Acoustoelastic ultrasonic tomography for non-destructive cross-sectional stress imaging

Non-destructive characterization of internal stress distributions remains a key challenge for structural integrity evaluation. This study presents an acoustoelastic ultrasonic computed tomography framework for reconstructing cross-sectional axial stress fields from time-of-flight measurements. Stress-induced velocity perturbations are interpreted through an equivalent stress-dependent elastic representation, allowing time-of-flight differences to be treated as projection data for tomographic inversion. A fan-beam acquisition configuration is implemented to accommodate practical ultrasonic measurement geometries. The method is validated through coupled finite-element simulations and controlled experiments on a 6061-T6 aluminum disk subjected to three-point compression using a circular transducer array. Reconstructed stress maps successfully resolve multiple non-axisymmetric stress concentration regions with spatial distributions consistent with numerical predictions. Parametric analyses further demonstrate the influence of projection density and detector spacing on reconstruction fidelity. Results indicate that the proposed approach enables stable and repeatable stress imaging under laboratory conditions, providing a feasible pathway toward ultrasonic full-field stress evaluation for non-destructive testing applications.