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Optimization of Process Parameters in Explosive Cladding of Mild Steel and Aluminum
Raghukandan, K.,Hokamoto, K.,Manikandan, P. 대한금속재료학회 2004 METALS AND MATERIALS International Vol.10 No.2
Explosive cladding is best known for its capability to join a wide variety of both similar and dissimilar combinations of metals that cannot be joined by other conventional metal joining techniques. An attempt has been made to optimize the tensile and shear strengths of an explosive clad interface using fuzzy logic and genetic algorithm. The parameters considered for this study include flyer plate thickness, loading ratio, angle of inclination, and stand off distance. The experimental data was trained and simulated using fuzzy logic and the optimization of process parameters was performed using genetic algorithm. The optimized process parameters were validated using experimental results.
Fujita, Masahiro,Mochihara, Minoru,Hokamoto, Kazuyuki 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.4
An experimental technique to analyze a plastic deformation process inside material can effectively employed for a plate made by multilayered explosive welding. The formation of very fine and uniform waves, generated at each welded interface about 10 s of micrometers, helps to identify the inside deformation process. Work-hardened and annealed copper plates are used for identifying the motion of the material, especially in the horizontal direction between the punch and the die in shearing.
Metallic Glass Formation at the Interface of Explosively Welded Nb and Stainless Steel
I. A. Bataev,K. Hokamoto,H. Keno,A. A. Bataev,I. A. Balagansky,A. V. Vinogradov 대한금속·재료학회 2015 METALS AND MATERIALS International Vol.21 No.4
The interface between explosively welded niobium and stainless steel SUS 304 was studied using scanning electron microscopy, transmission electron microscopy and energy dispersive X-Ray spectroscopy. The wavy interface along which vortex zones were located was observed. The vortex zones formed due to the mixing of materials typically had amorphous structure. Inoue’s criteria of glass formation were used to explain this result. The effect of the composition, cooling rate and pressure on the glass formation are discussed. The conditions of deformation, heating, and cooling as well as shockwaves propagation were numerically simulated. We show that the conditions of vortex zone formation resemble the conditions of rapid solidification processes. In contrast to the "classical" methods of rapid solidification of melt, the conditions of metastable phase formation during explosive welding are significantly complicated by the fluctuations of composition and pressure. Possible metastable structures formation at the interface of some common explosively joined materials is predicted.
Position and Attitude Feedback Controller of a Planar Satellite with Two Thrusters
Takashi Matsuno,Shinji Hokamoto 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
This paper proposes a feedback control method for the in-plane motion of a satellite equipped with two thrusters, whose force directions are fixed to the satellite. The satellite’s equations of motion have second-order nonho-lonomic constraints. This paper utilizes an invariant manifold and develops a feedback controller based on the Lyapu-nov’s second method. The developed controller can control the satellite’s state composed of six components for the po-sition and attitude angle by two thruster systems. Furthermore, the controller has robustness for the system’s modeling errors. Some simulations results are shown to demonstrate the effectiveness of the developed controller.
Shearing of a Metal Plate Using Underwater Shock Wave and the Mechanism of Its Deformation Process
Fujita, Masahiro,Mochihara, Minoru,Hokamoto, Kazuyuki 대한금속재료학회(대한금속학회) 1998 METALS AND MATERIALS International Vol.4 No.4
A shearing process of a metal plate by an impulsive pressure generated by underwater explosion was numerically simulated, and the analytical result was compared with some experimental results. The features of the deformation and the shearing process were discussed by considering the fracture condition.
Mechanical Milling and Synthesis of Mg-SiC Composites Using Underwater Shock Consolidation
A. Nayeem Faruqui,P. Manikandan,T. Sato,Y. Mitsuno,K. Hokamoto 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.1
In this work, mechanical milling of magnesium with SiC particles with variation of parameters, such as ball-to-powder ratio, milling speed, milling time, and process controlling agent (PCA), is reported. Milling was also conducted without using PCA to explore its role on the mechanical milling process. Milling was performed in a planetary ball mill. The results show that a uniform distribution of the reinforcement, good particle yield, and particle size reduction can be achieved by controlling the parameters. The milling powders were compacted using the underwater shock wave generated by the detonation of an explosive. The samples were characterized by XRD, scanning electron microscopy, and microhardness testing. Microstructural charac-terization revealed a well flown magnesium matrix enveloping reasonably well dispersed SiC particles. The results of microhardness testing reveal an increase in the hardness of the composite.
Wada, Naoyuki,Kim, Chang-Hwan,Yoh, Jack J.,Hamashima, Hideki,Hokamoto, Kazuyuki The Japan Institute of Metals 2012 Materials Transactions Vol.53 No.1
<P>An experimental method to synthesize titanium dioxide (TiO<SUB>2</SUB>) using high-power laser in water was performed. A high-power Nd:YAG pulsed laser was used for the synthesis, with the laser energy fixed at 1 J/pulse. This laser was focused on a titanium wire set in water. This investigation recovered nano-sized anatase phase titanium dioxide with well crystallized structure. Pulsed bubbles generated in the water were confirmed by optical measurement, and their collapse may have induced high pressures and temperatures. The bubbles generated was approximately spherical in shape, with an estimated maximum size of 3.7 mm generated about 200 µs later after focusing the laser. Recovered powders were confirmed as single anatase phase titanium dioxide by XRD analysis. Effects of bubbles on synthesis and crystallization are also suggested.</P>
Masatoshi Nishi,Masaki Oshita,Miran Ulbin,Matej Vesenjak,Zoran Ren,Kazuyuki Hokamoto 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.5
The explosive compaction fabrication process of cylindrical uni-directional porous copper, consisting of an outer pipecompletely fi lled with smaller inner pipes, was investigated by experimental and computational simulations to analyzeand optimize the fabrication process conditions. The computational simulations were carried out using a two-dimensionalmodel, mimicking the transverse cross-section of fabricated specimens. The computational simulation results revealed thatthe velocity of the outer pipe, which cannot be experimentally measured, was insuffi cient for explosive welding and that thewalls of the inner pipes had the potential to fail depending on their initial positioning and thickness.
Synthesis of TiCx Powder via the Underwater Explosion of an Explosive
Shigeru Tanaka,Ivan Bataev,Hideki Hamashima,Akihiko Tsurui,Kazuyuki Hokamoto 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6
In this study, a novel approach to the explosive synthesis of titanium carbide (TiC) is discussed. Nonstoichiometric TiCxpowder was produced via the underwater explosion of a Ti powder encapsulated within a spherical explosive charge. Theexplosion process, bubble formation, and synthesis process were visualized using high-speed camera imaging. It was concludedthat synthesis occurred within the detonation gas during the first expansion/contraction cycle of the bubble, whichwas accompanied by a strong emission of light. The recovered powders were studied using scanning electron microscopyand X-ray diffraction. Submicron particles were generated during the explosion. An increase in the carbon content of thestarting powder resulted in an increase in the carbon content of the final product. No oxide byproducts were observed withinthe recovered powders.