316L(N)스테인리스강의 Monkman-Grant 크리프 수명식의 적용성

김우곤,김대환,류우석,Kim, U-Gon,Kim, Dae-Hwan,Ryu, U-Seok 대한기계학회 2000 大韓機械學會論文集A Vol.24 No.9

Creep tests for type 316L(N) stainless steel were carried out using constant-load creep machines at 55$0^{\circ}C$, 575$^{\circ}C$ and $600^{\circ}C$. Material constants necessary to predict creep rupture time were obtained from the experimental creep data. And the applicability of Monkman-Grant(M-G) and modified M-G relationships was discussed. The log-log plot of M-G relationship between the rupture time($t_r$,) and the minimum creep rate ($ $\varepsilon$ _m$) was dependent on test temperatures. The slope of m was 1,05 at 55$0^{\circ}C$ and m was 1.30 at $600^{\circ}C$. On the other hand, the log-log plot of modified M-G relationship between $t_r/$\varepsilon$_r$, and $ $\varepsilon$ _m$ was independent on stresses and temperatures. That is, the slope of m' was approximately 1.35 in all the data. Thus, modified M-G relationship for creep life prediction could be utilized more reasonably than that of M-G relationship for type 316L(N) stainless steel. It was analyzed that the constant slopes regardless of temperatures or applied stresses in the modified relationship were due to an intergranular fracture grown by wedge-type cavities.

구조물의 수명 예축과 생명체의 상관관계에 대한 기하학적 고찰

전정범(Chun Jungbum) 한국정신과학학회 2014 한국정신과학회 학술대회 논문집 Vol.2014 No.10

구조물의 설계과정에 있어서 그의 항복곡선(P- δ 관계)은 강도와 파괴과정을 표편하며, 적분면적지는 파괘 ・방괴과정의 에너지를 설명해준다. 지진시의 큰 외력에 대하여 구조물의 기능을 발휘하기 위하여 지진피해를 입을 때마다 설계이론이 검토되여 설계기준이 개정되여 왔다. P-δ관계를 무차원화 할때 구조물의 종류와 크기에 상관 없이 그들의 변위・변형・파괴 과정을 서로 비교하며 특히 항복점을 통하여 해당 구조물의 보유 내력의 특징을 표편할 수 있다. 무차원화한 P- δ 관계는 기하학적으로 보면 항복점으로 특징짓는 함수로 근사할 수 있으며 함수로서는 황금나선 및 황금원을 선택할 수 있다. 자연 생물계에 있어서 황금나선 및 황금원을 비롯한 기하학적 함수로 근사 표현할 수 있는 현상들이 많이 있으나 인간 생체도 예외는 아니다. 이 논문은 구조물의 수명과 인간 생체 생명과의 상관관계를 기하학적으로 비교하며 공통점을 에너지론적으로 설명하고자 한다. The relationships between loads and displacements of structures are usually presented as P-δ curves. These curves are significantly usefull in the design of structures because they have particular quality related with the phenomenon of structures caused by outernal loads so especially as seismic loads. These curves are transrated to the none dimension functions in order to be compared among many different ones applied in designing of bridges surplying to road and train traffics, The graphs presented in the form of rectangurary are normallized in Hilbelt Spaces to approximate with mathematical functions so as golden circle. Many observations are usually presented as the rules prevailing the natural phenomenon as Fibonacci number and neo phythegorean theorem. The similar events are observed in the human living bodies as the organical phenomenon of other living things. In this paper especially the human lives are noticed to be compared with the structural life patterns presented as P-δ curves.

등시 응력-변형률 곡선을 이용한 대형가스터빈 블레이드 크리프 해석

정성용(Seongyong Jeong),이지문(Jimoon Lee),송진우(Jinwoo Song) 한국유체기계학회 2018 한국유체기계학회 학술대회 논문집 Vol.2018 No.11

코스틱스방법을 이용한 고온 크리프 파괴현상에 관한 연구

이억섭,홍성경 대한기계학회 1994 대한기계학회논문집 Vol.18 No.10

Caustics method has been applied successfully to determine the fracture parameters such as stress intensity factor and the J-integral for elastic and/or elastic-plastic stress field around the crack tip. For stress fields at the vicinity of crack tip in the creep domain, no experimental report concerning fracture mechanics parameters by using the caustics method has been published up to date. This study investigated creep behavior at the vicinity of crack tips at high temperature($175^{\circ}C$) and attempted to determine of proper fracture parameters for A1 5086 H24 specimens by using the caustics method. The results obtained from the limited experimental investigation are as follows; $J_{th}/J_{caus}$ is found to approach to 1 more rapidly than $K_{th}/K_{caus}$ does during incipient period(within 80 minutes). It is confirmed that experimental $K_{caus}$ approached to theoretical $K_{th}$ after 80 minutes by analyzing the ratio of $K_{th}$ to $K_{caus}$. Unlike the case of room temperature, it is confirmed experimentally that caustics diameter enlarged gradually even the distance between specimen and screen keeps constant. It showed that initial curve of the caustics was initially located in the plastic zone, but it grew out rapidly into the elastic zone for Al 5086 H24 at $175^{\circ}C$. It is confirmed that caustics is a function of time, temperature and distance between specimen and screen at high temperature.

Al합금의 크리프 파단수명에 관한 연구

배춘익,진도훈 한국기계기술학회 2011 한국기계기술학회지 Vol.13 No.4

Technological mode progress demands the use of materials at high temperature and pressure. Constant load creep tests have been carried out over the range of stresses at high temperatures. One of the most critical factors in considering such applications as the most critical one is the creep behavior. In order to investigate the creep behavior in this study, the stress exponents during creep were determined over the temperature range of 275℃ to 325℃ and the stress range of 36MPa to 72MPa. The applicability of modified Monkman-Grant relationship was also discussed.

단계성토 시 쌍곡선법의 개선된 해석방법

장석명,한희수 대한지질공학회 2022 지질공학 Vol.32 No.4

The purpose of settlement management when treating soft ground through preloading is to determine the amount of settlement, check the progression of consolidation, and compare the settlement with the target settlement amount. Of the various methods available for predicting settlement based on measured data, the hyperbolic method was used in this study to analyze the settlement behavior of soft ground considering the creep behavior resulting from staged fill. Two versions of the method were used: the existing hyperbolic method, and a modified hyperbolic method. The existing hyperbolic method predicts the settlement amount using data for the final settlement section only during soft ground treatment through staged fill, for which the coefficient of consolidation behavior (k) was computed to give a predicted final consolidation settlement amount of  = 1.05 cm. In comparison, using the modified method, a predicted final consolidation settlement of  = 0.50 cm is obtained by considering the data for each staged fill section. These results show that the modified method considering data from the staged settlement was more accurate than the existing method considering data only from the final settlement section. This modification to the hyperbolic method therefore represents an improvement in performance over the existing method. Preloading을 통한 연약지반처리를 할 때 침하관리는 침하량을 구하고 압밀의 진행상황을 확인하여 이를실측침하량과 비교 ‧ 분석하여 preloading의 방치기간, 철거시기, 여성토의 결정 등을 확인하는 것을 목적으로 한다. 침하관리를 위해서는 침하량을 예측해야 하는데 실측 data를 기반으로 침하량을 예측하는 방법중 쌍곡선법을 이용하여 단계성토로 인한 creep 거동을 고려한 연약지반 침하거동해석을 실시하였다. 기존의 쌍곡선법은 단계성토를 통한 연약지반처리 시 최종침하구간의 data만을 통해 침하량을 예측하였으나, 본 논문에서는 각 단계성토의 침하거동을 해석하고 단계성토에 따른 creep 거동 및 초기탄성침하를 고려하여 압밀거동계수(k)를 제시 및 최종압밀침하량을 예측하였다. 단계성토의 침하거동을 고려한 최종압밀침하량 예측결과, 기존의 최종침하구간의 data만 고려하여 예측한 최종압밀침하량( = 1.05 cm)보다각 단계성토별 α, β값을 통하여 예측한 최종압밀침하량( = 0.50 cm)이 더 정확한 값을 예측하였다.

변형 에너지를 이용한 크리프 한계응력강도(S<SUB>t</SUB>)의 결정

김우곤(Woo Gon Kim),이경용(Kyung Yong Lee),윤기봉(Kee Bong Yoon),류우석(Woo Seog Ryu) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.8

Creep stress intensity limit(S₁) value for 1% strain in 10? hr was determined using strain energy method based on the work done during creep. For this purpose, 1% creep strain tests for commercial type 316 (J316) and type 316LN (K316LN) stainless steels were conducted with various stress conditions at 550℃ or 593℃. The S₁ value of the K316LN stainless steel was 135 MPa at 550℃ and creep work was 87 KJ/m³. In order to identify reasonability of the strain energy method, the method of isochronus stress-strain curves(ISSC) for the J316 stainless steel was used comparatively. The S₁values for it showed good agreement between two methods. The strain energy method can be simply obtained using only three or four short-term 1% strain data without ISSC obtained by long-term creep data. Particularly, this method is useful in estimation of the stress intensity for new and emerging class of high-temperature materials where creep and tensile data for empirical extrapolation to design life is lacking.

P92 강의 장시간 크리프 강도 예측에 의한 Negligible Creep 곡선 도출

김우곤(Woo-Gon Kim),노영진(Young-Jin Noh),김선화(Seon-Hwa Kim),남기언(Ki-Ean Nam),이형연(Hyoung-Yeon Lee) 대한기계학회 2024 대한기계학회 춘추학술대회 Vol.2024 No.3

섬유로프 계류시스템의 크리프 효과가 부유체의 운동응답 및 계류선의 장력 변화에 미치는 영향에 관한 연구

박성민(Sung Min Park),이승재(Seung Jae Lee),강수원(Soo Won Kang) 대한조선학회 2017 大韓造船學會 論文集 Vol.54 No.2

Hastalloy-X 합금의 초고온 크리프 거동 예측

윤송남(Song-Nan Yin),김우곤(Woo-Gon Kim),정익희(Ik-Hee Jung),김용완(Yong-Wan Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5

The nickel-based Hastelloy X alloy is one of the candidate materials for structural components of the high temperature gas-cooled reactor (HTGR). Its creep data was obtained from the creep tests under several stress levels at 950℃, and using this data, the creep behavior was investigated by the θ-projection model. The proper fitting range was determined from the creep curves at any stress level because the θ<SUB>i</SUB>-parameters are dependent on a fitting strain range. A stress dependency for the B-parameters was established to accurately predict the creep curve of a low stress level. The time to 1%-low strains was predicted for various stress levels, and the ratios between the time to 1%-low strain and time to rupture were lower than 15%. Also, a predicted minimum creep rate revealed a good agreement with the experimental data.