• Title/Summary/Keyword: 집중 질량

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Lumped Parameter Model of Transmitting Boundary for the Time Domain Analysis of Dam-Reservoir System (댐의 시간영역 지진응답 해석을 위한 호소의 집중변수모델)

  • 김재관;이진호;조정래
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.4
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    • pp.27-38
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    • 2001
  • A mechanical lumped parameter model is proposed for the dynamic modeling of a semi-infinite reservoir. A semi-analytic transmitting boundary is derived for a semi-infinite 2-D reservoir of constant depth. The characteristics of the solution are examined in both frequency and time domains. Mass, damping and spring coefficients of the mechanical model are obtained to preserve the major features of the solution such as eigenfrequencies and the shapes of Bessel functions that appear as kernels in the convolution integrals. The lumped parameter model in its final form consists of two masses, a spring and two dampers for each eigenfrequency. Application examples demonstrated that the new lumped parameter model could be used for the time domain analysis of dam-reservoir systems.

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Prediction of Dynamic Characteristics of Continuous Systems Due to the Mass Modification (질량변경에 따른 연속계의 동특성변화 예측)

  • 이정윤;최상렬;박천권;오재응;정석주
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.2
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    • pp.248-256
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    • 1993
  • This paper deriver the generalized mass to find dynamic characteristics and its derivatives of a continous system. And a new sensitivity analysis method is presented by using the amount of change of generalized mass and vibrational mode caused by the variation of lumped and distributed mass. In this paper, to get or detect appropriate results, cantilever beam and stepped beam are used. Deviations of sensitivity coefficient, natual frequency, vibrational mode and transfer function are calculated as result, and compared with the theoretical exact values.

A Study on the Interaction Effect Between Spray Fan Formed by Gas/Liquid Swirl Injector (기체/액체를 사용하는 Swirl 인젝터의 간섭효과에 관한 연구)

  • Joung, Rae-Hyuck;Kim, Yoo;Cha, Young-Ran;Park, Joung-Bae;Park, Uoo-Dong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.1 no.1
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    • pp.1-7
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    • 1997
  • Experimental study was carried out to investigate the interaction effect between spray fan formed by gas/liquid swirl injector. Test variables were supply pressure and injector distance. Water and air were the simulant for the experiment. For water supply only; Collected water mass was concentrated at the lower part of the two spray fan, but this effect was reduced with increasing supply pressure. Both air and water supply1; Collected water mass was again concentrated at the lower part of the impingement point, but this effect was reduced when air/water supply pressure ratio was increased.

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Free vibrational analysis of a circular ring with a concentrated mass (집중질량을 가지는 원환의 자유진동 해석)

  • 홍진선;김석현;이장무
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.1
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    • pp.170-176
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    • 1987
  • This study is concerned with dynamic characteristics of a circular ring with a concentrated mass attached. The equations of motion are set up and are solved by using Laplace transformation. The ratio of a concentrated mass to the mass of circular ring is used as a parameter. Experiment was performed by employing impulse test and the results show good agreement with those of analysis. The results of this study can be utilized in vibrational analysis of axisymmetric shells with slight asymmetries.

Vibration analysis of a pretwisted rotating blade with a concentrated mass (집중질량과 초기 비틀림각을 갖는 회전블레이드의 진동해석)

  • Kwak, Joo-Young;Yoo, Hong-Hee
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.1
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    • pp.190-197
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    • 1998
  • Equations of motions of a pretwisted rotating blade with a concentrated mass in an arbitrary position are derived. The flapwise and chordwise equations are coupled to each other due to the pretwist angle of the blade. As the angular speed, hub radius ratio, pretwist angle and concentrated mass vary, the vibration characteristics of the blade change. It is found that eigenvalue lociveering phenomena occur between two closing loci due to the pretwist angle. The effect of the pretwist angle on the critical angular speed and location of the concentrated mass on the natural frequencies are also investigated.

Parametric instability of the nonconservative elastic system (비보존 탄성계의 파라미터 불안정)

  • 박영필;노광춘
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.11 no.1
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    • pp.124-131
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    • 1987
  • The parameteric instability of the cantilever beam carrying two concentrated masses subjected to a periodic follower force is investigated theoretically and experimentally. The effects of the constant follower force and the periodic follower force the mass ratio and the location of the concentrated mass on the parametric instability of the system are discussed. In experiment, the nonconservative follower force is produced by the magnetic force of the electromagnet. The theoretical and the experimental results on the parameteric instability are in good agreement each other.

Nonlinear Dynamic Modeling and Stability Analysis of an Axially Oscillating Cantilever Beam with a Concentrated Mass (축방향 왕복 운동을 하는 집중 질량을 가진 외팔보의 비선형 동적 모델링 및 안정성 해석)

  • 홍정환;유홍희
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.13 no.11
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    • pp.868-874
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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 for 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 size and the location of the concentrated mass on the frequency characteristics are investigated. It is found that the dynamic instability is significantly influenced by the two parameters.

Vibration Analysis of a Rotating Blade Considering Pre-twist Angle, Cross Section Taper and a Concentrated Mass (초기 비틀림 각과 단면 테이퍼 그리고 집중질량을 갖는 회전하는 블레이드의 진동해석)

  • Kim, Hyung Yung;Yoo, Hong Hee
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.23 no.4
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    • pp.338-346
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    • 2013
  • Equations of motion of a rotating blade considering pre-twist angle, cross section taper and a concentrated mass are derived using the hybrid deformation variable modeling method. For the modeling of a concentrated mass which is located at an arbitrary position of the blade, a Dirac delta function is employed for the mass density function. The final equations for the vibration analysis are transformed into a dimensionless form using several dimensionless parameters. The effects of the dimensionless parameters on the vibration characteristics of the rotating blade are investigated through numerical analysis.

Vibration Analysis of Rotating Cantilever Plates with a Concentrated Mass (집중 질량을 가진 회전하는 외팔 평판의 진동 해석)

  • 양정식;유홍희
    • Journal of KSNVE
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    • v.8 no.6
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    • pp.1130-1136
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    • 1998
  • A modelling method for the vibration analysis of rotating cantilever plates with a concentrated mass is presented. The equations of motion for the rotating plates with a concentrated mass located in an arbitrary position are derived and transformed into a dimensionless form. For the mathematical modelling of the concentrated mass. a mass density Dirac delta function is used. The effects of concentrated mass and its location. angular speed. plate aspect ratio. and hub radius of the rotating plate on the natural frequencies are studied. Particularly. mode shape variations due to some parameter variations are investigated.

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Dynamic Stability Analysis of an Axially Oscillating Cantilever Beam with a Concentrated Mass (축방향 왕복운동을 하는 집중질량을 가진 외팔보의 동적 안정성 해석)

  • 현상학;유홍희
    • Journal of KSNVE
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    • v.11 no.1
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    • pp.118-124
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    • 2001
  • The effect of a concentrated mass on the regions of dynamic instability of an axially oscillating cantilever beam is investigated in this paper. The equations of motion are derived using Kane's method and the assumed mode method. It is found that the bending stiffness is harmonically varied by axial inertia forces due to oscillating motion. Under the certain conditions between oscillating frequency and the natural frequencies, dynamic instability may occur and the magnitude of the bending vibration increase without bound. By using the multiple time scales method, the regions of dynamic instability are obtained. The regions of dynamic instability are found to be depend on the magnitude of a concentrated mass or its location.

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