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유한요소법을 이용한 용접열영향부의 균열진전 및 샤르피 흡수에너지 연구
장윤찬,이영석,Jang, Yun-Chan,Lee, Young-Seog 한국전산구조공학회 2009 한국전산구조공학회논문집 Vol.22 No.6
In this study, Charpy impact test and numerical studies were performed to examine the effects of failure behavior and energy absorption on the notch position. For this purpose, carbon steel plate(SA-516 Gr. 70) with thickness of 25mm usually used for pressure vessel was welded by SMAW(Shielded Metal-Arc Welding)method and specimens were fabricated from the welded plate. The Charpy impact tests were then performed with specimens having different notch positions varying within HAZ. A series of three-dimensional FE analysis which simulates the Charpy test and crack propagation are carried out as well. We divided HAZ into two, three and four regions to apply mechanical properties of HAZ to FE-analys. Results reveal that the absorbed energies during impact test depend significantly on the notch position. To obtain the results of reliability, HAZ should be divided into at least three regions. 본 논문은 샤르피 충격실험과 유한요소법를 이용하여 노치위치에 따른 파괴거동과 흡수에너지의 영향을 평가하였다. 본 연구자는 쉴드메탈아크 용접방법으로 두께가 25mm인 압력용기용강(SA-516 Gr. 70)을 용접하였고, 이 용접된 평판으로 샤르피 시편을 제작하였다. 샤르피 충격실험에서는 용접열영향부(HAZ)에서 노치위치가 다른 시편이 사용되었다. 그리고 본 연구자는 유한요소법을 이용하여 샤르피 충격실험에서의 균열진전을 모사하였다. 용접열영향부(HAZ)의 기계적 물성을 유한요소해석에 적용하기 위해 HAZ를 2개 영역, 3개 영역 그리고 4개 영역으로 나누었다. 본 연구결과에서는 샤르피 충격실험의 흡수에너지가 노치위치에 의존적이라는 것을 보여주었다. 또한 샤르피 용접시편에서 신뢰성 있는 유한요소해석 결과를 얻기 위해서는 용접열영향부를 적어도 3개 이상의 영역으로 나누어야 한다는 결과를 얻었다.
X-FEM을 이용한 원자력발전 소재의 J-R 산출 방법에 관한 연구
장윤찬(Jang Yun-Chan),정성호(Chung Sung-Ho),이재업(Lee Jae-Eob),김국철(Kim Kuk-Cheol),김형남(Kim Hyung-Nam) 대한기계학회 2013 대한기계학회 춘추학술대회 Vol.2013 No.12
Since the mid-1980s, the LBB design concept has been widely applied on nuclear high energy piping systems. For LBB design, material properties for stress-strain curves and J-R curves as a function of resistance to stable crack extension at service temperatures are needed. In this study, fracture toughness test and numerical studies were performed to calculate J-R curve characteristic of carbon steel and stainless steel for reactor coolant piping. Test temperature was 316 0C; same as the operating temperature of the piping system. A series of three-dimensional FE analysis which simulates the fracture toughness test and crack propagation are carried out as well. The calculated J-R curves were in good agreement with the test results.
장윤찬(Yun-Chan Jang),김익중(Ik-Joong Kim),유정수(Jung-Soo Yoo),김철만(Chul-Man Kim),백종현(Jong-Hyun Baek),김영표(Young-Pyo Kim),전법규(Bub-Gyu Jeon),장성진(Sung-Jin Chang) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
This paper provides the allowable limits of gas pipeline under cyclic loads using cyclic bending experiment. The effect of displacement on the allowable limits is analyzed. The pipe used in this study was API 5L X65 (508mm) material with thickness of 11.9 mm. The range of the displacement was 270 mm to 460 mm, the internal pressure was 8.0 MPa. A cyclic in-plane bending displacement was applied to the bend pipe until it leaked. The fatigue behavior of base metal of API 5L X65 was evaluated. For the bend pipe, the crack occurred at the intrados. The full scale experimental results and the design curve in ASME were compared.