Metal Pipe Forming Using Underwater Shock Wave

2002 ◽  
Author(s):  
Hirofumi Iyama ◽  
K. Raghukandan ◽  
Shiro Nagano ◽  
Satoshi Muramoto ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
Cross Section ◽  
Underwater Explosion ◽  
Underwater Shock Wave ◽  
Mechanical Parts ◽  
Metal Pipe ◽  
Metal Pipes ◽  
Underwater Shock ◽  
Set Up ◽  
Oval Shape

Recently, many metal pipes have been manufactured and used as various mechanical parts. Cross section of these parts has circular and oval shape. And then, a lot of kinds, but a small quantity production of these metal pipe increases. However, commonly, very expensive metal die are used in that case. Therefore, we considered the metal pipe forming method so that we can obtain the required deformation shape of metal pipes using the underwater shock wave generated by underwater explosion of explosive. We did some experiments of the metal pipe forming by that method. We used detonating cord as the explosive. The metal pipe and explosive was submerged into water and the detonating cord was detonated by electric detonator. We made some experiments by changing the explosive set-up position and inside the metal pipe filled with water, soil, air, and so on. In this paper, we have discussed these experimental results. And then, we have done the numerical simulation to this method and those results are also discussed.

Deformation of Metal Pipe due to Underwater Shock Wave

1999 ◽  
Vol 121 (2) ◽  
pp. 176-180 ◽  
Author(s):  
S. Itoh ◽  
A. Kira ◽  
Z.-Y. Liu ◽  
S. Nagano
Keyword(s):  
Shock Wave ◽  
Numerical Calculation ◽  
Radial Direction ◽  
Maximum Velocity ◽  
Underwater Shock Wave ◽  
Metal Pipe ◽  
Copper Pipe ◽  
Metal Pipes ◽  
Underwater Shock ◽  
Aluminum Pipe

The deformation process of the metal pipes, accelerated by underwater shock wave resulting from the underwater detonation of explosive inside the metal pipe, was investigated by means of both the optical observation experiment and the numerical calculation. The expanding deformation of metal pipes was experimentally viewed by both framing and streak photographic means. A computer code based on the arbitrary Lagrangian and Eulerian (ALE) method was used to perform the numerical simulation on this problem. It has confirmed that the deformations of the metal pipes obtained from the streak photographs agree quite well with those obtained by the numerical calculation. The experimental and numerical results both show that the expanding velocity along the radial direction in aluminum pipe is larger than that in copper pipe, under the same loading conditions; and also, the time needed to reach the maximum radial velocity is shorter in aluminum pipe than in copper pipe. The calculations clearly indicate that the metal pipes are able to acquire a maximum expanding velocity along the radial direction in a very short time after the beginning of the action of underwater shock wave, and also this maximum velocity value only decreases a little in the later time period.

High Pressure Generation Using Underwater Explosion of a Spiral Explosive in a Conical Vessel

2004 ◽  
Vol 126 (2) ◽  
pp. 258-263
Author(s):  
Toru Hamada ◽  
Shigeru Itoh ◽  
Kenji Murata ◽  
Yukio Kato
Keyword(s):  
Shock Wave ◽  
Characteristic Curve ◽  
Three Dimensional ◽  
Underwater Explosion ◽  
Initial Pressure ◽  
Maximum Pressure ◽  
Underwater Shock Wave ◽  
Expansion Curve ◽  
Underwater Shock ◽  
Manganin Gauge

An explosive configuration was studied so that the underwater shock wave converges at the tip of the explosive, and a three-dimensional spiral configuration was obtained. This spiral configuration need to be analyzed theoretically due to the relation of propagation velocity of underwater shock wave, detonation velocity of the explosive and a configuration of vessel to charge the explosive. In order to study an effect of the convergence, pressure measurement at the spiral center was carried out by using a manganin gauge. Therefore, when SEP was used in this experiment, the maximum pressure value was 17.7 GPa. This maximum pressure value is higher than the pressure value of underwater shock wave generated from the underwater explosion of a straight configuration. Furthermore, this maximum pressure value was higher than C-J pressure of SEP. An initial pressure of underwater shock water shock wave that can obtain from an isentropic expansion curve of SEP and a characteristic curve of water is 5.7 GPa, and C-J pressure of SEP is 15.9 GPa. From the above-mentioned, the effect of spiral convergence could be shown well.

Effects of Steel Case on Underwater Shock Wave

2011 ◽  
Vol 52-54 ◽  
pp. 943-948
Author(s):  
Ji Li Rong ◽  
Da Lin Xiang ◽  
Jian Li
Keyword(s):  
Shock Wave ◽  
Peak Pressure ◽  
Underwater Explosion ◽  
Steel Shell ◽  
Cylindrical Charge ◽  
Underwater Shock Wave ◽  
Shock Wave Energy ◽  
Lag Effect ◽  
Underwater Shock ◽  
Different Thickness

The effects of steel case confinement for the aluminized explosive on underwater explosion(UNDEX) were experimentally and numerically investigated. The experimental results using 1kg cylindrical charge cased 6mm steel shell, show that steel case enhance the peak pressure, impulse, shock wave energy and decay time relative to the bare charge. The effect of different thickness of steel case was analyzed. With the increase of the case thickness, the shock wave were enhanced first and weaken later, and there is a lag-effect for the peak pressure of shock wave. There is an optimal case thickness which could maximum enhance the peak pressure. According to dimensional analysis, it's found that the ratio of case mass and charge mass( ) is a better dimensionless parameter to estimate UNDEX for a cased charge.

scholarly journals Fundamental Characteristics of Underwater Shock Wave due to Underwater Explosion of High Explosives.

1996 ◽  
Vol 62 (601) ◽  
pp. 3278-3283
Author(s):  
Shigeru ITOH ◽  
You NADAMITSU ◽  
Akio KIRA ◽  
Shiro NAGANO ◽  
Masahiro FUJITA ◽  
...  
Keyword(s):  
Shock Wave ◽  
Underwater Explosion ◽  
High Explosives ◽  
Underwater Shock Wave ◽  
Underwater Shock

Basic Study on the Crushing of Frozen Soil by Shock Loading

2007 ◽  
Author(s):  
Toshiaki Watanabe ◽  
Hironori Maehara ◽  
Masahiko Otsuka ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
High Speed ◽  
Shock Loading ◽  
Underwater Explosion ◽  
Frozen Soil ◽  
High Speed Camera ◽  
Underwater Shock Wave ◽  
Basic Study ◽  
Underwater Shock ◽  
A New Technique

The aim of study is to confirm a new technique that can crush the frozen soil and/or ice block using underwater shock wave generated by the underwater explosion of explosive. This technique can lead to the earlier sowing, which can have the larger harvest because the duration of sunshine increases. Especially, in Hokkaido prefecture, Japan, if the sowing is carried out in April, we can expect to have 150% of harvest in the ordinary season. This technique is effective against the cold regions. For example, Korea, China, Mongolia, Russia, Norway, and Sweden, etc. At first, we carried out experiments usung a detonating fuse and ice block. The process of ice breaking was observed by means of a high-speed camera. In order to check about that influence we tried to give an actual frozen soil a shock wave.

Influence of Pressure Vessel Shape on Explosive Forming

2018 ◽  
Author(s):  
Hirofumi Iyama ◽  
Masatoshi Nishi ◽  
Yoshikazu Higa
Keyword(s):  
Shock Wave ◽  
Pressure Vessel ◽  
Underwater Explosion ◽  
Metal Plate ◽  
Reflected Shock Wave ◽  
Underwater Shock Wave ◽  
Reflected Shock ◽  
Final Deformation ◽  
Underwater Shock ◽  
Explosive Forming

The explosive forming is a characteristic forming method. This technique is a metal forming using an underwater shock wave. The underwater shock wave is generated by underwater explosion of the explosive. The metal plate is formed with involving the high strain rate on this technique. In generally, the pressure vessel is used in this method due to the effective utilization of the explosion energy. The underwater shock wave is propagated in water and reflected on inside wall of the pressure vessel. This reflected shock wave is affected on the deformation shape of a metal plate. Therefore, the inside shape of pressure vessel is often changed. In other words, the shape of pressure vessel is changed, the shock pressure distribution on the metal plate and it is possible that final deformation shape of the metal plate is changed. Some numerical simulations and experiments have been carried out to clear the influence of the inside shape of pressure vessel in the explosive forming. This paper is included the results and discussions on the numerical simulation and experiment used those conditions.

An Investigation on the Properties of Underwater Shock Waves Generated in Underwater Explosions of High Explosives

1997 ◽  
Vol 119 (4) ◽  
pp. 498-502 ◽  
Author(s):  
S. Itoh ◽  
Z. Liu ◽  
Y. Nadamitsu
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Numerical Simulations ◽  
Underwater Explosion ◽  
High Explosives ◽  
Underwater Shock Wave ◽  
Underwater Explosions ◽  
Expansion Test ◽  
Gas Products ◽  
Underwater Shock

A cylinder expansion test for high explosives was carried out to determine JWL parameters. Using the JWL parameters, we carried out numerical simulations of the underwater shock waves generated by the underwater explosion of the high explosives. Our results showed that the behavior of the underwater shock waves at the vicinity of the explosives differs greatly from that far from the explosives. Especially, the strength of the underwater shock wave nearby the explosive rapidly decreases due to the effect of the expansion of the gas products.

A New Method of Explosive Welding Performed by Effective Application of Reflected Underwater Shock Wave

2006 ◽  
Author(s):  
Kazumasa Shiramoto ◽  
Masahiro Fujita ◽  
Hirofumi Iyama ◽  
Yasuhiro Ujimoto ◽  
Shigeru Itoh
Keyword(s):  
Shock Wave ◽  
Explosive Welding ◽  
Underwater Explosion ◽  
Shock Pressure ◽  
Experimental Results ◽  
New Method ◽  
Underwater Shock Wave ◽  
Effective Application ◽  
Welding Method ◽  
Underwater Shock

In this report, we propose a new explosive welding method, and the welding is performed at employing underwater shock pressure produced by the underwater explosion of an explosive placed at one side almost vertical to the specimen to be welded. In order to prevent the reduction of the shock pressure with the distance away from explosive, a steel reflector is placed over the area of the specimen. The effects of the reflector are investigated based on the experimental results and the process is numerically analyzed results.

Explosive Welding of Metal Pipe Using Underwater Shock Wave

2003 ◽  
Vol 2003.2 (0) ◽  
pp. 303-304
Author(s):  
Hirofumi IYAMA ◽  
Kazuyuki HOKAMOTO ◽  
Shigeru ITOH
Keyword(s):  
Shock Wave ◽  
Explosive Welding ◽  
Underwater Shock Wave ◽  
Metal Pipe ◽  
Underwater Shock
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