• 제목/요약/키워드: Modal dynamic analysis

검색결과 926건 처리시간 0.036초

연료전지용 터보압축기 회전축의 동특성 해석에 관한 연구 (A Study on the Dynamic Analysis in the Shaft of Turbo-Blower for Fuel Cell)

  • 김홍건;나석찬;김성철;강영우;양균의;이희관;최문창
    • 한국공작기계학회논문집
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    • 제13권1호
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    • pp.81-87
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    • 2004
  • A 3-D FEM (Finite Element Method) analysis of the turbo-blower shaft attached to a fuel cell was performed using Lanczos algorithm. The modal analysis was analyzed in order to investigate natural frequency and maximum displacement for 10 times. It was found that the first mode of natural frequency is 109.1Hz with the maximum displacement of 0.16mm while the tenth mode of natural frequency is 2464Hz with the maximum displacement of 0.25mm. Consequently, the results of modal analysis of the turbo-blower for a fuel cell system show good dynamic responses.

에어베어링으로 지지된 캐리지 구조물의 동특성 해석 (Dynamic Characteristics Analysis of the Carriage Structure Supported by Air Bearing)

  • 정순철;김덕수;유충준;장승환;이재응
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2003년도 춘계학술대회논문집
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    • pp.1107-1114
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    • 2003
  • In this thesis, the dynamic characteristic analysis of carriage structure supported by air bearings were peformed. Toward this end, the characteristics of air bearing were numerically analyzed to estimate the stiffness of the air bearing and the clearance between air bearing and guide surface. The modal analysis of the carriage structure was peformed by using finite element method, and the experimental modal analysis was also performed to validate the finite element model, where rigid body modes were compared to validate the stiffness of the air bearings. From the results, the air spring stiffness can be estimated within the range of acceptable accuracy under any pressure and clearance condition.

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Dynamic characteristics of CFRP-Strengthened wooden beams: Experimental and numerical study

  • Nur Sunar;Habib Uysal
    • Structural Engineering and Mechanics
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    • 제89권3호
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    • pp.323-334
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    • 2024
  • Physical and chemical factors can cause traditional timber constructions to lose structural integrity. Knowing the dynamic properties of the building components is vital to avoid damage to the buildings from dynamic effects, a subset of physical effects. In this work, spruce and scotch pine wooden beams that had been strengthened in three distinct ways with carbon fiber strengthened polymer (CFRP) were investigated for changes in their dynamic properties. For this, CFRP was used to strengthening unstrengthened wooden beams in the form of bottom confinement, U-shaped confinement, and full confinement after the dynamic parameters of the beams were determined. By using experimental modal analysis with both free-free and fixed-fixed boundary conditions, the beams'initial natural frequencies were identified.

Modal testing and finite element model calibration of an arch type steel footbridge

  • Bayraktar, Alemdar;Altunisk, Ahmet Can;Sevim, Baris;Turker, Temel
    • Steel and Composite Structures
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    • 제7권6호
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    • pp.487-502
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    • 2007
  • In recent decades there has been a trend towards improved mechanical characteristics of materials used in footbridge construction. It has enabled engineers to design lighter, slender and more aesthetic structures. As a result of these construction trends, many footbridges have become more susceptible to vibrations when subjected to dynamic loads. In addition to this, some inherit modelling uncertainties related to a lack of information on the as-built structure, such as boundary conditions, material properties, and the effects of non-structural elements make difficult to evaluate modal properties of footbridges, analytically. For these purposes, modal testing of footbridges is used to rectify these problems after construction. This paper describes an arch type steel footbridge, its analytical modelling, modal testing and finite element model calibration. A modern steel footbridge which has arch type structural system and located on the Karadeniz coast road in Trabzon, Turkey is selected as an application. An analytical modal analysis is performed on the developed 3D finite element model of footbridge to provide the analytical frequencies and mode shapes. The field ambient vibration tests on the footbridge deck under natural excitation such as human walking and traffic loads are conducted. The output-only modal parameter identification is carried out by using the peak picking of the average normalized power spectral densities in the frequency domain and stochastic subspace identification in the time domain, and dynamic characteristics such as natural frequencies mode shapes and damping ratios are determined. The finite element model of footbridge is calibrated to minimize the differences between analytically and experimentally estimated modal properties by changing some uncertain modelling parameters such as material properties. At the end of the study, maximum differences in the natural frequencies are reduced from 22% to only %5 and good agreement is found between analytical and experimental dynamic characteristics such as natural frequencies, mode shapes by model calibration.

다단계 긴장 PSC 거더 철도교량의 동특성 실험 및 주행열차하중 해석에 의한 동적성능 평가 (Dynamic Performance Estimation of the Incrementally PSC Girder Railway Bridge by Modal Tests and Moving Load Analysis)

  • 김성일;김남식;이희업
    • 대한토목학회논문집
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    • 제26권4A호
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    • pp.707-717
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    • 2006
  • 근래에 들어 기존의 PSC 거더 교량 외에 다양한 형태의 교량이 개발되고 있으며, 다단계 긴장에 의한 PSC 거더교는 대표적인 예이다. 다단계 긴장 PSC 거더교는 구조적 개념에 따라 자중을 줄이고 경간을 장대화할 수 있는 장점을 갖고 있다. 그러나, 이와 같은 장대화된 보다 유연한 교량은 구조적 안전성 및 사용성을 고려한 주행열차하중에 대한 동적거동 검토가 필수적이며, 철도교량의 주행열차하중에 대한 동적성능평가를 위한 정확한 동특성 입력은 매우 중요하다. 본 연구에서는 정확한 고유진동수 및 감쇠비 추출을 위하여 25m 실물 다단계 긴장 PSC 거더를 제작하여 시공단계별 모달테스트를 수행하였다. 모달테스트를 위한 가진방법으로 기존의 충격햄머에 의한 방법 외에 디지털 콘트롤에 의한 가진기를 사용하여 보다 정확한 주파수응답 함수를 얻고자 하였다. 또한, 시공단계별 구조계 변화 및 긴장에 의한 동특성 변화를 고찰하기 위하여 시공단계별 실험을 수행하였다. 모달테스트 결과에 의한 동특성 값을 주행열차하중 해석에 적용하여 다양한 매개변수연구를 통한 철도교량 동적성능평가를 수행하였다. 동적처짐, 충격계수, 바닥판의 연직가속도, 단부꺾임각 등에 대하여 열차별, 속도별 동적해석을 수행하여 국내외 철도교량 동적성능 평가기준과 비교하였다.

Timoshenko 이론과 유한요소법을 이용한 모터내장형 고속주축계의 정특성/동특성 해석시스템 개발 (Development of a Static and Dynamic Analysis System for Motor-Integrated High-Speed Spindle Systems Using Timoshenko Theory and Finite Element Method)

  • 이용희;김석일;김태형;이재윤
    • 한국정밀공학회지
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    • 제15권8호
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    • pp.11-16
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    • 1998
  • Recently, the motor-integrated spindle systems have been used to simplify the machine tool structure, to improve the motion flexibility of machine tool, and to perform the high-speed machining. In this study, a static and dynamic analysis system for motor-integrated high-speed spindle systems is developed based on Timoshenko theory, finite element method and windows programming techniques. Since the system has various analysis modules related to static deformation analysis, modal analysis, frequency response analysis, unbalance response analysis and so on, it is useful in performing systematically the design and evaluation processes of motor-integrated high-speed spindle systems under windows GUI environment.

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고세장비 항공기의 모드 시험 및 동특성 유한요소모델 개선 (Modal Test and Finite Element Model Update of Aircraft with High Aspect Ratio Wings)

  • 김상용
    • 한국소음진동공학회논문집
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    • 제22권5호
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    • pp.480-488
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    • 2012
  • The aircrafts with high aspect ratio wings made by a composite material have been developed, which enable high energy efficiency and long-term flight by reducing air resistance and structural weight. However, they have difficulties in securing the aeroelastic stability such as the flutter because of their long and flexible wings. The flutter is unstable self-excited-vibration caused by interaction between the structural dynamics and the aerodynamics. It should be verified analytically prior to first flight test that the flutter does not happen in the range of flight mission. Normally, the finite element model is used for the flutter analysis. So it is important to construct the finite element model representing dynamic characteristics similar to those of a real aircraft. Accordingly, in this research, to acquire dynamic characteristics experimentally the modal test of the aircraft with high aspect ratio composite wings was conducted. And then the modal parameters from the finite element analysis(FEA) were compared with those from the modal test. To make analysis results closer to test results, the finite element model was updated by means of the sensitivity analysis on variables and the optimization. Finally, it was proved that the updated finite element model is reliable as compared with the results of the modal test.

동적 평형위치에 있는 다물체계의 모드특성에 미치는 공차의 영향 분석을 위한 해석적 방법 (Analytical Method to Analyze the Effect of Tolerance on the Modal Characteristic of Multi-body Systems in Dynamic Equilibrium)

  • 김범석;유홍희
    • 한국소음진동공학회논문집
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    • 제17권7호
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    • pp.579-586
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    • 2007
  • Analytical method to analyze the effect of tolerance on the modal characteristic of multi-body systems in dynamic equilibrium position is suggested in this paper. Monte-Carlo method is conventionally employed to perform the tolerance analysis. However, Monte-Carlo method spends too much time for analysis and has a greater or less accuracy depending on sample condition. To resolve these problems, an analytical method is suggested in this paper. Sensitivity equations for damped natural frequencies and the transfer function are derived at the dynamic equilibrium position. By employing the sensitivity information of mass, damping and stiffness matrices, the sensitivities of damped natural frequencies and the transfer function can be calculated.

경사기능재료 사각판의 열탄성 및 동적해석 (Thermoelastic and Dynamic Analysis of Functionally Graded Rectangular Plates)

  • 김영완
    • 한국소음진동공학회논문집
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    • 제15권4호
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    • pp.474-482
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    • 2005
  • A theoretical method is presented to investigate the thermoelastic and dynamic response of functionally graded material (FGM) rectangular plates made up of metal and ceramic. The temperature is assumed to be constant in the plane of the plate and to vary in the thickness direction only. Material properties are assumed to be temperature-dependant, and vary continuously through the thickness according to a power law distribution in terms of the volume fraction of the constituents. The third order shear deformation theory (TSDT) to account for rotary inertia and transverse shear strains is adopted to formulate the theoretical model. The modal analysis technique is used to develop the analytic solutions of the dynamic problem. The effect of material compositions and temperature fields is examined. The present theoretical results are verified by comparing with those from finite element analysis by ANSYS.

크랭크 축의 모우드 해석에 관한 연구 (A study on modal analysis of a crankshaft)

  • 박윤식;제양규;오동엽
    • 오토저널
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    • 제7권4호
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    • pp.67-72
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    • 1985
  • An analytical and experimental modal analysis is carried out upon a crankshaft of a four cylinder internal combustion engine for studying dynamic characteristics of the shaft. Influence coefficient method is adopted in modelling the object and the calculated dynamic properties are directly compared with the experimentally obtained torsional and bending natural frequencies and mode shapes. It is found that the test results are well agree with the outputs from analytical model especially in low harmonics.

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