In
explosives engineering, brisance (; , ) is the shattering capability of a
high explosive
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An e ...
, determined mainly by its
detonation
Detonation () is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations propagate supersonically through shock waves with ...
pressure.
Practical uses
Brisance is of practical importance for determining the effectiveness of an explosion in
fragmenting shells,
bomb
A bomb is an explosive weapon that uses the exothermic reaction of an explosive material to provide an extremely sudden and violent release of energy. Detonations inflict damage principally through ground- and atmosphere-transmitted mechan ...
casings,
grenade
A grenade is an explosive weapon typically thrown by hand (also called hand grenade), but can also refer to a shell (explosive projectile) shot from the muzzle of a rifle (as a rifle grenade) or a grenade launcher. A modern hand grenade g ...
s, structures, and the like. The sand crush te
and
Trauzl lead block test are commonly used to determine the relative brisance in comparison to
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
A piston is a component of reciprocating engines, reciprocating pumps, gas compressors, hydraulic cylinders and pneumatic cylinders, among other similar mechanisms. It is the moving component that is contained by a cylinder and is made gas- ...
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
carburetted fuel/air mixes in vehicle piston engines, or
nitrocellulose fibres or grains of controlled textures in
firearm cartridges.
For certain types of
blasting, such as for
quarrying
A quarry is a type of open-pit mine in which dimension stone, rock, construction aggregate, riprap, sand, gravel, or slate is excavated from the ground. The operation of quarries is regulated in some jurisdictions to reduce their e ...
slate
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic ro ...
, in which the objective is to loosen the product from surrounding rock with as little damage as possible, one needs no more brisance than is necessary to split off the desired product profitably, without unacceptable waste. For this purpose
blasting powder of ''low'' brisance is necessary.
[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]
In shattering hard rock or military defences, brisance generally is necessary, so
high explosive
An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An e ...
s with extremely high
detonation velocity are used as far as is practical.
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.
Notably brisant explosives
One of the most brisant of the conventional explosives is cyclotrimethylene trinitramine (also known as
RDX or Hexogen). RDX is the explosive agent in the plastic explosive commonly known as
C-4, constituting 91% RDX by mass.
See also
*
Relative effectiveness factor
*
Table of explosive detonation velocities This is a compilation of published detonation velocities for various high explosive compounds. Detonation velocity is the speed with which the detonation shock wave travels through the explosive. It is a key, directly measurable indicator of explos ...
References
* A. Bailey & S.G. Murray, ''Explosives, Propellants & Pyrotechnics'', Brassey's (UK) Ltd., London, 1989.
Explosives
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