• 제목/요약/키워드: Natural Vibration Characteristics

검색결과 1,093건 처리시간 0.027초

비접촉 원자간력 현미경의 탐침 외팔보 진동특성에 따른 성능 평가 (Performance Evaluation of Non-contact Atomic Force Microscopy Due to Vibration Characteristics of Cantilever)

  • 박준기;권현규;홍성욱
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 춘계학술대회논문집
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    • pp.263-268
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    • 2003
  • This paper presents a result of performance evaluation fur non-contact scanning probe microscopy with respect to the vibration characteristics of cantilevers with tips. One of the current issues of the scanning probe microscopy technology is to increase the measurement speed, which is closely tied with the dynamic characteristics of cantilevers. The primary concern in this research is to investigate the relation between the maximum possible speed of non-contact scanning probe microscopy and the dynamic characteristics of cantilevers. First, the finite element analysis is made fur the vibration characteristics of various cantilevers in use. The computed natural frequencies of the cantilevers are in good agreement with measured ones. Then, each cantilever is tested with topographic measurement for a standard sample with the scanning speed changed. The performances of cantilevers are analyzed along with the natural frequencies of cantilevers. Experiments are also performed to test the effects of how to attach cantilevers in the piezo-electric actuator. Finally, measurement sensitivity has been analyzed to enhance the performance of scanning probe microscopy.

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스퍼기어와 헬리컬기어의 동적 특성 비교 (Comparison of Dynamic Characteristics of Spur Gears and Helical Gears)

  • 박찬일;조도현
    • 한국소음진동공학회논문집
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    • 제22권4호
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    • pp.358-364
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    • 2012
  • This work dealt with dynamic characteristics of spur gear and helical gear system to understand the gear vibration and noise. To find out dynamic characteristics in the gear system, a finite element model and an analytic model for the gear system were used. Using the models, the natural frequency and mode-shape characteristics of spur gears and helical gears were calculated. Two models show that natural frequencies of helical gears were lower than those of spur gears. Mode-shape characteristics of gear pairs by analytical model and some issues of finite element modeling were also discussed. Impact test was used to validate the finite element model.

결함을 가진 증기발생기 U-튜브의 진동특성 (Vibration Characteristics of Steam Generator U-tubes with Defect)

  • 조종철;정명조;김웅식;김효정;김태형
    • 한국소음진동공학회논문집
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    • 제13권5호
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    • pp.400-408
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    • 2003
  • This paper investigates the vibration characteristics of steam generator (SG) U-tubes with defect. The operating SG shell-side flow field conditions for determining the fluidelastic instability parameters such as added mass are obtained from three-dimensional SG flow calculation. Modal analyses are performed for the U-tubes either with axial or circumferential flaw with different sizes. Special emphases are on the effects of flaw orientation and size on the modal and instability characteristics of tubes, which are expressed in terms of the natural frequency, corresponding mode shape and stability ratio. Also, addressed is the effect of the internal pressure on the vibration characteristics of the tube.

대형선박의 추진기 진동 모드 특성 (Vibration mode characteristics on a propeller in very large vessel)

  • 김재홍;조대승;한성용
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 춘계학술대회논문집
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    • pp.955-962
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    • 2002
  • According to the trends of construction of large size vessel with high power, the natural frequencies of the bending modes of propeller blades have been lower than the past. Therefore, it is expected that the noise and vibration problems of the marine propeller are frequently occurred. As main issue of the propeller noise and vibration problem, the cavitation noise and singing noise due to the flow induced excitation of the bending modes of propeller blade in the high frequency range has been studied by the hydrodynamic researchers in the view point of the excitation force reduction. In this paper, the vibration mode characteristics of propeller with a large diameter in very large vessel are investigated by the vibration analysis of the finite element method using MSC/Nastran and the vibration measurement by the impact test on the propeller blade. According to the results, the natural frequencies of various blade bending modes in water entrained condition could be estimated from the natural frequencies taken by the measurement and free vibration analysis in the dry condition, and it could be estimated how the high frequency noise such as singing is generated from the blade bending modes.

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단순 지지 경계 조건을 가진 임의 형상 평판의 고정밀도 자유 진동 해석을 위한 NDIF법 개발 (Development of NDIF Method for Highly Accurate Free Vibration Analysis of Arbitrarily Shaped Plates with Simply Supported Boundary Condition)

  • 강상욱;우윤환
    • 한국소음진동공학회논문집
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    • 제21권2호
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    • pp.186-193
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    • 2011
  • The NDIF method(non-dimensional dynamic influence function method) for free vibration analysis of arbitrarily shaped plates with the simply supported edge is newly developed in the paper. In order to extract the system matrix that gives the natural frequencies and natural modes of the plate of interest, the difficulty of measuring higher differential terms involved in the simply supported boundary condition is successfully overcome. Finally, the excellence of the characteristics of convergence and accuracy of the proposed method is shown through two verification examples, which indicate that natural frequencies and natural modes obtained by the proposed method are very accurate and swiftly converged even though a small number of nodes are used compared with FEM.

수치해석에 의한 심수 탱크구조물의 진동에 관한 연구 (Numerical Analysis of Vibration Characteristics in Deep Water Tank)

  • 배성용
    • 한국소음진동공학회논문집
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    • 제13권10호
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    • pp.791-797
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    • 2003
  • A liquid storage rectangular tank structures are used In many fields of civil, mechanical and marine engineering. Especially, Ship structures have many tanks In contact with Inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks in contact with fluid near engine or propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tank structures. In the previous report, we have developed numerical tool of vibration analysis of 3-dimensional tank structure using finite elements for plates and boundary elements for fluid region. In the present report, using the numerical analysis, vibrations characteristics In deep water tank are investigated and discussed.

유체를 이송하는 양단 고정된 반원관의 면내/면외 진동 특성 (Vibration Characteristics of a Semi-circular Pipe Conveying Fluid with Both Ends Clamped)

  • 정두한;정진태
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 춘계학술대회논문집
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    • pp.252-257
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    • 2004
  • Free vibration of a semi-circular pipe conveying fluid is analyzed when the pipe is clamped at both ends. To consider the geometric non-linearity, this study adopts the Lagrange strain theory and the extensibility of the pipe. By using the extended Hamilton principle, the non-linear partial differential equations are derived, which are coupled to the in-plane and out-of\ulcornerplant: motions. To investigate the vibration characteristics of the system, the discretized equations of motion are derived from the Galerkin method. The natural frequencies are computed from the linearized equations of motion in the neighborhood of the equilibrium position. From the results. the natural frequencies for the in-plane and out-of-plane motions are vary with the flow velocity. However, no instability occurs the semi-circular pipe with both ends clamped, when taking into account the geometric non-linearity explained by the Lagrange strain theory.

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시운전 시험을 통한 한국형 고속전철 차체진동 특성의 분석 및 평가 (Analysis and Evaluation of Body Vibration Characteristics for Korean High Speed Train through On-line Test)

  • 김영국;김석원;박찬경;김기환;목진용
    • 한국철도학회논문집
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    • 제6권4호
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    • pp.286-293
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    • 2003
  • The prototype of Korean high speed train (HSR350), composed of two power cars, two motorized cars and three trailer cars, has been designed, fabricated and tested. In this paper, the body vibration has been reviewed from the viewpoint of the vehicle's safety and the vibration limits for components and sub-assemblies mounted on the car-body using by the experimental method. And, the dynamic characteristics, such as jerk, natural mode and kinematic mode, have been reviewed. The KHST has been run to 300 km/h in the KTX line and the results of on-line test show that it has no problems in the vehicle's safety and the vibration limits. And the characteristics of body vibrations has been predicted at 350 km/h by fitting curve about the measured acceleration signals.

수치해석에 의한 심수 탱크구조물의 진동에 관한 연구 (Numerical Analysis of Vibration Characteristics in Deep Water Tank)

  • 배성용;홍봉기;배동명
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 춘계학술대회논문집
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    • pp.1079-1084
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    • 2003
  • A liquid storage rectangular tank structures are used in many fields of civil, mechanical and marine engineering. Especially, Ship structures have many tanks in contact with inner or outer fluid, like ballast, fuel and cargo tanks. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance with exciting force of engine and propeller. Vibration characteristics of these thin walled tanks ill contact with fluid near engine or propeller are strongly affected by added mass of containing fluid. Therefore it is essentially important to estimate the added mass effect to predict vibration of the tank structures. In the previous report, we have developed numerical tool of vibration analysis of 3-dimensional tank structure using finite elements for plates and boundary elements for fluid region. In the present report, using the numerical analysis, vibrations characteristics in deep water tank are investigated and discussed.

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철도차량에서 사용하는 부유상구조의 진동절연특성에 관한 연구 (Study on the Vibration Reduction Characteristics of Floating Floors Used in Railway Vehicles)

  • 우관제;박희준
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2006년도 추계학술대회 논문집
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    • pp.305-309
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    • 2006
  • In this paper vibration reduction characteristics of floating floors used in railway vehicles are studied. Vibration reduction characteristics are compared through a series of tests for elastically-coupled floor and rigidly-coupled floor. It was found that elastically-coupled floor has larger vibration reduction amount than rigidly-coupled floor. Around the fundamental natural frequency, however, elastic floor has poor vibration reduction effect than rigid floor. Measures to reduce structure-borne noise are also discussed based on the test results. Structure-borne noise for running railway vehicles cannot be reduced by an effort to deviate resonance between natural frequency of floors and major exciting forces. Instead, reducing vibration level of top floor and using covers which have low sound radiation coefficient will be effective for reducing structure-borne noise.

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