• 제목/요약/키워드: Nonlinear Vibration Analysis

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공동을 고려한 원주방향 급유홈 저널 베어링의 비선형 진동 해석 (Nonlinear Frequency Response Analysis of Circumferentially Grooved Journal Bearing Considering Cavitation)

  • 노병후;김경웅
    • 한국윤활학회:학술대회논문집
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    • 한국윤활학회 1999년도 제30회 추계학술대회
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    • pp.160-166
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    • 1999
  • Nonlinear characteristics of the hydrodynamic journal bearing with circumferentially groove are analyzed numerically considering cavitation region, when an external sinusoidal shock is given to the system. The oil film force is obtained by solving the finite width universal Reynolds equation at each time step. Frequency response function and journal orbit obtained from both linear and nonlinear bearing simulations are compared with each other. The vibration response of the journal is different from the expectation obtained from the linear analysis as increase the vibration amplitude of external disturbance. Therefore, the linear theory is not adequate, and the nonlinear calculation such as used in this research is needed to design safety rotor systems.

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Accurate analytical solution for nonlinear free vibration of beams

  • Bayat, M.;Pakar, I.
    • Structural Engineering and Mechanics
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    • 제43권3호
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    • pp.337-347
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    • 2012
  • In this study, Hamiltonian Approach (HA) is applied to analysis the nonlinear free vibration of beams. Two well-known examples are illustrated to show the efficiency of this method. One of them deals with the Nonlinear vibration of an electrostatically actuated microbeam and the other is the nonlinear vibrations of tapered beams. This new approach prepares us to achieve the beam's natural frequencies and mode shapes easily and a rapidly convergent sequence is obtained during the solution. The effects of the small parameters on the frequency of the beams are discussed. Some comparisons are conducted between the results obtained by the Hamiltonian Approach (HA) and numerical solutions using to illustrate the effectiveness and convenience of the proposed methods.

밸트 구동계의 비선형 진동 특성 해석 (Analysis on the Nonlinear Vibration Characteristics of a Belt Driven System)

  • 김성걸;이장무;이신영
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1994년도 추계학술대회 논문집
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    • pp.945-952
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    • 1994
  • In this paper, a mathematical model for a belt driven system is proposed to analyse the vibtation characteristics of the driving units with belts and the free and forced vibration analyses are carried out. The mathematical model for model for the belt-driven system includes belts,pulleys, spindle and bearings. Using the Hamilton principle, the 4 nonlinear governing equations and the 12 nonlinear boundary conditions are derived. To linearize and discretize the nonlinear govering equations and boundary conditions, the perturbation method and Galerkin method are used. Also, the free vibration analyses for the various parameters of the belt driven system, which are belt tension, belt length, material property of belt, belt speed and pulley mass are made. The forced vibration analyses of the system are made and the dynamic responses for the main parmeters are analysed with the belt driven system.

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충격파 및 구조비선형성을 고려한 미사일 조종면의 유체유발 진동특성 (Flow-Induced Vibration Characteristics of a Missile Control Surface Considering Shock Wave and Structural Nonlinearity)

  • Kim, Dong-Hyun;Lee, In;Kim, Seung-Ho
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2002년도 추계학술대회논문초록집
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    • pp.389.2-389
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    • 2002
  • Nonlinear aeroelastic characteristics of a missile control surface are investigated in this study. The wing model has freeplay structural nonlinearity at its pitch axis. Nonlinear aerodynamic flows with unsteady shock waves are also considered in high-speed flow region. To effectively consider a freeplay structural nonlinearity, the fictitious mass method (FMM) is applied to structural vibration analysis based on finite element method (FEM). (omitted)

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탄소나노튜브 디바이스의 전기역학적 비선형 거동 해석 (Nonlinear Analysis of Electromechanical Behavior in Carbon Nanotube Devices)

  • 김일광;이수일;강상욱
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2009년도 추계학술대회 논문집
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    • pp.467-471
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    • 2009
  • In this study a cantilevered carbon nanotube(CNT) switch was investigated with the linear and the nonlinear structural models incorporating the electrostatic force and van der Waals interactions between the CNT and ground surface. Due to the applied voltage and van der Waals interactions the CNT deforms statically and dynamically and finally pull into the surface. When the nonlinear model is considered in case of the relatively large gap between the CNT and the surface, the static pull-in voltage was increased due to the nonlinear hardening effect. Also the dynamic response was investigated with the different external dc and ac voltages. The CNT shows various dynamic behaviors and instabilities including dynamic pull-in. Based on this study, further research on the dynamic and nonlinear stability of CNT nanodevices should be requested to develop the new type of nano switches or nano-memory.

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Nonlinear free and forced vibration analysis of microbeams resting on the nonlinear orthotropic visco-Pasternak foundation with different boundary conditions

  • Arani, Ali Ghorbanpour;Kiani, Farhad
    • Steel and Composite Structures
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    • 제28권2호
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    • pp.149-165
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    • 2018
  • Using the modified couple stress theory and Euler-Bernoulli beam theory, this paper studies nonlinear vibration analysis of microbeams resting on the nonlinear orthotropic visco-Pasternak foundation. Using the Hamilton's principle, the set of the governing equations are derived and solved numerically using differential quadrature method (DQM), Newark beta method and arc-length technique for all kind of the boundary conditions. First convergence and accuracy of the presented solution are demonstrated and then effects of radius of gyration, Poisson's ratio, small scale parameters, temperature changes and coefficients of the foundation on the linear and nonlinear natural frequencies and dynamic response of the microbeam are investigated.

에너지 소산형 감쇠기를 이용한 철근콘크리트 전단벽-골조 시스템의 진동제어 (Vibration Control of Shear Wall-Frame System using Energy Dissipation Devices)

  • 박지훈;김길환
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2007년도 춘계학술대회논문집
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    • pp.578-581
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    • 2007
  • In this study, the seismic control performance of energy dissipation devices installed in a shear all-frame structure is investigated through nonlinear time history analysis of a 12-story building. Inelastic shear walls are modeled using the multiple vertical line element model (MVLEM) and inelastic columns and girders were modeled using fiber beam elements. For a seismic load increased by 38% compared to the design load, the seismic control performance was analyzed based on the results of a nonlinear time history analysis in terms of the inter-story drift, the story shear and the flexural strain. Friction type dampers was found to performs best if they are installed in the form of a brace adjacent to the shear wall with the friction force of 15 % of the maximum story shear force induced in the original building structure without dampers.

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끝단 장착물이 있는 항공기 날개의 천음속/초음속 플러터 해석 (Transonic/Supersonic Flutter Analysis of a Fighter Wing with Tip-Store)

  • 김동현;이인
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 춘계학술대회논문집
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    • pp.1198-1203
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    • 2000
  • In this study, a nonlinear aeroelastic analysis system for the fighter wing with tip-store has been developed additionally in the transonic and supersonic flow region. The unsteady CFD code based on the transonic small disturbance theory has been incorporated to consider the numerical capability for the aerodynamic nonlinear effects. The coupled time-integration method is used to observe the detailed nonlinear aeroelastic responses for elastic wings in their flight. condition. A conservative wing-box model of a fighter wing with tip-store is modeled by MSC/PATRAN and the corresponding free vibration analysis has been performed by MSC/NASTRAN. The results of flutter analyses are presented in the subsonic, transonic and supersonic flow regime.

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비원형 단면의 선삭 가공시 발생하는 진동해석 (Vibration Analysis of a Lathe Performing Non-Circular Cutting)

  • 신응수;박정호
    • 소음진동
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    • 제10권2호
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    • pp.291-298
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    • 2000
  • This paper intends to provide an analytic vibrational model of non-circular cutting by a lathe and to investigate its stability criteria. A single degree-of-freedon model based on the orthogonal cutting theory has the characteristics of parametric excitation due to the nonlinear cutting force that changes periodically its direction as well as its magnitude. The Floquet theory has been applied to investigate the stability of the linearized system and the stability diagrams have been obtained with respect to the ovality, the cut velocity and the cut depth. Also nonlinear analysis has been performed to verify the linear analysis and compare the results with those from circular cutting. Results show that a critical cut depth is decreased as the ovality is increased while a critical cut velocity is increased as the ovality is increased. Also, a good agreement in critical conditions has been observed between the linear and nonlinear analyses for the ovality less than 2%. Accordingly, the linear analysis can be said to be applicable for most practical oval cuttings whose ovality are much less than 2%.

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Nonlinear thermal vibration of pre/post-buckled two-dimensional FGM tapered microbeams based on a higher order shear deformation theory

  • Hendi, Asmaa A.;Eltaher, Mohamed A.;Mohamed, Salwa A.;Attia, Mohamed A.;Abdalla, A.W.
    • Steel and Composite Structures
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    • 제41권6호
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    • pp.787-803
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    • 2021
  • The size-dependent nonlinear thermomechanical vibration analysis of pre- and post-buckled tapered two-directional functionally graded (2D-FG) microbeams is presented in this study. In the context of the modified couple stress theory, the formulations are derived based on the parabolic shear deformation beam theory and von Karman nonlinear strains. Different thermomechanical material properties are assumed to be temperature-dependent and smoothly vary in both length and thickness directions using the power law and the physical neutral axis concept is employed. The nonlinear governing equations are derived using the Hamilton principle and the resulting variable coefficient equations of motion are solved using the differential quadrature method (DQM) and iterative Newton's method for clamped-clamped and simply supported boundary conditions. Comparison studies are presented to validate the derived model and solution procedure. The impacts of induced thermal moments, temperature power index, two gradient indices, nonuniform cross-section, and microstructure length scale parameter on the frequency-temperature configurations are explored for both clamped and simply supported microbeams.