• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.24 no.5
• /
• pp.499-506
• /
• 2011

In this study, the performance of composite safety barriers was evaluated through computer simulation. A composite safety barrier of SB4 grade was modeled. The MAT58 material model provided by LS-DYNA software was used to model composite material. The performance of composite material varies according to fiber, resin type, and fiber direction. Polyurethane resin and glass fiber were used. The performance of three different stacking designs was evaluated by carrying out vehicle impact simulation. The performance evaluation based on the vehicle crash manual includes the structural strength performance, the passenger protection performance, the vehicle behavior after crash, scattering of the guardrail. As the result of the finite element analysis, the barrier composed of the more transverse direction fibers shows the better performance on the impact simulation.

• Applied Chemistry for Engineering
• /
• v.8 no.3
• /
• pp.416-424
• /
• 1997

Mass transfer mechanism and concentration profiles in the axial direction at each phase were analyzed and simulated by a theoretical modeling on a liquid-liquid static contactor using highly packed fiber bundle. The concentrations at the end of the fiber extractor calculated at several operational conditions were compared with experimental results. The fiber extractor could be completely predicted by a plug flow model without axial dispersion. A parameter used in the model equations, $k_a{\sigma}$ called the product of mass transfer coefficient and mass transfer area per unit length of the fiber extractor in the axial direction, which was determined by a curve-fitting, was confirmed to be a unique characteristic value of the fiber extractor, and was about 0.0327cm2/sec.

• Applied Chemistry for Engineering
• /
• v.27 no.2
• /
• pp.179-184
• /
• 2016

In this work, the influence of milled carbon fiber direction on mechanical properties of milled carbon fibers/carbon blacks/natural rubber compounds was investigated. The compounds were prepared by adding the 6 phr milled carbon fibers (MCFs) and 40 phr carbon blacks (CBs) into the natural rubber. The MCFs were aligned in a parallel and orthogonal direction in the compounds using two-roll-mill machine. Mechanical properties of compounds were studied by tensile characteristics and tearing strength. As a result, the compounds showed higher tensile strength, 100%~300% modulus, and tearing strength than those of using any other compounds due to the aligning MCFs in parallel. Mechanical properties of the compounds reinforced with non-aligned MCFs were inferior to those of others. Consequently, the parallel aligned MCFs in the compounds led to an increase of tensile properties and improvement of tearing strength, resulted from MCFs with the high elastic modulus.

• Proceedings of the Korean Fiber Society Conference
• /
• 2001.10a
• /
• pp.428-431
• /
• 2001

토목합성재료(Geosynthetics) 중 배수용으로 사용되는 재료는 기능상 유체의 흐름을 수평방향으로 유도하는 재료를 의미하며, 일반적으로 저장된 유체를 수직으로 이동시키는 필터기능을 가지는 1,000g/㎡ 미만의 지오텍스타일(geotextiles)과 수평방향의 유도로를 확보한 지오네트(geonets)를 결합시킨 지오네트 복합제품이 사용되고 있다. 이러한 배수용 토목합성재료는 쓰레기 매립장의 건설 시 침출수의 외부유출을 차단하기 위하여 설치하는 차수막인 지오멤브레인(geomembranes)을 매립된 쓰레기 하중 및 외부의 충격으로부터 보호하는 용도로 사용된다. (중략)

• Fiber Technology and Industry
• /
• v.8 no.2
• /
• pp.103-109
• /
• 2004

첨단섬유의 기술개발은 기술개발의 혁신화로 볼 수 있는데, 혁신화 방향은 생산프로세스 혁신화와 신제품 개발 등 2가지로 볼 수 있다. 생산프로세스 혁신화는 성력화, 에너지절감, 고품질화, 다품종화를 목적으로 한 고속화, 연속화, 자동화, 고 효율화 등으로 진행되어 왔다. 또 신제품 개발에 대해서는, 소비자, 사용자의 요구가 점점 다양화, 고도화하는 가운데, 그것에 대응하는 차별화, 고부가가치화제품의 개발과 새로운 고기능, 고성능소재의 개발에 중점을 두고 있다. (중략)

• Journal of the Korea Concrete Institute
• /
• v.26 no.3
• /
• pp.307-313
• /
• 2014

In order to predict the post-cracking tensile behavior of fiber reinforced concrete, it is necessary to evaluate the fiber orientation factor which indicates the number of fibers bridging a crack. For investigation of fiber orientation factor on a circular cross-section, in this paper, cylindrical steel fiber reinforced concrete specimens were casted with the variables of concrete compressive strength, circular cross-section size, fiber type, and fiber volumetric ratio. The specimens were cut perpendicularly to the casting direction so that the fiber orientation factor could be evaluated through counting the number of fibers on the circular cross-section. From the test results, it was investigated that the fiber orientation factor on a circular cross-section was lower than 0.5 generally adopted, as fibers tended to be perpendicular to the casting direction. In addition, it was observed that the fiber orientation factor decreased with an increase of the number of fibers per unit cross-section area. For rational prediction of the fiber orientation factor on a circular section, a rigorous model and a simplified equation were derived through taking account of a possible fiber inclination angle considering the circular boundary surface. From the comparison of the measured data and the predicted values, it was found that the fiber orientation factor was well predicted by the proposed model. The test results and the proposed model can be useful for researches on structural behavior of steel fiber reinforced columns with a circular cross-section.

• Composites Research
• /
• v.24 no.5
• /
• pp.1-8
• /
• 2011

This paper presents the results of theoretical analysis and experimental test to show the size effect on the fiber strength of filament would pressure vessel. First, a series of fully scaled hoop ring tests with filament would carbon-epoxy were conducted, which exhibited a remarkable size effect on the fiber strength. Next, the failure analyses using WWLM(Weibull Weakest Link Model) and the SMFM(Sequential Multi-step Failure Model) were performed and compared to the hoop ring test data, as well as to unidirectional specimens test data from the literature. It was found that the analysis results significantly underestimated the fiber strengths compared to the test data. In this study, a modified SMFM was proposed through the modification of the length size effect. The fiber strengths from modified SMFM analysis showed good agreement with the test data.

• Journal of the Korean Wood Science and Technology
• /
• v.35 no.3
• /
• pp.29-35
• /
• 2007

This research investigates the composites reinforced with fiberglass to wood and commercial particleboard using VARTM process to enhance the mechanical properties. Specimens were prepared from lumbers from thinning crop-trees and commercial particleboard. Matched specimen were reinforced on both sides with one layer of unidirectional fiberglass roving. Fiberglass reinforcement to wood and particleboard using VARTM process improved mechanical properties.

• Computational Structural Engineering
• /
• v.11 no.3
• /
• pp.229-239
• /
• 1998

복합재료는 강도-무게비가 다른 재료들에 비해 훨씬 크기 때문에 부재의 좌굴문제가 대단히 중요하게 취급되며, 본 논문에서는 축방향 압축력을 받는 복합재료로 된 쉘 부재의 좌굴해석이 수행된다. 이 재료는 일반적으로 이방성 재료 특성을 나타내 보이나, 섬유들이 한 방향으로만 배치되어 있는 경우 섬유방향에 연직한 평면에서의 강도나 탄성계수들은 모두 일정한 횡 등방성 재료성질을 가진 것으로 간주할 수 있다. 9 절점 degenerate 쉘 유한요소를 사용한 선형안정해석, LUSAS 범용 프로그램을 이용한 구조해석, 그리고 고전적 쉘 좌굴방정식에 의한 해석들을 수행하였으며, 그 결과들을 서로 비교, 분석하였다. 고려된 등방성 재료나 횡 등방성 재료의 경우 모두, degenerate 유한요소해석으로 계산한 임계하중들은 고전적 이론해에 의한 결과들 보다 낮았으며, LUSAS 결과들과는 거의 같았다. 이는 degenerate 유한요소에 의한 선형안정해석 결과들이 안전측에 듬을 의미하며, 복합재료로 된 쉘 구조물의 좌굴해석에 degenerate 유한요소를 효율적으로 적용할 수 있음을 의미한다.

• Journal of the Korean Wood Science and Technology
• /
• v.12 no.3
• /
• pp.3-8
• /
• 1984

It is shown that Paul and Jones' Rule of Mixtures modified by Smith and Cox's theory can be used for the fiber-reinforced, sulfur-based composites, when the constant for the linear regression equation is given. The computation results, programmed by Hewlett Packard 75C (HP 75C) using math rom pack for the linear regression form, expressed as $E_c=\frac{1}{3}aE_fV_f+bE_mV_m$, turn out to be a=3.27-3.54 b=-2.47~-2.80. This results indicate that the factors such as density of fiber mat and the amount of matrix used have nothing for affecting the numerical value of the constants a and b of the linear regression form. Conclusively this results also show that the Paul and Jones' Rule of Mixtures which has been used for the composites made by randomly-oriented long fiber can also be used for the composites made by short fiber with the same fiber orientation such as wood and lignocellulosic fibers.