• Title/Summary/Keyword: boundary integral method

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On the Vibration Analysis of the Floating Elastic Body Using the Boundary Integral Method in Combination with Finite Element Method

  • K.T.,Chung
    • Bulletin of the Society of Naval Architects of Korea
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    • v.24 no.4
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    • pp.19-36
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    • 1987
  • In this research the coupling problem between the elastic structure and the fluid, specially the hydroelastic harmonic vibration problem, is studied. In order to couple the domains, i.e., the structural domain and the fluid domain, the boundary integral method(direct boundary integral formulation) is used in the fluid domain in combination with the finite element method for the structure. The boundary integral method has been widely developed to apply it to the hydroelastic vibration problem. The hybrid boundary integral method using eigenfunctions on the radiation boundaries and the boundary integral method using the series form image-functions to replace the even bottom and free surface boundaries in case of high frequencies have been developed and tested. According to the boundary conditions and the frequency ranges the different boundary integral methods with the different idealizations of the fluid boundaries have been studied. Using the same interpolation functions for the pressure distribution and the displacement the two domains have been coupled and using Hamilton principle the solution of the hydroelastic have been obtained through the direct minimizing process. It has become evident that the finite-boundary element method combining with the eigenfunction or the image-function method give good results in comparison with the experimental ones and the other numerical results by the finite element method.

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THE INDIRECT BOUNDARY INTEGRAL METHOD FOR CURVED CRACKS IN PLANE ELASTICITY

  • Yun, Beong-In
    • Journal of the Korean Mathematical Society
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    • v.39 no.6
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    • pp.913-930
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    • 2002
  • For curved crack problems in plane elasticity, subjected to the traction conditions on the crack faces, we present a system of boundary integral equations. The procedure is based on the indirect boundary integral method in terms of real variables. For efficient mathematical analysis, we decompose the singular kernel into the Cauchy singular part and the regular one. As a result, solvability of the presented system is proved and availability of the present approach is shown by the numerical example of a circular arc crack.

A Composite Method of Finite Element and of Boundary Integral Methods for the Magnetic Field Problems with Open Boundary (유한요소법 및 경계적분법의 혼합법에 의한 개 영역 자장문제 해석)

  • 정현교;함송엽
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.36 no.6
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    • pp.396-402
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    • 1987
  • A Composite method of finite element and boundary integral methods is introduced to solve the magnetostatic field problems with open boundary. Only the region of prime interest is taken as the compution region where the finite element method is applied. The boundary conditions of the region are dealt with using boundary integral method. The boundary integration in the boundary integral method is done by numerical and analytical techniques repectively. The proposed method is applied to a simple linear problem, and the results are compared with those of the finite element method and the analytic solutions. It is concluded that the proposed method gives more accurate results than the finite element method under the same computing efforts.

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REMOVAL OF HYPERSINGULARITY IN A DIRECT BEM FORMULATION

  • Lee, BongJu
    • Korean Journal of Mathematics
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    • v.18 no.4
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    • pp.425-440
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    • 2010
  • Using Green's theorem, elliptic boundary value problems can be converted to boundary integral equations. A numerical methods for boundary integral equations are boundary elementary method(BEM). BEM has advantages over finite element method(FEM) whenever the fundamental solutions are known. Helmholtz type equations arise naturally in many physical applications. In a boundary integral formulation for the exterior Neumann there occurs a hypersingular operator which exhibits a strong singularity like $\frac{1}{|x-y|^3}$ and hence is not an integrable function. In this paper we are going to remove this hypersingularity by reducing the regularity of test functions.

A Study on Structural Analysis for Aircraft Gas Turbine Rotor Disks Using the Axisymmetric Boundary Integral Equation Method (축대칭 경계적분법에 의한 항공기 가스터빈 로터디스크 구조해석에 관한 연구)

  • Kong, Chang-Duk;Chung, Suk-Choo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.8
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    • pp.2524-2539
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    • 1996
  • A design process and an axisymmetric boundary integral equation method for precise structural analysis of the aircraft gas turbine rotor disk were developed. This axisymmetric boundary integral equation method for stress and steady-state thermal analysis was improved in solution accuracy by appling an implicit technique for Cauchy principal value evaluation, a subelement technique for weak singular integral evaluation and a double exponentical integral technoque for internal point solution near boundary surfaces. Stresses, temperatures, low cycle fatigue lifes and critical speeds for the turbine rotor disk of the thrust 1421 N class turbojet engine were analysed in a pratical calculation model problem.

A Composite of FEM and BIM Dealing with Neumann and Dirichlet Boundary Conditions for Open Boundary magnetic Field Problems (개량역 자장간의 해석에 있어서 Neumann 및 Diichlet 경계조건을 고려한 유한요소법 및 경계적분법)

  • 정현교;한송엽
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.36 no.11
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    • pp.777-782
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    • 1987
  • A new composite method of finite element and boundary integral methods is presented to solve the two dimensional magnetostatic field problems with open boundary. The method can deal with the current source of the boundary integral regin where the boundary integral method is applied, and also Neumann and Dirichlet boundary conditions at the interfacial boundary between the boundary integral region and the finite element region where the finite element method is applied. The new approach has been applied to a simple linear problem to verify the usefulness. It is shown that the proposed algorithm gives more accurate results than the finite element methed under the same elementdiscretization.

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A boundary-volume integral equation method for the analysis of wave scattering

  • Touhei, Terumi
    • Coupled systems mechanics
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    • v.1 no.2
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    • pp.183-204
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    • 2012
  • A method for the analysis of wave scattering in 3-D elastic full space is developed by means of the coupled boundary-volume integral equation, which takes into account the effects of both the boundary of inclusions and the uctuation of the wave field. The wavenumber domain formulation is used to construct the Krylov subspace by means of FFT. In order to achieve the wavenumber domain formulation, the boundary-volume integral equation is transformed into the volume integral equation. The formulation is also focused on this transform and its numerical implementation. Several numerical results clarify the accuracy and effectiveness of the present method for scattering analysis.

Elastic Analysis of a Half-Plane Containing an Inclusion and a Void Using Mixed Volume and Boundary Integral Equation Method (혼합 체적-경계 적분방정식법을 이용한, 함유체와 공동을 포함한 반무한 고체에서의 탄성해석)

  • Lee, Jung-Ki;Yoon, Koo-Young
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.12
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    • pp.1072-1087
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    • 2008
  • A mixed volume and boundary integral equation method (Mixed VIEM-BIEM) is used to calculate the plane elastostatic field in an isotropic elastic half-plane containing an isotropic or anisotropic inclusion and a void subject to remote loading parallel to the traction-free boundary. A detailed analysis of stress field at the interface between the isotropic matrix and the isotropic or orthotropic inclusion is carried out for different values of the distance between the center of the inclusion and the traction-free surface boundary in an isotropic elastic half-plane containing three different geometries of an isotropic or orthotropic inclusion and a void. The method is shown to be very accurate and effective for investigating the local stresses in an isotropic elastic half-plane containing multiple isotropic or anisotropic inclusions and multiple voids.

Calculation of Stress Intensity Factors Using the Mixed Volume and Boundary Integral Equation Method (혼합 체적-경계 적분방정식법을 이용한 응력확대계수 계산)

  • Lee, Jung-Ki;Lee, Hyeong-Min
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.7
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    • pp.1120-1131
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    • 2003
  • A recently developed numerical method based on a mixed volume and boundary integral equation method is applied to calculate the accurate stress intensity factors at the crack tips in unbounded isotropic solids in the presence of multiple anisotropic inclusions and cracks subject to external loads. Firstly, it should be noted that this newly developed numerical method does not require the Green's function for anisotropic inclusions to solve this class of problems since only Green's function for the unbounded isotropic matrix is involved in their formulation for the analysis. Secondly, this method takes full advantage of the capabilities developed in FEM and BIEM. In this paper, a detailed analysis of the stress intensity factors are carried out for an unbounded isotropic matrix containing an orthotropic cylindrical inclusion and a crack. The accuracy and effectiveness of the new method are examined through comparison with results obtained from analytical method and volume integral equation method. It is demonstrated that this new method is very accurate and effective for solving plane elastostatic problems in unbounded solids containing anisotropic inclusions and cracks.

Application of the Boundary Element Method to Finite Deflection of Elastic Bending Plates

  • Kim, Chi Kyung
    • International Journal of Safety
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    • v.2 no.1
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    • pp.39-44
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    • 2003
  • The present study deals with an approximate integral equation approach to finite deflection of elastic plates with arbitrary plane form. An integral formulation leads to a system of boundary integral equations involving values of deflection, slope, bending moment and transverse shear force along the edge. The basic principles of the development of boundary element technique are reviewed. A computer program for solving for stresses and deflections in a isotropic, homogeneous, linear and elastic bending plate is developed. The fundamental solution of deflection and moment is employed in this program. The deflections and moments are assumed constant within the quadrilateral element. Numerical solutions for sample problems, obtained by the direct boundary element method, are presented and results are compared with known solutions.