Study on guided wave propagation in a water loaded plate with wavenumber analysis techniques

Abstract

Guided waves have been increasingly used for long range ultrasonic nondestructive evaluation (NDE) and structural health monitoring (SHM) in thin-wall structures. When the structure is in contact with liquid such as water, the wave propagation will be changed due to the boundary condition change. In this paper, we study the guided wave propagation in a water loaded plate with wavenumber analyses. Experimentally, a surface mounted PZT wafer is used to generate the waves and a non-contact laser Doppler vibrometer (SLDV) is used to measure the time-space wavefield which contains a wealth of information regarding the propagating waves. Characteristic features of the propagating guided waves in the water loaded plate are acquired with three different wavenumber analysis techniques: (i) frequency-wavenumber analysis, (ii) space-frequency-wavenumber analysis, and (iii) time-space-frequency-wavenumber analysis. Using the wavenumber representations, various wave modes such as A0, S0 as well as the quasi-Scholte modes specific in water-solid interface are readily recognized. Mode conversions and boundary reflections are also identified at the interface where air medium changes to water. The results have shown the effectiveness of wavenumber analysis techniques in the study of wave propagation from the perspective of wavenumber domain.