• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 춘계학술발표대회 논문집
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• pp.89-92
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• 2002

Traditionally unidirectional laminated composite which are characterized by high specific stiffness and strength were used for structural application. But theses composites are highly susceptible to impact damage because of lower transverse tensile strength. The main failure modes of laminated composite are fiber breakage, matrix cracking and delamination for low velocity impact. The modified failure criterions are implemented to predict these failure modes with finite element analysis. Failure behavior of the woven fabric laminated composite which is used in forehead part of subway to lighten weigh has been studied. The new failure criterions are in good agreement with experimental results and can predict the failure behavior of the woven fabric composite plate subjected to low velocity impact more accurately.

• Steel and Composite Structures
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• 제34권2호
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• pp.299-308
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• 2020

This study aims to carry out the experimental and numerical investigation on the flexural behavior of sandwich honeycomb composite (SHC) beams reinforced with novel triaxially woven fabric composite skins. Different stacking sequences of the carbon fiber reinforcement polymer (CFRP) laminate; i.e., 0°-direction of TW (TW0), 0°-direction of UD (UD0), and 90°-direction of UD (UD90) were studied, from which the flexural behavior of SHC beam behaviors reinforced with TW0/UD0 or TW0/UD90 novel laminated skins were compared with those reinforced with UD0/90 conventional laminated skins under four-point loading. Generally, TW0/UD0 SHC beams displayed the same flexural stiffness as UD0/90 SHC beams in terms of load-deflection relationships. In contrast, TW0/UD90 SHC beams showed a 70% lower efficiency than those of UD0/90 SHC. Hence, the TW0/UD0 laminate arrangement is more effective with a mass reduction of 39% compared with UD0/90 for SHC beams, although their stiffness and shear strength are practically identical.

• Steel and Composite Structures
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• 제17권6호
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• pp.825-834
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• 2014

This manuscript presents an experimental investigation on the effect of Multi-walled carbon nanotubes (MWCNTs) addition on the tensile, flexural and impact properties of woven Kevlar fabric reinforced epoxy composites. MWCNTs were dispersed in the epoxy resin by sonication technique and the samples were fabricated by hand layup laminating procedure. Scanning electron microscopy (SEM) was used to characterize the microstructure of produced samples. The effects of adding small amounts (${\leq}1%$) of MWCNT on the tensile, flexural and impact (Izod) behaviors of laminated composites were analyzed. Results revealed that MWCNTs enhanced the Young's modulus up to 20%, bending modulus up to 40%, and impact strength up to 45% in comparison with woven Kevlar fabric/epoxy composites. It was found that the maximum improvements in mechanical properties were happened for 0.5 wt.% MWCNT.

• 한국재료학회지
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• 제29권1호
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• pp.43-51
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• 2019

Nacre of abalone shell features a "brick-and-mortar" microstructure, in which micro-plates of calcium carbonate are bonded by nanometers-thick layers of chitin and proteins. Due to the microstructure and its unique toughening mechanisms, nacre possesses an excellent combination of specific strength, stiffness and toughness. This study deals with the possibility of using nacre fragments obtained from abalone shell for making a bulletproof armor system. A composite plate laminated with abalone shell fragments is made and compression and bend tests are carried out. In addition, a bulletproof test is performed with hybrid armor systems which are composed of an alumina plate, a composite plate, and aramid woven fabric to verify the ballistic performance of nacre. The compressive strength of the composite plate is around 258.3 MPa. The bend strength and modulus of the composite plate decrease according to the plate thickness and are about 149.2 MPa and 50.3 GPa, respectively, for a 4.85 mm thick plate. The hybrid armor system with a planar density of $45.2kg/m^2$, which is composed of an 8 mm thick alumina plate, a 2.4 mm thick composite plate, and 18 layers of aramid woven fabric, satisfy the NIJ Standard 0101.06 : 2008 Armor Type IV. These results show that a composite plate laminated with abalone shell fragments can be used for a bulletproof armor system as an interlayer between ceramic and fabric to decrease the armor system's weight.

• 한국의류산업학회지
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• 제22권1호
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• pp.112-118
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• 2020

This paper examined the water repellency, water proofing and water vapor permeability of twelve types of woven fabrics for sports wear clothing. Their physical properties were compared and discussed with the fabric structural parameters and surface finishing effect. A water repellent property of 100% was obtained in the coated or laminated water repellent finished fabrics; in addition, cotton/nylon breathable composite fabrics treated with a laminated finishing and with low fabric density showed a 90% water repellency. Water proofing fabric above 6,000 mm H₂O hydraulic pressure was achieved by coated or laminated finishing; however, high density fabric or medium-level coated fabrics exhibited 100% water repellent and low water proofing characteristics. Superior water vapor permeability characteristics with good water repellency and proofing properties were achieved at the 2.5 layered low density and with 0.7 - 0.9 cover factor nylon fabrics treated with hydrophilic laminated finishing. The regression analysis for examining the effects of fabric structural parameters and surface finishing such as coating and laminating to the water vapor permeability exhibited a high determination coefficient of fabric structural parameters of 63.5%; in addition,, main factors among fabric structural parameters appeared to be cover factor and fabric thickness per weight. Coating and Laminating factors exhibited determination coefficient of water vapor permeability parameters of 36.5%.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.437-440
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• 2010

이 논문은 발사체 노즐에 사용되는 내열성 재료인 C/SiC에 대한 이방성 물성을 예측하는 방법으로, 평면 방향의 실험 데이터를 이용해서 9개의 엔지니어링 물성을 간단하고 효과적으로 계산하는 준 이론적 접근에 대해 설명하였다. 이 방법은 C/SiC 복합재료를 직조 보강재의 굴곡율에 따라 세 층으로 이상화 하여, 고전 적층 평판이론으로 계산한다. 평면 방향으로 실행된 실험 데이터와 직조 구조물의 굴곡율을 초기 데이터로 이용하며, 측정이 어려운 두께 방향의 물성을 효과적으로 얻을 수 있었다. 예제를 통하여 이 방법의 유용성을 증명하였다.

• 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.

• 오토저널
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• 제13권5호
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• pp.65-72
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• 1991

This paper presents the results of static crushing test that was conducted to characterize the energy absorption and collapse characteristics of composite box tubes. Fifteen specimens were fabricated with woven fabric prepreg using [0/90] glass/epoxy and were autoclave cured. Quasistatic compression test was performed on them. Collapse mode and energy absorption capacity vary significantly as a function of the thickness and length of a square side of composite box tube.

• 한국자동차공학회논문집
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• 제1권3호
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• pp.118-126
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• 1993

Static and dynamic crushing behaviors of composite box tube show the difference with those of metal tube. This paper investigates the characteristics of static and dynamic crushing test which were conducted to characterize the energy absorption and collapse mode of composite box tubes. Sixteen kinds of tube specimens were fabricated from[0/90] woven Glass/Epoxy fabric and autoclave cured. Axial crushing tests were performed using Instron and Dynatup Impact Tester. It is shown that collapse mode and energy absorption capacity can vary according to the aspect ratio, length, loading rate, lay-up direction of fabric, and trigger geometry of the composite box tube.

• 한국기계가공학회지
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• 제18권1호
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• pp.59-64
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• 2019

In recent years, the HP-CRTM method, which has the ability to produce carbon fiber-reinforce plastic composites at high speeds, has come into the spotlight in the automotive parts industry, which demands high productivity. Multi-axial carbon fabric, an intermediate material used in this HP-CRTM molding process, consists of layered fibers without crimp, which makes it better in terms of tensile and shear strength than the original woven fabrics. The NCF (non-crimp fabric) can form the layers of the carbon fiber, which have different longitudinal and lateral directions, and ${\pm}{\theta}$ degrees, depending on the product's properties. In this research, preforms were made with carbon fibers of ${\pm}45^{\circ}$ and $0/90^{\circ}$, which were lamination structures under seven different conditions, in order to create the optimal laminated structure for automobile reinforcement center floor tunnels. Carbon fiber composites were created using each of the seven differently laminated preforms, and polyurethane was used as the base material. The specimens were manufactured in accordance with the ASTM D3039 standards, and the effect of the NCF lamination structure on the mechanical properties was confirmed by a tensile test.