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유동유체에 의한 불연속 외팔 파이프의 고유치 분기와 플러터 모드
류시웅,임경빈,류봉조 한국소음진동공학회 2004 한국소음진동공학회 논문집 Vol.14 No.10
This paper deals with the dynamic stability and vibration of a discontinuous cantilevered Pipe conveying fluid. The present model consists of two segments with different cross-sections. Governing equations of motion are derived by extended Hamilton's principle, and the numerical scheme using finite element method is applied to obtain the discretized equations. The critical flow velocities and stability maps of the pipe are obtained by changing ratios of second area moment of inertia and mass ratios. Finally, the vibrational modes associated with flutter are shown graphically.
얼음디스펜서와 홈바가 있는 빌트인 양문형 냉장고의 구조해석 및 도어 단차와 개스킷 간극의 평가
류시웅(Si-Ung Ryu),이부윤(Boo-Youn Lee) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.9
냉동실 도어에 얼음디스펜서와 냉장실 도어에 홈바가 장착된 빌트인 양문형 냉장고 모델에 대하여 유한요소해석 프로그램인 ANSYS를 사용하여 캐비닛과 도어를 통합한 유한요소모델을 구성하고 변형해석을 수행하였다. 하중으로는 냉장고가 조립된 조건, 그리고 캐비닛 선반과 도어 배스킷에 적재되는 식품 부하물 하중과 냉장고 정상 작동 시의 온도분포에 의한 열하중조건을 고려하였다. 캐비닛과 도어의 변형량 해석결과에 기반하여 냉동실 도어와 냉장실 도어 사이의 상하단차와 앞뒤단차를 평가하고, 냉기 밀봉에 영향을 미치는 캐비닛 전면과 도어 내면 사이에 위치한 도어 개스킷의 간극의 증가량을 평가하였다. 부하물이 없고 냉장고가 작동하지 않는 조건의 해석결과 계산된 상하단차와 앞뒤단차는 제품 출하 시의 허용기준을 만족하는 것으로 나타났다. 부하물이 투입되고 냉장고가 정상 작동하는 열하중조건의 해석결과 계산된 상하단차와 앞뒤단차는 조립조건에 비해 증가하며 특히 앞뒤단차가 크게 증가시키는 것으로 나타났다. 열하중조건의 해석결과 계산된 캐비닛 전면과 도어 내면의 변위로부터 도어의 사각 테두리에 부착되는 개스킷 간극의 증가량을 평가하였다. 최대 간극 증가량은 냉동실 도어의 좌측 테두리에서 발생하며 제조업체에서 정한 허용기준을 만족하는 것으로 나타났다. A cabinet-door integrated finite element model for a built-in side-by-side refrigerator with an ice dispenser and home bar was constructed, and its deformation was analyzed by ANSYS. As loads, the food load in the shelf and baskets, and thermal load occurring during the normal operation condition were considered. From results of the analyses, the door height difference (DHD) and door flatness difference (DFD) between the two doors, and the increase in the gap of the door gasket, which affects the sealing of cool air in the cabinet, were derived. As results of an evaluation of the differences, the DHD and DFD under the assembled condition satisfied the acceptance criteria of the manufacturer. The food and thermal loads increased the DHD and DFD due to thermal deformation, and the DFD increased significantly. In addition, the increase in the gap of door gasket located between the cabinet and doors was derived from the results of displacements under the food and thermal loads. The evaluation showed that the maximum increase in gap appeared at the left edge of the freezing compartment gasket, which satisfied the acceptance criteria of the manufacturer.
류봉조,류시웅,오부진,김효준 한국소음진동공학회 2001 한국소음진동공학회 논문집 Vol.11 No.6
The paper presents the dynamic stability of a flexible shoe in drum brake systems subjected to a frictional force. The frictional force between the drum and the shoe is assumed as a distributed frictional force, while the shute is modeled as an elastic beam supported by two translational springs at both ends and elastic foundations. Governing equations of motion are derived by energy expressions, and their numerical results are obtained by employing the finite element method. The critical distributed frictional force and the instability regions are demonstrated by changing the stiffness of two translational springs and elastic foundation parameters. It is also shown that the beam loses its stability by flutter and divergence depending on the stiffness of elastic supports and elastic foundation parameters. Time responses of beams corresponding to their instability types are also demonstrated.
부분 탄성기초를 갖고 종동력을 받는 보의 플러터 불안정
류봉조,류시웅,조창기,이종원 한밭대학교 생산융합기술연구소 2004 생산기반기술연구소 논문집 Vol.4 No.1
In this paper, the dynamic stability of a cantilevered beam partially attached to elastic foundations and subjected to a follower force is studied. The beam has a concentrated mass at an arbitrary position on it. Governing equations are derived by extended Hamilton's principle and the finite element formulations are applied to obtain discretized equations. The influence of some parameters, such as the elastic foundation parameter, the position of partial elastic foundations, mass ratios and rotary inertia of the concentrated mass on the critical flutter load is investigated. Finally, the optimal attachment ratio of partial elastic foundation which maximizes the critical flutter load is found.