• Title, Summary, Keyword: hybrid tube

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Bending Performance Evaluation of Aluminum-Composite Hybrid Square Tube Beams (알루미늄-복합재료 혼성 사각관 보의 굽힘 성능평가)

  • Lee, Sung-Hyuk;Choi, Nak-Sam
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.76-79
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    • 2005
  • Bending deformation and energy absorption characteristics of aluminum-composite hybrid tube beams have been analyzed for improvement in the bending performance of aluminum space frame by using experimental tests combined with theoretical and finite element analyses. Hybrid tube beams composed of glass fabric/epoxy layer wrapped around on aluminum tube were made in autoclave with the recommended curing cycle. Basic properties of aluminum material used for initial input data of the finite element simulation and theoretical analysis were obtained from the true stress-true strain curve of specimen which had bean extracted from the Al tube beam. A modified theoretical model was developed to predict the resistance to the collapse of hybrid tube beams subjected to a bending load. Theoretical moment-rotation angle curves of hybrid tube beams were in good agreement with experimental ones, which was comparable to the results obtained from finite element simulation. Hybrid tube beams strengthened by composite layer on the whole web and flange showed an excellent bending strength and energy absorption capability.

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Axial Crush and Energy Absorption Characteristics of Aluminum/GFRP Hybird Square Tubes (알루미늄/GFRP 혼성 사각튜브의 정적 압축 붕괴 및 에너지 흡수 특성)

  • 김구현;이정주;신금철
    • Transactions of the Korean Society of Automotive Engineers
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    • v.8 no.6
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    • pp.208-219
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    • 2000
  • In this study, static axial crush tests were performed with the new aluminum/GFRP hybrid tube. Glass/Epoxy prepregs were wrapped around an aluminum tube and co-cured. The failure of the hybrid tube was stable and progressive without trigger mechanism, and specific energy absorption was increased to the maximum of 33% in comparison with the aluminum tube. Effective energy absorption is possible for an inner aluminum tube because a wrapped composite tube constrains the deflection of an aluminum tube. The failure of a hybrid composite tube was stable without trigger mechanism because the inner aluminum tube could play the role of the crack initiator and controller. Mean crushing load could be calculated by modifying the plastic hinge collapse model for hybrid materials. The predicted results by this analytical model showed good agreement with the experimental results. It can be said that Aluminum/Glass-Epoxy hybrid tube is suitable for the vehicle front structure because this hybrid tube shows effective energy absorption, easy production, and simple application capability for RTM process.

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Axial crush and energy absorption characteristics of Aluminum/GERP hybrid square tube (알루미늄/GFRP 혼성 사각튜브의 정적 압축 붕괴 및 에너지 흡수 특성)

  • 김구현;이정주
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.168-171
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    • 1999
  • For the axial crushing tests of various shape of tubes, it was reported that composite tubes need trigger mechanism to avoid brittle failure. In this study, static axial crush tests were performed with the new aluminum/GFRP hybrid tubes. Glass/Epoxy prepregs were wrapped around aluminum tube and co-cured. The failure of hybrid tube was stable and progressive without trigger mechanism, and specific energy absorption was increased to maximum 34% in comparison with aluminum tube. Effective energy absorption is possible for inner aluminum tube because wrapped composite tube constrain the deflection of aluminum tube and reduce the folding length. The failure of hybrid composite tube was stable without trigger mechanism because inner aluminum tube could play the role of crack initiator and controller. Aluminum/Glass-Epoxy hybrid tube is suitable for the vehicle front structure due to effective energy absorption capability, easy production, and simple application for RTM process.

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Development of Hybrid Expander Unit for Fin Tube Heat Exchanger (핀튜브 열교환기용 전관확관 유닛 개발)

  • Roh, Geonsang;Kim, Jongnam
    • Journal of the Korean Society of Mechanical Technology
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    • v.13 no.4
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    • pp.165-168
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    • 2011
  • In this paper, the hybrid tube expander unit for fin and tube type heat exchanger are developed by means of enlarging and inserting the smooth tube with a small diameter to a finned tube having larger diameter. In other word, the tube expander tool that is easy to attach and remove from tube is developed. The hybrid tube expander unit developed in this study can move easily and enlarge the tube without fixing at tube sheet. Also, this unit has a function removing scales inside tube by replacing a tube expander ball.

The characteristics of bending collapse of aluminum/GFRP hybrid tube (알루미늄/GFRP 혼성튜브의 굽힘붕괴 특성)

  • 송민철;이정주
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.84-87
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    • 2000
  • Square tubes used for vehicle structure components have an important role on keeping its stiffness and preserving occupant safety in vehicle collision and rollover in which it experience axial collapse, bending collapse or both. Bending collapse, which absorbs kinetic energy of the impact and retains a survival space for the occupant, is a dominant failure mode in oblique collision and rollover. Thus, in this paper, the bending collapse characteristics such as the maximum bending moment and energy absorption capacity of the square tube replaced by light-weight material were evaluated and presented. The bending test of cantilever tubes which were fabricated with aluminum, GFRP and aluminum/ GFRP hybrid by co-curing process was performed. Then the maximum bending moment and the energy absorption capacity from the moment-angle curve were evaluated. Based on the test results, it was found that aluminum/ GFRP hybrid tube can show better specific energy absorption capacity compared to the pure aluminum or GFRP tube and can convert unstable collapse mode which may occur in pure GFRP tube to stable collapse mode like a aluminum tube in which plastic hinge is developed.

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MULTI-SCALE SIMULATION FOR DESIGN OF A CATALYTIC MULTI-TUBULAR REACTOR (다관식 촉매 반응기 설계를 위한 multi-scale simulation)

  • Shin Sang-Baek;Im Ye-Hoon;Ha Kyoung-Su;Urban Zbigniew;Han Sang-Phil
    • 한국전산유체공학회:학술대회논문집
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    • pp.49-53
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    • 2005
  • This paper presents a multi-scale hybrid simulation for the design of a catalytic multi-tubular reactor with high performance. The multi-tubular reactor consists of shell and a large number of tubes in which various catalytic chemical reactions occur. To consider fluid dynamics in the shell-side and kinetics in the tube-side at the same time, commercial CFD package and process simulation tool are coupled. This hybrid approach allowed us to predict many kinds of meaningful results such as tube center temperature profile, heat transfer coefficients on the tube wall, temperature rise of cooling medium, pressure drop through shell and tube side, concentration profile of each chemical species along the tube, and so on., and to achieve the optimal reactor design.

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Behavior of Hybrid Double Skin Concrete Filled Circular Steel Tube Columns

  • Kim, Jin-Kook;Kwak, Hyo-Gyoung;Kwak, Ji-Hyun
    • Steel and Composite Structures
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    • v.14 no.2
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    • pp.191-204
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    • 2013
  • A hybrid double skin concrete filled (HDSCF) circular steel tube column is proposed in this study. The yield strength of the outer steel tube is larger than 690MPa and the inner tube has less strength. In order to achieve efficiency with the high strength outer tube, a feasibility study on reducing the thickness of the tube below the specified design codes for CFTs was conducted based on an experimental approach. The experiment also took variables such as thickness of the inner tube, hollow ratio, and strength of concrete into consideration to investigate the behavior of the HDSCF column. In order to estimate the applicability of design equations for CFTs to the HDSCF column, test results from CFT and HDSCF columns with design codes were compared. It was found that the axial compressive performance of the proposed HDSCF column is equivalent to that of the conventional CFT member irrespective of design variables. Furthermore, the design equation for a circular CFT given by EC4 is applicable to estimate the ultimate strength of the HDSCF circular steel tube column.

Bending Performances and Collapse Mechanisms of Light-weight Aluminum-GERP Hybrid Square Tube Beams (경량화 알루미늄-GFRP 혼성 사각관 보의 굽힘성능 및 붕괴 메커니즘)

  • Lee, Sung-Hyuk;Kim, Hyung-Jin;Chang, Young-Wook;Choi, Nak-Sam
    • Composites Research
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    • v.20 no.3
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    • pp.8-16
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    • 2007
  • Bending collapse of light-weight square tubes used for vehicle structure components is a dominant failure mode in oblique collision and rollover of vehicles. In this paper bending performances of aluminum-GFRP hybrid tube beams were evaluated in relation with bending deformation behavior and energy absorption characteristics. Aluminum/GFRP hybrid tube beams fabricated by inserting adhesive film between prepreg and metal layer were used in the bending test. Failure mechanisms of hybrid tubes under a bending load were experimentally investigated to analyze the bending performance as a function of ply orientation and composite layer thickness. Ultimate bending moments and energy absorption capacity of hybrid tube beams were obtained from the measured load-displacement corves. It was found that aluminum/GFRP hybrid tubes could be converted to rather stable collapse mode showing excellent energy absorption capacity in comparison to the pure aluminum tube beams. In particular, the hybrid tube beam with $[0^{\circ}/90^{\circ}]s$ composite layer showed a large improvement by about 78% in energy absorption capacity and by 29% in specific energy absorption.

Design and Behavior of Validating Surge Protective Devices in Extra-low Voltage DC Power Lines (특별저전압 직류 전원회로에 유용한 서지방호장치의 설계와 특성)

  • Shim, Seo-Hyun;Lee, Bok-Hee
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.3
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    • pp.81-87
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    • 2015
  • In order to effectively protect electrical and electronic circuits which are extremely susceptible to lightning surges, multi-stage surge protection circuits are required. This paper presents the operational characteristics of the two-stage hybrid surge protection circuit in extra-low voltage DC power lines. The hybrid surge protective device consists of the gas discharge tube, transient voltage suppressor, and series inductor. The response characteristics of the proposed hybrid surge protective device to combination waves were investigated. As a result, the proposed two-stage surge protective device to combination wave provides the tight clamping level of less than 50V. The firing of the gas discharge tube to lightning surges depends on the de-coupling inductance and the rate-of-change of the current flowing through the transient voltage suppressor. The coordination between the upstream and downstream components of the hybrid surge protective device was satisfactorily achieved. The inductance of a de-coupler in surge protective circuits for low-voltage DC power lines, relative to a resistance, is sufficiently effective. The voltage drop and power loss due to the proposed surge protective device are ignored during normal operation of the systems.

Investigation on-board pulse tube refrigerator for high temperature superconducting rotor (고온 초전도 회전자 냉각을 위한 탑재형 맥동관 냉동기 연구)

  • 남중원;정상권
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • pp.316-319
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    • 2003
  • Cryogenic refrigerator system is necessary for cooling the superconducting rotor. Among the various cryogenic refrigerator systems, on-board hybrid pulse tube cryocooler is designed for cooling the superconducting rotor. Hybrid pulse tube cryocooler is composed of pulse tube cryocooler and Stirling cryocooler. This Stirling cryocooler precools the middle point of regenerator to obtain lower temperature at cold part of pulse tube cryocooler. In this paper, only Stirling cryocooler is on-boarded then rotated by motor for various rotating speeds and heat loads at cold part of Stilting cryocooler. Through this experiment the feasibility of the on-board cryocooler is investigated.

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