• Title/Summary/Keyword: Elasto-plastic Condition

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

  • 한흥남;이용기;오규환;이동녕
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1994.10a
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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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Numerical Analysis of Responses of a Elasto-plastic Tube under Kerosene-air Mixture Detonation (케로신-공기 혼합물의 비정상연소 모델과 탄소성 관의 동적 거동 수치해석)

  • Lee, Younghun;Gwak, Min-cheol;Yoh, Jai-ick
    • 한국연소학회:학술대회논문집
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    • 2015.12a
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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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A Study on the Thermo-elasto-plastic Analysis of Upset Forming (전기 업셋팅 가공시의 열탄소성 해석에 관한 연구)

  • 왕지석;박태인
    • Journal of Advanced Marine Engineering and Technology
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    • v.18 no.4
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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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Effect of Strength Parameter a in the Generalized Hoek-Brown Failure Criterion and the Reinforcement Thickness on the Elasto-plastic Behavior of Circular Tunnel (일반화된 Hoek-Brown 파괴조건식의 강도정수 a와 터널 보강깊이가 원형터널의 탄소성 거동에 미치는 영향)

  • Lee, Youn-Kyou;Park, Kyung-Soon
    • Explosives and Blasting
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    • v.26 no.2
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    • pp.20-28
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    • 2008
  • In the design stage of a tunnel, the wall convergence is commonly estimated through an elasto-plastic analysis of the tunnel, which has been a topic drawing many researcher's attention so far. Despite its importance, however, the elasto-plastic behavior of a circular tunnel excavated in a generalized Hoek-Brown rockmass is still poorly understood. In this study, a simple munerical method based on Lee & Pietruszczak (2008) for the elasto-plastic analysis of a circular tunnel surrounded by reinforced annulus is proposed. It is assumed that the tunnel is excavated in a strain-softening rockmass obeying the generalized Hoek-Brown failure condition. The commercial code FLAC is used for the verification of the proposed method. The influence of the Hoek-Brown strength parameter a and the thickness of the reinforcement annulus on the elasto-plastic behavior around the tunnel was discussed by conducting some example analyses. The results show that the influence of these two parameters on the distribution of stresses and displacements is substantial.

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

  • Ha, Yun-Sok
    • Journal of Welding and Joining
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    • v.29 no.4
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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
    • Proceedings of the KWS Conference
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    • 2002.10a
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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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    • v.2 no.1
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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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Elasto-plastic Analysis of Circular Tunnel with Consideration of Strain-softening of GSI Index (GSI 지수의 변형률 연화를 고려한 원형터널의 탄소성 해석)

  • Lee, Youn-Kyou;Park, Kyung-Soon
    • Tunnel and Underground Space
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    • v.20 no.1
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    • pp.49-57
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    • 2010
  • For the elasto-plastic analysis of a circular tunnel driven in a strain-softening rock mass subjected to a hydrostatic in-situ stress condition, this study suggests a convenient elasto-plastic analysis scheme which takes the strain-softening of GSI index into account and demonstrates its potential as a numerical tool in designing a circular tunnel. The suggested numerical scheme was developed by modifying the previous elasto-plastic procedure proposed by Lee & Pietruszczak(2008). With the assumption that GSI index of rock mass adjacent to the tunnel surface may be degraded due to the damage caused by the blasting and excavation, the concept of the strain-softening of GSI index was invoked. The concept provides a useful tool considering the strain-softening of the strength parameters appearing in the generalized Hoek-Brown criterion because these parameters can be evaluated empirically by use of GSI. In order to check the validity of the proposed scheme, the elasto-plastic analyses for circular tunnels were performed in various analysis conditions and the results were discussed.

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

  • 박강근;서삼열;한상율;권택진
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1988.10a
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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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Sensitivity Analysis of the Explicit Elasto-plastic Finite Element Method and Application to the Quasi-static Deformation (외연적 탄소성 유한요소해석에서의 민감도 해석과 준정적 변형에의 응용)

  • Kim, Se-Ho;Huh, Hoon
    • Proceedings of the KSME Conference
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    • 2001.06c
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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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