• Composites Research
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• 제35권6호
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• pp.402-411
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• 2022

In this study, the channels-contained hybrid membranes have been fabricated through the incorporation of glass fibers and GO sheets (GO/glass fibers, GG), or a mixture of chitosan/GO (CS/GO/glass fibers, CGG), as hybrid membranes using in organic dye removal. The material properties are well investigated the terms in the morphological, chemical, crystal, and thermal characterizations for verifying interactions in their formed structure. These hybrid membranes have been fitted well in pseudo-second order and Langmuir models that are associated with chemical adsorption and a monolayer approach, respectively. The highest adsorption ability of methylene blue and methyl orange reached 59.40 mg/g and 229.07 mg/g (GG); and 287.47 mg/g and 252.91 mg/g (CGG), which is more enhanced than that of previous GO-based other adsorbents. Moreover, the dye separation on these membranes could be favorable to superb sealing and trapping dye molecules from water instead of only the dye connection occurring on their surface, regarding the physically sieving effect. The membranes can also be reused within two and three adsorbing-desorbing cycles on the GG and CGG ones, respectively. These membranes can become future adsorbents to be applied for wastewater treatment due to their structural features.

• Korean Membrane Journal
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• 제1권1호
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• pp.1-7
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• 1999

Pd-ceramic composite membranes and catalytic membrane reactors(CMR) have been studied for hydrogen and its isotopes (deuterium and tritium) purification and recovery in the fusion reactor fuel cycle. Particularly a closed-loop process has been studied for recovering tritium from tritiated water by means of a CMR in which the water gas shift reaction takes place. The development of the techniques for coating micro-porous ceramic tubes with Pd and Pd/Ag thin layers is described : P composite membranes have been produced by electroless deposition (Pd/Ag film of 10-20 $\mu$m) and rolling of thin metal sheets (Pd and Pd/Ag membranes of 50-70 $\mu$m). Experimental results of the electroless membranes have shown a not complete hydrogen selectivity because of the presence of some defects(micro-holes) in the metallic thin layer. Conversely the rolled thin Pd and Pd/ag membranes have separated hydrogen from the other gases with a complete selectivity giving rise to a slightly larger (about a factor 1.7) mass transfer resistance with respect to the electroless membranes. Experimental tests have confirmed the good performances of the rolled membranes in terms of chemical stability over several weeks of operation. Therefore these rolled membranes and CMR are adequate for applications in the fusion reactor fuel cycle as well as in the industrial processes where high pure hydrogen is required (i.e. hydrocarbon reforming for fuel cell)

• Advances in nano research
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• 제15권2호
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• pp.175-189
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• 2023

The under-evaluation structure includes a functionally graded porous (FGP) core which is confined by two piezoelectric carbon nanotubes reinforced composite (CNTRC) layers. The whole structure rests on the Pasternak foundation. Using quasi-3D hyperbolic shear deformation theory, governing equations of a sandwich plate are driven. Moreover, face sheets are subjected to the electric field and the whole model is under thermal loading. The properties of all layers alter continuously along with thickness direction due to the CNTs and pores distributions. By conducting the current study, the results emerged in detail to assess the effects of different parameters on buckling of structure. As instance, it is revealed that highest and lowest critical buckling load and consequently stiffness, is due to the V-A and A-V CNTs dispersion type, respectively. Furthermore, it is revealed that by porosity coefficient enhancement, critical buckling load and consequently, stiffness reduces dramatically. Current paper results can be used in various high-tech industries as aerospace factories.

• Composites Research
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• 제22권2호
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• pp.24-29
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• 2009

본 연구에서는 알루미늄 허니컴 코어와 카본 면재가 적용된 샌드위치 복합재 구조에 대해 준정적 압입 손상 이후의 잔류 강도 평가에 대한 연구를 수행하였다. 3점 굽힘 시험과 압축 시험을 통해 시편의 강도를 확인하고 시편에 손상을 모사하기 위하여 준정적 압입 손상을 가하였다. 손상된 시편을 손상 전 시편과 동일한 시험을 통해 손상 전의 강도와 비교하였다. 압입 손상 이후 압축 강도와 굽힘 강도는 압입 깊이의 증가에 따라 강도가 감소하였고 손상 단계에 따른 잔류 강도 정도를 확인하였다.

• Advances in nano research
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• 제16권1호
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• pp.81-90
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• 2024

In the oil and gas industry, composite materials should exhibit high flexibility and strength for offshore structures. Therefore, weak points in the composites should be improved, such as brittleness, moisture penetration, and diffusion of detrimental ions into nanometric pores. This study aimed to increase the strength, flexibility, and plugging of nanopores using single-layer graphene oxide (SGO) nanosheets. Therefore, SGO is added to unsaturated polyester resin at concentrations of 0.015 and 0.15 % with Normal Methyl Pyrrolidone (NMP) as a solvent for the formation of Nanographene Oxide Reinforced Polymer (NGORP). The mechanical properties of the prepared samples were tested using tensile testing (ASTM-D 638). It has been shown that incorporating SGO, approximately 0.015%, into the base resin resulted in enhanced properties such as rupture resistance forces increased by 745.61 N, applied stress tolerances increased by 4.1 MPa, longitude increased to 1.58 mm, elongation increased by about 2.38%, and rupture energy increased by about 204.51 J. Despite the decrease in tensile force strength properties in the manufactured nanocomposite with 0.15% SGO, it has exclusive flexibility properties such as a high required energy level for rupture of 5,576 times and a formability of 40% more than the base sample. It would be best to use NGORP manufactured from 0.015% nanosheets with exclusive properties rather than base samples for constructing parts and equipment, such as rebars, composite sheets, and transmission pipes, on offshore platforms.

• 한국세라믹학회지
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• 제45권9호
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• pp.561-566
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• 2008

Carbon fiber fabric-silicon carbide composites were fabricated by liquid silicon infiltration (LSI) process. The porous two-dimensional carbon fiber fabric performs were prepared by 13 plies of 2D-plain-weave fabric in a three laminating method, [0/90], [${\pm}45$], [$0/90/{\pm}45$] lay-up, respectively. Before laminating, a thin pyrolytic carbon (PyC) layer deposited on the surface of 2D-plain weave fabric sheets as interfacial layer with $C_3H_8$ and $N_2$ gas at $900^{\circ}C$. A densification of the preforms for $C_f-Si-SiC$ matrix composite was achieved according to the LSI process at $1650^{\circ}C$ for 30 min. in vacuum atmosphere. The bending strength of the each composite were measured and the microstructural consideration was performed by a FE-SEM.

• 한국공간구조학회논문집
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• 제10권2호
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• pp.117-126
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• 2010

본 논문은 복합재료 패널로 보강된 철근 콘크리트 보의 휨 실험과 해석을 통하여 패널의 보강효과에 대하여 알아보고자 한다. FRP 복합재료 패널은 전통적인 재료인 강재와 콘크리트에 비해 단위 무게당 강도 및 강성이 크고 부식에 대한 높은 저항성, 절연성, 고내구성 및 낮은 열전도성 등 우수한 물성으로 유지관리 측면에서 매우 유리하여 최근 많은 연구가 이루어지고 있다. 따라서 본 연구에서는 범용 유한요소 해석 프로그램인 ABAQUS를 이용하여 복합재료 패널로 보강된 철근 콘크리트 보의 극한 하중을 예측하고 실험을 수행하여 그 보강효과에 대한 고찰하였다. 복합재료 패널은 복합재료 패널 층의 유리섬유직조 형태에 따라 LT, DB, DBT로 구분하고 복합재료 패널의 층 개수에 따라 2ply, 3ply로 구분하였다. 실험을 수행한 결과, 해석과 일치하였으며 복합재료 패널로 보강한 철근 콘크리트 보가 극 한강도 측면에서 효율적이었다는 결론도 얻었다.

• Computers and Concrete
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• 제25권5호
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• pp.383-400
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• 2020

Due to higher stiffness to weight, higher corrosion resistance, higher strength to weight ratios and good durability, concrete composite structures provide many advantages as compared with conventional materials. Thus, they have wide applications in the field of concrete construction. This research focuses on the structural behavior of steel-tube CFRP confined concrete (STCCC) columns under axial concentric loading. A nonlinear finite element analysis (NLFEA) model of STCCC columns was simulated using ABAQUS which was then, calibrated for different material and geometric models of concrete, steel tube and CFRP material using the experimental results from the literature. The comparative study of the NLFEA predictions and the experimental results indicated that the proposed constitutive NLFEA model can accurately predict the structural performance of STCCC columns. After the calibration of NLFEA model, an extensive parametric study was performed to examine the effects of different critical parameters of composite columns such as; (i) unconfined concrete strength, (ii) number of CFRP layers, (iii) thickness of steel tube and (iv) concrete core diameter, on the axial load capacity. Furthermore, a large database of axial strength of 700 confined concrete compression members was developed from the previous researches to give an analytical model that predicts the ultimate axial strength of composite columns accurately. The comparison of the predictions of the proposed analytical model was done with the predictions of 216 NLFEA models from the parametric study. A close agreement was represented by the predictions of the proposed constitutive NLFEA model and the analytical model.

• 한국강구조학회 논문집
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• 제19권3호
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• pp.323-333
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• 2007

본 논문은 본 연구자가 기존에 발표한 모듈단면 프로파일보를 개선하여 새로운 모듈을 제안하였으며 이를 바탕으로 휨보강을 실시하여 적절한 휨보강 방법을 제시하고자 하였다. 개선된 모듈은 기존의 모듈보다 향상된 내력 및 초기강성을 나타냈다. 휨보강은 T형 단면 강재와 철근을 이용하여 실시하였으며 실험결과 철근을 이용하여 휨보강을 실시하는 것이 우수한 것으로 나타났다. 휨내력은 재료 실험결과를 바탕으로 이론값과 비교하면 저조한 결과를 나타냈으나 재료의 설계기준강도를 이용하면 90%정도의 내력을 나타내 향후 T형보를 이용한 압축측 보강이 이루어진다면 모듈단면 프로파일보의 적용가능성은 충분하다고 판단된다.

• 열처리공학회지
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• 제23권4호
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• pp.183-190
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• 2010

There are many methods to reduce the weight and the cost of the automobile body, among them, Tailor Welded Blank (TWB) is new welding method applied to body structure. It is necessary to evaluate mechanical properties of TWB structures or sheets for the application to automobile body parts. In this study, the stiffness of T-type and L-type joint structures, composite of TWB panel, which simplified two portions of side structure in automobile body were investigated. Additionally, the fatigue properties of TWB panels were obtained. Two types of welding technologies, laser and mash seam welding, were used to join mild panels with different thickness. This results are compared with conventional structures. The results are as follows: 1) The stiffness of joint structures, composite of TWB panel, is approximately 17% higher than that of conventional ones. 2) The location of welding line in TWB had a effect on the in plane bending stiffness, but not on the out of plane bending stiffness. 3) In terms of welding technology type, the mash seam welding show higher stiffness than the laser welding for in plane bending stiffness. But minimal differences in both types are revealed for out of plane bending stiffness. 4) The fatigue strength, composite of TWB panel, is lower than that of base steel. It is thought that defects in the welding zone had the action of notch in the fatigue test.