• Title/Summary/Keyword: Composite Material

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Pooling-Across-Environments Method for the Generation of Composite-Material Allowables (환경조건간 합동을 이용한 복합재료 허용치 생성 기법)

  • Rhee, Seung Yun
    • Journal of Aerospace System Engineering
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    • v.10 no.3
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    • pp.63-69
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    • 2016
  • The properties of composite materials, when compared to those of metallic materials, are highly variable due to many factors including the batch-to-batch variability of raw materials, the prepreg manufacturing process, material handling, part-fabrication techniques, ply-stacking sequences, environmental conditions, and test procedures. It is therefore necessary to apply reliable statistical-analysis techniques to obtain the design allowables of composite materials. A new composite-material qualification process has been developed by the Advanced General Aviation Transport Experiments (AGATE) consortium to yield the lamina-design allowables of composite materials according to standardized coupon-level tests and statistical techniques; moreover, the generated allowables database can be shared among multiple users without a repeating of the full qualification procedure by each user. In 2005, NASA established the National Center for Advanced Materials Performance (NCAMP) with the purpose of refining and enhancing the AGATE process to a self-sustaining level to serve the entire aerospace industry. In this paper, the statistical techniques and procedures for the generation of the allowables of aerospace composite materials will be discussed with a focus on the pooling-across-environments method.

A Study for the Fire Retardant-Characteristics of Expandable Graphite Composite Materials (팽창흑연을 사용한 복합재료의 난연 특성에 관한 연구)

  • Chun, Kwan-Ok;Rie, Dong-Ho
    • Journal of the Korean Society of Safety
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    • v.32 no.3
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    • pp.28-33
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    • 2017
  • In this study, the composite material of expandable graphite was made to the material development for improving such as a composite material of the sandwich panels or material properties of a fire door and was tested by the ISO 1182, ISO 5660-1(Cone calorimeter Method). For the test, the composite material of expandable graphite, what the expandable graphite ratio was increased by respectively 0g~30g, was classified A1,A2, A3, A4, and made to the test specimens. Through cone calorimeter test, peak heat release rate(HRR) and total heat release(THR), expanded thickness and expansion rate of each composite material of expandable graphite, and fire prone crack and mass loss rate after burning was measured. Thus, the effect of the addition of the expandable graphite and whether is suitable for reference as a fire retardant, was analyzed. Consequently the correlation of THR and fire retardant performance rate was confirmed.

Mechanical strength analysis for functionally graded composite plates (경사기능 복합재료 판의 기계적 강도해석)

  • Na, Kyung-Su;Kim, Ji-Hwan
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2005.11a
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    • pp.66-69
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    • 2005
  • Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.Mechanical strength of functionally graded composite plates that composed of ceramic, functionally graded material and metal layers is investigated using 3-D finite element method. In FGM layer, material properties are assumed to be varied continuously in the thickness direction according to a simple power law distribution in terms of the volume fraction of a ceramic and metal. The 3-D finite element model is adopted by using an IS-node solid element to analyze more accurately the variation of material properties in the thickness direction. Numerical results are compared with those of the previous works. In addition, the displacements, the tensile stresses and the compressive stresses are analyzed for the variation of FGM thickness ratio and volume fraction distribution.

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Effect of Interfacial Debonding on the Material Properties of Brittle Matrix Composites (취성기지 복합재료의 물성치에 미치는 계면분리의 영향)

  • 염영진;진민철
    • Composites Research
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    • v.16 no.1
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    • pp.42-49
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    • 2003
  • Brittle matrix composites often have interfacial debonding between the fiber and matrix which may lead to strength and stiffness degradation. The effect of interfacial debonding and fiber volume fraction on the mechanical properties of composite material were studied by using finite element method. Firstly, the modelling of fiber and matrix constituting the composite material was simplified under some assumptions. Traction and displacement continuity conditions were imposed along the boundary of adjacent representative volume elements. In order to obtain the effective material properties of composite material, stiffness constants were inverted. Numerical values of longitudinal moduli in case of perfect bonding were compared with theoretical values obtained by rule of mixtures and yielded consistency. Material properties of composite with large debonding an81e were found to decrease even though the fiber volume fraction increased.

The Study on Potential Characteristics and Corona Discharge of Composite Insulating Material (복합절연재료 FRP의 코로나 대전파 전위감쇄특성에 관한 연구)

  • 이백수;신태현;김진식;강대하;이덕출
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1995.11a
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    • pp.365-368
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    • 1995
  • Charge decay, thermally stimulated current (TSC), charging and discharging currents(I) are measured for corona-charged composite insulating materials. In this study, We will make an experiment in charge decay on composite material surface, TSC, polarity effect and the others in order to analysis its mechanism. Especially, Fiber glass Reinforced Plastics(FRP) is the best composite material which has been so far. Therefore, Its worthy of notice to investigate its characteristic. And then some other materials will be focused on. This experiment measured characteristic of charge decay, dependence of discharging-time and other electrostatic characteristics on FRP.

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Large deformation analysis of inflated air-spring shell made of rubber-textile cord composite

  • Tran, Huu Nam;Tran, Ich Thinh
    • Structural Engineering and Mechanics
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    • v.24 no.1
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    • pp.31-50
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    • 2006
  • This paper deals with the mechanical behaviour of the thin-walled cylindrical air-spring shell (CAS) made of rubber-textile cord composite (RCC) subjected to different types of loading. An orthotropic hyperelastic constitutive model is presented which can be applied to numerical simulation for the response of biological soft tissue and of the nonlinear anisotropic hyperelastic material of the CAS used in vibroisolation of driver's seat. The parameters of strain energy function of the constitutive model are fitted to the experimental results by the nonlinear least squares method. The deformation of the inflated CAS is calculated by solving the system of five first-order ordinary differential equations with the material constitutive law and proper boundary conditions. Nonlinear hyperelastic constitutive equations of orthotropic composite material are incorporated into the finite strain analysis by finite element method (FEM). The results for the deformation analysis of the inflated CAS made of RCC are given. Numerical results of principal stretches and deformed profiles of the inflated CAS obtained by numerical deformation analysis are compared with experimental ones.

Statistical Characteristics of Domestic Composite Material Prepregs (국산 복합재료 프리프레그 통계적 특성)

  • Kim, Jinwon;Lee, Hosung
    • Journal of Aerospace System Engineering
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    • v.10 no.1
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    • pp.103-110
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    • 2016
  • This study shows the statistical properties of the domestic composite material prepregs test result. During the last three years(2012.5~2015.6) the prepreg specimen tests have been performed by referring to NCAMP developed test procedure which was approved by FAA. The database of (1) Carbon Tape, (2) Glass Fabric, and (3) Carbon Fabric composite material prepregs' characteristics have been established for certified aircraft structures. This qualified materials can be used for aircraft structural design through proper material equivalency procedures.

A Study on the Certification System and Development Plan of Domestic Composite Material for Aircraft Use (항공기용 국산 복합재료 인증체계 및 발전방향에 대한 연구)

  • Kim, Ilyoung
    • Journal of Aerospace System Engineering
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    • v.9 no.4
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    • pp.43-48
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    • 2015
  • This paper presents the systematic and procedural approaches to ensure the safety of the composite material domestically developed and produced, for its use in the structure of aeronautical product in accordance with the applicable international standard, and to enhance its creditability. Based on this approaches, this paper eventually proposes the practical future plan to encourage and expand the adoption of domestic composite material as part of aeronautical product by aircraft manufacturer in global market.

Microwave Properties of Organic-inorganic Composite Material Antenna with Various Fabrication Method of Conduction Material (전도체 형성 방법에 따른 유무기 복합재료 안테나의 고주파 특성)

  • Park, Sang-Hoon;Seong, Won-Mo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.9
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    • pp.832-837
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    • 2006
  • Antennas were fabricated by physical(adhesive) and chemical(deposition+plating) method on organic-inorganic composite material. And antennas were measured dielectric constant and gain. Dielectric constant of antennas were fabricated by physical method was decreased with increase of adhesive tape thickness and number of conduction material composition. But antennas were fabricated by chemical method was reached to 90 % of dielectric material. Gain of antennas were fabricated by physical method was decreased with increase of adhesive tape thickness. But they were unrelated with conduction material composition. The other side antennas were fabricated by chemical method excelled more 0.8 dBic than antennas were fabricated by physical method in gain of antenna. Finally, chemical method can expect excellent product process because it can produce smaller size, higher gain and elimination of many handworks.

Flexible Antenna Radiator Fabricated Using the CNT/PVDF Composite Film (CNT/PVDF 복합막을 이용한 유연소자용 안테나 방사체)

  • Kim, YongJin;Lim, Young Taek;Lee, Sunwoo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.28 no.3
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    • pp.196-200
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    • 2015
  • In this paper, we fabricated flexible antenna radiator using the CNT/PVDF (carbon nanotube / polyvinylidene fluoride) composite film. We used polymer film as a matrix material for the flexible devices, and introduced CNTs for adding conductivity into the film resulting in obtaining performances of the antenna radiator. Spray coating method was used to form the CNT/PVDF composite radiator, and pattern formation of the radiator was done by shadow mask during the spray coating process. We investigated the electrical properties of the CNT/PVDF composite films with the CNT concentration, and also estimated the radiator performance. Finally we discuss the feasibility of the CNT/PVDF composite radiator for the flexible antenna.