• 제목/요약/키워드: Concentrated Mass

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크랙과 집중질량을 갖는 회전 외팔보의 진동 해석 (Vibration Analysis of a Cracked Beam with a Concentrated Mass Undergoing Rotational Motion)

  • 김민권;유홍희
    • 한국소음진동공학회논문집
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    • 제19권1호
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    • pp.10-16
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    • 2009
  • Modal characteristics of a cracked beam with a concentrated mass undergoing rotational motion are investigated in this paper. Hybrid deformation variables are employed to derive the equations of motion of a rotating cantilever beam. The flexibility due to crack, which is assumed to be open during the vibration, is calculated basing on a fracture mechanics theory. To obtain more general information, the equations of motion are transformed into a dimensionless form in which dimensionless parameters are identified. The effects of the dimensionless parameters related to the angular speed, the depth and location of a crack and the size and location of a concentrated mass on the modal characteristics of the beam are investigated numerically.

Pasternak지반에 지지된 집중질량을 갖는 보강된 변단면 후판의 동적안정해석 (Dynamic Stability Analysis of Stiffened Tapered Thick Plate with Concentrated Mass on Pasternak Foundations)

  • 이용수;김일중
    • 한국소음진동공학회논문집
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    • 제19권12호
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    • pp.1296-1305
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    • 2009
  • This paper has the object of investigating dynamic stability of stiffened tapered thick plate with concentrated mass on Pasternak foundation by means of finite element method and providing kinematic design data for mat of building structures. Finite element analysis of stiffened tapered thick plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is supported on Pasternak foundation, the Winkler foundation parameter is varied with 10, 100, 1000 and the shear foundation parameter is 5, 10, concentrated mass is $0.25m_c$, $1.0m_c$, tapered ratio is 0.25, 0.5. The ratio of In-plane force to critical load is applied as $0.4\sigma_{cr},\;0.6\sigma_{cr},\;0.8\sigma_{cr}$ respectively. This paper analyzed varying tapered ratio.

축방향 왕복운동을 하는 집중질량을 가진 외팔보의 비선형 동적 모델링 및 안정성 해석 (Nonlinear Dynamic Modeling and Stability Analysis of an Axially Oscillating Cantilever Beam With a Concentrated Mass)

  • 홍정환;유홍희
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 춘계학술대회논문집
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    • pp.477-482
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    • 2003
  • A nonlinear modeling method for an axially oscillating cantilever beam with a concentrated mass is presented in this paper. Hybrid deformation variables are employed fur the modeling method with which frequency response characteristics of axially oscillating cantilever beams are investigated. The geometric nonlinear effects of stretching and curvature are considered to accurately predict the frequency response characteristics of the oscillating cantilever beam. The effects of the magnitude and the location on the concentrated mass on the frequency characteristics are investigated. It is found that the dynamic instability is significantly influenced by the two parameters.

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이동 대차 위에 고정되고 집중질량을 갖는 유연보의 운동해석 (Analysis of the Motion of a Flexible Beam Fixed on a Moving Cart and Carrying a Concentrated Mass)

  • 박상덕;정완균;염영일;이재원
    • 대한기계학회논문집A
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    • 제23권11호
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    • pp.1940-1951
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    • 1999
  • In this paper, the equations of motion of a Bernoulli-Euler cantilever beam fixed on a moving cart and carrying a lumped mass concentrated at an arbitrary position along the beam is derived. The motion of the beam-mass-cart system is analyzed through unconstrained modal analysis, and a unified characteristic equation for calculating the natural frequencies of the system is obtained. The changes of natural frequencies and the corresponding mode shapes with respect to the changes in mass ratios of the system and to the concentrated position of the lumped mass are investigated with the frequency equation, which can be generally applied to this kind of systems. The exact and assumed-mode solutions including the dynamics of the base cart are obtained, and the open-loop responses of the system by arbitrarily designed forcing function are given by numerical simulations. The results match well with physical phenomena even at the extreme cases where the concentrated mass is attached to the bottom and to the top of the beam.

회전하는 양단자유보의 동적 안정성에 대한 추력과 집중질량의 영향에 관한 연구 (Effect of a Concentrated Mass on the Dynamic Stability of Spinning Free-Free Beam Subjected to a Thrust)

  • 윤승준;김지환
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 춘계학술대회논문집
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    • pp.695-700
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    • 2000
  • The dynamic stability of spinning beam with free boundary conditions for both edges subjected to a tip follower force $P_0+P_1cos{\Omega}t$ is analyzed. It is studied that the beam has a concentrated mass. and then the effects of the axial locations of the mass are studied. The beam is modelled with the Timoshenko type shear deformations. The Hamilton's principle is used to derive the equations of motion, and the critical spinning speed of a beam subjected to a follower force with various non-dimensional parameters is investigated. The finite elements are used with $C^0$ continuity to analyze the spinning beam model, and the method of multiple scales is tried to investigate the dynamic instability regions. The governing equations of motion involve periodic coefficients, which are not in the form of standard Mathieu-Hill equations. The result shows that the concentrated mass increases the dynamic stability of the spinning free-free beam subjected to a thrust.

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집중질량을 갖는 변단면 보강 후판의 자유진동해석 (Free Vibration Analysis of Stiffened Tapered Thick Plates with Concentrated Masses)

  • 이용수;김일중;오숙경
    • 한국소음진동공학회논문집
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    • 제19권8호
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    • pp.828-837
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    • 2009
  • Recently, as high-rise buildings increase steeply, sub-structures of them are often supported on elastic foundation(in a case of pasternak foundation or winkler foundation). And there are many machines in sub-structures of buildings and slabs of sub-structures are affected by vibration which they make. This paper deals with vibration of plates on elastic foundation. Machines on plates are considered as concentrated mass. This paper has the object of investigating natural frequencies of tapered thick plate on pasternak foundation by means of finite element method and providing kinetic design data for mat of building structures. Free vibration analysis that tapered thick plate with Concentrated Masses in this paper. Finite element analysis of rectangular plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is supported on pasternak foundation. The Winkler parameter is varied with 10, $10^2$, $10^3$ and the shear foundation parameter is 5, 10. This paper is analyzed varying thickness by taper ratio. The taper ratio is applied as 0.0, 0.25, 0.5, 0.75, 1.0. And the Concentrated Mass is applied as P1, Pc, P2 respectively.

탄성지지부가물(彈性支持附加物) 또는 집중질량(集中質量)을 갖는 보강판(補剛板)의 진동해석(振動解析) (Vibration Analysis of Stiffened Plates having a Resiliently Mounted or Concentrated Mass)

  • 한성용;김극천
    • 대한조선학회지
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    • 제23권1호
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    • pp.23-32
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    • 1986
  • By virtue of an application of the receptance method, simplified formulae to calculate natural frequencies of stiffened plates having a resiliently mounted or concentrated mass are obtained. Some numerical results are compared with those based on Lagrange's equation of motion and with experimental results. For the problem formulation the stiffened plate is reduced to an equivalent orthotropic plate, a resiliently mounted mass to a spring-mass system, and mode shapes of the plate are assumed with comparison functions consisting of Euler beam functions. The proposed formulae give results in good conformity to both numerical results based on Lagrange's equation of motion and experimental results for in-phase modes of the coupled system. For out-of-phase modes the conformity is assured only in case that the natural frequency of the attached system is less than a half of that the stiffened plate. It is also found that a resiliently mounted mass having its own natural frequency of about two or more times that of the stiffened plate can be reduced to a concentrated mass with assurance of a few percent error in the frequency.

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질량변화를 갖는 유연한 미사일의 동적 안정성에 관한 연구 (A Study on the Dynamic Stability of a Flexible Missile with Mass Variation)

  • 류봉조
    • 한국정밀공학회지
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    • 제8권4호
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    • pp.107-117
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    • 1991
  • The dynamic stability problem of nonconservative system is one of the important problems. In this study, flexible missile with mass variation is regarded as a free Timoshenko beam subjected to a controlled follower force. The stability was studied numerically through the finite element method. Through the study, the obtained results are as follows: [1] Without force direction control (1) In the case of no mass reduction, the existence of concentrated mass increases critical follower force. (2) Mass reduction rate of the beam slightly effects on the change of critical follower force. [2] With force direction control (1) Shear deformation parameter S contributes insignificantly to the force at instability when $S{\geq}10^4$. (2) With mass variation, increase of concentrated mass increases critical follower force at instbility. (3) The type of promary instability is determined by the sensor location.

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크랙을 가진 밸브 배관계의 강제진동 특성 (Characteristics of Forced Vibration of Valve-pipe Systems with a Crack)

  • 손인수;김창호;조정래
    • 한국소음진동공학회논문집
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    • 제22권11호
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    • pp.1049-1056
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    • 2012
  • The forced vibration response characteristics of a cracked pipe conveying fluid with a concentrated mass are investigated in this paper. Based on the Euler-Bernoulli beam theory, the equation of motion is derived by using Hamilton's principle. The effects of concentrated mass and fluid velocity on the forced vibration characteristics of a cracked pipe conveying fluid are studied. The deflection response is the mid-span deflection of a cracked pipe conveying fluid. As fluid velocity and crack depth are increased, the resonance frequency of the system is decreased. This study will contribute to the decision of optimum fluid velocity and crack detection for the valve-pipe systems.

집중질량 크기 변화해 따른 변단면판의 동적안정해석 (Dynamic Stability Analysis of Tapered Thick Plate on varying Concentrated Mass)

  • 김일중;오숙경
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 2007년도 정기 학술대회 논문집
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    • pp.127-132
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    • 2007
  • This paper has the object of investigating dynamic stability of opening thick plates on Pasternak foundation by means of finite element method and providing Kinematic design data for mat of building structures. Finite element analysis of Tapered Thick plate is done by use of rectangular finite element with 8-nodes. In order to analysis plate which is supported on Pasternak foundation. the Winkler foundation parameter is varied with $10^2$, $10^3$ and the shear foundation parameter is 5, 10. The ratio of force to critical load is applied as 0.4, 0.6, respectively. This paper analyzed varying Tapered Ratio and Concentrated Mass.

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