• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1730-1740
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• 2006

A nodeless variables finite element method for analysis of two-dimensional, steady-state viscous incompressible flow is presented. The finite element equations are derived from the governing Navier-Stokes differential equations and a corresponding computer program is developed. The proposed method is evaluated by solving the examples of the lubricant flow in journal bearing and the flow in the lid-driven cavity. An adaptive meshing technique is incorporated to improve the solution accuracy and, at the same time, to reduce the analysis computational time. The efficiency of the combined adaptive meshing technique and the nodeless variables finite element method is illustrated by using the example of the flow past two fences in a channel.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1565-1568
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• 2003

The backward extrusion process is one of the commonly used metal forming processes. In this paper. a battery case which has the rectangular section, is analyzed using a 3D metal forming package(MSC.Superforge). This pacakge uses the finite volume analysis method. It is shown that the MSC.Superforge package using finite volume method provides result very close to those obtained from a finite element analysis package(MSC.Superform). However, the simulation time using the finite volume method was almost 10 % of the simulation time consumed by the other package using finite element method. Moreover, the finite volume method used in MSC.Superforge can eliminate the remeshing problems that make the simulating a metal forming process with severe deformation, such as the extrusion process, so difficult.

• Advances in Computational Design
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• v.9 no.3
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• pp.213-227
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• 2024

In this study, a framework for coupling of the convolution quadrature time-domain boundary element method (CQBEM) and image-based finite element method (IMFEM) is presented for 2-D elastic wave propagation. This coupling method has three advantages: 1) the finite element modeling for heterogeneous areas can be performed without difficulties by using digital data for the analysis model, 2) wave propagation in an infinite domain can be calculated with high accuracy by using the CQBEM, and 3) a small time-step size can be used. In general, a small time-step size cannot be used in the classical time-domain boundary element method. However, the CQBEM used in this analysis can address a small time-step size. This makes it possible to couple the CQBEM and image-based FEM which require a small-time step size. In this study, the formulation and validation of the pro-posed method are described and confirmed by solving fundamental elastic wave scattering problems. As a numerical example, elastic wave scattering in inhomogeneous media is demonstrated using the proposed coupling method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.11
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• pp.1192-1201
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• 2009

Analysis of the vibration characteristic for cylindrical shell is more complex than plates since the coupling effects are considered on three dimensions. Based on Love's equation, spectral finite element method(SFEM) is introduced to predict frequency response function of finite circular cylindrical shell in the air with simply supported - free boundary condition without simplifying the equation of motion. And for the radiated noise analysis of cylindrical shell, indirect boundary element method(BEM) is applied using out-of-plane displacements as an input from structural vibration analysis. Comparisons of the structural vibration results by the spectral finite element method and commercial code, NASTRAN(FEM based) are carried out. Likewise, for verification of radiated noise analysis results, commercial code, SYSNOISE(BEM based) are used.

• Structural Engineering and Mechanics
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• v.21 no.4
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• pp.437-450
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• 2005

In this study, a complete analysis of soil-structure interaction problems is presented which includes a modelling of the near surrounding of the building (near-field) and a special description of the wave propagation process in larger distances (far-field). In order to reduce the computational effort which can be very high for time domain analysis of wave propagation problems, a special approach based on similarity transformation of the infinite domain on the near-field/far-field interface is applied for the wave radiation of the far-field. The near-field is discretised with standard Finite Elements, which also allows to introduce non-linear material behaviour. In this paper, a new approach to calculate the involved convolution integrals is presented. This approximation in time leads to a dramatically reduced computational effort for long simulation times, while the accuracy of the method is not affected. Finally, some benchmark examples are presented, which are compared to a coupled Finite Element/Boundary Element approach. The results are in excellent agreement with those of the coupled Finite Element/Boundary Element procedure, while the accuracy is not reduced. Furthermore, the presented approach is easy to incorporate in any Finite Element code, so the practical relevance is high.

• Journal of the Korean Geotechnical Society
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• v.15 no.5
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• pp.19-28
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• 1999

In this paper, an application of finite element procedure for the analysis of slope failure behavior has been studied. The most widely accepted methods in analyzing the slope stability problems are mostly based on limit equilibrium method. And the finite element method is widely accepted to analyze stress and displacements. This paper shows how the factor of safety calculated in the finite element method can be systematically incorporated into slope stability. In analyzing the slope failure behavior by finite element method, the effects of computational method and the results have been discussed. And several computations of slope stabilities were carried out to compare the finite element analysis results with those obtained by methods of slices based on the limit equilibrium analysis.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.124-129
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• 2004

Finite element alternating method have been suggested and used for assessing the integrity of cracked structures. In the paper, in order to analyze arbitrarily shaped three dimensional cracks, the finite element alternating method is extended. The cracks are modeled as a distribution of displacement discontinuities by the displacement discontinuity method and the symmetric Galerkin boundary element method. Applied the proposed method to three dimensional crack included in the elbow, the efficiency and applicability of the method were demonstrated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1593-1600
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• 2000

A method based on frequency domain approaches is presented for the nonlinear parameters identification of structure having nonlinear joints. The finite element model of linear substructure is us ed to calculating its frequency response functions needed in parameter identification process. This method is easily applicable to a complex real structure having nonlinear elements since it uses the frequency response function of finite element model. Since this method is performed in frequency domain, the number of equations required to identify the unknown parameters can be easily increased as many as it needed, just by not only varying excitation amplitude but also selecting excitation frequencies. The validity of this method is tested numerically and experimentally with a cantilever beam having the nonlinear element. It was verified through examples that the method is useful to identify the nonlinear parameters of a structure having arbitary nonlinear boundaries.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.39-46
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• 2006

This paper analyzes the continuous Galerkin method for the space-time discretization of wave equation. The method of space-time finite elements enables the simple solution than the usual finite element analysis with discretization in space only. We present a discretization technique in which finite element approximations are used in time and space simultaneously for a relatively large time period called a time slab. The weighted residual process is used to formulate a finite element method for a space-time domain. Instability is caused by a too large time step in successive time steps. A stability problem is described and some investigations for chosen types of rectangular space-time finite elements are carried out. Some numerical examples prove the efficiency of the described method under determined limitations.

• 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.