secondary fragment

secondary fragment [′sek·ən‚der·ē ′frag·mənt]

(ordnance)

Secondary fragmentation resulting from either breakup of controlled or uncontrolled fragments upon impact or from the creation of fragments from the target material when it is impacted by a projectile; an example is the spalling of armor plate when it is pierced by armor-piercing shot; the fragments or spalls are broken off the back of the plate and become significant kill mechanisms within the armored enclosure.