| Abstract: | Manmade debris and natural meteoroids, travelling in the Low Earth Orbit at a speed of several kilometers per second, pose a severe safety concern to the spacecraft in service through the HyperVelocity Impact (HVI). To address this issue, an investigation of shock Acoustic Emission (AE) waves induced by HVI to a downscaled two-layer Whipple shielding structure is performed, to realize a quantitative damage evaluation. Firstly a hybrid numerical model integrating smooth-particle hydrodynamics and finite element is built to obtain the wave response. The projectiles, with various impact velocities and directions, are modelled to impact the shielding structure with different thicknesses. Then experimental validation is carried out with built-in miniaturized piezoelectric sensors to in situ sense the HVI-induced AE waves. A quantitative agreement is obtained between numerical and experimental results, demonstrating the correctness of the hybrid model and facilitating the explanation of obtained AE signals in experiment. Based on the understanding of HVI-induced wave components, assessment of the damage severity, i.e., whether the outer shielding layer is perforated or not, is performed using the energy ratio between the regions of “high frequency” and “low frequency” in the acquired AE signals. Lastly, the direct-arrival fundamental symmetric wave mode is isolated from each sensing signal to be input into an enhanced delay-and-sum algorithm, which visualizes HVI spots accurately and instantaneously with different sensor network configuration. All these works demonstrate the potential of quantitative, in situ, and real time HVI monitoring using miniaturized piezoelectric sensor network. |
