• Coupled systems mechanics
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• 제4권3호
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• pp.211-235
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• 2015

In this work we present a one-dimensional damage model capable of representing the dynamic fracture for elastodamage bar with combined hardening in fracture process zone - FPZ and softening with embedded strong discontinuities. This model is compared with another one we recently introduced (Do et al. 2015) and it shows a good agreement between two models. Namely, it is indicated that strain-softening leads to a sensitivity of results on the mesh discretization. Strain tends to localization in a single element which is the smallest possible area in the finite element simulations. The strain-softening element in the middle of the bar undergoes intense deformation. Strain increases with increasing mesh refinement. Strain in elements outside the strain-softening element gradually decreases to zero.

• 한국기계가공학회지
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• 제8권3호
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• pp.21-26
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• 2009

The finite element analysis of metal forming processes often fails because of severe mesh distortion at large deformation. As the concept of meshless methods, only nodal point data are used for modeling and solving. As the main feature of these methods, the domain of the problem is represented by a set of nodes, and a finite element mesh is unnecessary. This computational methods reduces time-consuming model generation and refinement effort. It provides a higher rate of convergence than the conventional finite element methods. The displacement shape functions are constructed by the reproducing kernel approximation that satisfies consistency conditions. In this research, A meshless method approach based on the reproducing kernel particle method (RKPM) is applied with metal forming analysis. Numerical examples are analyzed to verify the performance of meshless method for metal forming analysis.

• Structural Engineering and Mechanics
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• 제3권1호
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• pp.75-89
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• 1995

A transition membrane element designated as CLM which has variable mid-side nodes with drilling freedoms has been presented in this paper. The functional for the linear problem, in which the drilling rotations are introduced as independent variables, has been formulated. The transition elements with variable side nodes can be efficiently used in the local mesh refinement for the in-plane structures, which have stress concentrations. A modified Gaussian quadrature is needed to be adopted to evaluate the stiffness matrices of these transition elements mainly due to the slope discontinuity of displacement within the elements. Detailed numerical studies show the excellent performance of the new transition elements developed in this study.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2002년도 종합학술발표회 논문집 Vol.12 No.1
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• pp.375-379
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• 2002

본 논문에서는 수 만개이상의 미지수를 필요로 하는 복잡한 3차원 구조에서의 정전용량 추출을 위한 고속화 알고리즘(Fast mutilpole method)과 결합한 효과적인 적응 삼각요소 분할법(Adaptive triangular mesh refinement algorithm)을 제안하였다. 요소세분화과정은 초기요소로 전하의 분포를 구하고, 전하밀도가 높은 영역에서의 요소세분화를 수행하여 이루어진다. 제안된 방법을 이용하여 많은 미지수를 필요로 하는 IC packaging 구조에서의 정전용량을 추출하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 가을 학술발표회논문집
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• pp.120-127
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• 1993

This paper is concerned with the integrated computer program system aiming at efficiently performing the structural analysis and design. The developed computer program system is introduced and applied to a simple two-dimensional structure to show the general concept of the integrated system. Some design modifications and re-analyses are illustrated including local mesh refinement, These show the efficiency in doing design modification and analysis.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 봄 학술발표회논문집
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• pp.3-10
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• 1993

A new three-dimensional transition solid elements was presented for the automated three-dimensional adaptive h-refinement where the steep stress gradient exists. To be consistent with 8-node solid element with nonconforming modes in accuracy, these transition elements were improved through the addition of the associated nonconforming modes. Numerical examples show that the performance of the element and the applicability to 3D adaptations are satisfactory.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1992년도 가을 학술발표회 논문집
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• pp.39-44
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• 1992

This paper is concerned with formulations of the hierarchical $C^{o}$-plate element on the basis of Reissner-Mindlin plate theory. On reason for the development of the aforementioned element is that it is still difficult to construct elements based on h-version concepts which are accurate and stable against the shear locking effects. An adaptive mesh refinement and selective p-distribution of the polynomial degree using hp-version of the finite element method we proposed to verify the superior convergence and algorithmic efficiency with the help of the clamped L-shaped plate problems.s.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1990년도 가을 학술발표회 논문집
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• pp.3-8
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• 1990

A new finite element technology based on p-version of F.E.M. is discussed with reference to its potential for application to stress intensity factor computations. In linear elastic fracture mechanics, especially cracked cylindrical shells. It is shown that the p-version nutlet is far better suited for computing the stress intensity factors than the conventional h-version models with the help of three test problems. The main advantage of this technology is that the accuracy of approximation can be established without mesh refinement or the use of special procedures.

• 한국공간구조학회논문집
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• 제12권2호
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• pp.45-53
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• 2012

본 논문은 비정형의 정확한 형상 설계와 구조해석을 위해 넙스 기저함수를 기반으로 한 변수들로 생성된 평연의 등기하 해석법과 해석 결과에 대한 후처리 방법을 제시한다. 제어점, 매듭값, 차수들로 구성되는 변수들을 인터페이스 기법을 통해 변화시킴으로써 다양한 기하 형상을 구축할 수 있다. 등기하 해석에 사용되는 기저함수는 기하형상 구축에 사용되는 함수와 동일하여 형상의 정확한 설계와 해석이 가능하다. 등기하 해석을 위한 요소망 생성을 위해 h-p-k refinement 과정을 수행함으로써 기존 형상의 변형없이 요소망을 생성하여 구조해석을 수행하였다. 해석에 의한 결과값인 제어점의 변위에 대한 시각화를 위해 IGES 포맷과 넙스기반 3D 설계 프로그램 라이노와의 인터페이스 과정을 수행하여 최종 변형 형상 표현을 위한 후처리 방법을 제시한다.

• Wind and Structures
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• 제24권3호
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• pp.223-247
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• 2017

By using numerical simulation, vast and detailed information and observation of the physics of flow over a train model can be obtained. However, the accuracy of the numerical results is questionable as it is affected by grid convergence error. This paper describes a systematic method of computational grid refinement for the Unsteady Reynolds Navier-Stokes (URANS) of flow around a generic model of trains using the OpenFOAM software. The sensitivity of the computed flow field on different mesh resolutions is investigated in this paper. This involves solutions on three different grid refinements, namely fine, medium, and coarse grids to investigate the effect of grid dependency. The level of grid independence is evaluated using a form of Richardson extrapolation and Grid Convergence Index (GCI). This is done by comparing the GCI results of various parameters between different levels of mesh resolutions. In this study, monotonic convergence criteria were achieved, indicating that the grid convergence error was progressively reduced. The fine grid resolution's GCI value was less than 1%. The results from a simulation of the finest grid resolution, which includes pressure coefficient, drag coefficient and flow visualization, are presented and compared to previous available data.