Toward Ultrasonic Tunable Ultra-Damping Metamaterials
Abstract
Intent of the research was to develop metamaterials with large attenuation capacities in a targeted field of frequencies, reducing the size of the resonators from the centimeter-level used in audible frequencies to microresonators able to function at ultrasonic frequencies, focusing on two approaches. The core-shell approach aimed to construct objects composed of a hard core showing a high density contrast with its surrounding elastic soft shell, the result embedded in a hard matrix. The second ( resonant-emulsion ) approach aimed at fabricating a material in which the incoming wave exhibits a Mie resonance with the inclusions due to the sound velocity contrast between the inclusions and surrounding matrix. For efficiency we focused on the resonant-emulsion approach, fabricating a soft material composed of oil emulsion droplets suspended in a liquid water-based gel, allowing us to vary the average size and droplet volume fraction in the material. Applying a wave frequency to this material indeed showed variable attenuation at different wavelengths. Varying the droplet diameters allowed polydispersity in the material, reducing the individual scattering peaks and applying the attenuation coefficient to a broader range of frequencies. By doping the material with ferrofluid we hoped to specifically tune the local Mie resonance frequencies to set ultradamping at particular frequencies (for adaptive filters and acoustic mirrors or other applications), and research bifurcated into synthesis of fluorinated ferrofluid, and acoustic measurements of the obtained material. Once the ferrofluid was synthesized, application of the magnetic field elongated the droplets, shifting resonance peaks to higher frequencies, and this attenuation strongly changes from one geometry to another (whether droplets were elongated perpendicular or parallel to the arriving waves). Research now looks to synthesize and investigate materials for more intense scattering such as silicon polymers.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 06, 2014
- Accession Number
- ADA627211
Entities
People
- A. Aradian
- B. Mascaro
- C. Aristegui
- J. Leng
- K. Zimny
- O. Poncelet
- O. Sandre
- Oliver Mondain-monval
- T. Brunet
Organizations
- National Center for Scientific Research