Improved ballistic limit equations for high-speed non-aluminum projectiles impacting aluminum dual-wall spacecraft systems

Abstract

One of the major design considerations of earth-orbiting spacecraft is the damage that might occur from an impact by a micrometeoroid or orbital debris particle. Ballistic limit equations (BLEs), which predict the response of spacecraft components under impact, are one of the key components of any micrometeoroid / orbital debris risk assessment calculation. However, given that a limited number of BLEs have been developed, analysts will sometimes use a BLE to assess the impact projectile made of a material that was not used in the development of that BLE. This paper presents the results of a two-part study that focused non-aluminum projectiles impacting aluminum dual-wall structures. In the first, results from high-speed impact tests using non-aluminum projectiles were compared against the predictions of a commonly used dual-wall BLE. In nearly all cases, this BLE was found not to work sufficiently well in predicting the high-speed impact response of non-aluminum projectiles. In the second, the dual-wall BLE was modified to more correctly predict the response of such wall systems to the high-speed impact of non-aluminum projectiles. This modified BLE was found to be much improved in predicting whether or not a high-speed non-aluminum projectile would perforate a dual-wall system.