• Title/Summary/Keyword: Ultra-lightweight

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A Study on the Hydraulic and Heat Transfer Characteristics for the Wire-woven Bulk Kagome(WBK) Composed of Aluminum Helix Wires (알루미늄 나선형 와이어로 직조된 다층 Kagome truss PCM의 유동 및 열전달 특성에 관한 연구)

  • Joo, Jai-Hwang;Kang, Bo-Seon;Kang, Ki-Ju
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2061-2066
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    • 2007
  • Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the hydraulic and heat transfer characteristics for the Wire-woven Bulk Kagome(WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen have been experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK are compared with other heat dissipation media. It was shown that heat transfer depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and other materials suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

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A Study on the Fluid Flow and Heat Transfer Characteristics for the Wire-woven Bulk Kagome(WBK) Composed of Aluminum Helix Wires (알루미늄 나선형 와이어로 직조된 다층 Kagome Truss PCM의 유동 및 열전달 특성에 관한 연구)

  • Joo, Jai-Hwang;Kang, Bo-Seon;Kang, Ki-Ju
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.1
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    • pp.15-22
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    • 2008
  • Recently, ultra-lightweight materials with open, periodic cell structures take much attention owing to its potential for multi-functionality such as load bearing, thermal dissipation, and actuation. This paper presents experimental results on the fluid flow and heat transfer characteristics for the Wire-woven Bulk Kagome (WBK) composed of aluminum 1100 wires. The overall pressure drop and heat transfer of the WBK specimen was experimentally investigated under forced air convection condition. The pressure loss and heat transfer performance of the aluminum WBK were compared with other heat dissipation media. It was shown that heat transfer characteristics depended on relative density and surface area density. Comparison with metal foams and other heat dissipation media such as packed beds, lattice frame materials, louvered fins, and others suggests that the aluminum WBK competes favorably with the best available heat dissipation media in heat transfer performance.

Ultimate strength behavior of steel-concrete-steel sandwich beams with ultra-lightweight cement composite, Part 1: Experimental and analytical study

  • Yan, Jia-Bao;Liew, J.Y. Richard;Zhang, Min-Hong;Wang, Junyan
    • Steel and Composite Structures
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    • v.17 no.6
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    • pp.907-927
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    • 2014
  • Ultra-lightweight cement composite (ULCC) with a compressive strength of 60 MPa and density of $1450kg/m^3$ has been developed and used in the steel-concrete-steel (SCS) sandwich structures. ULCC was adopted as the core material in the SCS sandwich composite beams to reduce the overall structural weight. Headed shear studs working in pairs with overlapped lengths were used to achieve composite action between the core material and steel face plates. Nine quasi-static tests on this type of SCS sandwich composite beams were carried out to evaluate their ultimate strength performances. Different parameters influencing the ultimate strength of the SCS sandwich composite beams were studied and discussed. Design equations were developed to predict the ultimate resistance of the cross section due to pure bending, pure shear and combined action between shear and moment. Effective stiffness of the sandwich composite beam section is also derived to predict the elastic deflection under service load. Finally, the design equations were validated by the test results.

Experimental Review on Application of Lightweight UHPC as Repair Mortar and Cement Panel (경량 UHPC의 보수용 모르타르 및 시멘트 패널로서의 활용 가능성에 대한 실험적 검토)

  • Jae Sung Ahn;Hyeong-Ki Kim
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.11 no.3
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    • pp.210-217
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    • 2023
  • Various performances of ultra-high performance concrete (UHPC) applied with microplastics and expanded polystyrene (EPS) beads were evaluated. CompressIve and flexural strength, performance after ignition, flow-down in fresh state, and effective bond strength were evaluated. Designed weight of the cement panel with these mixtures was calculated based on the flexural strength. As a result of the experiments, it was confirmed that the EPS could reduce the density of UHPC with largest range. By maximum addition of EPS beeds, the density of UHPC decreased to 1300 kg/m3, and the compressive and flexural strengths for this mixtures were in ranges of 20-30 MPa and 15-20 MPa, respectively. On the other hand, lightest cement panel could be designed with UHPC having a density ranges about 2.0 g/cm3.

Practical Ultraprecision Positioning of a Ball Screw Mechanism

  • Sato, Kaiji;Maeda, Guilherme Jorge
    • International Journal of Precision Engineering and Manufacturing
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    • v.9 no.2
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    • pp.44-49
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    • 2008
  • This paper describes the problem of ultraprecision positioning with a ball screw mechanism in the microdynamic range, along with its solution. We compared the characteristics of two ball screw mechanisms with different table masses. The experimental results showed that the vibration resulting from the low stiffness of the ball screw degraded the positioning performance in the microdynamic range for the heavyweight mechanism. The proposed nominal characteristic trajectory following (NCTF) controller was designed for ultra precision positioning of the ball screw mechanism. The basic NCTF control system achieved ultra precision positioning performance with the lightweight mechanism, but not with the heavyweight mechanism. A conditional notch filter was added to the NCTF controller to overcome this problem. Despite the differences in payload and friction, both mechanisms then showed similar positioning performance, demonstrating the high robustness and effectiveness of the improved NCTF controller with the conditional notch filter. The experimental results demonstrated that the improved NCTF control system with the conditional notch filter achieved ultra precision positioning with a positioning accuracy of better than 10 nm, independent of the reference step input height.

A Study on the forming Process of Automobile Center floor Side Member using Ultra High Strength Steel of 980MPa (980MPa급 초고강도강판을 이용한 센터 플로 사이드 멤버의 성형공정 연구)

  • Lim, H.T.;Suh, C.H.;Youn, K.T.;Ro, H.C.;Shin, H.D.;Kwak, Y.S.;Park, C.D.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.203-206
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    • 2009
  • Ultra high strength steels(UHSS) are widely used to fill the needs of lightweight part for automobile, and the control of springback is very important (actor in sheet metal forming using UHSS. In this study, to lighten the center floor side member(CFSM) which is normally manufactured using $600{\sim}800MPa$ steel sheet, new design of the manufacturing process for CFSM using APFC980 has been proposed. To accomplish this goal, the influence of process variables such as die corner radius and die wall angle on the springback were investigated using FE-analysis. In order to insure the validity of FE-analysis, the springback results of FE-analysis was verified with prototype product.

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Multi-objective Optimization to Reduce Wrinkle & Thinning in Sheet Metal Forming of Ultra High Strength Steel (1.2GPa) (1.2GPa 강판의 판재성형에서 주름 및 성형성 향상을 위한 다중 목적함수 최적 설계)

  • Lee, Y.S.;Kwon, S.H.;Kim, H.L.;Kim, S.W.;Jung, C.Y.;Hong, S.
    • Transactions of Materials Processing
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    • v.25 no.5
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    • pp.295-300
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    • 2016
  • Recently, Ultra High Strength Steel (UHSS) sheet metal has been widely used to improve lightweight structures in the automobile industry. Because UHSS sheets have high strength but low elongation, it is difficult to control winkle and thinning for complex shaped products. The draw beads on die surface were introduced in this study to reduce wrinkle and thinning. The positions and strength values of draw beads were selected as design variables and optimized using finite element analysis. The beads positions and strength of a mold for B-pillar part were designed with the proposed optimization method. The accuracy of die design from optimization was verified by comparing with the results from 3-D scanned geometry.

The Development of Seat Track Parts Using Shape Freeze in UHSS (초고강도 소재 성형시 형상 동결을 이용한 Seat Track 부품 개발)

  • Park, Dong Hwan;Yun, Jae Jung;Moon, Hyun Duk;Lee, Tae Gil
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.26 no.1
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    • pp.59-65
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    • 2017
  • A seat track product is a car seat part that provides a base for vehicle seats. An ultra-high strength steel sheet is used to reduce the weight of vehicle body parts. However, the formability of an ultra-high strength steel sheet is poor because of its very low elongation and very high elastic deformation. For this reason, a new forming technology of an ultra-high strength steel sheet is required. The influence of spring-back of seat track parts on the shape freeze in forming processes was investigated to be solved by adjusting the appropriate tool design such as minus clearance between punch and die, and punch angle. This paper describes how to apply the spring-back prevention technique for improving shape freeze by using the ultra-high strength steel sheet with 980MPa to develop lightweight seat tract parts.

A Study on the Output and Reliability Characteristics of Ultra Barrier Film PV Module (고분자 보호 필름을 적용한 태양광 모듈의 출력 및 신뢰성에 관한 연구)

  • Lim, Jong Rok;Shin, Woo Gyun;Yoon, Hee Sang;Kim, Yong Sung;Ju, Young-Chul;Ko, Suk-Whan;Kang, Gi-Hwan;Hwang, Hye-Mi*
    • Journal of the Korean Solar Energy Society
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    • v.39 no.5
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    • pp.1-10
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    • 2019
  • Recently, the installation capacity of PV (photovoltaic) systems has been increasing not only field installation but also floating PV, farm land, BIPV/BAPV. For this reason, the new design and materials of PV module are needed. In particular, in order to apply a PV system to a building, lightweight of the PV module is essential. PV modules made of generally used texturing glass are excellent in output and reliability, but there is a limit to the weight that can be reduced. For the lightweight of the PV module, it necessary to use a film instead of a glass. However, the application of film rather than a glass may cause various problems such as decrease in photocurrent by decrease in transmittance and a increase of CTM (cell to module) loss, a degradation of the reliability, and so on. In this paper, PV modules using Ultra barrier film, which is recently a lot of interest as a substitute for a glass, its characteristic analysis and reliability test were conducted. The transmittance and UV characteristics of each material were verified, and the output of the fabricated 1 cell PV module was measured. In addition, 24 cell PV modules were fabricated at the lab-scale and its reliability tests were conducted. As a result of the experiment, the reliability characteristics of the ultra barrier film PV module were excellent, and it was confirmed that it could be used as the front material of the PV module instead of glass

Analytical evaluation and study on the springback according to the cross sectional form of 1.2GPa ultra high strength steel plate (1.2GPa급 초고강도강판의 단면 형태에 따른 스프링백에 관한 해석적 평가 및 연구)

  • Lee, Dong-Hwan;Han, Seong-Ryeol;Lee, Chun-Kyu
    • Design & Manufacturing
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    • v.13 no.4
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    • pp.17-22
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    • 2019
  • Currently, studies on weight reduction and fuel efficiency increase are the most important topics in the automotive industry and many studies are under way. Among them, weight reduction is the best way to raise fuel efficiency and solve environmental pollution and resource depletion. Materials such as aluminum, magnesium and carbon curing materials can be found in lightweight materials. Among these, research on improvement of bonding technology and manufacturing method of materials and improvement of material properties through study of ultrahigh strength steel sheet is expected to be the biggest part of material weight reduction. As the strength of the ultra hight strength steel sheet increases during forming, it is difficult to obtain the dimensional accuracy as the elastic restoring force increases compared to the hardness or high strength steel sheet. It is known that the spring back phenomenon is affected by various factors depending on the raw material and processing process. We have conducted analytical evaluations and studies to analyze the springback that occurs according to the cross-sectional shape of the ultra high tensile steel sheet.