Defect identification in thick porous and wavy composites with hybrid use of ultrasound non-reciprocity and scattering

Diverse defects in thick composites were characterized using through transmission inspection based on ultrasound non-reciprocity and scattering. Simulations were conducted using OnScale® to reveal wave interactions with fiber waviness and voids of varying sizes at different positions. To validate the numerical predictions, two phased array probes were used to capture two sets of transmitted signals by reversing the excitation and reception sequence on three different samples: porous non-wavy, wavy, and porous wavy composites. Both voids and fiber waviness were found to induce reductions in the transmitted signal amplitudes due to wave scattering. At an optimized frequency, voids do not introduce time-of-flight differences, while fiber waviness causes measurable differences between the two transmitted signals due to direction-dependent frequency filters in the wavy region. Therefore, with the hybrid use of wave scattering and non-reciprocity, a promising solution for ultrasonic defect identification in thick porous and wavy composites was proposed.