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

Menglong Liu,Cliff Lissenden,Kai Wang,Fangsen Cui,Qiang Wang,Renrong Long,Zhongqing Su,Qingming Zhang

doi:10.3390/ma10050547

Abstract

Hypervelocity impact (HVI), ubiquitous in low Earth orbit with an impacting velocity in excess of 1 km/s, poses an immense threat to the safety of orbiting spacecraft. Upon penetration of the outer shielding layer of a typical two-layer shielding system, the shattered projectile, together with the jetted materials of the outer shielding material, subsequently impinge the inner shielding layer, to which pitting damage is introduced. The pitting damage includes numerous craters and cracks disorderedly scattered over a wide region. Targeting the quantitative evaluation of this sort of damage (multitudinous damage within a singular inspection region), a characterization strategy, associating linear with nonlinear features of guided ultrasonic waves, is developed. Linear-wise, changes in the signal features in the time domain (e.g., time-of-flight and energy dissipation) are extracted, for detecting gross damage whose characteristic dimensions are comparable to the wavelength of the probing wave; nonlinear-wise, changes in the signal features in the frequency domain (e.g., second harmonic generation), which are proven to be more sensitive than their linear counterparts to small-scale damage, are explored to characterize HVI-induced pitting damage scattered in the inner layer. A numerical simulation, supplemented with experimental validation, quantitatively reveals the accumulation of nonlinearity of the guided waves when the waves traverse the pitting damage, based on which linear and nonlinear damage indices are proposed. A path-based rapid imaging algorithm, in conjunction with the use of the developed linear and nonlinear indices, is developed, whereby the HVI-induced pitting damage is characterized in images in terms of the probability of occurrence.

Highlights

Numerous man-made spacecraft co-exist with innumerable meteoroids and orbital debris (MOD) particles in low Earth orbit
The correction of diffraction based on the analytical 3-D nonlinear Raleigh wave is available [34], the analytical solution of the nonlinear
The correction of diffraction based on the analytical 3-D nonlinear Raleigh wave is available [34], the analytical solution of the nonlinear Lamb wave taking the diffraction into account is yet to be developed

Summary

Introduction

Numerous man-made spacecraft (e.g., satellites, space stations, and shuttles) co-exist with innumerable meteoroids and orbital debris (MOD) particles in low Earth orbit. Materials 2017, 10, 547 spacecraft, can severely jeopardize the integrity of the spacecraft [1,2]. This sort of impact is commonly referred to as a “hypervelocity impact” (HVI), a scenario typically involving an impacting velocity in excess of 1 km/s. HVI is ubiquitous in space, as evidenced by numerous impact lesions seen on spacecraft after every flight mission. Addressing such significance, HVI has received a great deal of attention since the 1950s when humans began extensive exploration into outer space [3].

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