• 제목/요약/키워드: Finite Element method

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An Automated Adaptive Finite Element Mesh Generation for Dynamics

  • Yoon, Chongyul
    • 한국지진공학회논문집
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    • 제23권1호
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    • pp.83-88
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    • 2019
  • Structural analysis remains as an essential part of any integrated civil engineering system in today's rapidly changing computing environment. Even with enormous advancements in capabilities of computers and mobile tools, enhancing computational efficiency of algorithms is necessary to meet the changing demands for quick real time response systems. The finite element method is still the most widely used method of computational structural analysis; a robust, reliable and automated finite element structural analysis module is essential in a modern integrated structural engineering system. To be a part of an automated finite element structural analysis, an efficient adaptive mesh generation scheme based on R-H refinement for the mesh and error estimates from representative strain values at Gauss points is described. A coefficient that depends on the shape of element is used to correct overly distorted elements. Two simple case studies show the validity and computational efficiency. The scheme is appropriate for nonlinear and dynamic problems in earthquake engineering which generally require a huge number of iterative computations.

Natural vibration analysis of coaxial shells coupled with fluid

  • Jhung, Myung Jo;Choi, Young Hwan;Jeong, Kyeong Hoon
    • Structural Engineering and Mechanics
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    • 제16권6호
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    • pp.655-674
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    • 2003
  • Investigated in this study are the natural vibration characteristics of the coaxial cylindrical shells coupled with a fluid. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier series expansion, and their results are compared with those of finite element method to verify the validation of the method developed. The effect of the fluid-filled annulus and the boundary conditions on the modal characteristics of the coaxial shells is investigated using a finite element modeling.

Modal analysis of eccentric shells with fluid-filled annulus

  • Jhung, Myung Jo;Jeong, Kyeong Hoon;Hwang, Won Gul
    • Structural Engineering and Mechanics
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    • 제14권1호
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    • pp.1-20
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    • 2002
  • Investigated in this study are the modal characteristics of the eccentric cylindrical shells with fluid-filled annulus. Theoretical method is developed to find the natural frequencies of the shell using the finite Fourier expansion, and their results are compared with those of finite element method to verify the validation of the method developed. The effect of eccentricity on the modal characteristics of the shells is investigated using a finite element modeling.

C-1 유한 요소법에 의한 자계해석에 관한 연구 (alysis by C-1 Finite Element Method)

  • 임달호;김생수;김규탁
    • 대한전기학회논문지
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    • 제37권1호
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    • pp.18-24
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    • 1988
  • Up to date, C-0 Finite Element Method which is the means for analyzing electric machinery can not be got the precision magnetic flux density because the magnetic flus density has the discontinuity in the interelement. To supplement this defect, we propose the C-1 finite element method of 9 D.O.F. in this paper. In this method, the vector potential and the magnetic flux density are continuous on the interelement and direction derivative of potential would be an unknown value. We developed the algorithm to apply this method. For examining the utility, we applied this method to analytic model and compared with the result of C-0 Finite Element Method using linear element.

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3차원 케이블망의 초기평형상태 결정 및 정적 비선형 유한요소해석 (Static Non-linear Finite Element Analysis of Spatial Cable Networks)

  • 김문영;김남일;안상섭
    • 전산구조공학
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    • 제11권1호
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    • pp.179-190
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    • 1998
  • 두개의 케이블요소를 이용한 3차원 케이블망의 정적 비선형 유한요소해석기법을 제시한다. 먼저, 공간 트러스요소와 탄성현수선 케이블요소(elastic catenary cable element)의 접선강도행렬과 질량행렬을 유도하는 과정을 간략히 요약한다. 지점 변위를 일으키고 자중을 받는 케이블망의 초기평형 상태를 결정하기 위하여, Newton-Raphson 반복법에 근거한 하중증분법과 현수케이블요소를 적용하는 경우에 viscous damping을 고려한 dynamic relaxation법을 제시한다. 또한 초기의 정적평형상태를 기준으로 추가하중에 대한 케이블망의 정적 비선형해석을 수행한다. 지점변위와 외력을 받는 케이블 구조에 대하여 비선형해석을 수행하고, 해석결과들을 기존의 문헌의 결과와 비교, 검토하므로써 본 논문에서 제시한 이론 및 해석방법의 타당성을 입증한다.

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히스테리시스 특성을 고려한 전자계의 유한 요소 해석 (Finite Element Analysis of Electromagnetic Systems Considering Hysteresis Characteristics)

  • 김홍규;홍선기;정현교
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제48권3호
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    • pp.118-123
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    • 1999
  • This paper describes the finite element procedure including the magnetic hysteresis phenomena. The magnetization-dependent Preisach model is employed to simulate the magnetic hysteresis and applied to each elements. Magnetization is calculated by the Fibonacci search method for the applied field in the implementation of the magnetization-dependent model. This can calculate the magnetization very accurately with small iteration numbers. The magnetic field intensity and the magnetization corresponding to the magnetic flux density obtained by the finite element analysis(FEA) are computed at the same time under the condition that these balues must satisfy the constitutive equation. In order to reduce the total calculation cost, pseudo-permeability is used for the input for the FEA. It is found that the presented method is very useful in combining the hysteresis model with the finite element method.

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LARGE TIME-STEPPING METHOD BASED ON THE FINITE ELEMENT DISCRETIZATION FOR THE CAHN-HILLIARD EQUATION

  • Yang, Yanfang;Feng, Xinlong;He, Yinnian
    • Journal of applied mathematics & informatics
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    • 제29권5_6호
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    • pp.1129-1141
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    • 2011
  • In this paper, a class of large time-stepping method based on the finite element discretization for the Cahn-Hilliard equation with the Neumann boundary conditions is developed. The equation is discretized by finite element method in space and semi-implicit schemes in time. For the first order fully discrete scheme, convergence property is investigated by using finite element analysis. Numerical experiment is presented, which demonstrates the effectiveness of the large time-stepping approaches.

3 차원 유한요소법을 이용한 AISI 304 표면용접평판의 잔류응력해석 (Residual Stress Analysis of AISI 304 Surface Welding Plate by 3D Finite Element Method)

  • 이경수;김태룡;김만원;박재학
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회A
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    • pp.390-395
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    • 2008
  • This study is performed to understand three dimensional characteristics of weld residual stress for the surface weld on the stainless steel plate. AISI 304 plate with one path weld on the surface was used as a test specimen. Finite element analysis was done to analyze thermal transient and residual stress due to weld. The result of finite element analysis was validated by previous paper and measurement data. Among various techniques for residual stress measurement, instrumented ball indentation method was applied. The calculated residual stresses by finite element analysis showed good agreement with the measured results.

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형상압연시 연성파괴의 탄소성 유한요소해석 (The Elasto-Plastic Finite Element Analysis of Ductile Fracture in Shape Rolling)

  • 원영목;오규환
    • 소성∙가공
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    • 제5권1호
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    • pp.72-80
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    • 1996
  • During the shape rolling process the influence of reduction ration and taper of shape roller on deformation and limit of ductile fracture such as free surface cracks developing in the workpiece has been studied. The deformation behaviours were analyzed by the 3-dimensional elasto-pastic finite element method and the conditions of ductile fracture were determined from 3-dimensional elasto-plastic finite element method and modified Cockrogt-Latham criterion. The deformed geometry and prediction of ductile fracture by 3-dimensional elasto-plastic finite element method are compared with experimental results The calcuated results are in good agreements with experimental data. The analysis used in the study was found to be effective in predicting the shape rolling process.

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풍력발전 시스템용 유도발전기의 동특성 해석 (Dynamic characteristics analysis of wind-power generator rotor- bearing system)

  • 정순철;김덕수;이재응;고장욱;차종환;오시덕
    • 한국소음진동공학회:학술대회논문집
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    • 한국소음진동공학회 2001년도 추계학술대회논문집 II
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    • pp.1032-1039
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    • 2001
  • In this paper, modal analysis of wind-power generator rotor system was performed by using finite element method. Experimental modal analysis of generator rotor system was performed and the result were compared with analytical ones. Sensitivity method and localized modification method were used to update finite element model. As a result of updating finite element model, errors of natural freguency were reduced within 0.5% and MAC value was improved near by l. Stability characteristics of wind-power generator rotor-bearing system through harmonic analysis about several external force will be analyzed using finite element model.

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