Brisance
Brisance(/brɪˈzɑːns/;fromFrenchbriser'to break, shatter', fromCelticbrissim'to break'[1]) is the shattering capability of ahigh explosive,determined mainly by itsdetonationpressure.
Application
[edit]Brisance is of practical importance inexplosives engineeringfor determining the effectiveness of an explosion inblastingandquarrying,and in weaponry such asfragmentingshells,bombcasings,grenades,andplastic explosives.The sand crush test[2]andTrauzl lead block testare commonly used to determine the relative brisance in comparison toTNT(which is considered a standard reference for many purposes).
The value of brisance depends on the application. At one extreme, if an explosive is to be used for propulsion, e.g. by driving apistonor a bullet, brisance is likely to be undesirable, because the objective will be tomovethe load, not to shatter it or the engine or firearm, nor to produce a loud report. Such propulsive charges are designed to burn controllably, such ascarburettedfuel/air mixes in vehicle piston engines, ornitrocellulosefibres or grains of controlled textures infirearmcartridges.
For certain types of blasting, as in somecivil engineeringworks, the objective is to loosen the undesired material with the least amount of explosion and expense, both in explosive and safety precautions. Similarly, in quarrying a product such asslate,in which the objective is to loosen it from surrounding rock with as little damage as possible, no more brisance than is necessary to split off the valuable product profitably, without unacceptable waste, is desired. For this purposeblasting powderoflowbrisance is necessary.[3]
In shattering hard rock or military defences, high brisance generally is necessary, sohigh explosiveswith extremely highdetonation velocityare used as far as is practical. One of the most brisant of the conventional explosives is cyclotrimethylene trinitramine (also known asRDXor Hexogen).[4]RDX is the explosive agent in the plastic explosive commonly known asC-4,constituting 91% RDX by mass.[5]
Fragmentation occurs by the action of the transmitted shock wave, the strength of which depends on the detonation pressure of the explosive. Generally, the higher this pressure, the finer the fragments generated. High detonation pressure correlates with high detonation velocity, the speed at which the detonation wave propagates through the explosive, but not necessarily with the explosive's total energy (or work capacity), some of which may be released after passage of the detonation wave. A more brisant explosive, therefore, projects smaller fragments but not necessarily at a higher velocity than a less brisant one.
See also
[edit]References
[edit]- ^"Brisance".Dictionary.com Unabridged.Random House, Inc.Retrieved31 March2014.
- ^Storm, C. G.; Cope, W. C. (1916).The Sand Test for Determining the Strength of Detonators.United States Department of the Interior– via Google Books.
- ^PIDDOCK, S. (2007). Slate, slate, everywhere slate: The cultural landscapes of the Willunga slate quarries, South Australia. Australasian Historical Archaeology, 25, 5-18. Retrieved fromhttp://www.jstor.org/stable/29544573
- ^TM 9-1300-214.US Army.[1]ArchivedAugust 16, 2010, at theWayback Machine
- ^"Explosives – Compounds".Global Security.
- A. Bailey & S.G. Murray,Explosives, Propellants & Pyrotechnics,Brassey's (UK) Ltd., London, 1989.