Grooved body of a Second World War-era U.S. Mk 2 grenade. The grooves covering the exterior of the grenade are used to aid in the throwing and gripping of the grenade.
Diagram of S-mine in the delivery of steel ball shrapnel.
Fragmentation is the process by which the casing of an artillery shell, bomb, grenade, etc. is shattered by the detonating high explosive (HE) filling. The correct technical terminology for these casing pieces is fragments (sometimes shortened to frags), although shards or splinters can be used for non-preformed fragments. The fragments can also be preformed and of various shapes (spheres, cubes, etc.) and sizes. Preformed fragments are normally held rigidly within some form of matrix or body until the HE filling is detonated. The resulting high velocity fragments produced by either method are the main lethality mechanisms of these weapon. The word shrapnel is often used to describe these fragments. The word shrapnel originally referred to a specific type of shell, the shrapnel shell, which doesn't rely on a high explosive to shatter the casing. A World War I-era shrapnel shell uses a small (black) powder charge in the base of the shell to expel the lead or iron shot at a relatively low velocity, 200 m/s (700 ft/s). The explosion, at a predetermined time and height above the target area, is controlled by a time fuze. Due to the low velocity of the shot when compared with fragments produced by a detonating HE munition, it is only really effective against human targets, not materiel or armor.
The original article can be found at Fragmentation (weaponry) and the edit history here.