Energy compensation for ultrasonic imaging of carbon fiber-reinforced composite laminates using ray tracing

Abstract The inherent elastic anisotropy and multilayer structure of carbon fiber reinforced composites (CFRP) present substantial challenges in accurately determining ultrasonic travel time and lead to pronounced attenuation of ultrasonic signals, significantly constraining the applicability of the total focusing method (TFM). This paper proposes an energy attenuation measurement method and establishes the relationship between ultrasonic travel time and energy attenuation in CFRP laminates, enabling the compensation of deep-layer energy in TFM images. This modified TFM, termed energy compensation TFM (EC-TFM), was validated by imaging experiments on a 6.9 mm multidirectional CFRP laminate. The results demonstrate that the EC-TFM mesimulathod effectively compensates for deep-layer energy attenuation in ultrasonic images. Compared to the original TFM imaging results, the amplitude at defect locations is significantly enhanced, with a 47% increase observed for deep defects. Additionally, EC-TFM suppresses structural noise, improving SNR by 1.53 dB and 3.59 dB relative to TFM and ray-tracing TFM, respectively.