التفاصيل البيبلوغرافية
| العنوان: |
Controlling wave propagation with acoustic and elastic metamaterials |
| المساهمون: |
Kelsten, Matthew J (author), Norris, Andrew (chair), Singer, Jonathan (member), Bottega, William (member), Haberman, Michael (member), Rutgers University, School of Graduate Studies |
| سنة النشر: |
2021 |
| المجموعة: |
RUcore - Rutgers University Community Repository |
| مصطلحات موضوعية: |
Acoustics, Engineering, Physics, exceptional points, finite element method, impedance tube, metamaterials, pentamode, wave propagation |
| الوصف: |
The topics deliberated in this dissertation are ingrained in the idea of controlling wave transmission through artificial domains. This is accomplished through modeling, simulating, design, and testing of acoustic and elastic metamaterials for both air and water applications. Effective properties of metamaterials vastly increase the design-space used toachieve high, low, anisotropic, or one-wave transmission. Each idea presented is focused on realizing or optimizing one of those transmission types. The first topic visited is optimal attenuation in air-filled ducts. Non-Hermitian systems can exhibit “exceptional points” (EPs) at which modes coalesce. The connection between EPs and acoustic damping goes back to the observation of Cremer (1953) that optimal attenuation in a duct occurs when the two lowest modes have equal complex-valued eigenvalues. An EP existence condition is derived, doing so allows for the determination of the complete set of all possible passive impedance conditions that give rise to EPs, and from these to select impedances appropriate to a particular frequency band. We consider a novel approach to feasibly achieve the aforementioned wall impedance with the use of simple resonators, which can be shown to exhibit mode coalescence at distinct frequencies when treated as a unit cell component of a larger metasurface. The second topic discussed delves into the interest for developing the three-dimensional (3D) anisotropic pentamode (PM), i.e. a structure designed to support a single longitudinal wave with sound speed that depends on the propagation direction, specifically for underwater applications. The presented work attempts to experimentally verify anisotropic sound speeds predicted by finite element simulations using additively manufactured anisotropic 3D PM samples made of titanium. Simulation techniques are given for the computational evaluation of PM sound speeds and the acoustic response of PM materials. Measurements involved suspending samples in front of a plane-wave source emitting a ... |
| نوع الوثيقة: |
thesis |
| وصف الملف: |
1 online resource (xx, 156 pages); application/pdf |
| اللغة: |
English |
| العلاقة: |
Rutgers University Electronic Theses and Dissertations; ETD; School of Graduate Studies Electronic Theses and Dissertations; rucore10001600001; http://dissertations.umi.com/gsnb.rutgers:11544Test |
| الإتاحة: |
http://dissertations.umi.com/gsnb.rutgers:11544Test |
| حقوق: |
The author owns the copyright to this work. |
| رقم الانضمام: |
edsbas.19BB4B63 |
| قاعدة البيانات: |
BASE |
