ENGINEERING NEWS IN BRIEF

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                  ENGINEERING NEWS IN BRIEF
                        E-Mail Newsletter

                               No.41
             Issued by the Asian TOP Panel, May 2005

           The Chinese Mechanical Engineering Society (CMES)
           The Institution of Engineers, Indonesia (PII)
           The Japan Society of Mechanical Engineers (JSME)
           The Korean Society of Mechanical Engineers (KSME)

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    According to the agreement made in the 2nd Asian TOP Panel Meeting,
the ENGINEERING NEWS IN BRIEF (E-mail newsletter) has now been edited
by the KSME for the year 2005.

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[Contents]

(1) Research on Stability of Periodic Motion of Gear Systems (Source: CMES)
(2) Design of Weld Seam Tracking Control System with DSP (Source: CMES)
(3) Study on the Material Removal Mechanism in Grinding Nanostructured Al2 O3/13TiO2 Coatings (Source: CMES)
(4) Efforts toward Development of Domestic Small-Sized Aircraft at Institute of Technology and Aeronautics (ISTA) of Japan Aerospace Exploration Agency (JAXA) (Source: JSME)
(5) Application of Superplasticity in Ceramic Materials (Source: JSME)
(6) Molecular Dynamics Simulation of Deformation of Polymer Resist in Nanoimprint Lithography (Source : KSME)

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(1) Research on Stability of Periodic Motion of Gear Systems (Source: CMES)

Prof. Gao Zhiying Northwestern Polytechnical University

For the dynamic model of strongly nonlinear gear systems with backlash, the stability of periodic motion was studied by numerical methods when the system parameters and the initial conditions were changed. Based on the Floquet bifurcation theory, the predict- correct method was used to discuss the stability of periodic solutions with changing the parameters, and the parameter values of bifurcation points were obtained accurately. The attraction domains of periodic attractors are obtained by using the cell mapping method, and the stability factor is introduced to quantificationally analyze the stability of periodic motion with changing the initial conditions. According to the research results, the parameters and the initial conditions can be properly selected, and the foundation will be laid for analysis of nonlinear dynamic behavior and design of the gear systems.

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(2) Design of Weld Seam Tracking Control System with DSP (Source: CMES)

Prof. Cao Jianshu Beijing Institute of Petrol Chemical Technology

Based on TMS320LF2407, a micro computer based weld seam tracking control system without rail used for multiple - layer welds was designed. The working principle, design of the program and hardware of control system were described in detail. A robot was directly attached on the surfaces of spherical tanks with its flexible magnetic wheel device, so as to realize the all - position walking and welding without rail. The CCD real time tracing system of the robot could make the welding gun repeatedly track all position and multi layer seams. The welding tests show that the welding robot can make all position and multiple layer welds with high tracking accuracy, excellent quality and reliable behavior.

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(3) Study on the Material Removal Mechanism in Grinding Nanostructured Al2 O3/13TiO2 Coatings (Source: CMES)

Prof. Deng Zhaohui Hunan University

Prof. Deng Zhaohui , Prof. Zhang Bi and Prof. Sun Zongyu made a parallel experimental investigations of the grinding forces, grinding force ratio, specific grinding energy, surface roughness, the ground surface/subsurface of nanostructured Al2 O3/13TiO2 coatings with an SEM so as to reveal the material removal mechanism of precision grinding of n- Al2 O3/13TiO2 coatings. It is found that the dominant material removal mechanism in precision grinding of n- Al2 O3/13TiO2 coatings is as brittle fracture including chipping and crushing which is added with material pulverization and micro plastic deformation under almost all grinding conditions.

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(4) Efforts toward Development of Domestic Small-Sized Aircraft at Institute of Technology and Aeronautics (ISTA) of Japan Aerospace Exploration Agency (JAXA) (Source: JSME)

Jiro Nakamichi, Japan Aerospace Exploration Agency (JAXA)

ISTA has been making progress of research and development of a domestic small-sized aircraft with high performance responding to the social requirements.
A five-year project was initiated from May 2003 (Project name: Research and development of high performance small aircraft with environmental compatibility), in which Mitsubishi Heavy Industry Inc., the main contractor, will develop a domestic small-sized transport.
It is the first time in the last four decades since the development of YS-11 that Japan develops a new domestic commercial aircraft.
ISTA is involved in the R&D of the new aircraft, and promotes the technical corporation and the common usage of the large research facilities such as large wind tunnel, flight simulator and super computer that ISTA has. Furthermore, in order to improve the international competitive power of the aircraft manufacturers in Japan, ISTA flexibly meets requirements of the industries through the research on advanced technologies including aerodynmics, computational fluid dynamics(CFD) , structures and materials , and flight operation system, that facilitate realization of high performance domestic aircraft.

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(5) Application of Superplasticity in Ceramic Materials (Source : JSME)

Yoshinobu Motohashi, Ibaraki University

The source powder of superplastic ceramics is very effective as interlayer for joining ceramic materials. This technique i.e., a sinter bonding method, possesses advantages such as that (1) no careful polishing to the surfaces to be bonded is necessary, and it can also apply to the surfaces with curvatures, (2) the excellent resistance to heat and corrosion at high temperatures is anticipated for the joint.
The sinter-bonding method for a typical structural ceramic, Si3N4, using 3Y-ZrO2/Al2O3 composites powder as an interlayer is shown as an example. During the process of the sinter-bonding, the sintering of the inserted powder as well as the bonding of the interfaces, Si3N4/ inserted powder /Si3N4, progressed simultaneously. Since superplasticity in the 3Y-ZrO2/AlO3 composites can arise after, even during, the sintering under proper bonding temperature and stress conditions, the surface roughness of the Si3N4 can be filled up mainly by the material flow of the interlayer even though the surfaces are uneven. The sinter-bonding was completed at temperatures ranging from 1573 to 1813 K with bonding stresses ranging from 4 to 10 MPa, at which superplastic flow of the inserted material would arise, while the Si3N4 showed no permanent deformation. The bonded Si3N4 specimens showed bending strengths of more than 300MPa at room temperature.

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(6) Molecular Dynamics Simulation of Deformation of Polymer Resist in Nanoimprint Lithography (Source : KSME)

Interesting molecular dynamics simulation was recently reported in the Transactions of KSME (Vol. 29, no. 6) by KAIST researchers for modeling nanoimprint lithography in which a stamp with patterns is pressed onto amorphous poly-(methylmethacrylate) (PMMA) surface. Force fields including bond, angle, torsion, inversion, van der Waals and electrostatic potential were used to describe the intermolecular and intramolecular force of PMMA molecules and stamp. Periodic boundary condition was used in horizontal direction and Nose-Hoover thermostat was used to control the system temperature. The adhesion forces between stamp and polymer were calculated and the mechanism of deformation was investigated. The effects of the adhesion and friction forces on the polymer deformation are reported and these results would be helpful to analyze the pattern transfer in nanoimprint lithography. The mechanism of polymer deformation was also investigated by means of inspecting the indentation process, molecular configurational properties, and molecular configurational energies.

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Editor : Professor Mansoo Choi of Seoul National University,
           Director of General Affairs, KSME
           ksme@ksme.or.kr