• Computational Structural Engineering
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• v.7 no.3
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• pp.167-176
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• 1994

A local remeshing algorithm using Delaunay property is developed for the analysis on the phenomenon of quasi-static crack propagation, which is a typical problem of accompanying constantly varying geometry. The algorithm performs both remeshing and refinement. The use of M-integral is demonstrated to simulate crack propagation under mixed mode with the edge spalling problem.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.1926-1932
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• 2001

In this second part of the paper, the automatic mesh generation and remeshing algorithm using bubble packing method is applied to the nonlinear problem. The remeshing/refinement procedure is necessary in the large deformation process especially because the mesh distortion deteriorates the convergence and accuracy. To perform the nonliear analysis, the transfer of state variables such as displacement and strain is added to the algorithm of Part 1. The equilibrium equation based on total Lagrangian formulation and elasto-viscoplastic model is used. For the numerical experiment, the upsetting process including the contact constraint condition is analyzed by two refinement criteria. And from the result, it is addressed that the present algorithm can generate the refined meshes easily at the largely deformed area with high error.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.10a
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• pp.62-65
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• 2000

For saving time and cost of experiment Finite Element Method has been developed for several decades. It's the defect of FEM that when we are in processing of finite element analysis, the material if deformed so much that we can't proceed analysis any more. In this case, the remeshing process should be done on this material. In hot forging process, almost all remeshing process does not consider flash of the material. Because as mesh size become swatter, consuming time become larger. But if mesh size is big, there is the defect that the result of analysis is not so accurate. So, new remeshing algorithm is needed to save time and to get more accurate result.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.2
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• pp.553-563
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• 1996

An algorithm for automatic mesh generation of two-dimensional arbitrary planar domain is proposed by using Delaunay triangulation algorithm. An efficient algorithm is proposed for the construction of Delaunay triangulation algorithm over convex planar domain. From the definition of boundary, boundary nodes are first defined and then interior nodes are generated ensuring the Delaunay property. These interior nodes and the boundary nodes are then linked up together to produce a valid triangular mesh for any finite element analysis. Through the various example, it is found that high-quality triangular element meshes are obtained by Delaunay algorithm, showing the robustness of the current method. The proposed mesh generation scheme has been extended to automatic remeshing, which is applicable to FE analysis including large deformation and large distortion of elements.

• International Journal of Fluid Machinery and Systems
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• v.9 no.4
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• pp.287-299
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• 2016

In China, agricultural irrigation water often contains a lot of suspended sediment which may cause the nozzle wear. In this study, a new numerical simulation combing the Discrete Phase Model and a remeshing algorithm was conducted. The geometric boundary deformation caused by the erosion wear, was considered. The weight loss of the nozzle, the node displacement and the flow field were investigated and discussed. The timestep sensitivity analysis showed that the timestep is very critical in the erosion modeling due to the randomness and the discreteness of the erosion behavior. Based on the simulation results, the major deformation of the boundary wall due to the erosion was found at the corners between outlet portion and contraction portion. Based on this remeshing algorithm, the simulated erosion weight loss of the nozzle is 4.62% less compared with the case without boundary deformation. The boundary deformation changes the pressure and velocity distribution, and eventually changes the sediment distribution inside the nozzle. The average turbulence kinetic energy at the outlet orifice is found to decrease with the erosion time, which is believed to change the nozzle's spray performance eventually.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.1004-1014
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• 2001

The fully automatic algorithm from initial finite element mesh generation to remeshing in two dimensional geometry is introduced using bubble packing method (BPM) for finite element analysis. BPM determines the node placement by force-balancing configuration of bubbles and the triangular meshes are made by Delaunay triangulation with advancing front concept. In BPM, we suggest two node-search algorithms and the adaptive/recursive bubble controls to search the optimal nodal position. To use the automatically generated mesh information in FEA, the new enhanced bandwidth minimization scheme with high efficiency in CPU time is developed. In the remeshing stage, the mesh refinement is incorporated by the control of bubble size using two parameters. And Superconvergent Patch Recovery (SPR) technique is used for error estimation. To verify the capability of this algorithm, we consider two elasticity problems, one is the bending problem of short cantilever beam and the tension problem of infinite plate with hole. The numerical results indicate that the algorithm by BPM is able to refine the mesh based on a posteriori error and control the mesh size easily by two parameters.

• Korean Journal of Computational Design and Engineering
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• v.6 no.3
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• pp.184-192
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• 2001

In this paper we present a remeshing algorithm for irregular meshes with boundaries. The irregular meshes are approximated by regular meshes where the topological regularity is essential for the multiresolutional analysis of the given meshes. Normal meshes are utilized to reduce the necessary data size at each resolution level of the regularized meshes. The normal mesh uses one scalar value, i.e., normal offset value which is based on the regular rule of a uniform subdivision, while other remeshing schemes use one 3D vector at each vertex. Since the normal offset cannot be properly used for the boundaries of meshes, we use a combined subdivision scheme which resolves a problem of the proposed normal offset method at the boundaries. Finally, we show an example to see the effectiveness of the proposed scheme to reduce the data size of a mesh model.

• Korean Journal of Computational Design and Engineering
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• v.12 no.4
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• pp.255-262
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• 2007

In the finite element analysis of forming process, objects are described with a finite number of elements and nodes and the approximated solutions can be obtained by the variational principle. One of the shortcomings of a finite element analysis is that the structure of mesh has become inefficient and unusable because discretization error increases as deformation proceeds due to severe distortion of elements. If the state of current mesh satisfies a certain remeshing criterion, analysis is stopped instantly and resumed with a reconstructed mesh. In the study, a new remeshing algorithm using tetrahedral elements has been developed, which is adapted to the desired mesh density. In order to reduce the discretization error, desired mesh sizes in each lesion of the workpiece are calculated using the Zinkiewicz and Zhu's a-posteriori error estimation scheme. The pre-constructed mesh is constructed based on the modified point insertion technique which is adapted to the density function. The object domain is divided into uniformly-sized sub-domains and the numbers of nodes in each sub-domain are redistributed, respectively. After finishing the redistribution process of nodes, a tetrahedral mesh is reconstructed with the redistributed nodes, which is adapted to the density map and resulting in good mesh quality. A goodness and adaptability of the constructed mesh is verified with a testing measure. The proposed remeshing technique is applied to the finite element analyses of forging processes.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.159-162
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• 2003

The remeshing algorithm using the constrained Delaunay method adapted to the mesh density map is developed. In the finite element simulation of forging process, the numerical error increases as the process goes on. However, it is not desirable to use a uniformly fine mesh in the whole domain. Therefore, it is necessary to reduce the analysis error by constructing locally fine mesh at the region where the error is concentrated such as die corner. In this paper, the point insertion algorithm is used and mesh size is controlled by using a mesh density map constructed with a posteriori error estimation. And an optimized smoothing technique is adapted to have smooth distribution and improve the quality of the mesh.

• Transactions of Materials Processing
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• v.13 no.4
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• pp.334-341
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• 2004

In this study, a remeshing algorithm adapted to the mesh density map using the Delaunay mesh generation method is developed. In the finite element simulation of forging process, the numerical error increases as the process goes on because of discrete property of the finite elements and distortion of elements. Especially, in the region where stresses and strains are concentrated, the numerical error will be highly increased. However, it is not desirable to use a uniformly fine mesh in the whole domain. Therefore, it is necessary to reduce the analysis error by constructing locally refined mesh at the region where the error is concentrated such as at the die corner. In this paper, the point insertion algorithm is used and the mesh size is controlled by using a mesh density map constructed with a posteriori error estimation. An optimized smoothing technique is adopted to have smooth distribution of the mesh and improve the mesh element quality.