Abstract:

The characteristics of the hypervelocity impact (HVI) acoustic emission (AE) S2 mode in aluminum plate is investigated with the aim of researching the relationship with the damage pattern. A variety of HVI AE signals in different cases are obtained by the numerical simulation, with the research object of an aluminum 5A06 single wall plate, 5mm in thickness. The S2 mode of the signal is extracted to analyze its features of amplitude, energy and frequency spectrum. Results indicate that the energy of the S2 mode has exponential decrease with increasing propagation distance, follows a rule of decreasing firstly and then increasing with increasing the projectile diameter and impact velocity respectively, and finally reaches its lowest point with the ballistic limit velocity and diameter of the projectile approximate to the thickness of the plate. The center frequency of the S2 mode decreases with increasing the diameter of the projectile, increases with increasing impact velocity, and moves to 1500 kHz with increasing the propagation distance. The frequency range whose wavelet coefficient of S2 mode is concave, is narrow down with increasing the impact velocity and diameter of the projectile, respectively. And on this basis, the diameter of the projectile can be speculated by the center frequency of S2 mode if the hold damage appears, and the impact velocity can be speculated by the frequency range whose wavelet coefficient of S2 mode is concave when the diameter of the projectile and propagation distance are known.

Key words: Space debris, Hypervelocity impact, Modal acoustic emission, Damage pattern recognition, Manned spaceflight