• Journal of the Korean Society for Aviation and Aeronautics
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• v.17 no.4
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• pp.42-47
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• 2009

Recently, the wide range of the composite materials is used for the making airplanes, trains and automobiles body for the lightweight. Despite having complex structures, composite materials usually have well defined mechanical characteristics. However, composite materials are difficult to understand the fracture mechanism clearly by simple mechanical test. Nondestructive evaluation (NDE) combined with mechanical testing can play a more important role and especially Acoustic Emission Testing (AET) would become known to be a useful tool to assess damage and fracture behavior of composites. In this study The experiment was performed to acquire the acoustic emission signal during tensile test using unidirectional CFRP specimen and the data was analyzed the acoustic emission parameters with the waveform.

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.515-521
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• 2023

In this study, waste carbon fiber obtained by pyrolysis of carbon fiber reinforced plastic (CFRP) was used to produce carbon fluoride through vapor phase fluorination and recycled as a reducing electrode material for lithium primary batteries. First, the physicochemical properties of the waste carbon fiber obtained by pyrolysis were determined, and the structural and chemical properties of carbon fluoride were analyzed to evaluate the effect of vapor phase fluorination on the waste carbon fiber. XRD analysis confirmed that the hexagonal network carbon laminated structure (002 peak) of the waste carbon fiber was gradually converted into a carbon fluoride structure (CF_X, 001 peak) as the temperature of gas phase fluorination increased. The discharge capacity of the lithium primary battery produced using this carbon fluoride was up to 862 mAh/g. This was compared to the discharge capacity of carbon fluoride-based Li-ion batteries made of other carbon materials. These results suggest that carbon fluoride made from waste CFRP-based carbon fibers can be used as a reducing electrode material for Li-ion batteries.

• Composites Research
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• v.28 no.1
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• pp.15-21
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• 2015

The purpose of this paper is to investigate the current trends of composite applications in the marine and leisure fields and to study the development of 33ft class America's cup training CFRP sailing yacht. In the field of marine and leisure, composite materials have been just used to marine and leisure structures, recently. Especially, since the America's cup of sailing yacht racing has required the light weight and high mechanical performance to make a high speed, CFRP have been recognized as the critical material to construct the racing yacht structures. To establish the process of CFRP racing yacht construction, the design optimizations and production methods of carbon mast and CFRP yacht hull were discussed in this paper. Finally, the constructed CFRP sailing yacht exhibited high performance as the racing yacht through the sailing test.

• Composites Research
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• v.23 no.6
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• pp.1-6
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• 2010

The electrical conductivity of carbon-fiber reinforced plastics (CFRP's) has been improved by indium-tin oxide (ITO) nano-particle coating on carbon fibers for the purpose of lightning strike protection of composite fuselage skins. ITO nano-particles were coated on the surface of carbon fibers by spraying the colloidal suspension with 10~40% ITO content. The electrical conductivity of the CFRP has been increased more than three times after ITO coating, comparable to or higher than that of B-787 composite fuselage skins with metal wire-meshes on the outer surface, without sacrificing the tensile property due to the existence of nano-particles at fiber-matrix interface. The damage area by the simulated lightning strike was also verified for different materials and conditions by using ultrasonic C-scan image. As the electrical conductivity of 40% nano-ITO coated sample surpass that of the B-787 sample, the damage area by lightning strike also appeared comparable to that of the materials currently employed for composite fuselage construction.

• Applied Chemistry for Engineering
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• v.32 no.4
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• pp.361-370
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• 2021

Carbon fiber reinforced polymer (CFRP) is one of the composite materials, which has a unique property that is lightweight but strong. The CFRPs are widely used in various industries where their unique characteristics are required. In particular, electric and unmanned aerial vehicles critically need lightweight parts and bodies with sufficient mechanical strengths. Vehicles using the battery as a power source should simultaneously meet two requirements that the battery has to be safely protected. The vehicle should be light of increasing the mileage. The CFRP has considered as the one that satisfies the requirements and is widely used as battery housing and other vehicle parts. On the other hand, in the battery area, carbon fibers are intensively tested as battery components such as electrodes and/or current collectors. Furthermore, using carbon fibers as both structure reinforcements and battery components to build a structural battery is intensively investigated in Sweden and the USA. This mini-review encompasses recent research trends that cover the classification of structural batteries in terms of functionality of carbon fibers and issues and efforts in the battery and discusses the prospect of structural batteries.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.7
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• pp.1165-1171
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• 2004

The free vibration analyses of the isotropic and CFRP laminated composite rectangular plates with point supports at the fix edge is performed by FEM. We showed optimal position and mode shape of point supports that maximized fundamental natural frequency of the isotropic and CFRP laminated composite rectangular plates by each aspect ratio and the number of point supports.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1990.10a
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• pp.137-142
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• 1990

본 연구에서는 유한요소법을 사용하여 이방성으로 적층된 평판의 고유모드 를 예측하고, 이론적인 예측의 정확성을 연구하기 위해 사변 단순지지의 다 양한 각도로 적층된 정사각형 CFRP평판의 8번째 진동모드까지 실험적인 결 과와 비교하였다. 이 연구에서 사용된 모든 평판은 중앙면에 대칭이며, 이것 은 Bundling-stretching coupling을 제거하기 위해서이다. 그러나 만일 비대 칭적으로 적층된 평판이라면 이 효과를 포함한 해석이 되어야 할 것이다.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.2
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• pp.115-123
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• 2007

For investigating self-diagnosis applicability, a method based on monitoring the changes in the electrical resistance of carbon fiber reinforced concrete has been tested. Then after examining change in the value of electrical resistance at each flexural weight-stage of carbon fiber in CFGFRP (carbon fiber and glass fiber reinforcing plastic) with new type rib and carbon sheet for concrete reinforcing, the correlations of electrical resistance and load as a function of strain, deflection were analyzed. As the results, it is clarified that when carbon fiber rod, rib and sheet fracture, the electrical resistance of it increase largely, and specially in case of CFGFRP, afterwards glass fiber tows can be resist the load due to the presence of the hybrid (carbon and glass) reinforced fiber. Therefore, it can be recognized that reinforcing bar and new type rib of CFGFRP and sheet of CF could be applied for self-diagnosis of fracture in reinforced FRP concrete.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.4
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• pp.419-425
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• 2014

This study applied finite element analysis (FEA) to the body frame of the 200-meter class multi-legged subsea walking robot known as Crabster (CR200). The body frame of the CR200 is modeled after the ribcage of a human so that it can disperse applied external loads. It is made of carbon-fiber-reinforced plastic (CFRP). Therefore, the frame is lighter and stronger than it would be if it were made of other conventional materials. In order to perform FEA for the CFRP body frame, we applied the material properties of the CFRP as obtained from a specimen test to an FE model of CFRP frame. Finally, we performed FEA with respect to the load conditions encountered when the robot is launched into and recovered from the sea. Also, we performed FEA for the frame, assuming that it was fabricated using a conventional material, in order to compare its characteristics with CFRP.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.3
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• pp.589-596
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• 2018

Transportation or structure has the important role at clothing, food, and housing at modern society. If even the small crack happens and propagates at transportation or structure, the parts are fractured and they can cause a disaster. CT specimen was used in order to investigate the damage trend due to the crack propagation at this study to prevent this situation. As the material of CT specimen, the unidirectional carbon fiber reinforced plastic of the composite material in the limelight nowadays. The laminate angle designated in order of [60/-60/60/-60] was applied to the specimen model with the unidirectional fiber. As the analysis condition, the forced displacement was applied to the hole of upper part after fixing the hole of lower part. At the result of this study, the equivalent stress and shear stress was shown to be higher in order of the structural steel, copper, titanium and aluminum. This study result is thought to be utilized usefully at verifying the damage of CT specimen made of inhomogeneous material.