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Article
Publication date: 5 March 2018

Ling Weng, Ting Wang, Pei-Hai Ju and Li-Zhu Liu

This paper aims to develope the electromagnetic interference shielding materials with high performance. To develop advanced polymer-based electromagnetic interference…

Abstract

Purpose

This paper aims to develope the electromagnetic interference shielding materials with high performance. To develop advanced polymer-based electromagnetic interference shielding materials with rather high temperature stability, good processability and moderate mechanical properties, the authors chose the polyimide (PI) foam as matrix and ferriferrous oxide (Fe3O4) as fillers to prepare the composite foams with lightweight and rather good electromagnetic interference shielding performance.

Design/methodology/approach

Some polyimide nanocomposite foams with Fe3O4 as fillers have been prepared by in situ dispersion and foaming with pyromellitic dianhydride (PMDA) and isocyanate (PAPI) as raw materials and water as foaming agent. By varying the Fe3O4 contents, a series of PI/Fe3O4 nanocomposite foams with fine microstructures and high thermal stability were obtained. The structure and performances of nanocomposite foams were examined, and the effects of Fe3O4 on the microstructure and properties of composite foams were investigated.

Findings

This work demonstrates that PI/Fe3O4 foams could be fabricated by thermally treating the polyimide foam intermediates with Fe3O4 nanoparticles through a blending reaction of precursors. The final PI/Fe3O4 composite foams maintained the excellent thermal property and showed a super paramagnetic behaviour, which has a positive effect on the improvement of electromagnetic shielding performance.

Research limitations/implications

In this paper, the effects of Fe3O4 on the performances of PI/Fe3O4 composite foam were reported. It provided an effective methodology for the preparation of polymer/Fe3O4 nanocomposite foams, which hold great promise towards the potential application in the areas of electromagnetic shielding materials.

Originality/value

A series of PI/Fe3O4 composite foams with different contents of Fe3O4 were prepared by blending reaction of the precursors. The effects of Fe3O4 on the structures and properties of PI/Fe3O4 composite foam were discussed in detail.

Details

Pigment & Resin Technology, vol. 47 no. 2
Type: Research Article
ISSN: 0369-9420

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Article
Publication date: 1 March 2008

V. Rizov and A. Mladensky

This article presents an approach for assessing the damage resistance of H30 rigid foam subjected to local static loading. The main goal of the experimental part of this…

Abstract

This article presents an approach for assessing the damage resistance of H30 rigid foam subjected to local static loading. The main goal of the experimental part of this paper is to obtain the loaddisplacement response of foam beam specimens under static indentation by steel cylindrical indentors for both loading (indentation) and unloading stages. The instant residual dent magnitude is also measured in the testing. The nonlinear character of the mechanical behavior and the formation of a residual dent (after unloading) are attributed to local crushing of the foam in the zone directly under the indentation area. A visual inspection of a lateral surface of the foam specimens after indentation tests revealed that the local damage underneath the indentor consists of crushed and highly compacted foam, while the rest of the specimen is almost undeformed. A two‐dimensional numerical model is developed to simulate the static indentation response using the ABAQUS computer code. No overall bending of the foam specimens is assumed. The finite element modeling procedure takes into account both physical and geometrical non‐linearities. In order to simulate the plastic part of the response, the model employs the *CRUSHABLE FOAM and *CRUSHABLE FOAM HARDENING options. The modeling procedure is capable of analyzing indentation as well as unloading of foam beam specimens. Thus, the instant residual dent can be predicted. Results generated by this model exhibit good correlation with indentation tests data, thus substantiating its validity.

Details

Multidiscipline Modeling in Materials and Structures, vol. 4 no. 3
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 6 April 2021

Sonika Sahu, Piyush D. Ukey, Narendra Kumar, Ravi Pratap Singh and Mohd. Zahid Ansari

This study aims to generate different three-dimensional (3D) foam models using computer tomography (CT) scan and solid continuum techniques. The generated foam models were…

Abstract

Purpose

This study aims to generate different three-dimensional (3D) foam models using computer tomography (CT) scan and solid continuum techniques. The generated foam models were used to study deformation mechanism and the elastic-plastic behaviour with the existing experimental foam behaviour.

Design/methodology/approach

CT scan model was generated by combing 2D images of foam in MIMICS software. Afterwards, it was imported in ABAQUS/CAE software. However, solid continuum model was generated in ABAQUS/CAE software by using crushable foam properties. Then, the generated foam models were sets boundary conditions for a compression test.

Findings

CT scans capture the actual morphology of foam sample which may directly an image based finite element foam model. The sectional views of both the models were used to observe deformation mechanism on compression. The real compressive behaviour of foam was visualised in CT-Scan foam model. It was observed that CT-scan model was the more accurate modelling method than crushable foam model.

Originality/value

The internal structure of foam is very complex and difficult to analyse. Therefore, CT-scanning may be the accurate method for capturing the macro-level detailing of foam structure. A CT-scan foam model can be used for multiple times for mechanical analysis using a simulation software, which may reduce the manufacturing and the experimental cost and time.

Details

World Journal of Engineering, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1708-5284

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Book part
Publication date: 5 August 2015

Tony Kazda and Bob Caves

Abstract

Details

Airport Design and Operation
Type: Book
ISBN: 978-1-78441-869-4

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Article
Publication date: 2 July 2020

Toqa AL-Kasasbeh and Rabab Allouzi

This research is part of a project that aims to investigate using foamed concrete structurally in houses. Foamed concrete has a porous structure that makes it light in…

Abstract

Purpose

This research is part of a project that aims to investigate using foamed concrete structurally in houses. Foamed concrete has a porous structure that makes it light in weight, good in thermal insulation, good in sound insulation and workable.

Design/methodology/approach

An experimental program is conducted in this research to investigate the behavior of polypropylene fiber reinforced foam concrete beams laterally reinforced with/without glass fiber grid.

Findings

The results proved the effectiveness and efficiency of using glass fiber grid as lateral reinforcements on the shear strength of reinforced foam concrete ribs, in reducing the cracks width and increasing its shear capacity, contrary to using glass fiber grid of reinforced foam concrete beams since glass fiber grid did not play good role in beams.

Originality/value

Limited literature is available regarding the structural use of foam concrete. However, work has been done in many countries concerning its use as insulation material, while limited work was done on structural type of foam concrete.

Details

International Journal of Structural Integrity, vol. 12 no. 3
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 28 November 2019

Makram Elfarhani, Ali Mkaddem, Ahmed A. Alzahrani, Abdullah S. Bin Mahfouz, Abdessalem Jarraya and Mohamed Haddar

The efficiency of fractional derivative and hereditary combined approach in modeling viscoelastic behavior of soft foams was successfully addressed in Elfarhani et al.

Abstract

Purpose

The efficiency of fractional derivative and hereditary combined approach in modeling viscoelastic behavior of soft foams was successfully addressed in Elfarhani et al. (2016a). Since predictions obtained on flexible polyurethane foam (FPF) type A (density 28 kg m−3) were found very promoting, the purpose of this paper is to apply the approach basing on two other types of foams. Both soft polyurethane foams type B of density 42 kg m−3 and type C of density 50 kg m−3 were subjected to multi-cycles compressive tests.

Design/methodology/approach

The total foam response is assumed to be the sum of a non-linear elastic component and viscoelastic component. The elastic force is modeled by a seven-order polynomial function of displacement. The hereditary approach was applied during the loading half-cycles to simulate the short memory effects while the fractional derivative approach was applied during unloading cycles to simulate the long memory effects. An identification methodology based on the separation of the measurements of each component force was developed to avoid parameter admixture problems.

Findings

The proposed model reveals good reliability in predicting the responses of the two considered flexible foams. Predictions as measurements establish that residual responses were negligible compared to elastic and viscoelastic damping responses.

Originality/value

The development of a new combined model reveals good reliability in predicting the responses of the two polyurethane foams type A and B.

Details

Multidiscipline Modeling in Materials and Structures, vol. 16 no. 3
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 7 October 2013

Alessio Carofalo, Marta De Giorgi and Anna Morabito

The aim of this work is the development of a procedure able to model the highly irregular cellular structure of metallic foams on the basis of information obtained by…

Abstract

Purpose

The aim of this work is the development of a procedure able to model the highly irregular cellular structure of metallic foams on the basis of information obtained by X-ray tomographic analysis.

Design/methodology/approach

The geometric modelling is based on the feature “pore” characterized by an ellipsoidal shape. The data for the geometric parameters of the instances are obtained with a methodology which is driven by the pore volume distribution curve. This curve shows how much the cells, whose diameter belongs to a given dimensional range, contribute to the reduction of the total volume.

Findings

The presented methodology has been implemented into a CAD tool consisting of a Matlab routine identifying the instances of the feature “pore” and a CATIA's macro modelling the closed cells foam.

Originality/value

The presented methodology allows to obtain in an automatic way the CAD model of the complex structure of closed cell aluminium foam approximating by considerable accuracy both the density and the volume distribution of the real foams.

Details

Engineering Computations, vol. 30 no. 7
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 28 June 2019

Amin Samimi Behbahan, Aminreza Noghrehabadi, C.P. Wong, Ioan Pop and Morteza Behbahani-Nejad

The purpose of this paper is to study thermal performance of metal foam/phase change materials composite under the influence of the enclosure aspect ratios (ratio of…

Abstract

Purpose

The purpose of this paper is to study thermal performance of metal foam/phase change materials composite under the influence of the enclosure aspect ratios (ratio of enclosure height: length). In this study, a compound metal foam/phase change material (PCM), which has been proved to be one of the most promising approaches for thermal conductivity promotion on PCMs, was used.

Design/methodology/approach

The PCM is considered initially at its melting temperature. The enclosure for all the cases has a constant volume with various aspect ratios. The left side of the enclosure is suddenly exposed to a thermal source having a constant heat flux, while the other three surfaces are kept thermally insulated. A two-dimensional numerical model considering the non-equilibrium thermal factor, non-Darcy effect and local natural convection was proposed. The coupling between velocity and pressure is solved using the SIMPLEC, and the Rhie and Chow interpolation is used to avoid the checker-board solutions for the pressure.

Findings

The effects of foam porosity and aspect ratio of the enclosure on the PCM’s melting time were investigated. The results indicated that enclosure aspect ratio plays a fundamental role in phase change of copper foam/PCM composites. For higher porosities, enclosures with bigger aspect ratios proved to led to optimal melting time. Besides, the best enclosure aspect ratio and foam porosity for a fixed-volume enclosure to have the shortest melting time are 2.1 and 91.66 per cent, respectively. However, for a specific amount of PCM inside a variable volume enclosure, the optimal melting time was for foam with ε = 95 per cent. The achieved results prove the great importance of selection of aspect ratio to benefit both conduction and convection heat transfer simultaneously.

Originality/value

The area of energy storage systems is original.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 9
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 13 June 2016

Q.C. Yang, M.J. Zhang and P. S. Liu

The samples of nickel foam with porosity of about 88 percent were uniaxially tensioned at room temperature, and the phenomena of tensile fracture were compared with that…

Abstract

Purpose

The samples of nickel foam with porosity of about 88 percent were uniaxially tensioned at room temperature, and the phenomena of tensile fracture were compared with that from the fully dense plate of metal nickel. The purpose of this paper is to investigate the differences between their behaviors of tensile fracture.

Design/methodology/approach

The tensile test was carried out by using the tester of CMT-series microcomputer-controlled electronic universal testing machine. The difference of tensile fracture behavior between the nickel foam and the dense metal nickel was discussed by analyzing the load-displacement curve and the microscopical fracture.

Findings

The results indicated that, nickel foam also displayed the feature of macroscopic plastic-deformation during tension, but it showed a macroscopic brittleness much more than that of the fully dense body. The axial apparent strain at the maximum load for the foamed sample was markedly less than that for the dense one. In addition, an obviously gradual course exhibited for the foamed body during tensile failure and a rapidly instant course for the dense body correspondingly.

Originality/value

There have been some studies on the tensile behavior for metal foams, but much less than on the compression, and the relevant works are mostly for aluminum foam. The present work provides the investigations on the difference of tensile fracture behavior between the nickel foam and the dense metal nickel, as well as that of the corresponding samples in various cases with different tensile velocities. It is found that the porosity can make a remarkable decrease of the apparent strain at the maximum load and a significant increase of the macroscopical brittleness for the metallic nickel under tension.

Details

Multidiscipline Modeling in Materials and Structures, vol. 12 no. 1
Type: Research Article
ISSN: 1573-6105

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Article
Publication date: 2 November 2018

Banjara Kotresha and N. Gnanasekaran

This paper aims to discuss about the two-dimensional numerical simulations of fluid flow and heat transfer through high thermal conductivity metal foams filled in a…

Abstract

Purpose

This paper aims to discuss about the two-dimensional numerical simulations of fluid flow and heat transfer through high thermal conductivity metal foams filled in a vertical channel using the commercial software ANSYS FLUENT.

Design/methodology/approach

The Darcy Extended Forchheirmer model is considered for the metal foam region to evaluate the flow characteristics and the local thermal non-equilibrium heat transfer model is considered for the heat transfer analysis; thus the resulting problem becomes conjugate heat transfer.

Findings

Results obtained based on the present simulations are validated with the experimental results available in literature and the agreement was found to be good. Parametric studies reveal that the Nusselt number increases in the presence of porous medium with increasing thickness but the effect because of the change in thermal conductivity was found to be insignificant. The results of heat transfer for the metal foams filled in the vertical channel are compared with the clear channel in terms of Colburn j factor and performance factor.

Practical implications

This paper serves as the current relevance in electronic cooling so as to open up more parametric and optimization studies to develop new class of materials for the enhancement of heat transfer.

Originality/value

The novelty of the present study is to quantify the effect of metal foam thermal conductivity and thickness on the performance of heat transfer and hydrodynamics of the vertical channel for an inlet velocity range of 0.03-3 m/s.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 1
Type: Research Article
ISSN: 0961-5539

Keywords

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