Description of field of research:

Acoustic metamaterials are engineered composite structures designed using distributions of inclusions in a host material to exhibit favourable acoustic properties. One specific design of an acoustic metamaterial composed of inclusions in soft rubber is employed as an external coating on marine vessels. Acoustic metamaterial designs primarily comprise cavities and hard scatterers in soft rubber, which has a similar impedance to that of water. This project will numerically and experimentally investigate the acoustic performance of metamaterials designs. 

Research Area

Computational mechanics |
Computational acoustics |
Materials |
Waves in complex media

The numerical part of this work will be conducted using the finite element software COMSOL Multiphysics. The computer facilities and research licences for this project are readily available. In this project, 2D numerical models to calculate the absorption coefficient of acoustic coating designs will be developed. A typical model will comprise a soft elastic medium embedded with periodic resonant inclusions. The soft medium is attached to a steel plate and has water on the incidence side and air on the transmission side. The experimental part of this work involves conducting experiments on samples in a water-filled impedance tube that was recently designed, built and commissioned in the School of Mechanical and Manufacturing Engineering. Samples will be prepared using polydimethylsiloxane (PDMS) which is a soft rubber like material. The PDMS is an elastomer polymer in solution (parts A and B). Manufacture of a design of PDMS with resonant inclusions will involve placing recycled spherical soda-silica glass (for voided inclusions) or steel balls (for hard inclusions) in the PDMS solution in a non-curing stage and heating in a furnace. All numerical and experimental facilities are available within the School of Mechanical and Manufacturing Engineering.

This project will generate new knowledge on sound absorption performance of acoustic coatings for marine vessels. The successful outcomes of this project will be communicated to the Maritime Division of the Defence Science and Technology Group. A further expected outcome of this project is a high quality journal publication.