brought with it economic and political crises. Many economic, social and political factors that are mostly structural had been effective on starting this process. In this research, influence of Arab Spring on economic growth had been investigated with the help of cross-sectional dependency and structural break unit root test in five Middle East countries by using annual data in between 1990-2014. While cross-sectional dependency has been determined for the overall of panel, it had been reached to the conclusion that there is not structural break unit root.

  6. Assessment of foam fracture in sandwich beams using thermoelastic stress analysis

    DEFF Research Database (Denmark)

    Dulieu-Barton, J.M.; Berggreen, Christian; Mettemberg, C.

    2009-01-01

    Thermoelastic Stress Analysis (TSA) has been well established for determining crack-tip parameters in metallic materials. This paper examines its ability to determine accurately the crack-tip parameters for PVC foam used in sandwich structures.......Thermoelastic Stress Analysis (TSA) has been well established for determining crack-tip parameters in metallic materials. This paper examines its ability to determine accurately the crack-tip parameters for PVC foam used in sandwich structures....

  7. Structural behavior of lightweight bamboo reinforced concrete slab with EPS infill panel

    Science.gov (United States)

    Wibowo, Ari; Wijatmiko, Indradi; Nainggolan, Christin Remayanti

    2017-09-01

    Eco-friendly, green, and natural materials have become increasingly important issues in supporting sustainable development, for the substitution of nonrenewable materials such as steel. Bamboo has been considered in many studies to replace steel in reinforced concrete elements. Further investigation has been carried out to obtain lightweight and eco-friendly reinforced concrete slabs by using bamboo bars as reinforcement and recycled materials such as EPS (expanded polystyrene) as infill panel. The flexural loading test on full scale one-way slabs test has been conducted. The results showed that the flexural strength of specimens decreased marginally of about 6% but with the weight advantage of 27% less compared with those of steel rebar reinforced concrete slab with the same dimension. Two type shear-connectors comprising of concrete and bamboo studs were also investigated which showed that the bamboo stud provided better ductility compared to that of slab with concrete as shear connector. Overall, the reinforced concrete slab with bamboo reinforcement and EPS infill panel showed reasonably good performance compared to slabs with steel rebar.

  8. Quasi-Static Compression and Low-Velocity Impact Behavior of Tri-Axial Bio-Composite Structural Panels Using a Spherical Head

    Science.gov (United States)

    Li, Jinghao; Hunt, John F; Gong, Shaoqin; Cai, Zhiyong

    2017-01-01

    This paper presents experimental results of both quasi-static compression and low-velocity impact behavior for tri-axial bio-composite structural panels using a spherical load head. Panels were made having different core and face configurations. The results showed that panels made having either carbon fiber fabric composite faces or a foam-filled core had significantly improved impact and compressive performance over panels without either. Different localized impact responses were observed based on the location of the compression or impact relative to the tri-axial structural core; the core with a smaller structural element had better impact performance. Furthermore, during the early contact phase for both quasi-static compression and low-velocity impact tests, the panels with the same configuration had similar load-displacement responses. The experimental results show basic compression data could be used for the future design and optimization of tri-axial bio-composite structural panels for potential impact applications. PMID:28772542

  9. Quasi-Static Compression and Low-Velocity Impact Behavior of Tri-Axial Bio-Composite Structural Panels Using a Spherical Head

    Directory of Open Access Journals (Sweden)

    Jinghao Li

    2017-02-01

    Full Text Available This paper presents experimental results of both quasi-static compression and low-velocity impact behavior for tri-axial bio-composite structural panels using a spherical load head. Panels were made having different core and face configurations. The results showed that panels made having either carbon fiber fabric composite faces or a foam-filled core had significantly improved impact and compressive performance over panels without either. Different localized impact responses were observed based on the location of the compression or impact relative to the tri-axial structural core; the core with a smaller structural element had better impact performance. Furthermore, during the early contact phase for both quasi-static compression and low-velocity impact tests, the panels with the same configuration had similar load-displacement responses. The experimental results show basic compression data could be used for the future design and optimization of tri-axial bio-composite structural panels for potential impact applications.

  10. Testing panels in shear and biaxial compression

    Science.gov (United States)

    Neary, J. K.

    1979-01-01

    Hydraulic jacks simultaneously apply torsion, axial compression, and lateral compression to structural panels. Jacks are suitable for testing large panels used in aircraft, lightweight trucks, and buses.

  11. Advanced Mechanical Testing of Sandwich Materials

    DEFF Research Database (Denmark)

    Hayman, Brian; Berggreen, Christian; Jenstrup, Claus

    2008-01-01

    An advanced digital optical system has been used to measure surface strains on sandwich face and core specimens tested in a project concerned with improved criteria for designing sandwich X-joints. The face sheet specimens were of glass reinforced polyester and were tested in tension. The core sp...

  12. ENERGY DEMANDS OF THE EXISTING COLLECTIVE BUILDINGS WITH BEARING STRUCTURE OF LARGE PRECAST CONCRETE PANELS FROM TIMISOARA

    Directory of Open Access Journals (Sweden)

    Pescari S.

    2015-05-01

    Full Text Available One of the targets of EU Directives on the energy performance of buildings is to reduce the energy consumption of the existing buildings by finding efficient solutions for thermal rehabilitation. In order to find the adequate solutions, the first step is to establish the current state of the buildings and to determine their actual energy consumption. The current paper aims to present the energy demands of the existing buildings with bearing structure of large precast concrete panels in the city of Timisoara. Timisoara is one of the most important cities in the west side of Romania, being on the third place in terms of size and economic development. The Census of Population and Housing of 2011 states that Timisoara has about 127841 private dwellings and 60 percent of them are collective buildings. Energy demand values of the existing buildings with bearing structure of large precast concrete panels in Timisoara, in their current condition, are higher than the accepted values provided in the Romanian normative, C107. The difference between these two values can reach up to 300 percent.

  13. A Multi-scale Refined Zigzag Theory for Multilayered Composite and Sandwich Plates with Improved Transverse Shear Stresses

    Science.gov (United States)

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

    2013-01-01

    The Refined Zigzag Theory (RZT) enables accurate predictions of the in-plane displacements, strains, and stresses. The transverse shear stresses obtained from constitutive equations are layer-wise constant. Although these transverse shear stresses are generally accurate in the average, layer-wise sense, they are nevertheless discontinuous at layer interfaces, and thus they violate the requisite interlaminar continuity of transverse stresses. Recently, Tessler applied Reissner's mixed variational theorem and RZT kinematic assumptions to derive an accurate and efficient shear-deformation theory for homogeneous, laminated composite, and sandwich beams, called RZT(m), where "m" stands for "mixed". Herein, the RZT(m) for beams is extended to plate analysis, where two alternative assumptions for the transverse shear stresses field are examined: the first follows Tessler's formulation, whereas the second is based on Murakami's polynomial approach. Results for elasto-static simply supported and cantilever plates demonstrate that Tessler's formulation results in a powerful and efficient structural theory that is well-suited for the analysis of multilayered composite and sandwich panels.

  14. Paneling architectural freeform surfaces

    KAUST Repository

    Eigensatz, Michael

    2010-07-26

    The emergence of large-scale freeform shapes in architecture poses big challenges to the fabrication of such structures. A key problem is the approximation of the design surface by a union of patches, socalled panels, that can be manufactured with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication often dominates the panel cost, there is strong incentive to use the same mold for multiple panels. We cast the major practical requirements for architectural surface paneling, including mold reuse, into a global optimization framework that interleaves discrete and continuous optimization steps to minimize production cost while meeting user-specified quality constraints. The search space for optimization is mainly generated through controlled deviation from the design surface and tolerances on positional and normal continuity between neighboring panels. A novel 6-dimensional metric space allows us to quickly compute approximate inter-panel distances, which dramatically improves the performance of the optimization and enables the handling of complex arrangements with thousands of panels. The practical relevance of our system is demonstrated by paneling solutions for real, cutting-edge architectural freeform design projects. © 2010 ACM.

  15. Paneling architectural freeform surfaces

    KAUST Repository

    Eigensatz, Michael

    2010-07-25

    The emergence of large-scale freeform shapes in architecture poses big challenges to the fabrication of such structures. A key problem is the approximation of the design surface by a union of patches, so-called panels, that can be manufactured with a selected technology at reasonable cost, while meeting the design intent and achieving the desired aesthetic quality of panel layout and surface smoothness. The production of curved panels is mostly based on molds. Since the cost of mold fabrication often dominates the panel cost, there is strong incentive to use the same mold for multiple panels. We cast the major practical requirements for architectural surface paneling, including mold reuse, into a global optimization framework that interleaves discrete and continuous optimization steps to minimize production cost while meeting user-specified quality constraints. The search space for optimization is mainly generated through controlled deviation from the design surface and tolerances on positional and normal continuity between neighboring panels. A novel 6-dimensional metric space allows us to quickly compute approximate inter-panel distances, which dramatically improves the performance of the optimization and enables the handling of complex arrangements with thousands of panels. The practical relevance of our system is demonstrated by paneling solutions for real, cutting-edge architectural freeform design projects.

  16. Solar reflection panels

    Science.gov (United States)

    Diver, Jr., Richard B.; Grossman, James W [Albuquerque, NM; Reshetnik, Michael [Boulder, CO

    2006-07-18

    A solar collector comprising a glass mirror, and a composite panel, wherein the back of the mirror is affixed to a front surface of the composite panel. The composite panel comprises a front sheet affixed to a surface of a core material, preferably a core material comprising a honeycomb structure, and a back sheet affixed to an opposite surface of the core material. The invention may further comprise a sealing strip, preferably comprising EPDM, positioned between the glass mirror and the front surface of the composite panel. The invention also is of methods of making such solar collectors.

  17. FEATURES OF WELDED TITANIUM STRUCTURE ELEMENT DESTRUCTION (RIBBED PANELS UNDER VIBRATION LOADS

    Directory of Open Access Journals (Sweden)

    Mr. Pavel V. Bakhmatov

    2016-12-01

    Full Text Available The article presents data on the experimental studies results of welded ribbed panel vibration load of the BT-20 titanium alloy. It was established that in the areas of attachment, there is elevated dynamic alternating stress, which in combination with the "hard" of the sample holder creates favorable conditions for the emergence and development of fatigue cracks, and stress concentrators greatly reduce the time before the formation of the hearth destruction. An exception in these zones of superficial defects do not affect the nature and kinetics of destruction. Construction of titanium alloys made in the application of gas-laser cutting blanks for optimal regimes in the technical environment of nitrogen and subsequent heat treatment on vibration reliability is not inferior to design, made by traditional technology.

  18. NASA Office of Aeronautical and Space Technology Summer Workshop. Volume 6: Structures and dynamics panel

    Science.gov (United States)

    1975-01-01

    Structural requirements for future space missions were defined in relation to technology needs and payloads. Specific areas examined include: large area space structures (antennas, solar array structures, and platforms); a long, slender structure or boom used to support large objects from the shuttle or hold two bodies apart in space; and advanced composite structures for cost effective weight reductions. Other topics discussed include: minimum gage concepts, high temperature components, load and response determination and control, and reliability and life prediction.

  19. Synthesis, molecular and electronic structure of a stacked half-sandwich dititanium complex incorporating a cyclic p-faced bridging ligand

    Czech Academy of Sciences Publication Activity Database

    Gyepes, R.; Pinkas, Jiří; Císařová, I.; Kubišta, Jiří; Horáček, Michal; Mach, Karel

    2016-01-01

    Roč. 6, č. 96 (2016), s. 94149-94159 ISSN 2046-2069 R&D Projects: GA ČR(CZ) GAP207/12/2368 Institutional support: RVO:61388955 Keywords : atoms * carbon * electronic structure Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.108, year: 2016

  20. Mounting clips for panel installation

    Energy Technology Data Exchange (ETDEWEB)

    Cavieres, Andres; Al-Haddad, Tristan; Goodman, Joseph

    2017-07-11

    A photovoltaic panel mounting clip comprising a base, central indexing tabs, flanges, lateral indexing tabs, and vertical indexing tabs. The mounting clip removably attaches one or more panels to a beam or the like structure, both mechanically and electrically. It provides secure locking of the panels in all directions, while providing guidance in all directions for accurate installation of the panels to the beam or the like structure.