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Wan-Suk Yoo(유완석),Oleg Dmitrochenko,Dmitry Pogorelov 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
The current state of the absolute nodal coor-dinate formulation (ANCF) is reviewed for large-displacement and large-deformation problems in flexible multibody dynamics. This review covers most of the known implementations of different kinds of finite elements including thin and thick planar and spatial beams and plates. Physical experiments were carried out to verify simulation resulats that show the accuracy of the ANCF applied to real physical problems. And simulation results are compared with experiments having significant geometrical non-linearity. A beam, a plate, a rotating chain, and a rotating strip were compared as examples. Current and further development directions of the ANCF are also briefly outlined.
범프 통과시 발생하는 충격신호에 대한 주관평가와 객관평가의 상관성 연구
유완석(Wan-Suk Yoo),김민석(Min-Seok Kim),장한기(Han-Kee Jang),안세진(Se-Jin Ahn) 한국자동차공학회 2005 한국 자동차공학회논문집 Vol.13 No.2
In oder to generate various shock signals in a field study, a passenger car was driven at several speeds over road profiles that included a number of half sine shaped bumps of various heights. A triaxial SAE pad sensor was mounted on the front passenger seat to measure the acceleration signals which might produce subjective discomfort. The measured accelerations were correlated with the subjective assessments of 14 subjects. The magnitude of subjective discomfort was found to be proportional to the VDV and also the peak to peak of the frequency weighted acceleration signal.
Simulation of a Rotating Chain with an Absolute Nodal Coordinate Formulation
유완석(Wan-Suk Yoo),Oleg Dmitrochenko(Oleg Dmitrochenko),Dmitry Pogorelov(Dmitry Pogorelov) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
A physically simple but mathematically cumbrous problem of rotating heavy chain with one fixed top point is studied. Nonlinear equation of its two-dimensional shapes of relative equilibrium is obtained and solved numerically. A linear case of small displacements is analyzed in terms of Bessel functions. The qualitative and quantitative behavior of the problem is discussed with the help of bifurcation diagram. Dynamics of the two-dimensional model near the equilibrium positions is studied with the help of simulation using the absolute nodal coordinate formulation (ANCF). The equilibriums are found instable, and the reason of instability is explained using a variational principle.
유완석(Wan Suk Yoo),나상도(Sang Do Na),김광석(Kwang Suk Kim) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.9
실시간 차량동역학 해석을 위해서는 효율적인 차량 모델이 필요하게 된다. 효율성을 높이기 위해 집중질량모델로 가정하면 현가장치의 특성을 고려하기 어렵게 되며, 현가장치의 특성을 모두 고려한 다물체동역학 모델에서는 효율성이 떨어진다. 그러므로 본 논문에서는 다물체동역학 모델링을 사용하되 해석의 효율성을 저하시키는 현가장치의 각종 요소들의 효과는 기구정역학 실험으로 추출된 특성그래프로 대체함으로써 효율성도 기하고자 시도하였다. 6x6 차량을 차체와 휠로 구성된 차량으로 모델을 정의 하였고, 다물체동역학 모델인 ADAMS 결과와 비교하여 실험적 모델의 유용성을 검증하였다. 그리고 검증된 실험적 차량모델을 RT-LAB 을 활용한 실시간 시뮬레이션 환경에 삽입하여, 실시간성 시뮬레이션의 가능성을 검증하였다. The paper presents an Experimental Vehicle Model (EVM), that utilizes the kinematic characteristics of suspensions from SPMD test data. The relative displacement and orientation of a wheel with respect to the body are represented as a function of the vertical displacement of the wheel. The equations of motion of the vehicle are formulated in terms of local coordinates that do not require coordinate transformation, which improves the efficiency of dynamic analysis. The EOM was modularized for each suspension model, and a 6 × 6 vehicle model was obtained by combining six suspensions. The analysis results were compared with ADAMS to verify the accuracy of the EVM. This study also verifies the feasibility of real-time simulation with the developed EVM. For a vehicle simulation for 1 ms, the real simulation time required within 20% of the prescribed time. This result shows that the EVM meets the real-time simulation requirements.
유완석(Wan-Suk Yoo) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
The development and the current state of the multibody dynamics is reviewed. Multibody dynmaics for a system of rigid bodies had been developed in 1970s. Flexible multibody dynamics with modal coordinates was introduced in 1980s to represent small deformation. And the absolute nodal coordinate formulation (ANCF) is proposed for large-displacement and large-deformation problems in late 1990s. This review covers history of the multibody dynamics for rigid body systems, flexible multibody dynamics for small deformations, and ANCF for large deformation problems. Several examples were also illustrated to explain the application fields of multibody dynamics.
유완석(Wan Suk Yoo),김태윤(Tae Yun Kim),정사무엘(Samuel Jung) 대한기계학회 2019 大韓機械學會論文集A Vol.43 No.7
17세기 뉴턴과 오일러에 의해 질점과 강체에 대한 운동방정식이 제안된 당시에는 3차원 운동방정식의 풀이가 쉽지 않아 실제적인 응용에는 한계가 있었다. 1970년대 들어와 컴퓨터가 공학에 응용되기 시작하여 동역학은 하나가 아닌 여러 개의 강체가 이루어진 시스템의 동역학인 다물체동역학으로 발전되기 시작했다. 본 연구에서는 지난 50년간의 다물체동역학의 발전 역사를 정리하면서, 앞으로의 발전방향에 대해서도 고찰하였다. The equations of motion of a rigid body were derived in the 17<SUP>th</SUP> century by Euler. The application was, however, confined to a simple problem due to the complexity of the equations of motion. Just after a computer was adopted for the engineering fields, application of dynamics was widened from one rigid body to a system of rigid bodies, i.e., multibody dynamics. In this paper, the history of multibody dynamics was reviewed, and the future of it is also carefully overviewed.