Characterizing Hypervelocity Impact (HVI)-Induced Pitting Damage Using Active Guided Ultrasonic Waves: From Linear to...

Area of Science:

• Spacecraft engineering
• Materials science
• Non-destructive testing

Background:

• Hypervelocity impacts (HVIs) at over 1 km/s pose significant risks to spacecraft safety in low Earth orbit.
• Penetration of spacecraft shielding by HVIs creates complex pitting damage on inner layers, characterized by numerous craters and cracks.
• Quantitative evaluation of widespread, small-scale pitting damage is challenging with traditional methods.

Purpose of the Study:

• To develop a novel characterization strategy for quantitatively evaluating HVI-induced pitting damage on spacecraft inner shielding layers.
• To associate linear and nonlinear features of guided ultrasonic waves with different scales of damage.
• To create an imaging algorithm for visualizing HVI damage based on wave signal analysis.

Main Methods:

• Guided ultrasonic waves (GUWs) were employed, analyzing both linear (time-domain) and nonlinear (frequency-domain) signal features.
• Linear analysis focused on time-of-flight and energy dissipation for gross damage detection.
• Nonlinear analysis explored second harmonic generation for enhanced sensitivity to small-scale pitting damage.

Main Results:

• Numerical simulations and experimental validation demonstrated the accumulation of nonlinearity in GUWs traversing pitting damage.
• Linear and nonlinear damage indices were proposed based on observed signal changes.
• A path-based imaging algorithm successfully characterized HVI-induced pitting damage in terms of occurrence probability.

Conclusions:

• The developed strategy effectively characterizes HVI-induced pitting damage by integrating linear and nonlinear GUW features.
• Nonlinear wave phenomena offer superior sensitivity for detecting and evaluating small-scale damage.
• The proposed imaging algorithm provides a probabilistic map of damage, enhancing spacecraft structural health monitoring.