• Title/Summary/Keyword: Elasto-Plastic Finite Element Method

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TAFEM을 이용한 터널 예제 해석

  • Jo, Seon-Gyu;Jeong, Jae-Dong;Eom, Jong-Uk
    • Proceedings of the Korean Geotechical Society Conference
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    • 1991.10a
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    • pp.216-232
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    • 1991
  • This Finite Element Program(TAFEM) has been developed to be able to carry out the structural analsis of tunnel section and simulate the surrounding ground behaviour due to New Austrian Tunnelling Method, of which main support is the surrounding ground, itself. The Elasto-plastic theory has been applied. The used finite elements are 8-noded isoparametric element(rock & shotcrete), 2 or 3-noded rod element(rock bolt) and infinite boundary element. The load incremental method and tangential stiffness method has been used. Associated flow rule was applied to plastic flow and yield criteria inclued not only Mohr-Coulomb but also Drucker-Prager. In this paper, Drucker-Prager yield criterion has been used. The relationship between plastic strain and stress is based on the incremental strain concept and stress-strain equation on the basis of the stress path of each gauss point has been adopted. It may be rational that rock is considered to be no-tension material, so that no-tension analysis has been adopted in accordance with the brittle fracture constitutive equation.

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Modelling the rheological behaviour of fresh concrete: An elasto-viscoplastic finite element approach

  • Chidiac, S.E.;Habibbeigi, F.
    • Computers and Concrete
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    • v.2 no.2
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    • pp.97-110
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    • 2005
  • Rheological behaviour of fresh concrete is an important factor in controlling concrete quality. It is recognized that the measurement of the slump is not a sufficient test method to adequately characterize the rheology of fresh concrete. To further understand the slump measurement and its relationship to the rheological properties, an elasto-viscoplastic, 2-D axisymmetric finite element (FE) model is developed. The FE model employs the Bingham material model to simulate the flow of a slump test. An experimental program is carried out using the Slump Rate Machine (SLRM_II) to evaluate the finite element simulation results. The simulated slump-versus-time curves are found to be in good agreement with the measured data. A sensitivity study is performed to evaluate the effects of yield stress, plastic viscosity and cone withdrawal rate on the measured flow curve using the FE model. The results demonstrate that the computed yield stress compares well with reported experimental data. The flow behaviour is shown to be influenced by the yield stress, plastic viscosity and the cone withdrawal rate. Further, it is found that the value of the apparent plastic viscosity is different from the true viscosity, with the difference depending on the cone withdrawal rate. It is also confirmed that the value of the final slump is most influenced by the yield stress.

The Elasto-Plastic Stress Analysis of Tube Expansion for Marine TEMA(Tubular Exchanger Manufactures Associations) Heat Exchangers (선박용 TEMA 열교환기의 전열관 확관시 탄소성 응력 해석)

  • Kim, Ok-Sam;Park, Jong-Dai
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.17 no.2
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    • pp.173-178
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    • 2011
  • Marine TEMA heat exchanger is the equipment to transfer the heat energy through both fluids that are enclosed separately by applying conduction and convection phenomena for a large vessels, Especially for heat exchanger working under the high temperature and high pressure, the expansion ratio should be taken into account other than under the low temperature and low pressure. This study was tried to find out the ideal expansion ratio through analyzing the elasto-plastic stress behavior of deformation while tubes are expanded with the finite element methods.

The Plane-Deformation Thermal Elasto-Plastic Analysis During Welding of Plate (평판용접에 관한 평면변형 열탄소성 해석)

  • 방한서;한길영
    • Journal of Ocean Engineering and Technology
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    • v.8 no.1
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    • pp.33-40
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    • 1994
  • Welding of structure produces welding residual stresses which influence buckling strength, brittle fracture strength and cold crack on the weld parts. Therefore, it is very important to accurately analyze the residual stress before welding in order to guarantee the safety of weldment. If the weld length is long enough compared to the thickness and the breadth of plate, thermal and mechanical behaviors in the middle portion of the plate are assumed to be uniform along the thickness direction(z-axis). Thus, the following conditions(so-called plane deformation) can be assumed for the plate except near its end;1) distributions of stress and strain are independent on the z-axis;2) plane normal to z-axis before deformation remains plane during and after deformation. In this paper, plane-deformation thermal elasto-plastic problem is formulated by being based on the finite element method. Moreover special regards and paid to the fact that material properties in elastic and plastic region are temperature-dependence. And the method to solve the plane-deformation thermal elasto-plastic problem is shown by using the incremental technique. From the results of analysis, the characterisics of distribution of welding residual stress and plastic strain with the production mechanism are clarified.

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Three Dimensional Finite Element Analysis for Powder Forging Process (분말단조 공정의 3차원 유한요소해석)

  • 김형섭
    • Journal of Powder Materials
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    • v.3 no.2
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    • pp.104-111
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    • 1996
  • In order to obtain homogeneous and high quality products in powder compaction forging process, it is very important to control stress, strain, density and density distributions. Therefore, it is necessary to understand quantitatively the elasto-plastic deformation and densification behaviors of porous metals and metal powders. In this study, elasto-plastic finite element method using Lee-Kim's pressure dependent porous material yield function has been used for the analysis of three dimensional indenting process. The analysis predicts deformed geometry, stress, strain and density distribution and load. The calculated load is in good agreement with experimental one. The calculated results do not show axisymmetric distributions because of the edge effect. The core part which is in contact with the indentor and the outer diagonal edge part are in compressive stress states and the middle part is in tensile stress state. As a results, it can be concluded that three dimensional analysis is more realistic than axisymmetric assumption approach.

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Reliability Analysis of Stochastic Finite Element Model by the Adaptive Importance Sampling Technique (적응적 중요표본추출법에 의한 확률유한요소모형의 신뢰성분석)

  • 김상효;나경웅
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 1999.10a
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    • pp.351-358
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    • 1999
  • The structural responses of underground structures are examined in probability by using the elasto-plastic stochastic finite element method in which the spatial distributions of material properties are assumed to be stochastic fields. In addition, the adaptive importance sampling method using the response surface technique is used to improve simulation efficiency. The method is found to provide appropriate information although the nonlinear Limit State involves a large number of basic random variables and the failure probability is small. The probability of plastic local failures around an excavated area is effectively evaluated and the reliability for the limit displacement of the ground is investigated. It is demonstrated that the adaptive importance sampling method can be very efficiently used to evaluate the reliability of a large scale stochastic finite element model, such as the underground structures located in the multi-layered ground.

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Finite Element Analysis of Gas Pipelines Depend on the Arctic of Active Region (극한지 활동층 변화에 따른 천연가스배관의 유한요소해석)

  • Yeom, Kyu Jung;Kim, Kyung Il;Kim, Young-Pyo;Oh, Kyu Hwan;Kim, Woo Sik
    • Journal of the Korean Institute of Gas
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    • v.18 no.5
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    • pp.72-77
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    • 2014
  • It is known that there is no demand for building the arctic environment in Korea. However, it is important to use the different energy source instead of fuel source due to global warming. It is now demanded of using gas of Alaska and Siberia for long term developing the natural gas. The design of gas pipelines in Korea is very different from the arctic region. The operation of gas in arctic region have to consider of arctic region such as permafrost and active regions. It is needed to understand of gas pipeline design with different arctic soil properties. Nowadays, the pipelines is designed with stress-based and but there is demanded for strain based design with more deformed pipeline. We study of arctic environment with different active region using Finite Element Method of thermal elasto-plastic analysis.

A Simplified Method to Predict the Weld-induced Deformation of Curved Plates (곡판의 용접변형 예측을 위한 간이 해석법)

  • Lee, Joo-Sung;Hoi, Nguyen Tan
    • Journal of the Society of Naval Architects of Korea
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    • v.44 no.5
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    • pp.474-481
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    • 2007
  • A three-dimensional finite element model has been used to simulate the bead on plate welding of curved steel plates having curvature in the welding direction. By using traditional method such as thermal-elastic-plastic(TEP) finite element analysis. the weld-induced deformation can be accurately predicted. However, three-dimensional finite element analysis is not practical in analyzing the weld-induced deformation of large and complex structures such as ship structures in view of computing time and cost. In this study, used is the equivalent loading method based on inherent strain to illustrate the effect of the longitudinal curvature upon the weld-induced deformation of curved plates.

A Study on the Yield Criterion of Metal Powders (금속 분말의 항복조건에 관한 연구)

  • 박성준;한흥남;오규환;이동녕
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 1996.10a
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    • pp.131-138
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    • 1996
  • A new yield criterion for metal powder compaction based on continuum mechanics has been proposed. It includes three parameters to characterize the geometrical hardening of powder compact and strain hardening of incompressible metal matrix. The elasto-plastic finite element method to describe compaction of metal powders has been formulated using the new yield criterion. The values of parameters in the yield criterion can be determined using cold isostatic pressing(CIP). The finite element method can simulate compaction behavior of various copper powders.

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A finite element yield line model for the analysis of reinforced concrete plates

  • Rasmussen, L.J.;Baker, G.
    • Structural Engineering and Mechanics
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    • v.6 no.4
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    • pp.395-409
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    • 1998
  • This paper concerns the development and implementation of an orthotropic, stress resultant elasto-plastic finite element model for the collapse load analysis of reinforced concrete plates. The model implements yield line plasticity theory for reinforced concrete. The behaviour of the yield functions are studied, and modifications introduced to ensure a robust finite element model of cases involving bending and twisting stress resultants ($M_x$, $M_y$, $M_{xy}$). Onset of plasticity is always governed by the general yield-line-model (YLM), but in some cases a switch to the stress resultant form of the von Mises function is used to ensure the proper evolution of plastic strains. Case studies are presented, involving isotropic and orthotropic plates, to assess the behaviour of the yield line approach. The YLM function is shown to perform extremely well, in predicting both the collapse loads and failure mechanisms.