Keynote 3 Membrane-type Acoustic Metamaterials: Reflection and Absorption of the Low Frequency Sound
Date/Time Thursday, 2 May 2013 / 11:20 – 12:00
Venue Riverfront Ballroom

Prof. Ping SHENG
The Hongkong University of Science and Technology, Hong Kong

Ping Sheng is the William Mong Chair Professor of Nanoscience at the Department of Physics, Hong Kong University of Science and Technology. He obtained his BSc in Physics from Caltech in 1967 and PhD in Physics from Princeton in 1971. He joined HKUST in 1994 after six years at the Sarnoff Research Lab in Princeton as a member of technical staff, and fifteen years at the Exxon Corporate Research Lab at Clinton, NJ, as a senior research associate. His current research interests include superconductivity in carbon nanotubes, acoustic metamaterials, giant electrorheological fluids, and hydrodynamic boundary condition at the fluid-solid interface.

We show that thin rubber membranes can not only totally reflect low frequency sound at frequencies that are tunable by using attached weights [1], but also be designed to absorb up to 99% of the incident sound energy [2]. At the reflection frequencies the effective mass, defined by averaged force divided by averaged acceleration, can be positive or negative infinite, whereas the strong absorption is shown to arise from the very high energy density caused by the concentration of curvature energy at the perimeters of the attached weights. Detailed measurements by laser vibrometer as well as transmission spectra are in excellent agreement with theoretical predictions.