• Title/Summary/Keyword: Fiber Reinforced Plastics

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Damage Monitoring of CP-GFRP/GFRP Composites by Measuring Electrical Resistance

  • Shin, Soon-Gi;Kwon, Yong-Jung
    • Korean Journal of Materials Research
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    • v.20 no.3
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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.

A study on the orthogonal cutting characteristics of glass fiber reinforced plastics (복합재료의 직교 절삭가공 특성에 관한 연구)

  • 송화용;정용운;김준현;김주현
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2001.10a
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    • pp.155-160
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    • 2001
  • In the use of glass fiber reinforced plastics(GFRP) it is often necessary to cut the components, but the cutting of GFRP is often made difficult by the delamination of the compositions and short tool life. Experimental investigation was conducted to evaluate the chip formation of the glass fiber reinforced plastics during orthogonal cutting. The chip formation process, cutting force, and thrust force were studied. The chip formation processes were studied through the use of quick-stop device. Chip-tool contact areas were obtained with the use of the quick-stop device, and observed using optical microscopy after polishing. Cutting force and thrust force were measured through the use of the tool dynamometer.

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A study on the machinability of Carbon Fiber Reinforced Plastics on tool shape (공구형상에 따른 CFRP(Carbon Fiber Reinforced Plastics) 복합재료의 절삭 특성에 관한 연구)

  • Shin, Bong-Cheul;Kim, Kyu-Bok;Ha, Seok-Jae;Cho, Myeong-W
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.20 no.6
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    • pp.799-804
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    • 2011
  • CFRP(Carbon Fiber Reinforced Plastics) has been used many industries aerospace, automobile, medical device and building material industries, etc. Because it is lighter than other metals and has good properties, such as rigidity, strength and wear. CFRP may be cured integrity. However, it needs postprocessing similar to drilling or endmilling for shape cutting and combination of various material. In this paper, tool dynamometer and accelerometer used to signal analysis for machining properties under various cutting conditions and tool shape changes. In addition, microscope used to verify the machined CFRP surface. As the results, it was found that the cutting force and the vibration were decreased in the increasing of cutting edge (2-flute < 4-flute < composite tool), and the good machined surface can be obtained in this experiments.

Flexural Behavior of Reinforced Concrete Beams Strengthened with Grid-typs Carbon Fiber Plastics (탄소격자섬유로 보강한 철근 콘크리트보의 휨파괴 특성에 관한 연구)

  • 태기호
    • Journal of Ocean Engineering and Technology
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    • v.14 no.1
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    • pp.52-59
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    • 2000
  • Flexural fracture characteristics of newly-developed Grid-type carbon fiber plastics in the deteriorated reinforced concrete structures were investigated by the four-points fracture test to verify the strengthening effects in the beam specimens. Results showed that initial cracks appeared in the boundary layers of fibers embedded in the newly-placed mortar concrete slowly progressed to the direction of supports and showed fracture of fiber plastics and brittle failure of concrete in compression in sequence after the yielding of steel reinforcement. Accordingly the reasonable area of Grid-type carbon-fiber plastics in the strengthening design of deteriorated RC structures should be limited and given based on the ultimate strength design method to avoid the brittle failure of concrete structures.

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The effects of reinforcements on the tool wear during cutting fiber-reinforced plastics (섬유강화 복합재료의 가공시 강화재가 공구마모에 미치는 영향)

  • 정용운;김주현;박주승;좌성훈
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 1999.11a
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    • pp.208-212
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    • 1999
  • In the use of glass fiber reinforced plastics(GFRP), cutting is often necessary. But the most of past studies have been interested in the effect of fiber orientation on tool wear. In this study, the effects of fiber contents on tool wear were investigated experimentally. By proper selection of cutting tool, the variables are cutting speed and fiber contents of 10, 20, 30wt% with fixed feed rate and depth of cut.

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Surface Characteristics with respect to Magnetic Abrasive Finishing in Carbon Fiber Reinforced Plastics (탄소섬유강화 복합재료의 자기연마 가공에 대한 표면특성)

  • Mun, Sang-Don;Song, Jun-Hee
    • Korean Journal of Metals and Materials
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    • v.49 no.7
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    • pp.522-529
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    • 2011
  • Carbon fiber reinforced plastics (CFRP), which have been developed for their high mechanical properties, are insufficient to secure machinery. This paper investigates the use of magnetic abrasive finishing methods and the characteristics of surface roughness for mirror machining of CFRP. The cylindrical surface of CFRP was ground using a diamond paste with sizes of 0.1, 0.5, 1 and 6${\mu}m$. Consequently, an effective surface roughness of 0.03${\mu}m(R_a)$ could be obtained via a paste size of 0.5${\mu}m$. The surface roughness was not improved due to epoxy abrasion between the carbon fiber and the epoxy.

Tribological Characteristics of Carbon Fiber Reinforced Plastics by Surface modification (탄소섬유복합재의 표면개질에 따른 트라이볼로지 특성에 관한 연구)

  • 전승흥;양준호;오성모;이봉구
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2000.11a
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    • pp.29-36
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    • 2000
  • This investigation has been studied about friction and wear properties which were important problem, when carbon fiber reinforced plastic(CFRP) was used practically. Unidirection carbon fiber reinforced composites was fabricated with epoxy resin matrix and carbon fiber as a reinforced, and its surface was modified by the ion-assisted reaction. And then we tested the their friction and wear properties according to the ion-irradiation. when the amount of ion-irradiation was 1${\times}$10l6$\^$16/ ions/$\textrm{cm}^2$, the friction coefficient values were about 0.1, where as, the friction coefficient values of non-treatment composites were about 0.16. The former was the stablest in wear mode. We know that ion-irradiation was not proportioned to the friction coefficient, so we found the optimal conditions of the friction and wear according to the ion-irradiation.

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A Comparative Study on the Shear-Strengthening Effect of RC Beams Strengthened by FRP (FRP로 보강된 RC보의 전단보강효과 비교연구)

  • 심종성;김규선
    • Magazine of the Korea Concrete Institute
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    • v.10 no.4
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    • pp.101-111
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    • 1998
  • This study presents test results of RC beams strengthened by carbon fiber sheet(CFS), carbon fiber reinforced plastics(CFRP) or glass fiber reinforced plastics(GFRP) for increasing shear resistance. Nineteen specimens were tested, and the test was performed with different parameters including the type of strengthening materials(CFS, GFRP, CFRP), shear-strengthening methods(wing type, jacket type, strip type), strip-spacing, strengthening direction of FRP. The test results show that shear-damaged RC beams strengthened by FRP(CFS, GFRP, CFRP) have more improved the shear capacity. The mathematical model based on plastic theory was also developed to predict shear strength of shear-damaged RC beams strengthened by FRP. The predictions using the mathematical model. are agreed with the observations from the observed shear strengths for 19 test beams.

Reinforced concrete corbels strengthened with carbon fiber reinforced plastics

  • Lu, Wen-Yao;Yu, Hsin-Wan;Chen, Chun-Liang;Yang, Tzong-Hwan;Lin, Yu-Sin
    • Computers and Concrete
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    • v.10 no.3
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    • pp.259-276
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    • 2012
  • A total of nine reinforced concrete corbels were tested, in this study. Six were externally strengthened with carbon fiber reinforced plastics (CFRP), in the horizontal direction. The cross-sectional area of CFRP and the shear span-to-effective depth ratios are the parameters considered, in this study. Test results indicate that the higher the cross-sectional area of CFRP, the higher is the shear strength of the corbels, and the lower the shear span-to-effective depth ratios, the higher is the shear strength of corbels. The shear strength predicted by the design provisions in section 11.8 of the ACI Code, the strut-and-tie model in Appendix A of the ACI Code, and the softened strut-and-tie (SST) model were compared with the test results. The comparisons show that both the strut-and-tie model in Appendix A of the ACI Code, and the SST model can accurately predict the shear strength of reinforced concrete corbels, strengthened with CFRP.