• Korea-Australia Rheology Journal
• /
• 제21권1호
• /
• pp.39-46
• /
• 2009

Atherosclerosis is a disease that narrows, thickens, hardens, and restructures a blood vessel due to substantial plaque deposit. The geometric models of the considered stenotic blood flow are three different types of constriction of cross-sectional area of blood vessel; 25%, 50%, and 75% of constriction. The computational model with the fluid-structure interaction is introduced to investigate the wall shear stresses, blood flow field and recirculation zone in the stenotic vessels. The velocity profile in a compliant stenotic artery with various constrictions is subjected to prescribed physiologic waveform. The computational simulations were performed, in which the physiological flow through a compliant axisymmetric stenotic blood vessel was solved using commercial software ADINA 8.4 developed by finite element method. We demonstrated comparisons of the wall shear stress with or without the fluid-structure interaction and their velocity profiles under the physiological flow condition in the compliant stenotic artery. The present results enhance our understanding of the hemodynamic characteristics in a compliant stenotic artery.

• Nuclear Engineering and Technology
• /
• 제55권12호
• /
• pp.4307-4316
• /
• 2023

In this paper, modal effective mass for asymmetric fluid-structure interaction system is defined and equations for its calculation is derived. To establish consistency, modal effective mass in symmetric structure only system is briefly reviewed, followed by a definition of the modal effective mass in asymmetric system. The equations for calculating modal effective mass in asymmetric system are derived by utilizing the properties of left and right eigenvectors. To simplify the equations, the assumption is made that the mass matrix is only affected by the fluid. The simplified equation is then compared to the equation already used in ANSYS. Finally, the validity of the modal effective mass definition and derivation in this paper is demonstrated through a simple example.

• 한국소음진동공학회논문집
• /
• 제21권5호
• /
• pp.422-429
• /
• 2011

The critical fluid velocity of cantilevered cylindrical shells subjected to internal fluid flow is investigated in this study. The fluid-structure interaction is considered in the analysis. The cantilevered cylindrical shell is supported intermediately at an arbitrary axial position. The intermediate support is simulated by two types of artificial springs: translational and rotational spring. It is assumed that the artificial springs are placed continuously and uniformly on the middle surface of an intermediate support along the circumferential direction. The steady flow of fluid is described by the classical potential flow theory. The motion of shell is represented by the first order shear deformation theory (FSDT) to account for rotary inertia and transverse shear strains. The effect of internal fluid can be considered by imposing a relation between the fluid pressure and the radial displacement of the structure at the interface. Numerical examples are presented and compared with existing results.

• 한국시뮬레이션학회논문지
• /
• 제25권1호
• /
• pp.1-9
• /
• 2016

본 연구는 공대공 미사일 조종날개의 공력 및 구조를 동시에 고려한 구동력 최소화에 대한 최적화를 수행하였다. 본 연구에서는 조종날개의 공력 및 구조적 특성을 동시에 고려하기 위하여 공력-구조 연계 시뮬레이션을 사용하였으며 공력 및 구조 시뮬레이션에 각각의 전용 소프트웨어를 사용하고자 비정상-약결합 방식 연계기법을 적용하였다. 전역 최적화에는 많은 반복 계산이 필요하므로 빠른 계산을 위하여 수학적 모델링을 이용하였으며 이를 위하여 면 중앙 합성 실험계획법으로 실험점을 선정하였다. 선정된 실험점 및 그에 대한 공력-구조 연계 시뮬레이션 결과를 토대로 2차 다항식 반응면을 생성하였으며 생성된 수학적 모델링을 이용, 유전자 알고리즘 기반 전역최적 설계를 수행하였다. 최적화 목적함수는 마하 0.7 및 마하 2.0 사이의 압력 중심점 이동거리 최소화로 설정하였으며 최적화 결과 압력 중심점 이동거리가 7.5% 감소된 최적형상을 도출하였다.

• Interaction and multiscale mechanics
• /
• 제6권4호
• /
• pp.357-375
• /
• 2013

In this paper, the forced vibration problem of an Euler-Bernoulli beam that is joined with a semi-infinite field of a compressible fluid is considered as a boundary value problem (BVP). This BVP includes two partial differential equations (PDE) and some boundary conditions (BC), which are introduced comprehensively. After that, the closed-form solution of this fluid-structure interaction problem is obtained in the frequency domain. Some mathematical techniques are utilized, and two unknown functions of the BVP, including the beam displacement at each section and the fluid dynamic pressure at all points, are attained. These functions are expressed as an infinite series and evaluated quantitatively for a real example in the results section. In addition, finite element analysis is carried out for comparison.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.419-424
• /
• 2004

we performed the underwater explosion analysis for the liquefied oxygen tank - a kind of fuel tank of a mid-size submarine, and tried to verify the structural safety for this structure. First, we reviewed the theory and application of underwater explosion analysis using Structure-Fluid Interaction technique and its finite element modeling scheme. Next, we modeled the explosive and sea water as fluid elements, the LOX tank as structural elements and the interface between two regions as ALE scheme. The effect on shock pressure and impulse of fluid mesh size and shape are also investigated. As the analysis result, the shock pressure due explosion propagated into the water region and hit the structure region. The plastic deformation and the equivalent stress highly appeared at the web frame and the shock mount of LOX structure, but these values were acceptable for design criteria.

• 한국해양공학회지
• /
• 제19권1호
• /
• pp.20-25
• /
• 2005

The authors performed the underwater explosion analysis for the liquified oxygen tank - a kind of fuel tank of a mid-size submarine, and tried to verify the structural safety for this structure. First, the authors reviewed the theory and application of underwater explosion analysis, using a Structure-Fluid Interaction technique and its finite element modeling scheme. Next, the authors modeled the explosive and sea water as fluid elements, the LOX tank as structural elements, and the interface between the two regions as the ALE scheme. The effect on shock pressure and impulse of fluid mesh size and shape are also investigated. Upon analysis, it was found that the shock pressure due to explosion propagated into the water region, and hit the structure region. The plastic deformation and the equivalent stress were apparent at the web frame and the shock mount of LOX structure, but these values were acceptable for the design criteria.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2008년도 추계학술대회논문집
• /
• pp.121-122
• /
• 2008

In this paper, computational analysis on the steady-state and transient behaviors of the valve system is discussed. Fluid-structure interaction (FSI) is taken into account using ADINA software. The computational results are experimentally validated.

• International Journal of Ocean System Engineering
• /
• 제1권2호
• /
• pp.76-88
• /
• 2011

The present study deals with the hydroelastic vibration analysis of structures in contact with fluid via coupled fluid-structure interaction (FSI) embedded with a finite element method (FEM) such that a structure displacement formulation is coupled with a fluid pressure-displacement formulation. For the preliminary study and validation of FEM based coupled FSI analysis, hydroelastic vibration characteristics of a rectangular plate in contact with fluid are first compared with the elastic vibration in terms of boundary condition and mode frequency. Numerical results from coupled FSI analysis have been shown to be rational and accurate, compared to energy method based theoretical solutions and experimental results. The effect of free surface on the vibration mode is numerically studied by changing the submerged depth of a rectangular plate. As a practical application, the hull structural vibration of 4,000 twenty-foot equivalent units (TEU) container ship is considered. Hydroelastic results of the ship hull structure are compared with those obtained from the elastic condition.

• 한국소음진동공학회논문집
• /
• 제22권8호
• /
• pp.763-770
• /
• 2012

The free vibration characteristics of fluid-filled cylindrical shells on partial elastic foundations are investigated by an analytical method. The cylindrical shell is fully or partially surrounded by the elastic foundations, these are represented by the Winkler or Pasternak model. The motion of shell is represented by the first order shear deformation theory to account for rotary inertia and transverse shear strains. The steady flow of fluid is described by the classical potential flow theory. The fluid-structure interaction is considered in the analysis. The effect of internal fluid can be considered by imposing a relation between the fluid pressure and the radial displacement of the structure at the interface. To validate the present method, the numerical example is presented and compared with the available existing results.