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굽힘하중을 받는 분기관의 소성 붕괴 하중에 항복응력과 탄성계수의 비가 미치는 영향
정하주(Hajoo Chung),이국희(Kuk-Hee Lee),명만식(Man-Sik Myung),김윤재(Yun-Jae Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
This paper quantifies the effect of the yield strength-to-elastic modulus ratio on plastic collapse and instability loads for branch piping junctions under in-plane and out-of-plane bending. The finite element limit analyses based on elastic?perfectly-plastic materials using the large geometry change option provide plastic collapse loads (using the twice-elastic-slope method) and instability loads, and the plastic limit loads are determined from FE limit analyses using the small geometry change option. The plastic collapse loads and instability loads for branch pipe under bending are lower than limit loads. And the effect of internal pressure on plastic collapse and instability loads has been investigated. A wide range of parameters related to the bend geometry is considered.
CANDU형 원전 압력관에 존재하는 축방향 균열의 응력확대계수
이국희,오영진,박흥배,정한섭,정하주,김윤재,Lee, Kuk-Hee,Oh, Young-Jin,Park, Heung-Bae,Chung, Han-Sub,Chung, Ha-Joo,Kim, Yun-Jae 한국압력기기공학회 2011 한국압력기기공학회 논문집 Vol.7 No.1
CANDU reactor core is composed a few hundreds pressure tubes, which support and locate the nuclear fuels in the reactor. Each pressure tube provides pressure boundary and flow path of primary heat transport system in the core region. In order to guarantee the structural integrity of pressure tube flaws which can be found by in-service inspection, crack growth and fracture initiation assessment have to be performed. Stress intensity factors are important and basic information for structural integrity assessment of planar and laminar flaws (e. g. crack). This paper reviews and confirms the stress intensity factor of axial crack, proposed in CSA N285.8-05, which is an fitness-for-service evaluation code for pressure tubes in CANDU nuclear reactors. The stress intensity factors in CSA N285.8-05 were compared with stress intensity factors calculated by three methods (finite element results, API 579-1/ASME FFS-1 2007 Fitness-For-Service and ASME Boiler and Pressure Vessel Code Section XI). The effects of Poisson's ratio and anisotropic elastic modulus on stress intensity factors were also discussed.
제진호(Jin Ho Je),이국희(Kuk Hee Lee),정하주(Ha Joo Chung),김종성(Jong Sung Kim),김윤재(Yun Jae Kim) 대한기계학회 2010 大韓機械學會論文集A Vol.34 No.11
캐나다형 중수로에서 피더관은 가동 중에 유동 가속 부식에 의해 감육이 발생한다. 피더관에 감육이 발생하면 배관 건전성이 떨어진다. 본 논문은 원형 감육이 발생한 피더관에서의 기기신뢰성 평가를 위한 한계 하중을 연구하였다. 유한요소 해석을 통하여 면내 굽힘 하중과 내압을 받는 경우에 대하여 연구하였다. 재료는 대변형 효과를 고려하고 탄성-완전소성 재료로 가정하였다. 원형 감육이 발생한 피더관에 대하여 내압과 닫힘 방향, 열림 방향 굽힘 하중에 대하여 한계하중해를 제시하였다. Flow Accelerated Corrosion (FAC) occurring during in-service conditions results in localized wall-thinning in the feeder pipes of CANDU. The wall-thinning of the feeder pipes is the main degradation mechanisms affecting the integrity of piping systems. In this paper, we assess the integrity of wall-thinned feeder pipes by limit load analysis. The limit loads for wall-thinning feeder pipes subjected to in-plane bending and internal pressure were determined on the basis of finte element limit analyses. The limit loads are determined from the results of limit analyses of elasticperfectly-plastic materials using the large geometry change. Closed-form approximations of limit load solutions for wall-thinning feeder pipes subjected to in-plane bending and pressure are proposed.
제진호(Je Jin-Ho),이국희(Lee Kuk-Hee),정하주(Chung Ha-Joo),김주희(Kim Ju-Hee),한재준(Han Jae-Jun),김윤재(Kim Yun-Jae) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Flow Accelerated Corrosion (FAC) during inservice conditions produces local wall-thinning in the feeder pipes of CANDU. The Wall-thinning in the feeder pipes is main degradation mechanisms affecting the integrity of piping systems. This paper discusses the integrity assessment of wall-thinned feeder pipes using limit load analysis. Based on finite element limit analyses, this paper compare limit loads for wall-thinning feeder pipes under combined bending and internal pressure with proposed limit loads. The limit loads are determined from limit analyses based on rectangular wall-thinning and elastic-perfectly-plastic materials using the large geometry change.