• Title/Summary/Keyword: Boundary Integral Equation

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Exact integration for the hypersingular boundary integral equation of two-dimensional elastostatics

  • Zhang, Xiaosong;Zhang, Xiaoxian
    • Structural Engineering and Mechanics
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    • v.30 no.3
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    • pp.279-296
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    • 2008
  • This paper presents an exact integration for the hypersingular boundary integral equation of two-dimensional elastostatics. The boundary is discretized by straight segments and the physical variables are approximated by discontinuous quadratic elements. The integral for the hypersingular boundary integral equation analysis is given in a closed form. It is proven that using the exact integration for discontinuous boundary element, the singular integral in the Cauchy Principal Value and the hypersingular integral in the Hadamard Finite Part can be obtained straightforward without special treatment. Two numerical examples are implemented to verify the correctness of the derived exact integration.

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.

Development and Application of Two-Dimensional Numerical Tank using Desingularized Indirect Boundary Integral Equation Method (비특이화 간접경계적분방정식방법을 이용한 2차원 수치수조 개발 및 적용)

  • Oh, Seunghoon;Cho, Seok-kyu;Jung, Dongho;Sung, Hong Gun
    • Journal of Ocean Engineering and Technology
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    • v.32 no.6
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    • pp.447-457
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    • 2018
  • In this study, a two-dimensional fully nonlinear transient wave numerical tank was developed using a desingularized indirect boundary integral equation method. The desingularized indirect boundary integral equation method is simpler and faster than the conventional boundary element method because special treatment is not required to compute the boundary integral. Numerical simulations were carried out in the time domain using the fourth order Runge-Kutta method. A mixed Eulerian-Lagrangian approach was adapted to reconstruct the free surface at each time step. A numerical damping zone was used to minimize the reflective wave in the downstream region. The interpolating method of a Gaussian radial basis function-type artificial neural network was used to calculate the gradient of the free surface elevation without element connectivity. The desingularized indirect boundary integral equation using an isolated point source and radial basis function has no need for information about the element connectivity and is a meshless method that is numerically more flexible. In order to validate the accuracy of the numerical wave tank based on the desingularized indirect boundary integral equation method and meshless technique, several numerical simulations were carried out. First, a comparison with numerical results according to the type of desingularized source was carried out and confirmed that continuous line sources can be replaced by simply isolated sources. In addition, a propagation simulation of a $2^{nd}$-order Stokes wave was carried out and compared with an analytical solution. Finally, simulations of propagating waves in shallow water and propagating waves over a submerged bar were also carried and compared with published data.

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.

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.

Solution for null field CVBIE in plane elasticity using an accurate shape function

  • Chen, Y.Z.
    • Advances in Computational Design
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    • v.6 no.2
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    • pp.77-98
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    • 2021
  • This paper provides a numerical solution for null field complex variable boundary integral equation (CVBIE) in plane elasticity. All kernels in the null field CVBIE are regular function. An accurate shape function for the displacement and traction along the contour is suggested. With the usage of suggested shape function, a discretization for the boundary integral equation (BIE) is carried out. The Dirichlet and the Neumann boundary value problems (BVPs) for the interior region and the exterior region are studied. Two numerical examples are provided in the paper. It is shown that a higher accuracy has been achieved in the examples with the usage of the suggested shape function.

An iteration approach for multiple notch problem based on complex variable boundary integral equation

  • Chen, Y.Z.
    • Structural Engineering and Mechanics
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    • v.41 no.5
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    • pp.591-604
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    • 2012
  • This paper provides an iteration approach for the solution of multiple notch problem, which is based on the complex variable boundary integral equation (CVBIE). The contours of notches are applied by some loadings. The source points are assumed on the boundary of individual notch and the displacements along the boundaries become unknowns to be investigated. After discretization of the BIE, many influence matrices are obtained. One does not need to assemble many influence matrices into a larger matrix. This will considerably reduce the work in the program. The displacements along the many boundaries can be obtained from an iteration. There is no limitation for the configuration of notches. Several numerical examples are provided to prove the efficiency of the suggested approach.

Properties of integral operators in complex variable boundary integral equation in plane elasticity

  • Chen, Y.Z.;Wang, Z.X.
    • Structural Engineering and Mechanics
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    • v.45 no.4
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    • pp.495-519
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    • 2013
  • This paper investigates properties of integral operators in complex variable boundary integral equation in plane elasticity, which is derived from the Somigliana identity in the complex variable form. The generalized Sokhotski-Plemelj's formulae are used to obtain the BIE in complex variable. The properties of some integral operators in the interior problem are studied in detail. The Neumann and Dirichlet problems are analyzed. The prior condition for solution is studied. The solvability of the formulated problems is addressed. Similar analysis is carried out for the exterior problem. It is found that the properties of some integral operators in the exterior boundary value problem (BVP) are quite different from their counterparts in the interior BVP.

Elastic Analysis of Unbounded Solids Using a Mixed Numerical Method (혼합 수치해석 방법을 이용한 무한고체의 탄성해석)

  • Lee , Jung-Ki;Heo, Kang-Il
    • Proceedings of the KSME Conference
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    • pp.341-348
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    • 2001
  • A Mixed Volume and Boundary Integral Equation Method is applied for the effective analysis of plane elastostatic problems in unbounded solids containing general anisotropic inclusions and voids or isotropic inclusions. 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. This new method can also be applied to general two-dimensional elastodynamic and elastostatic problems with arbitrary shapes and number of anisotropic inclusions and voids or isotropic inclusions. Through the analysis of plane elastostatic problems in unbounded isotropic matrix with orthotropic inclusions and voids or isotropic inclusions, it will be established that this new method is very accurate and effective for solving plane elastic problems in unbounded solids containing general anisotropic inclusions and voids or isotropic inclusions.

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Electric Field Analysis Using Three Dimensional Boundary Integral Equation Method (3차원 경계적분방정식법을 이용한 정전장 해석)

  • Kim, Jae-Hong;Kim, Dong-Hun;Park, Il-Han
    • Proceedings of the KIEE Conference
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    • pp.828-830
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    • 2000
  • This paper describes BIEM(Boundary Integral Equation Method) for computation of three dimensional electric field distribution and numerical method that an equivalent charge density is unknown variable. After computing numerically the surface charge distribution. the distribution of both potential and electric field are obtained. Finally, this numerical method is applied to the concentric sphere and the coaxial cylindrical model and numerical result is compared to the analytic solution.

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