Adaptive time-reversal method for delamination detection of composite plates based on reconstruction algorithm for probabilistic inspection of defects

In this study, delamination in composite plates was detected by combining a baseline-free detection method based on a time-reversal method with a damage-imaging algorithm based on the reconstruction algorithm for probabilistic inspection of defects. A new adaptive time-reversal method (ATRM) for calculating the damage index values was proposed through the local adaptive analysis of the time-reversal signals of Lamb waves. The time-reversed signals were obtained by determining the maximum correlation between the forward path response and excitation signals. The forward path and time-reversal signals were intercepted using local optimal correlation coefficients to compensate for the peak offset errors that occurred during Lamb wave propagation. Multiple optimal adaptive decompositions were used to eliminate the interference of reflected waves in the forward path. The feasibility of the proposed method was verified numerically using finite element simulations, and was quantitatively compared with that of the conventional time-reversal method. Experimental studies using actual composite plates further validated the proposed method. The influence of the damage location on the performance of the proposed method was also investigated. The results show that the ATRM method significantly improved the temporal reversibility and obtained the optimal global similarity, making it more accurate and reliable for localising the delamination defects in composite plates compared with existing time reversal-based methods.