• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.04a
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• pp.83-86
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• 2003

동시경화조인트는 경화 시 복합재료로부터 흘러나오는 수지를 접착제로 사용하기 때문에 제조과정이 간편할 뿐 아니라 복합재료를 표면 처리할 필요가 없기 때문에 기존의 접착제에 의한 접합방법에 비해 장점을 지닌다. 최근 동시경화조인트에 관한 연구가 활발하게 진행되고 있으나 해석적인 방법을 통한 연구는 아직까지 미비하다. 실험적으로 연구된 결과를 보면 동시경화 조인트는 계면 모서리에서 파괴가 시작되어 계면을 따라 파괴가 진행된다. 그러므로 조인트의 계면 모서리에서의 응력집중계수에 관해 연구하는 것이 중요하다. 본 논문에서는 고유치 문제를 고려하여 복합재료와 강재료로 구성된 동시경화조인트의 계면 모서리에서 발생하는 응력 및 변위장을 결정하고, H-적분을 이용하여 응력집중계수를 구하는 방법을 제시하고자 한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.3
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• pp.315-321
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• 2010

Co-cured single lap joints under cyclic tensile loads fail initially at the tip of the interface corner between the two adherents. The failure mechanism is complex because it is related to corrosion fatigue. Corrosion behavior at the interface affects the failure of the joints because corrosion deteriorates fatigue resistance. In this study, we clarified the cause of interfacial corrosion in co-cured single lap joints under cyclic tensile loads. The failure mechanism was also analyzed by observing the failed surfaces of specimens and the stress distribution along the interface. The surface roughness at the interface and the stacking sequence of the composite adherent were examined to investigate their effects on failure of the joint.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.78-82
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• 2004

The co-cured joint has been widely used in joining process of composite structures due to its simple and easy manufacturing process. In this paper, the effect of stacking sequence of the carbon epoxy prepreg, bonding length and thickness of the aluminum plate on the static tensile load capability of the co-cured aluminum-composite double lap joint were experimentally investigated. From experimental results, the optimum EA ratios with respect to stacking sequence and bonding length of the co-cured joint were obtained, which may be useful for the joining of hybrid structures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1203-1214
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• 2000

In this paper, a failure model for co-cured steel-composite tubular single lap joints has been proposed incorporating the nonlinear mechanical behavior of steel adherends and different failure mode s such as steel adherend failure and composite adherend failure. The characteristics of the co-cured steel-composite tubular single lap joint were investigated with respect to the test temperature, the stacking sequence of composite adherend, the thickness ratio of steel adherend to composite adherend, and the scarf ratio of steel adherend. Thus, the optimum design method for the co-cured steel-composite tubular single lap joint was suggested.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.409-417
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• 2003

Cure monitoring can be used to improve the quality and productivity of thermosetting resin matrix composite products during their manufacturing process. In this work, the sensitivity of dielectrometry was improved by adequate separation the efforts of sensor and externals on the measured signal. A new algorithm to obtain the degree of cure during dielectric cure monitoring of glass/polyester and glass/epoxy composites was developed by employing a function of both temperature and dissipation factor, in which five cure monitoring parameters were used to calculate the degree of cure. The decreasing pattern of dissipation factor was compared with the relationships between the degree of cure and the resin viscosity. The developed algorithm might be employed for the in situ cure monitoring of thermosetting resin composites.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.10a
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• pp.95-98
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• 2001

Co-cured joining method is an efficient joining technique because both curing and bonding processes for the composite structures can be achieved simultaneously. It requires neither an adhesive nor a surface treatment of the composite adherend because the excess resin, which is extracted from composite materials during consolidation, accomplishes the co-cured joining process. In this paper, we considered three bond parameters, affecting tensile load bearing capacity of the co-cured single and double lap joints. Filially, we nave presented optimal bonding conditions for co-cured single and double lap joints with steel and composite adherends under tensile loads.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.3
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• pp.385-392
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• 1997

The joint design and manufacture of the composite structure have become an important research area because the structural efficiency of the composite structure is often determined by its joint not by its basic structure. The co-cured joint is an efficient joint technique because both curing and jointing for composite structures are achieved simultaneously. In this paper, the torque capacities of the co-cured tubular lap joint with and without knurling of the pyamid type were experimentally measure. From the experimental resuts, it was found that the excess resin played a role as an adhesive in the co-cured tubular lap joint whose steel adherends were not knurled. Also, it was found that the torque capacity of the co-cured joint was increased as the knurling size of the pyramid type on the surface of the steel adherend was increased.

• Composites Research
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• v.29 no.6
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• pp.395-400
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• 2016

Recently, many research groups have studied on the epoxy-based multifunctional electrolyte to develop the structural composite bearing high mechanical properties without sacrificing the ionic conductivity at the same time. The studies on the optimal content and material selection for structural electrolyte have been published, while its curing behavior has not much analyzed yet. In this study, epoxy-based structural electrolyte containing solid electrolyte was prepared by varying the curing temperature and time. In addition, the ionic conductivities and mechanical properties of specimens were measured. We also find out the optimal hardening condition where the epoxy domain enables to be hardened within the range of temperature at which the thermal decomposition of electrolyte does not occur. Finally, we propose the multifunctional structural electrolyte showing achievable electrical and mechanical properties (282 MPa and $9{\times}10^{-6}S/cm@25^{\circ}C$).

• Composites Research
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• v.24 no.5
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• pp.23-28
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• 2011

In this paper, the bonding strengths of co-cured T800 carbon/epoxy composite-aluminum single lap joints with and without additional pressures were investigated using the pressure information induced by the fiber tension during a filament winding process. The specimens of all the tests were fabricated by an autoclave vacuum bag de-gassing molding being controlled forming pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa including vacuum). A special device which can act uniform additional pressures on the joining part of the single lap joint specimen was designed to measure the bonding strengths of composite-aluminum liners of type III hydrogen pressure vessel fabricated by a filament winding process. After the three different additional pressures (absolute pressures of 0.1MPa, 0.3MPa and 0.7MPa) were applied to the specimens the effect of the additional pressures on the bonding strengths of the co-cured single-lap joints were evaluated.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2001.05a
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• pp.172-175
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• 2001

The co-cured Joining method, which is regarded as an adhesively bonded Joining method, is an efficient joining technique because both curing and bonding processes for the composite structures can be achieved simultaneously. It requires neither surface treatment onto the composite adherend nor an additional adhesive joining process because the excess resin, which is extracted from composite materials during consolidation, accomplishes the co-cured Joining process. Since the adhesive of the co-cured joint is the same material as the resin of the composite adherend, the analysis and design of the co-cured joint for composite structures are simpler than those of an adhesively bonded joint, which uses an additional adhesive. In this paper, effects of the manufacturing parameters, namely surface roughness, stacking sequence of the composite adherend, and manufacturing pressure in the autoclave during curing process, on the tensile load bearing capacity of the co-cured single lap joint will be experimentally investigated.