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2019_Zou_Chengzhe_dissertation.pdf (22.27 MB)

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Structural Acoustics of Reconfigurable Tessellated Arrays for Acoustic Energy Guiding

Zou, Chengzhe
http://rave.ohiolink.edu/etdc/view?acc_num=osu1574285872850491

Abstract Details

, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
Guided acoustic energies have been widely leveraged in various scientific and engineering fields. The purpose of this research is to guide the acoustic energy via reconfigurable tessellated arrays. In this concept, acoustic transducers are mounted on the facets of origami-inspired tessellations. Consequently, the folding-induced shape change of origami tessellations directly controls the acoustic wave propagation radiated from the transducers. In addition, the low-dimensionality of origami-inspired architectures enables simple and repeatable structural reconfigurations. As a result, compared with conventional digital methods of acoustic wave control, this concept may be more robust in effective acoustic energy guiding as well as less complex to implement. Moreover, the folding structures may facilitate portable systems. A general theoretical framework is required to explore the roles of mechanical reconfiguration of origami tessellations on acoustic field tailoring. The framework is developed by studying a star-shaped constituent for far field directivity and near field energy focusing, in which Rayleigh’s integral is evaluated over the tessellated facets to characterize the radiated acoustic pressure. Following validation by experiments and numerical verification by boundary element method, the accuracy of established framework is confirmed. Leveraging the analytical tool, it is found out that the adaptations enabled by the folding of the star-shaped transducer is able to tune the sound energy in both near and far fields. Beyond that, the line array assembled from the star-shaped constituents is studied via the same tool. The array results suggest that reconfigurable tessellated arrays may guide waves more effectively than traditional digitally phased arrays using less transducer elements. Moreover, it is discovered that refinement of tessellated arrays trends to the ideal case of classical wave radiators grounded in principles of geometrical acoustics. In the initial analytical modeling framework, only the direct radiation from oscillating facets is considered. Yet, the spatial translations and rotations of transducers in tessellated arrays may lead to reflected and diffracted waves. To illuminate such wave phenomena, the reflection and diffraction induced from a Miura-ori based acoustic array are examined. As tessellated arrays take on highly folded configurations, reflected waves are shown to greatly contribute to the broadside, whereas diffracted waves primarily govern the acoustic pressure for endfire locations. The analytical framework devised here sheds light on these attributes for the first time, which enriches the understanding of how array reconfiguration alters the interferences. In order to fully release the potential of this concept, the design problem is solved to develop tessellations that can achieve pre-defined acoustic metrics. The previously established framework is used to determine the tessellations that is able to target desirable beam pattern. To facilitate the design problem, genetic algorithm (GA) optimization is formulated to obtain the optimal tessellated array. The GA outcome is interpreted via inverse analytical expressions, which give the sensitivities of design parameters on acoustic fields. Directed by the design principles, proof-of-concept specimens are fabricated and the experimental results indicate that desired acoustic characteristics are physically realized. The advantages of this concept may be uncovered by two applications: acoustic communication in far field and high intensity focused ultrasound (HIFU) in near field. In terms of acoustic communication, piecewise geometries assembled from multiple folding patterns are explored. It is revealed that such assembly may emulate the wave radiation emitted by acoustic sources of intricate shapes, which opens the door for broader acoustic field tailoring. To explore a vision of deployable HIFU transducers, the deployable tessellated acoustic array is employed to reduce the distance between HIFU transducer and diseased tissues. This may release the potential of HIFU from being limited by absorption, diffusion, and reflection of ultrasound. Theoretical and numerical methods are used to study the capabilities of deployable HIFU transducer, and the results encourage attention to foldable array as potential means to advance HIFU-based procedures. The concept of guiding acoustic energy via reconfigurable tessellated acoustic arrays is presented through this work. Via the developed theoretical framework, the underlying physical principles of wave propagation from reconfigurable tessellated acoustic arrays are uncovered. In addition, the potential applications that may be advanced by this concept are preliminarily studied. Empowered with simple and significant tuning capability, this concept may propel future classes of acoustic energy guiding systems. Furthermore, by wave physics shared among myriad scientific disciplines, this scale-independent idea may cultivate adaptive structures in other wave physics, e.g. electromagnetics and optics, for wave guiding.
Haijun Su (Committee Chair)
Ahmet Selamet (Committee Member)
Carlos Castro (Committee Member)
193 p.
Acoustics; Mechanical Engineering

Recommended Citations

Citations

  • Zou, C. (2019). Structural Acoustics of Reconfigurable Tessellated Arrays for Acoustic Energy Guiding [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574285872850491

    APA Style (7th edition)

  • Zou, Chengzhe. Structural Acoustics of Reconfigurable Tessellated Arrays for Acoustic Energy Guiding . 2019. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1574285872850491.

    MLA Style (8th edition)

  • Zou, Chengzhe. "Structural Acoustics of Reconfigurable Tessellated Arrays for Acoustic Energy Guiding ." Doctoral dissertation, Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1574285872850491

    Chicago Manual of Style (17th edition)

osu1574285872850491
211
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