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Mechanical Properties of Joints according to Welding Methods and Sensitivity Analysis of FSW's Welding Variables for A6005 Extruded Alloy of Rolling Stock (철도차량용 A6005 압출재의 용접방법에 따른 접합부 기계적 특성 및FSW 용접 변수의 민감도 분석)

  • Kim, Weon-Kyong;Won, Si-Tae;Goo, Byeong-Choon
    • Journal of the Korean Society for Railway
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    • 제13권2호
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    • pp.131-138
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    • 2010

  • Recently, extruded aluminium-alloy panels have been used in the car bodies in order to meet the needs for the speed-up and light-weight of the railway vehicles. Most of the car bodies were jointed by arc weldings, like GMAW (GasMetal Arc Welding) and GTAW (Gas Tungsten Arc Welding), but these weldings became fairly worse the mechanical properties of the junction than the base metal. Nowadays, FSW (Friction Stir Welding), which is superior to the arc weldings, has been applied in the railway vehicles. In this study, the mechanical properties of the joints in both FSW and GMAW for A6005 extruded aluminium-alloy sheets have discussed. In addition, the relationships between the welding conditions and the mechanical properties for the joint of FSW have analyzed through the sensitivity analysis. It can be concluded that the mechanical properties for the joint of FSW are better than those of GMAW and the welding speed is the most sensible welding condition in the process of FSW.

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A Case Study of PC-Culvert Construction with Foundation Plate (기초판 보강형 PC 암거의 시공사례 연구)

  • You, Jun;Choi, Chang-Ho
    • Journal of the Korean Geosynthetics Society
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    • 제10권2호
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    • pp.13-19
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    • 2011

  • Precast culvert system is generally constructed with a series of process such as excavation, ground mitigation, placement of culverts, anti-leakage packing between adjacent culverts, post-tensioning for PS strands and backfilling. In this process inappropriate ground mitigation often causes differential settlement and, correspondingly, makes water-leakage to be occurred between adjacent boxes. This study was performed to understand the behavioral characteristics of recently proposed precast foundation plate to support precast culvert system through on-site pilot construction. The gap between two adjacent culverts, increment of earth pressure at the bottom of culvert, vertical settlement of top of the culverts were monitored using various sensors. The monitoring results showed that the proposed foundation plate provides better culvert system in the points of less gap development, earth pressure and settlement at the adjacent of two culverts.

  • https://doi.org/10.12814/jkgss.2011.10.2.013 인용 PDF

Reflow properties of the lead-free solder with low melting temperature (저온 접합용 무연 솔더의 reflow 공정 특성)

  • Yu, A-Mi;Jang, Jae-Won;Kim, Mok-Soon;Lee, Jong-Hyun;Kim, Jun-Ki
    • Proceedings of the KWS Conference
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    • 대한용접접합학회 2009년 추계학술발표대회
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    • pp.76-76
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    • 2009

  • 눈부신 전자산업의 발달로 대부분의 전자제품이 다기능/경박단소화 되고 있어, 고밀도 실장 기술인 양면 표면실장과 고집적 패키징 기술인 패키지 적층 공정의 적용이 점차 확대되고 있다. 따라서 양면 표면실장 및 패키지 적층 공정에 사용되는 저온 접합용 무연 솔더 즉, $183^{\circ}C$(Sn-37Pb 공정 솔더 융점) 이하의 융점을 가지는 저온 무연 솔더에 대한 관심이 높아지고 있다. 한편, 미세피치 적용 분야에 있어 ACF/P를 이용한 COG 접속 분야 외에도 최근 저온 접합용 무연 솔더를 이용한 접속 분야가 각광을 받고 있다. 따라서, 접속피치 미세화에 대응하기 위해 스크린 인쇄성을 향상시킬 수 있는 저온 무연 솔더 paste 제조 및 공정 기술의 개발이 필요한 실정이다. 현재 대표적인 저온 무연 솔더 조성은 Sn-Bi계($138^{\circ}C$ 융점)와 Sn-In계($120^{\circ}C$ 융점)이다. 하지만, 이들 조성의 신뢰성 등에 있어 개선의 여지가 있으므로 이를 해결하기 위한 무연솔더 조성의 개발이 필요하다. 이와 같은 관점에서, 본 연구는 $137^{\circ}C$의 융점을 갖는 Sn-57.6Ag-0.4Ag 저온 무연 솔더 paste를 $217^{\circ}C$의 융점을 갖는 Sn-3.0Ag-0.5Cu 솔더 paste와 비교하여 인쇄성, reflow 특성, void inspection, 미세조직 관찰 및 underfill 적용 등의 실험을 실시하였다.

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Characteristic of Mechanical Clinching for Al5052 to High-Strength Steels (Al5052 합금소재와 고장력강판의 이종재료 클린칭 접합특성)

  • Lee, Chan-Joo;Lee, Sang-Kon;Lee, Seon-Bong;Kim, Byung-Min
    • Transactions of the Korean Society of Mechanical Engineers A
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    • 제34권8호
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    • pp.997-1006
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    • 2010

  • For manufacturing modern cars, so-called multi-materials, such as aluminum alloy with high-strength steels, are used. For obtaining such materials, a new joining method is required to achieve the multi-material design. Mechanical clinching is one of joining methods used to join the dissimilar materials. The objective of this study is to investigate the characteristics of mechanical clinching of Al5052 alloy to high-strength steels (SPFC440, 590, 780). Using FE-analysis and clinching experiment, the joinability of Al5052 alloy to high-strength steel is evaluated by geometrical shape of mechanical clinched joint, such as neck-thickness and undercut. Further, the joint strength is evaluated by performing a single-lap shear test. The upper high-strength steel SPFC780 was not clinched because of the necking of the upper sheet. The joint strength increased with increasing strength of the upper sheet. For the lower high-strength steel sheet, the joinability and joint strength decreased with increasing strength of the lower sheet.

  • https://doi.org/10.3795/KSME-A.2010.34.8.997 인용 PDF KSCI