• 대한금속재료학회지
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• 제49권8호
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• pp.589-595
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• 2011

Laminated glass fiber-reinforced plastic (GFRP) composites were applied to an insulating structure of a magnet system for a nuclear fusion device. Decreased inter-laminar strength by a strong repulsive force between coils which is induced a problem of structural integrity in laminated GFRPs. Therefore, it is important to investigate the inter-laminar characteristics of laminated GFRP composites in order to assure more reliable design and better structural integrity. Three types of the laminated GFRP composites using a high voltage insulating materials were fabricated according to each molding process. To evaluate the grade of the fabricated composites, mechanical tests, such as hardness, tensile and compressive tests,were carried out. The autoclave molding composites satisfied almost of the mechanical properties reguested at the G10 class standard, but the vacuum impregnation (VPI) and Prepreg composites did not.

• Composites Research
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• 제13권3호
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• pp.21-29
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• 2000

The optimum design of hybrid laminated composites for iso-strain structure has been studied by controling fiber orientations and thicknesses of each layer. Fiber orientations and thicknesses of each layer for iso-strain structure were designed. Combining the laminates of each layer of different reinforcing material, the constitutions of hybrid laminated composite for iso-strain structure were obtained. All these calculations were formed on computer systems, automatically for the hybridization. Using the data of some specific laminated composite such as glass and aramid reinforced composites, the constitutions of hybrid laminated composites for iso-strains structure were designed and verified by lamination theory. The strains of each layer of hybrid laminated composites are calculated and they turned out to be good agreements with the results obtained lamination theory.

• 한국재료학회지
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• 제5권8호
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• pp.979-987
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• 1995

탄소섬유와 epoxy 수지의 prepreg로 성형된 Cross형 적층판 복합재료에서 unfit ply의 두께가 복합재료의 기계적 성질에 미치는 영향과, unidirectional prepreg 및 fabric prepreg로된 적층판의 기계적 성질의 차이를 비교 검토하였다. 그 결과 unit ply의 두께가 두꺼울수록 면내전단강도는 작아졌으며, 면내전단강도가 작아 질수록 층간박리 현상이 현저하게 나타났다. 또 적당한 층간박리의 발생은 파괴인성치와 층격치를 증가시키지만 심한 층간박리는 오히려 그 값들을 감소시켰다. 그리고 unidirectional prepreg로 성형된 적층판이 fabric prepreg로 성형된 적층판보다 인장강도, 파괴인성치, 파괴일 및 충격치 등의 기계적 성질이 우수했다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.237-240
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• 2004

High strain-rate deformation behavior of NiAl/Ni micro-laminated composites was characterized by split hopkins on pressure bar(SHPB). When the strain rate increased, the compressive stress of micro-laminated composites were increased a little. When the intermetallic volume fraction increased, the compressive stress of micro-laminated composites increased linearly irrespective of strain rate. Absorbed energy during the quasi-static and SHPB tests was calculated from the integrated area of stress-strain curve. Absorbed energy of micro-laminated composites deviated from the linearity in terms of the intermetallic volume fraction but merged to the value of intermetallic as the strain rate increased. This was due to high tendency of intermetallic layer for the localization of shear deformation at high strain rate. Microstructure showing adibatic shear band(ASB) confirmed that the shear strain calculated from the misalignment angle of each layer increased and ASB width decreased when the intermetallic volume fraction. Simulation test impacted by tungsten heavy alloy cylinder resulted that the absorbed energies multiplied by damaged volume of micro-laminated composites were decreased as the intermetallic volume fraction increased. Fracture mode were changed from delamination to single fracture when the intermetallic volume fraction and this results were good matched with previous results[l] obtained from the fracture tests.

• 대한기계학회논문집
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• 제7권2호
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• pp.130-137
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• 1983

Laminated steel composites are made from spring steel and mild steel by rolling process. Experiments for impact test are carried out and the fracture behavior of laminated steel composites are compared with that of homogeneous steel. Also, fracture models of laminate composites are analyzedby finite element method and the computed fracture stress is compared with experimental results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.345-348
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• 2004

In this paper it is to establish a comprehensive model for predicting damping in sandwich Laminated composites on the basis of strain energy method. In this model, the effect of transverse shear on the material damping has been considered with in-plane stresses. Results showed that the viscoelastic core thickness in the sandwich beam and the Length of a beam have a high impact on the material damping. The transverse shear appears to be highly influenced by the damping behavior in $0^0$ laminated sandwiched composites. However, it is Little influenced by that in $90^0$ laminated sandwiched composites.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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• pp.31-35
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• 2006

Degradation characteristics of filament-winded composites due to accelerated environmental aging have been evaluated under high temperature, water immersion and thermal impact conditions. Two kinds of laminated composites coated by an urethane resin have been used: carbon-fiber reinforced epoxy(T700/Epon-826, CFRP) and glass-fiber reinforced phenolic (E-glass/phenolic, GFRP). For tensile strength of $0^{\circ}$ composites, CFRP did high reduction by 25% under the influence of high temperature and water while CFRP showed little degradation. However for water-immersed $90^{\circ}$ composites both CFRP and GFRP showed high reduction in tensile strength. Bending strength and modulus of $90^{\circ}$ composites were largely reduced in water-immersion as well as high temperature environment. Urethane coating on the composite surface improved the bending properties by 20%, however hardly showed such improvement for water-immersed $90^{\circ}$ composites.

• 항공우주시스템공학회지
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• 제1권4호
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• pp.28-36
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• 2007

This paper presents critical buckling loads of laminated composites under cylindrical bending. In-plane displacements are assumed to vary exponentially through plate thickness. The accuracy of this theory is examined for symmetric/antisymmetric cross-ply, angle-ply and unsymmetric laminates under cylindrical bending. Analytical solutions are provided to investigate the effect of transverse shear deformation on critical buckling loads of the laminated plates, and the results are compared with those obtained from the first-order shear deformation plate theory and the classical laminated plate theory.

• Structural Engineering and Mechanics
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• 제70권2호
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• pp.233-243
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• 2019

This paper depicts the development and characterizations of laminated composites made with cellulosic giant cane (Arundinaria gigantea) fiber mats and epoxy resin. Zirconia-toughened mullite (ZTM) is used as a filler material in the laminated composite which was prepared from sillimanite through plasma processing technique. The mechanical characterizations of this composite have been carried out as per ASTM standards to evaluate its usability as a structural material. The effects of varying weight percentages of the filler and two different fiber orientations namely, angle-ply [$+45^{\circ}/-45^{\circ}/+45^{\circ}$] and balanced cross-ply [$0^{\circ}/90^{\circ}/0^{\circ}$] on the physical and mechanical properties such as density, microhardness, impact strength, tensile strength and interlaminar shear strength of the layered composite specimens have been investigated. The study indicates that the inclusion of zirconia-toughened mullite in the composite laminate as filler improves its mechanical properties. Moreover, the use of giant cane fiber mat in the laminate is more eco-friendly than the synthetic fibers. This research also helps in generating additional data to enrich the repository of natural fiber reinforced laminated composites.

• International Journal of Aeronautical and Space Sciences
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• 제11권3호
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• pp.155-166
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• 2010

I review research on self-sensing and structural optimizations of laminated carbon/epoxy composites in Japan. Self-sensing is one of the multiple functions of composites; i.e., carbon fiber is used as a sensor as well as reinforcement. I present a controversial issue in self-sensing and detail research results. Structural optimization of laminated CFRP composites is indispensable in reducing the weights of modern aerospace structural components. I present a modified efficient global search method using the multi-objective genetic algorithm and fractal branch and bound method. My group has focused its research on these subjects and our research results are presented here.