Research on the Optimal Guided Wave Modes for the Detection of Delamination Defects

Carbon fiber composite has good material properties, but it is easy to cause defects during the process of preparation and performance. Delamination is one of the main forms of failure, which directly affects the safety of the material. Due to the dispersion and multimodality of ultrasonic guided waves, it is necessary to select sensitive modes for defect detection. In this paper, firstly, the dispersion curve and wave structures are calculated by semi analytical finite element method. Then the finite element simulation model in the frequency domain is established by COMSOL. The mode-frequency points with better detection effect are selected by analyzing the displacement changes, and the frequency sweep experiment is carried out to verify the simulation result. The result shows that mode 4 at 480kHz is suitable for the detection and identification of the delamination defects with different sizes.