• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.343-346
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• 2010

형상기억합금이 삽입된 복합체는 힌지나 추가적 작동기 없이 그 자체로서 지능 구조의 역할을 할 수 있어 많은 분야에서 활발히 연구되고 있다. 본 논문에서는 형상기억합금(Shape Memory Alloy) 선이 삽입된 $\cap$자형 복합재를 제안하고, 형상기억합금과 모재가 정해진 경우의 곡률 변화에 영향을 주는 주요 설계 변수를 복합재의 너비, 두께, 형상기억합금의 편심률을 설계변수로 가정하고 유한요소 해석과 패널 제작 및 실험을 통해 검증한다. 먼저 라고다스(Lagoudas)모델을 형상기억합금의 구성방정식으로 이용한 유한요소해석모델을 구성하여 수치해석을 수행하고, 11 종류의 형상기억합금 선이 삽입된 유리섬유강화복합재(Glass Fiber Reinforced Plastic) 패널을 제작하여 열하중에 따른 곡률변화를 관찰한다. 해석결과와 실험결과의 비교를 통해 해석모델의 타당성을 검증하며, 해석을 통해 각 설계 변수들의 곡률변화에 대한 영향을 파악한다.

• International Journal of Naval Architecture and Ocean Engineering
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• v.6 no.3
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• pp.723-736
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• 2014

Glass Fiber Reinforced Plastic (GFRP) structures are primarily manufactured using hand lay-up or vacuum infusion techniques, which are cost-effective for the construction of marine vessels. This paper aims to investigate the mechanical properties and failure mechanisms of the hybrid GFRP composites, formed by applying the hand lay-up processed exterior and the vacuum infusion processed interior layups, providing benefits for structural performance and ease of manufacturing. The hybrid GFRP composites contain one, two, and three vacuum infusion processed layer sets with consistent sets of hand lay-up processed layers. Mechanical properties assessed in this study include tensile, compressive and in-plane shear properties. Hybrid composites with three sets of vacuum infusion layers showed the highest tensile mechanical properties while those with two sets had the highest mechanical properties in compression. The batch homogeneity, for the GFRP fabrication processes, is evaluated using the experimentally obtained mechanical properties.

• Journal of the Korean Society of Safety
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• v.9 no.1
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• pp.121-126
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• 1994

In this thesis, a series of loading tests are conducted in order to investigate the fracture safety as structural materials of GFRP(Glass Fiber Reinforced Plastics) which we wifely used in the developed countries becauses of their natural of anticorrosion and lightweight etc.. In the fracture test, the mid-span displacement, the strain and the yield load of the GFRP pipes are measured for different number of laminates, and fracture energy is estimated. From this study, it is known that GFRP pipe could be used as structural materials in underground buried pipes if their ductility and strength are increased by controlling number of laminates. Furthermore, because of their merit of lightweight, they can contribute greatly to reduction of construe-tlon cost when they are employed.

• Journal of the Korean Society of Safety
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• v.11 no.3
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• pp.154-159
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• 1996

In this thesis, a series of loading tests are conducted in order to investigate the fracture safety of GFRP(Glass Fiber Reinforced Plastics) pipes under fatigue load which are widely used in the developed countries becauses of their natural of anticorrosion and lightweight etc. . Fatigue test is performed by changing number of laminates and loading cycles to examine the flexural strains, the ductility and the fatigue strength for two million repeated loading cycles. From the fatigue test results, it was found that the larger the laminates of GFRP pipes is, the larger the stiffness of GFRP pipes under the fatigue load increases. This phenomenon is true until the fatigue failure. According to the S-N curve drawn by the regression analysis on the fatigue test results, the fatigue strength of percent of the static ultimate strength increases by increasing the laminates of GFRP pipes. The fatigue strength with two million repeated leading cycles in GFRP pipes with the laminates of GFRP pipes varing 15, 25, 35 shows about 75%, 80%, 84% on the static ultimate strength, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.5 no.1
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• pp.78-83
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• 1988

The purpose of this study is to understand the cutting characteristics of glass-fiber rein- forced plastic (GFRP) by investigating the variation of cutting force and surface roughness, depending on the amount fo flank wear and cutting conditions. And a Taylor type tool life equation is derived using the regression analysis. The present study reveals that, 1. Taylor's eqquation can be applicable to GFRP nd the constants n (0.170-0.175) and C (53.7- 64.4) are smaller than those in cutting of steel. 2. Principal cutting force increases sharply with the increase of feed rate, but feed force and radial force are almost constant. This result is quite different from that of metal cutting. 3. Cutting forces ($F_P, \;F_Q, \;F_R$) increase with the increase of flank wear, and feed force especially increases sharply with the increase of flank wear. 4. Surface roughness changes very much along the circumference of the workpiece and the amount of flank wear has almost no effect on surface roughness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.710-715
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• 1997

This paper deals with the analysis of the optimum value of honeycomb core considering variable design parameter. As thickness and height of core rises in design parameter, natural frequency of laminated composite plate increases. The angle-phy has the maximum value when the plate of honeycomb core join to opposite direction. This paper shows that the natural frequency of CFRP was higher than that of GFRP and mode shapes were various at angle-ply.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.38-38
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• 2000

저온유지장치에서 요구되는 도달압력은 초전도 코일의 냉각시스템과 저온유지장치의 벽 사이의 진공단열조건으로부터 결정될 수 있으며, 기체에 의한 열전도의 영향을 방지하기 위해서는 5$\times$105Torr 이하의 진공도가 요구된다. 저온유지장치 내에서 진공 단열재로 사용되는 Glass Fiber Reinforced Plastic(GFRP)과 Carbon Fiber Reinforced Plastic(CFRP)의 기체 방출률을 측정하였다. 고출력 토카막 방전동안 graphite limiter 표면의 온도는 200$0^{\circ}C$ 이상이며, 플라즈마로 유입되는 불순물의 양을 줄이기 위해 많은 시도를 하고 있다. 상온에서부터 약 100$0^{\circ}C$까지 승온에 따른 방출기체의 양 및 성분 분석, annealing 후 공기 중에 약 2주간 노출 후 기체 방출률과 성분을 분석하였다. 총 기체 방출량은 10$0^{\circ}C$ 근방에서 급격히 증가하여 $600^{\circ}C$부터는 graphite의 종류에 관계없이 거의 일정한 분포를 보이며, 최대 방출률은 약 20$0^{\circ}C$~30$0^{\circ}C$ 부근에서 나타났다.

• 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.

• Composites Research
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• v.36 no.1
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• pp.37-41
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• 2023

The treated water inside the ballast electrolytic cell creates a highly alkaline atmosphere due to hydroxide generated at the DSA(Dimension Stable Anode) electrode during electrolysis. In this study, a composite material that can replace the weakness of the PE-coated steel pipe used in the existing ballast pipe was prepared. The test samples are BRE(Basalt fiber reinforced epoxy), BRP(Basalt fiber reinforced unsaturated polyester), GRE(Glass fiber reinforced epoxy), and GRP(Glass fiber reinforced unsaturated polyester). And then it was immersed in NaOH for 720 hours. The friction test of each specimen was conducted. The Friction coefficient analysis according to material friction depth and interfacial adhesion behavior between resin and fiber were analyzed. As a result, the mechanism of interfacial separation between resin and fiber could be analyzed. In the case of the unsaturated polyester resin with low interfacial bonding strength the longer the immersion time in the alkaline solution, the faster the internal deterioration caused by the deterioration that started from the surface, resulting in a decrease in the friction coefficient. It is hoped that this study will help to understand the degradation behavior of composite materials immersed in various chemical solutions such as NaOH, acid, and sodium hypochlorite in the future.

• Computers and Concrete
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• v.25 no.4
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• pp.369-382
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• 2020

This paper presents a discussion of the Finite Element Analysis (FEA) when applied for the analysis of concrete elements reinforced with glass fibre reinforced polymer (GFRP) bars. The purpose of such nonlinear FEA model development is to create a tool that can be used for numerical parametric studies which can be used to extend the existing (and limited) experiment database. The presented research focuses on the numerical analyses of concrete beams reinforced with GFRP longitudinal and shear reinforcements. FEA of concrete members reinforced with linear elastic brittle reinforcements (like GFRP) presents unique challenges when compared to the analysis of members reinforced with plastic (steel) reinforcements, which are discussed in the paper. Specifically, the behaviour and failure of GFRP reinforced members are strongly influenced by the compressive response of concrete and thus modelling of concrete behaviour is essential for proper analysis. FEA was performed using the commercial software ABAQUS. A damaged-plasticity model was utilized to simulate the concrete behaviour. The influence of tension, compression, dilatancy, mesh, and reinforcement modelling was studied to replicate experimental test data of beams previously tested at the University of Waterloo, Canada. Recommendations for the finite element modelling of beams reinforced with GFRP longitudinal and shear reinforcements are offered. The knowledge gained from this research allows for the development of a rational methodology for modelling GFRP reinforced concrete beams, which subsequently can be used for extensive parametric studies and the formation of informed recommendations to design standards.