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Kotera, Hidetoshi,Sawada, Muneo,Shima, Susumu 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.3
Numerical method based on the Cosserat continuum theory is proposed for simulating behavior of a magnetic powder in an applied magnetic field. The Maxwell stress is induced in the magnetic powder. During powder forming process in the magnetic field, the magnetic particles are thus rotated and transferred by both mechanical and magnetic interaction. To simulate such powder behavior, we formulate a finite element equation considering Maxwell stress based on the Cosserat continuum theory of compressible plasticity. The powder behavior with magnetic alignment during compaction in magnetic field is simulated by the proposed method and the effect of couple-stress on the powder behaviour is discussed.
Development of Incremental Deep Drawing Process
Kotera, Hidetoshi,Shima, Susumu,Kamitani, Kei,Bando, Toshimitsu 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.3
This paper deals with development of an incremental deep drawing process. On a newly developed incremental deep drawing set-up, the aluminium sheets are formed; the forming is carried out by deep-drawing the blank as in the conventional method but incrementally. Fractures at the punch or die comer in the blank may or may not occur depending on the conditions; the process parameters involved are punch size, punch corner radius, increment in punch displacement, blank holding force or pressure, etc. It is thus shown that different shapes are formed by one set of common tools. It is thereby confirmed that incremental deep drawing is possible without using a particular tool set for a particular shape.
Isaku Kanno,Hidetoshi Kotera,Kiyotaka Wasa,Ryouichi Takayama,Takeshi Kamada,Toshiyuki Matsunaga 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV
Compositional dependence of crystallographic structure of the epitaxial Pb(Zr,Ti)O3 (PZT) lms was investigated. The c-axis oriented PZT lms with Zr/Ti ratio ranging from 10/90 to 70/30 were epitaxially grown on (100)Pt/(100)MgO substrates using rf-sputtering. Four-circle x-ray diraction measurements revealed that the PZT lms exhibited anomalous crystalline structure which was considerably dierent from the phase diagram of bulk PZT. In particular, the PZT lms showed tetragonal structure even with the Zr/Ti composition above 53/47 and rhombohedral phase could not be identied even for the PZT lms of 70/30. The lattice constants of the PZT lms were independent of the lm thickness. The sputtering process accompanies non-thermal equilibrium reactions with the bombardment of the energetic sputtered particles to the growing lms and might induce isotropic internal stress across the lms. The anomalous crystalline characteristics are attributed to the sputter-induced stress of the PZT lms.
천두만,안성훈,최정오,이선영,Isaku Kanno,Hidetoshi Kotera 한국정밀공학회 2012 International Journal of Precision Engineering and Vol.13 No.7
With increasing concerns of environmental issues in manufacturing process, energy efficient and waste free manufacturing processes have been widely studied. In the field of nano/micro manufacturing, many research results of direct writing processes such as ink jet printing, gravure printing, and rapid prototyping processes have been reported to remove wasteproducing conventional lift-off process for patterning. In addition, the use of toxic solvents such as acetone, toluene, xylene and so on has been decreased. At the same time, energy efficiency becomes one of environmental issues in manufacturing process. In this research, Nano particle deposition system (NPDS), a dry spray deposition process for fabrication of meta and ceramic direct patterning at room temperature, was introduced according to the environmental aspects. In previous studies, NPDS has shown the feasibility of the depositions of metals such as Sn and Ni, and the depositions of ceramics such as Al2O3, and TiO2 by spraying powders under low vacuum condition. The advantages of NPDS are 1) solvent free dry deposition process, 2) relatively low energy consumption with room temperature and low vacuum process condition, and 3)direct patterning process. The energy consumption in NPDS was briefly compared with similar processes including aerosol deposition and cold spray. The direct patterning results with 200μm width line pattern using micro-nozzle were fabricated without any post-processes. These results confirmed NPDS can become a solvent-free energy efficient direct patterning process for metals and ceramics.