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탄성기계 시스템의 동적 거동 해석을 위한 수치 적분 알고리즘 개선에 관한 연구
김외조(Oe-Jo Kim),김현철(Hyun-chul Kim) 한국산업융합학회 2001 한국산업융합학회 논문집 Vol.4 No.1
In multibody dynamics, differential and algebraic equations which can satisfy both equation of motion and kinematic constraint equation should be solved. To solve this equation, coordinate partitioning method and constraint stabilization method are commonly used. The coordinate partitioning method divides the coordinate into independent and dependent coordinates. The most typical coordinate partitioning method arc LU decomposition, QR decomposition, projection method and SVD(sigular value decomposition).The objective of this research is to find a efficient coordinate partitioning method in flexible multibody systems and a hybrid decomposition algorithm which employs both LU and projection methods is proposed. The accuracy of the solution algorithm is checked with a slider-crank mechanism.<br/> <br/>
탄성 시스템에서의 효율적인 좌표분할법 선정에 관한 연구
김외조,유완석,Kim, Oe-Jo,Yoo, Wan-Suk 대한기계학회 1997 大韓機械學會論文集A Vol.21 No.8
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.
준역행렬과 투영행렬을 이용한 구속 다물체계의 동역학 해석
김외조,유완석,Kim, Oe-Jo,Yoo, Wan-Suk 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.1
In this paper, the column space and null space of the Jacobian matrix were obtained by using the pseudo-inverse method and projection matrix. The equations of motion of the system were replaced by independent acceleration components using the null space matrix. The proposed method has the following advantages. (1) It is simple to derive the null space. (2) The efficiency is improved by getting rid of constrained force terms. (3) Neither null space updating nor coordinate partitioning method is required. The suggested algorithm is applied to a three-dimensional vehicle model to show the efficiency.
김외조,유완석,윤경화,강하근,Kim, Oe-Jo,Yu, Wan-Seok,Yun, Kyeong-Hwa,Gang, Ha-Geun 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.4
This paper presents a three dimensional modeling and dynamic anlaysis of a hydraulic excavator. An excavator is composed of a ground, an under-frame, two idlers, two spockets, an upper-frame, a boom, an arm, a bucket two yokes, two connecting rods, two boom cylinders, an arm cylinder, and a bucket cylinder. Each cylinder is modeled with two separate bodies which are linked to each other by a translational joint. The three dimensioanl model of the excavator consists of 22 bodies and each body is assumed as rigid. This paper suggested the maximum lifting capability, a critical load and reaction forces at joints form the DADS simulation. It was presumed that the reaction forces due to a critical load are three times bigger than those due to the maximum lifting capacity.
폐쇄연쇄계를 갖는 탄성 다물체계의 효율적인 조인트반력 해석
최용철,김광석,김외조,유완석,Choi, Yong-Cheol,Kim, Gwang-Seok,Kim, Oe-Jo,Yoo, Wan-Seok 대한기계학회 1998 大韓機械學會論文集A Vol.22 No.3
The analysis of dynamic forces is essential to the design of systems, stress analysis, or life prediction of part of machine. Calculation of dynamic forces has very close relations with multibody dynamics algorithm. In this paper, an algorithm which calculates joint reaction force/moment of flexible multibody dynamic systems is proposed by using inverse dynamic algorithm and velocity transformation technique.
김광석(Kwang-Suk Kim),김외조(Oe-Jo Kim),최태용(Tae-Yong Choi),황석환(Suk-Hwang Hwang),강동권(Dong-Kwong Kang),유완석(Wan-Suk Yoo),김성수(Sung-Soo Kim) 한국자동차공학회 1995 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1995 No.11_1
In this study, a vehicle dynamic analysis program AUTODYN7(AUTOmobil DYNamics in G7) is developed and introduced. An efficient and systematic formulation for dynamics of spatial multibody systems with flexible bodies is presented using the Velocity Transformation technique. In order to reduce the number of elastic coordinates. elastic deformations are represented by the vibration normal modes obtained from finite element analysis. A pre-processor which transforms input data from ADAMS or DADS to AUTODYN7 is also developed.<br/>