Plastic Detonation Wave

Detonation Wave, Plastic. These waves are complicated by the fact that there is no longer a linear relation between stress and strain. A plastic wave does not maintain its form as it progresses but rather the front of increasing stress tends to become longer and longer, at least in normal cases. The reflection at a discontinuity resembles generally the reflection of an elastic wave. Reflection of stress wave at a fixed end in an elastic member gives rise to stresses strains that ass exactly double those in the incident wave 

Properties of plastic wave, as well as of elastic wave were determined by Minshall (Ref 39) using pin contactors and crystals (See also Refs 85b and 92a) 

Detonation Wave, plate Velocities in Impulse Loading by. This subject was discussed in the paper entitled Plate Velocities in Impulse Loading by Detonation Waves , presented by RiB. Clay et al of Univ of Utah at the Symposium on Shock Waves in Process Equipment Annual Meeting of American Institute of Chemical Engineers, Chicago, 

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The transmission of such a stress will depend on the elastic nature of the material, and the optimum condition for transmission of the breaking wave is achieved in perfectly elastic materials, such as individual crystals. The soft, plastic or fluid materials which tend to damp out elastic waves have a similar tendency with detonation wave... 

Detonation Wave, Elastic. An elastic wave is one which temporarily disturbs the medium thru which it traverses ie, after passage of the wave, the medium returns to its original state. Properties of elastic waves and of plastic waves were determined by Minshall (Ref 39) using pin contactors and crystals. Nawa (Ref 85) carried out theoretical and exptl studies on the transition of the energy generated by expls and the wave shapes of the generated elastic waves. The amplitude of an elastic wave was theoretically detd and experimentally correlated with sp energy and/or brisance of expls (See also Ref 92a)... 

Mg, 0.25—1.0% Mn and small amounts of Fe Si), or of Sierracin (a thermosetting plastic which is not attacked by NMe as are most plastics). The plate velocities are accdg to Duff Houston (Ref 38a), related to the pressure in the explosive at a distance back in the explosive approximately proportional to the plate thickness. The free surface velocities were measured using a smear camera technique, described by Davis Craig (Ref 67a). Here the apparent position of the image of an object reflected in the free surface was recorded as a function of time. The measurements showed that a real detonation wave consists at the charge axis of three zones ... 

CA 49, 10625 (1955) (Structure of detonation wave front of gases was studied by method of shock tube) (See its abstract under Detonation Wave Structure) 38a) R.E. Duff E. Houston, 2nd ONRSympDeton (1955), p 225 (See under Detonation Wave Structure Measurements in Condensed Explosives) 39) S. Minshall, JApplPhys 26, 463- 69 (1955) (Properties of elastic and plastic waves determined by pin contactors and crystals) 40) C.G. Dunkle, "Introduction to Theory of Detonation of Explosives, Syllabus of 21 Nov 1955 and Lecture Delivered at Picatinny Arsenal on 13 Dec, 1955 (Structure of the deton wave)... 

Munson, "The Influence of Mechanical Properties on Wave Propagation in Elastic-Plastic Materials, Ibid, pp 295-304 93) F. David et al, "Oblique Impact of a Layer of Explosive by a Metal Plate , Ibid, pp 381-85 (Formation of oblique deton wave and of over-detonation wave by such impact)... 

Nonel fuse, invented by Nitro Nobel AB in Sweden, consists of a thick plastic tube of bore about 1 mm, the inside surface of which is dusted with a small amount of powdered high explosive. If a shock wave is formed at one end of the tube the explosive powder is raised to a dust and a stable detonation at velocity 2000 m s 1 proceeds indefinitely along the fuse. The plastic itself is unaffected and the only outside effect is a flash of light seen through the tube walls. This therefore is an extremely safe method of propagating a detonation from one place to another. 

A recent alternative to shaped charges is known as the squashhead projectile. As the name implies, this contains a plastic explosive which spreads on impact so as to make contact with the largest possible area of the tank before detonating. When the explosive detonates, reflection of the shock wave causes a scab of metal to be displaced from the inside surface of the armour plate (see p. 135). The effect inside the tank can therefore be greater than is the case with a shaped charge which may do little more than penetrate the armour. The amount of scabbing is approximately proportional to the area of contact of the explosive at the moment of detonation. 

The sensitivity of expls is a characteristic of great importance and can be correlated with the rate of deton. Perfect crysts and other nearly perfect elastic materials are the most sensitive, while liquids or colloids (plastic, fluid or hard) resist initiation and also have tendency to damp out-the wave of deton. The sensitivities of endothermic and exothermic compds are different and this causes them... 

Solids 12, 59 - 65 (1964) "A Generalized Theory of Strain- Rate- Dependent Plastic Wave Propagation in Bars 86) M. Lutzky, "The Flow Field Behind a Spherical Detonation in TNT, Using the Landau- Stanyukovich Equation, USNOL-White Oak, NOLTR 64-40 Dec 1964)... 

A recent example of chemical energy ammo utilizing this principle are so-called HESH (High Explosive Squash Head) rounds. In this type of round, a large quantity of plastic HE is carried in a shell. When it strikes armor plate, the HE filling mushrooms on the armor face, and a base fuze detonates it. This system does not go thru the plate — the shock wave from the detonation is transmitted thru it. When it reaches the far side it is reflected back, which overstresses the metal on the inside of the plate so that a large scab , often several feet across, is de-... 

Nonel. Trade name of a new non-electric device for the firing of expl charges. The basic unit consists of, in place of electrical lines, safety fuses or detonating cord, a plastic hose (3mm diam) the inner wall of which is coated with a thin layer of expl. A shock wave initiated by a special initiator passes thru the hose with a speed of approx 2000m/sec. A spectator observes this shock wave process as a flash in the hose, which is not destroyed by the shock wave In order to initiate a charge, the Nonel line must be combined with a conventional detonator, and branching is possible... 

The transition to detonation occurs as the dislocation tunneling probability approaches unity. While the molecular excitation and dissociation processes are entirely quantum mechanical processes the detonation velocity is accessible through classical means. The detonation velocity, D, is the velocity of the plastic wave where energy dissipation and molecular dissociation take place, D = v. But v =... 

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