Acoustic Characterization of an Aluminum Plate with Corrugated Surface

In this paper, the propagation of Lamb waves in an aluminum plate with a controlled roughness is studied. The roughness is located in a limited zone of the plate. The power spectral density (PSD) of the roughness exhibits three main peaks. Theoretically, a phonon relation can be written, linking the wavenumber of an incident Lamb mode, the wavenumber of a reflected converted Lamb mode and the phonon related to a peak of the DSP. Experimentally, an incident Lamb mode is excited on the flat side and its interaction with the roughness is studied. Reflected converted waves and the transmission of the incident Lamb mode are observed. Experimental results show the link between the main spatial frequencies included in the roughness and the wavenumber of the converted modes, as predicted theoretically.