Collaborative Research: Design and Reconfiguration of Curved Surfaces for Targeted Wave Propagation

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This grant will fund research that enables the adaptive steering of acoustic waves through engineered or biological structures, with application to the control of structure borne noise, harnessing of vibrational energy, diagnostic imaging, and wireless energy transfer to implanted medical devices, thereby promoting the progress of science, and advancing the national prosperity. Through complex spatial patterning of mechanical properties, materials may be designed to guide acoustic wave energy in desirable directions through a structure. Such materials may be difficult to fabricate and challenging, if not impossible, to modify in real time. To address these limitations, this project will investigate reliance on the geometric shape of curved, thin elastic structures to achieve desirable waveguiding effects without the need for spatial inhomogeneity and with the possibility of adaptive on-demand reconfigurability. Theoretical insights will be combined with new tools for design and manufacturing to select and fabricate shapes whose geometry endows them with specific acoustic wave properties. Activities aimed at achieving broader impacts include research experiences and mentorship for high school and undergraduate students, as well as the development of table-top hands-on demos for public outreach and high school teacher training.This research aims to characterize flexural wave propagation on thin, curved shells and to determine how shape-morphing shell geometries can be used to design tunable and real-time adaptive acoustic waveguides. It accomplishes these outcomes through a combination of analytical and numerical calculations, physical experiments, and the development of innovative fabrication techniques. Geometric lensing of acoustic waves on curved surfaces will be analyzed in terms of the influence of anisotropy, constant or spatially varying thickness, and constitutive effects that couple membrane-like (in-plane) and flexural (out-of-plane) motion, with particular interest in propagation through curves of vanishing normal curvature. A modular approach to waveguide design will be developed in which precise patterns of localized Gaussian curvature can be realized to achieve complex global behavior. Finally, reconfigurability will be achieved by switching between multiple mechanically stable shapes, including through transitions induced by the excitation of resonant eigenmodes of vibration.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.