• Title/Summary/Keyword: Coupled vibration

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Power Flow Analysis of Vibration of Coupled Plates Excited by a Point Force In an Arbitrary Direction (임의의 방향 점가진력에 의한 연성 평판 진동의 파워흐름해석)

  • 최재성;길현권;홍석윤
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.11 no.6
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    • pp.181-192
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    • 2001
  • The power flow analysis (PFA) has been performed to analyze the vibration of coupled plates excited by a point force in an arbitrary direction. The point force generates the out-of-plane vibration associated wish flexural waves and the in-plane vibration associated with longitudinal and shear waves. The energy governing equation for each type of waves was introduced and solved to Predict the vibrational energy density and intensity generated by the out-of-plane and in-plane components of the point force in an arbitrary direction. The wave transmission approach was used to consider the mode conversion at the joint of the coupled plates. Numerical results for vibrational energy density and intensity on the coupled plates were presented. Comparison of the results by PFA with exact results showed that PFA can be an effective tool to predict the spatial variation of the vibrational energy and intensity on the coupled plates at high frequencies.

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Analytical Study on the Free Vibration of Two Rectangular Plates Coupled with Fluid (유체로 연성된 두 직사각 평판의 고유진동에 관한 해석적 연구)

  • 유계형;정경훈;이성철
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.647-651
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    • 2002
  • This study dealt with the free vibration of two identical rectangular plates coupled with fluid. In order to investigate the vibration characteristics of fluid-coupled rectangular plates, an analytical method based on the finite Fourier series expansion and Rayleigh-Ritz method was suggested. A commercial computer code, ANSYS was used to perform finite element analysis and we investigated the vibration characteristics with mode shapes and natural frequencies. As a result, the transverse vibration modes, in-phase and out-of-phase, were observed alternately in the fluid-coupled system. The effect of fluid bounding and plate boundary condition on the fluid-coupled natural frequency were investigated. It was shown that the mode numbers increased, the normalized natural frequencies monotonically increased.

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Vibro-acoustic Analysis of Adjoined Two Rooms Using 3-D Power Flow Finite Element Method (3차원 파워흐름유한요소법을 이용한 인접한 두 실내에서의 진동음향 해석)

  • Kim, Sung-Hee;Hong, Suk-Yoon;Kil, Hyun-Gwon;Song, Jee-Hun
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.20 no.1
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    • pp.74-82
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    • 2010
  • Power flow analysis(PFA) methods have shown many advantages in noise predictions and vibration analysis in medium-to-high frequency ranges. Applying the finite element technique to PFA has produced power flow finite element method(PFFEM) that can be effectively used for analysis of vibration of complicated structures. PFADS(power flow analysis design system) based on PFFEM as the vibration analysis program has been developed for vibration predictions and analysis of coupled structural systems. In this paper, to improve the function of vibro-acoustic coupled analysis in PFADS, the PFFEM has been extended for analysis of the interior noise problems in the vibro-acoustic fully coupled systems. The vibro-acoustic fully coupled PFFEM formulation based on energy coupled relations is extended to structural system model by using appropriate modifications to structural-structural, structural-acoustic and acoustic-acoustic joint matrices. It has been applied to prediction of the interior noise in two room model coupled with panels, and the PFFEM results are compared to those of statistical energy analysis(SEA).

Coupled hydroelastic vibrations of a liquid on flexible space structures under zero-gravity - Part I. Mechanical model

  • Chiba, Masakatsu;Chiba, Shinya;Takemura, Kousuke
    • Coupled systems mechanics
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    • v.2 no.4
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    • pp.303-327
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    • 2013
  • The coupled free vibration of flexible structures and on-board liquid in zero gravity space was analyzed, considering the spacecraft main body as a rigid mass, the flexible appendages as two elastic beams, and the on-board liquid as a "spring-mass" system. Using the Lagrangians of a rigid mass (spacecraft main body), "spring-mass" (liquid), and two beams (flexible appendages), as well as assuming symmetric motion of the system, we obtained the frequency equations of the coupled system by applying Rayleigh-Ritz method. Solving these frequency equations, which are governed by three system parameters, as an eigenvalue problem, we obtained the coupled natural frequencies and vibration modes. We define the parameter for evaluating the magnitudes of coupled motions of the added mass (liquid) and beam (appendages). It was found that when varying one system parameter, the frequency curves veer, vibration modes exchange, and the significant coupling occurs not in the region closest to the two frequency curves but in the two regions separate from that region.

Vibration Analysis for a Coupled MEMS-Gyroscope Design (연성된 MEMS 자이로스코프 모델의 설계를 위한 진동특성 해석)

  • 방선호;신상하;유홍희
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2003.11a
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    • pp.946-969
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    • 2003
  • Vibration analysis for a coupled MEMS gyroscope design is presented in this paper. MEMS gyroscopes have shown that slight mistuning in fabricated process often leads to significant difference of vibration characteristics between expected and real designs. The difference frequently affects the MEMS gyroscope design in a negative way. As long as the coupling between excited and sensed motions exists, such difference occurs inevitably. In this paper, dimensionless parameters that govern the vibration characteristics of coupled MEMS gyroscope are identified and the effects of the parameters on the vibration characteristics are investigated for the design of the MEMS gyroscope.

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Vibration Analysis for a Coupled MEMS-Gyroscope Design (연성된 MEMS 자이로스코프 모델의 설계를 위한 진동 해석)

  • 방선호;신상하;유홍희
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.14 no.8
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    • pp.655-660
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    • 2004
  • Vibration analysis for a coupled MEMS gyroscope design is presented in this paper. Slight mistuning in fabricated MEMS gyroscopes often leads to significant difference of vibration characteristics between expected and real designs. This difference frequently results in a negative effect to the MEMS gyroscope performance. As long as the coupling between excited and sensed motions exists, such difference inevitably occurs. In this paper, dimensionless parameters that govern the vibration characteristics of coupled MEMS gyroscope are identified and the effects of the parameters on the vibration characteristics are investigated.

A Detail Investigation on Coupled Lateral and Torsional Vibration Characteristics in a Speed Increasing Geared Rotor-bearing System (증속 기어전동 로터-베어링 시스템에서 횡-비틀림 연성진동 특성의 상세 고찰)

  • 이안성;하진웅;최동훈
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.2
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    • pp.116-123
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    • 2002
  • Applying a general coupled lateral and torsional vibration finite element model of gear pair element, this paper intends to look into in detail the coupled lateral and torsional vibration characteristics of a turbo-chiller rotor bearing system, having a bull-pinion speed increasing gear. Investigations have been carried out systematically by comparing the uncoupled and coupled natural frequencies and their mode shapes upon varying the gear mesh stiffness with considerations on rotating speeds, and also by comparing the strain energies of lateral and torsional vibration modes. Results hale shown that some modes may hale the coupled lateral and torsional mode characteristics as the gear mesh stiffness Increases over a certain value, and moreover that their associated dominant modes may be different from their initial modes, j.e., a certain dominant mode may change from an initial torsional one to a lateral one or from an initial lateral one to a torsional one.

Dynamic Characteristics of a Turbo-chiller Rotor-Bearing System having a Lateral-Torsional Coupling by Gear Mesh Effect (기어 물림 효과에 의한 횡-비틀림 연성을 갖는 터보-냉동기 로터-베어링 시스템의 동특성)

  • Lee, An-Sung;Ha, Jin-Woong
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.06a
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    • pp.1034-1039
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    • 2000
  • In turbo-machines operated at high speeds through gear speed increasers a precise coupled analysis of lateral and torsional vibrations is required to achieve highly reliable designs with low vibration and low noise levels, where the vibration coupling is due to the gear pair mesh stiffness. In this paper, applying the generalized coupled lateral-torsional finite element model of a gear pair element, has been analyzed a coupled lateral-torsional vibration of the prototype 800 RT turbo-chiller rotor-bearing system with a bull-pinion gear speed increaser. Results have shown that the coupled torsional natural frequencies have decreased due to the coupling effect of lateral vibration and particularly, the 2nd torsional natural frequency and its mode shape have had big changes. However, changes of lateral vibration characteristics have been noticed only at high lateral whirl natural frequencies above 15,000 rpm.

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An Analysis for Coupled Vibration of Vehicle and Bridge Using Fourier Sine Transformation (FOURIER변환을 이용한 차량과 교량의 연성 진동 해석)

  • 류윤선
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1998.04a
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    • pp.45-50
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    • 1998
  • The coupled vibration occurs between traveling vehicle and bridge, when vehicle runs on it. The natural frequency of this coupled system is dependent on the contact position of vehicle and bridge, that is, time-varying system. The calculations of these natural frequencies are very complicated, and often carried out by using Green function theory, series. But, these methods have any limitations, such as, supporting condition, boundary condition. In this paper, on the coupled system constructed by the concentrated mass and elastically supported beam, an analytical method of natural frequency is proposed by using Fourier sine transformation. The results are compared and discussed with numerically calculated ones.

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Response Characteristics of Acoustic Emission Sensor according to Partial Discharge Quantities (부분방전 전하량에 따른 음향방출 센서의 응답특성)

  • Jeong, Yeong-Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.23 no.5
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    • pp.383-387
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    • 2010
  • The response characteristics of AE (acoustic emission) sensors with a coupled vibration mode and a non-coupled vibration mode were investigated according to PD(partial discharge) quantities in XLPE (cross linked polyethylene) sheets and craft papers immersed in insulating oil. The response voltages of a coupled vibration mode AE sensor were linearly proportional to the PD quantities up to 1,000 pC in XLPE sheets, while a non-coupled vibration mode AE sensor did not show the similar linearity. In case of a test of craft papers immersed in insulating oil, a linearity between response voltages and PD quantities was observed up to 550 pC, but after that, similar linearity between response voltage of any types of AE sensor and PD quantities was not shown.