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A Numerical Study on The Three Point Bending Behavior of AluminumFoam Filled Stainless Steel Tube
Md Anwarul Hasan(하산),Amkee Kim(김엄기),Seong-Sik Cheon(전성식),Chang-Hun Lee(이창훈),Hyo-Jin Lee(이효진),Seong-Seock Cho(조성석) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
A comprehensive numerical study on the three point bending behavior of Aluminum foam-filled stainless steel tube has been performed. Aluminium alloy foams with various densities were produced and their mechanical properites were evaluated. Finite element(FE) analysis of three point bending test was performed to evaluate bending behavior of foam filled cylindrical structures. Results showed that foam filling offered remarkable increase of bending resistance and enhanced the crashworthiness of the structure. It turned out to prevent the inward fold formation at the compression flange, resulted into the multiple propagating folds and increased the load carrying capacity.
전기전도도를 이용한 Al-Si-Cu-Mg 합금 폼의 기계적 압축 특성 평가
이창훈(Chang-Hun Lee),김엄기(Amkee Kim),하산(Md Anwarul Hasan),남승훈(Seung-Hoon Nahm),조성석(Seong-Seock Cho) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Electrical conductivity of Al-Si-Cu-Mg alloy foams of various density produced in powder metallurgical method has been measured using two probe electrical conductivity measurement method. Compressive mechanical properties such as elastic modulus and plastic plateau stress of foams were evaluated from electrical conductivity using power law relation and scaling laws of foam properties. Uni-axial compression test was also performed. Experimentally measured elastic modulus and plastic plateau stress were compared with the values evaluated from electrical conductivity. The computed values were in good agreement with the experimental result.
A Nanoindentation Based Study of Mechanical Properties of Al-Si-Cu-Mg Alloy Foam Cell Wall
Md Anwarul Hasan(하산),Amkee Kim(김엄기),Chang-Hun Lee(이창훈),Hak-Joo Lee(이학주),Soon-Gyu Ko(고순규),Seong-Seock Cho(조성석) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
Nanoindentation technique has been used to measure the mechanical properties of aluminium alloy foam cell walls. Al-Si-Cu-Mg alloy foams of different compositions and different cell morphologies were produced using powder metallurgical method. Cell morphology of the foam was controlled during production by varying foaming time and temperature. Mechanical properties such as hardness and Young's modulus were calculated using two different methods: a continuous stiffness measurement (CSM) and an unloading stiffness measurement (USM) method. Experimental results showed that hardness and Young's modulus of Al-5%(wt.)Si-4%Cu-4%Mg (544 alloy) precursor and foam walls are higher than those of Al-3%Si-2%Cu-2%Mg (322 alloy) precursor and foam walls. It was noticed that mechanical properties of cell wall are different from those of precursor materials.
조성석,구자명,김학동 대한금속재료학회(대한금속학회) 1988 대한금속·재료학회지 Vol.26 No.9
The magnetic properties and the structure of high silicon steel sheets (3wt%-6.5wt%Si) prepared by the twin roller-quenching method were investigated. The columnar grains about 5-7㎛ in diameter were observed in the as-prepared sheets and the columnar grains grew from the surface to the center part of the sheet. In the as-prepared sheet, the coercive force was 1.05 Oe for the 6.5 wt%Si-Fe sheet, and the average mag netic iron loss W_(15/50) and W_(10/50) of the sheets having the coercive force of 1.05 Oe was 1.50 W/㎏ and 0.46W/㎏ respectively.
쌍롤법으로 제조한 고규소강판의 자기적 특성에 미치는 Si 함량의 영향
조성석,천병선,구자명 대한금속재료학회(대한금속학회) 1989 대한금속·재료학회지 Vol.27 No.2
The magnetic properties and microstructures of 0.3㎜ thick high Si-Fe alloys sheets made by the twin roll process were studied after annealing the sheets at 1100℃ for 60 minutes in the vacuum atmosphere of 10^(-4) Torr. The microstructure of 6.5 wt%Si-Fe alloy showed the DO₃precipitates in the B₂matrix. When the specimens were heated at a constant rate of 2℃/min, the electrical resistivities of 3, 4, 5 and 6wt%Si alloys increased in the temperature range between 330℃ and 750℃ in comparison to those of the as quenched state. On the contrary, the resistivity of 6.5 wt%Si alloy decreased in the temperature range between 350℃ and 550℃. The coercive force was 0.51 Oe for the 6.5 wt%Si-Fe alloy and the AC core loss W_(15/50) and W_(10/50) were 0.69 w/㎏ and 0.30w/㎏ respectively.
단롤법으로 제작한 6.5% Si-Fe 합금의 연자기적 특성
조성석,김택기,김학동,조용수 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.5
Soft magnetic properties of 6.5wt% Si-Fe alloy prepared by single-roll quenching technique have been studied. As surface speed of roll decreases columnar cells are formed perpendicular to ribbon surface and size of the cells becomes coarse. Thickness of sample decreases with increasing surface speed of roll. Experimental equation of thickness versus surface speed of roll may be written as D=S^(-(0.5∼0.6)), Coercive force and power loss measured at 60㎐ increase with increasing surface speed of roll. However, power loss measured at high frequencies, i.e. above 100㎐, is smaller than that at 60㎐, when surface speed of roll increases.
Ni基 超合金 Waspaloy의 再結晶에 미치는 初期 r' 크기의 영향(1)
조성석 충남대학교 공업교육연구소 1984 論文集 Vol.7 No.1
The effects of initial r'-size on the recrystallization behaviour of waspaloy have been studied by transmission electron microscopy. The deformed structure of I hour -aged specimen has more homogeneous and fine intersecting slip lines than that of 24 hour-aged specimen. These lead to the increase in sites of nucleation and the growth rate of the recrystallization front. Bypassing of migrating front due to high deformation accelerates the recrystallization of Waspaloy.