• 한국산업융합학회 논문집
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• 제20권5호
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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.

• Journal of Mechanical Science and Technology
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• 제18권7호
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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.

• Journal of Mechanical Science and Technology
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• 제19권spc1호
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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.

• 한국자동차공학회논문집
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• 제11권4호
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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.

• 대한기계학회논문집A
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• 제41권6호
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• pp.507-515
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• 2017

많은 절점 자유도로 표현이 되는 유연다물체 시스템의 효율적인 해석을 위해서는 병렬처리 기법이 적용될 수 있다. 이 분야에서의 병렬처리기법은 주로 선형대수방정식의 효율적인 해법에 초점이 맞추어 연구가 진행되었다. 본 논문에서는 기존의 방법과는 달리 병렬처리에 적합한 유연다물체 동역학 공식을 부분 시스템 합성방법을 이용하여 개발하고, OpenMP를 사용한 효율적인 병렬처리 방식을 제안하였다. 서로 다른 두 가지 병렬처리 방식을 3개의 동일한 유연체 회전 날개 시스템 시뮬레이션 통하여 비교하였다. 또한 실제의 CPU시간을 비교하여 제안한 병렬처리 방법의 효율성을 고찰하였다.

• Journal of Mechanical Science and Technology
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• 제19권spc1호
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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.

• 한국정밀공학회지
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• 제33권11호
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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.

• 대한기계학회논문집A
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• 제21권8호
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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.

• Journal of Mechanical Science and Technology
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• 제16권10호
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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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.