http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
고온 성형을 이용한 인코넬 718 샌드위치 코어 구조 성형
유준태(Joon-Tae Yoo),윤종훈(Jong-Hoon Yoon),이호성(Ho-Sung Lee) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
In this study, flat core structure is formed using alloy 718 by hot gas forming at 980C. Initial blank is composed of 2 sheets which are welded by electron beam welding to get core pattern. To prevent the separation at welding joint during forming, welding width is increased by multi-pass welding. Maximum forming pressure is limited 48 bar considering the strength of die and capacity of pressurization system. Forming process is analyzed by numerical method. Flow stress equation is determined by free bulging test and it is a function of strain-rate sensitivity and strength coefficient. 2D and 3D models are used for analysis and its results are compared with experimental results in deformed shape. Analysis using 3D model shows good agreement. In case of 2D model, it has a little difference because model is considered as plane strain. But it will be more useful using 2D model to save computational cost and to find the response in various boundary conditions.
알루미늄 Isogrid 패널의 좌굴시험 및 비선형 해석
유준태(Joon-Tae Yoo),이종웅(Jong-Woong Lee),윤종훈(Jong-Hoon Yoon),장영순(Young-Soon Jang),이영무(Yeong-Moo Yi),조광래(Gwang-Rae Cho) 한국항공우주학회 2005 韓國航空宇宙學會誌 Vol.33 No.4
압축하중을 받는 실린더형 구조물에 대한 보강방법으로는 스킨-스트링거, 격자보강 형상 등 여러 종류가 있다. 그 중 isogrid 형상은 정삼각형형태의 보강대가 반복되는 보강구조로서 여러 가지 조합하중 및 집중하중에 대한 대처능력이 우수한 보강구조이다. 본 논문에서는 격자보강 구조 중 isogrid 구조에 대한 압축 좌굴시험 및 비선형 해석을 수행하였다. Isogrid 패널은 두께가 11.43 ㎜, 높이가 660 ㎜, 외경이 2.4 m이며 70도의 원호를 이루는 알루미늄합금 일체형 구조이다. 시편에 대한 압축 좌굴시험을 통하여 국부 좌굴강도, 전체좌굴강도, 국부좌굴후의 거동 등을 확인하였다. 또한 MSC/MARC를 이용한 비선형 FEM 해석을 수행하여 구조시험 결과와 비교하였다. 해석 시에는 패널의 소성가공 시 발생한 형상공차를 고려하였다. 시험결과와 해석결과는 좌굴하중 및 좌굴모드가 모두 비교적 일치하였다. There are many methods to reinforce the cylindrical structure for light weight design like skin-stringer and semi-monocoque. Isogrid is one of the reinforced structures to improve buckling load. Isogrid has many advantages for complex load case, internal pressure and concentrated load. In this paper, compressive buckling test and non-linear FE analysis of the isogrid panel are described. Diameter of panel is 2.4m and thickness of plate is 1l.43㎜. The angle which the panel accomplish is about 70 degrees and, its height is about 660㎜. Local buckling, global buckling and variation of stiffness after local buckling were observed during buckling test of the panel. MSC/MARC is used for non-linear FE analysis. When analysis, initial imperfection of panel which occurred during plastic forming is considered. The results of analysis for buckling mode and buckling load have good agreements with test.
접합툴의 형상에 따른 Al-Li합금의 마찰교반용접특성 고찰
유준태(Joon-Tae Yoo),윤종훈(Jong-Hoon Yoon),이호성(Ho-Sung Lee) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Al-Li alloys show extraordinary specific strength and have been used in Space Shuttle SLWT(Super Lightweight Tank) with application of Friction stir welding (FSW). FSW has many advantages like the absence of porosity, distortion and residual stresses which are typical defects of the fusion welding processes. The process uses a rotating tool with a profiled pin that penetrates the parts to be joined; the tool then starts to travel along the joint line. By keeping the tool rotating and moving it along the joint line to be welded, the softened material due to the frictional heat is stirred and mechanically mixed together by the rotating pin forming a weld in solid state without melting. The present work is to investigate the effect of tool configuration on the microstructure and mechanical properties of friction stir welded AA2195. Since the mechanical properties of the joint are related with development of microstructure evolution during FSW, microstructure and mechanical properties of joints were investigated for different tool configuration.