General Ballistic-Limit Equations for Whipple Shields Against Low- and High-Density Meteoroid Surrogates

Abstract Long-term reliability of habitable volumes requires knowing the onset of a perforation of a hull for crewed vehicles. Previous studies and models have been developed from ground-test data and rely on empirical extrapolations to higher speeds of orbital debris. These extrapolations are to less than twice the speed of ground-test data; therefore, these empirical extrapolations are assumed to be reasonable for many of the current operating vehicles in the orbital debris environment. This assumption may not hold up well for meteoroid impacts as they are expected to occur at impact speeds of 20 to 80 km/s, which is over ten times the impact speeds from the anchor data. Due to these significant extrapolations, it has been deemed important to try to find better tools for extrapolating from existing data than empirical models. To this end, numerical simulations are being performed of impacts into a variety of Whipple shield configurations to determine the threshold of detached spall and hole size in rear walls of double-wall Whipple shields at conditions representative of meteoroid impacts. From these simulations, ballistic-limit models as a function of shield type, projectile material and size, impact speed and obliquity, have been developed for empirical model evaluation and refinement. This work discusses the aspects of simulation model verification, simulated conditions, and empirical model evaluation.