• 제목/요약/키워드: Ultra thick plate

검색결과 17건 처리시간 0.022초

극후판 EH40 TMCP강재 Tandem EGW 용접부의 잔류응력 해석 (Numerical Analysis of Welding Residual Stresses for Ultra-Thick Plate of EH40 Steel Joined by Tandem EGW)

  • 황세윤;이장현;김병종;양용식
    • 대한조선학회논문집
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    • 제47권6호
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    • pp.821-830
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    • 2010
  • Deck plates and hatch coming of large container carrier and offshore structures are joined by ultra-thick plates whose thickness is more than 60mm. Traditionally FCAW has been used to join the thick plates in butt joint. However, FCAW has been replaced with EGW since the welding efficiency of EGW is higher than that of FCAW. Tandem EGW using two electrodes has been applied to vertical position welding by several shipyards. EGW requires one or two layers of bead whereas FCAW requires more than 20 layers of weld bead in thick welding. However, high welding residual stresses are generated by EGW since it uses higher heat input than FCAW. In the present study, a finite element model is suggested to predict the residual stresses induced by the tandem EGW. Butt specimen of EH40 TMCP shipbuilding steel plates vertical welding was modeled by a three-dimensional model. Residual stresses were measured by X-ray diffraction method and to verify the numerical result. The results show a good agreement with experimental result.

극후판 Box-Column의 Lamellar 균열 감수성 평가 (Sensitivity Appraisal for Lamellar Tearing of Box-Column of Ultra Thick Plate)

  • 노찬승;박창수;김흥주;방한서;이창우
    • 한국해양공학회지
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    • 제17권4호
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    • pp.31-36
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    • 2003
  • In case of this thick rolling-steel for a multistory building, a large oil-drilling structure, a large vessel, a bridge and so on, Lamella Tearing around the welded joint zone is the most serious problems. In order to prevent Lamella Tearing, not only is choice of material important, but also the comprehensive investigation for the structural design and the construction. The Lamella Tearing that is a staircase-shape occurs due to the contraction stress to the thickness direction of the plate and has the character that the cracks progress along the elongated inclusion by rolling. In general, because cracks occur at the heat affected zone and around HAZ, it is necessary to establish the safety and the confidence of the welded structure to restrain the welding defect such as Lamella Tearing. The mechanical approaches are the easier and more economical than the approaches of the material and the construction method. In addition, the appropriate welding profile and the optimum welding condition contribute toward the improvement of the productivity and influence on the standardization of the manufacturing technology.

프레스 공정을 이용한 미세 골판형 내부구조재 제작에 관한 연구 (A Study on Fabrication of Inner Structure Plate with Micro Corrugated Using Press Forming)

  • 최두선;제태진;김형종;김보환;허병우;성대용
    • 한국정밀공학회지
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    • 제23권9호
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    • pp.61-67
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    • 2006
  • Sandwich structures, which are composed of a thick core between two faces, are commonly used in many engineering applications because they combine high stiffness and strength with low weight. Accordingly, the usage of sandwich structure is very widely applied to the aircraft, the automobile and marine industry, etc., because of these advantages. In this paper, we have investigated the buckling protection of an inner structure plate and the useful corrugated configuration for contact, and the fabrication method of the inner structure plate for large area using the continuous molding process. Also, we have guaranteed the accuracy of the molding process through the micro corrugated mold fabrication and secured the accuracy and analyzed aspect properties of the inner structure plate fabricated for a large area using the partial mold process. We have compared molding simulation according to the aspect thickness of the corrugated configuration with the molding experiment results.

EH40과 API2W강재의 극 후판재 다층 FCAW 버트 접합부 잔류응력해석 (Numerical Analysis of Welding Residual Stresses for Ultra-thick Plate of EH40 TM and API 2W Gr.50 Steel Joined by Flux Core Arc Welding)

  • 황세윤;이장현;양용식;이성제;김병종
    • Journal of Welding and Joining
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    • 제28권3호
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    • pp.65-72
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    • 2010
  • Some structural members of large-scale marine vessels such as large-scale offshore structures and very large container ships are assembled by very thick plates of which thickness exceeds 60mm. Also, high-tensile steels have been selected to meet the required structural strength and fatigue strength. Generally, multi-pass welding method such as FCA(Flux-Core Arc) welding has been used to join the thick plates. Considering the welding residual stresses, fatigue strength of the welded joints of thick plates should be assured since the residual stress influences the fatigue strength. This paper presents a numerical procedure to investigate the residual stress of structure joined by multi-pass FCA welding so that it can be incorporated into the fatigue strength assessment considering the effect of welding residual stress. The residual stress distribution is also measured by X-Ray diffraction method. The residual stress obtained by the computational model also has been compared with that of experiment. The results of FEA are in very good agreement with the experimental measurements.

디지털 소자용 방열판 제작을 위한 초고속 금속필름 증착장치 및 공정기술 개발 (The development of ultra high-speed metal film deposition system and process technology for a heat sink in digital devices)

  • 윤효은;안성준;한동환;안승준
    • 한국산학기술학회논문지
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    • 제18권7호
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    • pp.17-25
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    • 2017
  • 최근에 LED나 OLED와 같은 조명용 소자의 온도 상승에 따른 문제점을 개선하기 위하여 전기 도금 방법을 사용하여 제작한 두께가 두꺼운 금속 필름을 heat sink로 사용하고 있다. Cu 필름과 같은 두꺼운 금속 필름은 습식 방법인 전기 도금으로 제작하여 주로 소자의 방열판으로 사용되어 왔으나 건식의 증착 방법을 이용한 수 백 ${\mu}m$의 Cu 금속 필름에 대한 필요성이 요구되고 있다. 본 연구에서 설계 제작된 유도 가열 방식의 Cu 필름 증착 장비는 가열부가 세라믹 도가니 히터 부분과 세라믹 도가니 부분으로 분리된 이중 구조의 heating 방식을 채택하여 열 손실을 최소화 하고 보온 효과를 극대화시켰다. 또한 유도 가열 방식으로 초고속의 필름 증착 속도를 구현하였다. 그리고 열전도도가 높고 안정적인 두꺼운 Cu 필름 증착기술을 확보하고 최적화 하여 $1000{\AA}/s$의 증착율로 $100{\mu}m$의 필름을 증착 하였으며 ~2.0% 이내의 두께 균일도를 얻었다.

기판온도에 따른 Co-22%Cr 합금박막의자가정렬형 나노구조 (Self-Organized Nano Structure in Co-22% Cr Alloy Thin Films with Substrate Temperatures)

  • 송오성;이영민
    • 한국표면공학회지
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    • 제34권6호
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    • pp.531-536
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    • 2001
  • Co-22 %Cr alloy films are promising for high-density perpendicular magnetic recording media with their perpendicular anisotropy and large coercivity of 3000 Oe. We observed that a self organized nano structure (SONS) of fine ferromagnetic Co-enriched phase and paramagnetic Cr-enriched phase appears inside the grain of Co-Cr magnetic alloy thin films at the elevated substrate temperature after do-sputtering. The periodic fine Co-enriched phase and Cr-enriched phase is the plate shape of 80 (equation omitted)-wide and 1000 (equation omitted)-long. Cr-enriched phases are located at the center of grains. We prepared 5000 (equation omitted) -thick Co-22 %Cr films on polyimide substrate with varying substrate temperature of $ 30^{\circ}C$, $ 150^{\circ}C$ ,200 $^{\circ}C$, $300^{\circ}C$, and $400^{\circ}C$, respectively. A transmission electron microscope equipped with energy dispersive X-ray analyzer is employed to observe the microstructure of each samples after Co-enri-ched phase are etched selectively. The self organized nano structure of Co-enriched and Cr-enriched lamellar is observed above the substrate temperture of $150^{\circ}C$. No compositional change is observed with substrate temperature. The compositional phase separation in self organized structure becomes clear as the substrate temperature increases. Our results implies that the self organized nano structure in Co-22 %Cr film is ideal for ultra high density recording media by recording selectively on Co-enri-ohed phase.

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TiO2 광촉매와 UV LED를 이용한 접촉연소식 수소센서 (Catalytic combustion type hydrogen gas sensor using TiO2 and UV LED)

  • 홍대웅;한치환;한상도;곽지혜;이상렬
    • 센서학회지
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    • 제16권1호
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    • pp.7-10
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    • 2007
  • A thick film catalytic gas sensors which can be operated at $142^{\circ}C$ in presence of ultra violet-light emitting diode has been developed to measure hydrogen concentration in 0-5 % range. The sensing material as a combustion catalyst consists of $TiO_{2}$ (5 wt%) and Pd/Pt (20 wt%) supported on $Al_{2}O_{3}$ powder and the reference material to compensate the heat capacity of it in a bridge circuit was an catalyst free $Al_{2}O_{3}$ powder. Platinum heater and sensor materials were formed on the alumina plate by screen printing method and heat treatment. The effect of UV radiation in the presence of photo catalyst $TiO_{2}$ on the sensor sensitivity, response and recovery time has been investigated. The reduction of operating temperature from $192^{\circ}C$ to $142^{\circ}C$ for hydrogen gas sensing property in presence of UV radiation is attributed to the hydroxy radical and superoxide which was formed at the surface of $TiO_{2}$ under UV radiation.