• Journal of Construction Engineering and Project Management
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• 제4권2호
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• pp.41-46
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• 2014

RCC consumes large quantities of natural resources like gravel stone and steel, and there is a need to investigate on an innovative material that utilizes limited quantities of natural resources but should have good mechanical strength. This study deals with the experimental investigation of strength evaluation of cementitious composites reinforced with polyolefin fibers from 0% to 2.5% (with interval of 0.5%), namely Polyolefin Fiber Reinforced Cementitious Composites (PL-FRCC) and developing statistical regression models for compressive strength, splitting-tensile strength, flexural strength and impact strength of PL-FRCC. Paired t-tests (for each PL fiber percentage 0 to 2.5%) bring out that there is significant difference in compressive and splitting-tensile strength when curing periods (3, 7, 28 days) are varied. Also, a strong relationship exists between the compressive and flexural strength of PL-FRCC. The proposed mathematical models developed in this study will be helpful to ascertain the mechanical strength of FRCC, especially, when the fiber reinforcing index is varied.

• 한국재료학회지
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• 제20권3호
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• pp.148-154
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• 2010

It is necessary to develop new methods to prevent catastrophic failure of structural material in order to avoid accidents and conserve natural and energy resources. Design of intelligent materials with a self-diagnosing function to prevent fatal fracture of structural materials was achieved by smart composites consisting of carbon fiber tows or carbon powders with a small value of ultimate elongation and glass fiber tows with a large value of ultimate elongation. The changes in electrical resistance of CF-GFRP/GFRP (carbon fiber and glass fiber-reinforced plastics/glass fiber-reinforced plastics) composites increased abruptly with increasing strain, and a tremendous change was seen at the transition point where carbon fiber tows were broken. Therefore, the composites were not to monitor damage from the early stage. On the other hand, the change in electrical resistance of CP-GFRP/GFRP (carbon powder dispersed in glass fiber-reinforced plastics/glass fiber-reinforced plastics) composites increased almost linearly in proportion to strain. CP-GFRP/GFRP composites are superior to CF-GFRP/GFRP composites in terms of their capability to monitor damage by measuring change in electrical resistance from the early stage of damage. However, the former was inferior to the latter as an application because of the difficulties of mass production and high cost. A method based on monitoring damage by measuring changes in the electrical resistance of structural materials is promising for improved reliability of the material.

• Composites Research
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• 제31권6호
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• pp.398-403
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• 2018

최근 플라스틱 폐기물로 인한 환경오염, 미세플라스틱의 생태계 교란 및 인체축적이 큰 문제로 떠오르고 있다. 이를 대체하기 위하여 친환경 수지 및 천연섬유 기반의 복합재료가 개발되어 왔으나 합성섬유 기반의 복합재료에 비하여 기계적 물성이 크게 떨어진다는 단점이 있다. 본 연구에서는 천연섬유인 황마섬유(jute fiber)의 기계적 물성을 향상시키기 위하여 해초로부터 친환경 나노섬유를 추출 후 첨가제로 사용하였다. 핸드 레이업 공정을 이용하여 복합재료를 제조하였으며, 인장, 굽힘, 낙추충격시험을 통하여 나노섬유가 천연섬유 복합재료의 기계적 물성 향상에 효과적임을 확인할 수 있었다.

• 대한기계학회논문집A
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• 제30권7호
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• pp.794-799
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• 2006

In recent years, the use of natural fiber as reinforcement in polymer composites to replace synthetic fiber such as glass fiber is receiving increasing attention. Because of increasing usage according to the high demand, the cost of thermoplastic has increased rapidly over the past decades. We used a thermoplastic polymer(polypropylene) as the matrix and a lignocellulosic material(rice-husk flour) as the reinforcement filler to prepare a particle-reinforced composite to examine the possibility of using lignocellulosic material as reinforcement filler and to determine data of test results for physical, mechanical and morphological properties of the composite according to the reinforcement filler content in respect to thermoplastic polymer, In this study, PLA/PP rice-husk fiber-reinforced thermoplastic composites that made by the hot press molding method according to appropriate manufacturing process was evaluated as mechanical properties.

• 한국해양공학회지
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• 제14권4호
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• pp.49-55
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• 2000

This study has been investigated to apply fiber reinforced composites instead of asbestos as a friction material. the reinforced used was E-glass fiber and binder resin was phenol having good mechanical properties and heat resistance. And it has been also investigated the effect of molding conditions and some additives such and carbon black, alumina and rubber powder in E-glass fiber/phenol resin composite on the friction on the friction and wear characteristics. As a result, it was found that the molding conditions of E-glass fiber/phenol resin composites for friction materials had to be different from those of phenol resin and was found that the wear rate of E-glass fiber/phenol resin composites added alumina powder was higher than of composites added carbon black in the same wear distance. And it was found that friction coefficient of E-glass/phenol resin composites added carbon black was decreased and that of the composites added the powder of natural rubber and ABS rubber were increased compared to the composites.

• Composites Research
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• 제32권1호
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• pp.50-55
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• 2019

본 연구에서는 생체모방 섬유강화 복합재에서 섬유의 나선형 구조의 배열이 복합재의 기계적 물성에 미치는 영향을 연구하였다. 유한요소해석을 이용해 원형의 생체모방 섬유강화 복합재를 구성하였고, 다양한 크기의 압력하중을 복합재 면에 적용시켜 굽힘과 파괴 거동의 결과를 분석하였다. 섬유의 정렬 방향에 따라 파괴 형상이 다르게 나타났고, 복합재에서 섬유의 나선형 구조 배열이 압력하중하에서 복합재의 굽힘 파괴강도를 크게 향상시키는 것으로 나타났다. 이는 섬유가 각 층별로 여러 방향으로 정렬되어 외부하중에 의한 파괴에너지가 여러방향으로 분산되는 것에서 기인한다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.42-45
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• 2005

Interfacial evaluation of various combinations of both Flax and Hemp fibers/polypropylene were performed by using micromechanical test and nondestructive acoustic emission (AE). It can be because interfacial adhesion between the natural fiber surface and matrix plays an important role in controlling the overall mechanical properties of polymer composite materials by transferring the stress from the matrix to the fiber. It is necessary to characterize the interphase and the level of adhesion to understand the performance of the composites properly. Microfailure mechanism of single Flax fiber bundles were investigated using the combination of single fiber tensile test and nondestructive acoustic emission. Microfailure modes of the different natural fiber/polypropylene systems were observed using optical microscope and determined indirectly by AE and their FFT analysis.

• 접착 및 계면
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• 제10권1호
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• pp.23-29
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• 2009

두 종류의 천연섬유, 즉 면섬유와 목분을 이용하여 제조한 폴리프로필렌 - 천연섬유 복합재료의 혼합가공시 유변학적 특성과 열적특성에 미치는 상용화제의 영향을 고찰하였다. 상용화제로는 무수말레인산이 그래프팅된 폴리프로필렌 공중합체를 사용하였다. 천연섬유의 종류에 관계없이 상용화제를 첨가할 때, 전반적으로 상용화제의 함량이 증가함에 따라 토오크 값이 상승함이 확인되었다. 또한, 시차 주사 열량계(DSC)와 X선 회절분석(XRD)을 통해 상용화제의 첨가시 복합재료의 결정화도가 약간 상승함이 확인되었다. 섬유의 종류에 따른 영향은 거의 관찰되지 않았으나, 혼합시 유변학적 물성, DSC 및 XRD 결과에 의하면, 면섬유의 경우가 목분보다는 PP-g-MAH와 더 나은 상호작용을 보이는 것으로 생각된다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.111-115
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• 2005

Recently, natural fibers draw much interests in composite industry due to low cost, light weight, and environment-friendly characteristics compared with glass fibers. In this study, mechanical properties were evaluated for two extreme cases of jute fiber orientations, i.e. the unidirectional yarn composites and the felt fabric composites. Samples of jute fiber composites were fabricated by RTM process using epoxy resin, and tensile, compression, and shear tests were conducted. As can be expected, unidirectional fiber specimens in longitudinal direction showed the highest strength and modulus. Compared with glass/epoxy composites of the similar fabric architecture and fiber volume fraction, the tensile strength and modulus of jute felt/epoxy composites reached only 40% and 50% levels. However, the specific tensile strength and modulus increased to 80% and 90% of the glass/epoxy composites. The main reason for the poor mechanical properties of jute composites is associated with the weak interfacial bonding between fiber and matrix. The effect of surface treatment of jute fibers on the interfacial bonding will be examined in the future work.

• Advanced Composite Materials
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• 제18권3호
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• pp.197-208
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• 2009

Changes occurring in jute and coir fiber composites with 2-8% concentration of a NaOH treatment for 24 h were investigated, respectively, for void content, microscopy images, mechanical properties and water absorption. The jute and coir fibers were vacuum dried before molding composite specimens. Mechanical properties indicated good adhesion between natural fibers and PP. Jute fibers, when alkali-treated with 2% concentration for 24 h, showed best improvement in tensile strength by 40% and modulus by 9%, respectively, while coir fibers, when alkali-treated with 6% concentration for 24 h, showed best improvement in tensile strengths by 62% and modulus by 17%, respectively. With 2% concentration of alkali-treatments, the elongation of jute and coir composites reached 8% and 13.5%, respectively. Moisture absorption for jute and coir composites are 50% and 60% lower than untreated fiber composites, respectively.