• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.70-73
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• 2006

Mesh generation for the region of interest is prerequisite for numerical analysis of governing partial differential equations describing phenomena with proper physic. Mesh generation is, however, usually considered as a major obstacle for a routine application of numerical approaches in Engineering applications. Therefore automatic mesh generation is highly pursued. In this paper automated quadrilateral surface mesh generation is proposed. According to the present method, Cartesian cells of proper resolution for a region bounding the whole region of interest are first generated and the interior cells are identified. Then projecting their surface meshes onto the boundary surfaces gives surface mesh consisting of quadrilateral cells. This method has been implemented as an application program, and example cases are given.

• 소성∙가공
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• 제15권3호
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• pp.189-194
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• 2006

In this paper, an automated adaptive mesh generation scheme, based on an advancing-front-Delaunay method, is presented fur finite element simulation of three dimensional bulk metal farming processes. Basic approach is introduced in detail, including a surface meshing and volume meshing technique and a mesh density control scheme. The presented approach is applied to automatic forging simulation in order to evaluate the effect of the developed schemes. Comparison shows a good agreement between required mesh density and generated mesh density, implying that the presented approach is appropriate for automatic mesh generation in metal forming simulation.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 춘계 학술대회논문집
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• pp.103-107
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• 2007

Computational Fluid Dynamics (CFD in short) approach is now playing an important role in the engineering process recently. Generating proper grid system for the region of interest in time is prerequisite for the efficient numerical calculation of flow physics using CFD approach. Grid generation is, however, usually considered as a major obstacle for a routine and successful application of numerical approaches in the engineering process. CFD approach based on the unstructured grid system is gaining popularity due to its simplicity and efficiency for generating grid system compared to the structured grid approaches. In this paper an automated triangular surface grid generation using CAD surface data is proposed According to the present method, the CAD surface data imported in the STL format is processed to identify feature edges defining the topology and geometry of the surface shape first. When the feature edges are identified, node points along the edges are distributed. The initial fronts which connect those feature edge nodes are constructed and then they are advanced along the CAD surface data inward until the surface is fully covered by triangular surface grid cells using Advancing Front Method. It is found that this approach can be implemented in an automated way successfully saving man-hours and reducing human-errors in generating triangular surface grid system.

• 한국전산유체공학회지
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• 제12권4호
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• pp.68-73
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• 2007

Computational Fluid Dynamics (CFD) approach is now playing an important role in the engineering process in these days. Generating proper grid system in time for the region of interest is prerequisite for the efficient numerical calculation of flow physics using CFD approach. Grid generation is, however, usually considered as a major obstacle for a routine and successful application of numerical approaches in the engineering process. CFD approach based on the unstructured grid system is gaining popularity due to its simplicity and efficiency for generating grid system compared to the structured grid approaches, especially for complex geometries. In this paper an automated triangular surface grid generation using CAD(Computer Aided Design) surface data is proposed. According to the present method, the CAD surface data imported in the STL(Stereo-lithography) format is processed to identify feature edges defining the topology and geometry of the surface shape first. When the feature edges are identified, node points along the edges are distributed. The initial fronts which connect those feature edge nodes are constructed and then they are advanced along the CAD surface data inward until the surface is fully covered by triangular surface grid cells using Advancing Front Method. It is found that this approach can be implemented in an automated way successfully saving man-hours and reducing human-errors in generating triangular surface grid system.

• 전산구조공학
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• 제9권3호
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• pp.145-155
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• 1996

이 논문은 평면 상의 영역 경계와 조절선(control curve)에 맞추어서 요소망을 자동 생성하는 알고리즘을 제시하는데 목적이 있다. 여기서 제안하는 알고리즘은 요소망 생성 영역의 경계와 조절선들을 하나의 수퍼 루프(super loop)로 연결하고, 루프(loop)위에 있는 두 절점을 연결하는 최소벌점(minimum penalty)의 경로를 따라서 순환적으로 분할하여 요소를 생성하는 기법에 바탕을 두고 있다. 이 방법은 요소망 생성영역의 형상에 제한이 없으며, 모든 과정을 쉽게 자동화 할 수 있기 때문에 복잡한 영역의 요소망을 최소한의 사용자 개입을 통해서 간편하게 처리할 수 있는 프로그램으로 쉽게 이행할 수 있다. 이 알고리즘은 곡면 요소망 생성이나, 적응적 요소망 생성등에 쉽게 확장하여 적용할 수 있다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.496-500
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• 1997

This paper describes an automated system for analyzing the stress intensity factors(SIFs) of three-dimensional (3D) cracks. A geometry model, i.e.a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-noded quadratic tetrahedral solid elements are generated by the Delauuay triangulation techniques. The singular elements such that the mid-point nodes near crack fornt are shifted at the quarter-points are automatically placed along the 3D crack front. THe complete finite element (FE) model generated, i.e the mesh with material properties and boundary conditions is given to one of the commercial FE codes, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performance of the present system, a semi- elliptical surface crack in a plate subjected to tension is solved.

• 한국정밀공학회지
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• 제14권6호
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• pp.64-73
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• 1997

솔리드 모델러, 자동요소분할 기법, 4면체 특이요소, 응력확대계수의 해석 기능을 통합하여, 3차원 균열의 응력확대계수를 효율적으로 해석할 수 있는 시스템을 개발하였다. 균열을 포함하는 기하모델을 CAD 시스템을 이용하여 정의하고, 경계조건과 재료 물성치 및 절점밀도 분포를 기하모델에 직접 지정함으로써, 퍼지이론 에 의한 절점발생과 데로우니 삼각화법에 의한 요소가 자동으로 생성된다. 특히, 균열 근방에는 4면체 2차 특이요소를 생성시켰으며, 유한요소 해석을 위한 입력 데이터가 자동으로 작성되어 해석코드에 의한 응력 해석이 수행된다. 해석 후, 출력되는 변위를 이용하여 변위외삽법에 의한 응력확대계수가 자동적으로 계산되어 진다. 본 시스템의 효용성을 확인하기 위해, 인장력을 받는 평판내의 표면균열에 대해 해석하여 보았다.

• 한국정밀공학회지
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• 제17권7호
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• pp.74-79
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• 2000

Integrating a 3D solid modeler with a general purpose FEM code, an automatic nonlinear analysis system of the 3D crack problems has been developed. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-noded quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. The complete finite element(FE) model generated, and a stress analysis is performed. In this system, burden to analysts fur introducing 3D cracks to the FE model as well as fur estimating their fracture mechanics parameters can be dramatically reduced. This paper describes the methodologies to realize such functions, and demonstrates the validity of the present system.