| NSF Org: |
CMMI Division of Civil, Mechanical, and Manufacturing Innovation |
| Recipient: |
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| Initial Amendment Date: | August 1, 2018 |
| Latest Amendment Date: | August 1, 2018 |
| Award Number: | 1825354 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Eva Kanso
CMMI Division of Civil, Mechanical, and Manufacturing Innovation ENG Directorate for Engineering |
| Start Date: | September 1, 2018 |
| End Date: | August 31, 2022 (Estimated) |
| Total Intended Award Amount: | $237,453.00 |
| Total Awarded Amount to Date: | $237,453.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
10 W 35TH ST CHICAGO IL US 60616-3717 (312)567-3035 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
10 West 32nd Street Chicago IL US 60616-4277 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Dynamics, Control and System D |
| Primary Program Source: |
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| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.041 |
ABSTRACT
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.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
An important problem in many areas of engineering is the accurate detemination (localization of sources) of the direction from which a certain wave is coming. This problem is relevant to both electromagnetic waves and sound waves and is applicable to fields such as radar and sonar. The traditional method of localization of sources is based upon phased arrays and the associated algorithms. This project focused on using phononic crystals instead of phased arrays and to hone the localization algorithms as guided by the unique wave physics of the phononic crystals. When waves are incident on phononic crystals then they scatter in all directions and the scattering amplitudes in different directions is connected to the properties of the crystal itself. The project focused on understanding this connection and if these connections can be exploited for better design of phononic crystals for the purpose of localization.
An important progress which was made during this project was establishing connections between regions of rapid fluctuation in the scattering amplitude to the internal resonances (exceptional points) of the phononic crystal itself. These resonances are captured in a property of the phononic crystal called the effective Hamiltonian. If one can calculate the effective Hamiltonian for any given crystal, then one would be able to find out the locations of it resonances and, thereby, be able to predict the directions in which can expect the scattered waves to show rapid fluctuations. The main problem of this project thus reduces to devising stratgies for the determination of the effective Hamiltonian. This is no trivial task for an arbitrary crystal as it requires the inversion of an infinitely large matrix.
As another important outcome of this project, we borrowed from progress made in the fields of quantum mechanics and nanoscale heat transfer to devise a method for the calculation of the effective Hamiltonian of phononic crystals. We showed how the method can be used to determine the resonances of phononic crystals and we showed how these resonances are then connected to the rapid fluctuation of the scattered field.
The project has allowed for training of two PhD students and also for the research experience of several undergraduate students at IIT. One of the PhD student has graduated and is now working in Knowles - a leader in the design and manufacture of MEMS based vibration sensors. His experience in this project is, therefore, directly relevant to the job he is doing. Some of the results of the project have also percolated in the graduate curriculum at IIT in the "Vibrations" course and in the undergrad curriculum in the "Computational Mechanics" course.
Last Modified: 01/16/2023
Modified by: Ankit Srivastava
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