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액체금속로 Y-구조물의 비탄성 열응력 해석 및 손상평가에 관한 유한요소해석
곽대영,임용택,김종범,이형연,유봉,Kwak, D.Y.,Im, Y.T.,Kim, J.B.,Lee, H.Y.,Yoo, B. 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.7
LMFBR(Liquid Metal Fast Breeder Reactor) vessel is operated under the high temperatures of 500-550.deg. C. Thus, transient thermal loads were severe enough to cause inelastic deformation due to creep-fatigue and plasticity. For reduction of such inelastic deformations, Y-piece structure in the form of a thermal sleeve is used in LMFBR vessel under repeated start-up, service and shut-down conditions. Therefore, a systematic method for inelastic analysis is needed for design of the Y-piece structure subjected to such loading conditions. In the present investigation, finite element analysis of heat transfer and inelastic thermal stress were carried out for the Y-piece structure in LMFBR vessel under service conditions. For such analysis, ABAQUS program was employed based on the elasto-plastic and Chaboche viscoplastic constitutive equations. Based on numerical data obtained from the analysis, creep-fatigue damage estimation according to ASME Code Case N-47 was made and compared to each other. Finally, it was found out that the numerical predictio of damage level due to creep based on Chaboche unified viscoplastic constitutive equation was relatively better compared to elasto-plastic constitutive formulation.
수정히스테리틱 Bi-Linear 면진베어린 모델을 사용한 지진응답감소
구경회,이재한,김종범,이형연,유봉,Koo, G.H.,Lee, J.H.,Kim, J.B.,Lee, H.Y.,Yoo, B. 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.1
In general, seismic isolators which are made of laminated rubber and shim plate have characteristics of complex hysteretic behavior. When shear deformation of the seismic isolator is small, the isolator hassimple hysteretic almost bi-linear behabior. But on large shear deformation hardening effects may occur. This paper proposes a moldeling method of the seimic isolator with modified hysteretic bi-linear model which can consider the hardening effects. From the results of the seismic analyses of the isolated system it is shown that the responses are singificantly reduced compared with those of the non-isolated system. The modified hysteretic bi-linear model of the isolator gives larger ZPA(zero period acceleration) than those of the simple hysteretic bi-linear model and the equivalunt spring-damper model.
액체금속로 고온배관의 미국 및 프랑스 설계지침을 따른 크리프-피로 손상평가
이형연(H.Y. Lee),김종범(J.B. Kim),유봉(B. Yoo) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3
In the present paper, the evaluation procedures of creep-fatigue damage for the high temperature piping system of the liquid metal reactor(LMR) according to the design guidelines of ASME section Ⅲ subsection NH of US and RCC-MR of France are presented. The assessment of design integrity for the secondary piping of KALIMER(Korea Advanced Liquid Metal Reactor) has been carried out, which showed the present design of the KALIMER secondary piping satisfied the allowable limits of the two design guidelines for the creep-fatigue damage. The creep load condition is the steady state(511℃) during 30 years design lifetime at the secondary piping circuit with plant capacity factor of 85%. The number of refueling during the design lifetime is 20. The differences in evaluation procedures of ASME-NH, RCC-MR RB-3600 for the primary piping and RC-3600 for the secondary piping are presented.