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배준우(Joon Woo Bae),이춘열(Choon Yeol Lee),채영석(Young Suck Chai) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.10
Fretting, which is a special type of wear, is defined as small amplitude relative motion along the contacting interface between two materials. The structural integrity of steam generators in nuclear power plants is very much dependent up on the fretting wear characteristics of Inconel 690 U-tubes. A finite element model that can simulate fretting wear was developed in this study in order to investigate the behavior of the phenomenon quantitatively. Two-dimensional and three-dimensional finite element analyses were adopted to investigate the fretting wear problems. Two-dimensional finite element analyses for elastic contact wear problems were performed to demonstrate the feasibility of the finite element method to the fretting wear problems in consideration of frictional contact. A numerical example which has existing solutions was treated. By introducing a control parameter s, which scaled up the wear constant and scaled down the cycle numbers, the algorithm was shown to greatly reduce the time required for the analysis. In the wear model, the work rate model was adopted. The two-dimensional solutions of the study are in good agreement with the previous results by Stromberg. The actual tube-to-tube fretting wear tests in the steam generator were simulated in the three-dimensional finite element analysis. Normal contact pressures and wear depth along the contact surface were plotted under the different values of wear parameters and a number of cycles.
평편족의 치료로 이용한 관절고정술시 스프링인대군 (spring ligament complex)에서 strain의 변화
이경태,배준우,Lee, Kyung-Tai,Bae, Joon-Woo 대한족부족관절학회 1997 대한족부족관절학회지 Vol.1 No.1
It was well known that arthrodesis of the tarsal joint is an exellent procedure to correct the flatfoot deformity for relieving pain. Recently, concept of the selective tarsal joint fusion instead of the triple fusion was developedto preserve the joint motion. To investigate and compare the effect of the each different tarsal fusion, we measured the strain at the spring ligament, medial roof of the medial longitudianl arch. Five fresh frozen cadevar foot specimens, with distal half of the tibia were utilized. The superomedial portion of the spring ligament complex was dissected from the origin to the insertion. For each specimen, a calibrated open liquid metal strain guage was secured along the length of the superomedial portion. Under the specially devised test rig, measurement of the strain was taken at each test condition from the tare weight 18.2 lb followed by 38.2 lb., 82.2 lb and a maximum loads of 134.6 lb. : 1) unfused condition, 2) isolated subtalar fusion 3) isolated talonavicular fusion 4) combined subtalar and talonavicular fusion 5) triple fusion. Statistics showed that siginificant reduction in strain following the triple fusion, and from the subtalar fusion to triple fusion.
유한요소법을 이용한 조건에 따른 마모 영역별 2차원 프레팅 마모 해석
우종관(Jong Kwan Woo),배준우(Joon Woo Bae),이춘열(Choon Yeol Lee),채영석(Young Suck Chai) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.3
In nuclear power plant, fretting wear, caused by flow induced vibration (FIV), can make a serious problem in a U-tube bundle in steam generator. In this study, finite element analysis of the fretting wear on the secondary side of the steam generator was investigated which arises between U-tubes and their supports or foreign objects. Using finite element method, two-dimensional models with cylindrical or plate supports were adopted to investigate the fretting wear problems. As boundary conditions, various combinations of loads are applied to verify different fretting mechanisms, such as stick only, stick-slip and gross slip wear. For this purpose, four different load conditions are considered and in the finite element analysis, ABAQUS are used with the program which is developed to calculate wear depth and modify input files at each cycle. As a result, regions for each wear mechanism are found and fretting wear map is constructed, which can be used as a reference or criterion for fretting wear experiments.
이춘열(Choon Yeol Lee),배준우(Joon Woo Bae),윤덕용(Deok Yong Yun),배광훈(Kwang Hoon Bae),채영석(Young Suck Chai) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
In nuclear power plant, fretting wear caused by flow induced vibration (FIV) accompanied with sliding and impact loading can make a serious problem between U-tubes and supports which are located in steam generators. In order to simulate the impact/sliding fretting wear, a fretting wear simulator was developed, which can perform classical fretting wear and impact/sliding fretting wear experiments under high temperature and high pressure environment. Before the complete analyses of impact and sliding fretting wear, finite element models for the dynamic characteristics by impact forces in steam generators are developed in this study. After verification of the finite element models in comparison with existing solutions, dynamic analysis of two dimensional tube-to-plate model is performed. Finally, based on the results by finite element analyses, impact velocity, kinetic energy and impact energy are calculated, which will be correlated with the wear amount measured from the experiments.
고온 고압 환경에서 인코넬 690 재료의 프레팅 마모 특성에 관한 실험적 연구
이춘열(Coon Yeol Lee),이주석(Ju Suck Lee),배준우(Joon Woo Bae) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.6
증기 발생기 내부의 U-tube와 지지 구조간의 충격에 의하여 발생하는 프레팅 마모는 원자력 발전소 안전성에 영향을 미치게 된다. 증기발생기의 신뢰성을 향상시키기 위하여 이러한 프레팅 마모 현상을 평가하는 것이 필요하며, 본 연구는 프레팅 마모현상을 정성적, 정량적으로 규명하기 위하여 증기발생기의 실제 상황과 같은 조건의 온도와 압력하에서 실험을 수행하였다. 다양한 실험조건에 대하여 기본적인 실험을 수행하였으며 일률과 마모량의 관계를 온도에 따라 구하였다. 90℃, 200℃, 340℃ 각각의 온도에서의 마모상수는 9.051x10-16 Pa-1, 3.009x10<SUP>-15</SUP> Pa<SUP>-1</SUP>, 2.235x10-15 Pa-1 로 구해졌으며 특히 저온 수중상태의 마모상수는 물의 점도의 영향으로 상온 공기중의 값보다 작은 것으로 나타났다. In a nuclear power plant, fretting wear due to impact motion between U-tubes and support structures located in steam generators can cause serious problems. In order to guarantee the reliability of the steam generator, the damage due to fretting wear should be thoroughly investigated. The purpose of this study is to elucidate the fretting wear mechanism qualitatively and quantitatively. Hence, fretting wear simulation is performed for the environments to which the actual steam generators in nuclear power plants are exposed. Initial experimental results are obtained for various experimental parameters, and the effect of the work rate and temperature on fretting wear is evaluated. In water, the wear coefficients for 90℃, 200℃, and 340℃ are found to be 9.051×10<SUP>-16</SUP> Pa<SUP>-1</SUP>, 3.009×10<SUP>-15</SUP> Pa<SUP>-1</SUP>, and 2.235×10<SUP>-1</SUP>5 Pa<SUP>-1</SUP>, respectively. It is also found that the wear coefficient at room temperature is larger than that at low temperature in water because of the dynamic viscosity of water.
고온 고압 환경에서 인코넬 690 재료의 프레팅 마모 특성에 관한 실험적 연구
이춘열(Choon Yeol Lee),이주석(Ju Suck Lee),배준우(Joon Woo Bae) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.10
In nuclear power plant, fretting wear can make serious problems caused by impact motion between U-tubes and support structures located in steam generators. In order to guarantee the reliability of the steam generator, the damage due to the fretting wear should be throughly investigated. The purpose of this study is to elucidate fretting wear mechanism qualitatively and quantitatively. Hence, fretting wear simulation is performed according to the environment to which the actual steam generators in nuclear power plant are exposed. Initial experimental results are obtained for various experimental parameters and the effect of work rate and temperature on fretting wear is evaluated.