• Title, Summary, Keyword: Bending Resistance

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Strength Properties and Elastic Waves Characteristics of Silicon Carbide with Damage-Healing Ability (손상치유 능력을 가지는 탄화규소의 강도 특성과 탄성파 특성)

  • KIM MI-KYUNG;AHN BYUNG-GUN;KIM JIN-WOOK;PARK IN-DUCK;AHN SEOK-HWAN;NAM KI-Woo
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • pp.337-341
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    • 2004
  • Engineering ceramics have superior heat resistance, corrosion resistance, and wear resistance. Consequently, these art significant candidates for hot-section structural components of heat engine and the inner containment of nuclear fusion reactor. Besides, some of them have the ability to heal cracks and great benefit can be anticipated with great benefit the structural engineering field. Especially, law fracture toughness of ceramics supplement with self-healing ability. In the present study, we have been noticed some practically important points for the healing behavior of silicon nitride, alumina, mullite with SiC particle and whisker. The presence of silicon carbide (SiC) in ceramic compound is very important for crack-healing behavior. However, self-healing of SiC has not been investigated well in detail yet. In this study, commercial SiC was selected as sample, which can be anticipated in the excellent crack healing ability. The specimens were produced three-point bending specimen with a critical semi-circular crack of which size that is about $50-700{\mu}m$. Three-point bending test and static fatigue test were performed cracked and healed SiC specimens. A monotonic bending load was applied to cracked specimens by three-point loading at different temperature. The purpose of this paper is to report Strength Properties and Elastic Waves Characteristics of Silicon Carbide with Crack Healing Ability.

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Experimental Verification of Set-Up Reference Values for the Determination of Downcoiling Tension in Hot Strip Mill (열간압연시 권취장력 설정기준치의 실험적 검증)

  • 공성락;강용기;김영환;문영훈
    • Transactions of Materials Processing
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    • v.10 no.1
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    • pp.53-58
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    • 2001
  • Set-up reference values, used in determining the optimum downcoiling tension, we experimentally verified in this study. During the actual downcoiling, the strip suffers both tension and bending force through the rotation of mandrel. Therefore, simulative test which can measure both tension and bending resistance of strip was performed to estimate set-up reference value for strip tension during downcoiling operations. The values obtained from the simulative test were correlated with the yield stress which has conventionally been used as reference values for downcoiling tension. The correlative analysis showed that the yield stress of strip can be a good reference value for downcoiling tension. Furthermore, the bending load also shows strong correlation with simulated values due to the close relationship between yield stress and bending load.

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Lifetime Estimation for FPCB of Slide mobile phone (슬라이드형 휴대폰 FPCB(Flexible Printed Circuit Board)의 수명예측)

  • Choi, Jin-Young;Chang, Seog-Weon;Kwack, Kae-Dal
    • Proceedings of the KSME Conference
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    • pp.1283-1288
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    • 2008
  • The FPCB is used as the important component of the sliding mechanism of mobile phones. FPCB have been used as jumper cables(fixed wiring) in various types of circuits because of their flexibility and bending property. The dominant failure mode of the FPCB is open that was caused by fatigue. The fatigue is repeated whenever the sliding is open, so it is a mainly cause of FPCB fatigue. We examined the bending-fatigue lifetime of FPCB. we focused on observing the contact resistance degradation of FPCB of mobile phones according to different test condition of bending strain. As a result, it has proved that lifetime decreased by increasing bending strain.

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The Development of Inner Structure of Metallic Sandwich Plates for Bending (굽힘성형을 위한 금속 샌드위치판재의 내부구조재 개발)

  • Seong, D.Y.;Jung, C.G.;Yoon, S.J.;Shim, D.S.;Lee, S.H.;Ahn, D.G.;Yang, D.Y.
    • Transactions of Materials Processing
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    • v.15 no.2
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    • pp.126-131
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    • 2006
  • Metallic sandwich plates are ultra-light materials not only with high strength and stiffness but also with other multifunctional physical properties. Inner dimpled shell structure can be fabricated by a piecewise sectional forming process, and then bonded with face sheets of the same material by resistance welding. Possible region for bending and limit radius of curvature are defined to compare the formability of sandwich plates. Tests have shown that sandwich plates with inner dimpled shell structure subject to bending have longer possible region for bending and smaller limit radius of curvature than other types of sandwich plates. The proposed inner dimpled shell structure is shown to have better formability of sandwich plates for bending than other types inner structures.

Shear Resisting Effects of Protruded Nails by Pressure Grouting (가압식 돌기네일의 전단저항 효과)

  • Hong, Cheorhwa;Lee, Sangduk
    • Journal of the Korean Geoenvironmental Society
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    • v.18 no.7
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    • pp.13-20
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    • 2017
  • Soil nailing is ground reinforcement method using the shear strength of ground and the pullout shear resistance force of nail. It is mainly used for reinforcement of cut slopes, earth retaining structures and retaining walls, etc. It may be designed considering the pullout resistance of nail in the case of earth retaining structure and retaining wall, but it should be designed considering not only pullout resistance but also shear and bending resistance in the case of slope. However, conservative designs considering only pullout resistance are being done and most of the studies are about increasing pullout resistance by improving of material, shape and construction method of nail. Actually, Shear bending deformations occur centering on the active surface in ground reinforced with the nail. The grout with relatively low strength is destroyed and separated from the reinforcing material. As a result, the ground is collapsed while reducing the frictional resistance rapidly. Therefore, it is necessary to develop the method to increase the shear resistance while preventing separation of nail and grout body. In this study, an experimental study was conducted on new soil nailing method which can increase shear resistance by forming protrusions through pressurized grouting after installing a packer on the outside of deformed bar.

Studies on Morphological and Physical Characteristics of Wheat and Barley Culms under Different Cultural Conditions 1. Effects of Top-Dressing Time of Nitrogen on Morphological and Physical Characteristics of Barley Culms (재배조건에 따른 맥간의 형태적 및 생리적 특성변화에 관한 연구 I. 질소추비시기가 맥간의 형태적 및 생리적특성에 미치는 영향)

  • Hong-Suk Lee;Chang-Hwan Cho
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.14
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    • pp.117-121
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    • 1973
  • This experiment was conducted to study the effects of nitrogen top-dressed at the different growth stages on the morphological and physical characteristics of barley culm. The results obtained are summarized as follows: 1. By top-dressing of nitrogen in March, each internode length from the third to the fifth internode was shortened, and total fresh weight of the top, dry weight per unit culm, inside or outside culm diameter and thickness of culm were increased. Therefore these characteristics related to lodging indicated the beneficial changes for lodging resistance by top-dressing of nitrogen in March. 2. Both weight of culm at breaking and bending moment of culm at breaking, expressing lodging resistance of culm, were increased in the plots of nitrogen top-dressed in March. Accordingly lodging resistance became higher by top-dressing of nitrogen in March. 3. Both section modulus and secondary moment of inertia, expressing bending stiffness of culm, were increased by top-dressing of nitrogen in March. Accordingly lodging index, expressing comprehensive lodging resistance, became low by top-dressing of nitrogen in March. 4. Both spike weight and grain yield were increased by top-dressing of nitrogen in March. Consequently we came to the conclusion that the suitable top-dressing time of nitrogen was in March.

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Performance Analysis Based on Bonded Surface Designs for Stitchless Welded Products

  • Kim, Keum-Wha;Choi, Hei-Sun
    • Journal of the Korean Society of Clothing and Textiles
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    • v.36 no.6
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    • pp.583-591
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    • 2012
  • This study selected three model designs used for air injection type welding clothes designed for insulation purposes and analyzed the performance of each design. The bending characteristics were analyzed in order to identify the flexibility of the welded areas; subsequently, the seam breaking strength and water pressure resistance were analyzed to identify the bonding strength. In addition, two types of waterproof fabric, polyurethane (PU) coated 2 layer and PU laminated 2 layer fabrics, were used for a performance analysis, according to fabric processing specifications. The circle type showed the highest flexibility in the terms of bending characteristics that influence wearability and were followed by the wave and the straight type. In terms of breaking strength, the straight type showed the highest breaking strength, followed by the wave and the circle type. The water pressure resistance analysis found that the wave type was superior to the straight type in terms of water pressure resistance. The wave type is deemed to be a design type suitable for maximizing performance, provided that the issue of stabilization in the welding production process is addressed. Looking at the bending characteristics of waterproof fabric for each specification, the laminating waterproof cloth outperformed the coated waterproof cloth in terms of flexibility. However, in terms of seam breaking strength, the coated waterproof cloth outperformed the laminated cloth. In contrast, the water pressure resistance of the laminated waterproof fabric was found to be higher than the coated waterproof fabric, leading to the conclusion that the bonding strength of the laminated waterproof fabric is higher than that of the coated waterproof fabric based on the assumption of injecting air.

Bend Resistance of Polymer Cement Slurry Coated Reinforcing bars (폴리머 시멘트 슬러리 도장철근의 내굴곡성)

  • 김현기;김민호;장성주;김완기;소양섭
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.1017-1022
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    • 2001
  • The bend resistance of coated reinforcing bar is greatly influenced by adhesion strength of bar and coating materials and transformation of coating materials to the bar. Expecially, tearing state or a limited microscopic cracks are predicted on the inside and outside of bending angle because of adhesion strength and elongation is very different with types of polymer materials using bar coating, and these parts are accelerated corrosion as penetration of bar corrosion effects factor. In this study, cement modified polymer are prepared four types and differ from polymer cement ratio of 50% and 100%, coating thickness of 250$\mu$m and 450$\mu$m, coating number, curing age of 3, 7, 14 and 280days, and then tested bend resistance as bending angle $90^{\circ}$, $135^{\circ}$ and $180^{\circ}$ for observe the microscopic demage effect according as bar bend. From the test results, when is used cement modified polymer as coating materials of bar, St/BA is showed excellent bend resistance than a polyacrylic emulsion and SBR because of softness. But it is to need attention because as coating parts are pressed down and tearing, also experimental study is proceeded to corrosion potential on the inside and outside of coated reinforcing bar.

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The Study on Field Performance Test of Multi Branch Type Tie(GOLRY TIE) (다지형 침목 현장 성능평가에 관한 연구)

  • Kim, Hae-Gon;Suh, Dong-Seok;Kim, Nam-Hong;Lee, Syeung-Youl
    • Proceedings of the KSR Conference
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    • pp.162-166
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    • 2011
  • In railway, Tie supports rail and plays a role that distribute train load to the ballast. Also, Tie and ballast resist against external force and fix the track position. But, weakening resistance of ballast and tie cause vertical displacement of tie and track irregularity. For reinforcement of track stiffness and reduction of track irregularity, KORAIL has developed Multi Branch type tie(GLORY Tie) that reinforced resistance than general PCT and installed in order to test in the field. This study measured and analyzed lateral resistance of ballast, wheel load of rail, bending strain of rail foot, vertical displacement and vibration acceleration of tie in order to evaluate performance of Multi Branch type tie in the field. According to the results of test, Multi Branch tie is excellent than general tie about lateral resistance of ballast and vertical displacement of tie. And, gap of measurement value between Multi Branch type tie and general tie about wheel load of rail, bending strain of rail foot were very small.

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Investigation on the flexural behavior of an innovative U-shaped steel-concrete composite beam

  • Turetta, Maxime;Odenbreit, Christoph;Khelil, Abdelouahab;Martin, Pierre-Olivier
    • Steel and Composite Structures
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    • v.34 no.3
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    • pp.441-452
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    • 2020
  • Within the French CIFRE research project COMINO, an innovative type of composite beam was developed for buildings that need fire resistance with no additional supports in construction stage. The developed solution is composed of a steel U-shaped beam acting as a formwork in construction stage for a reinforced concrete part that provides the fire resistance. In the exploitation stage, the steel and the reinforced concrete are acting together as a composite beam. This paper presents the investigation made on the load bearing capacity of this new developed steel-concrete composite section. A full-scale test has been carried out at the Laboratory of Structural Engineering of the University of Luxembourg. The paper presents the configuration of the specimen, the fabrication process and the obtained test results. The beam behaved compositely and exhibited high ductility and bending resistance. The shear connection in the tension zone was effective. The beam failed by a separation between the slab and the beam at high deformations, excessive shear forces conducted to a failure of the stirrups in this zone. The test results are then compared with good agreement to analytical methods of design based on EN 1994 and design guidelines are given.