• 제목/요약/키워드: Dynamic coordinate system

검색결과 212건 처리시간 0.03초

트랙좌표계를 이용한 철도차량의 동역학 해석에 관한 연구 (A Study on the Dynamic Analysis of Railway Vehicle by Using Track Coordinate System)

  • 강주석
    • 한국자동차공학회논문집
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    • 제21권2호
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    • pp.122-130
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    • 2013
  • Rail geometries such as cant, grade and curvature can be easily represented by means of a track coordinate system. In this analysis, in order to derive a dynamic and constraint equation of a wheelset, the track coordinate system is used as an intermediate stage. Dynamic and constraint equations of railway vehicle bodies except the wheelset are written in the Cartesian coordinate system as a conventional method. Therefore, whole dynamic equations of a railway vehicle are derived by combining wheelset dynamic equations and dynamic equations of railway vehicle bodies. Constraint equations and constraint Jacobians are newly derived for the track coordinate system. A process for numerical analysis is suggested for the derived dynamic and constraint equations of a railway vehicle. The proposed dynamic analysis of a railway vehicle is validated by comparison against results obtained from VI-RAIL analysis.

절대절점좌표를 이용한 탄성 다물체동역학 해석에서의 동응력 이력 계산에 관한 연구 (Computation of Dynamic Stress in Flexible Multi-body Dynamics Using Absolute Nodal Coordinate Formulation)

  • 서종휘;정일호;박태원
    • 한국정밀공학회지
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    • 제21권5호
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    • pp.114-121
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    • 2004
  • Recently, the finite element absolute nodal coordinate formulation (ANCF) was developed for the large deformation analysis of flexible bodies in multi-body dynamics. This formulation is based on the finite element procedures and the general continuum mechanics theory to represent the elastic forces. In this paper, a computation method of dynamic stress in flexible multi-body dynamics using absolute nodal coordinate formulation is proposed. Numerical examples, based on an Euler-Bernoulli beam theory, are shown to verify the efficiency of the proposed method. This method can be applied for predicting the fatigue life of a mechanical system. Moreover, this study demonstrates that structural and multi-body dynamic models can be unified in one numerical system.

차세대 고속철도 시스템해석을 위한 동역학 솔버 플랫폼 개발 (Development of a Dynamic Solver Platform for the Next Generation Railway Vehicle)

  • 윤지원;박태원;정성필;박성문;김영국;김영모
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2008년도 춘계학술대회 논문집
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    • pp.913-918
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    • 2008
  • When developing railway vehicle system, investigation of the dynamical stability is essential as a virtual prototyping process. Not only the verification using the commercial analysis tools, systematic analysis using customized tools is also necessary, because these can give other points of view in stability, which is sometimes unable to evaluate in the former one. As a solver platform for customization, it is important to derive basic theory about flexible bodies and build flexible structure, which enables easy module insertion of user-created functions. In the paper, a flexible dynamic analysis system is developed, using absolute cartesian coordinate, modal coordinate and absolute nodal coordinate. Each coordinate system is verified by respective examples for every system. This solver system will play an important role for building the basic platform for analysis system, keeping pace with the concurrent development of the modules, such as wheel-contact force, constraints and user-defined force modules. Using the information from the analysis, the evaluation of the dynamic behavior of the train and its stability analysis will be available.

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On the Modeling of Dynamic Systems

  • Suk, Jinyoung;Kim, Youdan
    • International Journal of Aeronautical and Space Sciences
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    • 제2권1호
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    • pp.78-92
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    • 2001
  • In this paper, several dynamic systems are modeled using the time domain finite element method. Galerkins' Weak Principle is used to model the general second-order mechanical system, and is applied to a simple pendulum dynamics. Problems caused by approximating the final momentum are also investigated. Extending the research, some dynamic analysis methods are suggested for the hybrid coordinate systems that have both slew and flexible modes. The proposed methods are based on both Extended Hamilton's Principle and Galerkin's Weak Principle. The matrix wave equation is propagated in space domain, satisfying the geometric/natural boundary conditions. As a result, the flexible motion can be obtained compatible with the applied control input. Numerical example is shown to demonstrate the effectiveness of the proposed modeling methods for the hybrid coordinate systems.

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Large eddy simulation using a curvilinear coordinate system for the flow around a square cylinder

  • Ono, Yoshiyuki;Tamura, Tetsuro
    • Wind and Structures
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    • 제5권2_3_4호
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    • pp.369-378
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    • 2002
  • The application of Large Eddy Simulation (LES) in a curvilinear coordinate system to the flow around a square cylinder is presented. In order to obtain sufficient resolution near the side of the cylinder, we use an O-type grid. Even with a curvilinear coordinate system, it is difficult to avoid the numerical oscillation arising in high-Reynolds-number flows past a bluff body, without using an extremely fine grid used. An upwind scheme has the effect of removing the numerical oscillations, but, it is accompanied by numerical dissipation that is a kind of an additional sub-grid scale effect. Firstly, we investigate the effect of numerical dissipation on the computational results in a case where turbulent dissipation is removed in order to clarify the differences between the effect of numerical dissipation. Next, the applicability and the limitations of the present method, which combine the dynamic SGS model with acceptable numerical dissipation, are discussed.

탄성 다물체계에 대한 조인트좌표 공간에서의 역동역학 해석 (Inverse Dynamic Analysis of Flexible Multibody System in the Joint Coordinate Space)

  • 이병훈
    • 대한기계학회논문집A
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    • 제21권2호
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    • pp.352-360
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    • 1997
  • An inverse dynamic procedure for spatial multibody systems containing flexible bodies is developed in the relative joint coordinate space. Constraint acceleration equations are derived in terms of relative coordinates using the velocity transformation technique. An inverse velocity transformation operator, which transforms the Cartesian velocities to the relative velocities, is derived systematically corresponding to the types of kinematic joints connecting the bodies and the system reference matrix. Using the resulting matrix, the joint reaction forces and moments are analyzed in the Cartesian coordinate space. The formulation is illustrated by means of two numerical examples.

상대 이음 좌표 방법을 이용한 링키지 메카니즘에 대한 동역학적 해석에 관한 연구

  • 이동찬;배대성;한창수
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1992년도 추계학술대회 논문집
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    • pp.339-343
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    • 1992
  • For the analysis of dynamic behavior of dynamic behavior of multibody systems by cartesian coordinate method, maximal sets of generalized coordinates and maximum numbers of differential equation and constraints must be considered. Therefore the inefficiency of the increase of CPU time is occurred. This paper is to analyze the dynamic system by using the relative coordinate method without violating the geometric condition of systems. The graph theory and system topology were used for this study. The dynamic systems could be analyzed by the automatic generation of the informations like equation of motion, constraints, and external forces etc. And the results were compared and verified with dynamic commercial package DADS.

자동차 와이퍼 시스템의 유연 다물체 동역학 해석 (Flexible Multibody Dynamic Analysis of the Wiper System for Automotives)

  • 정성필;박태원;정원선
    • 대한기계학회논문집A
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    • 제34권2호
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    • pp.175-181
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    • 2010
  • 본 논문에서는 플랫 타입 블레이드를 장착한 와이퍼 시스템의 성능을 예측하기 위한 동역학 해석방법을 제시하였다. 고무 재질로 이루어진 블레이드는 비선형의 특성을 갖기 때문에, 블레이드의 동적특성을 나타내기 위하여 모달 좌표계와 절대 절점 좌표계를 이용하였다. 블레이드 단면의 굽힘 특성을 파악하기 위해 블레이드에 대한 구조 해석을 실시하였다. 해석 결과에 따라 블레이드 단면을 강체, 유연체 및 대변형체의 3 부분으로 구분하였다. 모달 좌표계와 절대 절점 좌표계를 이용하여 블레이드 단면의 유연체 및 대변형체를 표현하였다. 동역학 해석 결과를 검증하기 위해 실험을 실시하였고, 결과 비교를 통해 본 연구에서 생성한 블레이드에 대한 유연 다물체 모델의 신뢰성을 검증하였다.

삼중레이스를 갖는 자동평형장치의 동적 해석 (Dynamic Analysis of an Automatic Ball Balancer with Triple Races)

  • 좌성훈;조은형;손진승;박준민;정진태
    • 대한기계학회논문집A
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    • 제26권4호
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    • pp.764-774
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    • 2002
  • Dynamic behaviors are analyzed for an automatic ball balancer (ABB) with triple races, which is a device to reduce the unbalanced mass of optical disk drives (ODD) such as CD-ROM or DVD drives. The nonlinear equations of motion are derived by using Lagrange's equations with the polar coordinate system. It is shown that the polar coordinate system provides the complete stability analysis while the rectangular coordinate system used in other previous studies has limitations on the stability analysis. For the stability analysis, the equilibrium positions and the linearized perturbation equations are obtained by the perturbation method. Based on the linearized equations, the stability of the system is analyzed around the equilibrium positions; furthermore, to confirm the stability, the time responses for the nonlinear equations of motion are computed by using a time integration method and experimental analyses are performed. Theoretical and experimental results show a superiority of the ABB with triple races.

회전기계의 진동저감을 위한 자동볼평형장치 (Automatic Ball Balancer for Vibration Reduction of Rotating Machines)

  • 정진태
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2005년도 춘계학술대회논문집
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    • pp.59-68
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    • 2005
  • In this study, we establish a theory for dynamic behaviors of an automatic ball balancer, analyze its dynamic characteristics, and provide its design guide line. Equations of motion are derived by using the polar coordinate system instead of the rectangular coordinate system which was previously used in other researches. After non-dimensionalization of the equations, the perturbation method is applied to locate the equilibrium positions and to obtain the linearized equations of motion around the equilibrium positions. The Eigenvalue problem is used to verify the dynamic stability around the equilibrium positions. On the other hand, the time responses are computed from the nonlinear equations of motion by using a time integration method.

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