Title:
Acoustic Metamaterials for Enhanced Wave Control

dc.contributor.advisor Shi, Chengzhi
dc.contributor.author Craig, Steven R.
dc.contributor.committeeMember Sabra, Karim
dc.contributor.committeeMember Meaud, Julien
dc.contributor.committeeMember Hu, Yuhang
dc.contributor.committeeMember Joseph, Roshan
dc.contributor.committeeMember Leamy, Michael
dc.contributor.department Mechanical Engineering
dc.date.accessioned 2023-01-10T16:25:38Z
dc.date.available 2023-01-10T16:25:38Z
dc.date.created 2022-12
dc.date.issued 2022-12-13
dc.date.submitted December 2022
dc.date.updated 2023-01-10T16:25:38Z
dc.description.abstract Acoustic metamaterials have redefined the limits of acoustic wave control with composite structures that realize effective material properties that go beyond those of natural materials. These extraordinary material properties enable imaging beyond the diffraction limit, negative effective sound speeds, and acoustic cloaking. Metamaterials continue to be a hot topic in the scientific community, as these resonant structures push the boundaries of acoustic wave control with unprecedented functionality. The primary goal of this work is to advance the prevalence, practicality, and scope of acoustic metamaterial research with novel materials that uniquely tailor wave fields for a variety of acoustic-based applications. Each chapter uses foundational metamaterial physics to advance our understanding of acoustic wave control with composite structures. The first section develops the theory and performs simulations for a non-Hermitian complementary metamaterial (NHCMM) with tunable active feedback loop circuits that improve the acoustic transmission through an intact human skull. This lays the foundation for ultrasonic brain imaging and neural therapies that require high frequency acoustic waves to penetrate deep within the brain. With a similarly designed metamaterial, we compare the accessible range of the effective density and bulk modulus for unit cells with symmetric and asymmetric feedback loop circuits. The asymmetric circuits result in a Willis coupled response that dramatically broadens the metamaterial’s attainable parameter range. We also demonstrate asymmetric wave transmission at high efficiency with passive Willis coupled metagratings for acoustic beam steering at extreme angles. Lastly, we use transformation acoustics to correct focused and self-bending acoustic beams that become distorted in anisotropic media. These developments advance acoustic-based technologies for biomedical imaging, noise control, underwater communication, and structural acoustic applications.
dc.description.degree Ph.D.
dc.format.mimetype application/pdf
dc.identifier.uri http://hdl.handle.net/1853/70178
dc.language.iso en_US
dc.publisher Georgia Institute of Technology
dc.subject Acoustics
dc.subject Acoustic Metamaterials
dc.subject Non-Hermitian Complementary Acoustic Metamaterials
dc.subject Willis Coupling
dc.subject Transformation Acoustics
dc.title Acoustic Metamaterials for Enhanced Wave Control
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.advisor Shi, Chengzhi
local.contributor.corporatename George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename College of Engineering
relation.isAdvisorOfPublication ccc207c0-2423-4c6f-a1f4-15de996c4a97
relation.isOrgUnitOfPublication c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
thesis.degree.level Doctoral
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