• Title/Summary/Keyword: Dynamics of Structural System

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A fast precise integration method for structural dynamics problems

  • Gao, Q.;Wu, F.;Zhang, H.W.;Zhong, W.X.;Howson, W.P.;Williams, F.W.
    • Structural Engineering and Mechanics
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    • v.43 no.1
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    • pp.1-13
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    • 2012
  • A fast precise integration method (FPIM) is proposed for solving structural dynamics problems. It is based on the original precise integration method (PIM) that utilizes the sparse nature of the system matrices and especially the physical features found in structural dynamics problems. A physical interpretation of the matrix exponential is given, which leads to an efficient algorithm for both its evaluation and subsequently the solution of large-scale structural dynamics problems. The proposed algorithm is accurate, efficient and requires less computer storage than previous techniques.

Recent Developments in Multibody Dynamics

  • Schiehlen Werner
    • Journal of Mechanical Science and Technology
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    • v.19 no.spc1
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    • pp.227-236
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    • 2005
  • Multibody system dynamics is based on classical mechanics and its engineering applications originating from mechanisms, gyroscopes, satellites and robots to biomechanics. Multibody system dynamics is characterized by algorithms or formalisms, respectively, ready for computer implementation. As a result simulation and animation are most convenient. Recent developments in multibody dynamics are identified as elastic or flexible systems, respectively, contact and impact problems, and actively controlled systems. Based on the history and recent activities in multibody dynamics, recursive algorithms are introduced and methods for dynamical analysis are presented. Linear and nonlinear engineering systems are analyzed by matrix methods, nonlinear dynamics approaches and simulation techniques. Applications are shown from low frequency vehicles dynamics including comfort and safety requirements to high frequency structural vibrations generating noise and sound, and from controlled limit cycles of mechanisms to periodic nonlinear oscillations of biped walkers. The fields of application are steadily increasing, in particular as multibody dynamics is considered as the basis of mechatronics.

Structural Dynamics Analyses of a 5MW Floating Offshore Wind-Turbine Using Equivalent Modeling Technique (등가모델링기법을 이용한 5MW급 부유식 해상용 풍력발전기 구조동역학해석)

  • Kim, Myung-Hwan;Kim, Dong-Hyun;Kim, Dong-Hwan;Kim, Bong-Yung
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2011.10a
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    • pp.614-622
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    • 2011
  • In this study, the computational structural dynamic modeling of floating offshore wind turbine system is presented using efficient equivalent modeling technique. Structural dynamic behaviors of the offshore floating platform with 5MW wind turbine system have been analyzed using computational multi-body dynamics based on the finite element method. The considered platform configuration of the present offshore wind turbine model is the typical spar-buoy type. Equivalent stiffness and damping properties of the floating platform were extracted from the results of the baseline model. Dynamic responses for the floating wind turbine models are presented and compared to investigate its structural dynamic characteristics. It is important shown that the results of the present equivalent modeling technique show good and reasonable agreements with those by the fully coupled analysis considering complex floating body dynamics.

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I-DEAS System Dynamics Analysis의 소개

  • 최상식
    • Computational Structural Engineering
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    • v.3 no.4
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    • pp.24-28
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    • 1990
  • I-DEAS System Dynamics Analysis는 컴퓨터에 의한 해석적 동특성 파악이 어려운 구조요소와 해석적 동특성 파악이 가능한 구조요소가 함께 결합되어 있는 복잡한 구조물에 대하여, 전자의 구조요소에 대해서는 실험에 의해 추출된 동특성을 후자의 구조요소에 대해서는 컴퓨터 해석에 의한 동특성을 사용하여 전체 구조 시스템에 대한 동적해석을 가능하게 하는 프로그램이다.

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NOISE REFINEMENT OF A VEHICLE BY REDUCTION OF THE AXLE GEAR WHINE NOISE BASED ON STRUCTURAL MODIFICATION USING FEM AND BEM

  • Kim, S.J.;Lee, J.Y.;Lee, S.K.
    • International Journal of Automotive Technology
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    • v.8 no.5
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    • pp.605-614
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    • 2007
  • This paper presents the research results for the reduction of a gear whine noise based on experimental and analytic methods. The test vehicle has a whine noise problem at the passenger seats in a sport utility vehicle. To identify the transfer path of the interior noise due to the axle system, a vibration path analysis, modal analysis and operational deflection shape analysis are systematically employed. By using these various methods, it has been found that the interior noise generated by the axle system was airborne noise. To reduce and predict the whine generated by the axle system, structural modifications for the axle system are performed by using FEM and BEM techniques. The structural modification of the axle cover is suggested for the reduction of whine noise.

Direct assignment of the dynamics of a laboratorial model using an active bracing system

  • Moutinho, C.;Cunha, A.;Caetano, E.
    • Smart Structures and Systems
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    • v.8 no.2
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    • pp.205-217
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    • 2011
  • This article describes the research work involving the implementation of an Active Bracing System aimed at the modification of the initial dynamics of a laboratorial building structure to a new desired dynamics. By means of an adequate control force it is possible to assign an entirely new dynamics to a system by moving its natural frequencies and damping ratios to different values with the purpose of achieving a better overall structural response to external loads. In Civil Engineering applications, the most common procedures for controlling vibrations in structures include changing natural frequencies in order to avoid resonance phenomena and increasing the damping ratios of the critical vibration modes. In this study, the actual implementation of an active system is demonstrated, which is able to perform such modifications in a wide frequency range; to this end, a plane frame physical model with 4 degrees-of-freedom is used. The Active Bracing System developed is actuated by a linear motor controlled by an algorithm based on pole assignment strategy. The efficiency of this control system is verified experimentally by analyzing the control effect obtained with the modification of the initial dynamic parameters of the plane frame and observing the subsequent structural response.

Multi-body Dynamics and Structural Vibration Analyses of Smart UAV Ground Test Equipment (스마트 무인기 지상시험장치의 다물체 동역학 및 구조진동해석)

  • Park, Kang-Kyun;Kim, Dong-Hyun;Kim, Dong-Man;Choi, Hyun-Chul;Ahn, Oh-Sung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.1
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    • pp.22-29
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    • 2010
  • In this study, computational multi-body dynamics and structural vibration analyses including some impact condition have been conducted for the ground flight test system of the developed smart UAV model. Designed ground test system has four degree-of-freedom motions with limited motion control mechanism. Design safety margin designs for several structural components are tested and verified considering expected critical motions (pitching and rolling) of the test smart UAV model. Computational results for various analysis conditions are practically presented in detail. Futhermore, proper design modifications of the initially designed test equipment in order to guarantee or increase structural safety have been successfully conducted in the design stage.

Co-author Network Characteristics of Korean System Dynamics Review (한국시스템다이내믹스 학회지 공저자 네트워크 특성에 관한 연구)

  • Kim, Sun-Duck;Sin, Cheol;Jung, Hyung-Ki;Lee, Man-Hyung
    • Korean System Dynamics Review
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    • v.17 no.3
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    • pp.31-50
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    • 2016
  • This study examines the basic conditions of joint authorship research activities in the Korean System Dynamics Review and points out the structural co-author network characteristics among co-authored papers based on the social network analysis(SNA) techniques. In specific, this study identifies the cooperative relationship of research papers in the Korean System Dynamics Review, knowledge formation, and knowledge propagation paths. The study results imply that Korean System Dynamics Review has exhibited the typical 'Steven's power law,' which is repeatedly observed among complex systems, and that knowledge structure centered upon and propagated around couples of researchers. Additionally, the study results present that there have been active personal exchanges among major researchers. In contrast, personal contacts among research groups and within groups seem relatively weak.

Metamodeling of nonlinear structural systems with parametric uncertainty subject to stochastic dynamic excitation

  • Spiridonakos, Minas D.;Chatzia, Eleni N.
    • Earthquakes and Structures
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    • v.8 no.4
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    • pp.915-934
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    • 2015
  • Within the context of Structural Health Monitoring (SHM), it is often the case that structural systems are described by uncertainty, both with respect to their parameters and the characteristics of the input loads. For the purposes of system identification, efficient modeling procedures are of the essence for a fast and reliable computation of structural response while taking these uncertainties into account. In this work, a reduced order metamodeling framework is introduced for the challenging case of nonlinear structural systems subjected to earthquake excitation. The introduced metamodeling method is based on Nonlinear AutoRegressive models with eXogenous input (NARX), able to describe nonlinear dynamics, which are moreover characterized by random parameters utilized for the description of the uncertainty propagation. These random parameters, which include characteristics of the input excitation, are expanded onto a suitably defined finite-dimensional Polynomial Chaos (PC) basis and thus the resulting representation is fully described through a small number of deterministic coefficients of projection. The effectiveness of the proposed PC-NARX method is illustrated through its implementation on the metamodeling of a five-storey shear frame model paradigm for response in the region of plasticity, i.e., outside the commonly addressed linear elastic region. The added contribution of the introduced scheme is the ability of the proposed methodology to incorporate uncertainty into the simulation. The results demonstrate the efficiency of the proposed methodology for accurate prediction and simulation of the numerical model dynamics with a vast reduction of the required computational toll.

Experimental investigation of an active mass damper system with time delay control algorithm

  • Jang, Dong-Doo;Park, Jeongsu;Jung, Hyung-Jo
    • Smart Structures and Systems
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    • v.15 no.3
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    • pp.863-879
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    • 2015
  • This paper experimentally investigates the effectiveness and applicability of the time delay control (TDC) algorithm, which is simple and robust to unknown system dynamics and disturbance, for an active mass damper (AMD) system to mitigate the excessive vibration of a building structure. To this end, the theoretical background including the mathematical formulation of the control system is first described; and then, a thorough experimental study using a shaking table system with a small-scale three-story building structural model is conducted. In the experimental tests, the performance of the proposed control system is examined by comparing its structural responses with those of the uncontrolled system in the free vibration and forced vibration cases. It is clearly verified from the test results that the TDC algorithm embedded AMD system can effectively reduce the structural response of the building structure.