Modeling Hypervelocity-Impact-Induced Shock Waves for Characterizing Orbital Debris-Produced Damage

Hypervelocity impact (HVI) is a scenario involving an impacting velocity in excess of 1 km/s. Ubiquitous in outer space, paradigms of HVI are typified by the collision between orbital debris and spacecraft. HVI features transient, localized, and extreme material deformation under which the induced acoustic emission (AE) signals present unique yet complex features. A dedicated modeling and numerical simulation approach, based on the three-dimensional smooth-particle hydrodynamics (SPH), was developed to gain an insight into characteristics of HVI-induced AE propagation. With the approach, both normal and oblique HVI scenarios were interrogated, and material failure in both cases was predicted. The coincidence in results between simulation and HVI experiment, as observed at a qualitative degree, has demonstrated the effectiveness of the modeling. Signal analysis shows that the shock wave converts to Lamb wave quickly as propagation from HVI spot, with the zeroth-order symmetric wave mode (S₀) (i.e., the first-arrival wave) dominating wave signal energy. S₀ is observed dispersive in a wide frequency range with majority of it below 1 MHz. In comparison, the antisymmetric wave mode distributes in a range below 200 kHz with a peak value at 30 kHz. S₀ was employed to pinpoint the location of HVI, using an enhanced delay-and-sum-based diagnostic imaging algorithm, which was validated by locating orbital debris-induced orifice in space structures, showing precise identification results.