Phased array ultrasonic imaging of multilayered complex structures using extended non-stationary phase shift migration with circular statistical vector weighting

Power and aerospace industries widely utilised multilayered complex structures. However, ultrasonic phased array inspection of internal defects in such components remains a significant challenge due to the combined effects of multiple media and complex interfacial boundaries. This paper proposes an extended non-stationary phase shift method (ENPSM), which applies circular statistical vector factor (CSVF) weighting algorithm. The instantaneous phase of full matrix capture (FMC) data is obtained via the Hilbert transform, and cosine and sine components are used to construct CSVF in the frequency domain to evaluate phase consistency. The emission and reception wavefields were extended and extrapolated using a wave velocity distribution window. This process enabled the reconstruction of both the transmitted and received wavefields, including their cosine and sine components. The cross-correlation imaging condition is finally applied to convert the wavefields into a defect image. Experiments show improved performance over total focusing method (TFM), with 2.45 fold increase in global contrast index (CG), 73.66% array performance indicator (API) reduction, and 22.98% lower computation time.