• 제목/요약/키워드: Elasto-plastic Condition

검색결과 98건 처리시간 0.022초

유한요소법을 이용한 다공성금속의 고온변형해석 (Analysis of the Hot Deformation of Porous metals by Finite Element Method)

  • 한흥남;이용기;오규환;이동녕
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1994년도 추계학술대회 논문집
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    • pp.149-156
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    • 1994
  • The thermomechanical elasto-plastic problems in hot forging of the porous metals are analyzed using the thermo-elasto-plastic finite element method. This finite element program has been formulated using the yield condition advanced by Lee and Kim and developed using the thermo-elasto-plastic time integration procedure. Thermomechanical responses and densification behaviors of the porous metals during hot forging are calcucated at various initial relative densities, strain rates and temperatures. The calculated results are in good agreement with experimental data.

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케로신-공기 혼합물의 비정상연소 모델과 탄소성 관의 동적 거동 수치해석 (Numerical Analysis of Responses of a Elasto-plastic Tube under Kerosene-air Mixture Detonation)

  • 이영헌;곽민철;여재익
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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    • pp.169-172
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    • 2015
  • This paper presents a numerical investigation on kerosene-air mixture detonation and behaviors of thermal elasto-plstic thin metal tube under detonation loading based on multi-material analysis. The detonation loading is modeled by the kerosene-air mixture detonation which is compared with CJ condition and experimental cell size. And the thermal softening effect on elasto-plstic model of metal tube is indicated by different dynamic response of detonation loaded tube in various temperature and tube thickness.

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전기 업셋팅 가공시의 열탄소성 해석에 관한 연구 (A Study on the Thermo-elasto-plastic Analysis of Upset Forming)

  • 왕지석;박태인
    • Journal of Advanced Marine Engineering and Technology
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    • 제18권4호
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    • pp.69-76
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    • 1994
  • Thermal elasto-plastic analysis of axi-symmetric body by the finite element method is presented in this paper for analyzing the process of upset forming of circular section extruded bar. The example of calculation for upset forming of Nimonic extruded bar is also presented. It is shown that remeshing of quadrilateral finite element is necessary because the very highly distorted element by plastic deformation disturbs the calculation. Calculated values for nodal points in new mesh are obtained from nodal points of old mesh by linear interpolation method. The experimental results are compared with calculated values. The appearance of upsetupset forming obtained by experimental method is very similar to that obtained by calculations. So, it is proved that the thermal elasto-plastic analysis of axi-symmetric body by the finite element method is very useful for finding the optimum upsetting condition.

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일반화된 Hoek-Brown 파괴조건식의 강도정수 a와 터널 보강깊이가 원형터널의 탄소성 거동에 미치는 영향 (Effect of Strength Parameter a in the Generalized Hoek-Brown Failure Criterion and the Reinforcement Thickness on the Elasto-plastic Behavior of Circular Tunnel)

  • 이연규;박경순
    • 화약ㆍ발파
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    • 제26권2호
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    • pp.20-28
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    • 2008
  • 터널설계 시 내공변위 예측은 흔히 탄소성 해석을 통하여 수행되므로, 탄소성 해석법은 많은 연구자들의 관심을 끌고 있는 연구 주제이다. 그러나 일반화된 Hoek-Broun 암반에 굴착된 원형터널의 탄소성 거동은 그 중요성에도 불구하고 아직까지 연구가 미진한 실정이다. 이 연구에서는 Lee & Pietruszczak (2008)의 연구를 응용하여 주변이 환형으로 보강된 원형터널의 탄소성 해석을 위한 간단한 수치 해석법을 제안하였다. 터널은 일반화된 Hoek-Brown 파괴조건을 따르는 변형률연화 암반에 굴착되는 것으로 가정하였다. 제안된 방법의 검증을 위해 상업코드인 FLAC이 이용되었다. 예제 해석을 통해 Hoek-Brown 강도정수 a와 보강대의 두께가 터널 주변의 탄소성 거동에 미치는 영향을 검토하였다. 해석결과 이 두 변수가 터널주변의 응력 및 변위 분포에 미치는 영향은 상당히 큰 것으로 나타났다.

대형 용접구조물의 탄소성 열변형 해석을 위한 용접부의 변형률 경계조건에 관한 연구 (A Study on Weldment Boundary Condition for Elasto-Plastic Thermal Distortion Analysis of Large Welded Structures)

  • 하윤석
    • Journal of Welding and Joining
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    • 제29권4호
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    • pp.48-53
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    • 2011
  • A thermal distortion analysis which takes strains directly as boundary conditions removed barrier of analysis time for the evaluation of welding distortion in a large shell structure like ship block. If the FE analysis time is dramatically reduced, the structure modeling time or the input-value calculating time will become a new issue. On the contrary to this, if the calculation time of analysis input-value is dramatically reduced and its results also are more meaningful, a little longer analysis time could be affirmative. In this study, instead of using inherent strain based on elastic analysis, a thermal strain based on elasto-plastic analysis is used as the boundary condition of weldments in order to evaluate the welding distortion. Here, the thermal strain at the weldment was established by using a stress-strain curve established from the test results. It is possible to automatically recognize the modeling induced-stiffness in the shrinkage direction of welded or heated region. The validity of elasto-plastic thermal distortion analysis was verified through the experiment results with various welding sequence.

FINITE ELEMENT ANALYSIS AND MEASUREMENT ON THE RELEASE OF RESIDUAL STRESS AND NON-LINEAR BEHAVIOR IN WELDMENT BY MECHANICAL LOADING(I) -FINITE ELEMENT ANALYSIS-

  • Jang, Kyoung-Bok;Kim, Jung-Hyun;Cho, Sang-Myoung
    • 대한용접접합학회:학술대회논문집
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    • 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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    • pp.378-383
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    • 2002
  • In previous study, the decrease and recovery of total stiffness in welded structure was discussed on the basis of experimental examination through tensile loading and unloading test of welded specimen. The recovery of structure stiffness was caused by the release of welding residual stress through mechanical loading. In this study, analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result. Thermal elasto-plastic analysis for welding process was performed by non-coupled analysis. Analysis results of welding process were transfer to elasto-plastic model for tensile loading & unloading by restart technique. In elasto-plastic analysis model for mechanical loading & unloading, hardening appearance of weld metal was considered by rezoning technique and tying technique was used for JIG condition of test machine.

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Finite Element Analysis and Measurement on the Release of Residual Stress and Non-linear Behavior in Weldment by Mechanical Loading(I) -Finite Element Analysis-

  • Jang, K.B.;Kim, J.H.;Cho, S.M.
    • International Journal of Korean Welding Society
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    • 제2권1호
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    • pp.29-32
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    • 2002
  • In previous study, the decrease and recovery of total stiffness in welded structure was discussed on the basis of experimental examination through tensile loading and unloading test of welded specimen. The recovery of structure stiffness was caused by the release of welding residual stress through mechanical loading. In this study, analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result. Thermal elasto-plastic analysis for welding process was performed by non- coupled analysis. Analysis results of welding process were transfer to elasto-plastic model for tensile loading & unloading by restart technique. In elasto-plastic analysis model for mechanical loading & unloading, hardening appearance of weld metal was considered by rezoning technique and tying technique was used for JIG condition of test machine.

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GSI 지수의 변형률 연화를 고려한 원형터널의 탄소성 해석 (Elasto-plastic Analysis of Circular Tunnel with Consideration of Strain-softening of GSI Index)

  • 이연규;박경순
    • 터널과지하공간
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    • 제20권1호
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    • pp.49-57
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    • 2010
  • 이 연구에서는 정수압 지압 조건의 암반에 굴착되는 원형 터널의 탄소성 거동 해석을 위해 GSI 지수의 변형률연화를 고려한 탄소성 해석법이 제안되었고, 그 적용성이 검토되었다. 제안된 수치해석법은 Lee & Pietruszczak(2008)의 탄소성 해석방법을 수정하여 개발되었다. 터널 주변 암반에서는 발파와 굴착에 의한 암반의 손상으로 GSI 지수의 저하가 야기될 수 있다는 가정 하에 GSI 지수의 변형률연화 개념을 도입하였다. 일반화된 Hoek-Brown 식의 강도정수들은 GSI 값을 이용하여 경험적으로 계산할 수 있으므로 GSI 지수의 변형률연화 개념을 도입함으로써 이 강도정수들의 변형률연화가 해석에 반영되도록 하였다. 제안된 방법의 적합성을 검토하기위하여 여러 해석조건에서 원형터널의 탄소성 해를 구하고 그 결과를 고찰하였다.

강체요소법에 의한 구형쉘의 탄소성해석에 관한 면구(II) -개구부 링을 갖는 구형쉘의 탄성 및 탄소성 해석- (A STUDY ON ELASTO-PLASTIC ANALYSIS OF SPHERICAL SHELL BY RIGID ELEMENT METHOD(II) - Elasto-Plastic Analysis of Spherical Shell with Open Stiff Ring -)

  • 박강근;서삼열;한상율;권택진
    • 한국전산구조공학회:학술대회논문집
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    • 한국전산구조공학회 1988년도 가을 학술발표회 논문집
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    • pp.24-29
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    • 1988
  • In this paper, it is proposed hew the rigid element method suggested in the first paper can be applied to the elastic and elasto-plastic analysis of spherical shell with the open stiff ring. In the analytical model, the solution domain is divided into rectangular-shaped spherical bending elements. Each contact surface of two adjacent elements is interconnected with four elastic springs, and it is assumed that the internal forces are distritributed into springs. The 6 degrees of freedom of the element are placed in the center of elements, and the 6 cen-teroidal rigid displacements affect other elements through springs around elements. And then the solution domain is estimated by the behavior of elements and springs. In this study, these concepts are applied to the elastic and elasto-plastic analysis for the eight cases of the spherical shell according to the condition of stiff ring, the condion of loading and the size of opening. And then some numerical results such as the distribution of stresses, the force-displacement curves and the mode of fractures will he shown.

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외연적 탄소성 유한요소해석에서의 민감도 해석과 준정적 변형에의 응용 (Sensitivity Analysis of the Explicit Elasto-plastic Finite Element Method and Application to the Quasi-static Deformation)

  • 김세호;허훈
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 춘계학술대회논문집C
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    • pp.402-407
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    • 2001
  • Sensitivity analysis scheme is developed in the elasto-plastic finite element method with explicit time integration using direct differentiation method. The direct differentiation is concerned with the time integration, constitutive relation, shell element with reduced integration and the contact scheme. Sensitivity analysis results are mainly examined with the highly nonlinear and quasi-static problem with the complicated contact condition. The result shows stable sensitivity especially in the sheet metal forming analysis.

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