• Title/Summary/Keyword: 경계적분방정식

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On Dual Boundary Integral Equations for Crack Problems (이중 경계적분방정식에 의한 크랙 문제의 해석)

  • ;T.J. Rudolphi
    • Journal of the Korean Society for Precision Engineering
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    • v.12 no.10
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    • pp.89-101
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    • 1995
  • 선형 탄성 등방성 물체 내에 있는 일반적인 복합모드 크랙 문제들을 해석하기 위한 이중 경계적분방정식의 일반식과 계산해법이 제시되었다. 크랙면이 포함된 물체 해석에 있어서 유일한 해를 얻기 위하여, 한 면상의 점에는 변위 경계적분방정식이 적용되었고 마주하고 있는 상대면 상의 점에는 인력 경계적분방정식이 적용되었다. 인력 및 변위 경계적분방정식의 강특이해 및 초특이해 적분항들은 수치해법을 적용하기 전에 정상화되었다. 정상화과정 중 보정되는 강특이적분항이 상대 크랙면 상의 특이해 요소를 따라 직접 적분되는 것을 격리시키기 위하여, 특이해 적분 경로를 완만한 곡면으로 우회시킨 가상의 비특이해 보조경계로 대치하여 적분값을 계산하였다. 제시된 해법의 정확성과 효율성을 예시하기 위하여, 2차원 및 3차원 크랙 문제의 변형 후 모습과 응력강도계수 계산 결과를 보였다.

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A Boundary Integral Approximation for Bending of Elastic Plates (탄성평판 굽힘문제를 위한 경계적분 근사해)

  • Kim, Jin Woo
    • Journal of the Korea Institute of Military Science and Technology
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    • v.5 no.4
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    • pp.57-66
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    • 2002
  • 본 연구는 굽힘 하중하에서 탄성평판 구조 해석을 위한 경계적분방법 구성을 주목적으로 하고 체계적인 모듈화시스템 개발의 첫 이론 부분을 확립하였다. 굽힘 문제에서의 4개의 고유변수인 처짐, 기울기, 굽힘모우멘트, 상당 전단력의 항으로 경계적분방정식을 구성하였다. 물리적인 의미를 갖는 두 새로운 핵함수 도입으로 구성된 이들 적분방정식은 경계요소 구성시 나타나는 특이거동의 문제점을 간단한 두 탄성해에 의해 정규화 시켰으며 수치 적분 과정도 Cauchy 주치 적분 수렴성에서의 특별취급과는 달리 효율적으로 일반화시켰다. 경계적분식의 수치해석방법을 서술하였으며 집중하중하의 비대칭문제의 근사수치해를 도시하였다.

Shape Design Sensitivity Analysis of Axisymmetric Thermal Conducting Solids Using Boundary Integral Equations (경계적분방정식을 이용한 축대칭 열전도 고체의 형상설계민감도 해석)

  • 이부윤
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.1
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    • pp.141-152
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    • 1993
  • A generalized method is presented for shape design sensitivity analysis of axisymmetric thermal conducting solids. The shape sensitivity formula of a general performance functional arising in shape optimal design problem is derived using the material derivative concept and the adjoint variable method. The method for deriving the formula is based on standard axisymmetric boundary integral equation formulation. It is then applied to obtain the sensitivity formulas for temperature and heat flux constraints imposed over a small segment of the boundary. To show the accuracy of the sensitivity analysis, numerical implementations are done for three examples. Sensitivities calculated by the presented method are compared with analytic sensitivities for two examples with analytic solutions, and compared with sensitivies by finite difference for a cooling fin example.

Progressive Fracture Analysis of Concrete by Boundary Element Method and its Stabilizing Technique (경계요소법에 의한 콘크리트의 파괴진행해석 및 안정화 기법)

  • 송하원;전재홍
    • Magazine of the Korea Concrete Institute
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    • v.8 no.6
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    • pp.205-212
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    • 1996
  • This paper presents progressive fracture analysis of concrete using boundary element method and its stabilizing technique. To determine ultimate strength and to predict nonlinear behavior of concrete during progressive crack growth, the modelling of fracture process zone is done based on Dugdale-Barenblatt model with linear tension-softening curve. We regulate displacement and traction boundary integral equation of solids including crack boundary and analyze progressive fracture of concrete beam and compact tension specimen. Also a numerical technique which considers the growth of stress-free crack of concrete during the analysis and removes snapback of postpeak behavior is proposed.

A Boundary Integral Formulation for Vibration Problems of Plate using Laplace Transform (Laplace변환을 이용한 판 진동문제의 경계적분방정식 정식화)

  • 이성민;서일교;권택진
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.9-16
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    • 1994
  • In this paper, a boundary integral equation for transient plate bending problem is proposed. Approach, using laplace transform is considered. The boundary integral equations with respect to deflection, normal slope, bending moment effective shear are presented and the effect of corner point is considered.

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탄성학 문제의 경계적분방정식에서 초특이해 커널의 해법

  • 윤승원
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.573-577
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    • 1995
  • An integration method for the hypersingular kernels, in the boundary integralequations used for the solution of crack-like problems in elasticity, has been developed. To isolate the stronger singularities, the actual boundaries are replaced by the smoothly curved auxiliary boundaries which provide the detoured, non-singular integration paths. The auxiliary boundary can be interpreted as a contracted form of the actual boundaries except for the singular element where the collocating point is located. For an optimal integration path for every singular collocation point, the auxiliary boundary may have different shape depending on the position of the collocation point on the singular element.

A Boundary Integral Approximation For the Stress Intensity Factors in Elastic Plate Bending (강성평판굽힘 문제의 응력확대계수를 위한 경계적분수치해법)

  • Kim, J. W.
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.6 no.3
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    • pp.282-288
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    • 1982
  • 크랙탄성평판의 굽힘문제가 경계적분방정식으로 구성되었다. 자연변수인 변위, 수직기울기, 굽힘 모우멘트, 등가전단적과 크랙끝에서 응력의 성장율로 정의되는 응력확대계수들이 주변수로 포함 된다. 이 적분방정식들은 가역에너지 적분이론(Green-Rayleigh)을 기초로 크랙응력분포특성에 맞 게 발전되었으며 해당되는 핵함수들이 유도되었다. 등분석 모우멘트를 받는 중앙크랙이 있는 정 4각형 모형에 대한 응력확대계수가 계산되어 기존의 유한요소법의 해와 비교되었다.

An Integral Equation for Kinked Cracks in Finite Plane Bodies (유한영역에서의 꺾인균열 해석을 위한 적분방정식 적용 연구)

  • 서욱환
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.9
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    • pp.2138-2144
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    • 1993
  • An integral equation representation of cracks was presented which differs from well-known "dislocation layer" representation. In this new representation, the equations are written in terms of the displacement discontinuity across the crack surfaces rather than derivatives of the displacement-discontinuity. It was shown in that the new technique is well-suited to the treatment of kinked cracks. In the present paper, this integral equation representation is coupled to the direct boundary-element method for the treatment of finite bodies containing kinked cracks. The method is demonstrated for two-dimensional finite domains but extension to three-dimensional problems would appear to be possible. The resulting approach is shown to be simple, yet very accurate. accurate.

AN INTEGRAL EQUATION FOR KINKED CRACKS APPLIED TO MODE III IN FINITE PLANE BODIES (유한영역에서의 모드 III 꺾인균열 해석을 위한 적분방정식 적용연구)

  • Sur, Ukhwan
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.2 no.1
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    • pp.111-129
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    • 1998
  • An integral equation representation of cracks was presented, which differs from well-known "dislocation layer" representation. In this new representation, an integral equation representation of cracks was developed and coupled to the direct boundary-element method for treatment of cracks in plane finite bodies. The method was developed for in-plane(modes I and II) loadings only. In this paper, the method is formulated and applied to mode III problems involving smooth or kinked cracks in finite region. The results are compared to exact solutions where available and the method is shown to be very accurate despite of its simplicity.

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Application of Initial Stress Method on Elasto-plastic Problem in Boundary Element Method (경계요소법의 탄소성문제에 대한 초기응력법의 적용)

  • Soo, Lyong-Lee
    • Journal of the Society of Naval Architects of Korea
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    • v.43 no.6
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    • pp.683-692
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    • 2006
  • The BEM, known as solving boundary value problems, could have some advantages In solving domain problems which are mostly solved by FEM and FDM. Lately, in the elastic-plastic nonlinear problems, BEM could provide the subdomain approach for the region where the plastic deformation could occur and the unknown nodal displacement of this region are added as the unknown of the boundary integral equation for this approach. In this paper, initial stress method was used to establish the formulation of such BEM approach. And a simple rectangular plate having a circular hole was analyzed to verify the suggested method and the result is compared with that from FEM. It is shown that the result of two methods are showing similar stress-strain curves at the root of perforated plate and furthermore the plastic deformation obtained by BEM shows more reasonable behavior than that of FEM.