Lamb wave propagation on a unidirectional CFRP plate: comparison of FEM simulations, experiments, and analytical calculations

Carbon fiber-reinforced plastics (CFRPs) are widely used in recreational products and industrial components. Ultrasound is a powerful tool to ensure the safety of CFRP structures, but the ultrasonic velocity on CFRP depends on the frequency and direction of propagation. Understanding ultrasonic propagation is the key to its proper application to CFRP structures. In the present work, experiments, 3D FEM simulations, and theoretical analyses were performed to investigate Lamb wave propagation on CFRP plates. The simulation and experimental results agreed well, proving that the FEM simulation results were reliable. On the basis of this reliability, further results were obtained for various fd values. The S0 mode's group velocity was considerably affected by the propagation direction, but the A0 mode exhibited minimal dependence. In addition, unexpected waves were observed in the simulation and identified as the SH0 mode. A new approach for determining the theoretical group velocity was also presented.