Application of Digital Shearography and Active Thermography Methods in the Inspection of Internal Defects in Carbon Fiber-Reinforced Plastics

Selecting a proper method for inspecting particular materials is an imperative challenge in the nondestructive testing (NDT) field. In this regard, comparing different techniques to reach the best defect detection efficiency is of great importance. Digital shearography and active thermography are among the new NDT techniques providing many advantages such as full-field, noncontact, accurate and high-speed inspection. In this paper, both methods are employed to be compared in the detection of subsurface defects in carbon fiber-reinforced plastics (CFRPs). In this respect, several CFRP specimens with artificial defects, including delamination and cracks with various depths and sizes, were prepared. After conducting the relevant experiments, the results revealed that both methods are efficient in NDT of CFRPs. Nevertheless, active thermography indicated superior performance in the inspection of delamination by detecting deeper defects. Shearography showed a better performance in the case of cracks and short defects. However, shearography required more test preparation and a longer heating time.