| NSF Org: |
CMMI Division of Civil, Mechanical, and Manufacturing Innovation |
| Recipient: |
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| Initial Amendment Date: | September 11, 2012 |
| Latest Amendment Date: | September 11, 2012 |
| Award Number: | 1232423 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Atul Kelkar
CMMI Division of Civil, Mechanical, and Manufacturing Innovation ENG Directorate for Engineering |
| Start Date: | September 15, 2012 |
| End Date: | August 31, 2016 (Estimated) |
| Total Intended Award Amount: | $184,603.00 |
| Total Awarded Amount to Date: | $184,603.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
940 GRACE HALL NOTRE DAME IN US 46556-5708 (574)631-7432 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
IN US 46556-5612 |
| 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): | DYNAMICAL SYSTEMS |
| 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 main objective of this research is to advance the state of the art of Structural Health Monitoring
(SHM) systems by creating novel Frequency Selective Structures (FSS) and an FSS-based
Impediographic monitoring technique. The proposed approach is based on the concept of concurrent
design where the SHM system is no longer retrofitted to an existing structure but, instead, it is designed
concurrently with the structure itself. The system is achieved by implementing the idea of Frequency
Selective Structure. FSS exploit the concept of mistuned periodic structures as a general framework to
synthesize dynamically tailored components with self-focusing vibration energy capabilities. The new
structural design approach will allow delivering targeted excitation to the damaged areas even in complex,
non homogeneous components. The integration of FSS with the impediographic approach will then enable
advanced damage identification capabilities characterized by high sensitivity, high resolution and a
minimized transducer and sensory network.
If successful, this research will create a transformative intellectual pathway in synthesizing novel and
realistic structural damage identification methods of the next generation for complex mechanical systems.
The technology will have general applicability and could be implemented across the aerospace,
mechanical and civil engineering fields leading to the next generation of transportation and infrastructure
systems having advanced health monitoring capabilities. The proposed technology will also eliminate the
barriers that have prevented, to date, the experimental implementation and validation of the
impediographic approach. Experimental findings will allow an unprecedented insight into impediography
and provide critical inputs to foster its application to diverse fields, such as medical imaging, where
remote non-invasive monitoring techniques are of primary importance. The results will be disseminated
through classroom teaching, undergraduate and graduate student mentoring, community outreach, and
collaboration with potential users.
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.
The main goal of this project is to develop a multi-physics tomographic imaging technology for the non-destructive assessment and monitoring of damage in structural systems. Structural monitoring systems are enabling technologies with the potential to increase safety and reliability of the transportation and infrastructure system while largely reducing their maintenance costs. The ability to monitor a system in operating conditions can extend the operational life, and drastically reduce unnecessary maintenance and downtime, therefore laying the foundation for efficient, safe, and sustainable future transportation and infrastructures. Tomographic imaging is a discipline that finds applications in many fields of science and engineering; biomedical imaging, underground and underwater sensing, and material characterization are just a few examples. It is expected that the results and methodologies developed in this project could also be beneficial to these areas.
More specifically, the tomographic approach developed in this research is able to reconstruct a high-resolution image of the interior of the structure by using coupled electrical and ultrasonic stimuli. The system to be monitored is probed only at its outer surface, therefore without requiring any direct and invasive access to the structure’s interior. The reconstructed images provide a map of the internal electrical properties of the structure that can be connected to the existence of damage in order to assess the system’s integrity. The key to achieve high-resolution lies in the coupling between the electrical and the mechanical response of the host system. In order to take advantage of this coupling, highly focused mechanical perturbations are generated via targeted ultrasonic excitation. Focusing ultrasounds typically requires a large number of transducers which, ultimately, increases the complexity of the system and the possibility of malfunctions and false alarms. To overcome this issue, a novel structural design concept based on the idea of mistuned periodic structures was developed. The design, referred to as Frequency Selective Structure, turns the host system into a focusing lens able to achieve targeted ultrasonic interrogation by using a single source. The target location can be simply selected by a proper choice of the excitation frequency of the source.
During the course of this project theoretical and numerical tools were developed to enable the application of impediography to structural damage detection. These tools allow for both the numerical simulation of the tomographic imaging method in two-dimensional structures and the analysis of experimental data. Numerical results confirmed the large increase in sensitivity and resolution compared to traditional tomographic methods. Dedicated laboratory experiments were also designed and conducted in order to validate the approach and assess the performance. In particular, experimental results proved the efficacy of the frequency selective structure approach in obtaining targeted ultrasonic excitation while using a minimum-size sensing network.
Last Modified: 11/29/2016
Modified by: Fabio Semperlotti
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