• Title/Summary/Keyword: Heat element

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Analysis of Welding Residual Stresses and Heat Treatment used by Finete Element Method (유한요소법을 이용한 용접 잔류응력과 열처리 해석)

  • Lee, Bong-Yeol;Jo, Jong-Rae;Mun, Yeong-Hun
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.334-339
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    • 2003
  • The welding residual stress has on important effect on welding deformation, fatigue fracture, buckling strength, brittle fracture, etc. For the purpose of relaxation of welding residual stress, post welding heat treatment is widely used. In this paper, residual stresses were calculated by two dimensional thermal elasto-plastic analysis using finite element method. Heat transfer analysis are performed by transient analysis. Also structure analysis are carried out by of thermal-mechanical coupled analysis. Numerical analysis are used by ANSYS 5.7.

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Cure and Heat Transfer Analysis in LED Silicone Lens using a Dynamic Cure Kinetics Method (승온 반응속도식을 이용한 LED용 실리콘 렌즈의 경화 및 열전달해석)

  • Song, M.J.;Kim, K.H.;Hong, S.K.;Park, J.Y.;Lee, J.W.;Yoon, G. S.
    • Transactions of Materials Processing
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    • v.24 no.2
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    • pp.101-106
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    • 2015
  • Recently, silicone is being used for LED chip lens due to its good thermal stability and optical transmittance. In order to predict residual stresses, which cause optical birefringence and mechanical warpage of silicone, a finite element analysis was conducted for the curing of silicone during molding. For the analysis of the curing process, a dynamic cure kinetics model was derived based on the results of a differential scanning calorimetry (DSC) testing and applied to the material properties for finite element analysis. Finite element simulation results showed that a step cure cycle reduced abrupt reaction heat and showed a decrease in the residual stresses.

Stochastic finite element method homogenization of heat conduction problem in fiber composites

  • Kaminski, Marcin
    • Structural Engineering and Mechanics
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    • v.11 no.4
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    • pp.373-392
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    • 2001
  • The main idea behind the paper is to present two alternative methods of homogenization of the heat conduction problem in composite materials, where the heat conductivity coefficients are assumed to be random variables. These two methods are the Monte-Carlo simulation (MCS) technique and the second order perturbation second probabilistic moment method, with its computational implementation known as the Stochastic Finite Element Method (SFEM). From the mathematical point of view, the deterministic homogenization method, being extended to probabilistic spaces, is based on the effective modules approach. Numerical results obtained in the paper allow to compare MCS against the SFEM and, on the other hand, to verify the sensitivity of effective heat conductivity probabilistic moments to the reinforcement ratio. These computational studies are provided in the range of up to fourth order probabilistic moments of effective conductivity coefficient and compared with probabilistic characteristics of the Voigt-Reuss bounds.

Efficient Finite Element Heat Transfer Analysis by Decomposing a Domain and Radiation Boundaries (영역 및 복사 경계의 완전 분할을 통한 유한요소 열전달 해석의 효율화)

  • Shin, Eui-Sup;Kim, Yong-Uhn;Kim, Sung-Jun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.10
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    • pp.836-843
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    • 2008
  • An efficient domain/boundary decomposition method is applied for heat transfer problems with non-linear thermal radiation boundaries. The whole domain of solids or structures is considered as set of subdomains, an interface, and radiation interfaces. In a variational formulation, simple penalty functions are introduced to connect an interface or radiation interfaces with neighboring subdomains that satisfy continuity conditions. As a result, non-linear finite element computations due to the thermal radiation boundaries can be localized within a few subdomains or radiation interfaces. Therefore, by setting up suitable solution algorithms for the governing finite element equations, the computational efficiency can be improved considerably. Through a set of numerical examples, these distinguishing characteristics of the present method are investigated in detail.

Computation of Stress Field During Additive Manufacturing by Explicit Finite Element Method (외연적 유한요소법을 이용한 적층제조 공정 중 응력 장 변화 계산)

  • Yang, Seung-Yong;Kim, Jeoung Han
    • Journal of Powder Materials
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    • v.27 no.4
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    • pp.318-324
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    • 2020
  • In the present work, an explicit finite element analysis technique is introduced to analyze the thermal stress fields present in the additive manufacturing process. To this purpose, a finite element matrix formulation is derived from the equations of motion and continuity. The developed code, NET3D, is then applied to various sample problems including thermal stress development. The application of heat to an inclusion from an external source establishes an initial temperature from which heat flows to the surrounding body in the sample problems. The development of thermal stress due to the mismatch between the thermal strains is analyzed. As mass scaling can be used to shorten the computation time of explicit analysis, a mass scaling of 108 is employed here, which yields almost identical results to the quasi-static results.

Effects of Heat Input and Bead Generation Methods on Finite Element Analysis of Cylindrical Multi-Pass Welding Process of Metals (열원 입력과 비드 생성 방법이 원통형 다층 금속 용접 과정의 유한요소해석에 미치는 영향)

  • Park, Won Dong;Bahn, Chi Bum;Kim, Ji Hoon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.41 no.6
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    • pp.455-467
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    • 2017
  • In this study, a finite element analysis of a cylindrical multi-pass weldment for dissimilar metals was performed. The effects of the heat input method and weld bead generation method were considered. We compared two heat input methods: the heat flux method and the temperature method. We also compared two weld bead generation methods: the element birth method and the quiet element method. Although the results of the thermal analysis show deviations between the two heat input methods, the welding residual stresses were similar. Because the areas exposed to high temperature were similar and the strength of the material was very low in high temperature (above the $1000^{\circ}C$), the effects of the weld bead temperature were insignificant. The distributions of the welding residual stress were similar to each other. However, gaps and overlaps occurred on the welding boundary surfaces when the element birth method was applied. The quiet element method is more suitable for a large deformation model in order to simulate a more accurate weld shape.

A Study on the 3-D Unsteady State Heat Transfer Coupled by Conductive Currents (전기장 변화에 따른 3차원 비정상 상태 열전달 연계 해석에 관한 연구)

  • Kwac, L.K.;Kim, H.G.
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.1
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    • pp.29-34
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    • 2008
  • A modeling technique for the 2-way coupling of heat transfer and conduction currents has been performed to inspire a combined analytical simulation. The 3-D finite element method is used to solve steady conduction currents and heat generation in an aluminum film deposited on a silicon substrate. The model investigates the temperature in the device after the current is applied. The conservation equation of energy, the Maxwell equations for conduction currents, the unsteady state heat transfer equation and the Fourier's law for heat transfer are implemented as a bidirectionally coupled problem. It is found that the strongly coupled temperature and time dependent heat equations give a reasonable results and an explicit solving technique.

Simulation of Heat Supply Control of Continuous Heating System of Multistoried Apartment in Consideration of Radiation Heat Transfer (복사열전달을 고려한 고층아파트 연속난방 열공급제어 시뮬레이션)

  • Choi, Y.D.;Hong, J.K.;Yoon, J.H.;Lee, N.H.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.6 no.2
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    • pp.78-92
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    • 1994
  • Thermal performance of pipe network of continuous heating system controlled by thermostat and flow control valve was simulated in consideration of radiation heat transfer and solved by linear analysis method. Thermal performance of real apartment building with radiant floor heating system was simulated by equivalence heat resistance-capacity method. This method enables to simulate the unsteady variation of temperature or each element of building. Heat transfer characteristics of each element were also investigated.

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Manufacturing Process Design of High Strength Al 6056 Bolts by Strain Hardening Effect (가공경화를 이용한 고강도 Al 6056 볼트의 생산 공정설계)

  • Park, J.S.;Kim, Y.B.;Kim, S.W.;Kim, H.S.;Ann, K.H.;Park, J.S.;Kang, J.H.
    • Transactions of Materials Processing
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    • v.30 no.4
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    • pp.165-171
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    • 2021
  • This study was conducted on the manufacturing method of high-strength aluminum bolts. We obtained the displacement-load information by tensile test of the Al 6056 raw material and the T6 heat-treated material and calculated the precise flow stress and fracture limit using repetitive finite element analysis for before and after heat treatment. We designed a multi-stage forging process for T6 heat-treated material, and calculated that the accumulated damage value does not exceed fracture limits by finite element method. We produced the prototype forgings without any harmful defects such as cracks and folding occurring. Bolts made of T6 heat treated material show 9.6%higher tensile strength than T6 heat treated material after wire drawing.

Image Processing Technology for Analyzing the Heating State of Carbon Fiber Surface Heating Element (탄소섬유 면상발열체의 발열 상태 분석을 위한 영상처리 기술)

  • Cho, Joon-Ho;Hwang, Hyung-Soo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.19 no.2
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    • pp.683-688
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    • 2018
  • In this study, we analyzed the heat generation state of a flat heating element by using image processing technology in conjunction with carbon fiber. The flat heating element is manufactured by chopping the carbon fiber to a small size and bonding it again using a dispersing agent. The solution of carbon fiber, bound together using the dispersant, is then filtered onto the nonwoven fabric. The last step is to obtain flat carbon fibers in the form of nonwoven fabrics for the purpose of drying the filtered carbon fibers. In the flat heating element, electricity may be applied to the carbon fiber on the surface produced in this manner. In this study, the flat heating element was analyzed by four methods. The analysis of the heat generation characteristics and heating rate of the flat heating element confirmed that the fabricated sheet heating element corresponds to a normal army. The analysis of the insulation coating and flat heating element module, which can be used for actual product manufacturing, involves two dimensional image analysis using image processing technology. The thermal image analysis of the flat heating element is a programming technique that not only analyzes the heat generation state in both two and three dimensions, but also displays the upper and lower 15 to 20% ranges of temperature corresponding to the heat generation in the image. In the final analysis, it is possible to easily find the erroneous part in the manufacturing process by directly showing the state of the fabricated flat heating element on the screen. By combining this image analysis method of the flat heating element with the existing method, we were able to more accurately analyze the heat generation state.