In
explosives engineering
Explosives engineering is the field of science and engineering which is related to examining the behavior and usage of explosive materials.
Topics
Some of the topics that explosives engineers study, research, and work on include:
* Development ...
, 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 ...
, 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 s ...
pressure.
Practical uses
Brisance is of practical importance for determining the effectiveness of an explosion in
fragmenting shells,
bomb casings,
grenades, 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
Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...
(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
carburetted fuel/air mixes in vehicle piston engines, or
nitrocellulose
Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...
fibres or grains of controlled textures in
firearm cartridge
Cartridge may refer to:
Objects
* Cartridge (firearms), a type of modern ammunition
* ROM cartridge, a removable component in an electronic device
* Cartridge (respirator), a type of filter used in respirators
Other uses
* Cartridge (surname), a ...
s.
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 envir ...
slate, 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
Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). Th ...
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 ...
s with extremely high
detonation velocity
Explosive velocity, also known as detonation velocity or velocity of detonation (VoD), is the velocity at which the shock wave front travels through a detonated explosive. Explosive velocities are always faster than the local speed of sound in t ...
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
TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a ...
*
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 explosi ...
References
* A. Bailey & S.G. Murray, ''Explosives, Propellants & Pyrotechnics'', Brassey's (UK) Ltd., London, 1989.
Explosives
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