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금속/폴리머 샌드위치 복합재의 기계적 특성 및 범퍼 응용 연구
공경일(Kyungil Kong),박형욱(Hyung Wook Park),경규형(Gyouhyoung Kyung),이규세(Gyuse Lee),서종덕(Seo Jong Duk) 한국자동차공학회 2011 한국자동차공학회 지부 학술대회 논문집 Vol.2011 No.10-2
Recently, the reduction of the vehicle weight is the critical factor to enhancing the fuel efficiency of the passenger cars. Therefore, the lightweight materials have been adopted to the automotive components. However, although the vehicle weight reduces, the overall stiffness should be equal to the steel based automotive components due to the safety of drivers and passengers. One of the good candidates for the lightweight materials satisfy both requirements is the metal/poylmer sandwich. In this study, the static stiffness of this metal/polymer sandwich was experimentally observed with comparison with various steels. Its ratio of impact energy absorption has also been investigated and compared with that of the steels. In addition, the finite element analysis of the front bumper based on the metal/polymer composite has been performed to identify variation of its static stiffness
공경일(Kyungil Kong),권오범(O Bum Kwon),박형욱(Hyung Wook Park) 대한기계학회 2017 大韓機械學會論文集A Vol.41 No.2
최근 자동차 산업에서 경량화이면서 외부 충격에 민감한 시트 프레임은 안전성을 고려하여 꾸준히 연구개발되고 있다. 특히 본 연구에서는 고장력 강판과 폴리머의 이종 소재를 이용한 시트 프레임의 충격 특성에 대해 살펴보았다. 또한, 충격시 변위는 소재에 대해 굽힘 현상을 고려한 등가 굽힘강성식을 도입하여 살펴보았다. 층간 wire-web 구조물의 다양한 형상의 공학 디자인을 통해 충격시 변화가 적은 디자인을 설계하였으며, 육각형의 층간 wire-web 구조물이 외부 충격대비 안전계수가 높음으로 인해 흡수능력이 향상될 것으로 기대하고 있다. 이러한 연구 결과를 토대로 층간 wire-web 구조물의 설계를 통해 레진과의 함침을 높이고 이종 소재로써의 충격민감도에 유리한 제품을 개발할 수 있을 것으로 사료된다. Recently, the reduction of vehicle weight has been increasingly studied, in order to enhance the fuel efficiency of passenger cars. In particular, the seat frame is being studied actively, owing to considerations of driver safety from external impact damage. Therefore, this study focuses on high strength steel sheet (SPFC980)/polymer heterojunction hybrid materials, and their performance in regards to impact energy absorption. The ratio of impact energy absorption was observed to be relatively higher in the SPFC980/polymer hybrid materials under the impact load. This was found by calculating the equivalent flexural rigidity, which is the bending effect, according to the Castigliano theorem. An efficient wire-web structure was investigated through the simulation of different wire-web designs such as triangular, rectangular, octagonal, and hexagonal structures. The hexagonal wire-web structure was shown to have the least impact damage, according to the simulations. This study can be utilized for seat frame design for passengers" safety, owing to efficient impact absorption.
SnO₂로 표면개질한 탄소섬유 층간 발열 및 기계적 물성 향상
공경일(Kyungil Kong),박형욱(Hyung Wook Park) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
In this research, functional composites were manufactured using carbon fiber and SnO₂ nanomaterials. As for functional properties of composites, carbon fiber was tailored with SnO₂ nanomaterials. Electrical thermal heat was shown prevailed in SnO₂ modified carbon fiber composites compared to bare carbon fiber composites. Impact absorbing and strength were shown higher for SnO₂ modified carbon fiber composites. These experimental results were induced by the reason that interlocking branches among SnO₂ nanomaterials yielded secondary reinforcements surrounding carbon fiber and polymer. As molar concentration of SnO₂ increased, Joule heating and mechanical properties were increased. To support these results, SEM images were observed to be distinct in morphology characteristics. X-ray diffraction analysis was used to characterize the crystallinity and SnO₂ concentration. Impact characterization for prepared samples was observed by drop down impact tester. Furthermore, shear properties by loading uniaxial tensile load was observed by ASTM Standard D3518/D3518M-13.
열에너지 수확용 멀티스케일 및 섬유강화 복합재의 열전 특성 평가
성대한(Dae Han Sung),강구혁(Gu-Hyeok Kang),공경일(Kyungil Kong),김명수(Myungsoo Kim),박형욱(Hyung Wook Park),박영빈(Young-Bin Park) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
In this research, two kinds of multifunctional materials that serve as not only structural but also thermoelectric materials were manufactured, and their applicability was assessed as thermoelectric materials. One is multiscale composite (carbon nanotubes(CNT)/glass fabric(GF)/epoxy) and the other is fiber-reinforced composite (carbon fiber(CF)/epoxy). GF/epoxy composites containing various contents of CNT were prepared by calendering with a threeroll-mill followed by a hand-layup process on a hot plate. Experiments confirmed that the electrical conductivity of multiscale composites increases as CNT concentration increases. In-plane thermal and electrical conductivities of multiscale and fiber-reinforced composites are higher than those in through-thickness direction due to the alignment effect of CNTs and continuity of woven fabric. In most cases, conductivities of fiber-reinforced composites are higher than those of multiscale composites. Calculating the Seebeck coefficients, we concluded that multiscale composites behave as n-type thermoelectric materials and fiber-reinforced composites showed p-type nature. Closed circuit consisting of two different types of materials showed appreciable electric currents in the presence of temperature gradients.