http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Spot Welding of Aluminum and Cast Iron by Friction Bit Joining
Michael Miles,홍성태,Coulter Woodward,정용하 한국정밀공학회 2013 International Journal of Precision Engineering and Vol.14 No.6
Dissimilar combinations of aluminum alloy A356 and grey cast iron were spot welded by friction bit joining. In order to facilitate bonding, an intermediate layer of interstitial free steel was placed between the aluminum and the cast iron. Welding development resulted in cycle times of approximately 5 seconds, and lap shear fracture loads of up to 6.8 kN.
저온 디젤 연소에서 스월비에 따른 CO 배출 및 연비 변화
국상훈(Sanghoon Kook),Paul C. Miles(Paul C. Miles),Michael Bergin(Michael Bergin),배충식(Choongsik Bae) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
Engine-out CO emission was measured over a wide range of swirl ratios and injection timings on low-temperature diesel combustion regime in a small~bore single-cylinder diesel engine. Our previous work has shown that late-cycle mixing plays an important role even in so-called dilution-controlled low-temperature combustion systems. In this study. we employ multi-dimensional numerical simulation to characterize the flow structures and their impact on CO emissions. 65% exhaust gas recirculation is simulated with additional N₂ and CO₂, The CO emission shows optimal values at swirl ratio of 2.59 and limited ranges of injection timings. The numerical simulations show that the formed CO is trapped inside bowl at high swirl of 7.12. while CO is lifted out due to an enhanced reverse squish flow with a swirl ratio of 2.59. For a lower swirl ratio of 1.44, the existence of a single, large bulk flow structure limits the mixing process. The measured fuel conversion efficiency shows maximum value at low swirl ratio. The source of the maxima is clarified by the analysis of the work conversion efficiency, combustion efficiency, and heat transfer loss. Results show heat loss plays important role in determining the fuel conversion efficiency.
Joint Strength in High Speed Friction Stir Spot Welded DP 980 Steel
Nathan Saunders,Michael Miles,Trent Hartman,Yuri Hovanski,Sung-Tae Hong,Russell Steel 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
High speed friction stir spot welding was applied to 1.2 mm thick DP 980 steel sheets under different welding conditions, using PCBNtools. The range of vertical feed rates used during welding was 2.5~102 mm per minute, while the range of spindle speeds was 2500~6000 rpm. Extended testing was carried out for five different sets of welding conditions, until tool failure. These welding conditionsresulted in vertical welding loads of 3.6~8.2 kN and lap shear tension failure loads of 8.9~11.1 kN. PCBN tools were shown, in thebest case, to provide lap shear tension failure loads at or above 9 kN for 900 spot welds, after which tool failure caused a rapid dropin joint strength. Joint strength was shown to be strongly correlated to bond area, which was measured from weld cross sections. Failure modes of the tested joints were a function of bond area and softening that occurred in the heat-affected zone.
안은영,Hrishikesh Das,홍성태,한경식,Michael Miles,이광진,박주원,한흥남 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.8
The effects of combinations of dissimilar aluminum alloys during Friction stir welding (FSW) on the process response and resultant joint properties are experimentally investigated using two dissimilar automotive structural aluminum alloys. Depending on the materials on the advancing and retreating sides of the tool travel direction during FSW, four different material combinations are considered. FSW joints without macroscopic defects are successfully fabricated for the four different material combinations. The optical microscopy results show that the macroscopic material mixing behaviors of the two dissimilar material combinations during FSW are somewhat different from each other, even though the process responses during joining are not much different. The results of the quasi-static tensile tests and EBSD analysis demonstrate that the mechanical behaviors and orientation changes of the joint during tensile deformation are affected by the material locations with respect to the tool travel direction during FSW.
김주리,안은영,Hrishikesh Das,정용하,홍성태,Michael Miles,이광진 한국정밀공학회 2017 International Journal of Precision Engineering and Vol.18 No.3
The effects of tool geometry and process parameters on the mechanical properties of friction stir spot welded (FSSW) dissimilar aluminum alloys are experimentally investigated. Two tools with different shoulder profiles, concave and convex, were considered. Two typical automotive aluminum alloys were selected for FSSW, thus resulting in two different material combinations for each shoulder profile. The experimental results showed that the two shoulder profiles caused significant differences in the axial force, the mixing of materials, and the mechanical properties of the joint. The sensitivity of joint strength to the variation of the tool rotation speed and the plunge speed was also quite dependent on the shoulder profile. The experimental result shows that the change of joint strength can be quite significant.
Hossain, Md. Abu Mowazzem,Hasan, Md. Tariqul,Hong, Sung-Tae,Miles, Michael,Cho, Hoon-Hwe,Han, Heung Nam Hindawi Limited 2014 Advances In Materials Science And Engineering Vol.2014 No.-
<P>Mechanical properties and failure behaviors of friction stir spot welded (FSSW) joints of two dissimilar ferrous alloys, cold-rolled carbon steel (SPCC) and 409L stainless steel (SUS 409L), are investigated under opening-dominant combined loads. The texture of dissimilar FSSW joints depends on the upper sheet material. The failure contours for the FSSW joints under combined loads are constructed in terms of the axial load and shear load by modifying existing failure criteria for resistance spot welds. The shape of the failure contour also depends on the upper sheet material. The failure contours are nearly elliptic in shape when the upper sheet is SPCC and are relatively straight lines when the upper sheet is SUS 409L.</P>
Friction Stir Spot Welded Joints of 409L Stainless Steels Fabricated by a Convex Shoulder Tool
Md. Abu Mowazzem Hossain,Md. Tariqul Hasan,Sung-Tae Hong,Michael Miles,Hoon-Hwe Cho,한흥남 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.6
Spot joints of ferritic 409L stainless steel are successfully fabricated by friction stir spot welding (FSSW) using a convex shoulder tool. The welding process, microstructure and failure of the FSSW joint are investigated experimentally. During the FSSW process, the Z-force history shows significant variations depending on the contact phenomena between the tool and the joined sheets, while the Z-torque history shows a rather steady increase without pronounced changes in the trend until the initiation of dwelling. Electron back-scatter diffraction suggests that both continuous dynamic recrystallization and recovery occurred in the stir zone during the FSSW process. Observation of the FSSW joint that failed under the given lap shear load shows that the cracks, which are the result of the interfaces between the upper and lower sheets, propagated into the weld along the interfacial surfaces, after which a necking/shear failure occurred. Finally, the rupture of the joint, which was initiated by the necking/shear failure, propagated along the circumference of the weld.