• Title/Summary/Keyword: Multilayered Sheet

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Prediction for Thickness and Fracture of Stainless Steel-Aluminum-Magnesium Multilayered Sheet during Warm Deep Drawing (온간 딮 드로잉에서 이종금속판재(STS430-Al3004-AZ31)의 파단 및 두께 예측을 위한 연구)

  • Lee, Y.S.;Lee, K.S.;Kim, D.
    • Transactions of Materials Processing
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    • v.21 no.1
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    • pp.49-57
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    • 2012
  • It is difficult to estimate the properties of multilayered sheet because they are composed of one or more different materials. Plastic deformation behavior of the multilayered sheet is quite different as compared to each material individually. The deformation behavior of multilayered sheet should be investigated in order to prevent forming defects and to predict the properties of the formed part. In this study, the mechanical properties and formability of stainless steel-aluminum-magnesium multilayered sheet were investigated. The multilayered sheet needs to be deformed at an elevated temperature because of its poor formability at room temperature. Uniaxial tensile tests were performed at various temperatures and strain rates. Fracture patterns changed mainly at a temperature of $200^{\circ}C$. Uniform and total elongation of multilayered sheet increased to values greater than those of each material when deformed at $250^{\circ}C$. The limiting drawing ratio (LDR) was obtained using a circular cup deep drawing test to measure the formability of the multilayered sheet. A maximum value for the LDR of about 2 was achieved at $250^{\circ}C$, which is the appropriate forming temperature for the Mg alloy. Fracture patterns on a circular cup and thickness of formed part were predicted by a rigid-viscoplastic FEM analysis. Two kinds of modeling techniques were used to simulate deep drawing process of multilayered sheet. A single-layer FE-model, which combines the three different layers into a macroscopic single layer, predicted well the thickness distribution of the drawn cup. In contrast, the location and the time of fracture were estimated better with a multi-layer FE model, which used different material properties for each of the three layers.

Temperature and Strain Rate Dependent Tension Properties of Stainless Steel-Aluminum-Magnesium Multilayered Sheet Fabricated by Roll Bonding (롤 아연된 STS-Al-Mg 이종금속판재의 온도와 변형률속도에 따른 1축인장 변형특성)

  • Hwang, B.K.;Lee, K.S.;Hong, S.E.;Lee, Y.S.
    • Transactions of Materials Processing
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    • v.20 no.3
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    • pp.257-264
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    • 2011
  • Multilayer(clad) sheets, composed of two or more materials with different properties, are fabricated using the roll-bonding process. A good formability is an essential property for a multilayered sheet in order to manufacture parts by plastic deformation. In this study, the influences of temperature and strain rate on the plastic properties of stainless steel-aluminum-magnesium multilayered(STS-Al-Mg) sheets were investigated. Tensile tests were performed at various temperatures and strain rates on the multilayered sheet and on each separate layer. Fracture of the multilayered sheet was observed to be temperature-dependent. At the base temperature of $200^{\circ}C$, all materials fractured simultaneously. At lower temperatures, the Mg alloy sheet fractured earlier than the other materials. Conversely, the other materials fractured earlier than the Mg alloy sheet at higher temperatures. The uniform and total elongations of the multilayered sheet were observed to be higher than that of each material at a temperature of $250^{\circ}C$. Larger uniform elongations were obtained for higher strain rates at constant temperature. The same trend was observed for the Mg alloy sheet, which exhibited the lowest elongation among the three materials. The tensile strengths and elongations of the single layer sheets were compared to those of the multilayer material. The strength of the multilayered sheet was successfully calculated by the rule of mixture from the values of each single layer. However, no simple correlation between the elongation of each layer and that of the multilayer was obtained.

Predicting Mechanical Response of Multilayered Aluminum Sheet Using Finite Element Analysis (유한요소해석 연계 알루미늄 다층판재의 기계적 거동 예측)

  • Sung, J.Y.;Kim, M.H.;Bong, H.J.;Lee, K.S.;Kim, M.J.;Kim, J.H.
    • Transactions of Materials Processing
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    • v.29 no.6
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    • pp.347-355
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    • 2020
  • The mechanical responses of multilayered aluminum sheet fabricated by roll bonding, i.e., A1050/A3004 (65% A1050, 35% A3004 by thickness), were investigated via combined experiment and finite element (FE) analysis. The mechanical properties were measured using uniaxial tensile tests in various loading directions for the multilayered sheet. The corresponding tests for individual layers were also conducted. The testing samples were prepared by wire electro discharge machining (EDM). Stress-strain curves and Lankford coefficients of the multilayered sheet were then predicted by FE simulations. The measured mechanical properties of the individual layers were utilized as inputs for the simulation. Two yield functions, i.e., isotropic von-Mises and anisotropic non-quadratic Hill1948, were employed. Predicted results were compared with the experimental data and further discussed.

Multilayered Graphene Electrode using One-Step Dry Transfer for Optoelectronics

  • Lee, Seungmin;Jo, Yeongsu;Hong, Soonkyu;Kim, Darae;Lee, Hyung Woo
    • Current Optics and Photonics
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    • v.1 no.1
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    • pp.7-11
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    • 2017
  • In this study, multilayered graphene was easily transferred to the target substrate in one step using thermal release tape. The transmittance of the transferred graphene according to the number of layers was measured using a spectrophotometer. The sheet resistance was measured using a four-point probe system. Graphene formed using this transfer method showed almost the same electrical and optical properties as that formed using the conventional poly (methyl methacrylate) transfer method. This method is suitable for the mass production of graphene because of the short process time and easy large-area transfer. In addition, multilayered graphene can be transferred on various substrates without wetting problem using the one-step dry transfer method. In this work, this easy transfer method was used for dielectric substrates such as glass, paper and polyethylene terephthalate, and a sheet resistance of ~240 ohm/sq was obtained with three-layer graphene. By fabricating organic solar cells, we verified the feasibility of using this method for optoelectronic devices.

Membrane을 이용한 삼중수소 제거 촉매탑 설계

  • 김광신;손순환;송규민
    • Proceedings of the Korean Nuclear Society Conference
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    • 1998.05b
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    • pp.427-432
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    • 1998
  • 중수속의 삼중수소 제거 공정인 액상 촉매 교환 반응에서 중수의 촉매 표면 응축에 의한 성능 저하가 큰 문제의 하나로서 성능 저하를 감소시키기 위한 여러 가지 형태의 촉매탑이 고안 되었다. 본 연구에서는 membrane을 사용하여 중수와 촉매를 분리시킴으로써 촉매 성능 저하를 감소시킬 수 있는 촉매탑의 설계를 시도하였다. 세 가지 촉매탑이 고안되었는데 sheet type의 membrane을 사용한 multilayered type 과 double spiral type, hollow fiber membrane을 사용한 hollow fiber cartridge type 등이다. multilayered type은 구조가 단순하여 scale-up이 용이하고 double spiral type은 다른 type보다 유로의 blocking 문제가 작고 hollow fiber cartridge type은 최대의 비표면적을 가질 수 있다.

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Inhomogeneous Rolling Texture of Multilayered Aluminum Sheet (다층압연된 알루미늄의 불균질압연집합조직)

  • Choi, Chang-Hee;Hong, Seung-Hyun;Kwon, Jae-Wook;Oh, Kyu-Hwan;Lee, Dong-Nyung
    • Transactions of Materials Processing
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    • v.4 no.4
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    • pp.353-364
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    • 1995
  • An inhomogeneous rolling texture of high purity aluminum has been observed by a multilayered rolling. The shear texture of (100)[110] component developed in the surface layer, and the copper type rolling texture developed in the middle and center layers. The through-thickness texture variation has been calculated by the full-constraint Taylor model combined with FEM. The calculated results are in good agreement with the measured data.

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A study on fatigue life of Al 7075/CFRP multilayered hybrid composite materials (Al 7075/CFRP 다적층 하이브리드 복합재료의 피로수명에 대한 연구)

  • 윤한기;김연겸;박준수;이경봉
    • Journal of Ocean Engineering and Technology
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    • v.10 no.4
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    • pp.92-102
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    • 1996
  • In this research, to develope the A1 7075/CFRP multilayered hybrid composites, CRALL(Carbon Reinforced aluminum lamiate) specimens were processed by autoclavecuring system that curing temperature, time, surface pretreatment condition of aluminum were constant. Andthe fatigye life and failure mechanism on CFRP volume fraction and fiber orientation of CRALLspecimens were investigated. A fatigue life was greatly influenced by effect of CFRP fiber volume fraction but it was less effected than those of fiber orientation. The fatigue failure arised from interface delamination of CFRP and aluminum sheet after shear fracture of aluminum layer. The failure mechanism is assumed that the aluminum laminates which divide the CFRP into many thim layers tend to arrest the failure propagation.

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Effect of ZnO Buffer Layers on the Crystallization of ITO Thin Film at Low Temperature

  • Seong, Chung-Heon;Shin, Yong-Jun;Jang, Gun-Eik
    • Transactions on Electrical and Electronic Materials
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    • v.13 no.4
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    • pp.208-211
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    • 2012
  • In the present study, a ZnO thin film, as a buffer layer of ITO (indium tin oxide) film was deposited on glass substrates by RF magnetron sputtering at low temperature of $150^{\circ}C$. In order to estimate the optical characteristics and compare with the experimental results in Glass/ZnO(100 nm)/ITO(35 nm) multilayered film, the simulation program, EMP (Essential Macleod Program) was adopted. The sheet resistance and optical transmittance of the films were measured using the four-point probe method and spectrophotometer, respectively. From X-ray diffraction patterns, all the films deposited at $150^{\circ}C$ demonstrated only the amorphous phase. Optical transmittance was the highest at a ZnO thickness of 100 nm. The ITO(35 nm)/ZnO(100 nm) film exhibits an optical transmittance of >92% at 550 nm. The multilayered film showed an electrical sheet resistance of 407 ${\Omega}/sq.$, which is significantly better than that of a single-layer ITO film without a ZnO buffer layer (815 ${\Omega}/sq.$).

Fabrication of Microfibrous Structures with Rolled-Up Forms using a Bilayer Self-Assembly Process (이중층 자가조립 공정을 활용한 롤형태의 생체의료용 마이크로섬유 구조체 제작)

  • Kim, Yeong-Seo;Park, Suk-Hee
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.21 no.2
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    • pp.79-86
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    • 2022
  • Numerous fabrication techniques have been used to mimic cylindrical natural tissues, such as blood vessels, tendons, ligaments, and skeletal muscles. However, most processes have limitations in achieving the biomimetic properties of multilayered and porous architectures. In this study, to embrace both features, a novel self-assembly method was proposed using electrospun microfibrous sheets. A bilayer microfibrous structure, comprising two sheets with different internal stresses, was fabricated by electrospinning a polycaprolactone (PCL) sheet on a uniaxially stretched thermoplastic polyurethane (TPU) sheet. Then, by removing the stretching tension, the sheet was rolled into a hollow cylindrical structure with a specific internal diameter. The internal diameter could be quantitatively controlled by adjusting the thickness of the PCL sheet against that of the TPU sheet. Through this self-assembly method, biomimetic cylindrical structures with multilayer and porous features can be manufactured in a stable and controllable manner. Therefore, the resulting structures may be applied to various tissue engineering scaffolds, especially vascular and connective tissues.

Changes of Camber on Lamination Conditions in alumina/Tungsten Cofiring Multilayer Package (알루미나/텅스텐 동시소성에 의한 다층 팩키지 제조시 적층조건에 따른 camber의 변화)

  • 성재석;구기덕;윤종광;이상진;박정현
    • Journal of the Korean Ceramic Society
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    • v.34 no.6
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    • pp.601-610
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    • 1997
  • In cofiring of multilayered alumina with tungsten, the change of camber with lamination condition was experimented and the effect of sintering shrinkage of alumina and tungsten was investigated. From the exact measurement of sintering shrinkage of tungsten thick film, as lamination pressure increased, the sintering shrinkage of alumina decreased but that of tungsten thick film was not changed. So it was though that the main factor which induced the sintering shrinkage difference between ceramics and metal with lamination condition was the change of sintering shrinkage of ceramics. In case of high lamination pressure, high green sheet density, the cofired specimen showed low camber due to low shrinkage difference between alumina and tungsten and there was a linear relation between camber and shrinkage difference. It was found that this shrinkage difference could change the thickness of tungsten film and the microstructure within via hole during cofiring.

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