• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.467-470
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• 2005

There are about 10 motors for tile actuator of the automation system in an auto-mobile recently. The performance of the motor-case is much related to the noise and the vibration of an auto-mobile Multi-Forming process is so much the better than existing deep-drawing or Multi-step forming by press by less cost, installation and staff. But there isn't the specific and general process design, so we aren't good at competition. So in the first step, I want to study about the core design for the multi-forming process. We can access by the elasto-plastic theory and the finite element method, and we use a commercial package of the Deform-2D and, Deform-3D which is based on three-dimensional elasto-plastic finite element, evaluated propriety oi the package. The evaluation of the package propriety was simulated by simple bending example. It was found the elasto-plastic theory was mostly in agreement with the simulation. We proposed that three type of section for the core and analyzed by finite element method (Deform-2D). We can get the best result with the ellipse type core. Then we apply the result of the preceding analysis to the finite element method (Deform-3D). In 3D-finite element analysis, we can get the result of 8/100mm-roundness. This result can help the improvement of the multi-forming process.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.9
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• pp.921-927
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• 1990

This paper presents a mesh refinement scheme for 3-D adaptive finite element method. Firstly, the refinement of triangular meshes based on the bisection of triangles is discussed. And a new method to refine tetrahedral meshes employing the bisection method is presented. In two dimensional cases, it has been noted that all angles in the triangular meshes refined by the bisection method are greater than or equal to half the smallest angle in the original meshes. Through the examples where the newly proposed method is applied to three dimensional cases, it is shown that regarding the solid angles, the method gives nearly the same result as that in the two dimensional case. Accordingly, it can be concluded that the proposed method will be useful in the mesh refinements for 3-D adaptive finite element method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.6
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• pp.607-613
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• 2010

FRANC3D is a program for simulating arbitrary three-dimensional crack growth. Recently, a completely new version of the program, FRANC3D/NG, has been created. Unlike previous versions, which relied largely on boundary element analysis, the new version of the program works with finite element analysis exclusively and is designed to work with general-purpose commercial finite element packages. This paper presents the theoretical underpinnings of the procedures to adaptively modify the geometry and mesh of a model to simulate crack growth.

• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.319-328
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• 2006

A simple approximation method for the stress intensity factor at the tip of the axial semielliptical cracks on the cylindrical vessel is developed. The approximation methods, incorporated in VINTIN (Vessel INTegrity analysis-INner flaws), utilizes the influence coefficients to calculate the stress intensity factor at the crack tip. This method has been compared with other solution methods including 3-D finite element analysis for internal pressure, cooldown, and pressurized thermal shock loading conditions. For these, 3-D finite-element analyses are performed to obtain the stress intensity factors for various surface cracks with t/R=0.1. The approximation solutions are within $\pm2.5%$ of the those of finite element analysis using symmetric model of one-forth of a vessel under pressure loading, and 1-3% higher under pressurized thermal shock condition. The analysis results confirm that the approximation method provides sufficiently accurate stress intensity factor values for the axial semi-elliptical flaws on the surface of the reactor pressure vessel.

• Structural Engineering and Mechanics
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• v.43 no.4
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• pp.411-437
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• 2012

In this paper, we propose a continuum mechanics based 3-D beam finite element with cross-sectional discretization allowing for warping displacements. The beam element is directly derived from the assemblage of 3-D solid elements, and this approach results in inherently advanced modeling capabilities of the beam element. In the beam formulation, warping is fully coupled with bending, shearing, and stretching. Consequently, the proposed beam elements can consider free and constrained warping conditions, eccentricities, curved geometries, varying sections, as well as arbitrary cross-sections (including thin/thick-walled, open/closed, and single/multi-cell cross-sections). We then study the modeling and predictive capabilities of the beam elements in twisting beam problems according to geometries, boundary conditions, and cross-sectional meshes. The results are compared with reference solutions obtained by analytical methods and solid and shell finite element models. Excellent modeling capabilities and solution accuracy of the proposed beam element are observed.

• Transactions of Materials Processing
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• v.21 no.4
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• pp.252-257
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• 2012

Crystallographic texture evolution during forming processes has a significant effect on the anisotropic flow behavior of crystalline material. In this study, a crystal plasticity finite element method (CPFEM), which incorporates the crystal plasticity constitutive law into a three-dimensional finite element method, was used to investigate texture evolution of a face-centered-cubic material - an aluminum alloy. A rate-dependent polycrystalline theory was fully implemented within an in-house program, CAMPform3D. Each integration point in the element was considered to be a polycrystalline aggregate consisting of a large number of grains, and the deformation of each grain in the aggregate was assumed to be the same as the macroscopic deformation of the aggregate. The texture evolution during three different deformation modes - uniaxial tension, uniaxial compression, and plane strain compression - was investigated in terms of pole figures and compared to experimental data available in the literature.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2D
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• pp.135-141
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• 2010

Dowel bar in the jointed concrete pavement has been designed and constructed by Foreign standard and experience in Korea. The behavior of dowel bar is explored based in analyze of 3-Dimension Finite Element Method. To evaluate behavior of dowel bar compared Timoshenko theory and 3-Dimensional Finite Element Method. Based on the 3-Dimension Finite Element Method analyze the dowel-bar optimum position that can reduce deflections of slabs by considering wheel path distributions was suggest in this study.

• Advances in Computational Design
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• v.5 no.3
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• pp.277-289
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• 2020

This article describes the technology for constructing of a multiply-connected three-dimensional area's finite element representation. Representation of finite-element configuration of an area is described by a discrete set that consist of the number of nodes and elements of the finite-element grid, that are orderly set of nodes' coordinates and numbers of finite elements. Corresponding theorems are given, to prove the correctness of the solution method. The adequacy of multiply-connected area topology's finite element model is shown. The merging of subareas is based on the criterion of boundary nodes' coincidence by establishing a simple hierarchy of volumes, surfaces, lines and points. Renumbering nodes is carried out by the frontal method, where nodes located on the outer edges of the structure are used as the initial front.

• Transactions of Materials Processing
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• v.24 no.3
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• pp.161-166
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• 2015

The finite element method has been widely used in the analysis of ring rolling. For ring rolling it requires a high computational expense due to the non-steady state material flow characteristics of the process. The high computational expense causes the finite element analysis to be impractical for industrial applications. In the current study, we aim to develop a practical implicit finite element modeling method for ring rolling. This method uses a step-wise steady state assumption and is called the “Stepped method”. The stepped method divides the whole process time of unsteady-state flow model into a finite number of steady-state models. It then solves the process at several specific time steps until convergence is reached. In order to confirm the performance and validity of the newly proposed stepped method, the result from the stepped method were compared to the results from a Lagrangian finite element method and to results from experiments reported in the literature.

• Transactions of Materials Processing
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• v.12 no.3
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• pp.194-201
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• 2003

An automatic quadrilateral mesh generator for large deformation finite element analysis such as metal forming simulation was developed. The NURBS interpolation method is used for modeling arbitrary 2-D free surface. This mesh generation technique is the modified paving algorithm, which is an advancing front technique with element-by-element resolving method for paving boundary intersection problem. The mesh density for higher analysis accuracy and less analysis time can be easily controlled with high-density points, maximum and minimum element size. A couple of application to large deformation finite element analysis is given as an example, which shows versatility and applicability of the proposed approach and the developed mesh generator for large deformation finite element analysis.