• 소성∙가공
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• 제12권3호
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• pp.184-193
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• 2003

• 한국재료학회지
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• 제29권10호
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• pp.647-655
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• 2019

In order to analyze the effect of hot asymmetric rolling on the microstructure and texture of aluminum alloy and to investigate the effect of the texture on the formability and plastic anisotropy of aluminum alloy, aluminum 6061 alloy is asymmetrically rolled at room temperature, $200^{\circ}C$, $350^{\circ}C$, and $500^{\circ}C$, and the results are compared with symmetrically rolled results. In the case of asymmetric rolling, the equivalent strain (${\varepsilon}_{eq}$) is greatest in the upper roll part where the rotational speed of the roll is high and increases with increasing rolling temperature. The increase rate of the mean misorientation angle with increasing temperature is larger than that during symmetrical rolling, and dynamic recrystallization occurs the most when asymmetrical rolling is performed at $500^{\circ}C$. In the case of hot symmetric rolling, the {001}<110> rotated cube orientation mainly develops, but in the case of hot asymmetric rolling, the {111}<110> orientation develops along with the {001}<100> cube orientation. The hot asymmetric rolling improves the formability (${\bar{r}}$) of the aluminum 6061 alloy to 0.9 and reduces the plastic anisotropy (${\Delta}r$) to near zero due to the {111}<110> shear orientation that develops by asymmetric rolling.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.57-66
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• 2006

AA5182-polypropylene sandwich sheet was manufactured, and the mechanical properties evaluation was executed in order to identify $L{\ddot{u}}ders$ band that causes fabrication process problem and especially surface roughness. To identify formability, deformation behavior, plastic strain ratio (R-value) and pole figure were measured, and texture analysis was performed. In the case of sandwich sheet, the unstable deformation behavior has decreased. As well, for sandwich sheet, A1 skin could manage the most of load, and the elongation has improved about 45% more than that of A1 skin. The plastic strain ratio of A1 skin and sandwich panel, which indicates serration behavior, was obtained from instantaneous plastic strain ratio evaluation. Also, the planar anisotropy of sandwich sheet has decreased more than that of A1 skin. According to these results, the sandwich sheet produced lightening effect and could control unstable deformation characteristic, that is, surface roughness caused by $L{\ddot{u}}ders$ band. Furthermore, it was proved that the texture control of the rolling attachment of A1 skin is necessary to improve the formability of the sandwich panel.

• 소성∙가공
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• 제22권3호
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• pp.150-157
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• 2013

Fiber metal laminates (FMLs) are layered materials comprised of thin metal sheets and fiber reinforced plastic (FRP). This paper presents the numerical study of the formability enhancement of FMLs composed of an aluminum alloy and self-reinforced polypropylene (SRPP) composite. In this study, a numerical simulation based on finite element (FE) modeling is proposed to evaluate the formability of FMLs using ABAQUS/Explicit. The FE model, which included a single layer of solid and shell elements to model the blank, used discrete layers of the solid element with a contact model and shell elements with a friction based model for the aluminum alloy-composite interface conditions. This method allowed the description of each layer of FMLs and was able to simulate the interaction between the layers. It is noted through this research that the proposed numerical simulation described properly the formability enhancement of the FMLs and the simulation results showed good agreement with experimental results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.285-287
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• 2006

Ultra-fine grained and high hardened Al sheet was obtained by Equal channel angular pressing (ECAP). During this process the microstructure, the hardness and the texture of AA 1050 Al alloy sheet are changed by a severe shear deformation. The plastic strain ratio after the ECAP and subsequent heat-treatment condition has been investigated in this study. It was found that the average r-value of the ECAPed and subsequent heat-treated specimen was 1.7 times higher than those of the initial Al sheet. This could be attributed to the various texture formations through the ECAP and subsequent heat-treatment of AA 1050 Aluminum alloy sheet.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 제5회 박판성형 SYMPOSIUM
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• pp.88-91
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• 2006

Ultra-fine grained and high hardened Al sheet was obtained by Equal Channel Angular Pressing (ECAP). During this process the microstructure, the hardness and the texture of AA 1050 Al alloy sheet are changed by a severe shear deformation. The plastic strain ratio after the ECAP and subsequent heat-treatment condition was investigated in this study. It was found that the average r-value of the equal channel angular pressed and subsequent heat-treated specimen was 1.7 times higher than that of the initial Al sheet. This could be attributed to the various texture formations through the ECAP and subsequent heat-treatment of AA 1050 Aluminum alloy sheets.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
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• pp.171-173
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• 2005

To evaluate the applicability of dissimilar metal friction stir welding in automobile manufacturing process, friction stir welding trials were carried out for typical 5000 and 6000 series aluminum alloy sheets with 2mm thickness. The sound joints of A15052 and A16061-T6 alloys were successfully formed under a wide range of welding condition. Excellent weld ability has been obtained at a condition of rotating speed 2000rpm and travel speed 100mm/min, while a radiographic test also confirmed defect free joint for this condition. Through the Erichsen cup test, the plastic formability of the FSWelded joints was found to be about 83% of base metal.

• 소성∙가공
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• 제5권2호
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• pp.138-144
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• 1996

The differences of formability with maximum cup depth of drawn product and thickness strain distribution are compared for two kinds of blank shapes which are suggested optimum shape and conventional square shape. The suggested blank is determined by backward tracing technique of rigid-plastic FEM. The deeper cup without wrinkle and flange part could be obtained from the suggested blank shape however the cross sevtion sup from the square blank could not be kept smooth thickness strain distribution and defended those phenomena..

• 소성∙가공
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• 제21권2호
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• pp.113-118
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• 2012

Magnesium sheet alloys possess limited plastic formability at room temperature but their formability is substantially improved at elevated temperatures and optimum strain rates. In the present paper, three different types of failure criteria, namely, strain-based, stress-based, and work-based criteria, are compared for their applicability to warm press forming of magnesium sheet alloys. Warm deep-drawing experiments were conducted on AZ31 alloy sheet, and the results were used to assess the strength and weakness of the failure criteria.

• 소성∙가공
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• 제7권6호
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• pp.603-609
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• 1998

An aluminium sandwich sheet is the material fabricated by adhering two aluminum panels to one plastic core. When it has the same bending stiffness as an steel panel it is 65% lighter than steel panel and 30% lighter than aluminum panel. Therefore it is notified exclusively as good substitutive materials for steel body to improve fuel efficiency. An aluminium sandwich sheet, however, has a problem of the lower formability than steel in automotive application. In this paper we intend to develop application technologies of an aluminum sandwich sheet for auto body panels from selecting composed materials of aluminium sandwich sheets to fabricating prototype. We selected aluminium sandwich panels fabricated by Hoogovens company. Through formability tests we have designed the hood part on auto body panels and fabricated a mould and a prototype.