In the present work, multi-walled carbon nanotubes (MWCNT) were anchored with the assistance of vinyl ester resin (VE) on the carbon fiber surfaces of conventional carbon fabrics (CCF) and semi-spread carbon fabrics (SSCF) having different areal density, ply thickness, and crimp number, respectively. Here, MWCNT anchoring means that MWCNT were physically attached on the individual carbon fiber surfaces of each fabric by coating with dilute VE and then by thermally curing it. The MWCNT anchoring effect on the interlaminar shear strength (ILSS) of CCF/VE and SSCF/VE composites was investigated. MWCNT were also simply applied (without physical attachment) to the carbon fiber surfaces of CCF and SSCF for comparison, respectively. It was found that SSCF/VE composites exhibited the ILSS higher than CCF/VE composites, regardless of simple-applying or anchoring of MWCNT, increasing the ILSS with the MWCNT concentration. It was noted that MWCNT anchoring was effective to improve not only the interlaminar adhesion but also the interfacial bonding between the carbon fiber and the matrix due to the formation of MWCNT bridges between the individual carbon fibers of SSCF, indicating that the MWCNT anchoring effect was more pronounced with SSCF than with CCF. The result of the interlaminar property was well supported by the fiber and composite fracture topography.

Nowadays, the study of CFRP reinforced with carbon fiber is focused on improving the the mechanical property. The study on the fracture data of CFRP are not properly made out than that of the general mechanical joint. In this study, the fracture property of mode 1 at the same condition of tensile experiment is investigated by applying the layer angle to laminated CFRP with the thickness of 15 mm. When the reaction forces until dropping out the bonded surface are compared with the cases of the layer angles of 0°, 45° and 60°, the reaction force is shown to be most and the elapsed time until dropping out the bonded surface is longest at that of 45°. The deformation energy is also shown to have the highest value by dropping out the adhesive interface. As the basis of the analysis result of this study, the most safety with fracture resistance is shown in the case of 45°. the bonded structure applying the appropriate layer angle is thought to have the structural safety.

본 연구에서는 반구형과 평탄형의 비상체를 이용하여 일반콘크리트와 섬유보강콘크리트에 충격시험을 진행한 후 파괴깊이와 형 태, 파괴직경, 배면의 인장변형을 평가하였다. 선단면적이 작을수록 충격력의 집중에 의해 파괴깊이는 크고 표면파괴 직경은 작게 되는 것으로 확인되었다. 반면에 선단면적이 클수록 파괴깊이는 작지만 표면파괴직경은 크게 되었다. 일반콘크리트와 섬유보강 콘크리트에서 유사한 표 면파괴와 배면변형이 발생하였으나 인장변형의 크기는 일반콘크리트에 비해 섬유보강 콘크리트가 작은 것으로 나타났다. 또한, 비상체의 선 단형상에 따른 표면관입의 형태와 배면의 인장변형 사이에 직접적인 연관이 있는 것으로 사료된다. 따라서 콘크리트의 배면박리한계두께 예 측 시에는 표면관입깊이뿐만 아니라 배면의 변형거동 또한 고려할 필요성이 있을 것으로 사료된다.

In this study, local fracture of concrete was evaluated through high-velocity impact test. As results, increase of bending tension performance by fiber reinforcement did not affect penetration depth Control, but it decreased rear side fracture thickness and diameter. Therefore, it was observed that fiber reinforcement decreases scabbing limit thickness.

새로운 재료의 적용 실험을 통하여, 탄소섬유 분말 혼입 모르타르 복합 구조체의 파괴예측 자가진단 적용 특성에 대해 검토하였다. 본 연구에서는 자가진단 성능을 부여하기 위해 코크스와 탄소섬유분말(미분쇄 탄소섬유)이 혼입된 전도성 모르타르의 개발 및 자가진단 재료로서의 사용이 제안되었다. 각 하중재하단계에서의 균열발생 전후의 전기저항값과 AE특성치의 변화특성 시험을 통해, 이들 각 인자의 상호 연관성을 검토하였다. 그 결과, 코크스와 탄소섬유분말(미분쇄 탄소섬유)을 사용하여 새롭게 제안된 복합재료는 모르타르 시험체의 파괴 자가진단에 사용이 가능함을 알 수 있었다.