• Steel and Composite Structures
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• 제15권3호
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• pp.267-279
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• 2013

This article describes a simple and cost effective fabrication procedure by using hand lay-up technique that is employed for the manufacturing of thin-walled axi-symmetric composite shell structures with carbon, glass and hybrid woven fabric composite materials. The hand lay-up technique is very commonly used in aerospace and marine industries for making the complicated shell structures. A generic fabrication procedure is presented in this paper aimed at manufacture of plain Carbon Fabric Reinforced Plastic (CFRP) and Glass Fabric Reinforced Plastic (GFRP) shells using hand lay-up process. This paper delivers a technical breakthrough in fabrication of composite shell structures without any joints and wrinkling. The manufacture of stiffened CFRP shells, laminated CFRP shells and hybrid (carbon/glass/epoxy) composite shells which are valued by the aerospace industry for their high strength-to-weight ratio under axial loading have also been addressed in this paper. A fabrication process document which describes the major processing steps of the composite shell manufacturing process has been presented in this paper. A study of microstructure of the glass fabric/epoxy composite, carbon fabric/epoxy composite and hybrid carbon/glass/fabric epoxy composites using Scanning Electron Microscope (SEM) has been also carried out in this paper.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.60-64
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• 2001

In this paper, the tension-compression fatigue test method and the fatigue life characteristics of carbon fabric/epoxy laminate coupon are presented. To avoid the buckling during the compression, a proper design for the test coupons is essential. The critical buckling loads for the coupons are calculated by assuming the coupons as columns under two types of fixed conditions. The first is that both ends of each coupon are perfectly clamped, the second is that both ends of each coupon are simply supported. The strain-load curves are obtained by compressing the representative coupons, on each surface of which a strain gage is attached. The buckling loads obtained from the tests are all between the two calculated critical buckling loads. All the coupons are broken by the compression during the fatigue tests. It is estimated to be the reason that the fatigue load causes delamination before the eventual failure of each coupon, and sequentially the micro-buckling in the delaminated region drives each coupon into fatigue failure during the compression. The S-N curve, the fatigue life characteristics of carbon fabric/epoxy is obtained.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.56-59
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• 2002

This paper presents a study on the permittivities of the E-glass fabric/epoxy composite laminates containing carbon black dispersions at microwave frequency. Measurement showed that the complex permittivities of the composites depend strongly on the natures and concentrations of the carbon black dispersion. A new scheme to obtain a mixing law for the estimation of complex permittivity is proposed. The experimental values of the complex permittivities were compared to those calculated. Simultaneously, the complex permittivity of carbon black itself was also calculated by the scheme.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 추계학술발표대회 논문집
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• pp.256-259
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• 2005

Mixed-mode interlaminar fracture toughness of carbon fabric/epoxy composites, which are applicable to tilting train carbody, was evaluated through the MMB (Mixed-mode bending) test. Specimens were made of CF3327 plain woven fabric with epoxy and a starter delamination at one end was made by inserting Teflon film with the thickness of 12.5 μ m. Mixed-mode interlaminar fracture test was conducted for 6 types of specimens with the mode II ratio of 20 ,35, 50, 65, 80, 90%. Also crack propagating behaviors and fractured surfaces were examined through an optical travelling scope and a scanning electron microscope, respectively.

• 대한기계학회논문집A
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• 제34권2호
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• pp.203-209
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• 2010

본 연구는 철도차량에 적용되는 직물 유리섬유/에폭시 적층 복합재의 피로특성 및 피로수명에 대해 평가하였다. 이때, 피로시험은 0.1의 응력비(R)와 5Hz의 주파수에서 인장-인장 하중 조건이 고려되었으며, 시험편은 카본/에폭시 플라이가 보강된 시험편과 보강되지 않은 시험편 두 가지 타입을 고려하였다. 또한, 직물 유리섬유/에폭시 적층 복합재의 피로수명을 평가하기 위해 철도차량 차체와 언더프레임에 주로 사용되는 알루미늄 6005와 비교하였다. 본 연구를 통하여 3장의 카본/에폭시 플라이가 보강된 직물 유리섬유/에폭시 적층 복합재 시험편이 보강되지 않은 기본 시험편보다 피로강도 및 피로수명이 크게 향상됨을 확인하였다.

• Composites Research
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• 제15권2호
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• pp.18-23
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• 2002

군사적 목적뿐만 아니라 상업적 목적에서도 레이더나 기타 전자파를 방출하는 기기들로부터 생성되는 전자파의 흡수 또는 차폐는 매우 중요한 일이다. 본 연구에서는 다른 유전적 성질을 가지는 복합재층을 배열하여 전자기파의 반사를 최소화하는 연구를 수행하였다. Glass fabric/epoxy에 전도성을 가지는 카본블랙 분체를 혼합한 복합재와 Carbon fabric/epoxy 복합재 대만 유전성질을 측정하였고, 이를 이용하여 X-band(8.2 GHz-l2.4GHz)에 대한 전자기파 반사의 최소화 구조를 구성하였다. 두께2.6mm의 다층 구조로 최대 30dB 이상의 반사 손실과 최대 흡수 주파수로부터 2GHz 주파수 대역에 걸쳐 10dB이상의 반사손실을 일으킬 수 있었다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.239-246
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• 2009

The Mode I interlaminar fracture toughness of woven fabric carbon/epoxy and glass/epoxy composites for a train carbody was measured and FEM analysis was conducted. The woven fabric epoxy composite manufactured by hand lay-up, has high stiffness and strength, good resistance for impact, fatigue, corrosion and in-plane failure. The DCB(Double Cantilever Beam) specimen made of woven fabric epoxy composite had the size of 180mm $\times$ 25mm $\times$ 5mm and the insert of 65mm. The Mode I interlaminar toughness of specimen was measured according to ASTM 5528-01. The crack propagation behavior of the DCB specimen was simulated using FEA with cohesive elements that model the adhesive layer between woven fabric plies.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.105-108
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• 2002

Materials, matrices mixed with various kinds of conductive or magnetic powder, such as ferrite, have been used as the electromagnetic wave absorbing ones, so called RAM(radar absorbing material). The structure that does not only have electromagnetic waves absorbing property like RAM but also supports loads is called RAS(radar absorbing structure). One of the existing manufacturing process of RAS is to compound with conductive powders the glass fiber-reinforced composite with good permeability and the ability to support loads. The process, however, causes a number of problems, such as the degradation in the mechanical properties of the composite, especially, interlamina shear strength. In this study, mechanical properties of glass fabric/epoxy composite containing 7wt% carbon black powders were measured and compared with pure glass fabric/epoxy composites.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1322-1325
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• 2005

The main objectives of this research work are to develop conductive glass fiber woven roving and carbon fiber unidirectional fabric composite materials and to determine their electromagnetic shielding effectiveness(EMSE). Epoxy is the matrix phase and glass, carbon fiber are the reinforcement phase of the composite material. Carbon black are incorporated as conductive fillers to provide the electromagnetic shielding properties of the composite material. The amount of carbon black in the composite material is varied by changing the carbon black composition, woven roving and unidirectional (fabric) structure. The EMSE of various fabric composites is measured in the frequency range from 300MHz to 800MHz. The variations of EMSE of woven roving and unidirectional composites with fabric structure, metal powder composite are described. Suitability of conductive fabric composites for electromagnetic shielding applications is also discussed.

• Composites Research
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• 제14권6호
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• pp.38-46
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• 2001

본 연구에서는, 전자파 흡수능을 가진 경사 복합재료 적층판를 설계할 수 있는 최적화 코드를 개발하였다. 또한, 유리 섬유/에폭시 직조 적층판, 알루미늄 첨가물을 함유간 유리섬유/에폭시 직조 적층판과 카본/에폭시 직조 적층판의 유전율을 구하고, 최적화 로드를 이용하여 3층형 전자파 흡수 복합재료 적층판을 개발하였다. 실험에 사용된 복합재료 적층판은 모두 전자기적으로 면내등방성을 가지며 따라서, 동축선과 망분석기를 이용하여 유전율을 측정하였다. 이 로드는 전자기적으로 직교이방성을 가지는 고분자기지 복합재료의 적층각을 포함한 다양한 변수를 고려할 수 있다.