Research on microcrack detection methodology for aluminum skins using coda wave interferometry

Abstract To address the insufficient sensitivity of conventional ultrasonic testing techniques in detecting surface microcracks on aircraft skins, this study proposes a micro-damage detection method based on the principle of Coda Wave Interferometry (CWI). By establishing a multi-physics coupled micro-damage scattering model, high-precision extraction and quantitative characterization of coda wave signal features are realized. The results of theoretical analysis and experimental validation reveal that, under the condition of microcracks with varying sizes, the relative wave velocity variation of coda wave signals exhibits a significant linear correlation with damage dimensions. Through the establishment of such a mapping relationship, this method breaks through the near-surface resolution limitation of traditional ultrasonic testing techniques and enables quantitative detection of submillimeter/micrometer-scale surface microcracks.