Ultrasonic Guided Wave in Aluminum -CFRP Multilayer Pipes

Damages in metal-CFRP multilayer pipes are potential threats to structural safety, leading to the necessity of nondestructive testing on them. As one of the most mainstream non-destructive testing methods, ultrasonic testing relies on the knowledge of wave characteristics, i.e. dispersive properties and wave structures. In this paper, an eigen-frequency method is proposed to efficiently and accurately analyze the wave characteristics in metal-CFRP multilayer pipes, with the aid of Floquet periodic boundary conditions. Experimentally, a non-contact laser ultrasonic system is established to measure the multi-modal dispersion curves in a broad frequency range. Results from the theoretical and experimental methods lay a firm foundation for damage detection in the metal-CFRP pipes, by using ultrasonic guided waves.