Abstract
The ultrasonic wave transmission behavior through a unidirectional CFRP laminate with spring-type interlayer interfaces immersed in water is investigated using the stiffness-matrix approach. The amplitude transmission coefficient is shown to be influenced by the frequency, angle of incidence, and interlayer interfacial stiffnesses. Using Floquet's theorem, the band structure of Floquet wave propagating in the infinitely laminated structure is computed and compared to the transmission coefficient of the immersed laminate with finite number of plies. This reveals that the band-gaps of Floquet waves are in good agreement with the region where the transmission coefficient falls to a low level, indicating that the band-gaps do appear even in the laminate of finite thickness.
