Comparison of laser ultrasonic techniques and damage visualization using reverberation for thick composite inspection

Abstract

Increasing use of thick composite structures in many fields of work including aerospace industry calls out the need for appropriate inspection to ensure structural integrity. Among many nondestructive testing (NDT) techniques, laser ultrasonic testing presents very accurate inspection result with high resolution in addition to its merit as a non-contact method. In this study, three laser ultrasonic techniques are compared by inspecting 25t CFRP to determine the most appropriate inspection technique for thick, curved composite structure. Then, damage visualization technique called ultrasonic energy mapping was integrated with the effect of reverberation induced by high pulse repetition frequency and it was verified by comparison with through-transmission inspection. Finally, it was successfully applied for damage visualization of thick, curved composite structure.