Experimental Ultrasound Transmission through Fluid-Solid and Air-Solid Phononic Plates.

Area of Science:

• Acoustics
• Materials Science
• Solid Mechanics

Background:

• Phononic crystals exhibit unique wave manipulation properties.
• Ultrasonic wave propagation in solids is influenced by material properties and surrounding media.
• Understanding transmission characteristics is crucial for designing acoustic devices.

Purpose of the Study:

• To investigate and compare underwater ultrasonic transmission through fluid-solid and air-solid phononic brass plates.
• To elucidate the underlying physical mechanisms governing wave propagation in these distinct phononic structures.
• To identify how differences in medium impedance affect phononic plate behavior.

Main Methods:

• Experimental setup for underwater ultrasonic transmission measurements.
• Fabrication of identical brass phononic plates for both fluid-solid and air-solid configurations.
• Analysis of transmission spectra and comparison between the two experimental conditions.

Main Results:

• Significant differences in transmission behavior were observed between fluid-solid and air-solid phononic plates.
• Fluid-solid plate properties are dominated by Fabry-Perot resonances, Wood anomalies, and Lamb modes.
• In air-solid plates, Fabry-Perot resonance is attenuated; surface mode coupling becomes prominent.

Conclusions:

• The surrounding medium (fluid vs. air) critically alters the acoustic response of phononic plates.
• Impedance mismatch in air-solid systems leads to distinct wave phenomena compared to fluid-solid systems.
• This research highlights the importance of medium-dependent effects in phononic crystal applications.