Papers by Author: Shigeru Itoh

Abstract: Explosive forming is one of the effective metal forming methods using underwater shock wave generated by the detonation of an explosive. We have done the experiment of eccentric spherical free metal forming by this method. This free metal forming process does not use require expensive metal die. We used simple metal die with only circular edges and considered the metal plate formed to required shape using this method. It was possible to change the pressure distribution applied on the metal plate by changing the set-up position of explosive and the shape of the device. We have considered this method to cause lessen cost in the small production by various types of metal forming process. In this paper, we introduce the method of eccentric spherical free metal forming using underwater shock wave and present the experimental results.

Abstract: The food processing technology using a shock wave can prevent deterioration of the food by heat because it can process food in a short time. Generally, since the shock wave used for food processing is generated by underwater explosion, the load of a shock wave to the food becomes very complicated. Therefore, in order to process safely, it is important to clarify the behaviors of the shock wave and the bubble pulse generated by underwater explosion. In this research, in order to investigate the behavior of the shock wave in the water tank used for food processing, the optical observation experiment and the numerical simulation were performed. In the experiment, the shock wave generated by underwater explosion was observed with the high-speed video camera. The numerical simulation about the behavior of bubble pulse was performed using analysis software LS-DYNA. Comparing and examining were performed about the experimental result and the numerical simulation result. The result of the numerical simulation about the behavior of the shock wave generated by underwater explosion and the shock wave generated by the bubble pulse and the bubble pulse was well in agreement with the experimental result.

Abstract: In recent years in Japan, the demand of cryogenic fluids like a LH2, LNG is increasing because of the advance of fuel cell device technology, hydrogen of engine, and stream of consciousness for environmental agreement. On the other hand, as for fisheries as well, the use of a source of energy that environment load is small has been being a pressing need. We paid attention to the effective use of cold heat of the liquid fuel which is a cryogenic fluid. That method is to use a cold heat which an cryogenic fluid has, without a heat exchanger. The mixture of the extreme low temperature fluid and the normal temperature fluid becomes the cause which causes pressure vessel and piping system crush due to explosive boiling and rapid freezing. Therefore, we carried out the experiments related to promotion of evaporating cryogenic fluids, in the contact directly of the room temperature fluids and cryogenic fluids.

Abstract: In this study, a new processing technique of ginger using underwater shock wave has been studied. The extraction efficiency of ginger using controlled and shock wave method has been compared. The shock wave shows good improvement in the extraction efficiency of ginger.

Abstract: There are few research papers of liner shaped charge (LSC). In this time simplified LSC was made from an explosive and vertically-folded copper plate. In order to confirm a performance of the simplified LSC, steel cutting experiments were conducted by changing distance from the simplified LSC to target steel. Numerical analysis was also conducted by using Ls-dyna. Penetration depth was measured after experiments. Collision velocity of copper was calculated by using Gurnney equation. Numerical simulation model was made by SPH, because large deformation was occurred during collision of copper and steel penetration process. Results from numerical analysis were good correspondence with experimental results. Details are reported on this paper.

Abstract: The glass containers crushing process for recycling by using underwater shockwave was observed and the new cullet generation technique by explosive energy was proposed. In this study, the high-speed fracture behaviors of glass containers were visualized by using the high-speed photography and FEM simulation.

Abstract: The high-speed fracture phenomena of glass bottles by using underwater shock wave technique for recycling the glass containers were discussed. The proposed technique is an efficient method for the crushing of glass bottles. In this study, the influence of various explosive conditions, that is, the explosive shape, set position, amount, the bottle size and the contents of bottle, on the cullet size, which is the crushed glass fragments, was studied. Furthermore, the behaviors of underwater shock wave were observed by high-framing photograph and the high-speed fracture mechanism was clarified.

Abstract: The industrial applications of under shock wave have been investigated in our center. This paper concerns with the improvement of foods and wood using underwater shock wave. Underwater shock wave is easily generated by means of explosion of explosives or high voltage electric discharge in water. A detonating fuse and an electric detonator were used for generation of underwater shock wave, and apples were used as food sample for food processing experiments. The behavior of underwater shock wave was investigated by optical observations. The extraction and the amount of phenolic compounds in apple juice obtained from the shock treated sample were higher than that of control samples. It is considered that the underwater shock wave treatment for apples has a big possibility in food processing. The results of coffee bean and other food processing by underwater shock wave were presented at the conference. Moreover the properties of wood were well improved by shock loading. The resistance of wood has been improved significantly.

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 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.