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외압이 작용하는 마모 실린더의 붕괴 압력 예측을 위한 한계하중 및 비선형 좌굴 해석
석태현(Tae-Hyeon Seok),노가람(Ga-Ram Rho),김동석(Dong-Seok Kim),강병현(Byoung-Hyun Kang),지민정(Min-Jung Ji),박승현(Seung-Hyun Park),허남수(Nam-Su Huh) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.4
원자로용 SGT(Steam Generator Tubes)와 같이 외압을 받는 실린더는 접촉 표면에서의 미세 진동 운동 등에 의해 마모가 발생할 수 있다[1]. 실린더는 마모 발생 전후로 좌굴 거동에 분명한 차이가 존재하므로[2] 구조적 건전성 평가가 필요하다. 이에 본 연구에서는 외압이 작용하는 마모 실린더의 선형 좌굴(linear buckling), 비선형 좌굴(non-linear buckling), 소성 붕괴(plastic collapse) 해석을 수행하여 붕괴압력을 평가하였다. 실린더 중심부에 마모 길이 및 깊이가 다른 다양한 마모 형상을 고려하였다. 실제로는 형상의 부정(imperfection)에 의해 임계압력이 저하되므로 선형 좌굴 해석의 결과를 정확한 좌굴압력으로 보기는 어렵다[3]. 따라서 소성 붕괴, 비선형 좌굴 해석으로 얻은 한계압력, 임계좌굴압력을 비교하였다. 해석 결과 한계압력은 마모 형상이 커질수록 감소하는 경향을 보이며, 임계좌굴압력은 좌굴 형상에 따라 상이한 경향을 보였다. 형상부정계수가 0.1 인 경우 비선형 좌굴 해석으로 얻은 붕괴압력이 작았지만 마모 형상이 커짐에 따라 소성붕괴도 고려되어야 한다. 정확한 임계좌굴압력의 계산을 위해서는 형상부정계수의 정의가 중요하며, 추후 실험을 통하여 형상부정계수를 확보한다면 외압을 받는 마모 실린더의 명확한 구조건전성 평가 가이드라인 제시가 가능할 것으로 판단된다. The cylinder under external pressure, such as steam generator tubes of nuclear power plants, may wear out due to micro-oscillating movements on the contact surface[1]. Since wear defect affects buckling behavior of the cylinder[2], structural integrity assessment of wear cylinder is necessary. In this study, the collapse pressure by linear buckling, non-linear buckling and plastic collapse analyses of a wear cylinder under external pressure are investigated. Various wear shapes with different lengths and depths in the center of the cylinder are considered. It is difficult to obtain accurate collapse pressure based on the linear buckling analysis since the critical pressure decreases due to imperfection of the tube shape[3]. Therefore, we compared linear buckling pressure with both limit pressure and critical buckling pressure obtained by plastic collapse and non-linear buckling analyses. As a result, the limit pressure tends to decrease as the wear size increases as expected, and the critical buckling pressure tends to differ according to the wear shapes and imperfection scale factors. When the imperfection scale factor is 0.1, the main cause of collapse is non-linear buckling, on the other hand, plastic collapse should be considered as the wear size increases. Since the accurate determination of imperfection scale factor is crucial element in the critical buckling pressure assessment, in order to provide the clear guideline of structural integrity assessment for the wear cylinder under external pressure, the experiments on wear cylinder should be conducted.
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체격지수와 성격요인간의 상관관계에 관한 연구 : 대학생을 중심으로 emphasis on college students
노일환,지석태 公州大學校스포츠科學硏究所 2000 스포츠科學硏究所論文集 Vol.- No.14
At first measure the physical characteristics, pelidisis index, ratio of the weight, ratio of the girth of chest and analize the mutual relations of the above mentioned factors and characteristic factors. 1. Indication of the physical characteristics 1) Pelidisis index in group A(fat form) is 9.7% (12 persons) B group B 9the persons) who have well developed(muscles) is 53.6%(66 persons) group D(thin forms) is 7.3%(9 persons) and average persons who have well developed musele indicate about 82.7% (102 persons). 2) As the index number of weight is 37.8, most of the persons have the well developed muscles and the index number of girth of chest is 54.4, therefore all the persons have the normal chest. 2. Pelidisis index and the records of characteristic factors. Observing the pelidisis index by the group, group A(more than 101, 12 persons, fat form) indicate the factors (52.25), the heigher records, in general, group B(100, 96, 36 persons in well developed muscle) and group C(95-91, 66 persons, the average)has the generous and well adapted personalities and social abilities. 3. Mutual relation between the index number of physical characteristics and the factors of characters. 1) Observing the mutual relation of the index number of pelidisis index by the group, group B (100-96) and group C (96-91) has the remarkable mutual relations and since the inspected in group A (more than 101) and group D(under 91) has the lowest or the non-relation, they have another characteristics. 2) As the index number of the surface of the chest and the physical develo pment indicate 37.8, there is no mutual relation in characteristic factors V(.18), A(.22)ad factor F. S. C. M. E. L have the remarkable mutual relation. 3) The index number of the girth of the chest appears normal chest type, and there is almost no mutual relation in factor C(.18) and factor V, F, S, A, M, E, L has thf distinct mutual relation in physical constitution and oharacteristic factors.
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