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‣ Spectrophotometric Determination of Aluminium in Iron Ores Using Solid-Phase Extraction

Ferreira,Sérgio Luis Costa; Lemos,Valfredo Azevedo; Costa,Antônio Celso Spinola; Jesus,Djane Santiago de; Carvalho,Marcelo Souza de
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/1998 Português
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433.6897%
In the present paper, a procedure for separation and determination of aluminium in iron matrices is proposed. It is based on the solid-phase extraction of the iron, in the form of thiocyanate complexes, by a polyurethane(PU) foam. The followings parameters were studied: effect of pH and of the thiocyanate concentration on the iron extraction, shaking time required for quantitative extraction, amount of PU foam necessary for complete extraction of iron, aluminium separation from other cations, influence of anions on the iron sorption by PU foam and analytical characteristics of the procedure for aluminium determination using methylthymol blue as chromogenic reagent. The results show that, in the pH range from 1.5 to 4.7, with a thiocyanate concentration of 0.80 mol L-1, by extraction using 1 g of polyurethane foam and a shaking time of 1 min, aluminium (40 mug) can be separated from large amounts of iron (10 mg), 800 mug of copper(II), cobalt(II), zinc(II), mercury(II), tin(IV), manganese(II) and tungsten(V); 100 mug of titanium(IV) and lead(II); and 50 mug of vanadium(V). Calcium(II), barium(II), strontium(II) and magnesium(II) can not be separated by this process, but do not react with MTB under the conditions used for aluminium determination. The anions nitrate...

‣ Process Development for Manufacturing of Cellular Structures with Controlled Geometry and Properties

Pinto,Paulo; Peixinho,Nuno; Soares,Delfim; Silva,Filipe
Fonte: ABM, ABC, ABPol Publicador: ABM, ABC, ABPol
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2015 Português
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398.91477%
This study presents experimental results on the behaviour of aluminium alloy metal structures and foams manufactured by lost-wax casting and using 3D printed components for internal structure definition. Results for tensile tests, metallurgical properties, surface quality and geometry tolerances were obtained and discussed. The analysis focused on development geometries, used for adjusting manufacturing parameters and prototype geometries intended for geometrical and mechanical validation. The results are indicative of the viability of the method for producing foam structures suitable for mechanical loading.

‣ Characterisation of the flexural behaviour of Aluminium Foam Sandwich Structures

Styles, Millicent
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Thesis (PhD); Doctor of Philosophy (PhD)
Português
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721.74125%
Aluminium foam has a range of properties that are desirable in many applications. These properties include good stiffness and strength to weight ratios, impact energy absorption, sound damping, thermal insulation and non combustibility. Many of these characteristics are particularly attractive for core materials within sandwich structures. The combination of aluminium foam cores with thermoplastic composite skins is easily manufactured and has good potential as a multifunctional sandwich structure useful in a range of applications. This thesis has investigated the flexural behaviour of such structures using a combination of experimental and modelling techniques. The development of these structures towards commercial use requires a thorough understanding of the deformation and strain mechanisms of the structure, and this will, in turn, allow predictions of their structural behaviour in a variety of loading conditions. ¶ ...; yes

‣ Mitigation of blast effects on aluminum foam protected masonry walls

Su, Y.; Wu, C.; Griffith, M.
Fonte: Tianjin Daxue Publicador: Tianjin Daxue
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
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506.32465%
Terrorist attacks using improvised explosive devices (IED) can result in unreinforced masonry (URM) wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the performance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the performance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elastoplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads.; Yu Su, Chengqing Wu and Mike Griffith

‣ Experimental investigation of the dynamic behaviour of aluminium foams

Xu, S.; Ruan, D.; Beynon, J.; Lu, G.
Fonte: Trans Tech Publications Ltd Publicador: Trans Tech Publications Ltd
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
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The compressive behavior of two closed cell aluminum foams (Alporas and Cymat) were investigated under various strain rates from 10-3 to 102 s-1 using compressive tests conducted on MTS and Instron test machines. High speed camera videos show that localized deformation occurs in Alporas foam specimens uniformly, but not in Cymat foams. The stress-strain curves for Alporas foams are smooth and regular, while they oscillate dramatically for Cymat foams. Alporas foams exhibit strain rate sensitivity, i.e. with an increase in strain rate, the normalized plateau stress and energy absorption capacity increase. The plateau stress for Cymat foams was more sensitive than Alporas to strain rate, but the energy absorption less so, at least at a nominal relative density of 10%.; Shan Qing Xu, Dong Ruan, John H. Beynon, Guo Xing Lu

‣ Research development on protection of structures against blast loading at University of Adelaide

Wu, C.
Fonte: Institution of Engineers Australia Publicador: Institution of Engineers Australia
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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285.31059%
This paper presents a review of research into the protection of structural members against blast loading at The University of Adelaide, including experimental, analytical and numerical studies on characteristics of blast loading, blast resistance of structural members and mitigation of blasts effects on structural members using retrofitting techniques. Explosive blasts are investigated experimentally and numerically to study the distributions of peak overpressure and impulse generated from spherical charges and cylindrical charges with different orientations in unconfined and confined environments. A series of blast tests on reinforced concrete (RC) slabs, ultra-high performance concrete (UHPC) slabs, and aluminium foam protected RC slabs was conducted to investigate the performance of those slabs under blast loads. With the blast testing data numerical models including single degree of freedom model, finite difference model and final element model, have been developed and validated and those numerical models are then used to analyse the blast effects of RC, UHPC and foam protected RC slabs. Investigation of mitigation of blast effects on masonry structures is also addressed.; C Wu

‣ Simulation of retrofitted unreinforced concrete masonry unit walls under blast loading

Aghdamy, S.; Wu, C.; Griffith, M.
Fonte: Multi-Science Publishing Co Ltd Publicador: Multi-Science Publishing Co Ltd
Tipo: Artigo de Revista Científica
Publicado em //2013 Português
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This paper describes an investigation into the effectiveness of using spray-on nano-particle reinforced polymer and aluminium foam as new types of retrofit material to prevent the breaching and collapse of unreinforced concrete masonry walls subjected to blast over a whole range of dynamic and impulsive regimes. Material models from the LS-DYNA material library were used to model the behaviors of each of the materials and its interface for retrofitted and unretrofitted masonry walls. Available test data were used to validate the numerical models. Using the validated LS-DYNA numerical models, the pressure-impulse diagrams for retrofitted concrete masonry walls were constructed. The efficiency of using these retrofits to strengthen the unreinforced concrete masonry unit (CMU) walls under various pressures and impulses was investigated using pressure-impulse diagrams. Comparisons were made to find the most efficient retrofits for masonry walls against blasts.; Sanam Aghdamy, Chengqing Wu and Michael Griffith

‣ Measurement of longitudinal and transverse strain in an aluminium foam

GOGLIO Luca; MANFREDINI VASSOLER Jakson; PERONI MARCO
Fonte: WILEY-V C H VERLAG GMBH Publicador: WILEY-V C H VERLAG GMBH
Tipo: Articles in Journals Formato: Printed
Português
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513.15008%
This paper presents an experimental study on a closed-cell aluminium foam (ALPORAS®), carried out with the final goal of obtaining data required to identify the parameters of a constitutive model of such material. The work consists mainly of compression tests on prismatic specimens, from which the load-displacement curves are obtained. Several tests have been carried out to assess the influence of strain rate, in the low-value range 10-3¿10-1 s-1, and foam density variation, due to the slight difference between samples taken from the inner or the outside of a foam block. The results show that the effect of the strain rate, although small, is noticeable, and becomes more relevant when the material has higher density, in accordance with previous studies. Measuring the strain in the foam requires special procedures because of its heterogeneity; the typical choice is in favour of non-contact methods. In this work, the Digital Image Correlation has been used to obtain the displacement field on the specimen surface: the track of each marker point in a chosen set has been determined, then the strain field has been assessed with an interpolation based on a strain-displacement matrix like in the finite element method. The obtained relationship between longitudinal and transverse average strain is non-linear and influenced by the strain rate...

‣ Impact behaviour testing of aluminium foam

PERONI MARCO; SOLOMOS George; PIZZINATO Erminio
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Articles in Journals Formato: Printed
Português
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517.43062%
There is strong interest in employing lightweight metallic foams for automotive and aerospace applications, where weight reduction, and mechanical energy absorption and acoustic damping capacity are required. Knowledge of the mechanical behavior of these materials, especially under dynamic loadings, is thus necessary. This work presents an extensive study of strain-rate sensitivity of a specific aluminium foam using a Split Hopkinson Pressure Bar technique adapted to perform tests on low strength / low impedance materials. All dynamic tests have been performed using a SHPB which adopts a long, pre-stressed steel bar to generate the compressive wave and aluminium tubular bars to load the foam specimen. The advantages of this configuration are that the loading pulse reaches a duration of almost 4 ms and that it allows tests to be carried out on specimens with a sufficiently large representative volume (usually SHPB tests on metallic foams have been performed on less representative specimens due to lower specimen / cell volume ratio). The stress-strain curves of all specimens at different strain-rates have been obtained by adopting the classical SHPB theory and some analytical procedures to compensate for dispersion phenomena. Experimental tests have been performed on aluminium foams with two different densities (approximately 150 kg/m3 and 300 kg/m3) using specimens of diameter 50 mm and a length varying between 15 mm and 50 mm. The influence of loading direction (x...

‣ Impact behaviour of aluminium foam

PERONI MARCO; SOLOMOS George; PIZZINATO Erminio; LANGSETH M.; HOPPERSTAD O.s.
Fonte: University of Valenciennes - LAMIH Publicador: University of Valenciennes - LAMIH
Tipo: Contributions to Conferences Formato: CD-ROM
Português
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This paper presents a dynamic experimental study of mechanical behaviour of an aluminium foam subjected to crash/impact loadings using SHPB techniques; JRC.G.5-European laboratory for structural assessment

‣ Investigación de propiedades de mecanizado de espuma de aluminio; Research of properties of aluminium foam machining

Bernal del Castillo, Álvaro
Fonte: Universidade de Cantabria Publicador: Universidade de Cantabria
Tipo: Trabalho de Conclusão de Curso
Português
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385.3106%
This document describes machining of metal foams. It is known that this materials are extremely porous, so with this experiment it will be tried to find the best way of machining to have the less possible porosity in the machined surface, also it pretends to reduce the roughness of this surface. Given the very broad group of metal foams, we are in the research focused on aluminum foam with a closed - cell structure. Treatment of samples was held at the Faculty of Mechanical Engineering in Maribor, on the CNC lathe Doosan Lynx 220LM. Other technological parameters such as rotational speed, feed rate and depth of cut, the final porosity of the treated surfaces do not have such an effect.; Grado en Ingeniería Mecánica

‣ The use of dolomite as foaming agent and its effect on the microstructure of aluminium metal foams—Comparison to titanium hydride

Papadopoulos, D. P.; Omar, H.; Stergioudi, F.; Tsipas, Sophia Alexandra; Michailidis, N.
Fonte: Elsevier Publicador: Elsevier
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article; info:eu-repo/semantics/conferenceObject
Publicado em /06/2011 Português
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385.5422%
In this paper dolomite MgCa(CO₃)₂ a naturally occurring mineral was demonstrated to be an effective foaming and stabilizing agent for aluminium with several notable advantages relative to the currently used titanium hydride foaming agent. Characteristic cell structures and microstructural features of foams produced with a dolomite foaming agent are examined and the properties of dolomite based foams produced in a one step process are compared with those produced using titanium hydride based process. The most notable structural feature of dolomite based foams is a smaller cell size and thinner cell faces. Foaming with MgCa(CO₃)₂ also gives rise to a marked increase in the stability of molten foams with a large range of foaming temperatures possible, and an almost complete absence of melt drainage even with extended foaming times. Many of these properties are attributed to the cell surfaces being covered by a thin oxide film formed during the foaming process.; Proceedings of: 8th EUFOAM Conference. Borovets, Bulgaria, 14-16 July 2010.

‣ Structure and deformation correlation of closed-cell aluminium foam subject to uniaxial compression

Saadatfar, M.; Mukherjee, M.; Madadi, M.; Schröder-Turk, G.E.; Garcia-Moreno, F.; Schaller, F.M.; Hutzler, S.; Sheppard, A.P.; Banhart, J.; Ramamurty, U.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica Formato: 12 pages
Português
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516.8536%
We report the results of an experimental and numerical study conducted on a closed-cell aluminium foam that was subjected to uniaxial compression with lateral constraint. X-ray computed tomography was utilized to gain access into the three-dimensional (3-D) structure of the foam and some aspects of the deformation mechanisms. A series of advanced 3-D image analyses are conducted on the 3-D images aimed at characterizing the strain localization regions. We identify the morphological/geometrical features that are responsible for the collapse of the cells and the strain localization. A novel mathematical approach based on a Minkowski tensor analysis along with the mean intercept length technique were utilized to search for signatures of anisotropy across the foam sample and its evolution as a function of loading. Our results show that regions with higher degrees of anisotropy in the undeformed foam have a tendency to initiate the onset of cell collapse. Furthermore, we show that strain hardening occurs predominantly in regions with large cells and high anisotropy. We combine the finite element method with the tomographic images to simulate the mechanical response of the foam. We predict further deformation in regions where the foam is already deformed.

‣ Characterization of Thermo-Fluid Transport Properties of Coated and Uncoated Open-Cell Metal Foam Monoliths

THOMAS, EDWARD ANTHONY
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
Português
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505.91945%
An improved steady-state method combining experiment and mathematical modelling has been developed to characterize the scalable convective heat transfer coefficient, hvol [W*m^(-3)*K^(-1)], of uncoated and catalyst-support coated aluminium foam monoliths. The values of hvol were recovered by parameter fitting its model values to experimental temperature data for steady-state air-cooled monoliths under a known heating flux. The model was built with experimentally recovered values of the monolith’s thermal conductivity and fluid permeability along with known values for other physical parameters. The volumetric heat transfer coefficients of 10, 20 and 40 pore-per-inch uncoated aluminium foams were determined to range between 2,700 and 20,000 W*m^(-3)*K^(-1) at channel Reynolds numbers between 85 and 1,700. The presence of a 76 micron thick anodized layer of catalyst support on monolith foams effected a small but significant reduction in the value of hvol. Coating with an anodized layer also reduced the permeabilities of the monoliths to air flow by 4-20%. Knowledge of the scalable parameter, hvol, was used to model a steady-state non-isothermal, non-isobaric heat-coupled methanol reformer. The model shows that changes to the convective transfer coefficient due to coating the monolith with catalyst support may have significant consequences for the thermal profile of the model reactor and for the product yield.; Thesis (Master...

‣ Finite element modelling of core thickness effects in aluminium foam/composite sandwich structures under flexural loading

Styles, Millicent; Compston, Paul; Kalyanasundaram, Shankar
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
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713.0455%
This paper models the flexural behaviour of a composite sandwich structure with an aluminium foam core using the finite element (FE) code LS-DYNA. Two core thicknesses, 5 and 20 mm, were investigated. The FE results were compared with results from previou

‣ The effect of core thickness on the flexural behaviour of aluminium foam sandwich structures

Styles, Millicent; Compston, Paul; Kalyanasundaram, Shankar
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
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724.66125%
The effect of core thickness on the deformation mechanism of an aluminium foam core/thermoplastic composite facing sandwich structure under 4-point bending was investigated. Full field strain analysis and visual observations show a number of failure mecha

‣ Crushing modes of aluminium tubes under axial compression

Pled, Florent Henri Marc Rémy; Yan, Wenyi; Wen, Cui'E
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 21/08/2014 Português
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413.04543%
A numerical study of the crushing of circular aluminium tubes with and without aluminium foam fillers has been carried out to investigate their buckling behaviours under axial compression. A crushing mode classification chart has been established for empty tubes. The influence of boundary conditions on crushing mode has also been investigated. The effect of foam filler on the crushing mode of tubes filled with foam was then examined. The predicted results would assist the design of crashworthy tube components with the preferred crushing mode with the maximum energy absorption.; Comment: 6 pages,5th Australasian Congress on Applied Mechanics (ACAM 2007), Brisbane : Australia (2007)

‣ Aluminium foam production using calcium carbonate as a foaming agent

Curran, David C.
Fonte: University of Cambridge; Department of Materials Science and Metallurgy Publicador: University of Cambridge; Department of Materials Science and Metallurgy
Tipo: Thesis; doctoral; PhD
Português
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406.04074%
The current state of the art with regards to the production of metallic foams is reviewed, with melt-based processes identified as the most promising for cost-effective large-scale production. The potential for metal carbonates as an alternative to currently-used titanium hydride foaming agents is explored, with calcium carbonate identified as the most suitable. The influence of a range of material and processing parameters on the stability of metallic foams in the molten state is discussed, and current methods of controlling melt viscosity and surface tension are reviewed. Characteristic features of the compressive deformation of metallic foams are described in the context of use as an impact-absorbing material, with a review of work in the literature linking the bulk mechanical properties to details of the cell structure. Calcium carbonate is found to be a highly effective foaming agent for aluminium. The foams obtained have notably finer cell structures than can be achieved in foams produced with titanium hydride, coupled with enhanced stability in the molten state. This is attributed to the presence of a thin continuous surface film of metallic oxide that counteracts the effect of surface tension. This film, combined with the finer cell structure of the calcium carbonate-based foams...

‣ High velocity impact modelling of sandwich panels with aluminium foam core and aluminium sheet skins

Liu, Chengjun; Zhang , Y X; Qin, Qing Hua; Heslehurst, Rikard Benton
Fonte: Trans Tech Publications Publicador: Trans Tech Publications
Tipo: Conference paper
Português
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527.63195%
A finite element model is developed in this paper to simulate the perforation of aluminium foam sandwich panels subjected to high velocity impact using the commercial finite element analysis software LS-DYNA. The aluminum foam core is governed by the material model of crushable foam materials, while both aluminium alloy face sheets are modeled with the simplified Johnson-Cook material model. A non-linear cohesive contact model is employed to simulate failure between adjacent layers, and an erosion contact model is used to define contact between bullets and panels. All components in the model are meshed with 3D solid element SOLID 164. The developed finite element model is used to simulate the dynamic response of an aluminium foam sandwich panel subjected to projectile impact at velocity ranging from 76 m/s to 187m/s. The relationship between initial velocity and exit velocity of the projectile obtained from numerical modelling agrees well with that obtained from experimental study, demonstrating the effectiveness of the developed finite element model in simulating perforation of sandwich panels subjected to high velocity impact.

‣ Application of sugar foam to vineyard acid soils under Mediterranean conditions

Olego,M.A.; Coque,J.J.R.; Garzón Jimeno,E.
Fonte: South African Journal of Enology and Viticulture Publicador: South African Journal of Enology and Viticulture
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2014 Português
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292.31527%
Calcium (Ca) deficiency and aluminium (Al) toxicity are considered major chemical constraints that limit vine growth in vineyard acid soils under Mediterranean conditions. The main aim of this work was to evaluate the effects of three doses of sugar foam (900, 1 800 and 2 700 kg CaCO3/ha) on five soil properties (pH in water, Ca, Mg, K and Al exchangeable contents) and Ca concentrations in petioles and canes of one wine grape variety. Research was conducted over three seasons (2006 to 2008) in a random block design at León (Spain). The results for plants and soils were subjected to general lineal model analysis. As a result, one linear model, validated through a cross-validation procedure, has been proposed to predict exchangeable calcium levels in vineyard acid soils at véraison. Based on the results for the soils, the higher doses of sugar foam (1 800 and 2 700 kg CaCO3/ha) were the most effective doses in decreasing Al exchangeable and increasing Ca exchangeable contents. In addition, liming increased Ca content in petioles and decreased Ca content in canes, but in both cases these differences were not significant.