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Coupling of a Granular Chain to an Acoustic Medium: Sensitivity Analyses of the Propagation of Ultrasonic Pulse Trains

Gelat, P; Saffari, N; Yang, J; Akanji, O; Thomas, PJ; Hutchins, DA; Harput, S; (2016) Coupling of a Granular Chain to an Acoustic Medium: Sensitivity Analyses of the Propagation of Ultrasonic Pulse Trains. In: Proceedings of the Ultrasonics Symposium (IUS), 2016 IEEE International. IEEE Green open access

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Abstract

Effects which arise as a result of Hertzian contact between adjacent spheres of a granular chain can potentially change the nature of a signal as it propagates down the chain. The possibility thus exists of generating signals with a different harmonic content to the signal input into one end of the chain. This transduction mechanism has the potential to be of use in both diagnostic and therapeutic ultrasound applications. Due to metrological challenges which arise when characterizing this transduction process, numerical models play a fundamental role in assisting the design of these novel devices. Previously, a finite element model was presented, which predicts the acoustic pressure generated by a sinusoidally excited granular chain coupled into an acoustic medium. The study described here exploits this model to carry out sensitivity analyses of the system to key input parameters, including excitation frequency and amplitude, sphere diameter and the number of spheres present in the chain. Granular chains were excited at one end using tone burst displacement signals with fundamental frequencies of 73 kHz and 100 kHz. The final sphere of the chain was assumed to be in contact with a cylindrical vitreous carbon layer, coupled to a half-space of water. Using the finite element method, it was possible to predict the acoustic pressure in the fluid, for a specific dynamic excitation of the first sphere of the granular chain. The sensitivity analyses demonstrated that, under tone burst excitation conditions, a train of impulses could be propagated into an acoustic medium. The sensitivity analyses also show that, due to inherent nonlinearities present in this type of system, the time and frequency domain characteristics of the signals are highly sensitive to input conditions.

Type: Proceedings paper
Title: Coupling of a Granular Chain to an Acoustic Medium: Sensitivity Analyses of the Propagation of Ultrasonic Pulse Trains
Event: IEEE International Ultrasonics Symposium (IUS)
Location: Tours, FRANCE
Dates: 18 September 2016 - 21 September 2016
ISBN-13: 978-1-4673-9898-5
Open access status: An open access version is available from UCL Discovery
DOI: 10.1109/ULTSYM.2016.7728759
Publisher version: http://dx.doi.org/10.1109/ULTSYM.2016.7728759
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Science & Technology, Technology, Engineering, Electrical & Electronic, Engineering, Finite element analysis, Granular chain, Nonlinear systems, Ultrasonic transducers
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Surgery and Interventional Sci
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Surgery and Interventional Sci > Department of Surgical Biotechnology
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/1533577
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