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김윤해(Yun-Hae Kim),배성열(Sung-Youl Bae),김국진(Kook-Jin Kim),한중원(Joong-Won Han),우병훈(Byung-Hoon Woo),문경만(Kyung-Man Moon) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.6
Now, Composite materials are widely used because of their high specific strength and specific stiffness in marine, infrastructure applications, lesure. However, it is known that long term or short term exposure of fiber reinforced composite laminates to the moisture environments could change its chemical and physical properties irreversibly. In this study, effects of moisture absorption in various moisture environments were investigated. The results show that the mechanical properties of FRP are decreased with immersion time. Moreover, the mechanical properties of FRP are recovered throughout drying process in drying oven at 80℃.
라미네이트 복합재료의 미세조직 및 파단면 거동과 수분 환경에서 물성저하와의 상호연관성
김윤해(Yun-Hae Kim),김동훈(Dong-Hun Kim),배성열(Sung-Youl Bae),김국진(Kook-Jin Kim),한중원(Joong-Won Han) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
The object of this study is to find out the relationship between degradation of FRP and their micrographic structure in the hot/ wet environments. In this study, carbon/ epoxy and glass/ epoxy FRP specimens were manufactured and the manufactured conditions of two types of specimens were same. The manufactured specimens were immersed in 90℃ water bath during 50 days and moisture contents, tensile strength were periodically monitored. Moreover, the micrographic structure and fractographic were observed at the same term. As a result, the degradation of FRP specimens were directly influenced their pull-out and swelling phase in the moisture environments. Moreover, it was thought that the cracks and their prepagations in the specimens played a important part in their degradation by moisture absorbtion.
3D Textile 프리폼 제조 및 복합재료 기계적 특성 연구
조광훈 ( Kwang-hoon Jo ),( Vinzenz Klapper ),김현우 ( Hyeon-woo Kim ),이정운 ( Jeong-woon Lee ),한중원 ( Joong-won Han ),변준형 ( Joon-hyung Byun ),조치룡 ( Chee-ryong Joe ) 한국복합재료학회 2019 Composites research Vol.32 No.1
항공기 복합재료 날개 구조는 대부분 접착 혹은 패스너로 체결되어 있는데, 이러한 적층 구조 복합재료는 층간 강도가 취약하여 층간 분리가 일어나기 쉽다. 이러한 적층 복합재료의 단점을 보완하기 위해 두께 방향의 섬유를 보강한 3차원 직조형 복합재료를 통하여 강도, 손상 내구성, 충격 및 피로 하중을 향상시킬 수 있다. 또한, 자동화된 직조 공정에 의하여 단일 구조 near-net-shape의 프리폼 제조가 가능하기 때문에 공정 단축, 체결 부품 감소로 복합재료 전체 가격을 절감할 수 있다. 따라서 본 연구에서는 3차원 직조형 복합재료의 항공기 구조물적용 가능성을 확인하기 위하여 3차원 프리폼의 기본적인 구조인 orthogonal(ORT), layer-to-layer(LTL), through-thethickness(TTT) 패턴을 직조하고 이를 복합재료로 성형하여 압축 시험, 인장 시험, Open-hole 인장 시험을 하였다. 이 중 orthogonal 직조 복합재료가 인장 및 압축 탄성계수와 강도 모두 가장 높았으며 노치 민감도에서도 orthogonal 복합재료가 일방향 적층복합재료나 패브릭 적층 복합재료에 비하여 가장 우수한 특성을 보였다. The aircraft composites wing parts are usually integrated with adhesive or fastener. These laminated composites have weak interlaminar strength, which can lead to delamination. In order to compensate the disadvantages of laminated composites, it is possible to improve the strength, durability, shock and fatigue resistance by reinforcing the fiber in the thickness direction. In addition, using a single structure near-net-shape saves the manufacturing time and the number of fasteners, thus can reduce the overall cost of the composite parts. In this study, compression test, tensile test and open-hole tensile test are carried out for three structural architecture of 3D (three-dimensional) textile preforms: orthogonal(ORT), layer-to-layer(LTL) and through-the-thickness(TTT) patterns. Among these, the orthogonal textile composite shows the highest Young’s modulus and strength in tensile and compression. The notch sensitivity of the orthogonal textile composite was the smallest as compared with UD (unidirectional) and 2D (two-dimensional) fabric laminates.