• Title/Summary/Keyword: Rigid Body Mode

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Vibration Analysis of a Flexible Structure in a Motion (유연 구조물의 운동중 발생하는 진동의 해석)

  • 이신영
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.6
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    • pp.1503-1509
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    • 1994
  • An analysis method is suggested and experimentally studied in order to solve a vibration problem of a flexible structure while it is moving. In this method, substructure synthesis method, modal analysis method and Newmark's integral method were used. Total deformation of a structure was composed of quasistatic component and dynamic component. Rigid body modes were considered in calculation of dynamic component. Combining those two component, deformation behavior and a real structural model of a transfer feeder showed good agreements with computational results.

Development of Efficient Seismic Analysis Model using 3D Rigid-body for Wall-Frame Structures with an Eccentric Core (삼차원 T형강체를 이용한 편심코어를 가진 전단벽-골조 구조물의 효율적인 지진해석모델 개발)

  • Park, Yong-Koo;Lee, Dong-Guen;Kim, Hyun-Su
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.26 no.1
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    • pp.19-28
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    • 2013
  • In a shear wall-frame structural system, the structural response is determined by the interaction between the shear wall in bending mode and the frame in shear mode. In order to effectively consider these characteristics of a shear wall-frame structure, the simplified numerical model using the T-shape rigid body was suggested in the previous study. Based on the previously proposed model, an efficient numerical model for a wall-frame structure with an eccentric core has been proposed in this study. To this end, the previously proposed 2D model is extended to the 3D model and it is enhanced by considering torsion effects. As a result, the enhanced model can be applied to the analysis of a wall-frame structure with an eccentric core as well as a centric core.

Dynamic Modeling and Design of Controller based on Thrusters for Korean Lunar Module (달 착륙선의 동역학 모델링 및 추력기 기반 제어기 설계)

  • Yang, Sung-Wook;Lee, Sang-Chul
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.23 no.1
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    • pp.49-55
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    • 2015
  • This paper deals with dynamic modeling and controller design of a future Korean lunar module planned to be launched 2020's in Korea. For dynamic modeling of the lunar module, we first assume the lunar module as a rigid body. And we derive equations of motion for the lunar module by considering allocation of main thrusters and reaction thrusters. With the equation of motion, we design the controller based on the quaternion. A Pulse Width Pulse Frequency modulator(PWPFM) is selected for generating on/off signal. Finally, we construct a 2-phase descent mode including initial guidance mode, terminal guidance mode. The MATLAB simulation is performed for evaluating the descent ability and final landing velocity. The dynamic modeling and descent simulation of the lunar module in this paper could be applied for developing the future work of the Korean lunar exploration program.

A full path assessment approach for vibration serviceability and vibration control of footbridges

  • Zhu, Qiankun;Hui, Xiaoli;Du, Yongfeng;Zhang, Qiong
    • Structural Engineering and Mechanics
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    • v.70 no.6
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    • pp.765-779
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    • 2019
  • Most of the existing evaluation criteria of vibration serviceability rely on the peak acceleration of the structure rather than that of the people keeping their own body unmoved on the structure who is the real receiver of structural vibrations. In order to accurately assess the vibration serviceability, therefore, a full path assessment approach of vibration serviceability based on vibration source, path and receiver is not only tentatively proposed in this paper, taking the peak acceleration of receiver into account, but also introduce a probability procedure to provide more instructive information instead of a single value. In fact, semi-rigid supported on both sides of the structure is more consistent with the actual situation than simply supported or clamped due to the application of the prefabricated footbridge structures. So, the footbridge is regarded as a beam with semi-rigid supported on both sides in this paper. The differential quadrature-integral quadrature coupled method is not only to handle different type of boundary conditions, but also after being further modified via the introduction of an approximation procedure in this work, the time-varying system problem caused by human-structure interaction can be solved well. The analytical results of numerical simulations demonstrate that the modified differential quadrature-integral quadrature coupled method has higher reliability and accuracy compared with the mode superposition method. What's more, both of the two different passive control measures, the tuned mass damper and semi-rigid supported, have good performance for reducing vibrations. Most importantly, semi-rigid supported is easier to achieve the objective of reducing vibration compared with tuned mass damper in design stage of structure.

A Robust Control Approach for Maneuvering a Flexible Spacecraft

  • Sung, Yoon-Gyeoung;Lee, Jea-Won;Kim, Hunmo
    • Journal of Mechanical Science and Technology
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    • v.15 no.2
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    • pp.143-151
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    • 2001
  • In the paper, a robust control mechanism is presented to maneuver a flexible spacecraft with the deflection reduction during large slewing operation at the same time. For deflection reduction and maneuvering of the flexible spacecraft, a control mechanism is developed with the application of stochastic optimal sliding-mode control, a linear tracking model and input shaping technique. A start-coast-stop maneuver is employed as a slewing strategy. It is shown that the control mechanism with he strategic maneuver results in better performance and is more efficient than rigid-body-like maneuver, by applying to the Spacecraft Control Laboratory Experiment (SCOLE) system in a space environment.

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Improvement of Finite Element for Mindlin Plate Bending (Mindlin 평판 유한요소의 개선)

  • 김선훈;최창근
    • Computational Structural Engineering
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    • v.1 no.2
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    • pp.83-90
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    • 1988
  • The present work is concerned with the improvement of finite element for the analysis of plate bending structures. The element formulation is based upon Mindlin plate concept. The displacement field of this element is formed by adding nonconforming modes to two rotational displacement components of a 'heterosis plate element. The element has the requisite numbers of zero eigenvalues associated with rigid body modes to avoid the spurious zero energy mode. It is shown that the results obtained by the element converged to the exact solutions very rapidly as the mesh is refined and exhibited reliable solutions through numerical studies for standard benchmark problems. This element is shown to overcome the shear locking problem completely in very thin plate situation even for irregular meshes.

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Analysis and Control of the Flexible Multibody System Using MATLAB (MATLAB을 이용한 유연 다물체 시스템의 해석 및 제어)

  • Jung, Sung-Pil;Park, Tae-Won
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.5
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    • pp.437-443
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    • 2008
  • In this paper, analysis and control of the flexible multibody system using MATLAB is presented. The equations of motion of a flexible body are derived in terms of the modal coordinate. The rigid-flexible multibody dynamic solver is developed. Finite element information required to analyze motion of flexible bodies is imported from ANSYS. The modified finite element data, such as modal mass matrix, modal stiffness matrix and constraint mode shapes, is calculated in the solver. Since the solver is developed using MATLAB, it is very easy to connect with SIMULINK which is widely used to control motion of the multibody system. Several simulations are implemented to verify the developed solver. A control example is carried out and the usefulness of the developed solver is demonstrated.

Vibration Control of a Single-Link Flexible Manipulator Using Reaction Moment Estimator (반력모멘트 추정기를 이용한 단일 링크 유연 조작기의 진동제어)

  • Shin, Hocheol;Han, Sangsoo;Kim, Seungho
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.15 no.2 s.95
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    • pp.169-175
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    • 2005
  • In this paper, a novel vibration control scheme for a single-link flexible manipulator system without using a vibration feedback sensor is proposed. In order to achieve the vibration information of the flexible link, a reaction moment estimator based on the dynamic characteristics of the flexible manipulator is proposed. While the manipulator is maneuvering the reaction moment is reciprocally acting on the flexible link and the hub inertia due to the vibration of the link. A sliding mode controller based on the equivalent rigid body dynamics corresponding to the proposed flexible manipulator is then augmented with the reaction moment estimator to realize a decentralized control system. The reaction moment estimator is implemented via the first order low pass filter. The performance of the proposed control scheme is verified by computer simulation and experiment.

Dynamic Modeling of Washing System with Elastic Motion (탄성 운동을 고려한 세탁기 시스템의 동력학 모델링)

  • 오혁진;이우식
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2003.10a
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    • pp.47-54
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    • 2003
  • The rotating of rotatory unit with its structural unbalance mass and laundry is making the main vibration problem in a vertical axis washing machine. For reducing vibration problem total washing system hung on the case by its suspension system which is constitute of spring, damper and suspension bar and hydraulic balancer is attached at the upper rim of spin basket. In this paper, we make the dynamic model of washing system of its rigid body motions by 6 degree of freedoms. Hydraulic balancer is modeled by one degree of freedom like auto ball balancer. Elastic motions of washing system have found by method of analytic, experimental and FEM. And we consider first bending mode of each suspension bar and first circumferential mode of assy tub. So, the total washing system is modeled by 12 degree of freedoms. Equations of motion for total washing system have derived, and we perform the dynamic simulation tests.

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Sliding Mode Controller Design for Biped Robot (이족보행로봇을 위한 슬라이딩 제어기 설계)

  • Park, In-Gyu;Kim, Jin-Geol;Kim, Ki-Sik
    • Journal of the Korean Society for Precision Engineering
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    • v.18 no.5
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    • pp.137-146
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    • 2001
  • A robust controller with the sliding mode is proposed for stable dynamic walking of the biped robot in this paper. For the robot system to be controlled, which is modeled as 14 DOF rigid bodies by the method of multi-body dynamics, the joint angle trajectories are determined by the velocity transformation matrix. Also Hertz force model and Hysteresis damping element are utilized for the ground reaction and impact forces during the contact with the ground. The biped robot system becomes unstable since those forces contain highly confused noise components and some discontinuity, and modeling uncertainties such as parameter inaccuracies. The sliding mode control is applied to solve above problems. Under the assumption of the bounded estimation errors on the unknown parameters, the proposed controller provides a successful way to achieve the stability and good performance in spite of the presence of modeling imprecisions of uncertainties.

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