• Title/Summary/Keyword: Foam structure

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Effects of Anisotropic Properties of Composite Skins on Electromagnetic Wave Propagation in the Foam Core Sandwich Structures (폼 코어 샌드위치 구조물에서 복합재료 스킨의 이방성 특성이 전자기파 투과 특성에 미치는 영향에 관한 연구)

  • 신현수;전흥재
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.234-237
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    • 2001
  • In this study, efforts were made to understand the propagation of electromagnetic wave through the foam core sandwich structure by the analytical model. Foam core sandwich structure is composed of glass/epoxy composite skins and foam core. Transmittance and reflectance of the arbitrary linearly polarized incident TEM waves through the unidirectional composites, foam and foam core sandwich structures were determined as functions of thickness, fiber orientation of composites, incident angle and polarization angle by the analytical model. From the results of the analysis, the general tendency of transmittance and reflectance of electromagnetic wave through composites, foam and foam core sandwich structures was obtained.

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Numerical Analysis of Cyclic Deformation of Polymer Foam Film Using Stretched Truncated Octahedron Model (모서리가 제거된 팔면체 인장모델을 이용한 다공성 폴리머 박막의 반복변형거동 수치해석)

  • Yoo, Ui-Kyung;Lee, Young-Seog
    • Journal of the Korean Society for Precision Engineering
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    • v.27 no.3
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    • pp.104-110
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    • 2010
  • Cyclic deformations of polymer foam film are simulated using the finite element method. Material of polymer foam film is polypropylene (PP). The calculated polymer foam film is micro-scale thin film has cellular structure. The polymer foam film is used in ferro-electret applications. The polymer foam film is idealized to one cell structure as lens shaped stretched truncated octahedron model. Cyclic deformation is performed by uniaxial stretching. Stretching direction is perpendicular to plane of cellular film. Various cyclic strain amplitudes, pore wall thicknesses, pore shape are investigated to find deformation tendency of cellular structure. Consequently, cellular structure has various macroscopic stresses on cyclic deformation with various pore thickness and pore shape.

Electrochemical Properties of 3D Cu-Sn Foam as Anode for Rechargeable Lithium-Ion Battery (3D-foam 구조의 구리-주석 합금 도금층을 음극재로 사용한 리튬이온배터리의 전기화학적 특성 평가)

  • Jung, Minkyeong;Lee, Gibaek;Choi, Jinsub
    • Journal of the Korean institute of surface engineering
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    • v.51 no.1
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    • pp.47-53
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    • 2018
  • Sn-based lithium-ion batteries have low cost and high theoretical specific capacity. However, one of major problem is the capacity fading caused by volume expansion during lithiation/delithiation. In this study, 3-dimensional foam structure of Cu-Sn alloy is prepared by co-electrodeposition including large free space to accommodate the volume expansion of Sn. The Cu-Sn foam structure exhibits highly porous and numerous small grains. The result of EDX mapping and XPS spectrum analysis confirm that Cu-Sn foam consists of $SnO_2$ with a small quantity of CuO. The Cu-Sn foam structure electrode shows high reversible redox peaks in cyclic voltammograms. The galvanostatic cell cycling performances show that Cu-Sn foam electrode has high specific capacity of 687 mAh/g at a current rate of 50 mA/g. Through SEM observation after the charge/discharge processes, the morphology of Cu-Sn foam structure is mostly maintained despite large volume expansion during the repeated lithiation/delithiation reactions.

Characteristics of Micro-pore Structure of Foam Composite using Palm-based Activated Carbon (야자계 활성탄을 활용한 폼 복합체의 미세기공 구조특성)

  • Choi, Young-Cheol;Yoo, Sung-Won
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.5
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    • pp.157-164
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    • 2021
  • Recently, a number of studies have been conducted on photocatalysts and adsorbents that can remove harmful substances to improve environmental problems related to fine particles. In this study, a porous foam composites were fabricated using palm-based activated carbon having a large amount of micro-pores and foam concrete with a significantly larger total pore volume compared to general construction materials. To evaluate the adsorption potential of fine particles, the pore structure of the foam composites were analyzed. For the analysis of the pore structure of the foam composite, BET and Harkins-jura theory were applied from the measured nitrogen adsorption isotherm. From the results of the analysis, the specific surface area and micro-pore volume of the foam composite containing activated carbon increased significantly compared to Plain. As thereplacement of activated carbon increased, the specific surface area and micro-pore volume of the foam composite tended to increase. It seems that the foam composite has high adsorption performance for gaseous fine particle precursor such as nitrogen oxides.

Modeling of the Elasto-plastic Deformation Behavior of Two-Dimensional Anisotropic Foam under Compressive Loads using Voronoi Cells (보로노이 셀을 이용한 2 원 비등방성 폼 구조 모델링 및 탄소성 압축변형 해석)

  • Han, Won-Hee;Choi, Byoung-Ho;Kim, Il-Hyun;Lee, Jeong-Moo
    • Journal of the Korean Society for Precision Engineering
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    • v.29 no.7
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    • pp.785-792
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    • 2012
  • Foam structure is usually hard to model due to the complexity of the geometry of cells. So, many simplified models to represent complicated foam structures have been proposed, but most of them are not actually describe the random feature of the cell structure well. So, in this study, two dimensional isotropic and anisotropic closed cell structures of the foam were modeled using the concept of Voronoi cells. The elasto-plastic deformation behavior under compressive loads was investigated by finitie element analysis, and the results were compared with ideal honeycomb structure. In addition, the effect of anisotropy of Voronoi cell structures of the foam on Young's modulus and yield stress under compressive loads was studied.

The Effects of Cell Sizes on Compression and Bending Strength of Aluminum Material (알루미늄 소재의 미세 기공 크기가 압축 및 굽힘 강도에 미치는 영향)

  • 전용필;강충길
    • Transactions of Materials Processing
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    • v.11 no.8
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    • pp.701-709
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    • 2002
  • Aluminium foam material is highly porous material, which has the complicated cellular structure defined by randomly distributed pores in metallic matrix. This structure gives the characteristic properties which cannot be achieved by any other conventional processes. As the properties of aluminium foam material significantly depend on its porosity, a desired profile of properties can be tailored by changing the foam density. But various defects lead to undesirable effects on the mechanical properties. Mechanical properties are dependent on cell sizes and aspect ratios. Therefore, this paper presents the effects of various processing parameters of various parameters on the mechanical properties. For the sake of this, combined stirring was used to fabricate aluminum foam materials by the parameters. Compression and bending tests were performed to investigate the effects of cell sizes and aspect ratios on the mechanical properties.

Characterization of Elastic Modulus of Kelvin Foam Using Elastic Structural Model and Ultrasound (초음파와 탄성 구조 모델을 이용한 캘빈 폼 재료의 탄성계수 평가)

  • Kim, Woochan Ethan;Kim, Nohyu
    • Journal of the Korean Society for Nondestructive Testing
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    • v.36 no.6
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    • pp.474-482
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    • 2016
  • A Kelvin foam plate - widely used in the energy and transport industries as a lightweight structural material - was examined to estimate its Young's modulus using ultrasound. An isotropic tetrakaidecahedron foam structure was designed in SolidWorks and printed using 3D printer with an ABS plastic material. The 3D printed foam structure was used to build a foam plate with a 14 mm thickness ($50mm{\times}100mm$ in size) for the ultrasonic test. The Kelvin foam plate, a significantly porous medium, was completely filled with paraffin wax to enable the ultrasound to penetrate through the porous medium. The acoustic wave velocity of the wax-filled Kelvin foam was measured using the time of flight (TOF) method. Furthermore, the elastic modulus of the Kelvin foam was estimated based on an elastic structural model developed in this study. The Young's modulus of the produced Kelvin foam was observed to be approximately 3.4% of the bulk value of the constituent material (ABS plastic). This finding is consistent with experimental and theoretical results reported by previous studies.

Studies on the Water Resistance Properties of the Polyurethane Foam Silicone Foal Control Agent according to the Type of Silicone Foam Stabilizer (실리콘 정포제의 종류에 따른 폴리우레탄 폼 지수제의 내수성 특성에 관한 연구)

  • Kim, Keun-Hur;Kim, Hyun-Min;Kim, Sung-Rae;Kim, Young-Geun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.20 no.2
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    • pp.60-66
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    • 2016
  • Polyurethane foam index a of the cell structure and the absorption change by using the foam stabilizer of six to investigate the polyurethane foam index producing the agent to the siloxane analyzed with silicon foam stabilizer with FE-SEM in accordance with the characteristics of the silicon-based foam stabilizer cell structure of the primary DC-193 on the chain ends is PO n dog bond, DC-2585, DC-5125, DC-198 has been confirmed as a close cell, silicone surfactant is combined EO n dog to a siloxane main chain terminus DC-5043 and DC-5598 that appeared to open cell structure. In addition, most absorption of the DC-5043 appeared was the size of the open cell greatest formed by the absorption of the cell structure change this absorption of the size of the close cell most detailed and uniform DC-193 appeared small household water-resistant best many showed. The performance test of the water was found to be excellent.

Electromagnetic Wave Propagation in Anisotropic Composite Structures (이방성 복합재료의 전자기파 투과특성)

  • 전흥재;신현수
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2002.04a
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    • pp.407-414
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    • 2002
  • The knowledge of interaction of electromagnetic waves in composite structures is important for designing the shielding structure for antenna such as radome. Recently, radomes are constructed in the form of foam core sandwich structures that have many mechanical advantages such as high strength, long fatigue life, low density and adaptability to the intended function of structure. However, the propagation of electromagnetic waves is affected by high anisotropic permeability and loss tangent of the composite skin. In this study, the analytical model to understand the propagation of electromagnetic waves in the anisotropic composites and foam core sandwich structures with composite skins was proposed. Numerical analyses of unidirectional composites and foam core sandwich structure as a function of incident angle were performed. From the results of analysis, the general tendencies of transmittance of electromagnetic wave through composites and foam core sandwich structure were obtained.

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A Numerical Study on The Three Point Bending Behavior of Aluminum Foam Filled Stainless Steel Tube (알루미늄 폼으로 충진된 스테인레스 관의 3 점 굽힘 특성에 관한 수치적 연구)

  • Ha, San;Kim, Am-Kee;Cheon, Seong-Sik;Lee, Chang-Hun;Lee, Hyo-Jin;Cho, Seong-Seock
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.388-393
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    • 2004
  • A comprehensive numerical study on the three point bending behavior of Aluminum foam-filled stainless steel tube has been performed. Aluminium alloy foams with various densities were produced and their mechanical properites were evaluated. Finite element(FE) analysis of three point bending test was performed to evaluate bending behavior of foam filled cylindrical structures. Results showed that foam filling offered remarkable increase of bending resistance and enhanced the crashworthiness of the structure. It turned out to prevent the inward fold formation at the compression flange, resulted into the multiple propagating folds and increased the load carrying capacity.

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