• Title/Summary/Keyword: Finite Element Method

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A Proposal of an Analytical Method for Estimating the Opening Behaviour of Tip-Closed Crack in Compressive Residual Stress by Finite Element Method (압축잔류응력에 의하여 선단부가 닫힌 균열의 개구거동에 대한 유한요소법에 의한 해석방법의 제안)

  • 김응준;박응준;유승현
    • Journal of Welding and Joining
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    • v.21 no.6
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    • pp.71-76
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    • 2003
  • For the purpose of clarifying the influence of welding residual stress to the fatigue crack propagations behaviour, an analytical investigation based on finite element method is performed to examine the opening behaviour of tip-closed crack in the compressive residual stress. A finite element model comprised of contact elements for the crack plane and plane stress elements for the base material is used to evaluate crack opening stress of the crack existing in the residual stress field. Also an analytical method based on the superposition principle to estimate the length of opened part of tip closed crack and the stress distribution adjacent to the crack during uploading is applied to the finite element model. The software for the analysis is ABAQUS, which is a general purpose finite element package. The results show that stresses distributed on the crack surfaces are reduced and approached to zero as the applied stresses are increased up to crack tip opening stress and no mechanical discontinuity is found at the boundary of contact elements and plane stress elements. It is verified that the opening behavior of the fatigue crack in the residual stress can be predicted by finite element method with the proposed analytical method.

Improvement of the finite element dynamic model by using exact dynamic elements (엄밀한 동적 요소를 이용한 유한 요소 동적 모델의 개선)

  • Cho, Yong-Ju;Kim, Jong-Wook;Hong, Seong-Wook
    • Proceedings of the KSME Conference
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    • 2001.06b
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    • pp.590-595
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    • 2001
  • To improve the modeling accuracy for the finite element method, this paper proposes a method to make a combined use of finite elements and exact dynamic elements. Exact interpolation functions for a Timoshenko beam element are derived and compared with interpolation functions of the finite element method (FEM). The exact interpolation functions are tested with the Laplace variable varied. The exact interpolation functions are used to gain more accurate mode shape functions for the finite element method. This paper also presents a combined use of finite elements and exact dynamic elements in design problems. A Timoshenko frame with tapered sections is tested to demonstrate the design procedure with the proposed method.

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Structural Dynamics Analysis of a Clamp Jointed Complex Ream by Using the Flexibility Influence Coefficient Method (유연도 영향계수법을 이용한 접촉결합부가 있는 복합구조물의 동적 해석)

  • 조재혁;김현욱;최영휴
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1995.10a
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    • pp.528-533
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    • 1995
  • An analyical method is proposed to construct a clamp jointed structure as an equivalent stiffness matrix element in the finite element modal analysis of a complex beam structure. Static structural analysis was first made for the detail finite element model of the clamp joint. Utilizing the results of this analysis, the equivalent stiffness matrix element was buildup by using the flexibility influence coefficient method and Guyan condensation. The proposed method was applied to finite element modal analysis of a clamp jointed cantilever beam. And the finite element analysis results were compared to those experimental modal analysis. Comparison shows doog agreement each other Furthermore the effects of normal contact(or clamping) load on the equivalent stiffness matrix was also examined. The equivalent stiffness matrix showed little change in spite of the remakable increase in the contact load on the clamp joint.

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A Study on the Combined Use of Exact Dynamic Elements and Finite Elements (엄밀한 동적 요소와 유한 요소 통합 해석 방법에 관한 연구)

  • 홍성욱;조용주;김종선
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.2
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    • pp.141-149
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    • 2002
  • Although the finite element method has become an indispensible tool for the dynamic analysis of structures, difficulty remains to quantify the errors associated with discretization. To improve the modeling accuracy, this paper proposes a method to make a combined use of finite elements and exact dynamic elements. Exact interpolation functions for the Timoshenko beam element are derived using the exact dynamic element modeling (EDEM) and compared with interpolation functions of the finite element method (FEM). The exact interpolation functions are tested with the Laplace variable varied. A combined use of finite element method and exact interpolation functions is presented to gain more accurate mode shape functions. This paper also presents a combined use of finite elements and exact dynamic elements in design/reanalysis problems. Timoshenko flames with tapered sections are tested to demonstrate the design procedure with the proposed method. The numerical study shows that the combined use of finite element model and exact dynamic element model is very useful.

Development of a Wall Analysis Model Grafting FE-BEM (FE-BEM을 결합한 벽체의 해석모델 개발)

  • Jung , Nam-Su;Choi, Won;Lee, Ho-Jae;Kim , Han-Joong;Lee , Jeong-Jae;Kim, Jong-Ok
    • Journal of The Korean Society of Agricultural Engineers
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    • v.46 no.5
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    • pp.61-68
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    • 2004
  • Methodologies of the finite element and boundary element are combined to achieve an efficient and accurate analysis model of frame structure containing shear wall. This model analyzes the frame by employing the finite element method and the shear wall by boundary element method. This study is applicable to a specific situation, where the boundary element is surrounded by finite elements. By employing FE dominant method in which boundary stiffness matrix is transformed into finite element stiffness matrix, boundary element and finite element method are combined to analyze frame structure with walls.

Computer Simulation of Upsetter Forging Processes that uses Finite Volume Method (유한체적법을 이용한 업셋터 단조공정의 컴퓨터 시뮬레이션)

  • Kim, H.T.;Park, S.Y.;Joun, M.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.05a
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    • pp.170-175
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    • 2007
  • The finite volume method for forging simulation is examined to reveal its possibility as well as its problem in this paper. For this study, the finite volume method based MSC/SuperForge and the finite element method based AFDEX are employed. The simulated results of the homogeneous compression obtained by the two softwares are compared to indicate the problems of the finite volume method while several application examples are given to show the possibility of the finite volume method for simulation of upsetter forging processes. It is shown that the finite volume method can not predict the exact solution of the homogeneous compression especially in terms of forming load and deformed shape but that it is helpful to simulate very complex forging processes which can hardly be simulated by the conventional finite element method.

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Finite Element Analysis for Performance Evaluation of Lightweight Piezo-composite Curved Acutator (경량 압전 작동기(LIPCA)의 작동성능 평가를 위한 유한요소 해석)

  • 구남서;박훈철;윤광준
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2000.11a
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    • pp.135-140
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    • 2000
  • A numerical method fur performance evaluation of LIPCA is proposed using a finite element method. Fully coupled formulations for piezo-electric material are introduced and eight-node incompatible element is used. After verifying the developed code, the behaviors of LIPCA and $THUNDER^{TM}$ are investigated.

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A Composite Method of Finite Element and of Boundary Integral Methods for the Magnetic Field Problems with Open Boundary (유한요소법 및 경계적분법의 혼합법에 의한 개 영역 자장문제 해석)

  • 정현교;함송엽
    • The Transactions of the Korean Institute of Electrical Engineers
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    • v.36 no.6
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    • pp.396-402
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    • 1987
  • A Composite method of finite element and boundary integral methods is introduced to solve the magnetostatic field problems with open boundary. Only the region of prime interest is taken as the compution region where the finite element method is applied. The boundary conditions of the region are dealt with using boundary integral method. The boundary integration in the boundary integral method is done by numerical and analytical techniques repectively. The proposed method is applied to a simple linear problem, and the results are compared with those of the finite element method and the analytic solutions. It is concluded that the proposed method gives more accurate results than the finite element method under the same computing efforts.

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Fatigue Crack Growth Simulation of Arbitrarily Shaped Three Dimensional Cracks Using Finite Element Alternating Method (유한요소 교호법을 이용한 임의 형상의 삼차원 균열의 피로균열 성장 해석)

  • Park, Jai-Hak;Kim, Tae-Soon
    • Journal of the Korean Society of Safety
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    • v.21 no.1 s.73
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    • pp.15-20
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    • 2006
  • The finite element alternating method is a convenient and efficient method to analyze three-dimensional cracks embedded in an infinite or a finite body because the method has the property that the uncracked body and cracks can be modeled independently. In this paper the method was applied for fatigue crack growth simulation. A surface crack in a cylinder was considered as an initial crack and the crack configurations and stress intensity factors during the crack growth were obtained. In this paper the finite element alternating method proposed by Nikishkov, Park and Atluri was used after modification. In the method, as the required solution for a crack in an infinite body, the symmetric Galerkin boundary element method formulated by Li and Mear was used. And a crack was modeled as distribution of displacement discontinuities, and the governing equation was formulated as singularity-reduced integral equations.

Quasi-brittle and Brittle Fracture Simulation Using Phase-field Method based on Cell-based Smoothed Finite Element Method (셀기반 평활화 유한요소법에 기반한 위상분야법을 이용한 준취성 및 취성 파괴 시뮬레이션)

  • Changkye Lee;Sundararajan Natarajan;Jurng-Jae Yee
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.36 no.5
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    • pp.295-305
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    • 2023
  • This study introduces a smoothed finite-element implementation into the phase-field framework. In recent years, the phase-field method has recieved considerable attention in crack initiation and propagation since the method needs no further treatment to express the crack growth path. In the phase-field method, high strain-energy accuracy is needed to capture the complex crack growth path; thus, it is obtained in the framework of the smoothed finite-element method. The salient feature of the smoothed finite-element method is that the finite element cells are divided into sub-cells and each sub-cell is rebuilt as a smoothing domain where smoothed strain energy is calculated. An adaptive quadtree refinement is also employed in the present framework to avoid the computational burden. Numerical experiments are performed to investigate the performance of the proposed approach, compared with that of the finite-element method and the reference solutions.