NONLINEARITY BASED ACOUSTIC WAVE REDIRECTION

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dc.contributor.advisorBalachandran, Balakumaren_US
dc.contributor.authorTelly, Saliou Bineten_US
dc.contributor.departmentMechanical Engineeringen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2019-06-19T05:34:35Z
dc.date.available2019-06-19T05:34:35Z
dc.date.issued2019en_US
dc.description.abstractAdvances in metamaterials technology have revealed novel opportunities for achieving peculiar material properties amenable to the control of wave propagation paths for various applications not realizable with conventional materials. Some prominent examples are schemes for electromagnetic and acoustic cloaking and focusing devices. In the classical approach to the formulations of these devices, one exploits a change of physical coordinates to achieve a desired wave behavior within a finite space. Such a change can be interpreted as a transformation of material properties when the field equations of interest are invariant to coordinate trans- formations. To date, this intuitive approach has led to the formulation of various two-dimensional devices for wave redirection, including infinite circular and square cloaks for both electromagnetic and acoustic fields. For acoustic fields, however, the transformation approach is constrained to fluid-like metamaterials amenable to the propagation of longitudinal waves only. Complications arise with solid materials because of their inherent ability to sustain the propagation of both longitudinal and transverse waves, which refract differently in linear materials due to dissimilar propagation speeds. In this dissertation, the author first seeks a sequence of transformations that may be used for cloaking two-dimensional airfoil sections through the classical transformation method. For the sought sequence, the author takes advantage of the mapping properties of the Joukowsky Transformation, and the closely related Kaman-Trefftz Transformation, which are two well-known complex mappings that have classically been used in the study of the aerodynamics of airfoil sections. Next, the author explores wave redirection mechanisms that may take advantage of nonlinear wave phenomena in elastic solid materials for acoustic wave redirection. Starting from the classical nonlinear Murnaghan model, a hyper-elastic material is formulated to realize couplings between shear and compressional modes that could lead to a more suitable refractive behavior for acoustic wave redirection in a solid metamaterial. The formulated model is studied by using perturbation and approximation techniques. The findings of this dissertation can be useful for redirecting and manipulating acoustic waves for practical applications.en_US
dc.identifierhttps://doi.org/10.13016/lspr-qwbx
dc.identifier.urihttp://hdl.handle.net/1903/21894
dc.language.isoenen_US
dc.subject.pqcontrolledMechanical engineeringen_US
dc.subject.pqcontrolledAcousticsen_US
dc.subject.pqcontrolledMaterials Scienceen_US
dc.subject.pquncontrolledAcousticen_US
dc.subject.pquncontrolledCloakingen_US
dc.subject.pquncontrolledElectromagneticen_US
dc.subject.pquncontrolledMetamaterialen_US
dc.subject.pquncontrolledTransformation methoden_US
dc.subject.pquncontrolledWave redirectionen_US
dc.titleNONLINEARITY BASED ACOUSTIC WAVE REDIRECTIONen_US
dc.typeDissertationen_US

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