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종동력을 받는 탄성지지된 외팔보의 동적 안정성에 미치는 스프링위치와 상수의 영향
류봉조,권경우,명태식 대한기계학회 1994 대한기계학회논문집 Vol.18 No.6
The influences of spring position and spring stiffness on the critical force of a cantilevered beam subjected to a follower force are investigated. The spring attatched to the beam is assumed to be a translational one and can be located at arbitrary positions of the beam as it has not been assumed so far. The effects of transeverse shear deformation and rotary intertia of the beam are also included in this analysis. The charateristic equation for the system is derived and a finite element model of the beam using local coordinates is formulated through extended Hamilton's principle. It is found that when the spring is located at position less than that of 0.5L, the flutter type instability only exists. It is shown that the spring position approaches to the free end of the beam from its midpoint, instability type is changed from flutter to divergence through the jump phenomina according to the increase of spring stiffness.
두 파라미터 탄성기초를 갖는 테이퍼진 티모센코 보의 진동 및 안정성
류봉조,임경빈,윤충섭,류두현 한국소음진동공학회 2000 소음 진동 Vol.10 No.6
본 논문은 이중 탄성기초 위에 놓인 테이퍼진 티모센코 보의 진동과 동적 안정성에 대한 연구로써, 이중 탄성기초는 지반모델에서 흔히 이용되는 분포 Winkler 스프링들과 전단기초층으로 구성된다. 보의 전단변형과 회전관성이 고려되고, 지배방정식은 Halmilton원리를 이용한 에너지 표현식에 의해 유도된다. 고유진동수와 좌굴하중을 구하기 위해 관계되는 고유치 문제를 풀며, 출력을 받는 보의 진동에 대한 수치해석결과들이 제시되는 다른 방법을 사용한 유용한 해의 결과들과 비교된다. 출력을 받고 탄성기초 위에 놓인 테이퍼진 티모센코 보의 고유진동수, 모드 형상, 그리고 임계하중 값들이 다양한 테이퍼 두께의 비, 전단기초 파라미터, Winkler 기초파라미터, 경계조건의 변화에 대해 조사된다. The paper describes the vibration and stability of tapered beams on two-parameter elastic foundations. The two-parameter elastic foundations are constructed by distributed Winkler springs and a shearing layer as of ten used in soil models. The shear deformation and the rotatory inertia of a beam are taken into account. Governing equations are derived from energy expressions using Hamilton\`s principle. The associated eigenvalue problems are solved to obtain the free vibration frequencies or the buckling loads. Numerical results for the vibration of a beam with an axial force are presented and compared when other solutions are available. Vibration frequencies, mode shapes, and critical forces of a tapered Timoshenko beam on elastic foundations under an axial force are investigated for various thickness ratios, shear foundation parameters, Winkler foundation parameters and boundary conditions.
종동력을 받는 불균일 자유보의 동적 안정성에 관한 연구
류봉조 大田工業大學 1989 한밭대학교 논문집 Vol.6 No.2
ABSTRACT In this paper, dynamic stability analysis is carded out for discontinuous, free Timoshenko beam, moving in a plane under the action of constant follower force. Finite element method by using extended Hamilton's principle, is applied to the study. The results of analysis show that 1) The existence of concentrated mass in- creases critical follower force. 2) Without direction control, the rotary inertia of concentrated mass is negligible for the critical follower force in the region of (β≤s 10-3. 3) With direction control, shear deformation of the beam does not effect on the critical follower force at S≥IO3. 4) With direction control, at the location of concentrated mass μ = 1.0, the maximum critical follower force is appeared. In this paper, dynamic stability analysis is carried out for discontinuous, free Timoshenko beam, moving in a plane under the action of constant follower force. Finite element method by using extended Hamilton's principle, is applied to the study. The results of analysis show that 1) The existence of concentrated mass increases critical follower force. 2) Without direction control, the rotary inertia of concentrated mass is negligible for the critical follower force in the region of β≤10^(-3). 3) With direction control, shear deformation of the beam does not effect on the critical follower force at S≥10^3. 4) With direction control, at the location of concentrated mass μ = 1.0, the maximum critical follower force is appeared.
류봉조 大田産業大學校 1995 한밭대학교 논문집 Vol.12 No.0201
The present paper describes the study trends on vibaration charateristics and dynamic stability of beams subjected to a nonconservative force. One specific objective of the study is to introduce the three groups of non-conservative problems and their characteristics proposed so far. A second objective is to introduce the techinque solving the governing differential equations of nonconservative stability problems approximately. Comparison of the critical force of the experiment and finite element formulation of cantilevers is shown, and the existence of a good correlation between two solutions is highlighted.
아접선력을 받는 보의 동적안정성에 미치는 고유치 감도해석
류봉조,최상경 한밭대학교 산업과학기술연구소 2001 논문집 Vol.5 No.-
This paper deals with the eigenvalue sensitivity of a finite element formulation on vibration and dynamic stability of an elastically restrained cantilevered beam under subtangential forces. Governing equations are derived by energy expressions using extended Hamilton's principle. In order to more quickly and efficiently obtain the critical subtangential force for a given system, a technique which utilizes the eigenvalue sensitivity with respect to the system parameter is introduced. More accurate results are obtained for both variations in the spring position, spring stiffness, as well as the subtangential parameter.