• Title, Summary, Keyword: 구조동역학

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An Automatic Time Stepping Algorithm Using a Prior Error Estimator in Structural Dynamics (구조동역학 문제에서 전단계 오차추정치를 이용한 자동시간간격 조정 알고리듬)

  • 조은형;정진태
    • Journal of KSNVE
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    • v.9 no.6
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    • pp.1240-1246
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    • 1999
  • A prior error estimator which is solving structural dynamic problems and which is based on the generalized-method, is developed. Since the proposed error estimator is computed with only previous information, the time step size can be adaptively selected without the feedback mechanism. This paper shows that the automatic time stepping algorithm using the error estimator performs an efficient time integration. To verify its efficiency, several examples are numerically investigated.

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Structural Analysis of Floating Offshore Wind Turbine Tower Based on Flexible Multibody Dynamics (탄성 다물체계 동역학을 기반으로 한 부유식 해상 풍력 발전기 타워의 구조 해석)

  • Park, Kwang-Phil;Cha, Ju-Hwan;Ku, Namkug;Jo, A-Ra;Lee, Kyu-Yeul
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.36 no.12
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    • pp.1489-1495
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    • 2012
  • In this study, we perform the structural analysis of a floating offshore wind turbine tower by considering the dynamic response of the floating platform. A multibody system consisting of three blades, a hub, a nacelle, the platform, and the tower is used to model the floating wind turbine. The blades and the tower are modeled as flexible bodies using three-dimensional beam elements. The aerodynamic force on the blades is calculated by the Blade Element Momentum (BEM) theory with hub rotation. The hydrostatic, hydrodynamic, and mooring forces are considered for the platform. The structural dynamic responses of the tower are simulated by numerically solving the equations of motion. From the simulation results, the time history of the internal forces at the nodes, such as the bending moment and stress, are obtained. In conclusion, the internal forces are compared with those obtained from static analysis to assess the effects of wave loads on the structural stability of the tower.

Investigation of Temperature-Dependent Microscopic Morphological Variation of PEEK Powder for a 3D Printer using Dissipative Particle and Molecular Dynamics Simulations (소산입자동역학과 분자동역학을 이용한 3D 프린터용 PEEK 분말에 대한 온도에 따른 미시적 구조변화에 대한 연구)

  • Kim, Namwon;Yi, Taeil
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.17 no.5
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    • pp.117-122
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    • 2018
  • 3D printing technology and its applications have grown rapidly in academia and industry. We consider a 3D printing system designed for the selective laser sintering (SLS) method, which is one of the powder bed fusion (PBF) techniques to build up the final product by layering sintered powder slices. Thermal distortion of printing products is a critical challenge in 3D printing. This study investigates temperature-dependent conformational behaviors of 3D printed samples of sintered poly-ether-ether-ketone (PEEK) powders using molecular dynamics simulations. The wear and chemical resistance properties of PEEK are understood, as it is a well-known biocompatible material used for implants. However, studies on physical phenomena at nanoscale in PEEK are rarely published in public. We simulate dissipative particle dynamics to elucidate how a cavity regime forms in PEEK at different system temperatures. We demonstrate how PEEK structures deform subject to the system temperature distribution.

Performance Evaluation of A Molecular Dynamics Code on Multi-core Systems (멀티 코어 시스템에서의 분자 동역학 코드 성능 분석)

  • Cha, Kwangho
    • Proceedings of the Korea Information Processing Society Conference
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    • pp.111-113
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    • 2013
  • 멀티 코어 시스템의 보급으로 일반 시스템에서도 프로그램의 병렬 실행이 가능해지고 있다. 본 연구에서는 멀티 코어를 사용하는 단일 시스템에서 분자 동역학 코드인 LAMMPS를 대상으로 병렬 수행 성능을 확인하고 분석하여 효과적인 실행 조건을 살펴보았다. LAMMPS의 구조적인 특징과 공간 분할 방식의 사용으로 인하여 단일 시스템에서도 메시지 전달 방식에 의한 병렬 수행이 보다 효율적임을 확인할 수 있었다.

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The molecular dynamics study of TBAB hydrogen hydrate structure (TBAB를 첨가한 수소 하이드레이트의 분자 동역학 연구)

  • Choi, Seungho;Park, Chansu;Kim, Soomin;Woo, Sungmin;Shin, Jaeho;Kim, Yangdo
    • 한국신재생에너지학회:학술대회논문집
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    • pp.153.1-153.1
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    • 2010
  • 가스 하이드레이트는 낮은 온도와 높은 압력에서 물과 천연가스 분자가 물리적으로 안정한 결합을 하고 있는 결정질의 화합물이다. 현재 130개 이상의 가스분자들이 물분자와 결합하여서 Clathrate 하이드레이트를 형성하는 것으로 보고 되어 있다. 수소의 경우 하이드레이트를 형성하기 위해서 약 200MPa 이상의 높은 압력이 필요하다. TBAB는 semi-clathrate 하이드레이트를 형성하는 첨가제로 알려져 있으며 수소 하이드레이트의 형성 압력을 완화시키기 위한 촉진제로서 많은 연구가 수행되고 있다. Wataru Shimada는 XRD 패턴을 사용하여 semi-clathrate 하이드레이트의 특수한 결정 모델을 분석하였다. 이 모델의 경우, 대기압 하에서 TBAB와 물분자의 화학 양론적 비를 1:38로 제시하였다. 이는 처음으로 TBAB 하이드레이트 결정구조를 밝혀냈지만, 분자 동역학적 부문에서는 그 데이터가 정확히 정의 되지 않았다. 본 연구는 Wataru Shimada 모델을 수소 TBAB 하이드레이이트의 분자 동역학 연구에 적용시켰으며, 실험에서 나온 데이터를 바탕으로 RDF(Radial Distribution Function)와 MSD(Mean Square Displacement)를 측정했다.

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Rigid Body Dynamic Analysis on the Spent Nuclear Fuel Disposal Canister under Accidental Drop and Impact to the Ground: Numerical analysis (사고로 지면으로 추락낙하 충돌하는 고준위폐기물 처분용기에 대한 기구동역학 해석: 수치해석)

  • Kwon, Young-Joo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.26 no.5
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    • pp.373-384
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    • 2013
  • This paper is the second paper among two papers which constitute the paper about the rigid body dynamic analysis on the spent nuclear fuel disposal canister under accidental drop and impact to the ground. This paper performed the numerical study on the rigid body dynamic analysis. Through this study the impulsive force which is occurring in the spent nuclear fuel disposal canister under accidental drop and impact to the ground and required for the structural safety design of the canister is computed numerically. The main content of this numerical study is about the technical method how to compute the impulsive forces occurring in the canister under accidental drop and impact to the ground by using the commercial rigid body dynamic analysis computer codes. On the basis of this study the impulsive force which is occurring in the canister in the case of collision with the ground is numerically computed. This numerically computed impulsive force is increasing as the canister weight is increasing, and the canister falls plumb down and collides with the ground in three types according to the analysis results.

분말소결 알루미늄 합금의 반복하중에 의한 미시균열 성장연구

  • ;;Klaus Detert
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.21-31
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    • 1991
  • 대부분의 구조물은 정하중뿐아니라 동하중을 받고있으며, 반복되는 동하중에 의해 구조물은 피로를 받게되고 가장 취약한 부위에 작은 미시균열이 발생된다. 미시균열이 성장, 확산되어 기술적으로 인지되는 길이가 0.5 mm 이상이 될때 이를 거시균열이라 하는데, 거시균열의 균열성장은 파괴역학적 해석 방법의 도입으로 많은 공학적 재료들이 광범위하게 연구되었으며, 거시균열의 확산과 연관되어지는 균열닫힘과 미시구조의 관계가 연구되었다. 최근에는 거시균열의 해석과 같이 응력강도가 미시균열에서의 확산거동에 미치는 영향을 설명하는데 많은 관심을 가지게 되었다.(중략)

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Evaluation of Crack-tip Cohesive Laws for the Mode I Fracture of the Graphene from Molecular Dynamics Simulations (그래핀의 모드 I 균열에 대한 분자동역학 해석으로부터 균열 선단 응집 법칙의 평가)

  • Kim, Hyun-Gyu
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.26 no.5
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    • pp.393-399
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    • 2013
  • In this paper, a novel approach to estimate cohesive laws for the mode I fracture of the graphene is presented by combining molecular dynamic simulations and an inverse algorithm based on field projection method and finite element method. The determination of crack-tip cohesive laws of the graphene based on continuum mechanics is a non-trivial inverse problem of finding unknown tractions and separations from atomic simulations. The displacements of molecular dynamic simulations in a region far away from the crack tip are transferred to finite element nodes by using moving least square approximation. Inverse analyses for extracting unknown cohesive tractions and separation behind the crack tip can be carried out by using conservation nature of the interaction J- and M-integrals with numerical auxiliary fields which are generated by systematically imposing uniform surface tractions element-by-element along the crack surfaces in finite element models. The preset method can be a very successful approach to extract crack-tip cohesive laws from molecular dynamic simulations as a scale bridging method.