Jalali Najafabadi, Hoda
(2022)
Applications of Granular Crystals for Nondestructive Evaluation, Structural Health Monitoring, and Mechanical Wave Control.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Granular crystals are a class of nonlinear periodic structures in form of arrays of elastic particles that interact nonlinearly via Hertzian contact. The structural discreteness and nonlinearity of granular crystals can be used to control the propagation of mechanical waves. In addition, their mechanical response can be tailored by adjusting their composition and loading conditions. On account of these properties, granular crystals offer several potential engineering applications like shock-absorbing, energy harvesting, acoustic switching, nondestructive evaluation (NDE), and structural health monitoring (SHM).
A 1D granular crystal composed of identical spherical particles subjected to zero or weak static compression supports the generation and propagation of highly nonlinear solitary waves (HNSWs). The interaction of HNSWs with a given material/structure of interest is affected by the mechanical properties and the geometry of the interacting material/structure. Therefore, HNSWs have gained research attention in NDE and SHM applications recently.
This dissertation investigates the application of HNSWs for the detection of localized corrosion in steel structures, and the identification and characterization of anisotropy in rocks. Numerical simulations were conducted to study the interaction of HNSWs with steel plates and rock materials of different conditions. Furthermore, the application of the HNSWs for the mentioned NDE applications was examined experimentally. The experimental data were analyzed using multivariate statistical methods to enhance the performance of the proposed NDE method. The present study provides evidence for the effectiveness
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of the HNSWs-based NDE method in detecting localized corrosion in plate-like structures and in detecting anisotropy in rocks. In addition, this study investigates the long-term performance of the developed HNSW-based NDE method using video processing techniques.
Finally, this dissertation investigates the asymmetric propagation of mechanical waves in a compressed 1D granular crystal of spherical particles coupled with asymmetric intruders. A numerical analysis was conducted to investigate the dynamic response of the system subjected to small-amplitude periodic vibrations. It was shown that the proposed design can provide unidirectional transmission of low-frequency mechanical waves.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
10 June 2022 |
| Date Type: |
Publication |
| Defense Date: |
1 March 2022 |
| Approval Date: |
10 June 2022 |
| Submission Date: |
21 March 2022 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
215 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Civil and Environmental Engineering |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Granular crystals, Solitary waves, Nondestructive evaluation, Structural health monitoring |
| Date Deposited: |
10 Jun 2022 18:18 |
| Last Modified: |
10 Jun 2022 18:18 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/42390 |
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