• Title/Summary/Keyword: Short fiber

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The Planar Orientation of Fibers During Compression Molding of Short-Fiber Reinforced Polymeric Composites (단섬유강화 고분자 복합재료의 압축성형에 있어서 섬유배향에 관한 연구)

  • Kim, Hyuk;Jeon, Sang-Gi;Lee, Dong-Gi;Han, Gil-Yong;Kim, E-Gon
    • Journal of Ocean Engineering and Technology
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    • v.10 no.3
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    • pp.34-43
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    • 1996
  • In this study basic equations of fiber orientations is cimpared with experimental results. It is found that fiber orientations of short fiber reinforced polymeric composite under compression molding are governed by slope of flow speed in x-y direction. Fiber orientation angle of mold is also found to increase with closure speed and the compression ratio. At the middle of the mold, the slope of flow speed is larger in x-direction than in y-direction. At the wall of the mold, the shope of flow speed in y-direction occurs due to the effect of friction, hence affects the fiber orientation. The effect of partial flow, which incurs y-direction orientation causes to increase the fiber orientation angle at the fore part of the flow.

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Sliding Wear Properties of Carbon Fiber Reinforced $Si_3N_4$ Ceramics (탄소섬유강화 질화규소 세라믹스의 마찰마모 특성)

  • Park Yi-Hyun;Yoon Han-Ki;Kim Bu-Ahn;Park Won-Jo
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2004.05a
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    • pp.347-351
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    • 2004
  • [ $Si_3N_4$ ] composites have been extensively studied for engineering ceramics, because it has excellent room and high temperature strength, wear resistance properties, good resistance to oxidation, and good thermal and chemical stability. In the present work, carbon short fiber reinforced $Si_3N_4$ ceramics were fabricated by hot press method in $N_2$ atmosphere at $1800^{\circ}C$ using $Al_2O_3\;and\;Y_2O_3$ as sintering additives. Content of carbon short fiber was $0\%,\;0.1\%\;and\;0.3\%$. The composites were evaluated in terms of density, flexural strength and elastic modulus through the 3-point bending test at room temperature. Also, The wear behavior was determined by the pin on disk wear tester using silicon nitride ball. Experimental density and flexural strength decreased with increasing content of carbon fiber. But specific modulus increased with increasing content of carbon fiber. In addition, friction coefficient and specific wear loss decreased with increasing content of carbon short fiber by reason of interfacial defects between matrix and fiber.

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Fiber Orientation of Short Fiber Reinforced Polymeric Composites Depending on Injection Mold Shape Variations (단섬유강화 고분자 복합재료에서 사출성형 형상금형 형상변화에 따른 섬유배향상태)

  • Kim, Hyuk;Han, Gil-Young;Lee, Dong-Gi
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.778-784
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    • 2001
  • Injection molding is a very important industrial process for the manufacturing of plastics objects. During an injection molding process of composites, the fiber-matrix separation and fiber orientation are caused by the flow of molten polymer/fiber mixture. As a result, the product tends to be nonhomogeneous and anisotropic. Hence, it is very important to clarify the relations between separation orientation and injection molding conditions. So far, there is no research on the measurement of fiber orientation using image processing. In this study, the effects of fiber content ratio and molding condition on the fiber orientation-angle distributions are studied experimentally. Using the image processing method, the fiber orientation distribution of weld-line parts in injection-molded products is assessed. And the effects of fiber content and injection molding conditions on the fiber orientation functions are also discussed.

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Development and Application to Fracture Mechanics of Composites with Arbitrary Fiber Size (임의형태(任意形態)의 섬유(纖維)를 가진 복합재료(複合材料) 개발(開發)과 파괴역학(破壞力學)에의 응용(應用)(I) (시편제작을 중심으로))

  • Park, Jung-Do
    • Journal of the Korean Society for Nondestructive Testing
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    • v.13 no.1
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    • pp.7-14
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    • 1993
  • In order to analyze the stress distribution and stress concentration factors in composite materials, especially, in the short fiber of the reinforced composite materials by photoelastic method, it is necessary to develop the photoelastic model material having short fibers with arbitrary size and orientation. In this paper, the orthotropic photoelastic model material having short fibers for the transparent type photoelastic device was developed by the embedded corrosion fiber method. It was found that the model material was satisfactory to the properties of photoelastic model material, and also that the embedded corrosion fiber method can be employed for developing a model material with arbitrary size and direction to analyze the stress distribution and crack problems of composite materials.

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Fatigue Crack Growth Behavior of Short fiber/Particle Hybrid Metal Matrix Composites (단섬유/입자 혼합 금속복합재료의 피로균열진전 거동)

  • Oh K.H.;Jang J. H.;Han K. S.
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.04a
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    • pp.219-222
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    • 2004
  • The effects of short fiber and particle hybrid reinforcement on fatigue crack propagation behaviors in aluminum matrix composites have been investigated. Single and hybrid reinforced 6061 aluminum containing same 20 $Al_2O_3\;volume\%$ with four different constituent ratios of short fibers and particles were prepared by squeeze casting method and tested to check the near-threshold and stable crack growth behavior. The fatigue threshold of the composites increased with portion of particle contents and showed the improved crack resistance especially in low stress intensity range. Addition of particle instead of short fiber also increased fracture toughness due to increase of inter-reinforcement distance. These increase in both fatigue threshold and fracture toughness eventually affected the fatigue crack growth behavior such that the crack growth curve shift low to high stress intensity factor value. Overall experimental results were shown that particle reinforcement was enhanced the fatigue crack resistance over the whole stress intensity factor range.

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Settlement Characteristics of Short-fiber Reinforced Soil under Simulated Railroad Loading (열차모의하중에 대한 단섬유 보강토체의 침하특성)

  • 박영곤;김정기;김현기;황선근
    • Proceedings of the KSR Conference
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    • 2002.10a
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    • pp.596-600
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    • 2002
  • To analyze the settlement characteristics of short-fiber reinforced soil(SFRS), which will be used as a new backfill material of reinforced retaining wall, under simulated railroad loading, a series of tests with loading condition of 5 Hz frequency and 500,000 cycles were performed. The materials used for tests are soils with SM or ML type, and polypropylene short-fibers with mono-filament(PPM) or fibrillated type(PPF). From the tests, average plastic settlement is low at PPF38(0.3%)(abbreviation of PPF with 38mm length and mixing ratio 0.3%), PPF38(0.5%), PPM60(0.2%) for SFRS using SM soil and at PPF38(0.3%), PPF60(0.2%) for SFRS using ML soil. Elastic settlement is low at PPM60(0.2%) for SFRS using SM soil and at PPM60(0.5%) for SFRS using ML soil.

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Fiber Orientation in Injection-Molded Short Fiber Composites with a Confocal Laser Scanning Microscope and Numerical Simulation (공초점 레이저 주사 현미경을 이용한 단섬유 복합재료 사출 성형물 내의 섬유 배열 측정 및 수치모사)

  • Lee, Kwang-Seok;Le, Seok-Won;Youn, Jae-Ryoun
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.201-204
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    • 2001
  • A Confocal Laser Scanning Microscope (CLSM) is applied to determine three-dimensional fiber orientation states in injection-molded short fiber composites. Since the CLSM optically sections the composites, more than two planes either on or below the surface of composites can be obtained. Therefore, three dimensional fiber orientation states are determined without destruction. To predict the orientation states, velocity and temperature fields are calculated by using a hybrid FEM/FDM method. The change of orientation state during packing stage is also considered by employing a compressible Hele-Shaw model. The predicted orientation states show good agreement with measured ones. However, some differences are found at the end of cavity. They may result from other effects, which are not considered in the numerical analysis.

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The Influence of Interphase Condition on Mechanical Properties of Short-Fiber Reinforced Rubber (계면상 조건이 단섬유 강화고무의 기계적 성질에 미치는 영향)

  • Ryu, Sang-Yeol;Lee, Dong-Ju
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.3 s.174
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    • pp.625-633
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    • 2000
  • The mechanical and curing properties of short nylon66 fiber reinforced Chloroprene rubber have been investigated as functions of interphase conditions and fiber content. The tensile strength exhibits a dilution effect at a low fiber content in each interphase. It is found that the interphase conditions have an important affect on the dilution ratio and critical fiber content. Double coatings of bonding agent 402 and rubber solution become the best interphase model in this study. The yield strength, tensile modulus, tear strength and fracture toughness at rupture, Jr are significantly improved due to fiber concentration.

Yarn Hairiness Affecting Fluff Generation

  • Koo, Young-Seok
    • Fibers and Polymers
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    • v.4 no.3
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    • pp.119-123
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    • 2003
  • Fluff (lint, fiber fly) generation, especially related to yarn structure, was investigated. Research centered on the fiber length related to fluff generation during the knitting process. Short fiber length composing yarn structure was a main source of the fluff shedding. High quality spun yarn with longer length of fiber was recommended to the high speed knitting industry in order to reduce process troubles such as yarn breakage, etc. but the cost is doubtable to the manufacturers. A trial to reduce the fluff trouble by using chemicals to hold the short fiber on the surface of the yam was suggested and the research showed a positive effect to the problem. However, another factors including a by-product of chemical residue and searching more feasible material need to be concerned for the future research.

Comparison of temperature dependance between short and long period fiber gratings (단주기 광섬유 격자(Fiber Grating)와 장주기 광섬유 격자의 온도 의존성 비교)

  • Choi, Bo-Hun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.8
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    • pp.1791-1796
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    • 2011
  • An optical fiber short period grating of 0.7 nm as a 3 dB wavelength linewidth was fabricated using a Gaussian distributed KrF Eximer laser and a phase mask. This grating has temperature dependancy of 0.01 nm/$^{\circ}C$ over the range of -10 $^{\circ}C$ ~ 70 $^{\circ}C$and no difference between temperature directions. An optical fiber long period grating of 14.22 nm as a 3 dB linewidth was also fabricated using a amplitude mask and has dependancy of 0.01 nm/$^{\circ}C$ over the same range.