Shock Testing of Pyrotechnic Actuators

Abstract : A primary task of the Advanced Munitions Concepts Branch (AMCB), Weapons and Materials Research Directorate, U.S. Army Research Laboratory, is to conceive unique munitions for tomorrow's weapons systems. Some of this design work has been focused on improving the accuracy of the existing stockpile of artillery projectiles and mortars. One of the critical constraints was to improve the existing stockpile of projectiles without requiring modifications. One approach has been to provide improved range control through modification of the fuze or to add a module that would fit between the fuze and the projectile body. These designs entail mechanisms that must survive 15,000 g's of set-back forces attributable to the cannon and mortar launch. If the projectile is spin stabilized, the projectile can experience 150,000 rad/s2 angular acceleration and a maximum spin rate of 300 Hz. Some of the mechanisms use an off-the-shelf actuator as an integral part of a locking mechanism. The locking mechanism, although different from one design to another, is required to keep control surfaces from deploying until the desired time in flight. The volume constraints, power budget, and possible loading conditions require the actuator to be very small, rugged, and powerful without using much electrical energy. Pyrotechnic-actuated devices, which can produce a pushing or withdrawing type of linear motion, are desired. These devices are appropriately small, and they require a small amount of power to function and produce a translation with substantial force. This report focuses on the 1MT262 retractable actuator and the 1MT172 micro-miniature piston actuator (MMPA), which are produced by Eagle-Picher Industries, Inc. Testing performed on these actuators includes shock testing to 17,000 g's, spin rate testing at 180 cycles per second, and an actual firing from an artillery cannon.