• Title/Summary/Keyword: Multibody systems

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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.

Selection of efficient coordinate partitioning methods in flexible multibody systems (탄성 시스템에서의 효율적인 좌표분할법 선정에 관한 연구)

  • Kim, Oe-Jo;Yoo, Wan-Suk
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.21 no.8
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    • pp.1311-1321
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    • 1997
  • In multibody dynamics, differential and algebraic equations which can satisfy both equation of motion and kinematic constraint equation should be solved. To solve these equations, coordinate partitioning method and constraint stabilization method are commonly used. In the coordinate partitioning method, the coordinates are divided into independent and dependent and coordinates. The most typical coordinate partitioning method are LU decomposition, QR decomposition, and SVD (singular value decomposition). The objective of this research is to find an efficient coordinate partitioning method in the dynamic analysis of flexible multibody systems. Comparing two coordinate partitioning methods, i.e. LU and QR decomposition in the flexible multibody systems, a new hybrid coordinate partitioning method is suggested for the flexible multibody analysis.

Modal Analysis of Constrained Multibody Systems Undergoing Constant Accelerated Motions

  • Park, Dong-Hwan;Yoo, Hong-Hee
    • Journal of Mechanical Science and Technology
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    • v.18 no.7
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    • pp.1086-1093
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    • 2004
  • The modal characteristics of constrained multibody systems undergoing constant accelerated motions are investigated in this paper. Relative coordinates are employed to derive the equations of motion, which are generally nonlinear in terms of the coordinates. The dynamic equilibrium position of a constrained multibody system needs to be obtained from the nonlinear equations of motion, which are then linearized at the dynamic equilibrium position. The mass and the stiffness matrices for the modal analysis can be obtained from the linearized equations of motion. To verify the effectiveness and the accuracy of the proposed method, two numerical examples are solved and the results obtained by using the proposed method are compared with those obtained by analytical and other numerical methods. The proposed method is found to be accurate as well as effective in predicting the modal characteristics of constrained multibody systems undergoing constant accelerated motions.

A Study on the Method for Dynamic Response Analysis in Frequency Domain of an Offshore Wind Turbine by Linearization of Equations of Motion for Multibody (다물체계 운동 방정식 선형화를 통한 해상 풍력 발전기 동적 거동의 주파수 영역 해석 방법에 관한 연구)

  • Ku, Namkug;Roh, Myung-Il;Ha, Sol;Shin, Hyun-Kyoung
    • Korean Journal of Computational Design and Engineering
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    • v.20 no.1
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    • pp.84-92
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    • 2015
  • In this study, we describe a method to analysis dynamic behavior of an offshore wind turbine in the frequency domain and expected effects of the method. An offshore wind turbine, which is composed of platform, tower, nacelle, hubs, and blades, can be considered as multibody systems. In general, the dynamic analysis of multibody systems are carried out in the time domain, because the equations of motion derived based on the multibody dynamics are generally nonlinear differential equations. However, analyzing the dynamic behavior in time domain takes longer than in frequency domain. In this study, therefore, we describe how to analysis the system multibody systems in the frequency domain. For the frequency domain analysis, the non-linear differential equations are linearized using total derivative and Taylor series expansions, and then the linearized equations are solved in time domain. This method was applied to analysis of double pendulum system for the verification of its effectiveness, and the equations of motion for the offshore wind turbine was derived with assuming that the wind turbine is rigid multibody systems. Using this method, the dynamic behavior analysis of the offshore wind turbine can be expected to take less time.

Development of a Internet-based Dynamic Simulation System for Multibody Systems (인터넷 기반 범용 다물체 동역학 시뮬레이션 시스템 개발)

  • Lee, Jai-Kyung;Han, Hyung-Suk;Seo, Jong-Whi;Park, Tae-Won
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.699-704
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    • 2003
  • A Internet-based dynamic simulation system, called P-DYN, for multibody dynamic systems is developed. All the interfaces of the system are accessible via Web browsers, such as Netscape or Explorer. The system uses a template type P-DYN/Modeler as a preprocessor. The P-DYN postprocessor composed of P-DYN/Plotter and P-DYN/Animator is developed in JAVA. The P-DYN/Solver for predicting the dynamic behavior is run on the server. Anyone who wants to simulate the dynamics of multibody systems or share results data can access the analysis system over the Internet regardless of their OS, platform, or location.

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Inverse Dynamic Analysis of Constrained Multibody Systems Considering Friction Forces on Kinematic Joints (기구학적 조인트에서 마찰력을 고려한 구속 다물체계의 역동역학 해석)

  • Park, Jeong-Hun;Yu, Hong-Hui;Hwang, Yo-Ha;Bae, Dae-Seong
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.8 s.179
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    • pp.2050-2058
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    • 2000
  • A method for the inverse dynamic analysis of constrained multibody systems considering friction forces acting on kinematic joints is presented in this paper. The stiction and the sliding which represent zero and non-zero relative motions are considered during the inverse dynamic analysis. Actuating forces to control the position or the orientation of constrained multibody systems are usually calculated in the inverse dynamic analysis. An iterative procedure need to be employed to calculate the actuating forces when the friction is considered. Furthermore, the actuating forces are not uniquely determined during the stiction. These difficulties are resolved by the method presented in this paper.

Development of a Web-based Dynamic Simulation System for Multibody Systems (웹기반 범용 다물체 동역학 시뮬레이션 시스템 개발)

  • 한형석;이재경
    • Journal of the Korean Society for Precision Engineering
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    • v.20 no.8
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    • pp.194-204
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    • 2003
  • A Web-based dynamic simulation system, called O-DYN, for multibody dynamic systems is developed. All the interfaces of the system are accessible via Web browsers, such as Netscape or Explorer. The system uses a block-diagram type O-DYN/Modeler developed in JAVA Applet as a preprocessor. The O-DYN postprocessor composed of O-DYN/Plotter and O-DYN/Animator is developed in JAVA Applet. The O-DYN/Solver for predicting the dynamic behavior is run on the server. Anyone who wants to simulate the dynamics of multibody systems or share results data can access the analysis system over the Internet regardless of their OS, platform, or location.

Web-based Simulation System for Multibody Systems

  • Han, Hyung-Suk
    • International Journal of Precision Engineering and Manufacturing
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    • v.4 no.6
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    • pp.50-60
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    • 2003
  • A web-based dynamic simulation system, called O-DYN, for multibody systems is developed. All the interfaces of the system are accessible via web browsers, such as Netscape or Explorer. The system uses a block-diagram type O-DYN/Modeler developed in JAVA Applet as a preprocessor. The O-DYN postprocessor composed of O-DYN/Plotter and O-DYN/Animator is developed in JAVA Applet. The O-DYN/Solver for predicting the dynamic behavior is run on the web server. Anyone who wants to simulate the dynamics of multibody systems or share results data can access the analysis system over the internet regardless of their OS, platform, or location.

Inverse Dynamic Analysis of Flexible Multibody Systems with Closed-Loops

  • Lee, Byung-Hoon;Lee, Shi-Bok;Jeong, Weui-Bong;Yoo, Wan-Suk;Yang, Jin-Saeng
    • Journal of Mechanical Science and Technology
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    • v.15 no.6
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    • pp.693-698
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    • 2001
  • The analysis of actuating forces (or torques) and joint reaction forces (or moments) are essential to determine the capacity of actuators, to control the system and to design the components. This paper presents an inverse dynamic analysis algorithm for flexible multibody systems with closed-loops in the relative joint coordinate space. The joint reaction forces are analyzed in Cartesian coordinate space using the inverse velocity transformation technique. The joint coordinates and the deformation modal coordinates are used as the generalized coordinates of a flexible multibody system. The algorithm is verified through the analysis of a slider-crank mechanism.

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A Time Integration Method for Analysis of Dynamic Systems Using Domain Decomposition Technique

  • Fujikawa Takeshi;Imanishi Etsujiro
    • Journal of Mechanical Science and Technology
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    • v.19 no.spc1
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    • pp.429-436
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    • 2005
  • This paper presents a precise and stable time integration method for dynamic analysis of vibration or multibody systems. A total system is divided into several subsystems and their responses are calculated separately, while the coupling effect is treated equivalently as constant force during time steps. By using iterative procedure to improve equivalent coupling forces, a precise and stable solution is obtained. Some examples such as a seismic response and multibody analyses were carried out to demonstrate its usefulness.