• Title/Summary/Keyword: 섬유배향각

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Fiber Bridging Model Considering Probability Density Function of Fiber Inclined Angle in Engineered Cementitious Composites (보강 섬유의 배향각에 대한 확률밀도함수를 고려한 ECC내의 섬유 가교 모델)

  • Kang, Cheol-Ho;Lee, Bang-Yeun;Park, Seung-Bum;Kim, Yun-Yong
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.6
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    • pp.587-596
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    • 2009
  • The fiber bridging model is the crucial factor to predict or analyze the tensile behavior of fiber reinforced cementitious composites. This paper presents the fiber bridging constitutive law considering the distribution of fiber inclined angle and the number of fibers in engineered cementitious composites. The distribution of fiber inclined angle and the number of fibers are measured and analyzed by the image processing technique. The fiber distribution are considerably different from those obtained by assuming two- or three-dimensional random distributions for the fiber inclined angle. The simulation of the uniaxial tension behavior was performed considering the distribution of fiber inclined angle and number of fibers measured by the sectional image analysis. The simulation results exhibit multiple cracking and strain hardening behavior that correspond well with test results.

Accuracy of Intersection Counting Method in Measurement of Fiber Orientation Angle Distribution Using Image Processing (화상처리에 의한 섬유배향각 분포측정에 있어서 교차점합산법의 정밀도)

  • 이상동;박준식;이동기;한길영;김이곤
    • Journal of the Korean Society for Precision Engineering
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    • v.15 no.12
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    • pp.97-105
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    • 1998
  • The fiber oriented condition inside fiber reinforced composite material is a basic factor of mechanical properties of composite materials. It is very important to meausure the fiber orientation angle for the determination of molding conditions, mechanical characteristics, and the design of composite materials. In the work, the fiber orientation distribution of simulation figure plotted by PC is measured using image processing in order to examine the accuracy of intersection counting method. The fiber orientation function measured by intersection counting method using image processing is compared with the calculated fiber orientation function. The results show that the measured value of fiber orientation function using intersection counting method is lower than the calculated value, because the number of intersection between the scanning line and the fiber with smaller fiber aspect ratio is counted less than with larger fiber aspect ratio.

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항공기용 하이브리드 복합재료의 섬유배향각에 따른 피로균열전파와 층간분리 거동

  • 김태수;송삼홍;김철웅
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.76-76
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    • 2004
  • 하이브리드 복합재료 중에서 적충형태의 Al/GFRP는 단일재 알루미늄에 비해 피로특성, 비강도, 비강성 등이 매우 우수하여 Fig. 1과 같이 항공기 주익 구조에 주로 적용된다. 그러나 이러한 Al/GFRP 적층재 역시 장시간에 걸쳐 비행하중을 받게 되면 다양한 형태의 파손이 발생할 수 있다. 이 중 알루미늄층과 섬유층 사이에서 발생하는 층간분리는 Al/GFRP 적층재의 대표적인 피로파손 형태이며, 현재 이러한 파손은 다 방면으로 연구되고 있다.(중략)

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The comparison of the tensile strength of fiber-reinforced composites according to the change of fiber orientat and fiber orientation angle in one direction (섬유배향과 일방향 섬유배향각 변화에 다른 복합재료의 인장강도 비교)

  • Kim Jin-Woo;Lee Jung-Ju;Lee Dong-Gi
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.284-287
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    • 2004
  • After we experiment one direction fiber reinforced composites$(\theta\;=\;0^{\circ},\;J=1)$ to the X direction$(\theta\;=\;0^{\circ},\;J=1)$, we can say that fiber orientation efficiency and fiber orientation angle efficiency become lower. It is because the more the fabric is orientated in a equal direction with one direction fiber floor the more the load given from the exterior becomes shear rather than tension, even though one direction fiber floor gets the most of the exterior power. when fiber content ration is $10wt\%$, the fiber reinforcement efficiency of J=0.3 is similar with the fiber reinforcement efficiency of $\theta=30^{\circ}$ We also found that the fiber reinforcement efficiency of J=0.2 is similar with the fiber reinforcement efficiency of $\theta=20^{\circ}$ in case of $20wt\%$.

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Measurement of Fiber Orientation-Angle Distribution of Glass Fiber Reinforced Polymeric Composite Materials by Intensity Method (농도법에 의한 GFRP 복합재료의 섬유배향각 분포측정)

  • Kim, H.;Ann, J.Y.;Lee, D.G.;Han, G.Y.;Kim, E.G.
    • Journal of the Korean Society for Precision Engineering
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    • v.13 no.6
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    • pp.34-44
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    • 1996
  • In order to examine the accuracy of the intensity method, the fiber orientation-angle distribution of fiber-reinforced polymeric composites is measured using image processing. The fiber orientation function is calculated from the fiber orientation measured by the soft X-ray photograph. Theoretical and experimental results of fiber orientation function are compared for the composites with different fiber contents and fiber orientations. The intensity method is used for the experimental investigation and the measured fiber orientation function is compared to the calculated one. The relations between the measured and the simulated fiber orientation functions $J{\small{M}}$ and $J{\small{S}}$ respectively are identified. For the fiber length of 1.000mm and 2.000mm, it shows that $J{\small{M}}=0.83J{\small{M}}$. However. in general. the value of $J{\small{M}}$ decreases as the fiber length increases. For GFRP composites the relations between $J{\small{M}}$ and theoretical value J show that $J{\small{M}}$=0.73J for short fiber and $J{\small{M}}$=0.81J for long fiber.

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A Study on the Buckling and Postbuckling Behaviors of Laminated Composite Plates and Stiffened Laminated Composite Panels by Finite Element Method (유한요소법을 이용한 복합적층판과 보강된 복합적층 패널의 좌굴 및 좌굴후 거동에 관한 연구)

  • 허성필;양원호;성기득;조명래
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.12 no.4
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    • pp.599-606
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    • 1999
  • 복합 적층 판과 보강 재를 설치한 보강된 복합 적층 패널의 좌굴을 고려한 설계에서, 좌굴이 항상 구조물의 최종 파손을 의미하는 것은 아니므로 이들의 좌굴 및 좌굴 후 거동에 대한 정확한 이해와 연구가 필요하다. 본 연구에서는 유한요소 법을 이용하여 적층 메커니즘과 섬유 배향각, 적층 순서 등이 복합 적층 판과 보강된 복합 적층 패널의 좌굴 및 좌굴 후 거동에 미치는 영향을 체계적으로 해석하였고, 각 변수에 따른 좌굴 및 좌굴 후 거동 특성을 분석하였다.

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Effects of Aspect and Area Ratio of Fiber on the Accuracy of Intensity Method in Measurement of Fiber Orientation-Angle Distribution (섬유배향각 분포측정에 있어서 농도법의 정밀도에 미치는 섬유종횡비와 면적비의 영향)

  • Lee, S.D.;Kim, H.;Lee, D.G.;Han, G.Y.;Kim, E.G.
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.4
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    • pp.953-959
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    • 1998
  • To investigate accuracy of intensity method for measurement of the fiber orientation distribution, fiber orientation function is calculated by drawing simulation figures for the fiber orientation as varying fiber aspect ratio, fiber area ratio, and fiber orientation state, respectively. The values of fiber orientation function measured by intensity method are compared with the calculated values of fiber orientation function. The results show that measurement accuracy of the fiber orientation angle distribution by intensity method is affected by the fiber aspect ratio when the total length of oriented fiber is same. The average gradient of fiber orientation function is 0.94 for 1000mm of the total fiber length and is 0.93 for 2000 mm when the fiber aspect ratio is over 50. Measurement accuracy by intensity method is about 94% and the reliable data can be obtained by intensity method.

Engineering Property of Basalt Fiber as a Reinforcing Fiber (보강 섬유로서 현무암 섬유의 공학적 특성)

  • Choi, Jeong-Il;Jang, Yu-Hyun;Lee, Jae-Won;Lee, Bang-Yeon
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.3 no.1
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    • pp.84-89
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    • 2015
  • Basalt fiber has many advantages as a reinforcing fiber such as high tensile strength and similar density to concrete. This study investigated the bonding property and the effect of fiber orientation on tensile strength of basalt fiber. Single fiber pullout tests for basalt and polyvinyl alcohol (PVA) fibers were performed to evaluate the bonding property between basalt fiber and mortar. And then tensile strength of basalt, PVA, and polyethylene (PE) fibers according to fiber orientation were measured. From the test results, it was exhibited that the chemical bond, frictional bond, and slip-hardening coefficient of basalt fiber were 1.88, 1.03, 0.24 times of PVA fibers, respectively. And the strength reduction coefficient of basalt fiber was 9 times of PVA fiber and 3 times of PE fiber.

An Evaluation on Bending Behaviors of Conical Composite Tubes for Bicycle Frames (자전거 프레임용 원추형 복합재 튜브의 굽힘 거동 분석)

  • Hwang, Sang-Kyun;Lee, Jung-Woo;Hwang, Hui-Yun
    • Composites Research
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    • v.29 no.6
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    • pp.358-362
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    • 2016
  • Mechanical properties of static and dynamic behavior became important since the use of conical composite tubes in large structures such as aerospace, planes, and submarines as well as leisure goods such as bicycle frames, fishing rods, and golf shafts. In the past, the mechanical property prediction model for static behavior was studied using vibration, bending, and buckling. But there is a need to study how fiber orientation error affects mechanical properties of conical composite structure because the model assumes constant fiber orientation angle. The purpose of this study is to derive an equation that can predict the static behavior of conical composite tube for bicycle frames by considering fiber orientation error with respect to various design parameters.