• Title/Summary/Keyword: Multibody System

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A Study on the Simulation of Operational Characteristics of Industrial Robot for Automated Manufacturing System (생산자동화 시스템을 위한 산업용 로봇의 운전특성 시뮬레이션에 관한 연구)

  • Kim, Jin-Kwang
    • Journal of the Korean Society of Industry Convergence
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    • v.20 no.5
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    • pp.405-410
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    • 2017
  • This paper deals with 3D simulation of industrial robot for automated manufacturing system. In order to evaluate the operational characteristics of the industrial robot system in the worst case motion scenario, flexible - rigid multibody analysis was performed. Then, the rigid body dynamics analysis was performed and the results were compared with the flexible - rigid multibody analysis. Modal analysis was also performed to confirm the dynamic characteristics of the robot system. In the case of the flexible-rigid multibody simulation, only the structural members of interest were modeled as elastic bodies to confirm the stress state. The remaining structural members were modeled as rigid bodies to reduce computer resources.

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.

Multibody Dynamics in Arterial System

  • Shin Sang-Hoon;Park Young-Bae;Rhim Hye-Whon;Yoo Wan-Suk;Park Young-Jae;Park Dae-Hun
    • Journal of Mechanical Science and Technology
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    • v.19 no.spc1
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    • pp.343-349
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    • 2005
  • There are many things in common between hemodynamics in arterial systems and multibody dynamics in mechanical systems. Hemodynamics is concerned with the forces generated by the heart and the resulting motion of blood through the multi-branched vascular system. The conventional hemodynamics model has been intended to show the general behavior of the body arterial system with the frequency domain based linear model. The need for detailed models to analyze the local part like coronary arterial tree and cerebral arterial tree has been required recently. Non-linear analysis techniques are well-developed in multibody dynamics. In this paper, the studies of hemodynamics are summarized from the view of multibody dynamics. Computational algorithms of arterial tree analysis is derived, and proved by experiments on animals. The flow and pressure of each branch are calculated from the measured flow data at the ascending aorta. The simulated results of the carotid artery and the iliac artery show in good accordance with the measured results.

A Real-time Multibody Vehicle Dynamics and Control Model for a Virtual Reality Intelligent Vehicle Simulator (가상현실 지능형 차량 시뮬레이터를 위한 실시간 다물체 차량 동역학 및 제어모델)

  • 김성수;손병석;송금정;정상윤
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.4
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    • pp.173-179
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    • 2003
  • In this paper, a real-time multibody vehicle dynamics and control model has been developed for a virtual reality intelligent vehicle simulator. The simulator consists of low PCs for a virtual reality visualization system, vehicle dynamics and control analysis system a control loading system, and a network monitoring system. Virtual environment is created by 3D Studio Max graphic tool and OpenGVS real-time rendering library. A real-time vehicle dynamics and control model consists of a control module based on the sliding mode control for adaptive cruise control and a real-time multibody vehicle dynamics module based on the subsystem synthesis method. To verify the real-time capability of the model, cut-in, cut-out simulations have been carried out.

Study on Parallel Processing for Efficient Flexible Multibody Analysis based on Subsystem Synthesis Method (병렬 처리를 이용한 부분 시스템 기반 유연다물체 동역학의 효율적인 해석 연구)

  • Han, Jong-Boo;Song, Hajun;Kim, Sung-Soo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.6
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    • pp.507-515
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    • 2017
  • Flexible multibody simulations are widely used in the industry to design mechanical systems. In flexible multibody dynamics, deformation coordinates are described either relatively in the body reference frame that is floating in the space or in the inertial reference frame. Moreover, these deformation coordinates are generated based on the discretization of the body according to the finite element approach. Therefore, the formulation of the flexible multibody system always deals with a huge number of degrees of freedom and the numerical solution methods require a substantial amount of computational time. Parallel computational methods are a solution for efficient computation. However, most of the parallel computational methods are focused on the efficient solution of large-sized linear equations. For multibody analysis, we need to develop an efficient formulation that could be suitable for parallel computation. In this paper, we developed a subsystem synthesis method for a flexible multibody system and proposed efficient parallel computational schemes based on the OpenMP API in order to achieve efficient computation. Simulations of a rotating blade system, which consists of three identical blades, were carried out with two different parallel computational schemes. Actual CPU times were measured to investigate the efficiency of the proposed parallel schemes.

Study on the Dynamic Model and Simulation of a Flexible Mechanical Arm Considering its Random Parameters

  • He Bai-Yan;Wang Shu-Xin
    • Journal of Mechanical Science and Technology
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    • v.19 no.spc1
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    • pp.265-271
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    • 2005
  • Randomness exists in engineering. Tolerance, assemble-error, environment temperature and wear make the parameters of a mechanical system uncertain. So the behavior or response of the mechanical system is uncertain. In this paper, the uncertain parameters are treated as random variables. So if the probability distribution of a random parameter is known, the simulation of mechanical multibody dynamics can be made by Monte-Carlo method. Thus multibody dynamics simulation results can be obtained in statistics. A new concept called functional reliability is put forward in this paper, which can be defined as the probability of the dynamic parameters(such as position, orientation, velocity, acceleration etc.) of the key parts of a mechanical multibody system belong to their tolerance values. A flexible mechanical arm with random parameters is studied in this paper. The length, width, thickness and density of the flexible arm are treated as random variables and Gaussian distribution is used with given mean and variance. Computer code is developed based on the dynamic model and Monte-Carlo method to simulate the dynamic behavior of the flexible arm. At the same time the end effector's locating reliability is calculated with circular tolerance area. The theory and method presented in this paper are applicable on the dynamics modeling of general multibody systems.

Study on Multibody Dynamic Analysis and Durability of Heavy Load Bucket Roller Chain System (고하중용 버킷 롤러체인 시스템의 다물체 동역학 해석 및 내구성 연구)

  • Kim, Chang Uk;Park, Jin Chul;Lee, Dong Woo;Song, Jung Il
    • Journal of the Korean Society for Precision Engineering
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    • v.33 no.11
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    • pp.919-925
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    • 2016
  • In this study, multibody dynamic and mechanical analyses were conducted for the structure of roller chain bucket elevator system. The fatigue life of the roller chain elevator system was determined under static and fatigue loadings. Results of multibody dynamic analysis suggested that the maximum contact force occurred at the drive sprocket engagement point with the roller chain due to maximum tension. Fatigue analysis results suggest that the high load roller chain system is durable and safe because its life time is more than 700,000 cycles, close to its designed value (1,000,000 cycle). However, the contact portion of plate and pin needed a safety factor. The dynamic analysis of the heavy load roller chain was conducted with a multibody dynamic analysis program. The results obtained in this study can be utilized for dynamic analysis of roller chain systems in all industries.

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.

Steady-State Equilibrium Analysis of a Multibody System Driven by Constant Generalized Speeds

  • Park, Dong-Hwan;Park, Jung-Hun;Yoo, Hong-Hee
    • Journal of Mechanical Science and Technology
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    • v.16 no.10
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    • pp.1239-1245
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    • 2002
  • A formulation which seeks steady-state equilibrium positions of constrained multibody systems driven by constant generalized speeds is presented in this paper. Since the relative coordinates are employed, constraint equations at cut joints are incorporated into the formulation. To obtain the steady-state equilibrium position of a multibody system, nonlinear equations are derived and solved iteratively. The nonlinear equations consist of the force equilibrium equations and the kinematic constraint equations. To verify the effectiveness of the proposed formulation, two numerical examples are solved and the results are compared with those of a commercial program.

Dynamic Analysis of the Latch Needle of the Circular Knitting Machine (환편기 편직바늘의 동역학해석)

  • Jeong, K.Y.
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.584-589
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    • 2001
  • The latch needle cam system of circular knitting machines is analysed using multibody dynamics. A formulation is made to obtain the vertical stiffness between the needle and the cam. By implementing this formulation into data of the multibody dynamics program, the motion and the force between the needle and the cam are obtained.

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