Experimental and numerical study on penetration of micro/nano diamond particle into metal by underwater shock wave

In order to develop composite materials, new attempting was conducted. When an explosive is exploded in water, underwater shock wave is generated. Metal plate is accelerated by the underwater shock wave and collided with diamond particles at high velocity. In this paper, pure aluminum and magnesium alloy plates are used as matrix. Micro and nano sized diamond particles were used as reinforcement. Micro diamond particles were closely coated on metal surface. Some of micro diamond particles were penetrated into aluminum. Improvement of base metal property (wearing resistance) was verified by wear test for recovering metal plate. In order to confirm the deformation of the aluminum plate during the collision with diamond particles, simplified numerical simulation was conducted by using LS-DYNA software. From the result of numerical simulation, large deformation of aluminum and process of particle penetration were verified

Research on Initiation Sensitivity of Solid Explosive and Planer Initiation System

Firstly, recently, there are a lot of techniques being demanded for complex process, various explosive initiation method and highly accurate control of detonation are needed. In this research, the metal foil explosion using high current is focused attention on the method to obtain linear or planate initiation easily, and the main evaluation of metal foil explosion to initiate explosive was conducted. The explosion power was evaluated by observing optically the underwater shock wave generated from the metal foil explosion. Secondly, in high energy explosive processing, there are several applications, such as shock compaction, explosive welding, food processing and explosive forming. In these explosive applications, a high sensitive explosive has been mainly used. The high sensitive explosive is so dangerous, since it can lead to explosion suddenly. So, for developing explosives, the safety is the most important thing as well as low manufacturing cost and explosive characteristics. In this work, we have focused on the initiation sensitivity of a solid explosive and performed numerical analysis of sympathetic detonation. The numerical analysis is calculated by LS-DYNA 3D (commercial code). To understand the initiation reaction of an explosive, Lee-Tarver equation was used and impact detonation process was analyzed by ALE code. Configuration of simulation model is a quarter of circular cylinder. The donor type of explosive (SEP) was used as initiation explosive. When the donor explosive is exploded, a shock wave is generated and it propagates into PMMA, air and metallic layers in order. During passing through the layers, the shock wave is attenuated and finally, it has influence on the acceptor explosive, Comp. B. Here, we evaluate the initiation of acceptor explosive and discuss about detonation pressure, reactive rate of acceptor explosive and attenuation of impact pressure

Optical Examination of Shockwave Propagation Induced by an Underwater Wire Explosion

We have been investigating underwater-explosion-induced shockwave-propagation phenomena for use in a robust food-processing system. This system comprises a high-voltage capacitor bank with gap switch, water tank, and wire explosive. We carried-out optical observation of the shockwave generated by a wire explosion using electrical discharge in the water tank. Simultaneously, we measured the shock pressure and investigated the effects of various electrical characteristics upon the shockwave-propagation phenomena. To obtain various strengths of the underwater shockwave, 0.6-, 1.0-, and 1.4-mm-wide wires made from 1.0-mm-thick aluminum plates were used at various voltages. As an example, a shockwave having a propagation velocity of 1,600 m/s was observed using the explosion of the 1.0-mm-wide aluminum wire. We found that the strength of the shockwave could be well-controlled by the discharge voltage and wire size

Effects of improving current characteristics of spark discharge on underwater shock waves

We have been developing a food-processing device that uses underwater shock waves generated by spark discharges at an underwater spark gap. Underwater shock waves can be used in food processing for softening, fracturing and sterilization. These technologies are attracting attention because the food is not heated during processing, so it does not change flavour. In this study, we develop a rice-powder manufacturing system using the fracturing effect provided by underwater shock waves. Because rice grains are very hard, the process must be applied repeatedly using a momentary high pressure to fracture the grains. The fast repeated generation of shock waves should provide high pressures from low energies. Therefore, we aim to achieve higher pressures from low energies expended by the underwater gap discharge. We increase the pulse compression rate by decreasing the circuit impedance of the device and increasing the charging voltage. Using optical observations and a pressure sensor, we measure the high pressure developed by the underwater shock wave and the rise time of the discharge current. We find that we can decrease the rise time of the discharge current by 17% while maintaining the peak current, and simultaneously increase the high pressure of the underwater shock wave by 135%

High cooling rates and metastable phases at the interfaces of explosively welded materials

International audienceDuring an explosion, the interfaces of welded materials experience fast heating due to high strain rate severe plastic deformation. This leads to the formation of local zones, where melting and mixing of welded materials is observed. These zones are frequently referred to as vortexes, eddies or swirls, due to the specific rotational movement of materials during mixing. This study is primarily devoted to the discussion of the structures that appear in these zones. Simple approaches to estimate the heating and cooling rates at the interfaces between explosively welded materials were proposed. It was concluded that the heating rate at the interfaces was of the order of 10(9) K/s, while the cooling rate achieved 10(7) K/s. Several combinations of explosively welded alloys (steel/steel, Ti alloy/steel, Zr/Cu, Zr/Ni, Ta/Cu, Al/ magnesium alloy and Cu/brass) were thoroughly analyzed using scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. In most of these combinations, metastable crystalline, quasicrystalline or glassy phases were observed. The formation of different types of metastable phases is discussed with respect to the compositions of the welded alloys. It was concluded that solidification conditions at the interfaces of explosively welded materials are similar to those during rapid solidification. Thus, the results of numerous experiments on rapid solidification of alloys could be applied to analyze the structures that appear in mixing zones. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

Plastic instability of sandwich sheet materials during rolling

55.00; Translated from Japanese (Bull. Jpn. Inst. Met. 1987 v. 26(11) p. 1028-1035)Available from British Library Document Supply Centre- DSC:9022.06(BISI-Trans--26484)T / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Thermal stability and mechanical properties of explosion-welded SUS 304 steel wire mesh/Al composite

Translated from Japanese (Nippon Kinzoku Gakkai-Shi 1988 v. 52(8) p. 826-833)Available from British Library Document Supply Centre- DSC:9022.06(BISI-Trans--27217)T / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo