Optimization of Bifrequential Pump Excitation Parameters by Genetic Algorithm in Nonlinear Vibro Acoustic Wave Modulation Technique
Résumé
The nonlinear Vibro-Acoustic wave Modulation (VAM) is a widely used technique in nonlinear nondestructive testing. Many research, in this area, are devoted to find the best combination of the excitation parameters, especially the right frequencies to the optimization of the damage detection sensitivity. In a previous study, we have proposed a novel method using the optimal command principle for a VAM system. Indeed, this method has permitted to find automatically the best pump frequency maximizing the nonlinear modulation (NM) effects in a multiple scattering sample. The cost function to be optimized thanks to the pump wave frequency is the correlation coefficient (CC) between a reference output signal without pump and an output modulated probe signal with the presence of the pump wave. In the present work, we aim to improve the nonlinear damage detection by exciting simultaneously two resonance modes of the medium. We consider a new excitation waveform for the pump wave, composed by the sum of 2 frequencies, instead of a monochromatic sine wave.
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