• Title/Summary/Keyword: Sandwich composites

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A Study on Flexural Behaviors of Sandwich Composites with Facesheets of Unequal Thickness (면재 두께가 다른 샌드위치 복합재의 굽힘 거동 연구)

  • Shin, Kwang-Bok;Lee, Jae-Youl;Ryu, Bong-Jo;Lee, Sang-Jin
    • Journal of the Korean Society for Railway
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    • v.10 no.2 s.39
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    • pp.201-210
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    • 2007
  • Sandwich composites made of glass fabric epoxy facesheets with aluminum honeycomb core or balsa core is considered for the structural design of bodyshell of a Korean Low Floor Bus. Initially, in order to select the optimal facesheet and core materials in design stage, the flexural response of a sandwich composite is a critical importance. In this study, theoretical formula which could easily and quickly evaluate and obtain the flexural responses such as deflection and flexural stiffness of a sandwich composite subjected to external load was established. This theory could calculate the flexural responses of sandwich composites with narrow as well as wide width and with facesheets of unequal thickness, and also distinguish between the bending and shear effects of deflection. Finite element analysis using ANSYS V10.0 was used to offer the best elements for real sandwich composites, and flexural test according to ASTM C393 was conducted to compare with the results of theoretical formula and finite element analysis. The results show that the flexural responses of sandwich composites using proposed theoretical formula is in good agreement with those of experiment and finite element method.

A Study on the Modular Design of Hybrid Lightweight Carbody Structures Made of Sandwich Composites and Aluminum Extrusion (샌드위치 복합재와 알루미늄 압출재를 적용한 하이브리드 경량 차체 구조물의 모듈화 설계 연구)

  • Jang, Hyung-Jin;Shin, Kwnag-Bok;Han, Seong-Ho
    • Proceedings of the KSR Conference
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    • 2011.10a
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    • pp.2644-2649
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    • 2011
  • The purpose of this study is to propose the modular design of hybrid lightweight carbody structures made of sandwich composites and aluminum extrusion. The sandwich composites were used for secondary structures to minimize the weight of carbody, and the aluminum extrusions were applied to primary structures to improve the stiffness of carbody and manufacturability. Key requirements were defined for the modular design of hybrid carbody, and the applied parts of sandwich composites were determined through the topology optimization analysis. Consequently, feasibility of enhancing mass saving and maintainability in modular hybrid carbody design were presented, comparing with the carbody structures made of aluminum extrusion or sandwich composites only.

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Impact Behaviors of Stitched Sandwich Composites Under Low Energy Impact Using Drop Weight Impact Tester (고낙하추 충격시험기를 이용한 스티칭된 샌드위치 복합재의 저에너지 충격거동 연구)

  • 윤성호;이상진;조세현
    • Composites Research
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    • v.12 no.5
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    • pp.54-64
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    • 1999
  • This study investigated the impact behaviors of the stitched sandwich composites under the low energy impact by the use of drop weight impact tester. These sandwich composites condidted of the glass fabric faces with a urethane foam core. The upper face and the lower face were stitched to combinr through the core thickness direction using the polyester reinforcements. Four types of the stitched sandwich composites, each having a different core thickness, were tested to determine the effects of the core thickness. The impact conditions were changes with the variations of the mass and drop height of the impact tup. The test results showed that the core thickness and the impact condidtions such as the drop height and the mass of the impact tup affected the impact force, the contact time, and the strain behaviors of the stitched sandwich composites. The stitched sandwich composites are able to avert the damage and also maintain the structural integrity even thouth the presence of the damage owing to the through-the-thickness reinforcements. However, it is important to improve the wetting ability of the stitched reinforcements so that the conventional structures are substituted for the stitched sandwich composites effectively.

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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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Lightweight Design of Car Bodies for Double Deck High-Speed Trains (2층 고속열차 차체 구조물의 경량화 설계)

  • Kang, SeungGu;Shin, KwangBok;Ko, TaeHwan;You, WonHee
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.24 no.2
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    • pp.177-185
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    • 2015
  • This paper describes a weight-reduction design method for the car bodies of a double deck high-speed train (service speed of 300 km/h). The method uses lightweight materials and a topology optimization technique. In this study, aluminum extrusions and sandwich composites were selected as the best materials to reduce the weight of the car body. The topology optimization technique was used to determine which car body parts could be made of the sandwich composites to achieve additional weight savings. The results of the topology optimization analysis showed that sandwich composites could be used for secondary car body members such as the roof and the second underframe. Also, it was found that a car body composed of aluminum extruded parts and sandwich composites could weigh up to 14% less than a car body made of only aluminum extrusions.

Parametric Study on the Design of Sandwich Beams and Plates for Machine Tool Structures (공작기계를 위한 보와 평판의 샌드위치 구조 설계에 관한 파라메트릭 연구)

  • Kim, Dae-Il;Chang, Seung-Hwan
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.15 no.1
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    • pp.39-48
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    • 2006
  • In this paper, polymer composites based sandwich structures like beams and plates are optimised by using parametric study. The structures are composed of fibre reinforced composites for facial material and resin concrete and PVC foam for core materials. The stacking sequences and thickness of the composites are controlled as major parameters to find out the optimal condition for machine tool components. For the plate structure of machine tool bed composites-skined sandwich structure which has several ribs are proposed to enhance bending stiffnesses in two major directions at the same time. Dynamic robustness of a machine tool structure is investigated using modal analysis. From the results optimal configuration and materials for high precesion machine tools are proposed. And the plate was made of fiber reforced composite material and PVC foam.

Parametric study on design of sandwich structures composing of fibre reinfoced composites, polymer foam and resin concrete (섬유강화 복합재료, 고분자 포움 및 레진 콘크리트로 구성된 샌드위치 구조 설계를 위한 파라메트릭 연구)

  • Kim D.I.;Chang S.H.
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2005.05a
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    • pp.429-434
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    • 2005
  • In this paper sandwich structures like beams and plates are optimised by using parametric study. The structures are composed of fibre reinforced composites for facial material and resin concrete and PVC foam for core materials. The stacking sequences and thickness of the composites are controlled as major parameters to find out the optimal condition for machine tool components. For the plate structure for machine tool bed composites-skined sandwich structure which has several ribs are proposed to enhance both directional bending stiffnesses at the same time. From the results optimal configuration and materials for high precesion machine tools are proposed.

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A Study on Material Damping of the $0^0&90^0$ Laminated Composite Sandwich Cantilever Beam inserted with Viscoelastic layer (점탄성층을 삽입한 $0^0&90^0$ 섬유강화 복합재료의 감쇠계수에 대한 연구)

  • Yim, Jong-Hee;Seo, Yun-Jong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.11a
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    • pp.345-348
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    • 2004
  • In this paper it is to establish a comprehensive model for predicting damping in sandwich Laminated composites on the basis of strain energy method. In this model, the effect of transverse shear on the material damping has been considered with in-plane stresses. Results showed that the viscoelastic core thickness in the sandwich beam and the Length of a beam have a high impact on the material damping. The transverse shear appears to be highly influenced by the damping behavior in $0^0$ laminated sandwiched composites. However, it is Little influenced by that in $90^0$ laminated sandwiched composites.

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A Study on Flame Retardant Treatment on Bamboo Nonwoven Fabric and Manufacturing of Sandwich Structure Composites (대나무 섬유의 난연화 및 샌드위치 구조 복합재료 제조연구)

  • Lee, Dong-Woo;Prabhakar, M.N.;Song, Jung-Il
    • Composites Research
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    • v.33 no.6
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    • pp.408-414
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    • 2020
  • The present engineering sector focused on the sandwich composites and almost covered all engineering fields because of decent mechanical properties with a lightweight structure. It mainly consists of high strength fiber skin and porous structure core like corrugated, honeycomb, balsa wood, and foams which is playing a pivotal role in weight reduction. Recently researchers attention grabbed by Natural fiber sandwich composites due to biodegradability, renewable, low-cost, and environmentally friendly. However special focus is highly needed towards the flammability behavior of natural fibers used as reinforcement for composites. Herein, for the first time, the flame retardant natural fiber sandwich composite was fabricated by using flame retardant treated bamboo fabric and vinyl ester via the VARTM process. The impact of flame retardant treated bamboo fabric on mechanical and flame retardant properties were studied. The results concluded that the fabricated bamboo sandwich composites show structurally lightweight with significant mechanical strength and feasibility with respect to the flame.

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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