Excitation frequency optimisation to enhance harmonics backscattered by a nonlinear medium

Volodymyr Gatsa (1, 2) , Sébastien Ménigot (1, 2) , Vincent Tournat (2)

1 GSII - ESEO-GSII
2 LAUM - Laboratoire d'Acoustique de l'Université du Mans

In non-destructive evaluation (NDE), ultrasound plays an important role in physical structure characterization. However, by application of such methods, a little crack cannot be easily detected due to sub-band noises or attenuation in the material. By using of high excitation power source, cracks in the material resonate and generate nonlinear effects on the propagation of the acoustic waves. This feature of the crack response is used for its study by nonlinear NDE methods. The proposed application is the optimization of the excitation parameter using the feedback of the measured system. Energies of harmonic components of the received signal were taken as cost functions. The derivative-free algorithm was applied to find the optimal excitation parameter which gives the maximum of a cost function. The optimization has been done for the 2D sample of the duralumin plate simulated by a pseudo-spectral wave solver. The optimal values of excitation frequencies for different reference stresses have been found. For reference stress of 800 kPa, a gain of 5 dB can be reached in comparison with excitation at the central frequency of the transducer. The importance of an automatic frequency finding was considered to be more privileged compared to the empirical frequency scanning.

Mots clés: nonlinear ultrasound; NDT - Non destructive testing

Domaines: Acoustique [physics.class-ph]; Traitement du signal et de l'image [eess.SP]

Volodymyr Gatsa, Sébastien Ménigot, Vincent Tournat. Excitation frequency optimisation to enhance harmonics backscattered by a nonlinear medium. Forum Acusticum 2020, Société Française d'acoustique; European Acoustics Association, Dec 2020, Lyon (en ligne), France. pp.31-35, ⟨10.48465/fa.2020.0493⟩. ⟨hal-03045539⟩