Transient space-time surface waves characterization using Gabor analysis

Abstract

Laser ultrasonics allow the observation of transient surface waves along their propagation media and their interaction with encountered objects like cracks, holes, borders. In order to characterize and localize these transient aspects in the Space-Time-Wave number-Frequency domains, the 1D, 2D and 3D Gabor transforms are presented. The Gabor transform enables the identification of several properties of the local wavefronts such as their shape, wavelength, frequency, attenuation, group velocity and the full conversion sequence along propagation. The ability of local properties identification by Gabor transform is illustrated by two experimental studies: Lamb waves generated by an annular source on a circular quartz and Lamb wave interaction with a fluid droplet. In both cases, results obtained with Gabor transform enable ones to identify the observed local waves.

Investigation Of Bracings Transformations On Voboam Guitars: What Can Uncalibrated FEM Models Tell Us?

“…In addition, a better knowledge of the mechanical parameters of materials would help. Instead of using literature values, the resort to a non-destructive and in-situ technique [20] to properly measure the mechanical properties of the soundboard and the backboard could be used considering the ageing of the instruments. Finally, modal base matching used for the comparison of the instrument might be too specific to the structure: two instruments with slightly different structural modal bases could still have a similar perceived acoustic radiation.…”