• Title/Summary/Keyword: Thermo elasto-plastic analysis

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Introduction of Barcelona Basic Model for Analysis of the Thermo-Elasto-Plastic Behavior of Unsaturated Soils (불포화토의 열·탄소성 거동 분석을 위한 Barcelona Basic Model 소개)

  • Lee, Changsoo;Yoon, Seok;Lee, Jaewon;Kim, Geon Young
    • Tunnel and Underground Space
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    • v.29 no.1
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    • pp.38-51
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    • 2019
  • Barcelona Basic Model (BBM) can describe not only swelling owing to decrease in effective stress, but also wetting-induced swelling due to decrease in suction. And the BBM can also consider increase in cohesion and apparent preconsolidation stress with suction, and decrease in the apparent preconsolidation stress with temperature. Therefore, the BBM is widely used all over the world to predict and to analyze coupled thermo-hydro-mechanical behavior of bentonite which is considered as buffer materials at the engineered barrier system in the high-level radioactive waste disposal system. However, the BBM is not well known in Korea, so this paper introduce the BBM to Korean rock engineers and geotechnical engineers. In this study, Modified Cam Clay (MCC) model is introduced before all, because the BBM was first developed as an extension of the MCC model to unsaturated soil conditions. Then, the thermo-elasto-plastic version of the BBM is described in detail.

An Analysis of Thermal Stress and Angular Distortion in Bead-on-Plate Welding Incorporating Constrained Boundary Conditions (판재의 비드 용접에서 구속경계조건을 적용한 열응력 및 각변형 해석)

  • 배강열;최태완
    • Journal of Welding and Joining
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    • v.17 no.1
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    • pp.104-115
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    • 1999
  • There have been many studies on the two dimensional thermo-elasto-plastic analysis in welding process, mostly from viewpoint of residual stresses. In this study, the temperature distribution, transient thermal stress, and angular distortion during bead-on-plate gas metal arc welding of rectangular plates were analyzed by using the finite element method. A nonlinear heat transfer analysis was first performed by taking account of the temperature-dependent material properties and convection heat losses on the surface. This was followed by a thermo-elasto-plastic stresses and distortion analysis that incorporates the constrained boundary condition of the two dimensional solution domain to get the three dimensional size effect of the plate. The constrained boundary conditions adopted in this study were the constant displacement condition over the whole two dimensional section for axial movement in the welding direction, and the force boundary condition for rotational movementof the domain around the axis of the welding direction. It could be revealed that the theoretical predictions of the angular distortion have an improved agreement with the experimentally obtained data presented in the previous study.

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An Analysis Finite Element for Elasto-Plastic Stresses Considerating Phase Transformation at the Quenching Process(II) -From Austenite to Martensite- (퀜칭과정에서 상변태를 고려한 탄소성 열응력의 유한요소 해석(II) -오오스테나이트에서 마르텐사이트로의 변태-)

  • Kim, O.S.;Song, G.H.;Koo, B.K.
    • Journal of the Korean Society for Heat Treatment
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    • v.8 no.1
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    • pp.12-23
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    • 1995
  • In this a set of constitutive equation relevant to the analysis of thermo-elasto-plastic materials with phase transformation during quenching process was presented on the basis of continuum thermo-dynamic. In calculating the transient thermal stresses, temperature between coolant and specimen(SM45C) surface was determined from the heat transfer coefficient. A calculation was made for specimen with 40mm in diameter quenched in coolant from $820^{\circ}C$ and the results are as follow. Stresses at starting point of transformation always show the maximum tensile value. Reverse of stresses takes place after completion of transformation of inner part at specimen.

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Finite Element Formulation for the Finite Strain Thermo-Elasto-Plastic Solid using Exponential Mapping Algorithm : Model and Time Integration Scheme (지수 사상을 이용한 비선형 열-탄소성 고체의 유한요소해석 : 모델과 시간적분법)

  • 박재균
    • Journal of the Earthquake Engineering Society of Korea
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    • v.8 no.2
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    • pp.19-25
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    • 2004
  • The linear analysis for the balance of linear momentum of a structure is relatively easy to perform, but the error becomes large when the structure experiences large deformation. Therefore, the material and geometric nonlinearity need to be considered for the precise calculations in that case. The plastic flow of a ductile steel-like metal mainly transforms its dissipated mechanical energy into heat, which transfers under the first and second law of thermodynamics. This heat increases the temperature of the material and the strength of the material decreases accordingly, which affects mechanical behavior of the given structure. This paper presents a finite-strain thermo-elasto-plastic steel model. This model can handle large deformation and thermal load simultaneously, which is common during earthquake periods. Two 3-dimensional finite element analyses verify this formulation.

The Analysis of Welding Deformation in Large Welded Structure by Using Local & Global Model (Local & Global 모델을 이용한 용접구조물 변형 해석에 관한 연구)

  • Jang Kyoung-Bok;Cho Si-Hoon;Jang Tae-Won
    • Journal of Welding and Joining
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    • v.22 no.6
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    • pp.25-29
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    • 2004
  • Some industrial steel structures are composed by components linked by several welding joints to constitute an assembly. The main interest of assembly simulation is to evaluate the global distortion of welded structure. The general method, thermo-elasto-plastic analysis, leads to excessive model size and computation time. In this study, a simplified method called "Local and Global approach" was developed to break down this limit and to provide a accurate solution for distortion. Local and global approach is composed of 3 steps; 1) Local simulation of each welding joint on a dedicated mesh (usually very fine due to high thermal gradients), taking into account for the non linearity of the material properties and the moving heat source. 2) Transfer to the global model of the effects of the welding joints by projection of the plastic strain tensors. 3) Elastic simulation to determine final distortions in global model. The welding deformation test for mock-up structure was performed to verify this approach. The predicted welding distortion by this approach had a good agreement with experiment results.

An Finite Element Analysis for Elasto-Plastic Thermal Stresses Considerating Strain Hysteresis at Quenching Process of Carbon Steel(II) - Analysis of elasto-viscoplastic thermal stress - (탄소강의 퀜칭처리 과정에서 변형율이력을 고려한 탄소성열응력의 유한요소 해석(II) - 탄점소성 열응력 해석 -)

  • Kim, Ok-Sam;Koo, Bon-Kwon
    • Journal of the Korean Society for Heat Treatment
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    • v.9 no.2
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    • pp.147-158
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    • 1996
  • Generally, analytical consideration on the behaviour of metallic structures during quenching process, and analysis on the thermal stress and deformation after heat treatment are very important in presumption of crack and distorsion of quenched material. In this study a set of constitute equations relevant to the analysis of thermo elasto-viscoplastic materials with strain hysteresis during quenching process way presented on the basis of contimuum thermo-dynamics mechanics. The thermal stresses were numerically calculated by finite element technique of weighted residual method and the principle of virtual work. In the calculation process, the temperature depandency of physical and mechaniclal properties of the material in consideration. On the distribution of elasto-viscoplastic thermal stresses according to radial direction, axial and tangential stress are tensile stress(50MPa, 1.5GPa and 300MPa) in surface and compressive stress(-1.2GPa, -1.14GPa and -750MPa) in the inner part on the other hand, radial stress is tensile stress(900MPa) in area of analysis. According to axial direction, tangential stress gradients are average 60MPa/mm on the whole. The reversion of stress takes place at 11.5 to 16.8mm from the center in area of analysing.

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Analysis of Welding Distortion during the Production of Fuel Tanks for Excavators (연료탱크 제작시 시뮬레이션을 통한 용접변형 해석)

  • Yang, Young-Soo;Kim, Duck-Youn;Bae, Kang-Yul
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.6
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    • pp.24-34
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    • 2016
  • To attach a fuel tank to an excavator, two sets of mounting plates on which three bosses are attached are welded onto the tank. In this study, the welding process of a fuel tank for an excavator was modeled using a finite element numerical method. The tank was modeled as a simple plate to which the mounting plate or bosses were attached by fillet welding. Thermal and thermo-elasto-plastic analyses of the welding process were carried out to predict the temperature distribution and material distortion during welding, respectively. Three different welding sequences for the tank were also modelled to compare the deformation that occurred due to each welding sequence. The results of the analysis predicted that changing the welding sequence around the mounting plate could not position the boss within the allowable dimensional range. The results also revealed the sequence in which the maximum distortion of the bosses welded onto the tank was 30% less than the maximum distortion due to the other sequences.

Development of Deformation Predicting Model for Line Heating of Steel Plates (강판의 선상가열시 변형량 예측모델의 개발)

  • Lim, Dong-Yong;Lee, Joo-Sung
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.10a
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    • pp.121-126
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    • 2003
  • This paper is concerns with the development of the formulae to predict deformation of curved plate due to line heating. For this purpose thermal elasto-plastic analysis has been carried out for both flat and curved plate models with varying parameters which affect the result of line heating. based on the results of numerical analysis, the formulae for predicting angular deformation has been derived through the regression analysis, which. It has been seen that the present model well agrees with the numerical analysis results and can reflect the curvature effect of plate to be heated. This paper ends with some comments on this formulae.

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Development of Deformation Predicting Model for Line Heating of Steel Plates (강판의 선상가열시 변형량 예측 모델의 개발)

  • Lim Dong-yong;Lee Joo-sung
    • Special Issue of the Society of Naval Architects of Korea
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    • 2005.06a
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    • pp.177-184
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    • 2005
  • This paper is concerns with the development of the formulae to predict deformation of curved plate due to line heating. For this purpose thermal elasto-plastic analysis has been carried out for both flat and curved plate models with varying parameters which affect the result of line heating. based on the results of numerical analysis, the formulae for predicting angular deformation has been derived through the regression analysis, which. It has been seen that the present model well agrees with the numerical analysis results and can reflect the curvature effect of plate to be heated. This paper ends with some comments on this formulae.

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The effect of corner shape in the casting mould on thermal stresses distribution (金型의 모서리부 形狀이 熱應力分布에 미치는 影響)

  • 민수홍;구본권;김옥삼
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.567-574
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    • 1991
  • In this study thermal stress generated in three ingot moulds(GC25) during the solidification process of aluminum were analyzed by the two-dimensional thermo-elasto-plastic theory. In temperature analysis, all of the three models are shown steep temperature rising each case in initial stage of cooling. In thermal stress analysis, all of three models took compressible stress on inside wall of the mould, and tensible along with on out side. Model 2 take place less compressible, tensible stress then model 1. But model 3. have similar as thermal stress as model 2. The analysis will made one possible to calculate an optimum mould shape whose thermal stress gradient becomes minimum.