Collaborative Research: Accurate Determination of Acoustic Wave Sources using Periodic Microstructured Materials

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The goal of this project is to exploit the dynamic behavior of microstructured periodic materials to accurately locate the sources of sound waves. The traditional method of identifying source location is using phased array sensors whose precision is limited by the size of the sensor in comparison with the wavelength of acoustic waves. This research will aim to use the vibrational properties of periodic composites to improve determination of source location. The principles developed will have direct application to radar and associated technologies in both defense and civil applications. Through various outreach efforts, this research will help in broadening the participation of the public in the highly multi-disciplinary subject of waves and their control.Level Repulsion (LR) zones are frequency regions where the state of a periodic microstructured material undergoes rapid change in response to minute changes in a controlling parameter, e.g. wave incidence angle. Therefore they may be utilized for precise measurement of their controlling parameter, for example, the bearing angle of an incident stress wave. The principal research objectives of this project are: (a) To determine the conditions under which phononic eigenvalues coalesce to give rise to LR zones and to exploit this to demonstrate that phononic crystals can act as extremely sensitive directional sensors near LR zones; (b) To establish the relationships between the sensitivity of localization and the topological properties of LR zones in order to create tuned/tunable LR zones through modulations in the geometry or material properties of the PC; and (c) To create lab-scale phononic crystals and demonstrate the existence of LR zones, followed by verification of precision and robustness of the developed source localization methods in noisy and multisource environments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.