Abstract: Explosive welding of a thin magnesium plate onto some metal plates was performed by
using underwater explosive welding technique developed by some of the authors. The experimental
results show that the wavy interface which is typically found in the well-bonded clad was observed.
The welding condition is discussed using the welding window based on the numerically simulated
results using AUTODYN-2D code.
Abstract: The paper describes a numerically simulated result for the explosive welding using
reflected underwater shock wave. Through the numerical simulation, the effective use of reflected
underwater shock wave was clearly suggested and the method to improve the assembly was
Abstract: A new method has been developed to generate an extremely high impulsive pressure by
using a metal jet that is discharged when a metal collides with another metal. The high pressure is
used to synthesize a new material. When a metal plate was accelerated by the detonation of an
explosive, it collides with the concentric circle of the conic surface of a conical concave metal block
metal jets are discharged from all parts on the concentric circle. The metal jets fly toward the center
while converging and collide with each other at the central axis. Because those collide at high-speed
pressure becomes extremely high. The flight direction of the converged metal jet changes
downward. The metal jet collides with the bottom of the block. A large hole is formed inside the
bottom. The formation process of the hole was examined by the observation of the section of the
block. A specimen powder that was rubbed to the conic surface is discharged with the metal jet and
become the high pressure. The specimen powder is synthesized to a different material. The
synthesized material is held inside the formed hole. The existence of cBN was confirmed by the
X-ray diffraction of the synthesized material, in the case that BN was used as the specimen powder.
Similarly, the existence of diamond was confirmed in the case of graphite powder.
Abstract: In the research center for advances in impact engineering established in Sojo university, advanced
materials have been synthesized by using shock wave and their microstructure has been investigated.
An extremely high shock pressure and a dynamic hot compaction technique were developed, and
the synthesis of the advanced materials and composites was succeeded. Transmission electron
microscopy observations revealed unique microstructures of such materials obtained by our original
Abstract: To increase largely the performance of shaped charge, it is required to generate detonation velocity
much higher than CJ velocity or detonation pressure much higher than CJ pressure of existing high
explosives. One solution is the application of overdriven detonation phenomena. In this study, the
effects of overdriven detonation in tungsten loaded high density explosive on the performance of
shaped charge were demonstrated by experiments and numerical simulation. Sample shaped charge
was composed of the inner layer tungsten loaded high density PBX and outer layer high velocity
PBX. Concentration of tungsten powder in high density PBX was varied from 20 to 60% in mass.
The pressure of overdriven detonation in inner layer PBX was measured by PMMA gauge, and was
shown to be higher than 50GPa. The experimental results showed that the initial jet velocity and jet
penetration velocity in target plates were largely increased by the effects of the overdriven detonation
in tungsten loaded high density PBX.
Abstract: The tungsten carbide - cobalt, (WC-Co) powder is compacted and bonded to on a stainless steel
(SUS304) rod by using explosives. In this research, the experiments are conducted using two
methods. They are the method of making the pressure of the explosive act directly on the powder and
the method of explosively driving a metal pipe with high speed to create high pressure acting on
powder. Crack free bulk material was recovered. Heat-treatment was performed on the recovered
sample. After heat treatment, the value of hardness was increased compared with commercial
Abstract: In order to achieve an optimal design of shock compaction device, various designs of parts
are attempted. For the height of water container that creates an underwater shock wave and a reflected
wave, a characteristic of underwater shock wave is evaluated by means of numerical analysis. It is
found that the underwater shock wave and the reflected wave became one wave with higher shock
pressure in the case of water container (height 21.5 mm). Also, the evaluation for a powder container
is experimentally tried in consideration of reuse.
Abstract: A shock compaction method using an underwater shockwave is used to consolidate the
Cu/graphite and Ni/graphite composites. The copper powder (particle size < 45 m) and nickel
powder (particle size < 150 m) were respectively mixed with the graphite powder (particle size <
45 m, purity 99.9%). The propagation phenomenon of underwater shock wave is studied by means
of numerical analysis (LS-DYNA 3D) in terms of the magnitude and distribution of shock pressure
impinged on the powder surface. The shock pressure of underwater shock wave obtained from
shock compaction device is approximately 16 GPa. To make a big size material (ø30mm), we
changed the inner size of powder container from ø10 mm to ø30 mm. We confirmed that the
consolidation possibility of the big size composite materials (Cu/graphite, Ni/graphite) by the shock
compaction method using underwater shock wave.
Abstract: In this study, effects of high pulse current (current density :>103 A/cm2, applied time: 15 s)
on microstructure of magnesium alloys were investigated. A mild steel was also employed as
comparison material. Refinement of microstructure by electropulsing was observed in Mg-3B2O3 and
mild steel and micro-Vickers hardness of these alloys were increased by modification of
Abstract: The results of experiments with shock – loading of graphite bar by sliding detonation wave
of HE are presented in this paper. It were revealed the nano – sized onions at the SEM investigation in
the preserved sample of Graphite. The estimation of the values of pressures of shock – loading
permits to assume that the observed structures were formed directly by solid – solid transformation.