Characterization of Damage in Shielding Structures of Space Vehicles under Hypervelocity Impact

The cluttering of meteoroids and orbital debris (MODs) on the low earth orbit poses a vast threat to the safety of orbiting space vehicles. Collision between MODs and space structures, a.k.a., hypervelocity impact (HVI), can result in catastrophic consequences, due to the extremely high velocity (of the order of km/s) between MODs and space vehicles. An active linear/nonlinear guided-wave-based approach for characterizing HVI-induced damage in a two-layer aluminum shielding structure (comprised of inner and outer layers) was developed. Aluminum spheres were discharged using a two-stage light gas gun, at an impact speed ∼6 km/s to introduce HVI to the outer shielding layer. Compared to low-velocity impact (LVI), the instant large kinetic energy bore by HVI makes the outer plate penetrated, and then the generated debris cloud furthers impacts the inner plate, with numerous craters left. A hybrid active linear/nonlinear guided-ultrasonic-wave-based damage detection algorithm was proposed, to evaluate the damage on the inner layer. Combining the ease in implementation of the linear approach and the high sensitivity and baseline-free of the nonlinear approach to small damage, the active hybrid algorithm, offers a solution to the in situ perception and monitoring of HVI-induced damage to space vehicles.