• 제목/요약/키워드: Thermo-viscoplastic Finite Element Analysis

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공구끝단반경이 고려된 2차원 금속절삭에 대한 열-점소성 유한요소해석 (Thermo-viscoplastic finite element analysis of orthogonal metal cutting considered tool edge radius)

  • 김국원;이우영;신효철
    • 대한기계학회논문집A
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    • 제22권1호
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    • pp.1-15
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    • 1998
  • In this paper, thermo-viscoplastic finite element analysis of the effect of tool edge radius on cutting process are performed. The thermo-viscoplastic cutting model is capable of dealing with free chip geometry and chip-tool contact length. The coupling with thermal effects is also considered. Orthogonal cutting experiments are performed for 0.2% carbon steel with tools having 3 different edge radii and the tool forces are measured. The experimental results are discussed in comparison with the results of the FEM analysis. From the study, we confirm that this cutting model can well be applied to the cutting process considered the tool edge radius and that a major causes of the "size effect" is the tool edge radius. With numerical analysis, the effects of the tool edge radius on the stress distributions in workpiece, the temperature distributions in workpiece and tool, and the chip shape are investigated.estigated.

열유동을 고려한 SMC 압축성형공정의 3차원 유한요소 해석 (Coupled Thermo-Viscoplastic Three Dimensional Finite Element Anaysis of Compression Molding of Sheet Molding Compound)

  • 김수영;임용택
    • 대한기계학회논문집A
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    • 제20권2호
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    • pp.488-499
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    • 1996
  • SMC(Sheet molding compound) is a thermosetting material reinforced with chopped fiberglass. The compression molding of SMC was analyzed based on a rigid thermo-viscoplastic approach using a three dimensional finite element program coupled with temperatures. Only the temperature analysis part was tested in this paper by solving one-dimensional heat transfer problem and comparing with the exact solutions available in the literature. Based on this comparison the program was proved to be valid and was further applied in solving compression molding of SMC between flat dies. To investigate the usefulness of a rigid thermo-viscoplastic approach in the compression molding analysis of SMC charge, compression of rectangular shaped SMC charge at plane strain and three dimensionalde formation condition was analyzed under the same condition as given in the literature. From this comparison it was found out that the rigid thermo-viscoplastic approach was useful in analyzing SMC compression molding between flat dies.

A THERMO-ELASTO-VISCOPLASTIC MODEL FOR COMPOSITE MATERIALS AND ITS FINITE ELEMENT ANALYSIS

  • Shin, Eui-Sup
    • Journal of Theoretical and Applied Mechanics
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    • 제3권1호
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    • pp.45-65
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    • 2002
  • A constitutive model on oorthotropic thermo-elasto-viscoplasticity for fiber-reinforced composite materials Is illustrated, and their thermomechanical responses are predicted with the fully-coupled finite element formulation. The unmixing-mixing scheme can be adopted with the multipartite matrix method as the constitutive model. Basic assumptions based upon the composite micromechanics are postulated, and the strain components of thermal expansion due to temperature change are included In the formulation. Also. more than two sets of mechanical variables, which represent the deformation states of multipartite matrix can be introduced arbitrarily. In particular, the unmixing-mixing scheme can be used with any well-known isotropic viscoplastic theory of the matrix material. The scheme unnecessitates the complex processes for developing an orthotropic viscoplastic theory. The governing equations based on fully-coupled thermomechanics are derived with constitutive arrangement by the unmixing-mixing concept. By considering some auxiliary conditions, the Initial-boundary value problem Is completely set up. As a tool of numerical analyses, the finite element method Is used with isoparametric Interpolation fer the displacement and the temperature fields. The equation of mutton and the energy conservation equation are spatially discretized, and then the time marching techniques such as the Newmark method and the Crank-Nicolson technique are applied. To solve the ultimate nonlinear simultaneous equations, a successive iteration algorithm is constructed with subincrementing technique. As a numerical study, a series of analyses are performed with the main focus on the thermomechanical coupling effect in composite materials. The progress of viscoplastic deformation, the stress-strain relation, and the temperature History are careful1y examined when composite laminates are subjected to repeated cyclic loading.

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원추형금형을 통한 비 등온 열간 콘테이너 압출의 비정상상태 유한요소해석 (Non-steady state finite element analysis of nonisothermal hot container extrusion through conical dies)

  • 강연식;양동열
    • 한국정밀공학회지
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    • 제10권2호
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    • pp.30-39
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    • 1993
  • The study is concerned with the thermo-viscoplastic finite element analysis of nonisothermal hot container extrusion through conical dies. The problem is treated as a non-steady state incorporating the nonisothermal heat transfer analysis. The analysis of temperature distribution includes heat transfer though the boundary surface including conduction, convection and radiation. The analysis of heat transfer is decoupled with the analysis of deformation and the material interaction is considered through iteration procedure. The effect of important process parameters including die angle and extrusion ratio in the process is investigated. Due to the geometric feature for the container extrusion through conical dies, automatic remeshing is mandatory. Automatic remeshing is achieved by introducing the modular remeshing technique.

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AN ANALYSIS OF MOLDING AND CURING OF SMC BY THE FINITE ELEMENT METHOD

  • Kim, Naksoo-
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 1992년도 춘계학술대회 논문집 92
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    • pp.177-200
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    • 1992
  • A thermo-viscoplastic finite element program was developed to analyze the compression molding of SMC process. Deformation of the material was modelled by using the flow-rule. Heat balance during the process was coupled to the deformation. In the cure study, a kinetic model was adopted to describe the cure behavior. The numerical kinetic model was integrated with the thermo-viscoplastic numerical analysis by adding heat generation due to the chemical reaction of the workpiece in the heat transfer analysis. The integrated finite element program can simulate a whole sequential molding process including deformation, heat transfer, and chemical reaction. A practical SMC molding process with T-shaped substructure was simulated. The simulated results showed good agreements with experiments.

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반도체 패키지의 열변형 해석 시 유한요소 모델의 영향 (The Effect of Finite Element Models in Thermal Analysis of Electronic Packages)

  • 최남진;주진원
    • 대한기계학회논문집A
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    • 제33권4호
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    • pp.380-387
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    • 2009
  • The reliability concerns of solder interconnections in flip chip PBGA packages are produced mainly by the mismatch of coefficient of thermal expansion(CTE) between the module and PCB. Finite element analysis has been employed extensively to simulate thermal loading for solder joint reliability and deformation of packages in electronic packages. The objective of this paper is to study the thermo-mechanical behavior of FC-PBGA package assemblies subjected to temperature change, with an emphasis on the effect of the finite element model, material models and temperature conditions. Numerical results are compared with the experimental results by using $moir{\acute{e}}$ interferometry. Result shows that the bending displacements of the chip calculated by the finite element analysis with viscoplastic material model is in good agreement with those by $moir{\acute{e}}$ inteferometry.

평금형을 이용한 축대칭 열간 압출의 유한요소해석 (Finite Element Analysis of Axisymmetric Hot Extrusion Through Square Dies)

  • 강연식;박치용;양동열
    • 대한기계학회논문집
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    • 제16권2호
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    • pp.207-225
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    • 1992
  • The study is concerned with the thermo-viscoplastic finite element analysis of axisymmetric forward hot extrusion through square dies. The problem is treated as a nonsteady state problem because the distribution of temperature and material properties are continuously changing with the punch travel. In square die extrusion, difficulties arise from the severe distortion and die interference of elements at the aperture rim of the die even with a small punch travel. And finite element computation is impossible without intermittent remeshing. Accordingly, an automatic remeshing technique is proposed by employing specially designed mesh structure near the aperture rim. The analysis of temperature distribution includes heat conduction through material interfaces, heat convection and radiation to the atmosphere and is carried out by decoupling the heat analysis from the analysis of the deformation. The extrusion load and the distributions of strain rate and temperature are computed for the given cases rendering reasonable results. Computed grid distortions are found to be in good agreement with the experimental results. It has been thus shown that the proposed method of analysis can be effectively applied to the axisymmetric hot extrusion through square dies.

탄소강의 퀜칭처리 과정에서 변형율이력을 고려한 탄소성열응력의 유한요소 해석(II) - 탄점소성 열응력 해석 - (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 -)

  • 김옥삼;구본권
    • 열처리공학회지
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    • 제9권2호
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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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6061 알루미늄합금 휠 단조공정의 해석 (An Analysis on the Forging Processes for 6061 Aluminum Alloy Wheel)

  • 김영훈;유태곤;황병복
    • 소성∙가공
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    • 제8권5호
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    • pp.498-506
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    • 1999
  • The metal forming processes of aluminum alloy wheel forging at elevated temperature are analyzed by the finite element method. A coupled thermo-mechanical model for analysis of plastic deformation and geat transfer is adapted in the finite element formulation. In order to consider the strain-rate effects on material properties and the flow stress dependence on temperatures, rigid-viscoplasticity is introduced in this formation. In this paper, several process conditions were applied to the dimulation such as die speed, rib thickness, and depth of die cavity. Simulation results are compared, and discussed with each case. Metal flow, die pressure distributions, temperature distributions, velocity fields and forging loads are summarized as basic data for process design and selection of a proper press equipment.

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