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고유변형도 기반 등가 변형도법을 적용한 마찰교반용접 알루미늄 합금의 용접 해석
강성욱,문형석,김재웅,장창두,장범선 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.11
최근 환경보호와 에너지절감에 대한 관심이 높아짐에 따라 선박, 항공기, 철도차량, 자동차 등 수송기기의 경량화를 위한 기술 개발이 활발히 진행되고 있으며 이를 위해 알루미늄, 마그네슘 등 경량합금 부재의 적용이 빠른 속도로 확대되고 있다. 선박은 잔류응력에 대한 유리함과 경량화등을 목적으로 알루미늄 합금을 선박에 적용하고 있다. 알루미늄 합금 구조체는 열영향부가 피로, 충격에 약하다. 이에 대한 대책이 요구되는 상황에서 기존 용접방식에 비해 입열 량이 적고 용접봉, 보호 가스 등이 필요 없는 친환경적인 마찰 교반 용접(Friction Stir Welding, FSW)이라는 비용융 고상접합공정이 1991년 영국 TWI에서 개발되었다. 일반적으로 마찰 교반 용접은 열영향부가 크지 않기 때문에 용접 변형 및 잔류응력이 작다. 본 논문에서는 마찰 교반 용접을 적용하는 알루미늄 합금에 대해 고유변형도 기반 등가 변형도법을 이용하여 용접 변형뿐만 아니라 용접 잔류응력을 해석 하려한다.
이주성(Joo-Sung Lee),이진태(Jin-Tae Lee) 한국해양공학회 2010 韓國海洋工學會誌 Vol.24 No.2
A simplified finite element analysis has been used to predict the weld-induced deformation to bead-an-plate welding of steel plates having curvatures in the welding direction. In this study the equivalent loading method based an inherent strain was used to investigate the effect of longitudinal curvature an the weld-induced deformation of curved plates. Equivalent loads were derived from the inherent strain distribution around the weld line, and the loads were used far linear finite element analyses. These kinds of numerical simulations can, of course, be performed by using the rigorous thermal-elastic-plastic analysis method. This approach is not, however, practical far use in weld-induced deformation analysis of large and complex structures, such as ship structures, in view of computing time and cost. The present equivalent load approach has been applied to several plate models having curvatures in the welding direction, and the results are compared with those obtained by thermal-elastic-plastic analysis and also with those obtained by the other simplified method found in reference. As far as the present results are concerned, the weld-induced deformation of curved plates can be accurately predicted by the method presented in this paper.
등가 열변형률법을 이용한 박판 및 파이프의 용접변형 예측에 관한 연구
김용래,양영수,이창훈,김재웅 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.6
This study aims to compare and analyze longitudinal bending and angular distortion due to bead on plate welding by conducting experiments and numerical analyses. TIG-welding experiments were conducted on a steel plate and pipe with a thickness of 2 mm. The numerical analysis was conducted by an FE software MSC.marc. Further, the results of numerical analyses obtained via the thermo-elastic-plastic method and equivalent thermal strain method were compared with the experimental ones. Based on the comparisons, we investigated an efficient analysis method for welding deformation. 본 논문의 목적은 용접 시 발생되는 종굽힘과 각변형에 대하여 실험과 두 가지 수치해석 방법을 통해 비교 및 분석하는 것이다. 실험은 2 mm 두께의 평판재와 파이프에 대해 TIG 용접을 실시하였으며, 수치해석은 MSC. marc 상용프로그램을 통해 열탄소성 해석법(TEP)과 등가 열변형률 해석법(ETS)을 적용하여 실험 결과와 비교하였다. 이를 바탕으로 보다 효율적인 용접변형 해석 방안에 대하여 고찰하였다.
고유 변형도법과 리메슁 기술을 접목한 블록의 역세팅 형상 예측기술
현충민(Chung-Min Hyun),최한석(Han-Suk Choi),박창우(Chang-Woo Park),김성훈(Sung-Hoon Kim) 한국해양공학회 2017 韓國海洋工學會誌 Vol.31 No.6
In order to reduce the cost of corrections and time needed for the block assembly process, the reverse setting method is applied for a back-heated block to neutralize deck deformation. The proper reverse setting shape for a back-heated block to correct deformation improved the deck flatness, but an excessive amount of reverse setting could inversely affect the flatness of the block. A prediction method was developed for the proper reverse setting shape using a back-heated block, considering the complex geometry of blocks, thickness of the deck plate, and thermal loading conditions such as welding and back-heating. The prediction method was developed by combining the re-meshing technique and inherent strain-based deformation analysis using the finite element method. Because the flatness deviation was decreased until the lower critical point and thereafter it tended to increase again, the optimum value for which the flatness was the best case was selected by repeatedly calculating the predefined reverse setting values. Based on this analysis and the study of the back-heating deformation of large assembly blocks, including the reverse setting shape, the mechanism for selecting the optimum reverse setting value was identified. The developed method was applied to the actual blocks of a ship, and it was confirmed that the flatness of the block was improved. It is concluded that the developed prediction method can be used to predict the optimum reverse setting shape value of a ship’s block, which will reduce the cost of corrections in the construction stage.
김호경(HO-KYUNG KIM),장창두(CHANG-DOO JANG) 한국해양공학회 2003 韓國海洋工學會誌 Vol.17 No.1
In this study, we developed an analysis method of plate forming by induction heating, verifying the effectiveness of the present method through a series of experiments. The phenomena of the induction heating involves a 3D transient problem, coupled with electromagnetic, heat transfer, and elastoplastic large deformation analyses. To solve the problem, we present an appropriate model and an integrated system. Using the present analysis model, we can estimate the plate deformation in heating without experiments and simulate the plate bending process of induction heating.