• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2011.11a
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• pp.37-39
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• 2011

예선이 부선을 예인줄로 연결하여 운항할 시 예인줄에 걸리는 장력 및 형상을 예인줄을 다물체로 분할하여 모델링하였다. 이러한 예인줄 요소에 대한 횡동요를 제외한 5자유도 운동방정식을 구성하고, 각 요소들에 작용하는 힘을 정식화하여 연성 운동방정식을 도출하였다. 예인줄 요소들 간에는 예인줄의 재료 특성에 따른 강성을 가진 스프링과 감쇠장치로 연결하여 동력학적 조건을 부가하였고, 요소의 변형을 허용하는 형태로 운동학적 조건은 설정하지 않았다. 예인줄의 다물체 모델링의 검증을 위하여 단순 낙하, 직진, 사인파 형태로 지그재그로 움직이는 예선과 단순 항력체로 가정한 부선의 운동에 대한 시뮬레이션을 수행하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.115-120
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• 2014

In this study, a module is developed for modeling and analyzing dynamic behavior of a wind turbine using RecurDyn, which is a commercial multi-body dynamics software developed by FunctionBay, Inc. The wind turbine consists of tower, nacelle, hub and blades. Tower and blades are regarded as flexible bodies for considering elastic effect using beam theory and spring force. In this paper, a constant speed wind was assumed and aerodynamic force is modeled using BEM theory. Dynamic analysis applying this aerodynamic force is carried out. To verify the validity of analysis results, these results are compared to those of GH-Bladed which is a commercial software for analyzing wind turbine system distributed by Garrad Hassan.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.9
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• pp.775-780
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• 2016

In this paper, a computational algorithm of an improved and versatile structural analysis applicable for large-size flexible nonlinear structures is developed. In more detail, nonlinear finite element based on the co-rotational (CR) framework is developed. Then, a finite element tearing and interconnecting method using local Lagrange multipliers (FETI-local) is combined with the nonlinear CR finite element. The resulting computational algorithm is presented and applied for nonlinear static analyses, i.e., cantilevered beam and multibody structure. Finally, the proposed analysis is evaluated with regard to its parallel computation performance, and it is compared with those obtained by serial computation using the sparse matrix linear solver, PARDISO.

• Journal of Navigation and Port Research
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• v.36 no.5
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• pp.339-347
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• 2012

After towing rope connecting a barge to a tug was subdivided into multiple finite elements, then those dynamic models was established using Newton's second law and considering the external force and moment such as tension, drag, Coriolis force, gravity, buoyancy, and impact due to free surface acting on each element. While the previous research on the model of towing rope considered only translation, five-degree-of-freedom equations of motion except roll based on the body-fixed frame were established in this paper. All elements are connected by a spring and a damper, and the stiffness of the spring was set as the equivalent value of the real rope. In order to confirm the established multiple finite element model, various scenarios such as freely falling of towing rope in the air and above the free surface, accelerating of a tug which tows a barge connected by towing rope, and sinusoidal moving of a tug were set up and simulated. As the results, the trajectories of the tug, the barge, and the towing rope showed good tendencies to the ones of real expected situations.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.4
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• pp.239-247
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• 2013

Recently renewable energy such as offshore wind energy takes a higher interest due to the depletion of fossil fuel and the environmental pollution. This paper deals with multi-body dynamics (MBD) analysis technique for offshore wind turbine system considering aerodynamic loads and Thevenin equation used for determination of electric generator torque. Dynamic responses of 5MW offshore wind turbine system are evaluated via the MBD analysis, and the system is the horizontal axis wind turbine (HAWT) which generates electricity from the three blades horizontally installed at upwind direction. The aerodynamic loads acting on the blades are computed by AeroDyn code, which is capable of accommodating a generalized dynamic wake using blade element momentum (BEM) theory. In order that the characteristics of dynamic loads and torques on the main joint parts of offshore wind turbine system are simulated similarly such an actual system, flexible body modeling including the actual structural properties are applied for both blade and tower in the multi-body dynamics model.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.141-149
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• 2005

This paper deals with formulations of the energy equilibrium equation by an introduction of the algebraic description, quarternion, which meets conservations of system energy for the equation of motion. Then the equation is discretized to analyze the dynamits analysis of flexible multibody systems in such a way that the work done by the constrained force completely is eliminated. Meanwhile, Rodrigues parameters we used to express the finite rotation lot the proposed method. This method lot the initial essential step to a guarantee of developments of the 3D dynamical problem provides unconditionally stable conditions for the nonlinear problems through the numerical examples.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.167.1-167.1
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• 2012

본 논문에서는 인공위성 전개장치용 테잎힌지 특성해석을 수행하고 그 결과에 대하여 분석하였다. 테잎힌지를 이용한 전개장치는 신뢰성이 높고, 형상이 매우 단순하며, 제작단가 또한 저렴하여 우주용 안테나 및 태양전지판에 널리 이용이 되고 있다. 테잎힌지를 이용한 전개장치의 전개특성은 테잎힌지 특성에 의하여 좌우가 되므로 안전성 있는 전개장치 설계를 수행하기 위해서는 가능한 정확한 해석이나 계산이 요구되어진다. 초기에는 쉘 이론등을 바탕으로 테잎힌지의 전개특성을 계산하는 식들이 연구되었으나 테잎힌지의 강한 비선형성 때문에 정확성이 많이 떨어지는 큰 단점이 존재하였다. 이후 많은 연구를 통하여 유한요소모델을 이용한 비선형해석을 통하여 비로소 정확한 전개특성을 해석할 수 있게 되었다. 본 논문에서는 다물체 동역학해석프로그램인 리커다인의 유연체 해석모듈을 이용하여 테잎힌지에 대한 특성해석을 수행하였다. 해석결과 신뢰성 있는 테잎힌지의 전개거동 확인 및 전개특성을 계산할 수 있었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.575-584
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• 2014

In this study, the NREL 5 MW wind turbine tower model was optimized according to the multi-body dynamics and reliability-based design. The mathematical model was defined as a link-joint system including dynamic characteristics derived from Timoshenko's beam theory. For the optimization problem, the sensitivities to variations in the tower thicknesses and inner and outer diameters were acquired and arranged in terms of safety and efficiency according to bending stress and buckling standards. An optimal design was calculated with the advanced first-order second moment method and used to define a finite element model for validation. The finite element model was simulated by static analysis. The relationship between the multi-body dynamic and finite element method throughout the process was investigated, and the optimal model, which had high endurance despite its low mass, was determined.