• Journal of Mechanical Science and Technology
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• 제17권6호
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• pp.787-795
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• 2003

Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions such as seismic loading are required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar (SHPB) technique with a special experimental apparatus can be used to obtain the material behavior under high strain rate loading conditions. In this paper, dynamic deformation behaviors of the aluminum alloys such as A12024-T4, A1606 IT-6 and A17075-T6 under both high strain rate compressive and tensile loading conditions are determined using the SHPB technique.

• 한국정밀공학회지
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• 제20권1호
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• pp.196-204
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• 2003

Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions such as seismic loading are required to provide appropriate safety assessment to these mechanical structures. The split Hopkinson Pressure Bar (SHPB) technique with a special experimental apparatus can be used to obtain the material behavior under high strain rate loading conditions. In this paper, dynamic deformation behaviors of the aluminum alloys such as A12024-T4, A16061-T6, and A17075-T6 under both high strain rate compressive and tensile loading conditions are determined using the SHPB technique.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 추계학술대회 논문집
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• pp.136-138
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• 2005

The responses of nanocrystalline aluminum powder of different grain sizes, was modeled Using, Khan, Huang, and Liang (KHL) viscoplastic model including hi-linear Hall-Petch type, based on experimental measurements. Correlation of strain-rate-dependent stress responses for different grain sizes were in good agreement with the experimental results.

• 월간포장계
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• 통권273호
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• pp.63-71
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• 2016

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.378-381
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• 2008

The buckling behavior of cylindrical shape-memory alloy and aluminum tube is investigated at room temperature using a split Hopkinson pressure bar and an Instron hydraulic machine with a specially designed recording system. The shape-memory alloy at superelastic property regime buckles gradually in quasi-static loading, and fully recovers upon unloading. However, the buckling of aluminum tube is sudden and catastrophic, and shows permanent deformation. This gradual buckling of shape-memory alloy is associated with the forward and reverse transformation of stress-induced martensite and seems to have a profound effect on the unstable deformation of tube structures made from shape-memory alloy.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.268-273
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• 2000

Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions are required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique, a special experimental apparatus, can be used to obtain the material behavior under high strain rate loading condition. In this paper, dynamic deformation behaviors of the aluminum alloys, Al2024-T4, Al6061-T6 and Al7075-T6, under high strain rate compressive and tensile loading are determined using SHPB technique.

• 소성∙가공
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• 제18권1호
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• pp.13-19
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• 2009

In the recent years, the production of light-weight products has become important because of increasing demands for the energy savings through weight reduction. Therefore the advanced manufacturing technology with Al alloy is continuously required in many industrial fields. Bending characteristics of Al rectangular tube with hollow and solid section has been analyzed by FE analysis in press bending with wing-die. Bending stress is affected by punch stroke and rotation of wing-die. There were different sectional sagging characteristics between the solid rectangle section and the hollow rectangle section.

• 소성∙가공
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• 제17권6호
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• pp.420-428
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• 2008

The effect of loading path changes on the strain and mechanical properties of a commercial pure aluminum was studied using flat rolling and groove rolling. Material during flat rolling undergoes a continuous monotonic compressive loading, while one during groove rolling experiences a series of cross compressive loading. Four-pass flat rolling and groove rolling experiment are designed such that the aluminum undergoes the same amount of the strain at each pass. The rolling experiment was performed at room temperatures. Specimens for tensile test are fabricated from the plate and bar rolled. In addition, the strain distribution for the plate and bar cold rolled specimens is also calculated by finite element method. The results reveal that differences of loading path attributed by monotonic loading(flat rolling) and cross loading(groove rolling) significantly influence the mechanical properties such as yield stress, ultimate tensile stress, strain hardening and elongation. It is clear that the different loading path can give raise to change the deformation history, although it is deformed with same amount of strain for same material.

• Computers and Concrete
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• 제7권5호
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• pp.403-419
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• 2010

The bond mechanism for reinforcing bars in concrete is equivalent to the normal contact and friction between the inclined ribs and the surrounding concrete. Based on the contact density model for the computation of shear transfer across cracks, an open-slip coupled model was developed for simulating three-dimensional bond behavior for reinforcing bars in concrete. A parameter study was performed and verified by simulating pull-out experiments of extremely different boundary conditions: short bar embedment with a huge concrete cover, extremely long bar embedment with a huge concrete cover, embedded aluminum bar and short bar embedded length with an insufficient concrete cover. The bar strain effect and splitting of the concrete cover on a local bond can be explained by finite element (FE) analysis. The analysis shows that the strain effect results from a large local slip and the splitting effect of a large opening of the interface. Finally, the sensitivity of rebar geometry was also checked by FE analysis and implies that the open-slip coupled model can be extended to the case of plain bar.

• 한국분말재료학회지
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• 제10권6호
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• pp.415-421
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• 2003

The study for producing the flake powders by milling of aluminum foil and gas atomized powders was carried out. The effects of lifter bars on the ball motions and milling of aluminum foils were also investigated. The aluminum foils were laminated each other, elongated, fragmented into small foils and finally formed into the flake powders during the dry ball-milling. The spherical atomized-powders were milled to coarse flake powders with high aspect ratio and then changed to fine flake powders with lower aspect ratio. Even though long times were required for making flake powders by milling of foils, the water covering areas of them were higher than those of powders milled using gas-atomized powders, suggesting aluminum foils were more plastically deformed by micro-forging. On the other hand, as the number of lifter bars increased, the necessary rotation speeds of milling jar for cascading mode and cataracting mode decreased drastically. It was possible to achieve same quality of milled flake powder by using the lifter bars under the lower milling speeds. The painting test showed that the appearance of painted surface was good and optimum content range of aluminum paste in car paint to maximize the degree of gloss was 3-5%.