• 제목/요약/키워드: Nonlinear Vibration Analysis

검색결과 685건 처리시간 0.022초

비선형 불규칙 진동 보의 등가에너지법에 의한 선형화 (Linearization of Nonlinear Random Vibration Beam by Equivalent Energy Method)

  • 이신영
    • 한국공작기계학회논문집
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    • 제17권1호
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    • pp.71-76
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    • 2008
  • Nonlinear dynamic system under random excitation was analyzed by using stochastic method. A linearization method was used in order to linearize non-linear structural characteristics but the parametric excitation was used as it was given. An equivalent energy method which equalizes the expectation value of energy of the original nonlinear system and that of quasi-linearized system was proposed. Ito's differential rule was applied to obtain steady state moments. Quasi-linearization coefficients can be obtained the iterative calculation of linearization scheme and steady state moments. Monte Carlo simulation was used to verify the results of the proposed method. Nonlinear vibration of a slender beam was analyzed in this research. The analysis results were compared with Monte Carlo simulation result and showed good agreement. As the spectral density of the given excitation increased, the analysis results showed the better agreement with Monte Carlo simulation.

A novel nonlinear gas-spring TMD for the seismic vibration control of a MDOF structure

  • Rong, Kunjie;Lu, Zheng
    • Structural Engineering and Mechanics
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    • 제83권1호
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    • pp.31-43
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    • 2022
  • A nonlinear gas-spring tuned mass damper is proposed to mitigate the seismic responses of the multi-degree-of-freedom (MDOF) structure, in which the nine-story benchmark model is selected as the controlled object. The nonlinear mechanical properties of the gas-spring are investigated through theoretical analysis and experiments, and the damper's control parameters are designed. The control performance and damping mechanism of the proposed damper attached to the MDOF structure are systematically studied, and its reliability is also explored by parameter sensitivity analysis. The results illustrate that the nonlinear gas-spring TMD can transfer the primary structure's vibration energy from the lower to the higher modes, and consume energy through its own relative movement. The proposed damper has excellent "Reconciling Control Performance", which not only has a comparable control effect as the linear TMD, but also has certain advantages in working stroke. Furthermore, the control parameters of the gas-spring TMD can be determined according to the external excitation amplitude and the gas-spring's initial volume.

Dynamic and reliability analysis of stochastic structure system using probabilistic finite element method

  • Moon, Byung-Young;Kang, Gyung-Ju;Kang, Beom-Soo;Cho, Dae-Seung
    • Structural Engineering and Mechanics
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    • 제18권1호
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    • pp.125-135
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    • 2004
  • Industrial structure systems may have nonlinearity, and are also sometimes exposed to the danger of random excitation. This paper proposes a method to analyze response and reliability design of a complex nonlinear structure system under random excitation. The nonlinear structure system which is subjected to random process is modeled by finite element method. The nonlinear equations are expanded sequentially using the perturbation theory. Then, the perturbed equations are solved in probabilistic methods. Several statistical properties of random process that are of interest in random vibration applications are reviewed in accordance with the nonlinear stochastic problem.

조합공진 영역에서 감쇠의 영향을 고려한 비선형 진동 응답 특성 (Nonlinear Oscillation Characteristics in Combination Resonance Region Considering Damping Effects)

  • 정태건
    • 한국소음진동공학회논문집
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    • 제20권9호
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    • pp.849-855
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    • 2010
  • Damping may change the response characteristics of nonlinear oscillations due to the parametric excitation of a thin cantilever beam. When the natural frequencies of the first bending and torsional modes are of the same order of magnitude, we can observe the one-to-one combination resonance in the perturbation analysis depending on the characteristic parameters. The nonlinear behavior about the combination resonance reveals a chaotic motion depending on the natural frequencies and damping ratio. We can analyze the chaotic dynamics by using the eigenvalue analysis of the perturbed components. In this paper, we derived the equations for autonomous system and solved them to obtain the characteristic equation. The stability analysis was carried out by examining the eigenvalues. Numerical integration gave the physical behavior of each mode for given parameters.

Hybrid nonlinear control of a tall tower with a pendulum absorber

  • Orlando, Diego;Goncalves, Paulo B.
    • Structural Engineering and Mechanics
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    • 제46권2호
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    • pp.153-177
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    • 2013
  • Pendulums can be used as passive vibration control devices in several structures and machines. In the present work, the nonlinear behavior of a pendulum-tower system is studied. The tower is modeled as a bar with variable cross-section with concentrated masses. First, the vibration modes and frequencies of the tower are obtained analytically. The primary structure and absorber together constitute a coupled system which is discretized as a two degrees of freedom nonlinear system, using the normalized eigenfunctions and the Rayleigh-Ritz method. The analysis shows the influence of the geometric nonlinearity of the pendulum absorber on the response of the tower. A parametric analysis also shows that, with an appropriate choice of the absorber parameters, a pendulum can decrease the vibration amplitudes of the tower in the main resonance region. The results also show that the pendulum nonlinearity cannot be neglected in this type of problem, leading to multiplicity of solutions, dynamic jumps and instability. In order to improve the effectiveness of the control during the transient response, a hybrid control system is suggested. The added control force is implemented as a non-linear variable stiffness device based on position and velocity feedback. The obtained results show that this strategy of nonlinear control is attractive, has a good potential and can be used to minimize the response of slender structures under various types of excitation.

상관차원에 의한 볼베어링 고장진단 (Fault Diagnosis of Ball Bearing using Correlation Dimension)

  • 김진수;최연선
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2004년도 춘계학술대회논문집
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    • pp.979-984
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    • 2004
  • The ball bearing having faults generally shows, nonlinear vibration characteristics. For the effective method of fault diagnosis on bail bearing, non-linear diagnostic methods can be used. In this paper, the correlation dimension analysis based on nonlinear timeseries was applied to diagnose the faults of ball bearing. The correlation dimension analysis shows some Intrinsic information of underlying dynamical systems, and clear the classification of the fault of ball bearing.

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회전하는 링의 비선형 진동해석 (Nonlinear Vibration Analysis of Rotating Ring)

  • 김선경;이수일;정진태
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2000년도 추계학술대회논문집
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    • pp.553-557
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    • 2000
  • Nonlinear Vibrations of a flexible circular ring is studied in this paper. Based upon the von Karman strain theory, the nonlinear governing equations are derived, in which the in-plane bending and extension displacements as well as the out-of-plane bending displacement are fully coupled. After discretizing the governing equations by the Galerkin approximation method, we obtain the linearlized equation by using the pertubation method. The analysis results from the linearlized equations show that the in-plane displacement has effects on the natural frequencies of the out-of-plane displacement.

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지진시 저층건물 면진구조의 비선형 동적 거동 (Dynamic Stability Analysis of Base-Isolated Low-level Nonlinear Structure Under Earthquake Excitation)

  • 문병영;강경주;강범수;김계수
    • 대한기계학회논문집A
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    • 제25권11호
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    • pp.1743-1750
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    • 2001
  • This paper presents an analysis of nonlinear response of the seismically isolated structure against earthquake excitation to evaluate isolation performances of a rubber bearing. In the analysis of the vibration of building, the building is modeled by lumped mass system where the restoring force is considered as linear, bilinear and trilinear. Fundamental equations of motion are derived for the base isolated structure, and hysteretic and nonlinear-elastic characteristics are considered for a numerical calculation. The excitation levels are magnified fur the recorded strong earthquake motions in order to examine dynamic stability of the structure. Seismic responses (of the building are compared fur the each restoring force type. As a result, it is shown that the effect of the motion by the nonlinear response of the building is comparatively not so large from a seismic design standpoint. The responses of the isolated structures reduce sufficiently and controled the motion of the building well in a practical range. By increasing the acceleration of the earthquake, the yielding of the farce was occurred in the concrete and steel frame, which shows the necessity of the exact nonlinear dynamic analysis.

비선형 강성을 고려한 밸브 모델의 진동 해석 (Vibration Analysis of a Valve Model with Nonlinear Stiffness)

  • 이수일;주재만;김태식;박윤서
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 1998년도 춘계학술대회논문집; 용평리조트 타워콘도, 21-22 May 1998
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    • pp.143-147
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    • 1998
  • In this study, nonlinear stiffness characteristics of a discharge valve in a small hermetic compressor was considered. It was approximated, with piecewise-linearity, and cubic or quintic nonlinearity by the static load-displacement experimental results. Based on the fluid-structure interaction effects and mass flow rate, the derived 1-DOF equation of motion for the valve model was analyzed. Finally, the dynamic response of the discharge valve was studied with parameters such as the ratio of the running frequency of the compressor to the linear natural frequency of the valve.

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