Acoustic Black Holes for Control of Structural Vibration and Sound Radiation

Lead Research Organisation: University of Southampton
Department Name: Faculty of Engineering & the Environment

Abstract

Acoustic black holes (ABHs), which are based on introducing carefully designed geometrical features to a structure, have been shown to achieve significant levels of structural damping in both beams and plates. The aim of this project is to develop the design, optimisation and practical implementation of ABHs and, therefore, facilitate their exploitation in complex practical structures. In particular, the project may investigate the interaction between multiple ABHs and also explore methods of optimising their locations on complex structures to minimize either structural vibration or sound radiation. Additionally, the integration of active technologies into the design of ABHs may also be explored. The specific focus of the research is likely to depend on the skills and interests of the successful candidate, but is will involve a mixture of theoretical, numerical and experimental investigation

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/P510646/1 01/10/2016 30/09/2021
1941775 Studentship EP/P510646/1 09/01/2017 31/12/2020 Kristian Hook
 
Description *This award is still in progress.

The objective of this research into 'Acoustic Black Holes' (ABHs) is to create a broadband structural damping solution that can attenuate both structural vibration and reduce sound radiation from the structure. ABHs are structural features that are realised by introducing a taper, defined by a power law for example, into a beam or plate. The decrease in thickness associated with the taper causes the wave speed in the ABH to decrease, theoretically to zero at zero thickness. So far, adding passive damping to practically designed ABHs has been shown to be effective at attenuating vibration above the first modal frequency of the ABH. The first investigation carried out under this award examined how the different ABH design parameters: taper length, tip height and power law, could be used to minimise the reflected wave from the ABH. This built upon the literature that had, so far, only investigated specific design cases and gave a good insight into both the frequency dependancy of the performance on each parameter and also how the broadband performance of an ABH can be tunes using each parameter. Particularly, it was noted that the power law could be used to tune the ABH in industrial applications where the taper length and tip height are constrained. The work was presented at the ISMA2018 conference and is undergoing corrections for publication in the Journal of the Acoustical Society of America.

The investigation into ABHs has now moved on and is currently focussed the integration of a hybrid of active and passive components in an attempt to improve the low frequency performance of an ABH.
Exploitation Route The results from the parameter study may be used as guidance for the design of industrial ABHs. The investigation into improving the low frequency performance of ABHs is currently active and so the future of this is currently unknown.
Sectors Aerospace, Defence and Marine,Construction

URL http://past.isma-isaac.be/isma2018/proceedings/program/