Rigid-body metamaterials for sound absorption and manipulation Seminar
- Time:
- 16:00
- Date:
- 2 May 2017
- Venue:
- Building 13 Room 3017
For more information regarding this seminar, please email Rameen Mustafa at R.Mustafa@soton.ac.uk .
Event details
We present some recent acoustic metamaterial topics of experimental study at Exeter.
These will include acoustic metamaterial absorbers, comprised of only rigid metal and air, which gives rise to near unity absorption of airborne sound on resonance. The structures are typically simple, easily fabricated and robust: one particular example comprising a perforated metal plate separated from a rigid wall by a deeply subwavelength channel of air, is an ideal candidate for a sound absorbing panel. The strong absorption in the system is attributed to the thermo-viscous losses arising from a sound wave guided between the plate and the wall, defining the subwavelength channel. In the second part of this talk, we explore a trapped acoustic modes on surface geometries, such as meandering grooves and arrays of holes. Their dispersion are fully characterised and we illustrate the potential for manipulating sound propagation by the simple use of patterned rigid surfaces.
Speaker information
Alastair Hibbins , University of Exeter. Having gained a PhD in 2000 (supervised by Prof Roy Sambles FRS), Alastair undertook post doctoral positions at Exeter before being awarded a prestigious 5-year EPSRC Fellowship to study ‘a wide range of photonic microstructured devices for use at microwave frequencies’ in 2004. He published a paper in Science, ‘Experimental Verification of Designer Surface Plasmons’, which set up the groundwork on which many subsequent studies were based. In 2010, he led the Exeter part of the EPSRC programme grant ‘The Quest for Ultimate Electromagnetics using Spatial Transformations’, which further corroborated the direction of the microwave aspect of his research into themes associated with surface waves, the innovative design of novel ‘meta-atoms’, and three dimensional metamaterial structures. At the same time, a combination of scientific curiosity and strong interest from industry led to the development of an acoustic metamaterials strand to his research, focussing on making analogies with electromagnetism, and which now receives funding from DSTL, Thales and QinetiQ. In 2017, he is a co-director of Exeter's EPSRC Centre for Doctoral Training in Metamaterials, and deputy director of the EPSRC Grand Challenge 'SYMETA'. His vision is to exploit the synergies in metamaterial concepts between the regimes of microwave and acoustics, and has recently received funding to extend this to study metamaterial-concepts for fluid flow. His team are addressing critical questions concerning novel characteristics of materials and surfaces (e.g. slow energy propagating, negative index, impedance matching, subwavelength resonators, scattering enhancement, coupled resonant systems etc.), the fundamental operational range of metamaterials, while also pursuing practical implementation of the science into application.