• Title/Summary/Keyword: 소재유동

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Analysis of axisymmetric closed-die forging using UBET (UBET를 이용한 축대칭 형단조 해석)

  • 김동원;김헌영;신수정
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.3
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    • pp.337-344
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    • 1989
  • The upper bound elemental technique (UBET) is used to simulate the bulk flow characteristics in axisymmetric closed die forging process. Internal flow inside the cavity is predicted using a kinematically admissible velocity field that minimizes the rate of energy consumption. Application of the technique includes an assessment of the formation of flash and of degree of filling in rib-web type cavity using billets with various aspect rations. The technique considering bulging effect is performed in an incremental manner. The results of simulation show how it can be used for the prediction of forging load, metal flow, and free surface profile. The experiments are carried out with plasticine. There are good agreements in forging load and material flow in cavity between the simulation and experiment. The developed program using UBET can be effectively applied to the various forging problems.

Friction Welding Analysis of Welding Part Shape with Flow Gallery Considered Fluid Flow (유체 유동을 고려한 유동부를 갖는 용접부 형상의 마찰용접 해석)

  • Yeom, Sung-Ho;Kim, Bum-Nyun;Hong, Sung-In
    • Journal of the Korean Society of Propulsion Engineers
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    • v.11 no.3
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    • pp.7-12
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    • 2007
  • Friction welding is a welding method to use frictional heat of a couple of materials. In this paper object is that design the welding part shape with the flow gallery part which there is no effect in flow. Decided the welding part design parameter and doing the friction welding analysis used the rigid-plastic FEM program DEFORM-2D. To do friction welding analysis must input necessary flow stress data, friction coefficient by temperature change, upset pressure and Revolution per minute etc. According to analysis result, it decided the optimal shape of welding part with no effect in flow.

A study on the effect of surfactants on the streaming electrification of insulating oil (절연유의 유동대전에 미치는 계면활성제의 영향에 관한 연구)

  • 임헌찬;박재윤;김진식;김진식;이덕출
    • Electrical & Electronic Materials
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    • v.5 no.1
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    • pp.81-88
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    • 1992
  • 본 연구는 고체-액체 계면에서 액체가 유동할때 발생되는 대전에 미치는 계면 활성제의 영향에 대하여 분석한 것이다. 유동전류는 유속의 증가에 따라 선형적으로 증가하고 유온의 증가에 따라 약 46[.deg.C] 이하에서는 증가하고 그 이상에서는 감소한다. 계면활성제의 종도가 증가함에 따라 유동전류는 감소하고 계면활성제의 한 분자내 산소 원자의 수가 많을수록 유동전류의 감소효과가 크게 됨을 제시할 수 있다. 계면활성제가 첨가된 절연유의 전도전류는 온도에 따라 무첨가보다 다소 큰 경향이 있으나 첨가량에는 현저한 차이가 없다.

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Study on Temperature Characteristics of Friction Stir Welding Process by Numerical Analysis (수치해석을 활용한 마찰교반용접 공정의 온도 특성 분석 연구)

  • Kim, Moosun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.12
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    • pp.513-518
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    • 2019
  • Friction Stir Welding is a welding technique for metal materials that utilizes the heat generated by friction between the material to be welded and the welding tool that rotates at high speed. In this study, a numerical analysis method was used to analyze the change in the internal temperature of the welded material during friction stir welding. As the welding target material, AZ31 magnesium alloy was applied and the welding phenomenon was considered a flow characteristic, in which a melting-pool was formed. FLUENT was used as the numerical tool to perform the flow analysis. For flow analysis of the welding process, the welding material was assumed to be a high viscosity Newtonian fluid, and the boundary condition of the welding tool and the material was considered to be the condition that friction and slippage occur simultaneously. Analyses were carried out for various rotational speeds and the translational moving speed of the welding tool as variables. The analysis results showed that the higher the rotational speed of the welding tool and the slower the welding tool movement speed, the higher the maximum temperature in the material increases. Moreover, the difference in the rotational speed of the welding tool has a greater effect on the temperature change.

고집적 폴리머열교환기

  • O, Dong-Uk;Song, Chan-Ho;Park, Sang-Jin;Yun, Seok-Ho
    • Journal of the KSME
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    • v.54 no.5
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    • pp.45-48
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    • 2014
  • 이 글에서는 최근 각광 받고 있는 기능성 소재 중 하나인 열전도성 폴리머 소재를 열교환기에 적용하기 위한 열유동 설계 기술에 대하여 논한다. 또한 폴리머열교환기가 기존 금속재질 열교환기와 비교하여 가지는 장단점을 살펴보고, 폴리머열교환기의 상용화 가능성에 대한 고찰을 하였다.

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A study on the streaming electrification phenomena of the insulating oil flowing through the nozzle (세관을 통과하는 절연유의 유동대전에 관한 연구)

  • 이덕출;박재윤
    • Electrical & Electronic Materials
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    • v.3 no.4
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    • pp.332-338
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    • 1990
  • 본 연구는 절연유가 금속 파이프 중을 통과할 때 흐르는 유동전류 특성에 대하여 실험적으로 규명하였다. 유동전류는 파이프 길이, 절연유의 속도 및 온도에 따라 변하는 것이 관측되는데 파이프 길이가 4-6cm부근에서 피이크치가 나타나고 유속의 증가에 따라서는 선형적으로 증가하며 그리고 유의 온도가 약 50.deg.C 부근에서 또한 피이크가 나타나고 있다. 절연유에 전하를 주입시키는 수단으로 코로나 방전을 이용하였으며 부코로나 대전된 절연유의 유동전류가 코로나 대전 시키지 않은 절연유나 정코로나 대전된 절연유의 것보다 큰 값이 관측되었다. 이 결과로부터 고체 액체 접촉시 액체중의 음이온이 화학 포텐셜에 의하여 고체 표면에 흡착된다는 사실과 유동전류의 방향 및 발생기구를 해석할 수 있다.

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Finite Element Simulation of Material Flow and Weld Line Formation in SMC Compression Molding (SMC 압축성형의 소재유동과 겹침선 형성에 관한 유한요소 해석)

  • Hahn, Young-Won;Im, Yong-Taek
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.1
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    • pp.79-87
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    • 1996
  • SMC(Sheet Molding Compound) is made of unsaturated polyester resin and other additives reinforced with randomly distributed chopped fiberglass strands. Because of its higher stiffness per unit mass, SMC was used as a substitute for steel for automotive steel outer panels. Thus, understanding of flow characteristics during fabrication of SMC is of importance since the formation of weld line depends on material flow. In the present study, SMC compression molding simulations in the flat and T-shape molds were accomplished. During simulations, the preferential the preferential flow occurred at the low mold closing speed while plug flow was observed for the higher mold closing speed. When the preferential flow was observed, the weld line was seen at the final stage. For simulations, rigid-viscoplastic finite element method was applied. Self-contact algorithm was also applied in order to predict the formation of the weld line. Simulation results were compared to the experimental results available in the literature.

Investigation on the Size Effects of Polycrystalline Metallic Materials in Microscale Deformation Processes (미세성형 공정에서 다결정 금속재료의 크기효과에 관한 연구)

  • Kim, Hong-Seok;Lee, Yong-Sung
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.10
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    • pp.1463-1470
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    • 2010
  • Microforming, which exploits the advantages of metal forming technology, appears very promising in manufacturing microparts since it enables the production of parts using various materials at a high production rate, it has high material utilization efficiency, and it facilitates the production of parts with excellent mechanical properties. However, the conventional macroscale forming process cannot be simply scaled down to the micro-scale process on the basis of the extensive results and know-how on the macroscale process. This is because a so-called "size effect" occurs as the part size decreases to the microscale. In this paper, we attempt to develop an effective analytical and experimental modeling technique for explaining the effects of the grain size and the specimen size on the behavior of metals in microscale deformation processes. Copper sheet specimens of different thicknesses were prepared and heat-treated to obtain various grain sizes for the experiments. Tensile tests were conducted to investigate the influence of specimen thickness and grain size on the flow stress of the material. In addition, an analytical model was developed on the basis of phenomenological experimental findings to quantify the effects of the grain size and the specimen size on the flow stress of the material in microscale and macroscale forming.