Increasing the modal density in plates for mono-element focusing in air.
Acoustic focusing experiments usually require large arrays of transducers. It has been shown by Etaix et al. [J. Acoust. Soc. Am. 131, 395-399 (2012)] that the use of a cavity allows reducing this number of transducers. This paper presents experiments with Duralumin plates (the cavities) containing scatterers to improve the contrast of focusing. The use of a scatterer array in the plate allows increasing the modal density at given frequencies. The scatterers used are membranes and buttons that are manufactured in Duralumin plates. Their resonances are studied both experimentally and numerically. Such scatterers present the advantage of having a tunable frequency resonance, which allows controlling the frequencies at which the modal density increases. The dispersion relations of plates with scatterer array show high modal density at given frequencies. Finally acoustic focusing experiments in air, using these plates, are compared to the ones of simple duralumin plates demonstrating the improvement of contrast. Acoustic source localization is also realized using these plates.
Institut Langevin, Ecole Superieure de Physique et de Chimie Industrielles, ParisTech, CNRS Unité Mixte de Recherche 7587, 1 Rue Jussieu, 75005 Paris, France.
Nicolas
N
Etaix
Jerôme
J
Dubois
Mathias
M
Fink
Ros-Kiri
RK
Ing
D000162:Acoustics / Q000295:instrumentation*; D000388:Air; D003198:Computer Simulation; D004548:Elasticity; D004867:Equipment Design; D005583:Fourier Analysis; D008567:Membranes, Artificial; D008962:Models, Theoretical; D009038:Motion; D009716:Numerical Analysis, Computer-Assisted; D012542:Scattering, Radiation; D013016:Sound; D013018:Sound Spectrography; D013997:Time Factors; D014159:Transducers; D014732:Vibration
D008567:Membranes, Artificial