View source for Brisance

{{Short description|Shattering ability of a high explosive}}
{{Wiktionary}}

'''Brisance''' ({{IPAc-en|b|r|ɪ|ˈ|z|ɑ:|n|s}}; {{ety|fr|briser|break, shatter}}<ref>{{cite web|title=Brisance|url=http://dictionary.reference.com/browse/Brisance|work=Dictionary.com Unabridged|publisher=Random House, Inc.|accessdate=31 March 2014}}</ref>) is the shattering capability of a [[high explosive]], determined mainly by its [[detonation]] pressure.

==Application==
Brisance is of practical importance in [[explosives engineering]] for determining the effectiveness of an explosion in [[drilling and blasting|blasting]] and [[Quarry|quarrying]], and in weaponry such as [[fragmentation (weaponry)|fragmenting]] shells, [[bomb]] casings, [[grenade]]s, and [[plastic explosive]]s. The sand crush test<ref>{{cite book |url=https://books.google.com/books?id=EdfHxMJtIBUC |title=The Sand Test for Determining the Strength of Detonators |publisher=[[United States Department of the Interior]] |first1=C. G. |last1=Storm |first2=W. C. |last2=Cope |date=1916 |via=Google Books}}</ref> and [[Trauzl lead block test]] are commonly used to determine the relative brisance in comparison to [[trinitrotoluene|TNT]] (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 a [[piston]] or a bullet, brisance is likely to be undesirable, because the objective will be to ''move'' the 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 as [[carburettor|carburetted]] fuel/air mixes in vehicle piston engines, or [[nitrocellulose]] fibres or grains of controlled textures in [[firearm]] [[Cartridge (firearms)|cartridge]]s. 

For certain types of blasting, as in some [[civil engineering]] works, 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 as [[slate]], 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 purpose [[blasting powder]] of ''low'' brisance is necessary.<ref name="Pid">PIDDOCK, S. (2007). Slate, slate, everywhere slate: The cultural landscapes of the Willunga slate quarries, South Australia. Australasian Historical Archaeology, 25, 5-18. Retrieved from http://www.jstor.org/stable/29544573</ref> 

In shattering hard rock or military defences, high brisance generally is necessary, so [[Explosive#High explosives|high explosive]]s with extremely high [[detonation velocity]] are used as far as is practical.  One of the most brisant of the conventional explosives is cyclotrimethylene trinitramine (also known as [[RDX]] or Hexogen).<ref>{{cite book|title=TM 9-1300-214|publisher=US Army}}[http://www.freepyroinfo.com/Pyrotechnic/Pyrotechnic_Books/Tm_9_1300_214_U_S_Military_Explosives.pdf] {{webarchive |url=https://web.archive.org/web/20100816140250/http://www.freepyroinfo.com/Pyrotechnic/Pyrotechnic_Books/Tm_9_1300_214_U_S_Military_Explosives.pdf |date=August 16, 2010 }}</ref> RDX is the explosive agent in the plastic explosive commonly known as [[C-4 (explosive)|C-4]], constituting 91% RDX by mass.<ref>{{cite web |work=Global Security |title=Explosives – Compounds |url=https://www.globalsecurity.org/military/systems/munitions/explosives-compositions.htm}}</ref>

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==
* [[Relative effectiveness factor]]
* [[Table of explosive detonation velocities]]

==References==
{{Reflist}}
* A. Bailey & S.G. Murray, ''Explosives, Propellants & Pyrotechnics'', Brassey's (UK) Ltd., London, 1989.

[[Category:Explosives]]