Topological acoustics and geometric phase sensing for non-destructive localization and characterization of defects.

Ensuring structural reliability in aerospace and advanced manufacturing demands non-destructive evaluation (NDE) techniques that are both accurate and adaptable. We present a flexible framework based on geometric phase sensing, which captures topological shifts in acoustic fields to characterize internal defects. By integrating broadband excitation with remote sensing methods such as laser Doppler vibrometry, we demonstrate defect localization and tracking using a geometric phase change-index (GPC-I) and extend the method to quantitative pore structure analysis through global geometric phase measurements. Applied to additively manufactured Inconel 718 samples, our approach enables both spatial mapping of defect distributions and quantitative correlation with pore size, pore volume fraction, and pore clustering, as validated by micro-X-ray computed tomography. The method eliminates the need for prior material calibration, enabling real-time, model-free detection and microstructure evaluation under practical manufacturing constraints, offering a path toward scalable, high-fidelity structural health monitoring and quality assurance in complex manufacturing environments.