• Title, Summary, Keyword: CFRP

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A Study on the CFRP Treatment by ion Assisted Reaction Method to Improve T-peel Strength of CFRP/Aluminum Composites (CFRP/알루미늄 복합재에서 이온도움반응법을 적용한 CFRP의 표면처리가 T-peel 강도에 미치는 영향에 대한 연구)

  • Lee, Gyeong-Yeop;Yang, Jun-Ho;Yun, Chang-Seon;Choe, Nak-Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.3
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    • pp.570-575
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    • 2002
  • It is well-known that the bond strength between CFRP(Carbon Fiber Reinforced Plastic) and aluminum is significantly affected by the surface treatment of the CFRP and the aluminum. This study investigates the surface treatment of CFRP to improve the T-peel strength of CFRP/aluminum composites. The surface of %CFRP([0^0]_{14})$ was treated by the ion assisted reaction method under oxygen environment. T-peel strength tests were performed based on the procedure of ASTM D1876-95. The T-peel strength of surface-treated CFRP/aluminum composites was compared with that of untreated CFRP/aluminum composites. The results showed that the T-peel strength of surface-treated CFRP/aluminum composites was about 5.5 times higher than that of untreated CFRP/aluminum composites. SEM examination showed that the improvement of T-peel strength was attributed to the uniform spread and fracture of epoxy adhesive.

Ultimate Stress of Prestressing CFRP Tendons in PSC Beams Strengthened by External CFRP Prestressing (외부 CFRP 프리스트레싱으로 보강된 PSC 보에서 CFRP 텐던의 극한응력)

  • Park, Sang-Yeol;Kim, Chang-Hoon;Hong, Seong-Yong
    • Journal of the Korea Concrete Institute
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    • v.19 no.6
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    • pp.735-744
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    • 2007
  • This study deals with literature review, developing a predicting equation for the ultimate stress of prestressing (PS) CFRP, and experimental test with the parameters affecting the ultimate stress of prestressing CFRF in prestressed concrete beams strengthened by external prestressing. The ACI (American Concrete Institute) predicting equation for the ultimate stress of unbonded prestressing CFRP is analyzed to develop a new integrated predicting equation. The proposed predicting equation takes rationally the effect of internal PS steel into consideration as a function of prestressing tendon depth to neutral depth ratio. In the experimental study, prestressed concrete beams strengthened using external prestressing CFRP are tested with the test parameters having a large effect on the ultimate stress of prestressing CFRP. The test parameters includes infernal prestressing steel and external prestressing CFRP tendon reinforcement ratios, and span to depth ratio. The test results are analyzed to confirm the rationality and applicability of the proposed equation for predicting the ultimate stress of external prestressing CFRP.

ENERGY ABSORPTION CHARACTERISTICS IN SQUARE OR CIRCULAR SHAPED ALUMINUM/CFRP COMPOUND TUBES UNDER AXIAL COMPRESSION

  • CHA C. S.;LEE K. S.;CHUNG J. O.;MIN H. K.;PYEON S. B.;YANG I. Y.
    • International Journal of Automotive Technology
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    • v.6 no.5
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    • pp.501-506
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    • 2005
  • With the respective collapse characteristics of aluminum and CFRP (Carbon Fiber Reinforced Plastics) tubes in mind, axial collapse tests were performed for aluminum/CFRP compound tubes, which are composed of square or circular shaped aluminum tubes wrapped with CFRP outside. In this study, the collapse modes and the energy absorption characteristics were analyzed for aluminum/CFRP compound tubes which have different fiber orientation angle of CFRP. Fracture modes in the aluminum/CFRP compound tubes were rather stable than those in the CFRP tubes alone, probably due to the ductile nature of the inner aluminum tubes. The absorbed energy per unit volume of the aluminum or the aluminum/CFRP compound tubes was higher than that of CFRP tubes. Meanwhile, the absorbed energy per unit mass, for the light-weight design aspect was higher in the aluminum/CFRP compound tubes than in the aluminum tubes or the CFRP tubes. The energy absorption turned out to be higher in circular tubes than in square tubes. Beside the collapse modes and the energy absorption characteristics were influenced by the orientation angle, and the compound tubes took the most effective energy absorption when the fiber orientation angle of CFRP was 90 degrees.

Crack and Debonding Donitoring of RC Beams Strengthened with CFRP Plates (CFRP 판 보강 RC보의 균열 및 박리 손상 모니터링)

  • Yoon, Jun Ho;Han, Jung Hun;Cho, Doo Yong;Park, Sun Kyu
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.4
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    • pp.185-192
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    • 2011
  • A CFRP (Carbon Fiber-Reinforced Plastic) strengthening method being widely used to increase the load-carrying capacity of structures is very suitable for existing bridge structures. However, not only flexure and shear failures but also debonding failure might be additionally occured in reinforced concrete(RC) beams strengthened with the CFRP plates. The CFRP debonding failure would cause a brittle fracture of the beam. Therefore, health monitoring for the CFRP bonding condition is strongly required. In this study, a feasibility of the impedance-based damage detection method using PZT sensors was investigated through a series of experimental studies for realtime structural health monitoring(SHM) for the CFRP laminated concrete structures.

Effect of Plasma Treatment of Aluminum on the Fracture Toughness of Aluminum/CFRP Composites (알루미늄의 플라즈마 표면처리가 알루미늄/CFRP 복합재의 파괴인성에 미치는 영향)

  • 신명근;이경엽
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.8
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    • pp.153-157
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    • 2003
  • In the present work, the effect of plasma treatment of aluminum on the fracture toughness of CFRP/aluminum composites was investigated. The surface of the aluminum was treated by a DC plasma. The plasma treatment was carried out at volume ratio of acetylene gas to nitrogen gas of 5:5 and the treatment time used was 30 sec. Cracked lap shear specimens of aluminum/CFRP composites were made using secondary bonding procedure. Fracture toughness of aluminum/CFRP composites was determined using the work factor approach. Then, the fracture toughness of plasma-treated aluminum/CFRP composites was compared with that of untreated aluminum/CFRP composites. The results showed that the fracture toughness of plasma-treated aluminum/CFRP composites was about 50 % higher than that of untreated aluminum/CFRP composites.

Energy Absorption Characteristics of Al/CFRP Compound Tubes Under Axial Compression (축 하중을 받는 AI/CFRP 혼성튜브의 에너지흡수 특성)

  • 이길성;차천석;문지현;양인영
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.108-113
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    • 2004
  • The compressive axial collapse tests were performed to investigate energy absorption characteristics of Al/CFRP compound tubes which are aluminum tubes wrapped with CFRP (Carbon Fiber Reinforced Plastics) outside the aluminum circular and square tubes. Based on collapse characteristics of aluminum tubes and CFRP tubes respectively, the axial collapse tests were performed for Al/CFRP compound tubes which have different fiber orientation angles. Test results showed that Al/CFRP compound tubes supplemented the unstable brittle failure of CFRP tubes due to ductile nature of inner aluminum tubes. In the light-weight aspect, specific energy absorption were the highest for Al/CFRP, CFRP in the middle, and aluminum the lowest. Also, specific energy absorption of circular tubes was higher than square tubes'. It turned out that fiber orientation angle of Al/CFRP compound tubes influence specific energy absorption together with the collapse modes of the tubes.

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Flexural Behavior of RC Beams Strengthened with CFRP Strips (탄소섬유판으로 보강된 RC보의 휨 거동)

  • Choi, Ki-Sun;You, Young-Chan;Park, Young-Hwan;Park, Jong-Sup;Kim, Keung-Hwan
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.287-290
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    • 2005
  • CFRP strips manufactured in factory are produced normally with smaller width and larger thickness than CFRP sheets. By this reason, bonding force between CFRP strips and concrete substrate is not sufficient to sustain tensile force in CFRP strips. Therefore premature debonding failure cannot be avoided when strengthening is done by simply bonding the CFRP strips. The flexural strength of RC beam strengthened with CFRP strips must be calculated based on the effective strain considering debonding failure. This paper presents test results of an experimental study conducted to evaluate the flexural strength on RC beams strengthened with CFRP strips. 7 specimens were tested with respect to bond length and amount of CFRP strips. From the test results, it was indicated that the strain of the CFRP strips achieved at debonding failure can be decreased less than 6,000$\mu$ depending on the amount of CFRP strips.

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Mechanical properties of ABS resin reinforced with recycled CFRP

  • Ogi, Keiji;Nishikawa, Takashi;Okano, Yasutaka;Taketa, Ichiro
    • Advanced Composite Materials
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    • v.16 no.2
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    • pp.181-194
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    • 2007
  • This paper presents the mechanical properties of a composite consisting of acrylonitrile-butadiene-styrene (ABS) resin mixed with carbon fiber reinforced plastics (CFRP) pieces (CFRP/ABS). CFRP pieces made by crushing CFRP wastes were utilized in this material. Nine kinds of CFRP/ABS compounds with different weight fraction and size of CFRP pieces were prepared. Firstly, tensile and flexural tests were performed for the specimens with various CFRP content. Next, fracture surfaces of the specimens were microscopically observed to investigate fracture behavior and fiber/resin interface. Finally, the tensile modulus and strength were discussed based on the macromechanical model. It is found that the elastic modulus increases linearly with increasing CFRP content while the strength changes nonlinearly. Microscopic observation revealed that most carbon fibers are separated individually and dispersed homogeneously in ABS resin. Epoxy resin particles originally from CFRP are dispersed in ABS resin and seem to be in good contact with surrounding resin. The modulus and strength can be expressed using a macromechanical model taking account of fiber orientation, length and interfacial bonding in short fiber composites.

Anchorage efficiency of mold-type anchorage for CFRP plates (CFRP판 긴장재를 위한 부착형 정착장치의 정착성능)

  • Park, Jong-Sup;Park, Young-Hwan;Jung, Woo-Tai
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.169-172
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    • 2008
  • Carbon fiber reinforced polymer (CFRP) laminates can be used more efficiently in strengthening applications by applying prestress to the CFRP laminates. A key problem for prestressing with CFRP laminates is anchoring the laminates. These may include fracture to the CFRP laminates due to excessive gripping force or slippage of the CFRP laminates out of the anchorage zone caused by low friction between the anchor device and the lamiantes. The main objective of this study is the development of an applicative mold-type anchorage system for prestressed CFRP laminates through experimental study. The experimental parameters were the type of anchorage detail and the effect of surface treatment. The test results showed that the developed anchor assures 100% CFRP laminate strength.

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Axial Collapse Characteristics of Aluminum CFRP Compound Square Members for Vehicle Structural Members (차체구조부재용 알루미늄 CFRP 혼성사각부재의 축 압궤 특성)

  • Lee, Kil-Sung;Cha, Cheon-Seok;Pyeon, Seok-Beom;Yang, In-Young;Sim, Jae-Ki
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.10
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    • pp.1329-1335
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    • 2005
  • An aluminum or CFRP (Carbon Fiber ReinfDrced Plastics)is representative one of light-weight materials but its axial collapse mechanism is different from each other. The aluminum member absorbs energy by stable plastic deformation, while the CFRP member absorbs energy by unstable brittle failure with higher specific strength and stiffness than those in the aluminum member. In an attempt to achieve a synergy effect by combining the two members, aluminum CFRP compound square members were manufactured, which are composed of aluminum members wrapped with CFRP outside aluminum square members with different fiber orientation angle and thickness of CFRP, and axial collapse tests were performed fur the members. The axial collapse characteristics of the compound members were analyzed and compared with those of the respective aluminum members and CFRP members. Test results showed that the collapse of the aluminum CFRP compound member complemented unstable brittle failure of the CFRP member due to ductile characteristics of the inner aluminum member. The collapse modes were categorized into four modes under the iuluence of the fiber orientation angle and thickness of CFRP. The absorbed energy Per unit mass, which is in the light-weight aspect was higher in the aluminum CFRP compound member than that in the aluminum member and the CFRP member alone.