• Title/Summary/Keyword: Al tube

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Solid State Joining Processes for Dissimilar Joints of Mg/Al Alloys (고상접합을 이용한 Al/Mg 합금의 이종 용접)

  • Kim, Heung-Ju;Kim, Wook-Seong;Chun, Chang-Keun;Chang, Woong-Seong
    • Proceedings of the KWS Conference
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    • 2009.11a
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    • pp.41-41
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    • 2009
  • To evaluate the applicability of dissimilar joining between Mg and Al alloys in automobile manufacturing process, solid state joining processes such as magnetic pulse welding(MPW), friction stir welding(FSW) and friction spot joining(FSJ) were attempted successfully. MPW process has been concentrated mainly on round section tube to tube and tube to bar welds. AZ31 Mg alloy has been successfully welded to pure Al A1070 as well as to Al alloy A3003. While, for friction stir welding of dissimilar sheet joints, AZ31B/A6061 with the thickness of 2mm were used and a square butt joint with a good quality was obtained at the conditions of 0.8mm/sec of travel speed and tool rotation speed of 850rpm. The maximum tensile strength of 179 MPa, which was about 80 % of the Mg base metal tensile strength, has been obtained. Finally, friction spot joining was attempted to make a dissimilar lap joint between AZ31(0.8mm) and A6061(1mm), while the joint exhibited the same level of tensile shear strength as that of similar Mg joint.

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A Study for Evaporation Heat Transfer Characteristic of R22/Rl14 Refrigerant Mixtures in a Horizontal Tube (수평증발관내 R22/R114 혼합냉매의 열전달 특성에 관한 연구)

  • 윤치한;이종인;하옥남
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.5
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    • pp.502-510
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    • 2000
  • Evaporation heat transfer characteristics were studied in a horizontal tube using R22/R114 non-azotropic refrigerant mixture. the heat transfer coefficient was high in the upper part for pure refrigerants, and heat transfer coefficient was low in the lower part for refrigerant mixtures. In the low quality region where nucleate boiling was dominant, the average heat transfer coefficient was low. In the region where forced convection was dominant, heat transfer coefficient was high. Results show that the heat transfer coefficient for pure refrigerants obtained by experiments were lower than those of Yoshida et al. but agreed well with Jung et al., and Chen et al. data. But the heat transfer coefficients for refrigerant mixtures were lower about 20% than those predicted by the equation for pure refrigerant.

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Investigation of Forming Stabilities Criteria in Hot Backward Extrusion of Ti-6Al-4V (Ti-6Al-4V합금의 열간 후방압출에 대한 성형 안정성 평가모델의 고찰)

  • Yeom Jong-Taek;Park Nho-Kwang;Lee You-Hwan;Shin Tae-Jin;Hwang Sang-Mu;Hong Sung-Suk;Shim In-Ok;Lee Chong-Soo
    • Journal of the Korea Institute of Military Science and Technology
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    • v.7 no.3 s.18
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    • pp.84-92
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    • 2004
  • The metal forming behavior of Ti-6Al-4V tube during hot backward extrusion was investigated with various forming stabilities or instabilities criteria. that is, Ziegler's instability criterion, dynamic materials model(DMM) stability criteria and Rao's instability criterion. These approaches also were coupled to the internal variables generated from FE simulation. In order to validate the reliabilities of three criteria, hot backward extrusions for Ti-6Al-4V tube making were carried out with different backward extrusion designs. The useful model for predicting the forming defects was suggested through the comparison between experimental observations and simulation results.

Viscoplastic analysis of thin-walled tubes under cyclic bending

  • Pan, Wen-Fung;Hsu, Chien-Min
    • Structural Engineering and Mechanics
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    • v.7 no.5
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    • pp.457-471
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    • 1999
  • In this paper, different curvature-rates are controlled to highlight the characteristic of viscoplastic response in cyclic bending tests. The curvature-ovalization apparatus, which was designed by Pan et al. (1998), is used for conducting the curvature-controlled experiments on thin-walled tubular specimens for AISI 304 stainless steel under cyclic bending. The results reveals that the faster the curvature-rate implies, the fast degree of hardening of the metal tube. However, the ovalization of the tube cross-section increases when the curvature-rate increases.

Performance of lightweight aggregate and self-compacted concrete-filled steel tube columns

  • AL-Eliwi, Baraa J.M.;Ekmekyapar, Talha;Faraj, Radhwan H.;Gogus, M. Tolga;AL-Shaar, Ahmed A.M.
    • Steel and Composite Structures
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    • v.25 no.3
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    • pp.299-314
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    • 2017
  • The aim of this paper is to investigate the performance of Lightweight Aggregate Concrete Filled Steel Tube (LWCFST) columns experimentally and compare to the behavior of Self-Compacted Concrete Filled Steel Tube (SCCFST) columns under axial loading. Four different L/D ratios and three D/t ratios were used in the experimental program to delve into the compression behaviours. Compressive strength of the LWC and SCC are 33.47 MPa and 39.71 MPa, respectively. Compressive loading versus end shortening curves and the failure mode of sixteen specimens were compared and discussed. The design specification formulations of AIJ 2001, AISC 360-16, and EC4 were also assessed against test results to underline the performance of specification methods in predicting the compression capacity of LWCFST and SCCFST columns. Based on the behaviour of the SCCFST columns, LWCFST columns exhibited different performances, especially in ductility and failure mode. The nature of the utilized lightweight aggregate led to local buckling mode to be dominant in LWCFST columns, even the long LWCFST specimens suffered from this behaviour. While with the SCCFST specimens the global buckling governed the failure mode of long specimens without any loss in capacity. Considering a wide range of column geometries (short, medium and long columns), this paper extends the current knowledge in composite construction by examining the potential of two promising and innovative structural concrete types in CFST applications.

Assessment of stress-strain model for UHPC confined by steel tube stub columns

  • Hoang, An Le;Fehling, Ekkehard
    • Structural Engineering and Mechanics
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    • v.63 no.3
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    • pp.371-384
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    • 2017
  • Ultra high performance concrete (UHPC) has recently been applied as an alternative to conventional concrete in construction due to its extremely high compressive and tensile strength, and enhanced durability. However, up to date, there has been insufficient information regarding the confinement behavior of UHPC columns. Therefore, this study aims to perform an assessment of axial stress-strain model for UHPC confined by circular steel tube stub columns. The equations for calculating the confined peak stress and its corresponding strain of confined concrete in existing models suggested by Johansson (2002), Sakino et al. (2004), Han et al. (2005), Hatzigeorgiou (2008) were modified based on the regression analysis of test results in Schneider (2006) in order to increase the prediction accuracy for the case of confined UHPC. Furthermore, a new axial stress-strain model for confined UHPC was developed. To examine the suitability of the modified models and the proposed model for confined UHPC, axial stress-strain curves derived from the proposed models were compared with those obtained from previous test results. After validating the proposed model, an extensive parametric study was undertaken to investigate the effects of diameter-to-thickness ratio, steel yield strength and concrete compressive strength on the complete axial stress-strain curves, the strength and strain enhancement of UHPC confined by circular steel tube stub columns.

Process Analysis and Die Design for Al3003 Condenser Tube Extrusion with 12 Cell (Al3003 12셀 컨덴서 튜브의 압출을 위한 공정해석 및 금형설계)

  • Lee, Sang-Ho;Lee, Jung-Min;Jo, Hyung-Ho;Jo, Hoon;Kim, Mun-Bae;Kim, Byung-Min
    • Journal of the Korean Society for Precision Engineering
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    • v.24 no.11
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    • pp.44-51
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    • 2007
  • Condenser tubes are mainly produced by precision extrusion with a porthole die and are used in the flow pass of refrigerant cooling systems in automobiles. The recent technical trend of condenser tube requires the tube to be of more multi cellizing, high strength and small size, and to increase the heat transfer area and heat efficiency. Hence, this paper is shown that the results of FE-simulation are in good agreement with the experimental ones. Finally, the extrusion die shape is proposed through analysis of FE-simulation and performance of trial extrusion. Chamber shape dimension and initial temperatures of die is adjusted analysis results. And the possibility of extrusion is estimated that forming load, welding pressure and stress analysis of die in this paper. The validity of simulated results was verified into extrusion experiments on the condenser tubes.

FE Simulation of Extrusion Process for Al Multi Cell Tube According to the Changes of the Porthole Shape (포트홀 형상 변화를 고려한 Al 멀티셀 튜브 압출공정 해석)

  • Lee Jung Min;Kim Dong Hwan;Ho Jo Hyung;Kim Byung Min
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.8 s.239
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    • pp.1146-1152
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    • 2005
  • Recently, multi cell tube which is used for a cooling system of automobiles is mainly manufactured by the conform extrusion but this method is inferior as compared with direct extrusion in productivity per the unit time and in the equipment investment. Therefore, it is essential for the conversion of direct extrusion with porthole die. The direct extrusion with porthole die can produce multi cell tube which has the competitive power in costs and qualities compared with the existing conform extrusion. This study is designed to evaluate metal flow, welding pressure, extrusion load, tendency of mandrel deflection that is affected by variation of porthole shape in porthole die. Estimation is carried out using finite element method under the non-steady state. Also this study was examined into the cause of mandrel fracture through investigating elastic deformation of mandrel during the extrusion.

Development of Direct Extrusion Process on Al 1050 Condenser Tube by using Porthole Die (포트홀 다이를 이용한 Al1050 컨덴서 튜브의 직접압출공정 기술 개발)

  • 이정민;김병민;강충길;조형호
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.7
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    • pp.53-61
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    • 2004
  • Condenser tube which is used for a cooling system of automobiles is mainly manufactured by conform extrusion. However, direct extrusion using porthole die in comparison with conform extrusion has many advantages such as improvement of productivity, reduction of production cost etc. In general, the porthole die extrusion process is useful for manufacturing long tubes with hollow sections and consists of three stages(dividing, welding and forming stages). Especially, Porthole die for producing condenser tube is very complex. Thus, in order to obtain the detailed mechanics, to assist in the design of proper die shapes and sizes, and to improve the quality of products, porthole die extrusion should be analyzed in as non-steady state as possible. This paper describes FE analysis of non-steady state porthole die extrusion for producing condenser tube with multi-hole through 3D simulation in the non-steady state during the entire process to evaluate detailed metal flow, temperature distribution, welding pressure and extrusion load. Also to validate FE simulation of porthole die extrusion, a comparison of simulation and experiment results was presented in this paper.

A Study on the Local Buckling Collapse Behavior of an Aluminum Square Tube Beam under a Bending Load (굽힘하중을 받는 알루미늄 사각관 보의 국부적 좌굴붕괴 거동에 관한 연구)

  • Lee, Sung-Hyuk;Choi, Nak-Sam
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.12
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    • pp.2011-2018
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    • 2003
  • To analyze the bending collapse behavior of an aluminum square tube beam under a bending load, a finite element simulation for the four-point bending test has been performed. Using an aluminum tube beam specimen partly inserted with two steel bars, the local buckling deformation near the center of the tube beam was induced. The maximum bending load and the bending collapse behavior obtained from the numerical simulation were in good agreement with experimental results. Using a combination of the four-point bending test and its finite element simulation, analysis of the local buckling and the accompanied bending collapse behavior of aluminum tube beam could be quantitative accomplished.