Pure SH0 wave tomography for delamination detection in aerospace composites

This paper presents an ultrasonic guided wave tomography for detecting and sizing delaminations in composites using pure shear horizontal (SH) wave. In this method, pure SH0 wave excitation was achieved using the adjustable angle beam transducers (ABT) in quasi-isotropic composite plates. First, a 3-mm quasi-isotropic composite plate with simulated delaminations by Teflon inserts was manufactured. Then, the ABT tuning angle of SH0 mode was calculated from the theoretical phase-velocity dispersion curve based on Snell's law. Experiments were conducted on the 3-mm quasi-isotropic composite plate for pure SH0 wave excitation and delamination detection. It was found that a significant decrease in the signal amplitude was observed due to the delaminations. Finally, a linear scanning approach in 0 degrees and 90 degrees directions was conducted to cover the whole delamination area. The collected signals were used to visualize the damage through damage imaging methods. SH0 wave tomography based on the reconstruction algorithm for probabilistic inspection of defects (RAPID) was applied for delamination detection and characterization. The experimental results show that the SH0 wave tomography has a good performance for delamination detection, size estimation, and localization in aerospace composites.