Initiation and detonation

M. Sultanoff, PrRoySoc 246A, 274-81 (1958) (Sympathetic deton and initiation by impact) 21) Dunkle s Syllabus (1957-1958), p 152 (Some work conducted at BRL on sympathetic deton is briefly discussed)... 

M. Sultanoff, "Sympathetic Detonation and Initiation by Impact , PrRoySoc 246A,... 

Functioning. The fuze becomes armed after the locking segment moves into the armed position (this occurs at a rotational speed of 6000 to 8500 rpm) and the delay arming shutter moves into the aimed position (this occurs at a rotational speed of 7000 to 8500 rpm). Upon either direct or graze impact, the steel ball moves the striker assembly forward until the striker needle hits the detonator and initiates it. The impulse will be transmitted thru the lead to booster and then to the main charge... 

In the Trauzl test, trinitrotriazidobenzene gives 90% as much net expansion as PETN tctryl gives 70%, TNT 60%, mercury fulminate 23%, and lead azide 16%. Used as a high explosive in compound detonators and initiated with lead azide, trinitrotriazidobenzene is about as strong as PETN and is stronger than tetryl. 

Fig 25 Relationship Between Distance to Detonation and Initial Shock Pressure for Various Explosives. The open symbols for PETN represent the maximum and minimum distances which could be measured. The points are located at the calculated pressures. The data for PETN are taken from Seay and Seely (Ref 5)... 

In Sec. 2, we review the reactive empirical bond order potentials that we have developed over the last decade which possess these essential characteristics. Our model systems and computational techniques are also described. Simulations using the first of our models to exhibit classic detonation behavior are discussed in Sec. 3, where results involving both detonation and initiation are presented. In Sec. 4, the results of our molecular dynamics simulations are compared in detail with the predictions of continuum theory. Then, in Sec. 5, we review some simulations that raise... 

The lack of published works on this subject is due to two causes. First, the theory of the electronic structure and electronic transport has only recently become anywhere near adequate to cope with materials as complex as lead azide on the one hand and 1,3,5,7-tetranitro 1,3,5,7-tetraza cyclooctane (HMX) on the other. Second, the hydrodynamic theory of detonations has been remarkably successful in explaining the velocities of detonations, and initiation has been reasonably well explained in most cases as ultimately thermal in origin. ... 

Relationship Between Distance to Detonation and Initial Shock Pressure for Various Explosives S 78... 

Initiators. Explosives such as mercury fulminate and certain metallic azides which are extremely sensitive to mechanical shock, and are accordingly used in small quantities in detonators to initiate the explosion of larger masses of less sensitive material. 

Tetiyl. 2,4,6-Trinitrophenylmethylm tramine (tetryl) was used ia pressed form, mostly as a booster explosive and as a base charge ia detonators and blasting caps because of its sensitivity to initiation by primary explosives and its relatively high energy content. Properties are presented ia Table 11 (173). Batch and continuous processes for the production of tetryl have been developed. Tetryl is no longer used ia the United States and has been replaced by RDX (174-178). 

The pressure developed by decomposition of acetylene in a closed container depends not only on the initial pressure (or more precisely, density), but also on whether the flame propagates as a deflagration or a detonation, and on the length of the container. For acetylene at room temperature and pressure, the calculated explosion pressure ratio, / initial > deflagration and ca 20 for detonation (at the Chapman-Jouguet plane). At 800 kPa (7.93... 

Relatively little information is available on the influence of initial pressure and initial temperature on detonation limits, in confined situations. The general effect of an increase in inidal pressure is to widen the detonations limits, and the same applies to an increase in the initial temperature. The widening is more marked for die upper limit. 

All NCN blasting agents and each of their components must be cap-insensitive, ie, incapable of being detonated when initiated by a No 8 blasting cap. Both Nitro-Carbonitrates and Amm nitrate are grouped by the ICC as oxidizing materials with normal transportation (yell°w label) being permitted (Ref 1)... 

Superfine PETN for use in EBW detonators and MDF is produced by quenching a hot ace tone soln in cold water. The resulting particle size distribution averages 10 microns, and irregular crystals are produced which are easier to initiate (Ref 80a)... 

Brisance and power are quantities that can be defined more exactly than sensitivity, and PETN is one of the most powerful and brisant expls known. It is also among the most studied expls, from both exptl and theoretical points of view. In this section we will consider PETN s steady detonation parameters, thermochemistry, and initiation characteristics,... 

Related to both DDT and initiation by shock is the initiation of solid expls by gas detonations. Weiss et al (Ref 61) found that PETN at 0.7g/cc could be initiated by a gas detonation of 21 atm initial pressure, which produced an initial (presumably in the PETN) pressure of 2kbar. Under these conditions initiation delay in the PETN was less than one microsecond... 

VIII. Explosive Characteristics. Picric Acid is generally considered to be a relatively insensi tive but brisant expl. On a qualitative sensitivity scale of comparing common expls, PA would be judged to be more sensitive than TNT but appreciably less sensitive than Tetryl. Its power and brisance are also similar to those of TNT (112% TNT in the Ballistic Mortar 101% of TNT in the Trauzl Block and 107% in the plate dent test (Ref 48). In this section we will consider the steady detonation parameters. initiation characteristics and potential hazards of PA... 

A violent explosion of Picric Acid in a Manchester factory in 1887 was ascribed to the formation of picrates. Burning, molten Picric Acid flowed down onto lithopone, forming lead picrate which in consequence caught fire. The latter, being an initiator, detonated and caused the Picric Acid to detonate... 

Lu, Vyn, Sandus and Slagg (Ref 17) conducted ignition delay time and initiation studies on solid fuel powder-air mixts in an attempt to determine the feasibility of solid-air detonations. The materials investigated included Al, Mg, Mg-Al alloy, C and PETN. Ignition delay time was used as a method of screening the candidate fuels for further work in initiation studies which determined detonation wave speed, detonation pressure, detonation limits, initiation requirements, and the effect of particle size and confinement. The testing showed the importance of large surface area per unit mass, since the most... 

MECHANICAL initiators PERCUSSION PRIMERS, STAB DETONATORS, AND FRICTION PRIMERS... 

Although it is evident that initiators represent a broad spectrum of items and designs, both percussion and electric, the contents of this treatise will deal only with three selected types of percussion items ie, percussion primers, stab primers and/or detonators, and friction primers... 

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