• 제목/요약/키워드: tubes

검색결과 3,122건 처리시간 0.027초

핵연료 피복관용 지르칼로이-4의 미세조직과 기계적 특성에 미치는 $\beta$-열처리의 영향 (The Effect of $\beta$-Heat Treatment on the Microstructure and Mechanical Characteristics of Zircaloy-4 for Nuclear Fuel Cladding)

  • 고진현;오영근;김광수
    • 한국재료학회지
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    • 제9권6호
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    • pp.589-594
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    • 1999
  • The effect of $\beta$-heat treatment on th microstructure, mechanical properties and texture in the nuclear fuel cladding of Zircaloy-4 tubes was chosen at 1000, 1100 and 120$0^{\circ}C$, and the tubes were heat-treated by a high frequency vacuum induction furnace. Morphology of the second phase particles and $\alpha$-grain of as-received tubes were markedly changed by heat treatment. The average sizes of second phase particles of as-received and $\beta$-heat treated tubes were 0.1$\mu\textrm{m}$ and 0.076$\mu\textrm{m}$, respectively. However, the average sizes of second phase particles were not much changed in the $\beta$-heated temperatures. With increasing heat treatment temperatures, the 0.2% yield strength and the hoop strength were decreased because of changes in preferred orientation as will as $\alpha$-plate width. Heat treated Zircaloy-4 tubes exhibited texture changes but the preferred orientation of grains still remained.

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A Study on 3-Dimensional Profilometry of Steam Generator Tube Using a New Eddy Current Probe

  • Kim, Young-Kyu;Song, Myung-Ho;Choi, Myung-Sik
    • 비파괴검사학회지
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    • 제30권3호
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    • pp.225-235
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    • 2010
  • There are many types of the geometric transitions such as dent, bulge, protrusion, expansion, etc, on the inner and outer surfaces of heat exchanger tubes, steam generator tubes, and condenser tubes of nuclear power plants. Such geometric transition causes a local residual stress in heat exchanger tubes and acts as a structural factor accelerating the evolution of defects, in particular stress corrosion cracks. In the conventional eddy current test methods, the bobbin coil profilometry can provide 2-dimensional geometric information on the variation of the average inner diameter along the tube length, but the 3-dimensional distribution and the quantitative size of a local geometric transition existing in the tube cannot be measured. In this paper, a new eddy current probe, developed for the 3-dimensional profile measurement, is introduced and its superior performance is compared with that from the conventional bobbin coil profilometry for the various types of geometric transition. Also, the accuracy of the probe for the quantitative profile measurement is verified by comparing the results with that from the laser profilometry. It is expected that the new eddy current probe and techniques can be effectively used for an optimization of the tube expansion process, and the management of tubes with geometric transitions in service.

작은 수직관을 흐르는 기-액 슬러그 유동의 유동특성 (Flow Characteristics of a Gas-Liquid Slug Flow in Small Vertical Tubes)

  • 계석현;김동선
    • 설비공학논문집
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    • 제25권5호
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    • pp.246-254
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    • 2013
  • Some characteristics of nitrogen-water slug flow were optically measured, in vertical acrylic tubes of 2, 5 and 8 mm diameter. Bubble velocity, bubble and unit cell lengths were measured, by analyzing the light intensity signals from two sets of dot laser-infrared sensor modules mounted along the transparent tubes. Optical images of the bubbles were also taken and analyzed, to measure bubble shapes and liquid film thickness. It was found that the measured bubble velocities were in good agreement with the empirical models in the literature, except for those measured under high superficial velocity condition in the 2 mm tube. Bubble length was found to be the longest in the 2 mm tube, being 4 to 5 times those of the other tubes. Liquid film was found to have developed early in the 2 mm tube, which made the blunt shape of the bubble head. Liquid film thickness in the 8 mm tube was measured at almost twice those of the other tubes.

Pitting Corrosion Inhibition of Sprinkler Copper Tubes via Forming of Cu-BTA Film on the Inner Surface of Corrosion pits

  • Suh, Sang Hee;Suh, Youngjoon;Kim, Sohee;Yang, Jun-Mo;Kim, Gyungtae
    • Corrosion Science and Technology
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    • 제18권2호
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    • pp.39-48
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    • 2019
  • The feasibility of using benzotriazole (BTAH) to inhibit pitting corrosion in the sprinkler copper tubes was investigated by filling the tubes with BTAH-water solution in 829 households at an eight-year-old apartment complex. The water leakage rate was reduced by approximately 90% following BTAH treatment during 161 days from the previous year. The leakage of one of the two sprinkler copper tubes was investigated with optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis to determine the formation of Cu-BTA film inside the corrosion pits. All the inner components of the corrosion pits were coated with Cu-BTA films suggesting that BTAH molecules penetrated the corrosion products. The Cu-BTA film was about 2 nm in thickness at the bottom of a corrosion pit. A layer of CuCl and $Cu_2O$ phases lies under the Cu-BTA film. This complex structure effectively prevented the propagation of corrosion pits in the sprinkler copper tubes and reduced the water leakage.

Concrete filled double skin square tubular stub columns subjected to compression load

  • Uenaka, Kojiro
    • Structural Engineering and Mechanics
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    • 제77권6호
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    • pp.745-751
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    • 2021
  • Concrete filled double skin tubular members (CFDST) consist of double concentric circular or square steel tubes with concrete filled between the two steel tubes. The CFDST members, having a hollow section inside the internal tube, are generally lighter than ordinary concrete filled steel tubular members (CFT) which have a solid cross-section. Therefore, when the CFDST members are applied to bridge piers, reduction of seismic action can be expected. The present study aims to investigate, experimentally, the behavior of CFDST stub columns with double concentric square steel tubes filled with concrete (SS-CFDST) when working under centric compression. Two test parameters, namely, inner-to-outer width ratio and outer square steel tube's width-to-thickness were selected and outer steel tube's width-to-thickness ratio ranging from 70 to 160 were considered. In the results, shear failure of the concrete fill and local buckling of the double skin tubes having largest inner-to-outer width ratio were observed. A method to predict axial loading capacity of SS-CFDST is also proposed. In addition, the load capacity in the axial direction of stub column test on SS-CFDST is compared with that of double circular CFDST. Finally, the biaxial stress behavior of both steel tubes under plane stress is discussed.

필라멘트 와인딩 공법 GFRP 원형 튜브의 에너지 흡수특성에 관한 연구 (A Study on the energy absorption characteristics of GFRP circular tubes fabricated by the filament winding method)

  • 김거영;구정서
    • Composites Research
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    • 제22권4호
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    • pp.1-12
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    • 2009
  • 본 논문에서는 복합재 원형튜브의 에너지 흡수 특성을 평가하기 위해 준정적 압괴실험을 시행하였다. 사용된 시편은 필라멘트 와인딩 공법으로 제작된 GFRP(유리섬유/에폭시수지) 원형 튜브이다. 복합재 튜브의 에너지 흡수 특성 분석을 위한 파라미터로서 튜브의 트리거메커니즘, t/D, 섬유배향각 등을 고려하여 그 특성을 비교하였다. 튜브의 형상 측면에서 튜브 직경이 커짐에 따라 delamination에 의한 국부좌굴 발생빈도가 증가하게 되어 불안정한 압괴모드가 발생하는데 이러한 현상은 섬유 배향각을 조정하여 안정적인 압괴모드를 도출할 수 있었다.

Optimization and investigations of low-velocity bending impact of thin-walled beams

  • Hossein Taghipoor;Mahdi Sefidi
    • Steel and Composite Structures
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    • 제50권2호
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    • pp.159-181
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    • 2024
  • In the present study, the effect of geometrical parameters of two different types of aluminum thin-walled structures on energy absorption under three-bending impact loading has been investigated experimentally and numerically. To evaluate the effect of parameters on the specific energy absorption (SEA), initial peak crushing force (IPCF), and the maximum crushing distance (δ), a design of experiment technique (DOE) with response surface method (RSM) was applied. Four different thin-walled structures have been tested under the low-velocity impact, and then they have simulated by ABAQUS software. An acceptable consistency between the numerical and experimental results was obtained. In this study, statistical analysis has been performed on various parameters of three different types of tubes. In the first and the second statistical analysis, the dimensional parameters of the cross-section, the number of holes, and the dimensional parameter of holes were considered as the design variables. The diameter reduction rate and the number of sections with different diameters are related to the third statistical analysis. All design points of the statistical method have been simulated by the finite element package, ABAQUS/Explicit. The final result shows that the height and thickness of tubes were more effective than other geometrical parameters, and despite the fact that the deformations of the cylindrical tubes were around forty percent greater than the rectangular tubes, the top desirability was relevant to the cylindrical tubes with reduced cross-sections.

내부 구속 중공 CFT 교각의 내진성능에 대한 매개변수 연구 (Parametric Study on Seismic Performance of Internally Confined Hollow CFT Column)

  • 김현종;염응준;한택희;강영종
    • 한국방재학회:학술대회논문집
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    • 한국방재학회 2007년도 정기총회 및 학술발표대회
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    • pp.144-147
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    • 2007
  • Internally Confined Hollow-Concrete Filled Tube(ICH-CFT) column which has two tubes on both side of concrete, inner tube and outer tube perform great seismic abilities, ductility and absorption of energy, by the tubes and the hollow part. So this study does qualitative analysis about seismic capacities depending on parameters - diameter of column, hollow ratio, thickness of tubes - by moment-curvature analysis.

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알루미늄 튜브 하이드로포밍의 성형한계 (Forming limits of aluminum tubes in tube hydroforming)

  • 조완제;이상영;김영석;이상용
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2003년도 춘계학술대회논문집
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    • pp.244-248
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    • 2003
  • Recently social demands of fuel economy and environmental regulations require the development of light materials and new manufacturing technologies. In this point, the aluminum tube hydroforming process which is satisfied with good strength-to-weight ratio and recyclability is innovative concept. However the level of the aluminum tube hydroforming technology is low in comparison with that of steel tube hydroforming. In this paper, the hydroformability of aluminum tubes in different heat treatments is presented. Theoretical results for forming limits of the wrinkling and bursting are compared with experimental results of aluminum tubes.

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순수굽힘 시험기개발 및 사각관부재의 굽힘붕괴특성 연구 (Development of a Pure Bending Test Machine and Bending Collapse Characteristics of Rectangular Tubes)

  • 강신유;장인배;김헌영
    • 한국자동차공학회논문집
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    • 제6권1호
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    • pp.222-233
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    • 1998
  • A 4-point pure bending res machine is developed the evaluate the pure vending moment-rotation properties of the thin-walled tubes without imposing shear and tensile forces. The moment-rotation properties of the thin-walled tubes are measured up to and beyond collapse with the pure bending test machine. The test results are compared with those of finite element analyses and existing analytical solution.

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