Air-coupled Lamb Waves Imaging for Impact Damage of CFRP Plates Based on the Time Reversal Damage Index

In order to realize the in-service inspection of aircraft carbon fiber reinforced plastics (CFRP) plates, the same side air-coupled ultrasonic lamb wave feature imaging detection method was used to detect the defects, The D-scan of the A0 mode Lamb waves, which were generated by noncontact air-coupled ultrasonic transducers on the same side of plates, was used to test the impact damage defects. Then, the time reversal damage index was introduced to characterize the impact damage of the CFRP plates. Combining with the probability damage imaging algorithm, the DI data of different scanning paths were regarded as feature values of reconstructed image. The lamb wave image which could display the size and location of the impact damage was acquired by the imaging fusion. The results showed that the lamb wave image based on time reversal can not only represent the position and size of the damage defect, but also can significantly improve the test efficiency by avoiding the selection of the reference signal and reducing the number of scaning steps.