Brisance is a characteristic of explosive materials (usually high explosives, but not always) and is defined as 'shattering power.' In addition to the total energy released by an explosive, its brisance is a measure of how quickly the blast wave from detonating the explosive in question reaches maximum pressure. The higher the brisance (from the French briser, 'to break') the more effective the explosive will generally be at shattering or fragmenting substances in close proximity.
This is useful information for determining the most effective substances to use as propellants, bursting charges or in demolitions. For example, a propellant should be a high power but low brisance explosive, to ensure that pressures inside a cartridge, shell or chamber rise steadily and slowly enough to permit the projectile to leave the gun without damage. However, the filler for a shell, grenade or bomb should be high brisance if fragmentation is desired.
Brisance is measured by instrumenting test explosions of substances with metal or sand crush gauges. The deformation of these gauges can be compared (sort of like how CUP pressure is measured in firearms) to determine the brisance of the explosive.
(IN 5 27/30)