Numerical and experimental investigations on mode conversion of guided waves in partially immersed plates

Abstract

This paper numerically and experimentally investigates guided wave propagation in a steel plate with one side partly exposed to water. The fundamental anti-symmetric Lamb wave (A₀) is excited on the dry plate section and travels to the water-immersed plate section, where the generated A₀ wave is mode converted to quasi-Scholte (QS) wave. The results demonstrate that the energy of QS wave converted by A₀ wave decreases when the excitation frequency increases. In addition, it is revealed that the guided wave energy can shift in the frequency domain if the phase velocity of the incident A₀ wave is larger than the sound speed of water. The frequency shift phenomenon should be noticed in practical applications because the behaviors of guided waves vary with frequency. Finally, discussions are provided on the frequency selection for exciting guided waves to detect damage on partially immersed structures and assess liquid properties.