• Title/Summary/Keyword: Elasto-Plastic finite element analysis

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Evaluation of Computerized Methods for Stepwise Underground Excavation and Support System (지하 터파기 버팀시스템의 전산해석 사례 및 평가)

  • 장찬수;우홍기
    • Proceedings of the Korean Geotechical Society Conference
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    • 1991.10a
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    • pp.289-311
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    • 1991
  • Analysis of supported excavation system by Elasto-Plastic Isoparametric Finite Element Method and Elasto-Plastic Beam Method have been conducted for the simulation of stepwise underground excavation. Conventional methods, fixed Supported Beam and Spring Supported Beam method, also have been examined and compared with the results of elasto-plastic beam method and field data. Except unavoidable result of upward ground settlement near the top of retaining wall and relatively high bending moment of wall at each excavation level, satisfactory results have been derived using elasto-plastic isopara metric finite element method. The results from elasto-plastic beam analysis program, developed by the author, are proved to be fit field data in acceptable variance as shown in the paper. Displacement and bending moment, of the wall by conventional methods, both fixed supported beam and spring supported beam, are always underestimated than field data, and attention must be given that the diffence increases with deeper excavation depth and lower horizontal subgrade reaction of the ground.

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Investigation of seismic responses of reactor vessel and internals for beyond-design basis earthquake using elasto-plastic time history analysis

  • Lee, Sang-Jeong;Lee, Eun-ho;Lee, Changkyun;Park, No-Cheol;Choi, Youngin;Oh, Changsik
    • Nuclear Engineering and Technology
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    • v.53 no.3
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    • pp.988-1003
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    • 2021
  • Existing elastic analysis methods cannot be adhered to in order to assess the structural integrity of a reactor vessel and internals for a beyond design basis earthquake. Elasto-plastic analysis methods are required, and the factors that affect the elasto-plastic behavior of reactor materials should be taken into account. In this study, a material behavior model was developed that considers the irradiation embrittlement effect, which affects the elasto-plastic behavior of the reactor material. This was used to perform the elasto-plastic time history analyses of the reactor vessel and its internals for beyond design basis earthquake. For this investigation, appropriate beyond design basis earthquakes and reliable finite element models were used. Based on the analysis results, consideration was given to the load reduction effect and the margin change. These were transferred to the internals due to the plastic deformation of the reactor vessel.

A Study on the Mechanical Characteristics of the Resistance Multi-spot Welded Joints (저항 다점용접부의 역학적 특성에 관한 연구)

  • 방한서;방희선
    • Journal of Welding and Joining
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    • v.19 no.5
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    • pp.499-505
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    • 2001
  • In order to classify the mechanical phenomena of thermal elasto-plastic behavior on the multi-spot welded joints, this study has tried to carry out three-dimensional thermal elasto-plastic analysis on them. However, because the shape of multi-spot welded joints is not taxi-symmetric, unlike the cafe of single-spot welded joint, the solution domain for simulation should be three dimension. Therefore, in this paper, firstly, the three-dimensional thermal elasto-plastic program is developed by an iso-parametric finite element method. Secondly, from the results analyzed by developed program, this has clarified mechanical characteristics and their production mechanism on single and multi-spot waled joints. Moreover, it has been intended to make clear effects of pitch length on welding residual stresses, plastic strain of multi-spot welded joints.

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Thermo-Elasto-Plastic Finite Element Analysis of Powder Hot Forging (열간분말단조 공정의 열탄소성 유한요소해석)

  • 김형섭
    • Journal of Powder Materials
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    • v.4 no.2
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    • pp.83-89
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    • 1997
  • A finite element analysis to solve the coupled thermomechanical problem in the plane strain upsetting of the porous metals was performed. The analysis was formulated using the yield function advanced by Lee and kim and developed using the thermo-elasto-plastic time integration procedure. The density and temperature dependent thermal and mechanical properties of porous metals were considered. The internal heat generation by the plastic deformation and the changing thermal boundary conditions corresponding to the geometry were incorporated in the program. The distributions of the stress, strain, pressure, density and temperature were predicted during the free resting period, deformation period and dwelling period of the forging process.

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Optimum Design of the Process Parameter in Sheet Metal Forming with Design Sensitivity Analysis using the Direct Differentiation Approach (I) -Design Sensitivity Analysis- (직접미분 설계민감도 해석을 이용한 박판금속성형 공정변수 최적화 (I) -설계민감도 해석 -)

  • Kim, Se-Ho;Huh, Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.11
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    • pp.2245-2252
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    • 2002
  • Design sensitivity analysis scheme is proposed in an elasto -plastic finite element method with explicit time integration using a direct differentiation method. The direct differentiation is concerned with large deformation, the elasto-plastic constitutive relation, shell elements with reduced integration and the contact scheme. The design sensitivities with respect to the process parameter are calculated with the direct analytical differentiation of the governing equation. The sensitivity results obtained from the present theory are compared with that obtained by the finite difference method in a class of sheet metal forming problems such as hemi-spherical stretching and cylindrical cup deep-drawing. The result shows good agreement with the finite difference method and demonstrates that the preposed sensitivity calculation scheme is a pplicable in the complicated sheet metal forming analysis and design.

Multi-stage Analysis of Elliptic Cup Drawing Processes with the Large Aspect Ratio by an Explicit Elasto-Plastic Finite Element Method (외연적 유한요소법을 이용한 세장비가 큰 타원형 컵 성형공정의 다단계 해석)

  • Kim, S.H.;Kim, S.H.;Huh, H.
    • Transactions of Materials Processing
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    • v.9 no.3
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    • pp.313-319
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    • 2000
  • Finite element analysis is carried out for simulation of the multi-stage elliptic cup drawing process with the large aspect ratio. The analysis incorporates with shell elements for an elasto-plastic finite element method with the explicit time integration scheme. For the simulation, LS-DYNA3D is utilized for its wide capability of solving forming problems. The simulation result shows that the non-uniform drawing ratio at the elliptic cross section ad the small shoulder radius cause failure such as tearing and wrinkling. The result suggests the guideline to modify the tool shape for prevention of the failure during the drawing process.

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Analysis of Elasto-Plastic Buckling Characteristics of Plates (평면판의 탄소성 좌굴 특성 해석)

  • 김문겸;김소운;황학주
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1990.10a
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    • pp.16-21
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    • 1990
  • Recently, the finite element method has been sucessfully extended to treat the rather couplet phenomena such as nonlinear buckling problems which are of considerable practical interest. In this study, a finite element program to evaluate the elasto-plastic buckling stress is developed. The Stowell's deformation theory for the plastic buckling of flat plates, which is in good agreement with experimental results, is used to evaluate bending stiffness matrix. A bifurcation analysis is performed to compute the elasto-plastic buckling stress. The subspace iteration method is employed to find the eigenvalues. The results are compared with corresponding enact solutions to the governing equations presented by Stowell and also with experimental data due to Pride. The developed program Is applied to obtain elastic and elasto-plastic buckling stresses for various loafing cases. The effect of different plate aspect ratio is also investigated.

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Analysis on the Elasto-Plastic Thermal Stress and Deformation of Metal Casting Mould by FEM (Finite Element Method) (FEM을 이용한 주조금형(鑄造金型)의 탄소성(彈塑性) 열응력(熱應力) 및 열변형(熱變形) 해석(解析))

  • Kim, Ok-Sam;Koo, Bon-Kwon;Min, Soo-Hong
    • Journal of Korea Foundry Society
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    • v.13 no.1
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    • pp.81-93
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    • 1993
  • It is well-known that the analysis of elasto-plastic thermal stress and deformation are substantially important in optimal design of metal casting mould. The unsteady state thermal stress and deformation generated during the solidification process of ingot and mould have been analyzed by two dimensional thermal elasto-plastic theories. Distributions of temperature, stress and relative displacement of the mould are calculated by the finite element method and compared with experimental results. In the elasto-plastic thermal stress analysis, compressive stress occurred at the inside wall of the mould whereas tensile stress occurred at outside wall. A coincidence between the analytical and experimental results is found to be fairly good, showing that the proposed analytical method is reliable.

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The Thermal Elasto-plastic Analysis Using Layered Shell Element (적층 쉘 요소를 이용한 용접 열탄소성 해석)

  • Song, H.C.;Yum, J.S.;Jang, C.D.
    • Journal of Power System Engineering
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    • v.9 no.4
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    • pp.220-224
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    • 2005
  • The thermal elasto-plastic analysis for the prediction of welding distortion of a 3 dimensional large-scaled ship structure is a very time-consuming work since the analysis is a nonlinear problem, and a lot of finite elements are needed to simulate the large ship hull block. Generally, 3-D finite elements have been used in the 3-D welding distortion problem to assess precisely the temperature gradient through the thickness direction of the welding plate. As a result of the adoption of 3-D element, degrees of freedom are rapidly increased in the problem to be solved. In this study, to improve the time efficiency of welding thermal elasto-plastic analysis, a layered shell element was proposed to simulate 3-D temperature gradient, and the results were compared with the experiment. The experiments were carried out for the type of bead-on-plate welding, and we found the measured data have a good agreement with the FEA results.

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