Pyrotechnic fastener
From Wikipedia, the free encyclopedia
A pyrotechnic fastener (also called an explosive bolt) is a fastener, usually a nut or bolt, that incorporates a pyrotechnic charge that can be initiated by a remote command. Explosive charges embedded within the bolts and typically activated by an electric current instantly break the bolt into two or three pieces. The bolt is typically scored around its circumference at the point(s) where the severance should occur. Upon detonation a select part of the fastener rapidly disassembles without producing any shrapnel or fragments, freeing the mated units from each other. They are often used in space applications to ensure separation between rocket stages, since they are lighter and far more reliable than mechanical latches.
Often the term "explosive bolt" is used to refer to pyrotechnic fasteners in general. For example it is often stated that the Space Shuttle is held to the launch pad with explosive bolts but it is actually the large nuts that each contain two pyrotechnic charges that split the nut into two pieces.
More recent developments have utilized pulsed laser diodes to detonate initiators through fiber-optic cables which subsequently fire the main charge.
