High-speed photographic studies of impact on thin layers of emulsion explosive

1984 ◽  
Vol 9 (3) ◽  
pp. 77-81 ◽  
Author(s):  
V. Krishna Mohan ◽  
J. E. Field ◽  
G. M. Swallowe
Keyword(s):  
High Speed ◽  
Thin Layers ◽  
Emulsion Explosive ◽  
Photographic Studies

Paper F–5: High-Speed Photographic Studies of Electrically Exploded Metal Films and Wires

1962 ◽  
Vol 71 (1A) ◽  
pp. 283-289
Author(s):  
Louis Zernow ◽  
George Woffinden ◽  
Fulton W. Wright
Keyword(s):  
High Speed ◽  
Metal Films ◽  
Photographic Studies

The ignition of a thin layer of explosive by impact

1974 ◽  
Vol 338 (1612) ◽  
pp. 77-93 ◽  
Keyword(s):  
Pressure Drop ◽  
Thin Layer ◽  
High Speed ◽  
Large Scale ◽  
Flow Speed ◽  
Thin Layers ◽  
Drop Weight ◽  
Flow Speeds ◽  
Show Evidence ◽  
Weight Impact

The behaviour of thin layers of solid materials under drop-weight impact is studied with the aid of high-speed photographic and pressure-measuring techniques. Photographic sequences taken with a high-speed framing camera show that explosive materials suffer large-scale deformation before initiation of explosion. The sample may undergo plastic flow in bulk, show evidence of partial fusion, and even (with PETN) melt completely. There is also evidence of Munroe jetting and instability of flow of material at the anvil/layer interfaces. The flow speed of the sample during these processes is considerable and may reach 300 m/s. When ignition of the layer occurs it does so at a small number of local hot spots, following which rapid combustion develops at speeds of 200-700 m/s. Strain-gauge measurements show that the pressures attained during drop-weight impact are typically 0.5-1 GPa (5–10 kbar) and the duration of impact 300–500 μs. In the course of impact of a thin layer of granular material a sharp pressure drop may occur, frequently from several hundred MPa down to zero. With an explosive layer, ignition occurs immediately following the instant of the pressure drop. The sudden fall in pressure is due to mechanical failure of the sample, and correlation of the two experiments shows that this is the cause of the very high flow speeds attained during impact. On the basis of these results a possible mechanism of ignition is suggested.

scholarly journals Enhancement of Explosive Welding Possibilities by the Use of Emulsion Explosive/ Rozwój Mozliwości Łączenia Wybuchowego Przez Użycie Emulsji Wybuchowych

2014 ◽  
Vol 59 (4) ◽  
pp. 1587-1592 ◽  
Author(s):  
B. Zlobin ◽  
V. Sil’Vestrov ◽  
A. Shtertser ◽  
A. Plastinin ◽  
V. Kiselev
Keyword(s):  
Thin Layer ◽  
Physical Properties ◽  
Detonation Velocity ◽  
Explosive Welding ◽  
Hardened Steel ◽  
Explosion Welding ◽  
Thin Layers ◽  
Emulsion Explosive ◽  
Emulsion Explosives ◽  
Thermo Physical Properties

Abstract Explosive welding is an effective method of joining of various metals and alloys. However, when the materials with very different strength and thermo-physical properties are welded or thin-layer cladding is performed, the difficulties occur which call for extra investigations. In the present paper, with the couples of steel / carbide composite and copper / hardened steel used as examples, under study were the peculiarities of bonding formation by the explosive welding of metals with highly differing properties. The experiments were carried out with emulsion explosive containing hollow micro-spheres and detonating in thin layers with the low (2 - 3 km/s) detonation velocity. Obtained results show that the emulsion explosives enable to extend the explosion welding potentiality.

Bubble collapse and the initiation of explosion

1991 ◽  
Vol 435 (1894) ◽  
pp. 423-435 ◽  
Keyword(s):  
Shock Wave ◽  
Plane Wave ◽  
High Speed ◽  
Bubble Collapse ◽  
Thin Sheets ◽  
Subsequent Reaction ◽  
Emulsion Explosive ◽  
Wave Generator ◽  
Ignition Mechanism ◽  
Cylindrical Cavities

Experiments were conducted to investigate the initiation of an emulsion explosive containing cavities. Cylindrical cavities were created in thin sheets of either gelatine or an ammonium nitrate/sodium nitrate emulsion confined between transparent blocks. Shocks were launched into the sheets with either a flier-plate or an explosive plane-wave generator so as to collapse the cavities asymmetrically. The closure of the cavities and subsequent reaction in the explosive was photographed by using high- speed framing cameras. The collapse of the cavity proceeded in several stages. First, a high-speed jet was formed which crossed the cavity and hit the downstream wall sending out a shock wave into the surrounding material. Secondly, gas within the cavity was heated by rapid compression achieving temperatures sufficient to lead to gas luminescence. Finally, the jet penetrated the downstream wall to form a pair of vortices which travelled downstream with the flow. When such a cavity collapsed in an explosive, a reaction was observed to start in the vapour contained within the cavity and in the material around the heated gas. The ignition of material at the point at which the jet hit was found to be the principal ignition mechanism.

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